Linux Networking and Network Devices APIs

Linux Networking

Networking Base Types

enum sock_type

Socket types

Constants

SOCK_STREAM
stream (connection) socket
SOCK_DGRAM
datagram (conn.less) socket
SOCK_RAW
raw socket
SOCK_RDM
reliably-delivered message
SOCK_SEQPACKET
sequential packet socket
SOCK_DCCP
Datagram Congestion Control Protocol socket
SOCK_PACKET
linux specific way of getting packets at the dev level. For writing rarp and other similar things on the user level.

Description

When adding some new socket type please grep ARCH_HAS_SOCKET_TYPE include/asm-* /socket.h, at least MIPS overrides this enum for binary compat reasons.

struct socket

general BSD socket

Definition

struct socket {
  socket_state state;
  short type;
  unsigned long           flags;
  struct socket_wq        *wq;
  struct file             *file;
  struct sock             *sk;
  const struct proto_ops  *ops;
};

Members

state
socket state (SS_CONNECTED, etc)
type
socket type (SOCK_STREAM, etc)
flags
socket flags (SOCK_NOSPACE, etc)
wq
wait queue for several uses
file
File back pointer for gc
sk
internal networking protocol agnostic socket representation
ops
protocol specific socket operations

Socket Buffer Functions

skb_frag_foreach_page(f, f_off, f_len, p, p_off, p_len, copied)

loop over pages in a fragment

Parameters

f
skb frag to operate on
f_off
offset from start of f->page.p
f_len
length from f_off to loop over
p
(temp var) current page
p_off
(temp var) offset from start of current page, non-zero only on first page.
p_len
(temp var) length in current page, < PAGE_SIZE only on first and last page.
copied
(temp var) length so far, excluding current p_len.

Description

A fragment can hold a compound page, in which case per-page operations, notably kmap_atomic, must be called for each regular page.
struct skb_shared_hwtstamps

hardware time stamps

Definition

struct skb_shared_hwtstamps {
  ktime_t hwtstamp;
};

Members

hwtstamp
hardware time stamp transformed into duration since arbitrary point in time

Description

Software time stamps generated by ktime_get_real() are stored in skb->tstamp.

hwtstamps can only be compared against other hwtstamps from the same device.

This structure is attached to packets as part of the skb_shared_info. Use skb_hwtstamps() to get a pointer.

struct sk_buff

socket buffer

Definition

struct sk_buff {
  union {
    struct {
      struct sk_buff          *next;
      struct sk_buff          *prev;
      union {
        struct net_device       *dev;
        unsigned long           dev_scratch;
      };
    };
    struct rb_node          rbnode;
    struct list_head        list;
  };
  union {
    struct sock             *sk;
    int ip_defrag_offset;
  };
  union {
    ktime_t tstamp;
    u64 skb_mstamp_ns;
  };
  char cb[48] ;
  union {
    struct {
      unsigned long   _skb_refdst;
      void (*destructor)(struct sk_buff *skb);
    };
    struct list_head        tcp_tsorted_anchor;
  };
#ifdef CONFIG_XFRM;
  struct sec_path        *sp;
#endif;
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE);
  unsigned long            _nfct;
#endif;
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER);
  struct nf_bridge_info   *nf_bridge;
#endif;
  unsigned int            len, data_len;
  __u16 mac_len, hdr_len;
  __u16 queue_mapping;
#ifdef __BIG_ENDIAN_BITFIELD;
#define CLONED_MASK     (1 << 7);
#else;
#define CLONED_MASK     1;
#endif;
#define CLONED_OFFSET()         offsetof(struct sk_buff, __cloned_offset);
  __u8 __cloned_offset[0];
  __u8 cloned:1,nohdr:1,fclone:2,peeked:1,head_frag:1,xmit_more:1, pfmemalloc:1;
#ifdef __BIG_ENDIAN_BITFIELD;
#define PKT_TYPE_MAX    (7 << 5);
#else;
#define PKT_TYPE_MAX    7;
#endif;
#define PKT_TYPE_OFFSET()       offsetof(struct sk_buff, __pkt_type_offset);
  __u8 __pkt_type_offset[0];
  __u8 pkt_type:3;
  __u8 ignore_df:1;
  __u8 nf_trace:1;
  __u8 ip_summed:2;
  __u8 ooo_okay:1;
  __u8 l4_hash:1;
  __u8 sw_hash:1;
  __u8 wifi_acked_valid:1;
  __u8 wifi_acked:1;
  __u8 no_fcs:1;
  __u8 encapsulation:1;
  __u8 encap_hdr_csum:1;
  __u8 csum_valid:1;
  __u8 csum_complete_sw:1;
  __u8 csum_level:2;
  __u8 csum_not_inet:1;
  __u8 dst_pending_confirm:1;
#ifdef CONFIG_IPV6_NDISC_NODETYPE;
  __u8 ndisc_nodetype:2;
#endif;
  __u8 ipvs_property:1;
  __u8 inner_protocol_type:1;
  __u8 remcsum_offload:1;
#ifdef CONFIG_NET_SWITCHDEV;
  __u8 offload_fwd_mark:1;
  __u8 offload_mr_fwd_mark:1;
#endif;
#ifdef CONFIG_NET_CLS_ACT;
  __u8 tc_skip_classify:1;
  __u8 tc_at_ingress:1;
  __u8 tc_redirected:1;
  __u8 tc_from_ingress:1;
#endif;
#ifdef CONFIG_TLS_DEVICE;
  __u8 decrypted:1;
#endif;
#ifdef CONFIG_NET_SCHED;
  __u16 tc_index;
#endif;
  union {
    __wsum csum;
    struct {
      __u16 csum_start;
      __u16 csum_offset;
    };
  };
  __u32 priority;
  int skb_iif;
  __u32 hash;
  __be16 vlan_proto;
  __u16 vlan_tci;
#if defined(CONFIG_NET_RX_BUSY_POLL) || defined(CONFIG_XPS);
  union {
    unsigned int    napi_id;
    unsigned int    sender_cpu;
  };
#endif;
#ifdef CONFIG_NETWORK_SECMARK;
  __u32 secmark;
#endif;
  union {
    __u32 mark;
    __u32 reserved_tailroom;
  };
  union {
    __be16 inner_protocol;
    __u8 inner_ipproto;
  };
  __u16 inner_transport_header;
  __u16 inner_network_header;
  __u16 inner_mac_header;
  __be16 protocol;
  __u16 transport_header;
  __u16 network_header;
  __u16 mac_header;
  sk_buff_data_t tail;
  sk_buff_data_t end;
  unsigned char           *head, *data;
  unsigned int            truesize;
  refcount_t users;
};

Members

{unnamed_union}
anonymous
{unnamed_struct}
anonymous
next
Next buffer in list
prev
Previous buffer in list
{unnamed_union}
anonymous
dev
Device we arrived on/are leaving by
rbnode
RB tree node, alternative to next/prev for netem/tcp
{unnamed_union}
anonymous
sk
Socket we are owned by
{unnamed_union}
anonymous
tstamp
Time we arrived/left
cb
Control buffer. Free for use by every layer. Put private vars here
{unnamed_union}
anonymous
{unnamed_struct}
anonymous
_skb_refdst
destination entry (with norefcount bit)
destructor
Destruct function
tcp_tsorted_anchor
list structure for TCP (tp->tsorted_sent_queue)
sp
the security path, used for xfrm
_nfct
Associated connection, if any (with nfctinfo bits)
nf_bridge
Saved data about a bridged frame - see br_netfilter.c
len
Length of actual data
data_len
Data length
mac_len
Length of link layer header
hdr_len
writable header length of cloned skb
queue_mapping
Queue mapping for multiqueue devices
cloned
Head may be cloned (check refcnt to be sure)
nohdr
Payload reference only, must not modify header
fclone
skbuff clone status
peeked
this packet has been seen already, so stats have been done for it, don’t do them again
xmit_more
More SKBs are pending for this queue
pfmemalloc
skbuff was allocated from PFMEMALLOC reserves
pkt_type
Packet class
ignore_df
allow local fragmentation
nf_trace
netfilter packet trace flag
ip_summed
Driver fed us an IP checksum
ooo_okay
allow the mapping of a socket to a queue to be changed
l4_hash
indicate hash is a canonical 4-tuple hash over transport ports.
sw_hash
indicates hash was computed in software stack
wifi_acked_valid
wifi_acked was set
wifi_acked
whether frame was acked on wifi or not
no_fcs
Request NIC to treat last 4 bytes as Ethernet FCS
csum_not_inet
use CRC32c to resolve CHECKSUM_PARTIAL
dst_pending_confirm
need to confirm neighbour
ndisc_nodetype
router type (from link layer)
ipvs_property
skbuff is owned by ipvs
tc_skip_classify
do not classify packet. set by IFB device
tc_at_ingress
used within tc_classify to distinguish in/egress
tc_redirected
packet was redirected by a tc action
tc_from_ingress
if tc_redirected, tc_at_ingress at time of redirect
decrypted
Decrypted SKB
tc_index
Traffic control index
{unnamed_union}
anonymous
csum
Checksum (must include start/offset pair)
{unnamed_struct}
anonymous
csum_start
Offset from skb->head where checksumming should start
csum_offset
Offset from csum_start where checksum should be stored
priority
Packet queueing priority
skb_iif
ifindex of device we arrived on
hash
the packet hash
vlan_proto
vlan encapsulation protocol
vlan_tci
vlan tag control information
{unnamed_union}
anonymous
napi_id
id of the NAPI struct this skb came from
secmark
security marking
{unnamed_union}
anonymous
mark
Generic packet mark
{unnamed_union}
anonymous
inner_protocol
Protocol (encapsulation)
inner_transport_header
Inner transport layer header (encapsulation)
inner_network_header
Network layer header (encapsulation)
inner_mac_header
Link layer header (encapsulation)
protocol
Packet protocol from driver
transport_header
Transport layer header
network_header
Network layer header
mac_header
Link layer header
tail
Tail pointer
end
End pointer
head
Head of buffer
data
Data head pointer
truesize
Buffer size
users
User count - see {datagram,tcp}.c
struct dst_entry * skb_dst(const struct sk_buff * skb)

returns skb dst_entry

Parameters

const struct sk_buff * skb
buffer

Description

Returns skb dst_entry, regardless of reference taken or not.

void skb_dst_set(struct sk_buff * skb, struct dst_entry * dst)

sets skb dst

Parameters

struct sk_buff * skb
buffer
struct dst_entry * dst
dst entry

Description

Sets skb dst, assuming a reference was taken on dst and should be released by skb_dst_drop()

void skb_dst_set_noref(struct sk_buff * skb, struct dst_entry * dst)

sets skb dst, hopefully, without taking reference

Parameters

struct sk_buff * skb
buffer
struct dst_entry * dst
dst entry

Description

Sets skb dst, assuming a reference was not taken on dst. If dst entry is cached, we do not take reference and dst_release will be avoided by refdst_drop. If dst entry is not cached, we take reference, so that last dst_release can destroy the dst immediately.

bool skb_dst_is_noref(const struct sk_buff * skb)

Test if skb dst isn’t refcounted

Parameters

const struct sk_buff * skb
buffer
bool skb_fclone_busy(const struct sock * sk, const struct sk_buff * skb)

check if fclone is busy

Parameters

const struct sock * sk
socket
const struct sk_buff * skb
buffer

Description

Returns true if skb is a fast clone, and its clone is not freed. Some drivers call skb_orphan() in their ndo_start_xmit(), so we also check that this didnt happen.

int skb_pad(struct sk_buff * skb, int pad)

zero pad the tail of an skb

Parameters

struct sk_buff * skb
buffer to pad
int pad
space to pad

Description

Ensure that a buffer is followed by a padding area that is zero filled. Used by network drivers which may DMA or transfer data beyond the buffer end onto the wire.

May return error in out of memory cases. The skb is freed on error.

int skb_queue_empty(const struct sk_buff_head * list)

check if a queue is empty

Parameters

const struct sk_buff_head * list
queue head

Description

Returns true if the queue is empty, false otherwise.
bool skb_queue_is_last(const struct sk_buff_head * list, const struct sk_buff * skb)

check if skb is the last entry in the queue

Parameters

const struct sk_buff_head * list
queue head
const struct sk_buff * skb
buffer

Description

Returns true if skb is the last buffer on the list.
bool skb_queue_is_first(const struct sk_buff_head * list, const struct sk_buff * skb)

check if skb is the first entry in the queue

Parameters

const struct sk_buff_head * list
queue head
const struct sk_buff * skb
buffer

Description

Returns true if skb is the first buffer on the list.
struct sk_buff * skb_queue_next(const struct sk_buff_head * list, const struct sk_buff * skb)

return the next packet in the queue

Parameters

const struct sk_buff_head * list
queue head
const struct sk_buff * skb
current buffer

Description

Return the next packet in list after skb. It is only valid to call this if skb_queue_is_last() evaluates to false.
struct sk_buff * skb_queue_prev(const struct sk_buff_head * list, const struct sk_buff * skb)

return the prev packet in the queue

Parameters

const struct sk_buff_head * list
queue head
const struct sk_buff * skb
current buffer

Description

Return the prev packet in list before skb. It is only valid to call this if skb_queue_is_first() evaluates to false.
struct sk_buff * skb_get(struct sk_buff * skb)

reference buffer

Parameters

struct sk_buff * skb
buffer to reference

Description

Makes another reference to a socket buffer and returns a pointer to the buffer.
int skb_cloned(const struct sk_buff * skb)

is the buffer a clone

Parameters

const struct sk_buff * skb
buffer to check

Description

Returns true if the buffer was generated with skb_clone() and is one of multiple shared copies of the buffer. Cloned buffers are shared data so must not be written to under normal circumstances.
int skb_header_cloned(const struct sk_buff * skb)

is the header a clone

Parameters

const struct sk_buff * skb
buffer to check

Description

Returns true if modifying the header part of the buffer requires the data to be copied.
void __skb_header_release(struct sk_buff * skb)

release reference to header

Parameters

struct sk_buff * skb
buffer to operate on
int skb_shared(const struct sk_buff * skb)

is the buffer shared

Parameters

const struct sk_buff * skb
buffer to check

Description

Returns true if more than one person has a reference to this buffer.
struct sk_buff * skb_share_check(struct sk_buff * skb, gfp_t pri)

check if buffer is shared and if so clone it

Parameters

struct sk_buff * skb
buffer to check
gfp_t pri
priority for memory allocation

Description

If the buffer is shared the buffer is cloned and the old copy drops a reference. A new clone with a single reference is returned. If the buffer is not shared the original buffer is returned. When being called from interrupt status or with spinlocks held pri must be GFP_ATOMIC.

NULL is returned on a memory allocation failure.

struct sk_buff * skb_unshare(struct sk_buff * skb, gfp_t pri)

make a copy of a shared buffer

Parameters

struct sk_buff * skb
buffer to check
gfp_t pri
priority for memory allocation

Description

If the socket buffer is a clone then this function creates a new copy of the data, drops a reference count on the old copy and returns the new copy with the reference count at 1. If the buffer is not a clone the original buffer is returned. When called with a spinlock held or from interrupt state pri must be GFP_ATOMIC

NULL is returned on a memory allocation failure.

struct sk_buff * skb_peek(const struct sk_buff_head * list_)

peek at the head of an sk_buff_head

Parameters

const struct sk_buff_head * list_
list to peek at

Description

Peek an sk_buff. Unlike most other operations you _MUST_ be careful with this one. A peek leaves the buffer on the list and someone else may run off with it. You must hold the appropriate locks or have a private queue to do this.

Returns NULL for an empty list or a pointer to the head element. The reference count is not incremented and the reference is therefore volatile. Use with caution.

struct sk_buff * __skb_peek(const struct sk_buff_head * list_)

peek at the head of a non-empty sk_buff_head

Parameters

const struct sk_buff_head * list_
list to peek at

Description

Like skb_peek(), but the caller knows that the list is not empty.
struct sk_buff * skb_peek_next(struct sk_buff * skb, const struct sk_buff_head * list_)

peek skb following the given one from a queue

Parameters

struct sk_buff * skb
skb to start from
const struct sk_buff_head * list_
list to peek at

Description

Returns NULL when the end of the list is met or a pointer to the next element. The reference count is not incremented and the reference is therefore volatile. Use with caution.
struct sk_buff * skb_peek_tail(const struct sk_buff_head * list_)

peek at the tail of an sk_buff_head

Parameters

const struct sk_buff_head * list_
list to peek at

Description

Peek an sk_buff. Unlike most other operations you _MUST_ be careful with this one. A peek leaves the buffer on the list and someone else may run off with it. You must hold the appropriate locks or have a private queue to do this.

Returns NULL for an empty list or a pointer to the tail element. The reference count is not incremented and the reference is therefore volatile. Use with caution.

__u32 skb_queue_len(const struct sk_buff_head * list_)

get queue length

Parameters

const struct sk_buff_head * list_
list to measure

Description

Return the length of an sk_buff queue.
void __skb_queue_head_init(struct sk_buff_head * list)

initialize non-spinlock portions of sk_buff_head

Parameters

struct sk_buff_head * list
queue to initialize

Description

This initializes only the list and queue length aspects of an sk_buff_head object. This allows to initialize the list aspects of an sk_buff_head without reinitializing things like the spinlock. It can also be used for on-stack sk_buff_head objects where the spinlock is known to not be used.
void skb_queue_splice(const struct sk_buff_head * list, struct sk_buff_head * head)

join two skb lists, this is designed for stacks

Parameters

const struct sk_buff_head * list
the new list to add
struct sk_buff_head * head
the place to add it in the first list
void skb_queue_splice_init(struct sk_buff_head * list, struct sk_buff_head * head)

join two skb lists and reinitialise the emptied list

Parameters

struct sk_buff_head * list
the new list to add
struct sk_buff_head * head
the place to add it in the first list

Description

The list at list is reinitialised
void skb_queue_splice_tail(const struct sk_buff_head * list, struct sk_buff_head * head)

join two skb lists, each list being a queue

Parameters

const struct sk_buff_head * list
the new list to add
struct sk_buff_head * head
the place to add it in the first list
void skb_queue_splice_tail_init(struct sk_buff_head * list, struct sk_buff_head * head)

join two skb lists and reinitialise the emptied list

Parameters

struct sk_buff_head * list
the new list to add
struct sk_buff_head * head
the place to add it in the first list

Description

Each of the lists is a queue. The list at list is reinitialised
void __skb_queue_after(struct sk_buff_head * list, struct sk_buff * prev, struct sk_buff * newsk)

queue a buffer at the list head

Parameters

struct sk_buff_head * list
list to use
struct sk_buff * prev
place after this buffer
struct sk_buff * newsk
buffer to queue

Description

Queue a buffer int the middle of a list. This function takes no locks and you must therefore hold required locks before calling it.

A buffer cannot be placed on two lists at the same time.

void skb_queue_head(struct sk_buff_head * list, struct sk_buff * newsk)

queue a buffer at the list head

Parameters

struct sk_buff_head * list
list to use
struct sk_buff * newsk
buffer to queue

Description

Queue a buffer at the start of a list. This function takes no locks and you must therefore hold required locks before calling it.

A buffer cannot be placed on two lists at the same time.

void skb_queue_tail(struct sk_buff_head * list, struct sk_buff * newsk)

queue a buffer at the list tail

Parameters

struct sk_buff_head * list
list to use
struct sk_buff * newsk
buffer to queue

Description

Queue a buffer at the end of a list. This function takes no locks and you must therefore hold required locks before calling it.

A buffer cannot be placed on two lists at the same time.

struct sk_buff * skb_dequeue(struct sk_buff_head * list)

remove from the head of the queue

Parameters

struct sk_buff_head * list
list to dequeue from

Description

Remove the head of the list. This function does not take any locks so must be used with appropriate locks held only. The head item is returned or NULL if the list is empty.
struct sk_buff * skb_dequeue_tail(struct sk_buff_head * list)

remove from the tail of the queue

Parameters

struct sk_buff_head * list
list to dequeue from

Description

Remove the tail of the list. This function does not take any locks so must be used with appropriate locks held only. The tail item is returned or NULL if the list is empty.
void __skb_fill_page_desc(struct sk_buff * skb, int i, struct page * page, int off, int size)

initialise a paged fragment in an skb

Parameters

struct sk_buff * skb
buffer containing fragment to be initialised
int i
paged fragment index to initialise
struct page * page
the page to use for this fragment
int off
the offset to the data with page
int size
the length of the data

Description

Initialises the i’th fragment of skb to point to size bytes at offset off within page.

Does not take any additional reference on the fragment.

void skb_fill_page_desc(struct sk_buff * skb, int i, struct page * page, int off, int size)

initialise a paged fragment in an skb

Parameters

struct sk_buff * skb
buffer containing fragment to be initialised
int i
paged fragment index to initialise
struct page * page
the page to use for this fragment
int off
the offset to the data with page
int size
the length of the data

Description

As per __skb_fill_page_desc() – initialises the i’th fragment of skb to point to size bytes at offset off within page. In addition updates skb such that i is the last fragment.

Does not take any additional reference on the fragment.

unsigned int skb_headroom(const struct sk_buff * skb)

bytes at buffer head

Parameters

const struct sk_buff * skb
buffer to check

Description

Return the number of bytes of free space at the head of an sk_buff.
int skb_tailroom(const struct sk_buff * skb)

bytes at buffer end

Parameters

const struct sk_buff * skb
buffer to check

Description

Return the number of bytes of free space at the tail of an sk_buff
int skb_availroom(const struct sk_buff * skb)

bytes at buffer end

Parameters

const struct sk_buff * skb
buffer to check

Description

Return the number of bytes of free space at the tail of an sk_buff allocated by sk_stream_alloc()
void skb_reserve(struct sk_buff * skb, int len)

adjust headroom

Parameters

struct sk_buff * skb
buffer to alter
int len
bytes to move

Description

Increase the headroom of an empty sk_buff by reducing the tail room. This is only allowed for an empty buffer.
void skb_tailroom_reserve(struct sk_buff * skb, unsigned int mtu, unsigned int needed_tailroom)

adjust reserved_tailroom

Parameters

struct sk_buff * skb
buffer to alter
unsigned int mtu
maximum amount of headlen permitted
unsigned int needed_tailroom
minimum amount of reserved_tailroom

Description

Set reserved_tailroom so that headlen can be as large as possible but not larger than mtu and tailroom cannot be smaller than needed_tailroom. The required headroom should already have been reserved before using this function.
void pskb_trim_unique(struct sk_buff * skb, unsigned int len)

remove end from a paged unique (not cloned) buffer

Parameters

struct sk_buff * skb
buffer to alter
unsigned int len
new length

Description

This is identical to pskb_trim except that the caller knows that the skb is not cloned so we should never get an error due to out- of-memory.
void skb_orphan(struct sk_buff * skb)

orphan a buffer

Parameters

struct sk_buff * skb
buffer to orphan

Description

If a buffer currently has an owner then we call the owner’s destructor function and make the skb unowned. The buffer continues to exist but is no longer charged to its former owner.
int skb_orphan_frags(struct sk_buff * skb, gfp_t gfp_mask)

orphan the frags contained in a buffer

Parameters

struct sk_buff * skb
buffer to orphan frags from
gfp_t gfp_mask
allocation mask for replacement pages

Description

For each frag in the SKB which needs a destructor (i.e. has an owner) create a copy of that frag and release the original page by calling the destructor.
void skb_queue_purge(struct sk_buff_head * list)

empty a list

Parameters

struct sk_buff_head * list
list to empty

Description

Delete all buffers on an sk_buff list. Each buffer is removed from the list and one reference dropped. This function does not take the list lock and the caller must hold the relevant locks to use it.
struct sk_buff * netdev_alloc_skb(struct net_device * dev, unsigned int length)

allocate an skbuff for rx on a specific device

Parameters

struct net_device * dev
network device to receive on
unsigned int length
length to allocate

Description

Allocate a new sk_buff and assign it a usage count of one. The buffer has unspecified headroom built in. Users should allocate the headroom they think they need without accounting for the built in space. The built in space is used for optimisations.

NULL is returned if there is no free memory. Although this function allocates memory it can be called from an interrupt.

struct page * __dev_alloc_pages(gfp_t gfp_mask, unsigned int order)

allocate page for network Rx

Parameters

gfp_t gfp_mask
allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
unsigned int order
size of the allocation

Description

Allocate a new page.

NULL is returned if there is no free memory.

struct page * __dev_alloc_page(gfp_t gfp_mask)

allocate a page for network Rx

Parameters

gfp_t gfp_mask
allocation priority. Set __GFP_NOMEMALLOC if not for network Rx

Description

Allocate a new page.

NULL is returned if there is no free memory.

void skb_propagate_pfmemalloc(struct page * page, struct sk_buff * skb)

Propagate pfmemalloc if skb is allocated after RX page

Parameters

struct page * page
The page that was allocated from skb_alloc_page
struct sk_buff * skb
The skb that may need pfmemalloc set
struct page * skb_frag_page(const skb_frag_t * frag)

retrieve the page referred to by a paged fragment

Parameters

const skb_frag_t * frag
the paged fragment

Description

Returns the struct page associated with frag.

void __skb_frag_ref(skb_frag_t * frag)

take an addition reference on a paged fragment.

Parameters

skb_frag_t * frag
the paged fragment

Description

Takes an additional reference on the paged fragment frag.

void skb_frag_ref(struct sk_buff * skb, int f)

take an addition reference on a paged fragment of an skb.

Parameters

struct sk_buff * skb
the buffer
int f
the fragment offset.

Description

Takes an additional reference on the f’th paged fragment of skb.

void __skb_frag_unref(skb_frag_t * frag)

release a reference on a paged fragment.

Parameters

skb_frag_t * frag
the paged fragment

Description

Releases a reference on the paged fragment frag.

void skb_frag_unref(struct sk_buff * skb, int f)

release a reference on a paged fragment of an skb.

Parameters

struct sk_buff * skb
the buffer
int f
the fragment offset

Description

Releases a reference on the f’th paged fragment of skb.

void * skb_frag_address(const skb_frag_t * frag)

gets the address of the data contained in a paged fragment

Parameters

const skb_frag_t * frag
the paged fragment buffer

Description

Returns the address of the data within frag. The page must already be mapped.

void * skb_frag_address_safe(const skb_frag_t * frag)

gets the address of the data contained in a paged fragment

Parameters

const skb_frag_t * frag
the paged fragment buffer

Description

Returns the address of the data within frag. Checks that the page is mapped and returns NULL otherwise.

void __skb_frag_set_page(skb_frag_t * frag, struct page * page)

sets the page contained in a paged fragment

Parameters

skb_frag_t * frag
the paged fragment
struct page * page
the page to set

Description

Sets the fragment frag to contain page.

void skb_frag_set_page(struct sk_buff * skb, int f, struct page * page)

sets the page contained in a paged fragment of an skb

Parameters

struct sk_buff * skb
the buffer
int f
the fragment offset
struct page * page
the page to set

Description

Sets the f’th fragment of skb to contain page.

dma_addr_t skb_frag_dma_map(struct device * dev, const skb_frag_t * frag, size_t offset, size_t size, enum dma_data_direction dir)

maps a paged fragment via the DMA API

Parameters

struct device * dev
the device to map the fragment to
const skb_frag_t * frag
the paged fragment to map
size_t offset
the offset within the fragment (starting at the fragment’s own offset)
size_t size
the number of bytes to map
enum dma_data_direction dir
the direction of the mapping (PCI_DMA_*)

Description

Maps the page associated with frag to device.

int skb_clone_writable(const struct sk_buff * skb, unsigned int len)

is the header of a clone writable

Parameters

const struct sk_buff * skb
buffer to check
unsigned int len
length up to which to write

Description

Returns true if modifying the header part of the cloned buffer does not requires the data to be copied.
int skb_cow(struct sk_buff * skb, unsigned int headroom)

copy header of skb when it is required

Parameters

struct sk_buff * skb
buffer to cow
unsigned int headroom
needed headroom

Description

If the skb passed lacks sufficient headroom or its data part is shared, data is reallocated. If reallocation fails, an error is returned and original skb is not changed.

The result is skb with writable area skb->head…skb->tail and at least headroom of space at head.

int skb_cow_head(struct sk_buff * skb, unsigned int headroom)

skb_cow but only making the head writable

Parameters

struct sk_buff * skb
buffer to cow
unsigned int headroom
needed headroom

Description

This function is identical to skb_cow except that we replace the skb_cloned check by skb_header_cloned. It should be used when you only need to push on some header and do not need to modify the data.
int skb_padto(struct sk_buff * skb, unsigned int len)

pad an skbuff up to a minimal size

Parameters

struct sk_buff * skb
buffer to pad
unsigned int len
minimal length

Description

Pads up a buffer to ensure the trailing bytes exist and are blanked. If the buffer already contains sufficient data it is untouched. Otherwise it is extended. Returns zero on success. The skb is freed on error.
int __skb_put_padto(struct sk_buff * skb, unsigned int len, bool free_on_error)

increase size and pad an skbuff up to a minimal size

Parameters

struct sk_buff * skb
buffer to pad
unsigned int len
minimal length
bool free_on_error
free buffer on error

Description

Pads up a buffer to ensure the trailing bytes exist and are blanked. If the buffer already contains sufficient data it is untouched. Otherwise it is extended. Returns zero on success. The skb is freed on error if free_on_error is true.
int skb_put_padto(struct sk_buff * skb, unsigned int len)

increase size and pad an skbuff up to a minimal size

Parameters

struct sk_buff * skb
buffer to pad
unsigned int len
minimal length

Description

Pads up a buffer to ensure the trailing bytes exist and are blanked. If the buffer already contains sufficient data it is untouched. Otherwise it is extended. Returns zero on success. The skb is freed on error.
int skb_linearize(struct sk_buff * skb)

convert paged skb to linear one

Parameters

struct sk_buff * skb
buffer to linarize

Description

If there is no free memory -ENOMEM is returned, otherwise zero is returned and the old skb data released.
bool skb_has_shared_frag(const struct sk_buff * skb)

can any frag be overwritten

Parameters

const struct sk_buff * skb
buffer to test

Description

Return true if the skb has at least one frag that might be modified by an external entity (as in vmsplice()/sendfile())

int skb_linearize_cow(struct sk_buff * skb)

make sure skb is linear and writable

Parameters

struct sk_buff * skb
buffer to process

Description

If there is no free memory -ENOMEM is returned, otherwise zero is returned and the old skb data released.
void skb_postpull_rcsum(struct sk_buff * skb, const void * start, unsigned int len)

update checksum for received skb after pull

Parameters

struct sk_buff * skb
buffer to update
const void * start
start of data before pull
unsigned int len
length of data pulled

Description

After doing a pull on a received packet, you need to call this to update the CHECKSUM_COMPLETE checksum, or set ip_summed to CHECKSUM_NONE so that it can be recomputed from scratch.
void skb_postpush_rcsum(struct sk_buff * skb, const void * start, unsigned int len)

update checksum for received skb after push

Parameters

struct sk_buff * skb
buffer to update
const void * start
start of data after push
unsigned int len
length of data pushed

Description

After doing a push on a received packet, you need to call this to update the CHECKSUM_COMPLETE checksum.
void * skb_push_rcsum(struct sk_buff * skb, unsigned int len)

push skb and update receive checksum

Parameters

struct sk_buff * skb
buffer to update
unsigned int len
length of data pulled

Description

This function performs an skb_push on the packet and updates the CHECKSUM_COMPLETE checksum. It should be used on receive path processing instead of skb_push unless you know that the checksum difference is zero (e.g., a valid IP header) or you are setting ip_summed to CHECKSUM_NONE.
int pskb_trim_rcsum(struct sk_buff * skb, unsigned int len)

trim received skb and update checksum

Parameters

struct sk_buff * skb
buffer to trim
unsigned int len
new length

Description

This is exactly the same as pskb_trim except that it ensures the checksum of received packets are still valid after the operation.
bool skb_needs_linearize(struct sk_buff * skb, netdev_features_t features)

check if we need to linearize a given skb depending on the given device features.

Parameters

struct sk_buff * skb
socket buffer to check
netdev_features_t features
net device features

Description

Returns true if either: 1. skb has frag_list and the device doesn’t support FRAGLIST, or 2. skb is fragmented and the device does not support SG.
void skb_get_timestamp(const struct sk_buff * skb, struct timeval * stamp)

get timestamp from a skb

Parameters

const struct sk_buff * skb
skb to get stamp from
struct timeval * stamp
pointer to struct timeval to store stamp in

Description

Timestamps are stored in the skb as offsets to a base timestamp. This function converts the offset back to a struct timeval and stores it in stamp.
void skb_complete_tx_timestamp(struct sk_buff * skb, struct skb_shared_hwtstamps * hwtstamps)

deliver cloned skb with tx timestamps

Parameters

struct sk_buff * skb
clone of the the original outgoing packet
struct skb_shared_hwtstamps * hwtstamps
hardware time stamps

Description

PHY drivers may accept clones of transmitted packets for timestamping via their phy_driver.txtstamp method. These drivers must call this function to return the skb back to the stack with a timestamp.

void skb_tstamp_tx(struct sk_buff * orig_skb, struct skb_shared_hwtstamps * hwtstamps)

queue clone of skb with send time stamps

Parameters

struct sk_buff * orig_skb
the original outgoing packet
struct skb_shared_hwtstamps * hwtstamps
hardware time stamps, may be NULL if not available

Description

If the skb has a socket associated, then this function clones the skb (thus sharing the actual data and optional structures), stores the optional hardware time stamping information (if non NULL) or generates a software time stamp (otherwise), then queues the clone to the error queue of the socket. Errors are silently ignored.

void skb_tx_timestamp(struct sk_buff * skb)

Driver hook for transmit timestamping

Parameters

struct sk_buff * skb
A socket buffer.

Description

Ethernet MAC Drivers should call this function in their hard_xmit() function immediately before giving the sk_buff to the MAC hardware.

Specifically, one should make absolutely sure that this function is called before TX completion of this packet can trigger. Otherwise the packet could potentially already be freed.

void skb_complete_wifi_ack(struct sk_buff * skb, bool acked)

deliver skb with wifi status

Parameters

struct sk_buff * skb
the original outgoing packet
bool acked
ack status
__sum16 skb_checksum_complete(struct sk_buff * skb)

Calculate checksum of an entire packet

Parameters

struct sk_buff * skb
packet to process

Description

This function calculates the checksum over the entire packet plus the value of skb->csum. The latter can be used to supply the checksum of a pseudo header as used by TCP/UDP. It returns the checksum.

For protocols that contain complete checksums such as ICMP/TCP/UDP, this function can be used to verify that checksum on received packets. In that case the function should return zero if the checksum is correct. In particular, this function will return zero if skb->ip_summed is CHECKSUM_UNNECESSARY which indicates that the hardware has already verified the correctness of the checksum.

void skb_checksum_none_assert(const struct sk_buff * skb)

make sure skb ip_summed is CHECKSUM_NONE

Parameters

const struct sk_buff * skb
skb to check

Description

fresh skbs have their ip_summed set to CHECKSUM_NONE. Instead of forcing ip_summed to CHECKSUM_NONE, we can use this helper, to document places where we make this assertion.

bool skb_head_is_locked(const struct sk_buff * skb)

Determine if the skb->head is locked down

Parameters

const struct sk_buff * skb
skb to check

Description

The head on skbs build around a head frag can be removed if they are not cloned. This function returns true if the skb head is locked down due to either being allocated via kmalloc, or by being a clone with multiple references to the head.

struct sock_common

minimal network layer representation of sockets

Definition

struct sock_common {
  union {
    __addrpair skc_addrpair;
    struct {
      __be32 skc_daddr;
      __be32 skc_rcv_saddr;
    };
  };
  union {
    unsigned int    skc_hash;
    __u16 skc_u16hashes[2];
  };
  union {
    __portpair skc_portpair;
    struct {
      __be16 skc_dport;
      __u16 skc_num;
    };
  };
  unsigned short          skc_family;
  volatile unsigned char  skc_state;
  unsigned char           skc_reuse:4;
  unsigned char           skc_reuseport:1;
  unsigned char           skc_ipv6only:1;
  unsigned char           skc_net_refcnt:1;
  int skc_bound_dev_if;
  union {
    struct hlist_node       skc_bind_node;
    struct hlist_node       skc_portaddr_node;
  };
  struct proto            *skc_prot;
  possible_net_t skc_net;
#if IS_ENABLED(CONFIG_IPV6);
  struct in6_addr         skc_v6_daddr;
  struct in6_addr         skc_v6_rcv_saddr;
#endif;
  atomic64_t skc_cookie;
  union {
    unsigned long   skc_flags;
    struct sock     *skc_listener;
    struct inet_timewait_death_row *skc_tw_dr;
  };
  union {
    struct hlist_node       skc_node;
    struct hlist_nulls_node skc_nulls_node;
  };
  unsigned short          skc_tx_queue_mapping;
#ifdef CONFIG_XPS;
  unsigned short          skc_rx_queue_mapping;
#endif;
  union {
    int skc_incoming_cpu;
    u32 skc_rcv_wnd;
    u32 skc_tw_rcv_nxt;
  };
  refcount_t skc_refcnt;
};

Members

{unnamed_union}
anonymous
{unnamed_struct}
anonymous
skc_daddr
Foreign IPv4 addr
skc_rcv_saddr
Bound local IPv4 addr
{unnamed_union}
anonymous
skc_hash
hash value used with various protocol lookup tables
skc_u16hashes
two u16 hash values used by UDP lookup tables
{unnamed_union}
anonymous
{unnamed_struct}
anonymous
skc_dport
placeholder for inet_dport/tw_dport
skc_num
placeholder for inet_num/tw_num
skc_family
network address family
skc_state
Connection state
skc_reuse
SO_REUSEADDR setting
skc_reuseport
SO_REUSEPORT setting
skc_bound_dev_if
bound device index if != 0
{unnamed_union}
anonymous
skc_bind_node
bind hash linkage for various protocol lookup tables
skc_portaddr_node
second hash linkage for UDP/UDP-Lite protocol
skc_prot
protocol handlers inside a network family
skc_net
reference to the network namespace of this socket
{unnamed_union}
anonymous
skc_flags
place holder for sk_flags SO_LINGER (l_onoff), SO_BROADCAST, SO_KEEPALIVE, SO_OOBINLINE settings, SO_TIMESTAMPING settings
{unnamed_union}
anonymous
skc_node
main hash linkage for various protocol lookup tables
skc_nulls_node
main hash linkage for TCP/UDP/UDP-Lite protocol
skc_tx_queue_mapping
tx queue number for this connection
skc_rx_queue_mapping
rx queue number for this connection
{unnamed_union}
anonymous
skc_incoming_cpu
record/match cpu processing incoming packets
skc_refcnt
reference count

Description

This is the minimal network layer representation of sockets, the header for struct sock and struct inet_timewait_sock.
struct sock

network layer representation of sockets

Definition

struct sock {
  struct sock_common      __sk_common;
#define sk_node                 __sk_common.skc_node;
#define sk_nulls_node           __sk_common.skc_nulls_node;
#define sk_refcnt               __sk_common.skc_refcnt;
#define sk_tx_queue_mapping     __sk_common.skc_tx_queue_mapping;
#ifdef CONFIG_XPS;
#define sk_rx_queue_mapping     __sk_common.skc_rx_queue_mapping;
#endif;
#define sk_dontcopy_begin       __sk_common.skc_dontcopy_begin;
#define sk_dontcopy_end         __sk_common.skc_dontcopy_end;
#define sk_hash                 __sk_common.skc_hash;
#define sk_portpair             __sk_common.skc_portpair;
#define sk_num                  __sk_common.skc_num;
#define sk_dport                __sk_common.skc_dport;
#define sk_addrpair             __sk_common.skc_addrpair;
#define sk_daddr                __sk_common.skc_daddr;
#define sk_rcv_saddr            __sk_common.skc_rcv_saddr;
#define sk_family               __sk_common.skc_family;
#define sk_state                __sk_common.skc_state;
#define sk_reuse                __sk_common.skc_reuse;
#define sk_reuseport            __sk_common.skc_reuseport;
#define sk_ipv6only             __sk_common.skc_ipv6only;
#define sk_net_refcnt           __sk_common.skc_net_refcnt;
#define sk_bound_dev_if         __sk_common.skc_bound_dev_if;
#define sk_bind_node            __sk_common.skc_bind_node;
#define sk_prot                 __sk_common.skc_prot;
#define sk_net                  __sk_common.skc_net;
#define sk_v6_daddr             __sk_common.skc_v6_daddr;
#define sk_v6_rcv_saddr __sk_common.skc_v6_rcv_saddr;
#define sk_cookie               __sk_common.skc_cookie;
#define sk_incoming_cpu         __sk_common.skc_incoming_cpu;
#define sk_flags                __sk_common.skc_flags;
#define sk_rxhash               __sk_common.skc_rxhash;
  socket_lock_t sk_lock;
  atomic_t sk_drops;
  int sk_rcvlowat;
  struct sk_buff_head     sk_error_queue;
  struct sk_buff_head     sk_receive_queue;
  struct {
    atomic_t rmem_alloc;
    int len;
    struct sk_buff  *head;
    struct sk_buff  *tail;
  } sk_backlog;
#define sk_rmem_alloc sk_backlog.rmem_alloc;
  int sk_forward_alloc;
#ifdef CONFIG_NET_RX_BUSY_POLL;
  unsigned int            sk_ll_usec;
  unsigned int            sk_napi_id;
#endif;
  int sk_rcvbuf;
  struct sk_filter __rcu  *sk_filter;
  union {
    struct socket_wq __rcu  *sk_wq;
    struct socket_wq        *sk_wq_raw;
  };
#ifdef CONFIG_XFRM;
  struct xfrm_policy __rcu *sk_policy[2];
#endif;
  struct dst_entry        *sk_rx_dst;
  struct dst_entry __rcu  *sk_dst_cache;
  atomic_t sk_omem_alloc;
  int sk_sndbuf;
  int sk_wmem_queued;
  refcount_t sk_wmem_alloc;
  unsigned long           sk_tsq_flags;
  union {
    struct sk_buff  *sk_send_head;
    struct rb_root  tcp_rtx_queue;
  };
  struct sk_buff_head     sk_write_queue;
  __s32 sk_peek_off;
  int sk_write_pending;
  __u32 sk_dst_pending_confirm;
  u32 sk_pacing_status;
  long sk_sndtimeo;
  struct timer_list       sk_timer;
  __u32 sk_priority;
  __u32 sk_mark;
  unsigned long           sk_pacing_rate;
  unsigned long           sk_max_pacing_rate;
  struct page_frag        sk_frag;
  netdev_features_t sk_route_caps;
  netdev_features_t sk_route_nocaps;
  netdev_features_t sk_route_forced_caps;
  int sk_gso_type;
  unsigned int            sk_gso_max_size;
  gfp_t sk_allocation;
  __u32 sk_txhash;
  unsigned int            __sk_flags_offset[0];
#ifdef __BIG_ENDIAN_BITFIELD;
#define SK_FL_PROTO_SHIFT  16;
#define SK_FL_PROTO_MASK   0x00ff0000;
#define SK_FL_TYPE_SHIFT   0;
#define SK_FL_TYPE_MASK    0x0000ffff;
#else;
#define SK_FL_PROTO_SHIFT  8;
#define SK_FL_PROTO_MASK   0x0000ff00;
#define SK_FL_TYPE_SHIFT   16;
#define SK_FL_TYPE_MASK    0xffff0000;
#endif;
  unsigned int            sk_padding : 1,sk_kern_sock : 1,sk_no_check_tx : 1,sk_no_check_rx : 1,sk_userlocks : 4,sk_protocol  : 8, sk_type      : 16;
#define SK_PROTOCOL_MAX U8_MAX;
  u16 sk_gso_max_segs;
  u8 sk_pacing_shift;
  unsigned long           sk_lingertime;
  struct proto            *sk_prot_creator;
  rwlock_t sk_callback_lock;
  int sk_err, sk_err_soft;
  u32 sk_ack_backlog;
  u32 sk_max_ack_backlog;
  kuid_t sk_uid;
  struct pid              *sk_peer_pid;
  const struct cred       *sk_peer_cred;
  long sk_rcvtimeo;
  ktime_t sk_stamp;
  u16 sk_tsflags;
  u8 sk_shutdown;
  u32 sk_tskey;
  atomic_t sk_zckey;
  u8 sk_clockid;
  u8 sk_txtime_deadline_mode : 1,sk_txtime_report_errors : 1, sk_txtime_unused : 6;
  struct socket           *sk_socket;
  void *sk_user_data;
#ifdef CONFIG_SECURITY;
  void *sk_security;
#endif;
  struct sock_cgroup_data sk_cgrp_data;
  struct mem_cgroup       *sk_memcg;
  void (*sk_state_change)(struct sock *sk);
  void (*sk_data_ready)(struct sock *sk);
  void (*sk_write_space)(struct sock *sk);
  void (*sk_error_report)(struct sock *sk);
  int (*sk_backlog_rcv)(struct sock *sk, struct sk_buff *skb);
#ifdef CONFIG_SOCK_VALIDATE_XMIT;
  struct sk_buff*         (*sk_validate_xmit_skb)(struct sock *sk,struct net_device *dev, struct sk_buff *skb);
#endif;
  void (*sk_destruct)(struct sock *sk);
  struct sock_reuseport __rcu     *sk_reuseport_cb;
  struct rcu_head         sk_rcu;
};

Members

__sk_common
shared layout with inet_timewait_sock
sk_lock
synchronizer
sk_drops
raw/udp drops counter
sk_rcvlowat
SO_RCVLOWAT setting
sk_error_queue
rarely used
sk_receive_queue
incoming packets
sk_backlog
always used with the per-socket spinlock held
sk_forward_alloc
space allocated forward
sk_ll_usec
usecs to busypoll when there is no data
sk_napi_id
id of the last napi context to receive data for sk
sk_rcvbuf
size of receive buffer in bytes
sk_filter
socket filtering instructions
{unnamed_union}
anonymous
sk_wq
sock wait queue and async head
sk_policy
flow policy
sk_rx_dst
receive input route used by early demux
sk_dst_cache
destination cache
sk_omem_alloc
“o” is “option” or “other”
sk_sndbuf
size of send buffer in bytes
sk_wmem_queued
persistent queue size
sk_wmem_alloc
transmit queue bytes committed
sk_tsq_flags
TCP Small Queues flags
{unnamed_union}
anonymous
sk_send_head
front of stuff to transmit
sk_write_queue
Packet sending queue
sk_peek_off
current peek_offset value
sk_write_pending
a write to stream socket waits to start
sk_dst_pending_confirm
need to confirm neighbour
sk_pacing_status
Pacing status (requested, handled by sch_fq)
sk_sndtimeo
SO_SNDTIMEO setting
sk_timer
sock cleanup timer
sk_priority
SO_PRIORITY setting
sk_mark
generic packet mark
sk_pacing_rate
Pacing rate (if supported by transport/packet scheduler)
sk_max_pacing_rate
Maximum pacing rate (SO_MAX_PACING_RATE)
sk_frag
cached page frag
sk_route_caps
route capabilities (e.g. NETIF_F_TSO)
sk_route_nocaps
forbidden route capabilities (e.g NETIF_F_GSO_MASK)
sk_gso_type
GSO type (e.g. SKB_GSO_TCPV4)
sk_gso_max_size
Maximum GSO segment size to build
sk_allocation
allocation mode
sk_txhash
computed flow hash for use on transmit
__sk_flags_offset
empty field used to determine location of bitfield
sk_padding
unused element for alignment
sk_kern_sock
True if sock is using kernel lock classes
sk_no_check_tx
SO_NO_CHECK setting, set checksum in TX packets
sk_no_check_rx
allow zero checksum in RX packets
sk_userlocks
SO_SNDBUF and SO_RCVBUF settings
sk_protocol
which protocol this socket belongs in this network family
sk_type
socket type (SOCK_STREAM, etc)
sk_gso_max_segs
Maximum number of GSO segments
sk_pacing_shift
scaling factor for TCP Small Queues
sk_lingertime
SO_LINGER l_linger setting
sk_prot_creator
sk_prot of original sock creator (see ipv6_setsockopt, IPV6_ADDRFORM for instance)
sk_callback_lock
used with the callbacks in the end of this struct
sk_err
last error
sk_err_soft
errors that don’t cause failure but are the cause of a persistent failure not just ‘timed out’
sk_ack_backlog
current listen backlog
sk_max_ack_backlog
listen backlog set in listen()
sk_uid
user id of owner
sk_peer_pid
struct pid for this socket’s peer
sk_peer_cred
SO_PEERCRED setting
sk_rcvtimeo
SO_RCVTIMEO setting
sk_stamp
time stamp of last packet received
sk_tsflags
SO_TIMESTAMPING socket options
sk_shutdown
mask of SEND_SHUTDOWN and/or RCV_SHUTDOWN
sk_tskey
counter to disambiguate concurrent tstamp requests
sk_zckey
counter to order MSG_ZEROCOPY notifications
sk_clockid
clockid used by time-based scheduling (SO_TXTIME)
sk_txtime_deadline_mode
set deadline mode for SO_TXTIME
sk_txtime_unused
unused txtime flags
sk_socket
Identd and reporting IO signals
sk_user_data
RPC layer private data
sk_security
used by security modules
sk_cgrp_data
cgroup data for this cgroup
sk_memcg
this socket’s memory cgroup association
sk_state_change
callback to indicate change in the state of the sock
sk_data_ready
callback to indicate there is data to be processed
sk_write_space
callback to indicate there is bf sending space available
sk_error_report
callback to indicate errors (e.g. MSG_ERRQUEUE)
sk_backlog_rcv
callback to process the backlog
sk_destruct
called at sock freeing time, i.e. when all refcnt == 0
sk_reuseport_cb
reuseport group container
sk_rcu
used during RCU grace period
sk_for_each_entry_offset_rcu(tpos, pos, head, offset)

iterate over a list at a given struct offset

Parameters

tpos
the type * to use as a loop cursor.
pos
the struct hlist_node to use as a loop cursor.
head
the head for your list.
offset
offset of hlist_node within the struct.
void unlock_sock_fast(struct sock * sk, bool slow)

complement of lock_sock_fast

Parameters

struct sock * sk
socket
bool slow
slow mode

Description

fast unlock socket for user context. If slow mode is on, we call regular release_sock()

int sk_wmem_alloc_get(const struct sock * sk)

returns write allocations

Parameters

const struct sock * sk
socket

Description

Returns sk_wmem_alloc minus initial offset of one

int sk_rmem_alloc_get(const struct sock * sk)

returns read allocations

Parameters

const struct sock * sk
socket

Description

Returns sk_rmem_alloc

bool sk_has_allocations(const struct sock * sk)

check if allocations are outstanding

Parameters

const struct sock * sk
socket

Description

Returns true if socket has write or read allocations

bool skwq_has_sleeper(struct socket_wq * wq)

check if there are any waiting processes

Parameters

struct socket_wq * wq
struct socket_wq

Description

Returns true if socket_wq has waiting processes

The purpose of the skwq_has_sleeper and sock_poll_wait is to wrap the memory barrier call. They were added due to the race found within the tcp code.

Consider following tcp code paths:

CPU1                CPU2
sys_select          receive packet
...                 ...
__add_wait_queue    update tp->rcv_nxt
...                 ...
tp->rcv_nxt check   sock_def_readable
...                 {
schedule               rcu_read_lock();
                       wq = rcu_dereference(sk->sk_wq);
                       if (wq && waitqueue_active(&wq->wait))
                           wake_up_interruptible(&wq->wait)
                       ...
                    }

The race for tcp fires when the __add_wait_queue changes done by CPU1 stay in its cache, and so does the tp->rcv_nxt update on CPU2 side. The CPU1 could then endup calling schedule and sleep forever if there are no more data on the socket.

void sock_poll_wait(struct file * filp, struct socket * sock, poll_table * p)

place memory barrier behind the poll_wait call.

Parameters

struct file * filp
file
struct socket * sock
socket to wait on
poll_table * p
poll_table

Description

See the comments in the wq_has_sleeper function.

Do not derive sock from filp->private_data here. An SMC socket establishes an internal TCP socket that is used in the fallback case. All socket operations on the SMC socket are then forwarded to the TCP socket. In case of poll, the filp->private_data pointer references the SMC socket because the TCP socket has no file assigned.

struct page_frag * sk_page_frag(struct sock * sk)

return an appropriate page_frag

Parameters

struct sock * sk
socket

Description

If socket allocation mode allows current thread to sleep, it means its safe to use the per task page_frag instead of the per socket one.

void sock_tx_timestamp(const struct sock * sk, __u16 tsflags, __u8 * tx_flags)

checks whether the outgoing packet is to be time stamped

Parameters

const struct sock * sk
socket sending this packet
__u16 tsflags
timestamping flags to use
__u8 * tx_flags
completed with instructions for time stamping

Note

callers should take care of initial *tx_flags value (usually 0)

void sk_eat_skb(struct sock * sk, struct sk_buff * skb)

Release a skb if it is no longer needed

Parameters

struct sock * sk
socket to eat this skb from
struct sk_buff * skb
socket buffer to eat

Description

This routine must be called with interrupts disabled or with the socket locked so that the sk_buff queue operation is ok.

struct socket * sockfd_lookup(int fd, int * err)

Go from a file number to its socket slot

Parameters

int fd
file handle
int * err
pointer to an error code return

Description

The file handle passed in is locked and the socket it is bound to is returned. If an error occurs the err pointer is overwritten with a negative errno code and NULL is returned. The function checks for both invalid handles and passing a handle which is not a socket.

On a success the socket object pointer is returned.

struct socket * sock_alloc(void)

allocate a socket

Parameters

void
no arguments

Description

Allocate a new inode and socket object. The two are bound together and initialised. The socket is then returned. If we are out of inodes NULL is returned.
int kernel_recvmsg(struct socket * sock, struct msghdr * msg, struct kvec * vec, size_t num, size_t size, int flags)

Receive a message from a socket (kernel space)

Parameters

struct socket * sock
The socket to receive the message from
struct msghdr * msg
Received message
struct kvec * vec
Input s/g array for message data
size_t num
Size of input s/g array
size_t size
Number of bytes to read
int flags
Message flags (MSG_DONTWAIT, etc…)

Description

On return the msg structure contains the scatter/gather array passed in the vec argument. The array is modified so that it consists of the unfilled portion of the original array.

The returned value is the total number of bytes received, or an error.

int sock_register(const struct net_proto_family * ops)

add a socket protocol handler

Parameters

const struct net_proto_family * ops
description of protocol

Description

This function is called by a protocol handler that wants to advertise its address family, and have it linked into the socket interface. The value ops->family corresponds to the socket system call protocol family.
void sock_unregister(int family)

remove a protocol handler

Parameters

int family
protocol family to remove

Description

This function is called by a protocol handler that wants to remove its address family, and have it unlinked from the new socket creation.

If protocol handler is a module, then it can use module reference counts to protect against new references. If protocol handler is not a module then it needs to provide its own protection in the ops->create routine.

struct sk_buff * __alloc_skb(unsigned int size, gfp_t gfp_mask, int flags, int node)

allocate a network buffer

Parameters

unsigned int size
size to allocate
gfp_t gfp_mask
allocation mask
int flags
If SKB_ALLOC_FCLONE is set, allocate from fclone cache instead of head cache and allocate a cloned (child) skb. If SKB_ALLOC_RX is set, __GFP_MEMALLOC will be used for allocations in case the data is required for writeback
int node
numa node to allocate memory on

Description

Allocate a new sk_buff. The returned buffer has no headroom and a tail room of at least size bytes. The object has a reference count of one. The return is the buffer. On a failure the return is NULL.

Buffers may only be allocated from interrupts using a gfp_mask of GFP_ATOMIC.

void * netdev_alloc_frag(unsigned int fragsz)

allocate a page fragment

Parameters

unsigned int fragsz
fragment size

Description

Allocates a frag from a page for receive buffer. Uses GFP_ATOMIC allocations.

struct sk_buff * __netdev_alloc_skb(struct net_device * dev, unsigned int len, gfp_t gfp_mask)

allocate an skbuff for rx on a specific device

Parameters

struct net_device * dev
network device to receive on
unsigned int len
length to allocate
gfp_t gfp_mask
get_free_pages mask, passed to alloc_skb

Description

Allocate a new sk_buff and assign it a usage count of one. The buffer has NET_SKB_PAD headroom built in. Users should allocate the headroom they think they need without accounting for the built in space. The built in space is used for optimisations.

NULL is returned if there is no free memory.

struct sk_buff * __napi_alloc_skb(struct napi_struct * napi, unsigned int len, gfp_t gfp_mask)

allocate skbuff for rx in a specific NAPI instance

Parameters

struct napi_struct * napi
napi instance this buffer was allocated for
unsigned int len
length to allocate
gfp_t gfp_mask
get_free_pages mask, passed to alloc_skb and alloc_pages

Description

Allocate a new sk_buff for use in NAPI receive. This buffer will attempt to allocate the head from a special reserved region used only for NAPI Rx allocation. By doing this we can save several CPU cycles by avoiding having to disable and re-enable IRQs.

NULL is returned if there is no free memory.

void __kfree_skb(struct sk_buff * skb)

private function

Parameters

struct sk_buff * skb
buffer

Description

Free an sk_buff. Release anything attached to the buffer. Clean the state. This is an internal helper function. Users should always call kfree_skb
void kfree_skb(struct sk_buff * skb)

free an sk_buff

Parameters

struct sk_buff * skb
buffer to free

Description

Drop a reference to the buffer and free it if the usage count has hit zero.
void skb_tx_error(struct sk_buff * skb)

report an sk_buff xmit error

Parameters

struct sk_buff * skb
buffer that triggered an error

Description

Report xmit error if a device callback is tracking this skb. skb must be freed afterwards.
void consume_skb(struct sk_buff * skb)

free an skbuff

Parameters

struct sk_buff * skb
buffer to free

Description

Drop a ref to the buffer and free it if the usage count has hit zero Functions identically to kfree_skb, but kfree_skb assumes that the frame is being dropped after a failure and notes that
struct sk_buff * skb_morph(struct sk_buff * dst, struct sk_buff * src)

morph one skb into another

Parameters

struct sk_buff * dst
the skb to receive the contents
struct sk_buff * src
the skb to supply the contents

Description

This is identical to skb_clone except that the target skb is supplied by the user.

The target skb is returned upon exit.

int skb_copy_ubufs(struct sk_buff * skb, gfp_t gfp_mask)

copy userspace skb frags buffers to kernel

Parameters

struct sk_buff * skb
the skb to modify
gfp_t gfp_mask
allocation priority

Description

This must be called on SKBTX_DEV_ZEROCOPY skb. It will copy all frags into kernel and drop the reference to userspace pages.

If this function is called from an interrupt gfp_mask() must be GFP_ATOMIC.

Returns 0 on success or a negative error code on failure to allocate kernel memory to copy to.

struct sk_buff * skb_clone(struct sk_buff * skb, gfp_t gfp_mask)

duplicate an sk_buff

Parameters

struct sk_buff * skb
buffer to clone
gfp_t gfp_mask
allocation priority

Description

Duplicate an sk_buff. The new one is not owned by a socket. Both copies share the same packet data but not structure. The new buffer has a reference count of 1. If the allocation fails the function returns NULL otherwise the new buffer is returned.

If this function is called from an interrupt gfp_mask() must be GFP_ATOMIC.

struct sk_buff * skb_copy(const struct sk_buff * skb, gfp_t gfp_mask)

create private copy of an sk_buff

Parameters

const struct sk_buff * skb
buffer to copy
gfp_t gfp_mask
allocation priority

Description

Make a copy of both an sk_buff and its data. This is used when the caller wishes to modify the data and needs a private copy of the data to alter. Returns NULL on failure or the pointer to the buffer on success. The returned buffer has a reference count of 1.

As by-product this function converts non-linear sk_buff to linear one, so that sk_buff becomes completely private and caller is allowed to modify all the data of returned buffer. This means that this function is not recommended for use in circumstances when only header is going to be modified. Use pskb_copy() instead.

struct sk_buff * __pskb_copy_fclone(struct sk_buff * skb, int headroom, gfp_t gfp_mask, bool fclone)

create copy of an sk_buff with private head.

Parameters

struct sk_buff * skb
buffer to copy
int headroom
headroom of new skb
gfp_t gfp_mask
allocation priority
bool fclone
if true allocate the copy of the skb from the fclone cache instead of the head cache; it is recommended to set this to true for the cases where the copy will likely be cloned

Description

Make a copy of both an sk_buff and part of its data, located in header. Fragmented data remain shared. This is used when the caller wishes to modify only header of sk_buff and needs private copy of the header to alter. Returns NULL on failure or the pointer to the buffer on success. The returned buffer has a reference count of 1.
int pskb_expand_head(struct sk_buff * skb, int nhead, int ntail, gfp_t gfp_mask)

reallocate header of sk_buff

Parameters

struct sk_buff * skb
buffer to reallocate
int nhead
room to add at head
int ntail
room to add at tail
gfp_t gfp_mask
allocation priority

Description

Expands (or creates identical copy, if nhead and ntail are zero) header of skb. sk_buff itself is not changed. sk_buff MUST have reference count of 1. Returns zero in the case of success or error, if expansion failed. In the last case, sk_buff is not changed.

All the pointers pointing into skb header may change and must be reloaded after call to this function.

struct sk_buff * skb_copy_expand(const struct sk_buff * skb, int newheadroom, int newtailroom, gfp_t gfp_mask)

copy and expand sk_buff

Parameters

const struct sk_buff * skb
buffer to copy
int newheadroom
new free bytes at head
int newtailroom
new free bytes at tail
gfp_t gfp_mask
allocation priority

Description

Make a copy of both an sk_buff and its data and while doing so allocate additional space.

This is used when the caller wishes to modify the data and needs a private copy of the data to alter as well as more space for new fields. Returns NULL on failure or the pointer to the buffer on success. The returned buffer has a reference count of 1.

You must pass GFP_ATOMIC as the allocation priority if this function is called from an interrupt.

int __skb_pad(struct sk_buff * skb, int pad, bool free_on_error)

zero pad the tail of an skb

Parameters

struct sk_buff * skb
buffer to pad
int pad
space to pad
bool free_on_error
free buffer on error

Description

Ensure that a buffer is followed by a padding area that is zero filled. Used by network drivers which may DMA or transfer data beyond the buffer end onto the wire.

May return error in out of memory cases. The skb is freed on error if free_on_error is true.

void * pskb_put(struct sk_buff * skb, struct sk_buff * tail, int len)

add data to the tail of a potentially fragmented buffer

Parameters

struct sk_buff * skb
start of the buffer to use
struct sk_buff * tail
tail fragment of the buffer to use
int len
amount of data to add

Description

This function extends the used data area of the potentially fragmented buffer. tail must be the last fragment of skb – or skb itself. If this would exceed the total buffer size the kernel will panic. A pointer to the first byte of the extra data is returned.
void * skb_put(struct sk_buff * skb, unsigned int len)

add data to a buffer

Parameters

struct sk_buff * skb
buffer to use
unsigned int len
amount of data to add

Description

This function extends the used data area of the buffer. If this would exceed the total buffer size the kernel will panic. A pointer to the first byte of the extra data is returned.
void * skb_push(struct sk_buff * skb, unsigned int len)

add data to the start of a buffer

Parameters

struct sk_buff * skb
buffer to use
unsigned int len
amount of data to add

Description

This function extends the used data area of the buffer at the buffer start. If this would exceed the total buffer headroom the kernel will panic. A pointer to the first byte of the extra data is returned.
void * skb_pull(struct sk_buff * skb, unsigned int len)

remove data from the start of a buffer

Parameters

struct sk_buff * skb
buffer to use
unsigned int len
amount of data to remove

Description

This function removes data from the start of a buffer, returning the memory to the headroom. A pointer to the next data in the buffer is returned. Once the data has been pulled future pushes will overwrite the old data.
void skb_trim(struct sk_buff * skb, unsigned int len)

remove end from a buffer

Parameters

struct sk_buff * skb
buffer to alter
unsigned int len
new length

Description

Cut the length of a buffer down by removing data from the tail. If the buffer is already under the length specified it is not modified. The skb must be linear.
void * __pskb_pull_tail(struct sk_buff * skb, int delta)

advance tail of skb header

Parameters

struct sk_buff * skb
buffer to reallocate
int delta
number of bytes to advance tail

Description

The function makes a sense only on a fragmented sk_buff, it expands header moving its tail forward and copying necessary data from fragmented part.

sk_buff MUST have reference count of 1.

Returns NULL (and sk_buff does not change) if pull failed or value of new tail of skb in the case of success.

All the pointers pointing into skb header may change and must be reloaded after call to this function.

int skb_copy_bits(const struct sk_buff * skb, int offset, void * to, int len)

copy bits from skb to kernel buffer

Parameters

const struct sk_buff * skb
source skb
int offset
offset in source
void * to
destination buffer
int len
number of bytes to copy

Description

Copy the specified number of bytes from the source skb to the destination buffer.

CAUTION ! :
If its prototype is ever changed, check arch/{*}/net/{*}.S files, since it is called from BPF assembly code.
int skb_store_bits(struct sk_buff * skb, int offset, const void * from, int len)

store bits from kernel buffer to skb

Parameters

struct sk_buff * skb
destination buffer
int offset
offset in destination
const void * from
source buffer
int len
number of bytes to copy

Description

Copy the specified number of bytes from the source buffer to the destination skb. This function handles all the messy bits of traversing fragment lists and such.
int skb_zerocopy(struct sk_buff * to, struct sk_buff * from, int len, int hlen)

Zero copy skb to skb

Parameters

struct sk_buff * to
destination buffer
struct sk_buff * from
source buffer
int len
number of bytes to copy from source buffer
int hlen
size of linear headroom in destination buffer

Description

Copies up to len bytes from from to to by creating references to the frags in the source buffer.

The hlen as calculated by skb_zerocopy_headlen() specifies the headroom in the to buffer.

Return value: 0: everything is OK -ENOMEM: couldn’t orphan frags of from due to lack of memory -EFAULT: skb_copy_bits() found some problem with skb geometry

struct sk_buff * skb_dequeue(struct sk_buff_head * list)

remove from the head of the queue

Parameters

struct sk_buff_head * list
list to dequeue from

Description

Remove the head of the list. The list lock is taken so the function may be used safely with other locking list functions. The head item is returned or NULL if the list is empty.
struct sk_buff * skb_dequeue_tail(struct sk_buff_head * list)

remove from the tail of the queue

Parameters

struct sk_buff_head * list
list to dequeue from

Description

Remove the tail of the list. The list lock is taken so the function may be used safely with other locking list functions. The tail item is returned or NULL if the list is empty.
void skb_queue_purge(struct sk_buff_head * list)

empty a list

Parameters

struct sk_buff_head * list
list to empty

Description

Delete all buffers on an sk_buff list. Each buffer is removed from the list and one reference dropped. This function takes the list lock and is atomic with respect to other list locking functions.
void skb_queue_head(struct sk_buff_head * list, struct sk_buff * newsk)

queue a buffer at the list head

Parameters

struct sk_buff_head * list
list to use
struct sk_buff * newsk
buffer to queue

Description

Queue a buffer at the start of the list. This function takes the list lock and can be used safely with other locking sk_buff functions safely.

A buffer cannot be placed on two lists at the same time.

void skb_queue_tail(struct sk_buff_head * list, struct sk_buff * newsk)

queue a buffer at the list tail

Parameters

struct sk_buff_head * list
list to use
struct sk_buff * newsk
buffer to queue

Description

Queue a buffer at the tail of the list. This function takes the list lock and can be used safely with other locking sk_buff functions safely.

A buffer cannot be placed on two lists at the same time.

remove a buffer from a list

Parameters

struct sk_buff * skb
buffer to remove
struct sk_buff_head * list
list to use

Description

Remove a packet from a list. The list locks are taken and this function is atomic with respect to other list locked calls

You must know what list the SKB is on.

void skb_append(struct sk_buff * old, struct sk_buff * newsk, struct sk_buff_head * list)

append a buffer

Parameters

struct sk_buff * old
buffer to insert after
struct sk_buff * newsk
buffer to insert
struct sk_buff_head * list
list to use

Description

Place a packet after a given packet in a list. The list locks are taken and this function is atomic with respect to other list locked calls. A buffer cannot be placed on two lists at the same time.
void skb_insert(struct sk_buff * old, struct sk_buff * newsk, struct sk_buff_head * list)

insert a buffer

Parameters

struct sk_buff * old
buffer to insert before
struct sk_buff * newsk
buffer to insert
struct sk_buff_head * list
list to use

Description

Place a packet before a given packet in a list. The list locks are taken and this function is atomic with respect to other list locked calls.

A buffer cannot be placed on two lists at the same time.

void skb_split(struct sk_buff * skb, struct sk_buff * skb1, const u32 len)

Split fragmented skb to two parts at length len.

Parameters

struct sk_buff * skb
the buffer to split
struct sk_buff * skb1
the buffer to receive the second part
const u32 len
new length for skb
void skb_prepare_seq_read(struct sk_buff * skb, unsigned int from, unsigned int to, struct skb_seq_state * st)

Prepare a sequential read of skb data

Parameters

struct sk_buff * skb
the buffer to read
unsigned int from
lower offset of data to be read
unsigned int to
upper offset of data to be read
struct skb_seq_state * st
state variable

Description

Initializes the specified state variable. Must be called before invoking skb_seq_read() for the first time.

unsigned int skb_seq_read(unsigned int consumed, const u8 ** data, struct skb_seq_state * st)

Sequentially read skb data

Parameters

unsigned int consumed
number of bytes consumed by the caller so far
const u8 ** data
destination pointer for data to be returned
struct skb_seq_state * st
state variable

Description

Reads a block of skb data at consumed relative to the lower offset specified to skb_prepare_seq_read(). Assigns the head of the data block to data and returns the length of the block or 0 if the end of the skb data or the upper offset has been reached.

The caller is not required to consume all of the data returned, i.e. consumed is typically set to the number of bytes already consumed and the next call to skb_seq_read() will return the remaining part of the block.

Note 1: The size of each block of data returned can be arbitrary,
this limitation is the cost for zerocopy sequential reads of potentially non linear data.
Note 2: Fragment lists within fragments are not implemented
at the moment, state->root_skb could be replaced with a stack for this purpose.
void skb_abort_seq_read(struct skb_seq_state * st)

Abort a sequential read of skb data

Parameters

struct skb_seq_state * st
state variable

Description

Must be called if skb_seq_read() was not called until it returned 0.

unsigned int skb_find_text(struct sk_buff * skb, unsigned int from, unsigned int to, struct ts_config * config)

Find a text pattern in skb data

Parameters

struct sk_buff * skb
the buffer to look in
unsigned int from
search offset
unsigned int to
search limit
struct ts_config * config
textsearch configuration

Description

Finds a pattern in the skb data according to the specified textsearch configuration. Use textsearch_next() to retrieve subsequent occurrences of the pattern. Returns the offset to the first occurrence or UINT_MAX if no match was found.

void * skb_pull_rcsum(struct sk_buff * skb, unsigned int len)

pull skb and update receive checksum

Parameters

struct sk_buff * skb
buffer to update
unsigned int len
length of data pulled

Description

This function performs an skb_pull on the packet and updates the CHECKSUM_COMPLETE checksum. It should be used on receive path processing instead of skb_pull unless you know that the checksum difference is zero (e.g., a valid IP header) or you are setting ip_summed to CHECKSUM_NONE.
struct sk_buff * skb_segment(struct sk_buff * head_skb, netdev_features_t features)

Perform protocol segmentation on skb.

Parameters

struct sk_buff * head_skb
buffer to segment
netdev_features_t features
features for the output path (see dev->features)

Description

This function performs segmentation on the given skb. It returns a pointer to the first in a list of new skbs for the segments. In case of error it returns ERR_PTR(err).
int skb_to_sgvec(struct sk_buff * skb, struct scatterlist * sg, int offset, int len)

Fill a scatter-gather list from a socket buffer

Parameters

struct sk_buff * skb
Socket buffer containing the buffers to be mapped
struct scatterlist * sg
The scatter-gather list to map into
int offset
The offset into the buffer’s contents to start mapping
int len
Length of buffer space to be mapped

Description

Fill the specified scatter-gather list with mappings/pointers into a region of the buffer space attached to a socket buffer. Returns either the number of scatterlist items used, or -EMSGSIZE if the contents could not fit.
int skb_cow_data(struct sk_buff * skb, int tailbits, struct sk_buff ** trailer)

Check that a socket buffer’s data buffers are writable

Parameters

struct sk_buff * skb
The socket buffer to check.
int tailbits
Amount of trailing space to be added
struct sk_buff ** trailer
Returned pointer to the skb where the tailbits space begins

Description

Make sure that the data buffers attached to a socket buffer are writable. If they are not, private copies are made of the data buffers and the socket buffer is set to use these instead.

If tailbits is given, make sure that there is space to write tailbits bytes of data beyond current end of socket buffer. trailer will be set to point to the skb in which this space begins.

The number of scatterlist elements required to completely map the COW’d and extended socket buffer will be returned.

struct sk_buff * skb_clone_sk(struct sk_buff * skb)

create clone of skb, and take reference to socket

Parameters

struct sk_buff * skb
the skb to clone

Description

This function creates a clone of a buffer that holds a reference on sk_refcnt. Buffers created via this function are meant to be returned using sock_queue_err_skb, or free via kfree_skb.

When passing buffers allocated with this function to sock_queue_err_skb it is necessary to wrap the call with sock_hold/sock_put in order to prevent the socket from being released prior to being enqueued on the sk_error_queue.

bool skb_partial_csum_set(struct sk_buff * skb, u16 start, u16 off)

set up and verify partial csum values for packet

Parameters

struct sk_buff * skb
the skb to set
u16 start
the number of bytes after skb->data to start checksumming.
u16 off
the offset from start to place the checksum.

Description

For untrusted partially-checksummed packets, we need to make sure the values for skb->csum_start and skb->csum_offset are valid so we don’t oops.

This function checks and sets those values and skb->ip_summed: if this returns false you should drop the packet.

int skb_checksum_setup(struct sk_buff * skb, bool recalculate)

set up partial checksum offset

Parameters

struct sk_buff * skb
the skb to set up
bool recalculate
if true the pseudo-header checksum will be recalculated
struct sk_buff * skb_checksum_trimmed(struct sk_buff * skb, unsigned int transport_len, __sum16(*skb_chkf) (struct sk_buff *skb)

validate checksum of an skb

Parameters

struct sk_buff * skb
the skb to check
unsigned int transport_len
the data length beyond the network header
__sum16(*)(struct sk_buff *skb) skb_chkf
checksum function to use

Description

Applies the given checksum function skb_chkf to the provided skb. Returns a checked and maybe trimmed skb. Returns NULL on error.

If the skb has data beyond the given transport length, then a trimmed & cloned skb is checked and returned.

Caller needs to set the skb transport header and free any returned skb if it differs from the provided skb.

bool skb_try_coalesce(struct sk_buff * to, struct sk_buff * from, bool * fragstolen, int * delta_truesize)

try to merge skb to prior one

Parameters

struct sk_buff * to
prior buffer
struct sk_buff * from
buffer to add
bool * fragstolen
pointer to boolean
int * delta_truesize
how much more was allocated than was requested
void skb_scrub_packet(struct sk_buff * skb, bool xnet)

scrub an skb

Parameters

struct sk_buff * skb
buffer to clean
bool xnet
packet is crossing netns

Description

skb_scrub_packet can be used after encapsulating or decapsulting a packet into/from a tunnel. Some information have to be cleared during these operations. skb_scrub_packet can also be used to clean a skb before injecting it in another namespace (xnet == true). We have to clear all information in the skb that could impact namespace isolation.

bool skb_gso_validate_network_len(const struct sk_buff * skb, unsigned int mtu)

Will a split GSO skb fit into a given MTU?

Parameters

const struct sk_buff * skb
GSO skb
unsigned int mtu
MTU to validate against

Description

skb_gso_validate_network_len validates if a given skb will fit a wanted MTU once split. It considers L3 headers, L4 headers, and the payload.

bool skb_gso_validate_mac_len(const struct sk_buff * skb, unsigned int len)

Will a split GSO skb fit in a given length?

Parameters

const struct sk_buff * skb
GSO skb
unsigned int len
length to validate against

Description

skb_gso_validate_mac_len validates if a given skb will fit a wanted length once split, including L2, L3 and L4 headers and the payload.

struct sk_buff * alloc_skb_with_frags(unsigned long header_len, unsigned long data_len, int max_page_order, int * errcode, gfp_t gfp_mask)

allocate skb with page frags

Parameters

unsigned long header_len
size of linear part
unsigned long data_len
needed length in frags
int max_page_order
max page order desired.
int * errcode
pointer to error code if any
gfp_t gfp_mask
allocation mask

Description

This can be used to allocate a paged skb, given a maximal order for frags.

bool sk_ns_capable(const struct sock * sk, struct user_namespace * user_ns, int cap)

General socket capability test

Parameters

const struct sock * sk
Socket to use a capability on or through
struct user_namespace * user_ns
The user namespace of the capability to use
int cap
The capability to use

Description

Test to see if the opener of the socket had when the socket was created and the current process has the capability cap in the user namespace user_ns.

bool sk_capable(const struct sock * sk, int cap)

Socket global capability test

Parameters

const struct sock * sk
Socket to use a capability on or through
int cap
The global capability to use

Description

Test to see if the opener of the socket had when the socket was created and the current process has the capability cap in all user namespaces.

bool sk_net_capable(const struct sock * sk, int cap)

Network namespace socket capability test

Parameters

const struct sock * sk
Socket to use a capability on or through
int cap
The capability to use

Description

Test to see if the opener of the socket had when the socket was created and the current process has the capability cap over the network namespace the socket is a member of.

void sk_set_memalloc(struct sock * sk)

sets SOCK_MEMALLOC

Parameters

struct sock * sk
socket to set it on

Description

Set SOCK_MEMALLOC on a socket for access to emergency reserves. It’s the responsibility of the admin to adjust min_free_kbytes to meet the requirements

struct sock * sk_alloc(struct net * net, int family, gfp_t priority, struct proto * prot, int kern)

All socket objects are allocated here

Parameters

struct net * net
the applicable net namespace
int family
protocol family
gfp_t priority
for allocation (GFP_KERNEL, GFP_ATOMIC, etc)
struct proto * prot
struct proto associated with this new sock instance
int kern
is this to be a kernel socket?
struct sock * sk_clone_lock(const struct sock * sk, const gfp_t priority)

clone a socket, and lock its clone

Parameters

const struct sock * sk
the socket to clone
const gfp_t priority
for allocation (GFP_KERNEL, GFP_ATOMIC, etc)

Description

Caller must unlock socket even in error path (bh_unlock_sock(newsk))
bool skb_page_frag_refill(unsigned int sz, struct page_frag * pfrag, gfp_t gfp)

check that a page_frag contains enough room

Parameters

unsigned int sz
minimum size of the fragment we want to get
struct page_frag * pfrag
pointer to page_frag
gfp_t gfp
priority for memory allocation

Note

While this allocator tries to use high order pages, there is no guarantee that allocations succeed. Therefore, sz MUST be less or equal than PAGE_SIZE.

int sk_wait_data(struct sock * sk, long * timeo, const struct sk_buff * skb)

wait for data to arrive at sk_receive_queue

Parameters

struct sock * sk
sock to wait on
long * timeo
for how long
const struct sk_buff * skb
last skb seen on sk_receive_queue

Description

Now socket state including sk->sk_err is changed only under lock, hence we may omit checks after joining wait queue. We check receive queue before schedule() only as optimization; it is very likely that release_sock() added new data.

int __sk_mem_raise_allocated(struct sock * sk, int size, int amt, int kind)

increase memory_allocated

Parameters

struct sock * sk
socket
int size
memory size to allocate
int amt
pages to allocate
int kind
allocation type

Description

Similar to __sk_mem_schedule(), but does not update sk_forward_alloc
int __sk_mem_schedule(struct sock * sk, int size, int kind)

increase sk_forward_alloc and memory_allocated

Parameters

struct sock * sk
socket
int size
memory size to allocate
int kind
allocation type

Description

If kind is SK_MEM_SEND, it means wmem allocation. Otherwise it means rmem allocation. This function assumes that protocols which have memory_pressure use sk_wmem_queued as write buffer accounting.
void __sk_mem_reduce_allocated(struct sock * sk, int amount)

reclaim memory_allocated

Parameters

struct sock * sk
socket
int amount
number of quanta

Description

Similar to __sk_mem_reclaim(), but does not update sk_forward_alloc
void __sk_mem_reclaim(struct sock * sk, int amount)

reclaim sk_forward_alloc and memory_allocated

Parameters

struct sock * sk
socket
int amount
number of bytes (rounded down to a SK_MEM_QUANTUM multiple)
bool lock_sock_fast(struct sock * sk)

fast version of lock_sock

Parameters

struct sock * sk
socket

Description

This version should be used for very small section, where process wont block return false if fast path is taken:

sk_lock.slock locked, owned = 0, BH disabled

return true if slow path is taken:

sk_lock.slock unlocked, owned = 1, BH enabled
struct sk_buff * __skb_try_recv_datagram(struct sock * sk, unsigned int flags, void (*destructor) (struct sock *sk, struct sk_buff *skb, int * peeked, int * off, int * err, struct sk_buff ** last)

Receive a datagram skbuff

Parameters

struct sock * sk
socket
unsigned int flags
MSG_ flags
void (*)(struct sock *sk, struct sk_buff *skb) destructor
invoked under the receive lock on successful dequeue
int * peeked
returns non-zero if this packet has been seen before
int * off
an offset in bytes to peek skb from. Returns an offset within an skb where data actually starts
int * err
error code returned
struct sk_buff ** last
set to last peeked message to inform the wait function what to look for when peeking

Description

Get a datagram skbuff, understands the peeking, nonblocking wakeups and possible races. This replaces identical code in packet, raw and udp, as well as the IPX AX.25 and Appletalk. It also finally fixes the long standing peek and read race for datagram sockets. If you alter this routine remember it must be re-entrant.

This function will lock the socket if a skb is returned, so the caller needs to unlock the socket in that case (usually by calling skb_free_datagram). Returns NULL with err set to -EAGAIN if no data was available or to some other value if an error was detected.

  • It does not lock socket since today. This function is
  • free of race conditions. This measure should/can improve
  • significantly datagram socket latencies at high loads,
  • when data copying to user space takes lots of time.
  • (BTW I’ve just killed the last cli() in IP/IPv6/core/netlink/packet
    1. Great win.)
  • –ANK (980729)

The order of the tests when we find no data waiting are specified quite explicitly by POSIX 1003.1g, don’t change them without having the standard around please.

int skb_kill_datagram(struct sock * sk, struct sk_buff * skb, unsigned int flags)

Free a datagram skbuff forcibly

Parameters

struct sock * sk
socket
struct sk_buff * skb
datagram skbuff
unsigned int flags
MSG_ flags

Description

This function frees a datagram skbuff that was received by skb_recv_datagram. The flags argument must match the one used for skb_recv_datagram.

If the MSG_PEEK flag is set, and the packet is still on the receive queue of the socket, it will be taken off the queue before it is freed.

This function currently only disables BH when acquiring the sk_receive_queue lock. Therefore it must not be used in a context where that lock is acquired in an IRQ context.

It returns 0 if the packet was removed by us.

int skb_copy_datagram_iter(const struct sk_buff * skb, int offset, struct iov_iter * to, int len)

Copy a datagram to an iovec iterator.

Parameters

const struct sk_buff * skb
buffer to copy
int offset
offset in the buffer to start copying from
struct iov_iter * to
iovec iterator to copy to
int len
amount of data to copy from buffer to iovec
int skb_copy_datagram_from_iter(struct sk_buff * skb, int offset, struct iov_iter * from, int len)

Copy a datagram from an iov_iter.

Parameters

struct sk_buff * skb
buffer to copy
int offset
offset in the buffer to start copying to
struct iov_iter * from
the copy source
int len
amount of data to copy to buffer from iovec

Description

Returns 0 or -EFAULT.
int zerocopy_sg_from_iter(struct sk_buff * skb, struct iov_iter * from)

Build a zerocopy datagram from an iov_iter

Parameters

struct sk_buff * skb
buffer to copy
struct iov_iter * from
the source to copy from

Description

The function will first copy up to headlen, and then pin the userspace pages and build frags through them.

Returns 0, -EFAULT or -EMSGSIZE.

int skb_copy_and_csum_datagram_msg(struct sk_buff * skb, int hlen, struct msghdr * msg)

Copy and checksum skb to user iovec.

Parameters

struct sk_buff * skb
skbuff
int hlen
hardware length
struct msghdr * msg
destination

Description

Caller _must_ check that skb will fit to this iovec.

Return

0 - success.
-EINVAL - checksum failure. -EFAULT - fault during copy.
__poll_t datagram_poll(struct file * file, struct socket * sock, poll_table * wait)

generic datagram poll

Parameters

struct file * file
file struct
struct socket * sock
socket
poll_table * wait
poll table

Description

Datagram poll: Again totally generic. This also handles sequenced packet sockets providing the socket receive queue is only ever holding data ready to receive.

Note

when you don’t use this routine for this protocol,
and you use a different write policy from sock_writeable() then please supply your own write_space callback.
int sk_stream_wait_connect(struct sock * sk, long * timeo_p)

Wait for a socket to get into the connected state

Parameters

struct sock * sk
sock to wait on
long * timeo_p
for how long to wait

Description

Must be called with the socket locked.

int sk_stream_wait_memory(struct sock * sk, long * timeo_p)

Wait for more memory for a socket

Parameters

struct sock * sk
socket to wait for memory
long * timeo_p
for how long

Socket Filter

int sk_filter_trim_cap(struct sock * sk, struct sk_buff * skb, unsigned int cap)

run a packet through a socket filter

Parameters

struct sock * sk
sock associated with sk_buff
struct sk_buff * skb
buffer to filter
unsigned int cap
limit on how short the eBPF program may trim the packet

Description

Run the eBPF program and then cut skb->data to correct size returned by the program. If pkt_len is 0 we toss packet. If skb->len is smaller than pkt_len we keep whole skb->data. This is the socket level wrapper to BPF_PROG_RUN. It returns 0 if the packet should be accepted or -EPERM if the packet should be tossed.

int bpf_prog_create(struct bpf_prog ** pfp, struct sock_fprog_kern * fprog)

create an unattached filter

Parameters

struct bpf_prog ** pfp
the unattached filter that is created
struct sock_fprog_kern * fprog
the filter program

Description

Create a filter independent of any socket. We first run some sanity checks on it to make sure it does not explode on us later. If an error occurs or there is insufficient memory for the filter a negative errno code is returned. On success the return is zero.

int bpf_prog_create_from_user(struct bpf_prog ** pfp, struct sock_fprog * fprog, bpf_aux_classic_check_t trans, bool save_orig)

create an unattached filter from user buffer

Parameters

struct bpf_prog ** pfp
the unattached filter that is created
struct sock_fprog * fprog
the filter program
bpf_aux_classic_check_t trans
post-classic verifier transformation handler
bool save_orig
save classic BPF program

Description

This function effectively does the same as bpf_prog_create(), only that it builds up its insns buffer from user space provided buffer. It also allows for passing a bpf_aux_classic_check_t handler.

int sk_attach_filter(struct sock_fprog * fprog, struct sock * sk)

attach a socket filter

Parameters

struct sock_fprog * fprog
the filter program
struct sock * sk
the socket to use

Description

Attach the user’s filter code. We first run some sanity checks on it to make sure it does not explode on us later. If an error occurs or there is insufficient memory for the filter a negative errno code is returned. On success the return is zero.

Generic Network Statistics

struct gnet_stats_basic

byte/packet throughput statistics

Definition

struct gnet_stats_basic {
  __u64 bytes;
  __u32 packets;
};

Members

bytes
number of seen bytes
packets
number of seen packets
struct gnet_stats_rate_est

rate estimator

Definition

struct gnet_stats_rate_est {
  __u32 bps;
  __u32 pps;
};

Members

bps
current byte rate
pps
current packet rate
struct gnet_stats_rate_est64

rate estimator

Definition

struct gnet_stats_rate_est64 {
  __u64 bps;
  __u64 pps;
};

Members

bps
current byte rate
pps
current packet rate
struct gnet_stats_queue

queuing statistics

Definition

struct gnet_stats_queue {
  __u32 qlen;
  __u32 backlog;
  __u32 drops;
  __u32 requeues;
  __u32 overlimits;
};

Members

qlen
queue length
backlog
backlog size of queue
drops
number of dropped packets
requeues
number of requeues
overlimits
number of enqueues over the limit
struct gnet_estimator

rate estimator configuration

Definition

struct gnet_estimator {
  signed char     interval;
  unsigned char   ewma_log;
};

Members

interval
sampling period
ewma_log
the log of measurement window weight
int gnet_stats_start_copy_compat(struct sk_buff * skb, int type, int tc_stats_type, int xstats_type, spinlock_t * lock, struct gnet_dump * d, int padattr)

start dumping procedure in compatibility mode

Parameters

struct sk_buff * skb
socket buffer to put statistics TLVs into
int type
TLV type for top level statistic TLV
int tc_stats_type
TLV type for backward compatibility struct tc_stats TLV
int xstats_type
TLV type for backward compatibility xstats TLV
spinlock_t * lock
statistics lock
struct gnet_dump * d
dumping handle
int padattr
padding attribute

Description

Initializes the dumping handle, grabs the statistic lock and appends an empty TLV header to the socket buffer for use a container for all other statistic TLVS.

The dumping handle is marked to be in backward compatibility mode telling all gnet_stats_copy_XXX() functions to fill a local copy of struct tc_stats.

Returns 0 on success or -1 if the room in the socket buffer was not sufficient.

int gnet_stats_start_copy(struct sk_buff * skb, int type, spinlock_t * lock, struct gnet_dump * d, int padattr)

start dumping procedure in compatibility mode

Parameters

struct sk_buff * skb
socket buffer to put statistics TLVs into
int type
TLV type for top level statistic TLV
spinlock_t * lock
statistics lock
struct gnet_dump * d
dumping handle
int padattr
padding attribute

Description

Initializes the dumping handle, grabs the statistic lock and appends an empty TLV header to the socket buffer for use a container for all other statistic TLVS.

Returns 0 on success or -1 if the room in the socket buffer was not sufficient.

int gnet_stats_copy_basic(const seqcount_t * running, struct gnet_dump * d, struct gnet_stats_basic_cpu __percpu * cpu, struct gnet_stats_basic_packed * b)

copy basic statistics into statistic TLV

Parameters

const seqcount_t * running
seqcount_t pointer
struct gnet_dump * d
dumping handle
struct gnet_stats_basic_cpu __percpu * cpu
copy statistic per cpu
struct gnet_stats_basic_packed * b
basic statistics

Description

Appends the basic statistics to the top level TLV created by gnet_stats_start_copy().

Returns 0 on success or -1 with the statistic lock released if the room in the socket buffer was not sufficient.

int gnet_stats_copy_basic_hw(const seqcount_t * running, struct gnet_dump * d, struct gnet_stats_basic_cpu __percpu * cpu, struct gnet_stats_basic_packed * b)

copy basic hw statistics into statistic TLV

Parameters

const seqcount_t * running
seqcount_t pointer
struct gnet_dump * d
dumping handle
struct gnet_stats_basic_cpu __percpu * cpu
copy statistic per cpu
struct gnet_stats_basic_packed * b
basic statistics

Description

Appends the basic statistics to the top level TLV created by gnet_stats_start_copy().

Returns 0 on success or -1 with the statistic lock released if the room in the socket buffer was not sufficient.

int gnet_stats_copy_rate_est(struct gnet_dump * d, struct net_rate_estimator __rcu ** rate_est)

copy rate estimator statistics into statistics TLV

Parameters

struct gnet_dump * d
dumping handle
struct net_rate_estimator __rcu ** rate_est
rate estimator

Description

Appends the rate estimator statistics to the top level TLV created by gnet_stats_start_copy().

Returns 0 on success or -1 with the statistic lock released if the room in the socket buffer was not sufficient.

int gnet_stats_copy_queue(struct gnet_dump * d, struct gnet_stats_queue __percpu * cpu_q, struct gnet_stats_queue * q, __u32 qlen)

copy queue statistics into statistics TLV

Parameters

struct gnet_dump * d
dumping handle
struct gnet_stats_queue __percpu * cpu_q
per cpu queue statistics
struct gnet_stats_queue * q
queue statistics
__u32 qlen
queue length statistics

Description

Appends the queue statistics to the top level TLV created by gnet_stats_start_copy(). Using per cpu queue statistics if they are available.

Returns 0 on success or -1 with the statistic lock released if the room in the socket buffer was not sufficient.

int gnet_stats_copy_app(struct gnet_dump * d, void * st, int len)

copy application specific statistics into statistics TLV

Parameters

struct gnet_dump * d
dumping handle
void * st
application specific statistics data
int len
length of data

Description

Appends the application specific statistics to the top level TLV created by gnet_stats_start_copy() and remembers the data for XSTATS if the dumping handle is in backward compatibility mode.

Returns 0 on success or -1 with the statistic lock released if the room in the socket buffer was not sufficient.

int gnet_stats_finish_copy(struct gnet_dump * d)

finish dumping procedure

Parameters

struct gnet_dump * d
dumping handle

Description

Corrects the length of the top level TLV to include all TLVs added by gnet_stats_copy_XXX() calls. Adds the backward compatibility TLVs if gnet_stats_start_copy_compat() was used and releases the statistics lock.

Returns 0 on success or -1 with the statistic lock released if the room in the socket buffer was not sufficient.

int gen_new_estimator(struct gnet_stats_basic_packed * bstats, struct gnet_stats_basic_cpu __percpu * cpu_bstats, struct net_rate_estimator __rcu ** rate_est, spinlock_t * lock, seqcount_t * running, struct nlattr * opt)

create a new rate estimator

Parameters

struct gnet_stats_basic_packed * bstats
basic statistics
struct gnet_stats_basic_cpu __percpu * cpu_bstats
bstats per cpu
struct net_rate_estimator __rcu ** rate_est
rate estimator statistics
spinlock_t * lock
lock for statistics and control path
seqcount_t * running
qdisc running seqcount
struct nlattr * opt
rate estimator configuration TLV

Description

Creates a new rate estimator with bstats as source and rate_est as destination. A new timer with the interval specified in the configuration TLV is created. Upon each interval, the latest statistics will be read from bstats and the estimated rate will be stored in rate_est with the statistics lock grabbed during this period.

Returns 0 on success or a negative error code.

void gen_kill_estimator(struct net_rate_estimator __rcu ** rate_est)

remove a rate estimator

Parameters

struct net_rate_estimator __rcu ** rate_est
rate estimator

Description

Removes the rate estimator.

int gen_replace_estimator(struct gnet_stats_basic_packed * bstats, struct gnet_stats_basic_cpu __percpu * cpu_bstats, struct net_rate_estimator __rcu ** rate_est, spinlock_t * lock, seqcount_t * running, struct nlattr * opt)

replace rate estimator configuration

Parameters

struct gnet_stats_basic_packed * bstats
basic statistics
struct gnet_stats_basic_cpu __percpu * cpu_bstats
bstats per cpu
struct net_rate_estimator __rcu ** rate_est
rate estimator statistics
spinlock_t * lock
lock for statistics and control path
seqcount_t * running
qdisc running seqcount (might be NULL)
struct nlattr * opt
rate estimator configuration TLV

Description

Replaces the configuration of a rate estimator by calling gen_kill_estimator() and gen_new_estimator().

Returns 0 on success or a negative error code.

bool gen_estimator_active(struct net_rate_estimator __rcu ** rate_est)

test if estimator is currently in use

Parameters

struct net_rate_estimator __rcu ** rate_est
rate estimator

Description

Returns true if estimator is active, and false if not.

SUN RPC subsystem

__be32 * xdr_encode_opaque_fixed(__be32 * p, const void * ptr, unsigned int nbytes)

Encode fixed length opaque data

Parameters

__be32 * p
pointer to current position in XDR buffer.
const void * ptr
pointer to data to encode (or NULL)
unsigned int nbytes
size of data.

Description

Copy the array of data of length nbytes at ptr to the XDR buffer at position p, then align to the next 32-bit boundary by padding with zero bytes (see RFC1832).

Note

if ptr is NULL, only the padding is performed.

Returns the updated current XDR buffer position

__be32 * xdr_encode_opaque(__be32 * p, const void * ptr, unsigned int nbytes)

Encode variable length opaque data

Parameters

__be32 * p
pointer to current position in XDR buffer.
const void * ptr
pointer to data to encode (or NULL)
unsigned int nbytes
size of data.

Description

Returns the updated current XDR buffer position

void xdr_terminate_string(struct xdr_buf * buf, const u32 len)

‘0’-terminate a string residing in an xdr_buf

Parameters

struct xdr_buf * buf
XDR buffer where string resides
const u32 len
length of string, in bytes
void _copy_from_pages(char * p, struct page ** pages, size_t pgbase, size_t len)

Parameters

char * p
pointer to destination
struct page ** pages
array of pages
size_t pgbase
offset of source data
size_t len
length

Description

Copies data into an arbitrary memory location from an array of pages The copy is assumed to be non-overlapping.

unsigned int xdr_stream_pos(const struct xdr_stream * xdr)

Return the current offset from the start of the xdr_stream

Parameters

const struct xdr_stream * xdr
pointer to struct xdr_stream
void xdr_init_encode(struct xdr_stream * xdr, struct xdr_buf * buf, __be32 * p)

Initialize a struct xdr_stream for sending data.

Parameters

struct xdr_stream * xdr
pointer to xdr_stream struct
struct xdr_buf * buf
pointer to XDR buffer in which to encode data
__be32 * p
current pointer inside XDR buffer

Note

at the moment the RPC client only passes the length of our
scratch buffer in the xdr_buf’s header kvec. Previously this meant we needed to call xdr_adjust_iovec() after encoding the data. With the new scheme, the xdr_stream manages the details of the buffer length, and takes care of adjusting the kvec length for us.
void xdr_commit_encode(struct xdr_stream * xdr)

Ensure all data is written to buffer

Parameters

struct xdr_stream * xdr
pointer to xdr_stream

Description

We handle encoding across page boundaries by giving the caller a temporary location to write to, then later copying the data into place; xdr_commit_encode does that copying.

Normally the caller doesn’t need to call this directly, as the following xdr_reserve_space will do it. But an explicit call may be required at the end of encoding, or any other time when the xdr_buf data might be read.

__be32 * xdr_reserve_space(struct xdr_stream * xdr, size_t nbytes)

Reserve buffer space for sending

Parameters

struct xdr_stream * xdr
pointer to xdr_stream
size_t nbytes
number of bytes to reserve

Description

Checks that we have enough buffer space to encode ‘nbytes’ more bytes of data. If so, update the total xdr_buf length, and adjust the length of the current kvec.

void xdr_truncate_encode(struct xdr_stream * xdr, size_t len)

truncate an encode buffer

Parameters

struct xdr_stream * xdr
pointer to xdr_stream
size_t len
new length of buffer

Description

Truncates the xdr stream, so that xdr->buf->len == len, and xdr->p points at offset len from the start of the buffer, and head, tail, and page lengths are adjusted to correspond.

If this means moving xdr->p to a different buffer, we assume that that the end pointer should be set to the end of the current page, except in the case of the head buffer when we assume the head buffer’s current length represents the end of the available buffer.

This is not safe to use on a buffer that already has inlined page cache pages (as in a zero-copy server read reply), except for the simple case of truncating from one position in the tail to another.

int xdr_restrict_buflen(struct xdr_stream * xdr, int newbuflen)

decrease available buffer space

Parameters

struct xdr_stream * xdr
pointer to xdr_stream
int newbuflen
new maximum number of bytes available

Description

Adjust our idea of how much space is available in the buffer. If we’ve already used too much space in the buffer, returns -1. If the available space is already smaller than newbuflen, returns 0 and does nothing. Otherwise, adjusts xdr->buf->buflen to newbuflen and ensures xdr->end is set at most offset newbuflen from the start of the buffer.

void xdr_write_pages(struct xdr_stream * xdr, struct page ** pages, unsigned int base, unsigned int len)

Insert a list of pages into an XDR buffer for sending

Parameters

struct xdr_stream * xdr
pointer to xdr_stream
struct page ** pages
list of pages
unsigned int base
offset of first byte
unsigned int len
length of data in bytes
void xdr_init_decode(struct xdr_stream * xdr, struct xdr_buf * buf, __be32 * p)

Initialize an xdr_stream for decoding data.

Parameters

struct xdr_stream * xdr
pointer to xdr_stream struct
struct xdr_buf * buf
pointer to XDR buffer from which to decode data
__be32 * p
current pointer inside XDR buffer
void xdr_init_decode_pages(struct xdr_stream * xdr, struct xdr_buf * buf, struct page ** pages, unsigned int len)

Initialize an xdr_stream for decoding into pages

Parameters

struct xdr_stream * xdr
pointer to xdr_stream struct
struct xdr_buf * buf
pointer to XDR buffer from which to decode data
struct page ** pages
list of pages to decode into
unsigned int len
length in bytes of buffer in pages
void xdr_set_scratch_buffer(struct xdr_stream * xdr, void * buf, size_t buflen)

Attach a scratch buffer for decoding data.

Parameters

struct xdr_stream * xdr
pointer to xdr_stream struct
void * buf
pointer to an empty buffer
size_t buflen
size of ‘buf’

Description

The scratch buffer is used when decoding from an array of pages. If an xdr_inline_decode() call spans across page boundaries, then we copy the data into the scratch buffer in order to allow linear access.

__be32 * xdr_inline_decode(struct xdr_stream * xdr, size_t nbytes)

Retrieve XDR data to decode

Parameters

struct xdr_stream * xdr
pointer to xdr_stream struct
size_t nbytes
number of bytes of data to decode

Description

Check if the input buffer is long enough to enable us to decode ‘nbytes’ more bytes of data starting at the current position. If so return the current pointer, then update the current pointer position.

unsigned int xdr_read_pages(struct xdr_stream * xdr, unsigned int len)

Ensure page-based XDR data to decode is aligned at current pointer position

Parameters

struct xdr_stream * xdr
pointer to xdr_stream struct
unsigned int len
number of bytes of page data

Description

Moves data beyond the current pointer position from the XDR head[] buffer into the page list. Any data that lies beyond current position + “len” bytes is moved into the XDR tail[].

Returns the number of XDR encoded bytes now contained in the pages

void xdr_enter_page(struct xdr_stream * xdr, unsigned int len)

decode data from the XDR page

Parameters

struct xdr_stream * xdr
pointer to xdr_stream struct
unsigned int len
number of bytes of page data

Description

Moves data beyond the current pointer position from the XDR head[] buffer into the page list. Any data that lies beyond current position + “len” bytes is moved into the XDR tail[]. The current pointer is then repositioned at the beginning of the first XDR page.

int xdr_buf_subsegment(struct xdr_buf * buf, struct xdr_buf * subbuf, unsigned int base, unsigned int len)

set subbuf to a portion of buf

Parameters

struct xdr_buf * buf
an xdr buffer
struct xdr_buf * subbuf
the result buffer
unsigned int base
beginning of range in bytes
unsigned int len
length of range in bytes

Description

sets subbuf to an xdr buffer representing the portion of buf of length len starting at offset base.

buf and subbuf may be pointers to the same struct xdr_buf.

Returns -1 if base of length are out of bounds.

void xdr_buf_trim(struct xdr_buf * buf, unsigned int len)

lop at most “len” bytes off the end of “buf”

Parameters

struct xdr_buf * buf
buf to be trimmed
unsigned int len
number of bytes to reduce “buf” by

Description

Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note that it’s possible that we’ll trim less than that amount if the xdr_buf is too small, or if (for instance) it’s all in the head and the parser has already read too far into it.

ssize_t xdr_stream_decode_opaque(struct xdr_stream * xdr, void * ptr, size_t size)

Decode variable length opaque

Parameters

struct xdr_stream * xdr
pointer to xdr_stream
void * ptr
location to store opaque data
size_t size
size of storage buffer ptr

Description

Return values:
On success, returns size of object stored in *ptr -EBADMSG on XDR buffer overflow -EMSGSIZE on overflow of storage buffer ptr
ssize_t xdr_stream_decode_opaque_dup(struct xdr_stream * xdr, void ** ptr, size_t maxlen, gfp_t gfp_flags)

Decode and duplicate variable length opaque

Parameters

struct xdr_stream * xdr
pointer to xdr_stream
void ** ptr
location to store pointer to opaque data
size_t maxlen
maximum acceptable object size
gfp_t gfp_flags
GFP mask to use

Description

Return values:
On success, returns size of object stored in *ptr -EBADMSG on XDR buffer overflow -EMSGSIZE if the size of the object would exceed maxlen -ENOMEM on memory allocation failure
ssize_t xdr_stream_decode_string(struct xdr_stream * xdr, char * str, size_t size)

Decode variable length string

Parameters

struct xdr_stream * xdr
pointer to xdr_stream
char * str
location to store string
size_t size
size of storage buffer str

Description

Return values:
On success, returns length of NUL-terminated string stored in *str -EBADMSG on XDR buffer overflow -EMSGSIZE on overflow of storage buffer str
ssize_t xdr_stream_decode_string_dup(struct xdr_stream * xdr, char ** str, size_t maxlen, gfp_t gfp_flags)

Decode and duplicate variable length string

Parameters

struct xdr_stream * xdr
pointer to xdr_stream
char ** str
location to store pointer to string
size_t maxlen
maximum acceptable string length
gfp_t gfp_flags
GFP mask to use

Description

Return values:
On success, returns length of NUL-terminated string stored in *ptr -EBADMSG on XDR buffer overflow -EMSGSIZE if the size of the string would exceed maxlen -ENOMEM on memory allocation failure
char * svc_print_addr(struct svc_rqst * rqstp, char * buf, size_t len)

Format rq_addr field for printing

Parameters

struct svc_rqst * rqstp
svc_rqst struct containing address to print
char * buf
target buffer for formatted address
size_t len
length of target buffer
void svc_reserve(struct svc_rqst * rqstp, int space)

change the space reserved for the reply to a request.

Parameters

struct svc_rqst * rqstp
The request in question
int space
new max space to reserve

Description

Each request reserves some space on the output queue of the transport to make sure the reply fits. This function reduces that reserved space to be the amount of space used already, plus space.

struct svc_xprt * svc_find_xprt(struct svc_serv * serv, const char * xcl_name, struct net * net, const sa_family_t af, const unsigned short port)

find an RPC transport instance

Parameters

struct svc_serv * serv
pointer to svc_serv to search
const char * xcl_name
C string containing transport’s class name
struct net * net
owner net pointer
const sa_family_t af
Address family of transport’s local address
const unsigned short port
transport’s IP port number

Description

Return the transport instance pointer for the endpoint accepting connections/peer traffic from the specified transport class, address family and port.

Specifying 0 for the address family or port is effectively a wild-card, and will result in matching the first transport in the service’s list that has a matching class name.

int svc_xprt_names(struct svc_serv * serv, char * buf, const int buflen)

format a buffer with a list of transport names

Parameters

struct svc_serv * serv
pointer to an RPC service
char * buf
pointer to a buffer to be filled in
const int buflen
length of buffer to be filled in

Description

Fills in buf with a string containing a list of transport names, each name terminated with ‘n’.

Returns positive length of the filled-in string on success; otherwise a negative errno value is returned if an error occurs.

int xprt_register_transport(struct xprt_class * transport)

register a transport implementation

Parameters

struct xprt_class * transport
transport to register

Description

If a transport implementation is loaded as a kernel module, it can call this interface to make itself known to the RPC client.

Return

0: transport successfully registered -EEXIST: transport already registered -EINVAL: transport module being unloaded

int xprt_unregister_transport(struct xprt_class * transport)

unregister a transport implementation

Parameters

struct xprt_class * transport
transport to unregister

Return

0: transport successfully unregistered -ENOENT: transport never registered

int xprt_load_transport(const char * transport_name)

load a transport implementation

Parameters

const char * transport_name
transport to load

Return

0: transport successfully loaded -ENOENT: transport module not available

int xprt_reserve_xprt(struct rpc_xprt * xprt, struct rpc_task * task)

serialize write access to transports

Parameters

struct rpc_xprt * xprt
pointer to the target transport
struct rpc_task * task
task that is requesting access to the transport

Description

This prevents mixing the payload of separate requests, and prevents transport connects from colliding with writes. No congestion control is provided.

void xprt_release_xprt(struct rpc_xprt * xprt, struct rpc_task * task)

allow other requests to use a transport

Parameters

struct rpc_xprt * xprt
transport with other tasks potentially waiting
struct rpc_task * task
task that is releasing access to the transport

Description

Note that “task” can be NULL. No congestion control is provided.

void xprt_release_xprt_cong(struct rpc_xprt * xprt, struct rpc_task * task)

allow other requests to use a transport

Parameters

struct rpc_xprt * xprt
transport with other tasks potentially waiting
struct rpc_task * task
task that is releasing access to the transport

Description

Note that “task” can be NULL. Another task is awoken to use the transport if the transport’s congestion window allows it.

bool xprt_request_get_cong(struct rpc_xprt * xprt, struct rpc_rqst * req)

Request congestion control credits

Parameters

struct rpc_xprt * xprt
pointer to transport
struct rpc_rqst * req
pointer to RPC request

Description

Useful for transports that require congestion control.

void xprt_release_rqst_cong(struct rpc_task * task)

housekeeping when request is complete

Parameters

struct rpc_task * task
RPC request that recently completed

Description

Useful for transports that require congestion control.

void xprt_adjust_cwnd(struct rpc_xprt * xprt, struct rpc_task * task, int result)

adjust transport congestion window

Parameters

struct rpc_xprt * xprt
pointer to xprt
struct rpc_task * task
recently completed RPC request used to adjust window
int result
result code of completed RPC request

Description

The transport code maintains an estimate on the maximum number of out- standing RPC requests, using a smoothed version of the congestion avoidance implemented in 44BSD. This is basically the Van Jacobson congestion algorithm: If a retransmit occurs, the congestion window is halved; otherwise, it is incremented by 1/cwnd when

  • a reply is received and
  • a full number of requests are outstanding and
  • the congestion window hasn’t been updated recently.
void xprt_wake_pending_tasks(struct rpc_xprt * xprt, int status)

wake all tasks on a transport’s pending queue

Parameters

struct rpc_xprt * xprt
transport with waiting tasks
int status
result code to plant in each task before waking it
void xprt_wait_for_buffer_space(struct rpc_xprt * xprt)

wait for transport output buffer to clear

Parameters

struct rpc_xprt * xprt
transport

Description

Note that we only set the timer for the case of RPC_IS_SOFT(), since we don’t in general want to force a socket disconnection due to an incomplete RPC call transmission.

bool xprt_write_space(struct rpc_xprt * xprt)

wake the task waiting for transport output buffer space

Parameters

struct rpc_xprt * xprt
transport with waiting tasks

Description

Can be called in a soft IRQ context, so xprt_write_space never sleeps.

void xprt_set_retrans_timeout_def(struct rpc_task * task)

set a request’s retransmit timeout

Parameters

struct rpc_task * task
task whose timeout is to be set

Description

Set a request’s retransmit timeout based on the transport’s default timeout parameters. Used by transports that don’t adjust the retransmit timeout based on round-trip time estimation.

void xprt_set_retrans_timeout_rtt(struct rpc_task * task)

set a request’s retransmit timeout

Parameters

struct rpc_task * task
task whose timeout is to be set

Description

Set a request’s retransmit timeout using the RTT estimator.

void xprt_disconnect_done(struct rpc_xprt * xprt)

mark a transport as disconnected

Parameters

struct rpc_xprt * xprt
transport to flag for disconnect
void xprt_force_disconnect(struct rpc_xprt * xprt)

force a transport to disconnect

Parameters

struct rpc_xprt * xprt
transport to disconnect
struct rpc_rqst * xprt_lookup_rqst(struct rpc_xprt * xprt, __be32 xid)

find an RPC request corresponding to an XID

Parameters

struct rpc_xprt * xprt
transport on which the original request was transmitted
__be32 xid
RPC XID of incoming reply

Description

Caller holds xprt->queue_lock.

void xprt_pin_rqst(struct rpc_rqst * req)

Pin a request on the transport receive list

Parameters

struct rpc_rqst * req
Request to pin

Description

Caller must ensure this is atomic with the call to xprt_lookup_rqst() so should be holding the xprt receive lock.

void xprt_unpin_rqst(struct rpc_rqst * req)

Unpin a request on the transport receive list

Parameters

struct rpc_rqst * req
Request to pin

Description

Caller should be holding the xprt receive lock.

void xprt_update_rtt(struct rpc_task * task)

Update RPC RTT statistics

Parameters

struct rpc_task * task
RPC request that recently completed

Description

Caller holds xprt->queue_lock.

void xprt_complete_rqst(struct rpc_task * task, int copied)

called when reply processing is complete

Parameters

struct rpc_task * task
RPC request that recently completed
int copied
actual number of bytes received from the transport

Description

Caller holds xprt->queue_lock.

struct rpc_xprt * xprt_get(struct rpc_xprt * xprt)

return a reference to an RPC transport.

Parameters

struct rpc_xprt * xprt
pointer to the transport
void xprt_put(struct rpc_xprt * xprt)

release a reference to an RPC transport.

Parameters

struct rpc_xprt * xprt
pointer to the transport
void rpc_wake_up(struct rpc_wait_queue * queue)

wake up all rpc_tasks

Parameters

struct rpc_wait_queue * queue
rpc_wait_queue on which the tasks are sleeping

Description

Grabs queue->lock

void rpc_wake_up_status(struct rpc_wait_queue * queue, int status)

wake up all rpc_tasks and set their status value.

Parameters

struct rpc_wait_queue * queue
rpc_wait_queue on which the tasks are sleeping
int status
status value to set

Description

Grabs queue->lock

int rpc_malloc(struct rpc_task * task)

allocate RPC buffer resources

Parameters

struct rpc_task * task
RPC task

Description

A single memory region is allocated, which is split between the RPC call and RPC reply that this task is being used for. When this RPC is retired, the memory is released by calling rpc_free.

To prevent rpciod from hanging, this allocator never sleeps, returning -ENOMEM and suppressing warning if the request cannot be serviced immediately. The caller can arrange to sleep in a way that is safe for rpciod.

Most requests are ‘small’ (under 2KiB) and can be serviced from a mempool, ensuring that NFS reads and writes can always proceed, and that there is good locality of reference for these buffers.

In order to avoid memory starvation triggering more writebacks of NFS requests, we avoid using GFP_KERNEL.

void rpc_free(struct rpc_task * task)

free RPC buffer resources allocated via rpc_malloc

Parameters

struct rpc_task * task
RPC task
int csum_partial_copy_to_xdr(struct xdr_buf * xdr, struct sk_buff * skb)

checksum and copy data

Parameters

struct xdr_buf * xdr
target XDR buffer
struct sk_buff * skb
source skb

Description

We have set things up such that we perform the checksum of the UDP packet in parallel with the copies into the RPC client iovec. -DaveM

struct rpc_iostats * rpc_alloc_iostats(struct rpc_clnt * clnt)

allocate an rpc_iostats structure

Parameters

struct rpc_clnt * clnt
RPC program, version, and xprt
void rpc_free_iostats(struct rpc_iostats * stats)

release an rpc_iostats structure

Parameters

struct rpc_iostats * stats
doomed rpc_iostats structure
void rpc_count_iostats_metrics(const struct rpc_task * task, struct rpc_iostats * op_metrics)

tally up per-task stats

Parameters

const struct rpc_task * task
completed rpc_task
struct rpc_iostats * op_metrics
stat structure for OP that will accumulate stats from task
void rpc_count_iostats(const struct rpc_task * task, struct rpc_iostats * stats)

tally up per-task stats

Parameters

const struct rpc_task * task
completed rpc_task
struct rpc_iostats * stats
array of stat structures

Description

Uses the statidx from task

int rpc_queue_upcall(struct rpc_pipe * pipe, struct rpc_pipe_msg * msg)

queue an upcall message to userspace

Parameters

struct rpc_pipe * pipe
upcall pipe on which to queue given message
struct rpc_pipe_msg * msg
message to queue

Description

Call with an inode created by rpc_mkpipe() to queue an upcall. A userspace process may then later read the upcall by performing a read on an open file for this inode. It is up to the caller to initialize the fields of msg (other than msg->list) appropriately.

struct dentry * rpc_mkpipe_dentry(struct dentry * parent, const char * name, void * private, struct rpc_pipe * pipe)

make an rpc_pipefs file for kernel<->userspace communication

Parameters

struct dentry * parent
dentry of directory to create new “pipe” in
const char * name
name of pipe
void * private
private data to associate with the pipe, for the caller’s use
struct rpc_pipe * pipe
rpc_pipe containing input parameters

Description

Data is made available for userspace to read by calls to rpc_queue_upcall(). The actual reads will result in calls to ops->upcall, which will be called with the file pointer, message, and userspace buffer to copy to.

Writes can come at any time, and do not necessarily have to be responses to upcalls. They will result in calls to msg->downcall.

The private argument passed here will be available to all these methods from the file pointer, via RPC_I(file_inode(file))->private.

remove a pipe

Parameters

struct dentry * dentry
dentry for the pipe, as returned from rpc_mkpipe

Description

After this call, lookups will no longer find the pipe, and any attempts to read or write using preexisting opens of the pipe will return -EPIPE.

void rpc_init_pipe_dir_head(struct rpc_pipe_dir_head * pdh)

initialise a struct rpc_pipe_dir_head

Parameters

struct rpc_pipe_dir_head * pdh
pointer to struct rpc_pipe_dir_head
void rpc_init_pipe_dir_object(struct rpc_pipe_dir_object * pdo, const struct rpc_pipe_dir_object_ops * pdo_ops, void * pdo_data)

initialise a struct rpc_pipe_dir_object

Parameters

struct rpc_pipe_dir_object * pdo
pointer to struct rpc_pipe_dir_object
const struct rpc_pipe_dir_object_ops * pdo_ops
pointer to const struct rpc_pipe_dir_object_ops
void * pdo_data
pointer to caller-defined data
int rpc_add_pipe_dir_object(struct net * net, struct rpc_pipe_dir_head * pdh, struct rpc_pipe_dir_object * pdo)

associate a rpc_pipe_dir_object to a directory

Parameters

struct net * net
pointer to struct net
struct rpc_pipe_dir_head * pdh
pointer to struct rpc_pipe_dir_head
struct rpc_pipe_dir_object * pdo
pointer to struct rpc_pipe_dir_object
void rpc_remove_pipe_dir_object(struct net * net, struct rpc_pipe_dir_head * pdh, struct rpc_pipe_dir_object * pdo)

remove a rpc_pipe_dir_object from a directory

Parameters

struct net * net
pointer to struct net
struct rpc_pipe_dir_head * pdh
pointer to struct rpc_pipe_dir_head
struct rpc_pipe_dir_object * pdo
pointer to struct rpc_pipe_dir_object
struct rpc_pipe_dir_object * rpc_find_or_alloc_pipe_dir_object(struct net * net, struct rpc_pipe_dir_head * pdh, int (*match) (struct rpc_pipe_dir_object *, void *, struct rpc_pipe_dir_object *(*alloc) (void *, void * data)

Parameters

struct net * net
pointer to struct net
struct rpc_pipe_dir_head * pdh
pointer to struct rpc_pipe_dir_head
int (*)(struct rpc_pipe_dir_object *, void *) match
match struct rpc_pipe_dir_object to data
struct rpc_pipe_dir_object *(*)(void *) alloc
allocate a new struct rpc_pipe_dir_object
void * data
user defined data for match() and alloc()
void rpcb_getport_async(struct rpc_task * task)

obtain the port for a given RPC service on a given host

Parameters

struct rpc_task * task
task that is waiting for portmapper request

Description

This one can be called for an ongoing RPC request, and can be used in an async (rpciod) context.

struct rpc_clnt * rpc_create(struct rpc_create_args * args)

create an RPC client and transport with one call

Parameters

struct rpc_create_args * args
rpc_clnt create argument structure

Description

Creates and initializes an RPC transport and an RPC client.

It can ping the server in order to determine if it is up, and to see if it supports this program and version. RPC_CLNT_CREATE_NOPING disables this behavior so asynchronous tasks can also use rpc_create.

struct rpc_clnt * rpc_clone_client(struct rpc_clnt * clnt)

Clone an RPC client structure

Parameters

struct rpc_clnt * clnt
RPC client whose parameters are copied

Description

Returns a fresh RPC client or an ERR_PTR.

struct rpc_clnt * rpc_clone_client_set_auth(struct rpc_clnt * clnt, rpc_authflavor_t flavor)

Clone an RPC client structure and set its auth

Parameters

struct rpc_clnt * clnt
RPC client whose parameters are copied
rpc_authflavor_t flavor
security flavor for new client

Description

Returns a fresh RPC client or an ERR_PTR.

int rpc_switch_client_transport(struct rpc_clnt * clnt, struct xprt_create * args, const struct rpc_timeout * timeout)

Parameters

struct rpc_clnt * clnt
pointer to a struct rpc_clnt
struct xprt_create * args
pointer to the new transport arguments
const struct rpc_timeout * timeout
pointer to the new timeout parameters

Description

This function allows the caller to switch the RPC transport for the rpc_clnt structure ‘clnt’ to allow it to connect to a mirrored NFS server, for instance. It assumes that the caller has ensured that there are no active RPC tasks by using some form of locking.

Returns zero if “clnt” is now using the new xprt. Otherwise a negative errno is returned, and “clnt” continues to use the old xprt.

int rpc_clnt_iterate_for_each_xprt(struct rpc_clnt * clnt, int (*fn) (struct rpc_clnt *, struct rpc_xprt *, void *, void * data)

Apply a function to all transports

Parameters

struct rpc_clnt * clnt
pointer to client
int (*)(struct rpc_clnt *, struct rpc_xprt *, void *) fn
function to apply
void * data
void pointer to function data

Description

Iterates through the list of RPC transports currently attached to the client and applies the function fn(clnt, xprt, data).

On error, the iteration stops, and the function returns the error value.

struct rpc_clnt * rpc_bind_new_program(struct rpc_clnt * old, const struct rpc_program * program, u32 vers)

bind a new RPC program to an existing client

Parameters

struct rpc_clnt * old
old rpc_client
const struct rpc_program * program
rpc program to set
u32 vers
rpc program version

Description

Clones the rpc client and sets up a new RPC program. This is mainly of use for enabling different RPC programs to share the same transport. The Sun NFSv2/v3 ACL protocol can do this.

struct rpc_task * rpc_run_task(const struct rpc_task_setup * task_setup_data)

Allocate a new RPC task, then run rpc_execute against it

Parameters

const struct rpc_task_setup * task_setup_data
pointer to task initialisation data
int rpc_call_sync(struct rpc_clnt * clnt, const struct rpc_message * msg, int flags)

Perform a synchronous RPC call

Parameters

struct rpc_clnt * clnt
pointer to RPC client
const struct rpc_message * msg
RPC call parameters
int flags
RPC call flags
int rpc_call_async(struct rpc_clnt * clnt, const struct rpc_message * msg, int flags, const struct rpc_call_ops * tk_ops, void * data)

Perform an asynchronous RPC call

Parameters

struct rpc_clnt * clnt
pointer to RPC client
const struct rpc_message * msg
RPC call parameters
int flags
RPC call flags
const struct rpc_call_ops * tk_ops
RPC call ops
void * data
user call data
size_t rpc_peeraddr(struct rpc_clnt * clnt, struct sockaddr * buf, size_t bufsize)

extract remote peer address from clnt’s xprt

Parameters

struct rpc_clnt * clnt
RPC client structure
struct sockaddr * buf
target buffer
size_t bufsize
length of target buffer

Description

Returns the number of bytes that are actually in the stored address.

const char * rpc_peeraddr2str(struct rpc_clnt * clnt, enum rpc_display_format_t format)

return remote peer address in printable format

Parameters

struct rpc_clnt * clnt
RPC client structure
enum rpc_display_format_t format
address format

Description

NB: the lifetime of the memory referenced by the returned pointer is the same as the rpc_xprt itself. As long as the caller uses this pointer, it must hold the RCU read lock.

int rpc_localaddr(struct rpc_clnt * clnt, struct sockaddr * buf, size_t buflen)

discover local endpoint address for an RPC client

Parameters

struct rpc_clnt * clnt
RPC client structure
struct sockaddr * buf
target buffer
size_t buflen
size of target buffer, in bytes

Description

Returns zero and fills in “buf” and “buflen” if successful; otherwise, a negative errno is returned.

This works even if the underlying transport is not currently connected, or if the upper layer never previously provided a source address.

The result of this function call is transient: multiple calls in succession may give different results, depending on how local networking configuration changes over time.

struct net * rpc_net_ns(struct rpc_clnt * clnt)

Get the network namespace for this RPC client

Parameters

struct rpc_clnt * clnt
RPC client to query
size_t rpc_max_payload(struct rpc_clnt * clnt)

Get maximum payload size for a transport, in bytes

Parameters

struct rpc_clnt * clnt
RPC client to query

Description

For stream transports, this is one RPC record fragment (see RFC 1831), as we don’t support multi-record requests yet. For datagram transports, this is the size of an IP packet minus the IP, UDP, and RPC header sizes.

size_t rpc_max_bc_payload(struct rpc_clnt * clnt)

Get maximum backchannel payload size, in bytes

Parameters

struct rpc_clnt * clnt
RPC client to query
void rpc_force_rebind(struct rpc_clnt * clnt)

force transport to check that remote port is unchanged

Parameters

struct rpc_clnt * clnt
client to rebind
int rpc_clnt_test_and_add_xprt(struct rpc_clnt * clnt, struct rpc_xprt_switch * xps, struct rpc_xprt * xprt, void * dummy)

Test and add a new transport to a rpc_clnt

Parameters

struct rpc_clnt * clnt
pointer to struct rpc_clnt
struct rpc_xprt_switch * xps
pointer to struct rpc_xprt_switch,
struct rpc_xprt * xprt
pointer struct rpc_xprt
void * dummy
unused
int rpc_clnt_setup_test_and_add_xprt(struct rpc_clnt * clnt, struct rpc_xprt_switch * xps, struct rpc_xprt * xprt, void * data)

Parameters

struct rpc_clnt * clnt
struct rpc_clnt to get the new transport
struct rpc_xprt_switch * xps
the rpc_xprt_switch to hold the new transport
struct rpc_xprt * xprt
the rpc_xprt to test
void * data
a struct rpc_add_xprt_test pointer that holds the test function and test function call data

Description

This is an rpc_clnt_add_xprt setup() function which returns 1 so:
1) caller of the test function must dereference the rpc_xprt_switch and the rpc_xprt. 2) test function must call rpc_xprt_switch_add_xprt, usually in the rpc_call_done routine.

Upon success (return of 1), the test function adds the new transport to the rpc_clnt xprt switch

int rpc_clnt_add_xprt(struct rpc_clnt * clnt, struct xprt_create * xprtargs, int (*setup) (struct rpc_clnt *, struct rpc_xprt_switch *, struct rpc_xprt *, void *, void * data)

Add a new transport to a rpc_clnt

Parameters

struct rpc_clnt * clnt
pointer to struct rpc_clnt
struct xprt_create * xprtargs
pointer to struct xprt_create
int (*)(struct rpc_clnt *, struct rpc_xprt_switch *, struct rpc_xprt *, void *) setup
callback to test and/or set up the connection
void * data
pointer to setup function data

Description

Creates a new transport using the parameters set in args and adds it to clnt. If ping is set, then test that connectivity succeeds before adding the new transport.

WiMAX

struct sk_buff * wimax_msg_alloc(struct wimax_dev * wimax_dev, const char * pipe_name, const void * msg, size_t size, gfp_t gfp_flags)

Create a new skb for sending a message to userspace

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor
const char * pipe_name
“named pipe” the message will be sent to
const void * msg
pointer to the message data to send
size_t size
size of the message to send (in bytes), including the header.
gfp_t gfp_flags
flags for memory allocation.

Return

0 if ok, negative errno code on error

Description

Allocates an skb that will contain the message to send to user space over the messaging pipe and initializes it, copying the payload.

Once this call is done, you can deliver it with wimax_msg_send().

IMPORTANT:

Don’t use skb_push()/skb_pull()/skb_reserve() on the skb, as wimax_msg_send() depends on skb->data being placed at the beginning of the user message.

Unlike other WiMAX stack calls, this call can be used way early, even before wimax_dev_add() is called, as long as the wimax_dev->net_dev pointer is set to point to a proper net_dev. This is so that drivers can use it early in case they need to send stuff around or communicate with user space.

const void * wimax_msg_data_len(struct sk_buff * msg, size_t * size)

Return a pointer and size of a message’s payload

Parameters

struct sk_buff * msg
Pointer to a message created with wimax_msg_alloc()
size_t * size
Pointer to where to store the message’s size

Description

Returns the pointer to the message data.

const void * wimax_msg_data(struct sk_buff * msg)

Return a pointer to a message’s payload

Parameters

struct sk_buff * msg
Pointer to a message created with wimax_msg_alloc()
ssize_t wimax_msg_len(struct sk_buff * msg)

Return a message’s payload length

Parameters

struct sk_buff * msg
Pointer to a message created with wimax_msg_alloc()
int wimax_msg_send(struct wimax_dev * wimax_dev, struct sk_buff * skb)

Send a pre-allocated message to user space

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor
struct sk_buff * skb
struct sk_buff returned by wimax_msg_alloc(). Note the ownership of skb is transferred to this function.

Return

0 if ok, < 0 errno code on error

Description

Sends a free-form message that was preallocated with wimax_msg_alloc() and filled up.

Assumes that once you pass an skb to this function for sending, it owns it and will release it when done (on success).

IMPORTANT:

Don’t use skb_push()/skb_pull()/skb_reserve() on the skb, as wimax_msg_send() depends on skb->data being placed at the beginning of the user message.

Unlike other WiMAX stack calls, this call can be used way early, even before wimax_dev_add() is called, as long as the wimax_dev->net_dev pointer is set to point to a proper net_dev. This is so that drivers can use it early in case they need to send stuff around or communicate with user space.

int wimax_msg(struct wimax_dev * wimax_dev, const char * pipe_name, const void * buf, size_t size, gfp_t gfp_flags)

Send a message to user space

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor (properly referenced)
const char * pipe_name
“named pipe” the message will be sent to
const void * buf
pointer to the message to send.
size_t size
size of the buffer pointed to by buf (in bytes).
gfp_t gfp_flags
flags for memory allocation.

Return

0 if ok, negative errno code on error.

Description

Sends a free-form message to user space on the device wimax_dev.

NOTES

Once the skb is given to this function, who will own it and will release it when done (unless it returns error).

int wimax_reset(struct wimax_dev * wimax_dev)

Reset a WiMAX device

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor

Return

0 if ok and a warm reset was done (the device still exists in the system).

-ENODEV if a cold/bus reset had to be done (device has disconnected and reconnected, so current handle is not valid any more).

-EINVAL if the device is not even registered.

Any other negative error code shall be considered as non-recoverable.

Description

Called when wanting to reset the device for any reason. Device is taken back to power on status.

This call blocks; on successful return, the device has completed the reset process and is ready to operate.

void wimax_report_rfkill_hw(struct wimax_dev * wimax_dev, enum wimax_rf_state state)

Reports changes in the hardware RF switch

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor
enum wimax_rf_state state
New state of the RF Kill switch. WIMAX_RF_ON radio on, WIMAX_RF_OFF radio off.

Description

When the device detects a change in the state of thehardware RF switch, it must call this function to let the WiMAX kernel stack know that the state has changed so it can be properly propagated.

The WiMAX stack caches the state (the driver doesn’t need to). As well, as the change is propagated it will come back as a request to change the software state to mirror the hardware state.

If the device doesn’t have a hardware kill switch, just report it on initialization as always on (WIMAX_RF_ON, radio on).

void wimax_report_rfkill_sw(struct wimax_dev * wimax_dev, enum wimax_rf_state state)

Reports changes in the software RF switch

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor
enum wimax_rf_state state
New state of the RF kill switch. WIMAX_RF_ON radio on, WIMAX_RF_OFF radio off.

Description

Reports changes in the software RF switch state to the WiMAX stack.

The main use is during initialization, so the driver can query the device for its current software radio kill switch state and feed it to the system.

On the side, the device does not change the software state by itself. In practice, this can happen, as the device might decide to switch (in software) the radio off for different reasons.

int wimax_rfkill(struct wimax_dev * wimax_dev, enum wimax_rf_state state)

Set the software RF switch state for a WiMAX device

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor
enum wimax_rf_state state
New RF state.

Return

>= 0 toggle state if ok, < 0 errno code on error. The toggle state is returned as a bitmap, bit 0 being the hardware RF state, bit 1 the software RF state.

0 means disabled (WIMAX_RF_ON, radio on), 1 means enabled radio off (WIMAX_RF_OFF).

Description

Called by the user when he wants to request the WiMAX radio to be switched on (WIMAX_RF_ON) or off (WIMAX_RF_OFF). With WIMAX_RF_QUERY, just the current state is returned.

NOTE

This call will block until the operation is complete.

void wimax_state_change(struct wimax_dev * wimax_dev, enum wimax_st new_state)

Set the current state of a WiMAX device

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor (properly referenced)
enum wimax_st new_state
New state to switch to

Description

This implements the state changes for the wimax devices. It will

  • verify that the state transition is legal (for now it’ll just print a warning if not) according to the table in linux/wimax.h’s documentation for ‘enum wimax_st’.
  • perform the actions needed for leaving the current state and whichever are needed for entering the new state.
  • issue a report to user space indicating the new state (and an optional payload with information about the new state).

NOTE

wimax_dev must be locked

enum wimax_st wimax_state_get(struct wimax_dev * wimax_dev)

Return the current state of a WiMAX device

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor

Return

Current state of the device according to its driver.

void wimax_dev_init(struct wimax_dev * wimax_dev)

initialize a newly allocated instance

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor to initialize.

Description

Initializes fields of a freshly allocated wimax_dev instance. This function assumes that after allocation, the memory occupied by wimax_dev was zeroed.

int wimax_dev_add(struct wimax_dev * wimax_dev, struct net_device * net_dev)

Register a new WiMAX device

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor (as embedded in your net_dev’s priv data). You must have called wimax_dev_init() on it before.
struct net_device * net_dev
net device the wimax_dev is associated with. The function expects SET_NETDEV_DEV() and register_netdev() were already called on it.

Description

Registers the new WiMAX device, sets up the user-kernel control interface (generic netlink) and common WiMAX infrastructure.

Note that the parts that will allow interaction with user space are setup at the very end, when the rest is in place, as once that happens, the driver might get user space control requests via netlink or from debugfs that might translate into calls into wimax_dev->op_*().

void wimax_dev_rm(struct wimax_dev * wimax_dev)

Unregister an existing WiMAX device

Parameters

struct wimax_dev * wimax_dev
WiMAX device descriptor

Description

Unregisters a WiMAX device previously registered for use with wimax_add_rm().

IMPORTANT! Must call before calling unregister_netdev().

After this function returns, you will not get any more user space control requests (via netlink or debugfs) and thus to wimax_dev->ops.

Reentrancy control is ensured by setting the state to __WIMAX_ST_QUIESCING. rfkill operations coming through wimax_*rfkill*() will be stopped by the quiescing state; ops coming from the rfkill subsystem will be stopped by the support being removed by wimax_rfkill_rm().

struct wimax_dev

Generic WiMAX device

Definition

struct wimax_dev {
  struct net_device *net_dev;
  struct list_head id_table_node;
  struct mutex mutex;
  struct mutex mutex_reset;
  enum wimax_st state;
  int (*op_msg_from_user)(struct wimax_dev *wimax_dev,const char *,const void *, size_t, const struct genl_info *info);
  int (*op_rfkill_sw_toggle)(struct wimax_dev *wimax_dev, enum wimax_rf_state);
  int (*op_reset)(struct wimax_dev *wimax_dev);
  struct rfkill *rfkill;
  unsigned int rf_hw;
  unsigned int rf_sw;
  char name[32];
  struct dentry *debugfs_dentry;
};

Members

net_dev
[fill] Pointer to the struct net_device this WiMAX device implements.
id_table_node
[private] link to the list of wimax devices kept by id-table.c. Protected by it’s own spinlock.
mutex
[private] Serializes all concurrent access and execution of operations.
mutex_reset
[private] Serializes reset operations. Needs to be a different mutex because as part of the reset operation, the driver has to call back into the stack to do things such as state change, that require wimax_dev->mutex.
state
[private] Current state of the WiMAX device.
op_msg_from_user
[fill] Driver-specific operation to handle a raw message from user space to the driver. The driver can send messages to user space using with wimax_msg_to_user().
op_rfkill_sw_toggle
[fill] Driver-specific operation to act on userspace (or any other agent) requesting the WiMAX device to change the RF Kill software switch (WIMAX_RF_ON or WIMAX_RF_OFF). If such hardware support is not present, it is assumed the radio cannot be switched off and it is always on (and the stack will error out when trying to switch it off). In such case, this function pointer can be left as NULL.
op_reset
[fill] Driver specific operation to reset the device. This operation should always attempt first a warm reset that does not disconnect the device from the bus and return 0. If that fails, it should resort to some sort of cold or bus reset (even if it implies a bus disconnection and device disappearance). In that case, -ENODEV should be returned to indicate the device is gone. This operation has to be synchronous, and return only when the reset is complete. In case of having had to resort to bus/cold reset implying a device disconnection, the call is allowed to return immediately.
rfkill
[private] integration into the RF-Kill infrastructure.
rf_hw
[private] State of the hardware radio switch (OFF/ON)
rf_sw
[private] State of the software radio switch (OFF/ON)
name
[fill] A way to identify this device. We need to register a name with many subsystems (rfkill, workqueue creation, etc). We can’t use the network device name as that might change and in some instances we don’t know it yet (until we don’t call register_netdev()). So we generate an unique one using the driver name and device bus id, place it here and use it across the board. Recommended naming: DRIVERNAME-BUSNAME:BUSID (dev->bus->name, dev->bus_id).
debugfs_dentry
[private] Used to hook up a debugfs entry. This shows up in the debugfs root as wimax:DEVICENAME.

NOTE

wimax_dev->mutex is NOT locked when this op is being
called; however, wimax_dev->mutex_reset IS locked to ensure serialization of calls to wimax_reset(). See wimax_reset()’s documentation.

Description

This structure defines a common interface to access all WiMAX devices from different vendors and provides a common API as well as a free-form device-specific messaging channel.

Usage:
  1. Embed a struct wimax_dev at the beginning the network device structure so that netdev_priv() points to it.
  2. memset() it to zero
  3. Initialize with wimax_dev_init(). This will leave the WiMAX device in the __WIMAX_ST_NULL state.
  4. Fill all the fields marked with [fill]; once called wimax_dev_add(), those fields CANNOT be modified.
  5. Call wimax_dev_add() after registering the network device. This will leave the WiMAX device in the WIMAX_ST_DOWN state. Protect the driver’s net_device->:c:func:open() against succeeding if the wimax device state is lower than WIMAX_ST_DOWN.
  6. Select when the device is going to be turned on/initialized; for example, it could be initialized on ‘ifconfig up’ (when the netdev op ‘open()’ is called on the driver).

When the device is initialized (at ifconfig up time, or right after calling wimax_dev_add() from _probe(), make sure the following steps are taken

  1. Move the device to WIMAX_ST_UNINITIALIZED. This is needed so some API calls that shouldn’t work until the device is ready can be blocked.
  2. Initialize the device. Make sure to turn the SW radio switch off and move the device to state WIMAX_ST_RADIO_OFF when done. When just initialized, a device should be left in RADIO OFF state until user space devices to turn it on.
  3. Query the device for the state of the hardware rfkill switch and call wimax_rfkill_report_hw() and wimax_rfkill_report_sw() as needed. See below.

wimax_dev_rm() undoes before unregistering the network device. Once wimax_dev_add() is called, the driver can get called on the wimax_dev->op_* function pointers

CONCURRENCY:

The stack provides a mutex for each device that will disallow API calls happening concurrently; thus, op calls into the driver through the wimax_dev->op*() function pointers will always be serialized and never concurrent.

For locking, take wimax_dev->mutex is taken; (most) operations in the API have to check for wimax_dev_is_ready() to return 0 before continuing (this is done internally).

REFERENCE COUNTING:

The WiMAX device is reference counted by the associated network device. The only operation that can be used to reference the device is wimax_dev_get_by_genl_info(), and the reference it acquires has to be released with dev_put(wimax_dev->net_dev).

RFKILL:

At startup, both HW and SW radio switchess are assumed to be off.

At initialization time [after calling wimax_dev_add()], have the driver query the device for the status of the software and hardware RF kill switches and call wimax_report_rfkill_hw() and wimax_rfkill_report_sw() to indicate their state. If any is missing, just call it to indicate it is ON (radio always on).

Whenever the driver detects a change in the state of the RF kill switches, it should call wimax_report_rfkill_hw() or wimax_report_rfkill_sw() to report it to the stack.

enum wimax_st

The different states of a WiMAX device

Constants

__WIMAX_ST_NULL
The device structure has been allocated and zeroed, but still wimax_dev_add() hasn’t been called. There is no state.
WIMAX_ST_DOWN
The device has been registered with the WiMAX and networking stacks, but it is not initialized (normally that is done with ‘ifconfig DEV up’ [or equivalent], which can upload firmware and enable communications with the device). In this state, the device is powered down and using as less power as possible. This state is the default after a call to wimax_dev_add(). It is ok to have drivers move directly to WIMAX_ST_UNINITIALIZED or WIMAX_ST_RADIO_OFF in _probe() after the call to wimax_dev_add(). It is recommended that the driver leaves this state when calling ‘ifconfig DEV up’ and enters it back on ‘ifconfig DEV down’.
__WIMAX_ST_QUIESCING
The device is being torn down, so no API operations are allowed to proceed except the ones needed to complete the device clean up process.
WIMAX_ST_UNINITIALIZED
[optional] Communication with the device is setup, but the device still requires some configuration before being operational. Some WiMAX API calls might work.
WIMAX_ST_RADIO_OFF
The device is fully up; radio is off (wether by hardware or software switches). It is recommended to always leave the device in this state after initialization.
WIMAX_ST_READY
The device is fully up and radio is on.
WIMAX_ST_SCANNING
[optional] The device has been instructed to scan. In this state, the device cannot be actively connected to a network.
WIMAX_ST_CONNECTING
The device is connecting to a network. This state exists because in some devices, the connect process can include a number of negotiations between user space, kernel space and the device. User space needs to know what the device is doing. If the connect sequence in a device is atomic and fast, the device can transition directly to CONNECTED
WIMAX_ST_CONNECTED
The device is connected to a network.
__WIMAX_ST_INVALID
This is an invalid state used to mark the maximum numeric value of states.

Description

Transitions from one state to another one are atomic and can only be caused in kernel space with wimax_state_change(). To read the state, use wimax_state_get().

States starting with __ are internal and shall not be used or referred to by drivers or userspace. They look ugly, but that’s the point – if any use is made non-internal to the stack, it is easier to catch on review.

All API operations [with well defined exceptions] will take the device mutex before starting and then check the state. If the state is __WIMAX_ST_NULL, WIMAX_ST_DOWN, WIMAX_ST_UNINITIALIZED or __WIMAX_ST_QUIESCING, it will drop the lock and quit with -EINVAL, -ENOMEDIUM, -ENOTCONN or -ESHUTDOWN.

The order of the definitions is important, so we can do numerical comparisons (eg: < WIMAX_ST_RADIO_OFF means the device is not ready to operate).

Network device support

Driver Support

void dev_add_pack(struct packet_type * pt)

add packet handler

Parameters

struct packet_type * pt
packet type declaration

Description

Add a protocol handler to the networking stack. The passed packet_type is linked into kernel lists and may not be freed until it has been removed from the kernel lists.

This call does not sleep therefore it can not guarantee all CPU’s that are in middle of receiving packets will see the new packet type (until the next received packet).

void __dev_remove_pack(struct packet_type * pt)

remove packet handler

Parameters

struct packet_type * pt
packet type declaration

Description

Remove a protocol handler that was previously added to the kernel protocol handlers by dev_add_pack(). The passed packet_type is removed from the kernel lists and can be freed or reused once this function returns.

The packet type might still be in use by receivers and must not be freed until after all the CPU’s have gone through a quiescent state.

void dev_remove_pack(struct packet_type * pt)

remove packet handler

Parameters

struct packet_type * pt
packet type declaration

Description

Remove a protocol handler that was previously added to the kernel protocol handlers by dev_add_pack(). The passed packet_type is removed from the kernel lists and can be freed or reused once this function returns.

This call sleeps to guarantee that no CPU is looking at the packet type after return.

void dev_add_offload(struct packet_offload * po)

register offload handlers

Parameters

struct packet_offload * po
protocol offload declaration

Description

Add protocol offload handlers to the networking stack. The passed proto_offload is linked into kernel lists and may not be freed until it has been removed from the kernel lists.

This call does not sleep therefore it can not guarantee all CPU’s that are in middle of receiving packets will see the new offload handlers (until the next received packet).

void dev_remove_offload(struct packet_offload * po)

remove packet offload handler

Parameters

struct packet_offload * po
packet offload declaration

Description

Remove a packet offload handler that was previously added to the kernel offload handlers by dev_add_offload(). The passed offload_type is removed from the kernel lists and can be freed or reused once this function returns.

This call sleeps to guarantee that no CPU is looking at the packet type after return.

int netdev_boot_setup_check(struct net_device * dev)

check boot time settings

Parameters

struct net_device * dev
the netdevice

Description

Check boot time settings for the device. The found settings are set for the device to be used later in the device probing. Returns 0 if no settings found, 1 if they are.

get ‘iflink’ value of a interface

Parameters

const struct net_device * dev
targeted interface

Description

Indicates the ifindex the interface is linked to. Physical interfaces have the same ‘ifindex’ and ‘iflink’ values.
int dev_fill_metadata_dst(struct net_device * dev, struct sk_buff * skb)

Retrieve tunnel egress information.

Parameters

struct net_device * dev
targeted interface
struct sk_buff * skb
The packet.

Description

For better visibility of tunnel traffic OVS needs to retrieve egress tunnel information for a packet. Following API allows user to get this info.
struct net_device * __dev_get_by_name(struct net * net, const char * name)

find a device by its name

Parameters

struct net * net
the applicable net namespace
const char * name
name to find

Description

Find an interface by name. Must be called under RTNL semaphore or dev_base_lock. If the name is found a pointer to the device is returned. If the name is not found then NULL is returned. The reference counters are not incremented so the caller must be careful with locks.
struct net_device * dev_get_by_name_rcu(struct net * net, const char * name)

find a device by its name

Parameters

struct net * net
the applicable net namespace
const char * name
name to find

Description

Find an interface by name. If the name is found a pointer to the device is returned. If the name is not found then NULL is returned. The reference counters are not incremented so the caller must be careful with locks. The caller must hold RCU lock.

struct net_device * dev_get_by_name(struct net * net, const char * name)

find a device by its name

Parameters

struct net * net
the applicable net namespace
const char * name
name to find

Description

Find an interface by name. This can be called from any context and does its own locking. The returned handle has the usage count incremented and the caller must use dev_put() to release it when it is no longer needed. NULL is returned if no matching device is found.
struct net_device * __dev_get_by_index(struct net * net, int ifindex)

find a device by its ifindex

Parameters

struct net * net
the applicable net namespace
int ifindex
index of device

Description

Search for an interface by index. Returns NULL if the device is not found or a pointer to the device. The device has not had its reference counter increased so the caller must be careful about locking. The caller must hold either the RTNL semaphore or dev_base_lock.
struct net_device * dev_get_by_index_rcu(struct net * net, int ifindex)

find a device by its ifindex

Parameters

struct net * net
the applicable net namespace
int ifindex
index of device

Description

Search for an interface by index. Returns NULL if the device is not found or a pointer to the device. The device has not had its reference counter increased so the caller must be careful about locking. The caller must hold RCU lock.
struct net_device * dev_get_by_index(struct net * net, int ifindex)

find a device by its ifindex

Parameters

struct net * net
the applicable net namespace
int ifindex
index of device

Description

Search for an interface by index. Returns NULL if the device is not found or a pointer to the device. The device returned has had a reference added and the pointer is safe until the user calls dev_put to indicate they have finished with it.
struct net_device * dev_get_by_napi_id(unsigned int napi_id)

find a device by napi_id

Parameters

unsigned int napi_id
ID of the NAPI struct

Description

Search for an interface by NAPI ID. Returns NULL if the device is not found or a pointer to the device. The device has not had its reference counter increased so the caller must be careful about locking. The caller must hold RCU lock.
struct net_device * dev_getbyhwaddr_rcu(struct net * net, unsigned short type, const char * ha)

find a device by its hardware address

Parameters

struct net * net
the applicable net namespace
unsigned short type
media type of device
const char * ha
hardware address

Description

Search for an interface by MAC address. Returns NULL if the device is not found or a pointer to the device. The caller must hold RCU or RTNL. The returned device has not had its ref count increased and the caller must therefore be careful about locking
struct net_device * __dev_get_by_flags(struct net * net, unsigned short if_flags, unsigned short mask)

find any device with given flags

Parameters

struct net * net
the applicable net namespace
unsigned short if_flags
IFF_* values
unsigned short mask
bitmask of bits in if_flags to check

Description

Search for any interface with the given flags. Returns NULL if a device is not found or a pointer to the device. Must be called inside rtnl_lock(), and result refcount is unchanged.
bool dev_valid_name(const char * name)

check if name is okay for network device

Parameters

const char * name
name string

Description

Network device names need to be valid file names to to allow sysfs to work. We also disallow any kind of whitespace.
int dev_alloc_name(struct net_device * dev, const char * name)

allocate a name for a device

Parameters

struct net_device * dev
device
const char * name
name format string

Description

Passed a format string - eg “lt``d``” it will try and find a suitable id. It scans list of devices to build up a free map, then chooses the first empty slot. The caller must hold the dev_base or rtnl lock while allocating the name and adding the device in order to avoid duplicates. Limited to bits_per_byte * page size devices (ie 32K on most platforms). Returns the number of the unit assigned or a negative errno code.
int dev_set_alias(struct net_device * dev, const char * alias, size_t len)

change ifalias of a device

Parameters

struct net_device * dev
device
const char * alias
name up to IFALIASZ
size_t len
limit of bytes to copy from info

Description

Set ifalias for a device,
void netdev_features_change(struct net_device * dev)

device changes features

Parameters

struct net_device * dev
device to cause notification

Description

Called to indicate a device has changed features.
void netdev_state_change(struct net_device * dev)

device changes state

Parameters

struct net_device * dev
device to cause notification

Description

Called to indicate a device has changed state. This function calls the notifier chains for netdev_chain and sends a NEWLINK message to the routing socket.
void netdev_notify_peers(struct net_device * dev)

notify network peers about existence of dev

Parameters

struct net_device * dev
network device

Description

Generate traffic such that interested network peers are aware of dev, such as by generating a gratuitous ARP. This may be used when a device wants to inform the rest of the network about some sort of reconfiguration such as a failover event or virtual machine migration.

int dev_open(struct net_device * dev)

prepare an interface for use.

Parameters

struct net_device * dev
device to open

Description

Takes a device from down to up state. The device’s private open function is invoked and then the multicast lists are loaded. Finally the device is moved into the up state and a NETDEV_UP message is sent to the netdev notifier chain.

Calling this function on an active interface is a nop. On a failure a negative errno code is returned.

void dev_close(struct net_device * dev)

shutdown an interface.

Parameters

struct net_device * dev
device to shutdown

Description

This function moves an active device into down state. A NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device is then deactivated and finally a NETDEV_DOWN is sent to the notifier chain.
void dev_disable_lro(struct net_device * dev)

disable Large Receive Offload on a device

Parameters

struct net_device * dev
device

Description

Disable Large Receive Offload (LRO) on a net device. Must be called under RTNL. This is needed if received packets may be forwarded to another interface.
int register_netdevice_notifier(struct notifier_block * nb)

register a network notifier block

Parameters

struct notifier_block * nb
notifier

Description

Register a notifier to be called when network device events occur. The notifier passed is linked into the kernel structures and must not be reused until it has been unregistered. A negative errno code is returned on a failure.

When registered all registration and up events are replayed to the new notifier to allow device to have a race free view of the network device list.

int unregister_netdevice_notifier(struct notifier_block * nb)

unregister a network notifier block

Parameters

struct notifier_block * nb
notifier

Description

Unregister a notifier previously registered by register_netdevice_notifier(). The notifier is unlinked into the kernel structures and may then be reused. A negative errno code is returned on a failure.

After unregistering unregister and down device events are synthesized for all devices on the device list to the removed notifier to remove the need for special case cleanup code.

int call_netdevice_notifiers(unsigned long val, struct net_device * dev)

call all network notifier blocks

Parameters

unsigned long val
value passed unmodified to notifier function
struct net_device * dev
net_device pointer passed unmodified to notifier function

Description

Call all network notifier blocks. Parameters and return value are as for raw_notifier_call_chain().
int dev_forward_skb(struct net_device * dev, struct sk_buff * skb)

loopback an skb to another netif

Parameters

struct net_device * dev
destination network device
struct sk_buff * skb
buffer to forward

Description

return values:
NET_RX_SUCCESS (no congestion) NET_RX_DROP (packet was dropped, but freed)

dev_forward_skb can be used for injecting an skb from the start_xmit function of one device into the receive queue of another device.

The receiving device may be in another namespace, so we have to clear all information in the skb that could impact namespace isolation.

bool dev_nit_active(struct net_device * dev)

return true if any network interface taps are in use

Parameters

struct net_device * dev
network device to check for the presence of taps
int netif_set_real_num_rx_queues(struct net_device * dev, unsigned int rxq)

set actual number of RX queues used

Parameters

struct net_device * dev
Network device
unsigned int rxq
Actual number of RX queues

Description

This must be called either with the rtnl_lock held or before registration of the net device. Returns 0 on success, or a negative error code. If called before registration, it always succeeds.
int netif_get_num_default_rss_queues(void)

default number of RSS queues

Parameters

void
no arguments

Description

This routine should set an upper limit on the number of RSS queues used by default by multiqueue devices.

void netif_device_detach(struct net_device * dev)

mark device as removed

Parameters

struct net_device * dev
network device

Description

Mark device as removed from system and therefore no longer available.

void netif_device_attach(struct net_device * dev)

mark device as attached

Parameters

struct net_device * dev
network device

Description

Mark device as attached from system and restart if needed.

struct sk_buff * skb_mac_gso_segment(struct sk_buff * skb, netdev_features_t features)

mac layer segmentation handler.

Parameters

struct sk_buff * skb
buffer to segment
netdev_features_t features
features for the output path (see dev->features)
struct sk_buff * __skb_gso_segment(struct sk_buff * skb, netdev_features_t features, bool tx_path)

Perform segmentation on skb.

Parameters

struct sk_buff * skb
buffer to segment
netdev_features_t features
features for the output path (see dev->features)
bool tx_path
whether it is called in TX path

Description

This function segments the given skb and returns a list of segments.

It may return NULL if the skb requires no segmentation. This is only possible when GSO is used for verifying header integrity.

Segmentation preserves SKB_SGO_CB_OFFSET bytes of previous skb cb.

int dev_loopback_xmit(struct net * net, struct sock * sk, struct sk_buff * skb)

loop back skb

Parameters

struct net * net
network namespace this loopback is happening in
struct sock * sk
sk needed to be a netfilter okfn
struct sk_buff * skb
buffer to transmit
bool rps_may_expire_flow(struct net_device * dev, u16 rxq_index, u32 flow_id, u16 filter_id)

check whether an RFS hardware filter may be removed

Parameters

struct net_device * dev
Device on which the filter was set
u16 rxq_index
RX queue index
u32 flow_id
Flow ID passed to ndo_rx_flow_steer()
u16 filter_id
Filter ID returned by ndo_rx_flow_steer()

Description

Drivers that implement ndo_rx_flow_steer() should periodically call this function for each installed filter and remove the filters for which it returns true.

int netif_rx(struct sk_buff * skb)

post buffer to the network code

Parameters

struct sk_buff * skb
buffer to post

Description

This function receives a packet from a device driver and queues it for the upper (protocol) levels to process. It always succeeds. The buffer may be dropped during processing for congestion control or by the protocol layers.

return values: NET_RX_SUCCESS (no congestion) NET_RX_DROP (packet was dropped)

bool netdev_is_rx_handler_busy(struct net_device * dev)

check if receive handler is registered

Parameters

struct net_device * dev
device to check

Description

Check if a receive handler is already registered for a given device. Return true if there one.

The caller must hold the rtnl_mutex.

int netdev_rx_handler_register(struct net_device * dev, rx_handler_func_t * rx_handler, void * rx_handler_data)

register receive handler

Parameters

struct net_device * dev
device to register a handler for
rx_handler_func_t * rx_handler
receive handler to register
void * rx_handler_data
data pointer that is used by rx handler

Description

Register a receive handler for a device. This handler will then be called from __netif_receive_skb. A negative errno code is returned on a failure.

The caller must hold the rtnl_mutex.

For a general description of rx_handler, see enum rx_handler_result.

void netdev_rx_handler_unregister(struct net_device * dev)

unregister receive handler

Parameters

struct net_device * dev
device to unregister a handler from

Description

Unregister a receive handler from a device.

The caller must hold the rtnl_mutex.

int netif_receive_skb_core(struct sk_buff * skb)

special purpose version of netif_receive_skb

Parameters

struct sk_buff * skb
buffer to process

Description

More direct receive version of netif_receive_skb(). It should only be used by callers that have a need to skip RPS and Generic XDP. Caller must also take care of handling if (page_is_)pfmemalloc.

This function may only be called from softirq context and interrupts should be enabled.

Return values (usually ignored): NET_RX_SUCCESS: no congestion NET_RX_DROP: packet was dropped

int netif_receive_skb(struct sk_buff * skb)

process receive buffer from network

Parameters

struct sk_buff * skb
buffer to process

Description

netif_receive_skb() is the main receive data processing function. It always succeeds. The buffer may be dropped during processing for congestion control or by the protocol layers.

This function may only be called from softirq context and interrupts should be enabled.

Return values (usually ignored): NET_RX_SUCCESS: no congestion NET_RX_DROP: packet was dropped

void netif_receive_skb_list(struct list_head * head)

process many receive buffers from network

Parameters

struct list_head * head
list of skbs to process.

Description

Since return value of netif_receive_skb() is normally ignored, and wouldn’t be meaningful for a list, this function returns void.

This function may only be called from softirq context and interrupts should be enabled.

void __napi_schedule(struct napi_struct * n)

schedule for receive

Parameters

struct napi_struct * n
entry to schedule

Description

The entry’s receive function will be scheduled to run. Consider using __napi_schedule_irqoff() if hard irqs are masked.

bool napi_schedule_prep(struct napi_struct * n)

check if napi can be scheduled

Parameters

struct napi_struct * n
napi context

Description

Test if NAPI routine is already running, and if not mark it as running. This is used as a condition variable insure only one NAPI poll instance runs. We also make sure there is no pending NAPI disable.

void __napi_schedule_irqoff(struct napi_struct * n)

schedule for receive

Parameters

struct napi_struct * n
entry to schedule

Description

Variant of __napi_schedule() assuming hard irqs are masked

bool netdev_has_upper_dev(struct net_device * dev, struct net_device * upper_dev)

Check if device is linked to an upper device

Parameters

struct net_device * dev
device
struct net_device * upper_dev
upper device to check

Description

Find out if a device is linked to specified upper device and return true in case it is. Note that this checks only immediate upper device, not through a complete stack of devices. The caller must hold the RTNL lock.

bool netdev_has_upper_dev_all_rcu(struct net_device * dev, struct net_device * upper_dev)

Check if device is linked to an upper device

Parameters

struct net_device * dev
device
struct net_device * upper_dev
upper device to check

Description

Find out if a device is linked to specified upper device and return true in case it is. Note that this checks the entire upper device chain. The caller must hold rcu lock.

bool netdev_has_any_upper_dev(struct net_device * dev)

Check if device is linked to some device

Parameters

struct net_device * dev
device

Description

Find out if a device is linked to an upper device and return true in case it is. The caller must hold the RTNL lock.

struct net_device * netdev_master_upper_dev_get(struct net_device * dev)

Get master upper device

Parameters

struct net_device * dev
device

Description

Find a master upper device and return pointer to it or NULL in case it’s not there. The caller must hold the RTNL lock.

struct net_device * netdev_upper_get_next_dev_rcu(struct net_device * dev, struct list_head ** iter)

Get the next dev from upper list

Parameters

struct net_device * dev
device
struct list_head ** iter
list_head ** of the current position

Description

Gets the next device from the dev’s upper list, starting from iter position. The caller must hold RCU read lock.

void * netdev_lower_get_next_private(struct net_device * dev, struct list_head ** iter)

Get the next ->private from the lower neighbour list

Parameters

struct net_device * dev
device
struct list_head ** iter
list_head ** of the current position

Description

Gets the next netdev_adjacent->private from the dev’s lower neighbour list, starting from iter position. The caller must hold either hold the RTNL lock or its own locking that guarantees that the neighbour lower list will remain unchanged.

void * netdev_lower_get_next_private_rcu(struct net_device * dev, struct list_head ** iter)

Get the next ->private from the lower neighbour list, RCU variant

Parameters

struct net_device * dev
device
struct list_head ** iter
list_head ** of the current position

Description

Gets the next netdev_adjacent->private from the dev’s lower neighbour list, starting from iter position. The caller must hold RCU read lock.

void * netdev_lower_get_next(struct net_device * dev, struct list_head ** iter)

Get the next device from the lower neighbour list

Parameters

struct net_device * dev
device
struct list_head ** iter
list_head ** of the current position

Description

Gets the next netdev_adjacent from the dev’s lower neighbour list, starting from iter position. The caller must hold RTNL lock or its own locking that guarantees that the neighbour lower list will remain unchanged.

void * netdev_lower_get_first_private_rcu(struct net_device * dev)

Get the first ->private from the lower neighbour list, RCU variant

Parameters

struct net_device * dev
device

Description

Gets the first netdev_adjacent->private from the dev’s lower neighbour list. The caller must hold RCU read lock.

struct net_device * netdev_master_upper_dev_get_rcu(struct net_device * dev)

Get master upper device

Parameters

struct net_device * dev
device

Description

Find a master upper device and return pointer to it or NULL in case it’s not there. The caller must hold the RCU read lock.

Add a link to the upper device

Parameters

struct net_device * dev
device
struct net_device * upper_dev
new upper device
struct netlink_ext_ack * extack
netlink extended ack

Description

Adds a link to device which is upper to this one. The caller must hold the RTNL lock. On a failure a negative errno code is returned. On success the reference counts are adjusted and the function returns zero.

Add a master link to the upper device

Parameters

struct net_device * dev
device
struct net_device * upper_dev
new upper device
void * upper_priv
upper device private
void * upper_info
upper info to be passed down via notifier
struct netlink_ext_ack * extack
netlink extended ack

Description

Adds a link to device which is upper to this one. In this case, only one master upper device can be linked, although other non-master devices might be linked as well. The caller must hold the RTNL lock. On a failure a negative errno code is returned. On success the reference counts are adjusted and the function returns zero.

Removes a link to upper device

Parameters

struct net_device * dev
device
struct net_device * upper_dev
new upper device

Description

Removes a link to device which is upper to this one. The caller must hold the RTNL lock.

void netdev_bonding_info_change(struct net_device * dev, struct netdev_bonding_info * bonding_info)

Dispatch event about slave change

Parameters

struct net_device * dev
device
struct netdev_bonding_info * bonding_info
info to dispatch

Description

Send NETDEV_BONDING_INFO to netdev notifiers with info. The caller must hold the RTNL lock.

void netdev_lower_state_changed(struct net_device * lower_dev, void * lower_state_info)

Dispatch event about lower device state change

Parameters

struct net_device * lower_dev
device
void * lower_state_info
state to dispatch

Description

Send NETDEV_CHANGELOWERSTATE to netdev notifiers with info. The caller must hold the RTNL lock.

int dev_set_promiscuity(struct net_device * dev, int inc)

update promiscuity count on a device

Parameters

struct net_device * dev
device
int inc
modifier

Description

Add or remove promiscuity from a device. While the count in the device remains above zero the interface remains promiscuous. Once it hits zero the device reverts back to normal filtering operation. A negative inc value is used to drop promiscuity on the device. Return 0 if successful or a negative errno code on error.
int dev_set_allmulti(struct net_device * dev, int inc)

update allmulti count on a device

Parameters

struct net_device * dev
device
int inc
modifier

Description

Add or remove reception of all multicast frames to a device. While the count in the device remains above zero the interface remains listening to all interfaces. Once it hits zero the device reverts back to normal filtering operation. A negative inc value is used to drop the counter when releasing a resource needing all multicasts. Return 0 if successful or a negative errno code on error.
unsigned int dev_get_flags(const struct net_device * dev)

get flags reported to userspace

Parameters

const struct net_device * dev
device

Description

Get the combination of flag bits exported through APIs to userspace.
int dev_change_flags(struct net_device * dev, unsigned int flags)

change device settings

Parameters

struct net_device * dev
device
unsigned int flags
device state flags

Description

Change settings on device based state flags. The flags are in the userspace exported format.
void dev_set_group(struct net_device * dev, int new_group)

Change group this device belongs to

Parameters

struct net_device * dev
device
int new_group
group this device should belong to
int dev_set_mac_address(struct net_device * dev, struct sockaddr * sa)

Change Media Access Control Address

Parameters

struct net_device * dev
device
struct sockaddr * sa
new address

Description

Change the hardware (MAC) address of the device
int dev_change_carrier(struct net_device * dev, bool new_carrier)

Change device carrier

Parameters

struct net_device * dev
device
bool new_carrier
new value

Description

Change device carrier
int dev_get_phys_port_id(struct net_device * dev, struct netdev_phys_item_id * ppid)

Get device physical port ID

Parameters

struct net_device * dev
device
struct netdev_phys_item_id * ppid
port ID

Description

Get device physical port ID
int dev_get_phys_port_name(struct net_device * dev, char * name, size_t len)

Get device physical port name

Parameters

struct net_device * dev
device
char * name
port name
size_t len
limit of bytes to copy to name

Description

Get device physical port name
int dev_change_proto_down(struct net_device * dev, bool proto_down)

update protocol port state information

Parameters

struct net_device * dev
device
bool proto_down
new value

Description

This info can be used by switch drivers to set the phys state of the port.
void netdev_update_features(struct net_device * dev)

recalculate device features

Parameters

struct net_device * dev
the device to check

Description

Recalculate dev->features set and send notifications if it has changed. Should be called after driver or hardware dependent conditions might have changed that influence the features.
void netdev_change_features(struct net_device * dev)

recalculate device features

Parameters

struct net_device * dev
the device to check

Description

Recalculate dev->features set and send notifications even if they have not changed. Should be called instead of netdev_update_features() if also dev->vlan_features might have changed to allow the changes to be propagated to stacked VLAN devices.
void netif_stacked_transfer_operstate(const struct net_device * rootdev, struct net_device * dev)

transfer operstate

Parameters

const struct net_device * rootdev
the root or lower level device to transfer state from
struct net_device * dev
the device to transfer operstate to

Description

Transfer operational state from root to device. This is normally called when a stacking relationship exists between the root device and the device(a leaf device).
int register_netdevice(struct net_device * dev)

register a network device

Parameters

struct net_device * dev
device to register

Description

Take a completed network device structure and add it to the kernel interfaces. A NETDEV_REGISTER message is sent to the netdev notifier chain. 0 is returned on success. A negative errno code is returned on a failure to set up the device, or if the name is a duplicate.

Callers must hold the rtnl semaphore. You may want register_netdev() instead of this.

BUGS: The locking appears insufficient to guarantee two parallel registers will not get the same name.

int init_dummy_netdev(struct net_device * dev)

init a dummy network device for NAPI

Parameters

struct net_device * dev
device to init

Description

This takes a network device structure and initialize the minimum amount of fields so it can be used to schedule NAPI polls without registering a full blown interface. This is to be used by drivers that need to tie several hardware interfaces to a single NAPI poll scheduler due to HW limitations.
int register_netdev(struct net_device * dev)

register a network device

Parameters

struct net_device * dev
device to register

Description

Take a completed network device structure and add it to the kernel interfaces. A NETDEV_REGISTER message is sent to the netdev notifier chain. 0 is returned on success. A negative errno code is returned on a failure to set up the device, or if the name is a duplicate.

This is a wrapper around register_netdevice that takes the rtnl semaphore and expands the device name if you passed a format string to alloc_netdev.

struct rtnl_link_stats64 * dev_get_stats(struct net_device * dev, struct rtnl_link_stats64 * storage)

get network device statistics

Parameters

struct net_device * dev
device to get statistics from
struct rtnl_link_stats64 * storage
place to store stats

Description

Get network statistics from device. Return storage. The device driver may provide its own method by setting dev->netdev_ops->get_stats64 or dev->netdev_ops->get_stats; otherwise the internal statistics structure is used.
struct net_device * alloc_netdev_mqs(int sizeof_priv, const char * name, unsigned char name_assign_type, void (*setup) (struct net_device *, unsigned int txqs, unsigned int rxqs)

allocate network device

Parameters

int sizeof_priv
size of private data to allocate space for
const char * name
device name format string
unsigned char name_assign_type
origin of device name
void (*)(struct net_device *) setup
callback to initialize device
unsigned int txqs
the number of TX subqueues to allocate
unsigned int rxqs
the number of RX subqueues to allocate

Description

Allocates a struct net_device with private data area for driver use and performs basic initialization. Also allocates subqueue structs for each queue on the device.

void free_netdev(struct net_device * dev)

free network device

Parameters

struct net_device * dev
device

Description

This function does the last stage of destroying an allocated device interface. The reference to the device object is released. If this is the last reference then it will be freed.Must be called in process context.

void synchronize_net(void)

Synchronize with packet receive processing

Parameters

void
no arguments

Description

Wait for packets currently being received to be done. Does not block later packets from starting.
void unregister_netdevice_queue(struct net_device * dev, struct list_head * head)

remove device from the kernel

Parameters

struct net_device * dev
device
struct list_head * head
list

Description

This function shuts down a device interface and removes it from the kernel tables. If head not NULL, device is queued to be unregistered later.

Callers must hold the rtnl semaphore. You may want unregister_netdev() instead of this.

void unregister_netdevice_many(struct list_head * head)

unregister many devices

Parameters

struct list_head * head
list of devices

Note

As most callers use a stack allocated list_head,
we force a list_del() to make sure stack wont be corrupted later.
void unregister_netdev(struct net_device * dev)

remove device from the kernel

Parameters

struct net_device * dev
device

Description

This function shuts down a device interface and removes it from the kernel tables.

This is just a wrapper for unregister_netdevice that takes the rtnl semaphore. In general you want to use this and not unregister_netdevice.

int dev_change_net_namespace(struct net_device * dev, struct net * net, const char * pat)

move device to different nethost namespace

Parameters

struct net_device * dev
device
struct net * net
network namespace
const char * pat
If not NULL name pattern to try if the current device name is already taken in the destination network namespace.

Description

This function shuts down a device interface and moves it to a new network namespace. On success 0 is returned, on a failure a netagive errno code is returned.

Callers must hold the rtnl semaphore.

netdev_features_t netdev_increment_features(netdev_features_t all, netdev_features_t one, netdev_features_t mask)

increment feature set by one

Parameters

netdev_features_t all
current feature set
netdev_features_t one
new feature set
netdev_features_t mask
mask feature set

Description

Computes a new feature set after adding a device with feature set one to the master device with current feature set all. Will not enable anything that is off in mask. Returns the new feature set.
int eth_header(struct sk_buff * skb, struct net_device * dev, unsigned short type, const void * daddr, const void * saddr, unsigned int len)

create the Ethernet header

Parameters

struct sk_buff * skb
buffer to alter
struct net_device * dev
source device
unsigned short type
Ethernet type field
const void * daddr
destination address (NULL leave destination address)
const void * saddr
source address (NULL use device source address)
unsigned int len
packet length (<= skb->len)

Description

Set the protocol type. For a packet of type ETH_P_802_3/2 we put the length in here instead.

u32 eth_get_headlen(void * data, unsigned int len)

determine the length of header for an ethernet frame

Parameters

void * data
pointer to start of frame
unsigned int len
total length of frame

Description

Make a best effort attempt to pull the length for all of the headers for a given frame in a linear buffer.

__be16 eth_type_trans(struct sk_buff * skb, struct net_device * dev)

determine the packet’s protocol ID.

Parameters

struct sk_buff * skb
received socket data
struct net_device * dev
receiving network device

Description

The rule here is that we assume 802.3 if the type field is short enough to be a length. This is normal practice and works for any ‘now in use’ protocol.

int eth_header_parse(const struct sk_buff * skb, unsigned char * haddr)

extract hardware address from packet

Parameters

const struct sk_buff * skb
packet to extract header from
unsigned char * haddr
destination buffer
int eth_header_cache(const struct neighbour * neigh, struct hh_cache * hh, __be16 type)

fill cache entry from neighbour

Parameters

const struct neighbour * neigh
source neighbour
struct hh_cache * hh
destination cache entry
__be16 type
Ethernet type field

Description

Create an Ethernet header template from the neighbour.

void eth_header_cache_update(struct hh_cache * hh, const struct net_device * dev, const unsigned char * haddr)

update cache entry

Parameters

struct hh_cache * hh
destination cache entry
const struct net_device * dev
network device
const unsigned char * haddr
new hardware address

Description

Called by Address Resolution module to notify changes in address.

int eth_prepare_mac_addr_change(struct net_device * dev, void * p)

prepare for mac change

Parameters

struct net_device * dev
network device
void * p
socket address
void eth_commit_mac_addr_change(struct net_device * dev, void * p)

commit mac change

Parameters

struct net_device * dev
network device
void * p
socket address
int eth_mac_addr(struct net_device * dev, void * p)

set new Ethernet hardware address

Parameters

struct net_device * dev
network device
void * p
socket address

Description

Change hardware address of device.

This doesn’t change hardware matching, so needs to be overridden for most real devices.

int eth_change_mtu(struct net_device * dev, int new_mtu)

set new MTU size

Parameters

struct net_device * dev
network device
int new_mtu
new Maximum Transfer Unit

Description

Allow changing MTU size. Needs to be overridden for devices supporting jumbo frames.

void ether_setup(struct net_device * dev)

setup Ethernet network device

Parameters

struct net_device * dev
network device

Description

Fill in the fields of the device structure with Ethernet-generic values.

struct net_device * alloc_etherdev_mqs(int sizeof_priv, unsigned int txqs, unsigned int rxqs)

Allocates and sets up an Ethernet device

Parameters

int sizeof_priv
Size of additional driver-private structure to be allocated for this Ethernet device
unsigned int txqs
The number of TX queues this device has.
unsigned int rxqs
The number of RX queues this device has.

Description

Fill in the fields of the device structure with Ethernet-generic values. Basically does everything except registering the device.

Constructs a new net device, complete with a private data area of size (sizeof_priv). A 32-byte (not bit) alignment is enforced for this private data area.

void netif_carrier_on(struct net_device * dev)

set carrier

Parameters

struct net_device * dev
network device

Description

Device has detected that carrier.

void netif_carrier_off(struct net_device * dev)

clear carrier

Parameters

struct net_device * dev
network device

Description

Device has detected loss of carrier.

Determine if given Ethernet address is link-local

Parameters

const u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Return true if address is link local reserved addr (01:80:c2:00:00:0X) per IEEE 802.1Q 8.6.3 Frame filtering.

Please note: addr must be aligned to u16.

bool is_zero_ether_addr(const u8 * addr)

Determine if give Ethernet address is all zeros.

Parameters

const u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Return true if the address is all zeroes.

Please note: addr must be aligned to u16.

bool is_multicast_ether_addr(const u8 * addr)

Determine if the Ethernet address is a multicast.

Parameters

const u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Return true if the address is a multicast address. By definition the broadcast address is also a multicast address.

bool is_local_ether_addr(const u8 * addr)

Determine if the Ethernet address is locally-assigned one (IEEE 802).

Parameters

const u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Return true if the address is a local address.

bool is_broadcast_ether_addr(const u8 * addr)

Determine if the Ethernet address is broadcast

Parameters

const u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Return true if the address is the broadcast address.

Please note: addr must be aligned to u16.

bool is_unicast_ether_addr(const u8 * addr)

Determine if the Ethernet address is unicast

Parameters

const u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Return true if the address is a unicast address.

bool is_valid_ether_addr(const u8 * addr)

Determine if the given Ethernet address is valid

Parameters

const u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Check that the Ethernet address (MAC) is not 00:00:00:00:00:00, is not a multicast address, and is not FF:FF:FF:FF:FF:FF.

Return true if the address is valid.

Please note: addr must be aligned to u16.

bool eth_proto_is_802_3(__be16 proto)

Determine if a given Ethertype/length is a protocol

Parameters

__be16 proto
Ethertype/length value to be tested

Description

Check that the value from the Ethertype/length field is a valid Ethertype.

Return true if the valid is an 802.3 supported Ethertype.

void eth_random_addr(u8 * addr)

Generate software assigned random Ethernet address

Parameters

u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Generate a random Ethernet address (MAC) that is not multicast and has the local assigned bit set.

void eth_broadcast_addr(u8 * addr)

Assign broadcast address

Parameters

u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Assign the broadcast address to the given address array.

void eth_zero_addr(u8 * addr)

Assign zero address

Parameters

u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Assign the zero address to the given address array.

void eth_hw_addr_random(struct net_device * dev)

Generate software assigned random Ethernet and set device flag

Parameters

struct net_device * dev
pointer to net_device structure

Description

Generate a random Ethernet address (MAC) to be used by a net device and set addr_assign_type so the state can be read by sysfs and be used by userspace.

void ether_addr_copy(u8 * dst, const u8 * src)

Copy an Ethernet address

Parameters

u8 * dst
Pointer to a six-byte array Ethernet address destination
const u8 * src
Pointer to a six-byte array Ethernet address source

Description

Please note: dst & src must both be aligned to u16.

void eth_hw_addr_inherit(struct net_device * dst, struct net_device * src)

Copy dev_addr from another net_device

Parameters

struct net_device * dst
pointer to net_device to copy dev_addr to
struct net_device * src
pointer to net_device to copy dev_addr from

Description

Copy the Ethernet address from one net_device to another along with the address attributes (addr_assign_type).

bool ether_addr_equal(const u8 * addr1, const u8 * addr2)

Compare two Ethernet addresses

Parameters

const u8 * addr1
Pointer to a six-byte array containing the Ethernet address
const u8 * addr2
Pointer other six-byte array containing the Ethernet address

Description

Compare two Ethernet addresses, returns true if equal

Please note: addr1 & addr2 must both be aligned to u16.

bool ether_addr_equal_64bits(const u8 addr1, const u8 addr2)

Compare two Ethernet addresses

Parameters

const u8 addr1
Pointer to an array of 8 bytes
const u8 addr2
Pointer to an other array of 8 bytes

Description

Compare two Ethernet addresses, returns true if equal, false otherwise.

The function doesn’t need any conditional branches and possibly uses word memory accesses on CPU allowing cheap unaligned memory reads. arrays = { byte1, byte2, byte3, byte4, byte5, byte6, pad1, pad2 }

Please note that alignment of addr1 & addr2 are only guaranteed to be 16 bits.

bool ether_addr_equal_unaligned(const u8 * addr1, const u8 * addr2)

Compare two not u16 aligned Ethernet addresses

Parameters

const u8 * addr1
Pointer to a six-byte array containing the Ethernet address
const u8 * addr2
Pointer other six-byte array containing the Ethernet address

Description

Compare two Ethernet addresses, returns true if equal

Please note: Use only when any Ethernet address may not be u16 aligned.

bool ether_addr_equal_masked(const u8 * addr1, const u8 * addr2, const u8 * mask)

Compare two Ethernet addresses with a mask

Parameters

const u8 * addr1
Pointer to a six-byte array containing the 1st Ethernet address
const u8 * addr2
Pointer to a six-byte array containing the 2nd Ethernet address
const u8 * mask
Pointer to a six-byte array containing the Ethernet address bitmask

Description

Compare two Ethernet addresses with a mask, returns true if for every bit set in the bitmask the equivalent bits in the ethernet addresses are equal. Using a mask with all bits set is a slower ether_addr_equal.

u64 ether_addr_to_u64(const u8 * addr)

Convert an Ethernet address into a u64 value.

Parameters

const u8 * addr
Pointer to a six-byte array containing the Ethernet address

Description

Return a u64 value of the address

void u64_to_ether_addr(u64 u, u8 * addr)

Convert a u64 to an Ethernet address.

Parameters

u64 u
u64 to convert to an Ethernet MAC address
u8 * addr
Pointer to a six-byte array to contain the Ethernet address
void eth_addr_dec(u8 * addr)

Decrement the given MAC address

Parameters

u8 * addr
Pointer to a six-byte array containing Ethernet address to decrement
bool is_etherdev_addr(const struct net_device * dev, const u8 addr)

Tell if given Ethernet address belongs to the device.

Parameters

const struct net_device * dev
Pointer to a device structure
const u8 addr
Pointer to a six-byte array containing the Ethernet address

Description

Compare passed address with all addresses of the device. Return true if the address if one of the device addresses.

Note that this function calls ether_addr_equal_64bits() so take care of the right padding.

unsigned long compare_ether_header(const void * a, const void * b)

Compare two Ethernet headers

Parameters

const void * a
Pointer to Ethernet header
const void * b
Pointer to Ethernet header

Description

Compare two Ethernet headers, returns 0 if equal. This assumes that the network header (i.e., IP header) is 4-byte aligned OR the platform can handle unaligned access. This is the case for all packets coming into netif_receive_skb or similar entry points.

int eth_skb_pad(struct sk_buff * skb)

Pad buffer to mininum number of octets for Ethernet frame

Parameters

struct sk_buff * skb
Buffer to pad

Description

An Ethernet frame should have a minimum size of 60 bytes. This function takes short frames and pads them with zeros up to the 60 byte limit.

void napi_schedule(struct napi_struct * n)

schedule NAPI poll

Parameters

struct napi_struct * n
NAPI context

Description

Schedule NAPI poll routine to be called if it is not already running.

void napi_schedule_irqoff(struct napi_struct * n)

schedule NAPI poll

Parameters

struct napi_struct * n
NAPI context

Description

Variant of napi_schedule(), assuming hard irqs are masked.

bool napi_complete(struct napi_struct * n)

NAPI processing complete

Parameters

struct napi_struct * n
NAPI context

Description

Mark NAPI processing as complete. Consider using napi_complete_done() instead. Return false if device should avoid rearming interrupts.

bool napi_hash_del(struct napi_struct * napi)

remove a NAPI from global table

Parameters

struct napi_struct * napi
NAPI context

Description

Warning: caller must observe RCU grace period before freeing memory containing napi, if this function returns true.

Note

core networking stack automatically calls it from netif_napi_del(). Drivers might want to call this helper to combine all the needed RCU grace periods into a single one.

void napi_disable(struct napi_struct * n)

prevent NAPI from scheduling

Parameters

struct napi_struct * n
NAPI context

Description

Stop NAPI from being scheduled on this context. Waits till any outstanding processing completes.

void napi_enable(struct napi_struct * n)

enable NAPI scheduling

Parameters

struct napi_struct * n
NAPI context

Description

Resume NAPI from being scheduled on this context. Must be paired with napi_disable.

void napi_synchronize(const struct napi_struct * n)

wait until NAPI is not running

Parameters

const struct napi_struct * n
NAPI context

Description

Wait until NAPI is done being scheduled on this context. Waits till any outstanding processing completes but does not disable future activations.

bool napi_if_scheduled_mark_missed(struct napi_struct * n)

if napi is running, set the NAPIF_STATE_MISSED

Parameters

struct napi_struct * n
NAPI context

Description

If napi is running, set the NAPIF_STATE_MISSED, and return true if NAPI is scheduled.

enum netdev_priv_flags

struct net_device priv_flags

Constants

IFF_802_1Q_VLAN
802.1Q VLAN device
IFF_EBRIDGE
Ethernet bridging device
IFF_BONDING
bonding master or slave
IFF_ISATAP
ISATAP interface (RFC4214)
IFF_WAN_HDLC
WAN HDLC device
IFF_XMIT_DST_RELEASE
dev_hard_start_xmit() is allowed to release skb->dst
IFF_DONT_BRIDGE
disallow bridging this ether dev
IFF_DISABLE_NETPOLL
disable netpoll at run-time
IFF_MACVLAN_PORT
device used as macvlan port
IFF_BRIDGE_PORT
device used as bridge port
IFF_OVS_DATAPATH
device used as Open vSwitch datapath port
IFF_TX_SKB_SHARING
The interface supports sharing skbs on transmit
IFF_UNICAST_FLT
Supports unicast filtering
IFF_TEAM_PORT
device used as team port
IFF_SUPP_NOFCS
device supports sending custom FCS
IFF_LIVE_ADDR_CHANGE
device supports hardware address change when it’s running
IFF_MACVLAN
Macvlan device
IFF_XMIT_DST_RELEASE_PERM
IFF_XMIT_DST_RELEASE not taking into account underlying stacked devices
IFF_L3MDEV_MASTER
device is an L3 master device
IFF_NO_QUEUE
device can run without qdisc attached
IFF_OPENVSWITCH
device is a Open vSwitch master
IFF_L3MDEV_SLAVE
device is enslaved to an L3 master device
IFF_TEAM
device is a team device
IFF_RXFH_CONFIGURED
device has had Rx Flow indirection table configured
IFF_PHONY_HEADROOM
the headroom value is controlled by an external entity (i.e. the master device for bridged veth)
IFF_MACSEC
device is a MACsec device
IFF_NO_RX_HANDLER
device doesn’t support the rx_handler hook
IFF_FAILOVER
device is a failover master device
IFF_FAILOVER_SLAVE
device is lower dev of a failover master device

Description

These are the struct net_device, they are only set internally by drivers and used in the kernel. These flags are invisible to userspace; this means that the order of these flags can change during any kernel release.

You should have a pretty good reason to be extending these flags.

struct net_device

The DEVICE structure.

Definition

struct net_device {
  char name[IFNAMSIZ];
  struct hlist_node       name_hlist;
  struct dev_ifalias      __rcu *ifalias;
  unsigned long           mem_end;
  unsigned long           mem_start;
  unsigned long           base_addr;
  int irq;
  unsigned long           state;
  struct list_head        dev_list;
  struct list_head        napi_list;
  struct list_head        unreg_list;
  struct list_head        close_list;
  struct list_head        ptype_all;
  struct list_head        ptype_specific;
  struct {
    struct list_head upper;
    struct list_head lower;
  } adj_list;
  netdev_features_t features;
  netdev_features_t hw_features;
  netdev_features_t wanted_features;
  netdev_features_t vlan_features;
  netdev_features_t hw_enc_features;
  netdev_features_t mpls_features;
  netdev_features_t gso_partial_features;
  int ifindex;
  int group;
  struct net_device_stats stats;
  atomic_long_t rx_dropped;
  atomic_long_t tx_dropped;
  atomic_long_t rx_nohandler;
  atomic_t carrier_up_count;
  atomic_t carrier_down_count;
#ifdef CONFIG_WIRELESS_EXT;
  const struct iw_handler_def *wireless_handlers;
  struct iw_public_data   *wireless_data;
#endif;
  const struct net_device_ops *netdev_ops;
  const struct ethtool_ops *ethtool_ops;
#ifdef CONFIG_NET_SWITCHDEV;
  const struct switchdev_ops *switchdev_ops;
#endif;
#ifdef CONFIG_NET_L3_MASTER_DEV;
  const struct l3mdev_ops *l3mdev_ops;
#endif;
#if IS_ENABLED(CONFIG_IPV6);
  const struct ndisc_ops *ndisc_ops;
#endif;
#ifdef CONFIG_XFRM_OFFLOAD;
  const struct xfrmdev_ops *xfrmdev_ops;
#endif;
#if IS_ENABLED(CONFIG_TLS_DEVICE);
  const struct tlsdev_ops *tlsdev_ops;
#endif;
  const struct header_ops *header_ops;
  unsigned int            flags;
  unsigned int            priv_flags;
  unsigned short          gflags;
  unsigned short          padded;
  unsigned char           operstate;
  unsigned char           link_mode;
  unsigned char           if_port;
  unsigned char           dma;
  unsigned int            mtu;
  unsigned int            min_mtu;
  unsigned int            max_mtu;
  unsigned short          type;
  unsigned short          hard_header_len;
  unsigned char           min_header_len;
  unsigned short          needed_headroom;
  unsigned short          needed_tailroom;
  unsigned char           perm_addr[MAX_ADDR_LEN];
  unsigned char           addr_assign_type;
  unsigned char           addr_len;
  unsigned short          neigh_priv_len;
  unsigned short          dev_id;
  unsigned short          dev_port;
  spinlock_t addr_list_lock;
  unsigned char           name_assign_type;
  bool uc_promisc;
  struct netdev_hw_addr_list      uc;
  struct netdev_hw_addr_list      mc;
  struct netdev_hw_addr_list      dev_addrs;
#ifdef CONFIG_SYSFS;
  struct kset             *queues_kset;
#endif;
  unsigned int            promiscuity;
  unsigned int            allmulti;
#if IS_ENABLED(CONFIG_VLAN_8021Q);
  struct vlan_info __rcu  *vlan_info;
#endif;
#if IS_ENABLED(CONFIG_NET_DSA);
  struct dsa_port         *dsa_ptr;
#endif;
#if IS_ENABLED(CONFIG_TIPC);
  struct tipc_bearer __rcu *tipc_ptr;
#endif;
#if IS_ENABLED(CONFIG_IRDA) || IS_ENABLED(CONFIG_ATALK);
  void *atalk_ptr;
#endif;
  struct in_device __rcu  *ip_ptr;
#if IS_ENABLED(CONFIG_DECNET);
  struct dn_dev __rcu     *dn_ptr;
#endif;
  struct inet6_dev __rcu  *ip6_ptr;
#if IS_ENABLED(CONFIG_AX25);
  void *ax25_ptr;
#endif;
  struct wireless_dev     *ieee80211_ptr;
  struct wpan_dev         *ieee802154_ptr;
#if IS_ENABLED(CONFIG_MPLS_ROUTING);
  struct mpls_dev __rcu   *mpls_ptr;
#endif;
  unsigned char           *dev_addr;
  struct netdev_rx_queue  *_rx;
  unsigned int            num_rx_queues;
  unsigned int            real_num_rx_queues;
  struct bpf_prog __rcu   *xdp_prog;
  unsigned long           gro_flush_timeout;
  rx_handler_func_t __rcu *rx_handler;
  void __rcu              *rx_handler_data;
#ifdef CONFIG_NET_CLS_ACT;
  struct mini_Qdisc __rcu *miniq_ingress;
#endif;
  struct netdev_queue __rcu *ingress_queue;
#ifdef CONFIG_NETFILTER_INGRESS;
  struct nf_hook_entries __rcu *nf_hooks_ingress;
#endif;
  unsigned char           broadcast[MAX_ADDR_LEN];
#ifdef CONFIG_RFS_ACCEL;
  struct cpu_rmap         *rx_cpu_rmap;
#endif;
  struct hlist_node       index_hlist;
  struct netdev_queue     *_tx ____cacheline_aligned_in_smp;
  unsigned int            num_tx_queues;
  unsigned int            real_num_tx_queues;
  struct Qdisc            *qdisc;
#ifdef CONFIG_NET_SCHED;
  unsigned long qdisc_hash[1 << ((4) - 1)];
#endif;
  unsigned int            tx_queue_len;
  spinlock_t tx_global_lock;
  int watchdog_timeo;
#ifdef CONFIG_XPS;
  struct xps_dev_maps __rcu *xps_cpus_map;
  struct xps_dev_maps __rcu *xps_rxqs_map;
#endif;
#ifdef CONFIG_NET_CLS_ACT;
  struct mini_Qdisc __rcu *miniq_egress;
#endif;
  struct timer_list       watchdog_timer;
  int __percpu            *pcpu_refcnt;
  struct list_head        todo_list;
  struct list_head        link_watch_list;
  enum {
    NETREG_UNINITIALIZED=0,
    NETREG_REGISTERED,
    NETREG_UNREGISTERING,
    NETREG_UNREGISTERED,
    NETREG_RELEASED,
    NETREG_DUMMY,
  } reg_state:8;
  bool dismantle;
  enum {
    RTNL_LINK_INITIALIZED,
    RTNL_LINK_INITIALIZING,
  } rtnl_link_state:16;
  bool needs_free_netdev;
  void (*priv_destructor)(struct net_device *dev);
#ifdef CONFIG_NETPOLL;
  struct netpoll_info __rcu       *npinfo;
#endif;
  possible_net_t nd_net;
  union {
    void *ml_priv;
    struct pcpu_lstats __percpu             *lstats;
    struct pcpu_sw_netstats __percpu        *tstats;
    struct pcpu_dstats __percpu             *dstats;
  };
#if IS_ENABLED(CONFIG_GARP);
  struct garp_port __rcu  *garp_port;
#endif;
#if IS_ENABLED(CONFIG_MRP);
  struct mrp_port __rcu   *mrp_port;
#endif;
  struct device           dev;
  const struct attribute_group *sysfs_groups[4];
  const struct attribute_group *sysfs_rx_queue_group;
  const struct rtnl_link_ops *rtnl_link_ops;
#define GSO_MAX_SIZE            65536;
  unsigned int            gso_max_size;
#define GSO_MAX_SEGS            65535;
  u16 gso_max_segs;
#ifdef CONFIG_DCB;
  const struct dcbnl_rtnl_ops *dcbnl_ops;
#endif;
  s16 num_tc;
  struct netdev_tc_txq    tc_to_txq[TC_MAX_QUEUE];
  u8 prio_tc_map[TC_BITMASK + 1];
#if IS_ENABLED(CONFIG_FCOE);
  unsigned int            fcoe_ddp_xid;
#endif;
#if IS_ENABLED(CONFIG_CGROUP_NET_PRIO);
  struct netprio_map __rcu *priomap;
#endif;
  struct phy_device       *phydev;
  struct sfp_bus          *sfp_bus;
  struct lock_class_key   *qdisc_tx_busylock;
  struct lock_class_key   *qdisc_running_key;
  bool proto_down;
  unsigned wol_enabled:1;
};

Members

name
This is the first field of the “visible” part of this structure (i.e. as seen by users in the “Space.c” file). It is the name of the interface.
name_hlist
Device name hash chain, please keep it close to name[]
ifalias
SNMP alias
mem_end
Shared memory end
mem_start
Shared memory start
base_addr
Device I/O address
irq
Device IRQ number
state
Generic network queuing layer state, see netdev_state_t
dev_list
The global list of network devices
napi_list
List entry used for polling NAPI devices
unreg_list
List entry when we are unregistering the device; see the function unregister_netdev
close_list
List entry used when we are closing the device
ptype_all
Device-specific packet handlers for all protocols
ptype_specific
Device-specific, protocol-specific packet handlers
adj_list
Directly linked devices, like slaves for bonding
features
Currently active device features
hw_features
User-changeable features
wanted_features
User-requested features
vlan_features
Mask of features inheritable by VLAN devices
hw_enc_features
Mask of features inherited by encapsulating devices This field indicates what encapsulation offloads the hardware is capable of doing, and drivers will need to set them appropriately.
mpls_features
Mask of features inheritable by MPLS
ifindex
interface index
group
The group the device belongs to
stats
Statistics struct, which was left as a legacy, use rtnl_link_stats64 instead
rx_dropped
Dropped packets by core network, do not use this in drivers
tx_dropped
Dropped packets by core network, do not use this in drivers
rx_nohandler
nohandler dropped packets by core network on inactive devices, do not use this in drivers
carrier_up_count
Number of times the carrier has been up
carrier_down_count
Number of times the carrier has been down
wireless_handlers
List of functions to handle Wireless Extensions, instead of ioctl, see <net/iw_handler.h> for details.
wireless_data
Instance data managed by the core of wireless extensions
netdev_ops
Includes several pointers to callbacks, if one wants to override the ndo_*() functions
ethtool_ops
Management operations
ndisc_ops
Includes callbacks for different IPv6 neighbour discovery handling. Necessary for e.g. 6LoWPAN.
header_ops
Includes callbacks for creating,parsing,caching,etc of Layer 2 headers.
flags
Interface flags (a la BSD)
priv_flags
Like ‘flags’ but invisible to userspace, see if.h for the definitions
gflags
Global flags ( kept as legacy )
padded
How much padding added by alloc_netdev()
operstate
RFC2863 operstate
link_mode
Mapping policy to operstate
if_port
Selectable AUI, TP, …
dma
DMA channel
mtu
Interface MTU value
min_mtu
Interface Minimum MTU value
max_mtu
Interface Maximum MTU value
type
Interface hardware type
hard_header_len
Maximum hardware header length.
min_header_len
Minimum hardware header length
needed_headroom
Extra headroom the hardware may need, but not in all cases can this be guaranteed
needed_tailroom
Extra tailroom the hardware may need, but not in all cases can this be guaranteed. Some cases also use LL_MAX_HEADER instead to allocate the skb
perm_addr
Permanent hw address
addr_assign_type
Hw address assignment type
addr_len
Hardware address length
neigh_priv_len
Used in neigh_alloc()
dev_id
Used to differentiate devices that share the same link layer address
dev_port
Used to differentiate devices that share the same function
addr_list_lock
XXX: need comments on this one
uc_promisc
Counter that indicates promiscuous mode has been enabled due to the need to listen to additional unicast addresses in a device that does not implement ndo_set_rx_mode()
uc
unicast mac addresses
mc
multicast mac addresses
dev_addrs
list of device hw addresses
queues_kset
Group of all Kobjects in the Tx and RX queues
promiscuity
Number of times the NIC is told to work in promiscuous mode; if it becomes 0 the NIC will exit promiscuous mode
allmulti
Counter, enables or disables allmulticast mode
vlan_info
VLAN info
dsa_ptr
dsa specific data
tipc_ptr
TIPC specific data
atalk_ptr
AppleTalk link
ip_ptr
IPv4 specific data
dn_ptr
DECnet specific data
ip6_ptr
IPv6 specific data
ax25_ptr
AX.25 specific data
ieee80211_ptr
IEEE 802.11 specific data, assign before registering
dev_addr
Hw address (before bcast, because most packets are unicast)
_rx
Array of RX queues
num_rx_queues
Number of RX queues allocated at register_netdev() time
real_num_rx_queues
Number of RX queues currently active in device
rx_handler
handler for received packets
rx_handler_data
XXX: need comments on this one
miniq_ingress
ingress/clsact qdisc specific data for ingress processing
ingress_queue
XXX: need comments on this one
broadcast
hw bcast address
rx_cpu_rmap
CPU reverse-mapping for RX completion interrupts, indexed by RX queue number. Assigned by driver. This must only be set if the ndo_rx_flow_steer operation is defined
index_hlist
Device index hash chain
num_tx_queues
Number of TX queues allocated at alloc_netdev_mq() time
real_num_tx_queues
Number of TX queues currently active in device
qdisc
Root qdisc from userspace point of view
tx_queue_len
Max frames per queue allowed
tx_global_lock
XXX: need comments on this one
watchdog_timeo
Represents the timeout that is used by the watchdog (see dev_watchdog())
miniq_egress
clsact qdisc specific data for egress processing
watchdog_timer
List of timers
pcpu_refcnt
Number of references to this device
todo_list
Delayed register/unregister
link_watch_list
XXX: need comments on this one
reg_state
Register/unregister state machine
dismantle
Device is going to be freed
rtnl_link_state
This enum represents the phases of creating a new link
needs_free_netdev
Should unregister perform free_netdev?
priv_destructor
Called from unregister
npinfo
XXX: need comments on this one
nd_net
Network namespace this network device is inside
{unnamed_union}
anonymous
ml_priv
Mid-layer private
lstats
Loopback statistics
tstats
Tunnel statistics
dstats
Dummy statistics
garp_port
GARP
mrp_port
MRP
dev
Class/net/name entry
sysfs_groups
Space for optional device, statistics and wireless sysfs groups
sysfs_rx_queue_group
Space for optional per-rx queue attributes
rtnl_link_ops
Rtnl_link_ops
gso_max_size
Maximum size of generic segmentation offload
gso_max_segs
Maximum number of segments that can be passed to the NIC for GSO
dcbnl_ops
Data Center Bridging netlink ops
num_tc
Number of traffic classes in the net device
tc_to_txq
XXX: need comments on this one
prio_tc_map
XXX: need comments on this one
fcoe_ddp_xid
Max exchange id for FCoE LRO by ddp
priomap
XXX: need comments on this one
phydev
Physical device may attach itself for hardware timestamping
sfp_bus
attached struct sfp_bus structure.
qdisc_tx_busylock
lockdep class annotating Qdisc->busylock spinlock
qdisc_running_key
lockdep class annotating Qdisc->running seqcount
proto_down
protocol port state information can be sent to the switch driver and used to set the phys state of the switch port.
wol_enabled
Wake-on-LAN is enabled

Description

Actually, this whole structure is a big mistake. It mixes I/O data with strictly “high-level” data, and it has to know about almost every data structure used in the INET module.

interface address info:

FIXME: cleanup struct net_device such that network protocol info moves out.

void * netdev_priv(const struct net_device * dev)

access network device private data

Parameters

const struct net_device * dev
network device

Description

Get network device private data

void netif_napi_add(struct net_device * dev, struct napi_struct * napi, int (*poll) (struct napi_struct *, int, int weight)

initialize a NAPI context

Parameters

struct net_device * dev
network device
struct napi_struct * napi
NAPI context
int (*)(struct napi_struct *, int) poll
polling function
int weight
default weight

Description

netif_napi_add() must be used to initialize a NAPI context prior to calling any of the other NAPI-related functions.

void netif_tx_napi_add(struct net_device * dev, struct napi_struct * napi, int (*poll) (struct napi_struct *, int, int weight)

initialize a NAPI context

Parameters

struct net_device * dev
network device
struct napi_struct * napi
NAPI context
int (*)(struct napi_struct *, int) poll
polling function
int weight
default weight

Description

This variant of netif_napi_add() should be used from drivers using NAPI to exclusively poll a TX queue. This will avoid we add it into napi_hash[], thus polluting this hash table.

void netif_napi_del(struct napi_struct * napi)

remove a NAPI context

Parameters

struct napi_struct * napi
NAPI context

Description

netif_napi_del() removes a NAPI context from the network device NAPI list
void netif_start_queue(struct net_device * dev)

allow transmit

Parameters

struct net_device * dev
network device

Description

Allow upper layers to call the device hard_start_xmit routine.
void netif_wake_queue(struct net_device * dev)

restart transmit

Parameters

struct net_device * dev
network device

Description

Allow upper layers to call the device hard_start_xmit routine. Used for flow control when transmit resources are available.
void netif_stop_queue(struct net_device * dev)

stop transmitted packets

Parameters

struct net_device * dev
network device

Description

Stop upper layers calling the device hard_start_xmit routine. Used for flow control when transmit resources are unavailable.
bool netif_queue_stopped(const struct net_device * dev)

test if transmit queue is flowblocked

Parameters

const struct net_device * dev
network device

Description

Test if transmit queue on device is currently unable to send.
void netdev_txq_bql_enqueue_prefetchw(struct netdev_queue * dev_queue)

prefetch bql data for write

Parameters

struct netdev_queue * dev_queue
pointer to transmit queue

Description

BQL enabled drivers might use this helper in their ndo_start_xmit(), to give appropriate hint to the CPU.

void netdev_txq_bql_complete_prefetchw(struct netdev_queue * dev_queue)

prefetch bql data for write

Parameters

struct netdev_queue * dev_queue
pointer to transmit queue

Description

BQL enabled drivers might use this helper in their TX completion path, to give appropriate hint to the CPU.

void netdev_sent_queue(struct net_device * dev, unsigned int bytes)

report the number of bytes queued to hardware

Parameters

struct net_device * dev
network device
unsigned int bytes
number of bytes queued to the hardware device queue

Description

Report the number of bytes queued for sending/completion to the network device hardware queue. bytes should be a good approximation and should exactly match netdev_completed_queue() bytes
void netdev_completed_queue(struct net_device * dev, unsigned int pkts, unsigned int bytes)

report bytes and packets completed by device

Parameters

struct net_device * dev
network device
unsigned int pkts
actual number of packets sent over the medium
unsigned int bytes
actual number of bytes sent over the medium

Description

Report the number of bytes and packets transmitted by the network device hardware queue over the physical medium, bytes must exactly match the bytes amount passed to netdev_sent_queue()
void netdev_reset_queue(struct net_device * dev_queue)

reset the packets and bytes count of a network device

Parameters

struct net_device * dev_queue
network device

Description

Reset the bytes and packet count of a network device and clear the software flow control OFF bit for this network device
u16 netdev_cap_txqueue(struct net_device * dev, u16 queue_index)

check if selected tx queue exceeds device queues

Parameters

struct net_device * dev
network device
u16 queue_index
given tx queue index

Description

Returns 0 if given tx queue index >= number of device tx queues, otherwise returns the originally passed tx queue index.
bool netif_running(const struct net_device * dev)

test if up

Parameters

const struct net_device * dev
network device

Description

Test if the device has been brought up.
void netif_start_subqueue(struct net_device * dev, u16 queue_index)

allow sending packets on subqueue

Parameters

struct net_device * dev
network device
u16 queue_index
sub queue index

Description

Start individual transmit queue of a device with multiple transmit queues.

void netif_stop_subqueue(struct net_device * dev, u16 queue_index)

stop sending packets on subqueue

Parameters

struct net_device * dev
network device
u16 queue_index
sub queue index

Description

Stop individual transmit queue of a device with multiple transmit queues.

bool __netif_subqueue_stopped(const struct net_device * dev, u16 queue_index)

test status of subqueue

Parameters

const struct net_device * dev
network device
u16 queue_index
sub queue index

Description

Check individual transmit queue of a device with multiple transmit queues.

void netif_wake_subqueue(struct net_device * dev, u16 queue_index)

allow sending packets on subqueue

Parameters

struct net_device * dev
network device
u16 queue_index
sub queue index

Description

Resume individual transmit queue of a device with multiple transmit queues.

bool netif_attr_test_mask(unsigned long j, const unsigned long * mask, unsigned int nr_bits)

Test a CPU or Rx queue set in a mask

Parameters

unsigned long j
CPU/Rx queue index
const unsigned long * mask
bitmask of all cpus/rx queues
unsigned int nr_bits
number of bits in the bitmask

Description

Test if a CPU or Rx queue index is set in a mask of all CPU/Rx queues.

bool netif_attr_test_online(unsigned long j, const unsigned long * online_mask, unsigned int nr_bits)

Test for online CPU/Rx queue

Parameters

unsigned long j
CPU/Rx queue index
const unsigned long * online_mask
bitmask for CPUs/Rx queues that are online
unsigned int nr_bits
number of bits in the bitmask

Description

Returns true if a CPU/Rx queue is online.

unsigned int netif_attrmask_next(int n, const unsigned long * srcp, unsigned int nr_bits)

get the next CPU/Rx queue in a cpu/Rx queues mask

Parameters

int n
CPU/Rx queue index
const unsigned long * srcp
the cpumask/Rx queue mask pointer
unsigned int nr_bits
number of bits in the bitmask

Description

Returns >= nr_bits if no further CPUs/Rx queues set.

int netif_attrmask_next_and(int n, const unsigned long * src1p, const unsigned long * src2p, unsigned int nr_bits)

get the next CPU/Rx queue in *src1p & *src2p

Parameters

int n
CPU/Rx queue index
const unsigned long * src1p
the first CPUs/Rx queues mask pointer
const unsigned long * src2p
the second CPUs/Rx queues mask pointer
unsigned int nr_bits
number of bits in the bitmask

Description

Returns >= nr_bits if no further CPUs/Rx queues set in both.

bool netif_is_multiqueue(const struct net_device * dev)

test if device has multiple transmit queues

Parameters

const struct net_device * dev
network device

Description

Check if device has multiple transmit queues

void dev_put(struct net_device * dev)

release reference to device

Parameters

struct net_device * dev
network device

Description

Release reference to device to allow it to be freed.

void dev_hold(struct net_device * dev)

get reference to device

Parameters

struct net_device * dev
network device

Description

Hold reference to device to keep it from being freed.

bool netif_carrier_ok(const struct net_device * dev)

test if carrier present

Parameters

const struct net_device * dev
network device

Description

Check if carrier is present on device

void netif_dormant_on(struct net_device * dev)

mark device as dormant.

Parameters

struct net_device * dev
network device

Description

Mark device as dormant (as per RFC2863).

The dormant state indicates that the relevant interface is not actually in a condition to pass packets (i.e., it is not ‘up’) but is in a “pending” state, waiting for some external event. For “on- demand” interfaces, this new state identifies the situation where the interface is waiting for events to place it in the up state.

void netif_dormant_off(struct net_device * dev)

set device as not dormant.

Parameters

struct net_device * dev
network device

Description

Device is not in dormant state.

bool netif_dormant(const struct net_device * dev)

test if device is dormant

Parameters

const struct net_device * dev
network device

Description

Check if device is dormant.

bool netif_oper_up(const struct net_device * dev)

test if device is operational

Parameters

const struct net_device * dev
network device

Description

Check if carrier is operational

bool netif_device_present(struct net_device * dev)

is device available or removed

Parameters

struct net_device * dev
network device

Description

Check if device has not been removed from system.

void netif_tx_lock(struct net_device * dev)

grab network device transmit lock

Parameters

struct net_device * dev
network device

Description

Get network device transmit lock

int __dev_uc_sync(struct net_device * dev, int (*sync) (struct net_device *, const unsigned char *, int (*unsync) (struct net_device *, const unsigned char *)

Synchonize device’s unicast list

Parameters

struct net_device * dev
device to sync
int (*)(struct net_device *, const unsigned char *) sync
function to call if address should be added
int (*)(struct net_device *, const unsigned char *) unsync
function to call if address should be removed

Description

Add newly added addresses to the interface, and release addresses that have been deleted.
void __dev_uc_unsync(struct net_device * dev, int (*unsync) (struct net_device *, const unsigned char *)

Remove synchronized addresses from device

Parameters

struct net_device * dev
device to sync
int (*)(struct net_device *, const unsigned char *) unsync
function to call if address should be removed

Description

Remove all addresses that were added to the device by dev_uc_sync().
int __dev_mc_sync(struct net_device * dev, int (*sync) (struct net_device *, const unsigned char *, int (*unsync) (struct net_device *, const unsigned char *)

Synchonize device’s multicast list

Parameters

struct net_device * dev
device to sync
int (*)(struct net_device *, const unsigned char *) sync
function to call if address should be added
int (*)(struct net_device *, const unsigned char *) unsync
function to call if address should be removed

Description

Add newly added addresses to the interface, and release addresses that have been deleted.
void __dev_mc_unsync(struct net_device * dev, int (*unsync) (struct net_device *, const unsigned char *)

Remove synchronized addresses from device

Parameters

struct net_device * dev
device to sync
int (*)(struct net_device *, const unsigned char *) unsync
function to call if address should be removed

Description

Remove all addresses that were added to the device by dev_mc_sync().

PHY Support

void phy_print_status(struct phy_device * phydev)

Convenience function to print out the current phy status

Parameters

struct phy_device * phydev
the phy_device struct
int phy_restart_aneg(struct phy_device * phydev)

restart auto-negotiation

Parameters

struct phy_device * phydev
target phy_device struct

Description

Restart the autonegotiation on phydev. Returns >= 0 on success or negative errno on error.

int phy_aneg_done(struct phy_device * phydev)

return auto-negotiation status

Parameters

struct phy_device * phydev
target phy_device struct

Description

Return the auto-negotiation status from this phydev Returns > 0 on success or < 0 on error. 0 means that auto-negotiation is still pending.

int phy_ethtool_sset(struct phy_device * phydev, struct ethtool_cmd * cmd)

generic ethtool sset function, handles all the details

Parameters

struct phy_device * phydev
target phy_device struct
struct ethtool_cmd * cmd
ethtool_cmd

Description

A few notes about parameter checking:

  • We don’t set port or transceiver, so we don’t care what they were set to.
  • phy_start_aneg() will make sure forced settings are sane, and choose the next best ones from the ones selected, so we don’t care if ethtool tries to give us bad values.
int phy_mii_ioctl(struct phy_device * phydev, struct ifreq * ifr, int cmd)

generic PHY MII ioctl interface

Parameters

struct phy_device * phydev
the phy_device struct
struct ifreq * ifr
struct ifreq for socket ioctl’s
int cmd
ioctl cmd to execute

Description

Note that this function is currently incompatible with the PHYCONTROL layer. It changes registers without regard to current state. Use at own risk.

int phy_start_aneg(struct phy_device * phydev)

start auto-negotiation for this PHY device

Parameters

struct phy_device * phydev
the phy_device struct

Description

Sanitizes the settings (if we’re not autonegotiating
them), and then calls the driver’s config_aneg function. If the PHYCONTROL Layer is operating, we change the state to reflect the beginning of Auto-negotiation or forcing.
int phy_speed_down(struct phy_device * phydev, bool sync)

set speed to lowest speed supported by both link partners

Parameters

struct phy_device * phydev
the phy_device struct
bool sync
perform action synchronously

Description

Typically used to save energy when waiting for a WoL packet

WARNING: Setting sync to false may cause the system being unable to suspend in case the PHY generates an interrupt when finishing the autonegotiation. This interrupt may wake up the system immediately after suspend. Therefore use sync = false only if you’re sure it’s safe with the respective network chip.

int phy_speed_up(struct phy_device * phydev)

(re)set advertised speeds to all supported speeds

Parameters

struct phy_device * phydev
the phy_device struct

Description

Used to revert the effect of phy_speed_down

void phy_start_machine(struct phy_device * phydev)

start PHY state machine tracking

Parameters

struct phy_device * phydev
the phy_device struct

Description

The PHY infrastructure can run a state machine
which tracks whether the PHY is starting up, negotiating, etc. This function starts the delayed workqueue which tracks the state of the PHY. If you want to maintain your own state machine, do not call this function.
int phy_start_interrupts(struct phy_device * phydev)

request and enable interrupts for a PHY device

Parameters

struct phy_device * phydev
target phy_device struct

Description

Request the interrupt for the given PHY.
If this fails, then we set irq to PHY_POLL. Otherwise, we enable the interrupts in the PHY. This should only be called with a valid IRQ number. Returns 0 on success or < 0 on error.
int phy_stop_interrupts(struct phy_device * phydev)

disable interrupts from a PHY device

Parameters

struct phy_device * phydev
target phy_device struct
void phy_stop(struct phy_device * phydev)

Bring down the PHY link, and stop checking the status

Parameters

struct phy_device * phydev
target phy_device struct
void phy_start(struct phy_device * phydev)

start or restart a PHY device

Parameters

struct phy_device * phydev
target phy_device struct

Description

Indicates the attached device’s readiness to
handle PHY-related work. Used during startup to start the PHY, and after a call to phy_stop() to resume operation. Also used to indicate the MDIO bus has cleared an error condition.
void phy_mac_interrupt(struct phy_device * phydev)

MAC says the link has changed

Parameters

struct phy_device * phydev
phy_device struct with changed link

Description

The MAC layer is able to indicate there has been a change in the PHY link status. Trigger the state machine and work a work queue.

int phy_init_eee(struct phy_device * phydev, bool clk_stop_enable)

init and check the EEE feature

Parameters

struct phy_device * phydev
target phy_device struct
bool clk_stop_enable
PHY may stop the clock during LPI

Description

it checks if the Energy-Efficient Ethernet (EEE) is supported by looking at the MMD registers 3.20 and 7.60/61 and it programs the MMD register 3.0 setting the “Clock stop enable” bit if required.

int phy_get_eee_err(struct phy_device * phydev)

report the EEE wake error count

Parameters

struct phy_device * phydev
target phy_device struct

Description

it is to report the number of time where the PHY failed to complete its normal wake sequence.

int phy_ethtool_get_eee(struct phy_device * phydev, struct ethtool_eee * data)

get EEE supported and status

Parameters

struct phy_device * phydev
target phy_device struct
struct ethtool_eee * data
ethtool_eee data

Description

it reportes the Supported/Advertisement/LP Advertisement capabilities.

int phy_ethtool_set_eee(struct phy_device * phydev, struct ethtool_eee * data)

set EEE supported and status

Parameters

struct phy_device * phydev
target phy_device struct
struct ethtool_eee * data
ethtool_eee data

Description

it is to program the Advertisement EEE register.

int phy_clear_interrupt(struct phy_device * phydev)

Ack the phy device’s interrupt

Parameters

struct phy_device * phydev
the phy_device struct

Description

If the phydev driver has an ack_interrupt function, call it to ack and clear the phy device’s interrupt.

Returns 0 on success or < 0 on error.

int phy_config_interrupt(struct phy_device * phydev, u32 interrupts)

configure the PHY device for the requested interrupts

Parameters

struct phy_device * phydev
the phy_device struct
u32 interrupts
interrupt flags to configure for this phydev

Description

Returns 0 on success or < 0 on error.

const struct phy_setting * phy_find_valid(int speed, int duplex, u32 supported)

find a PHY setting that matches the requested parameters

Parameters

int speed
desired speed
int duplex
desired duplex
u32 supported
mask of supported link modes

Description

Locate a supported phy setting that is, in priority order: - an exact match for the specified speed and duplex mode - a match for the specified speed, or slower speed - the slowest supported speed Returns the matched phy_setting entry, or NULL if no supported phy settings were found.

unsigned int phy_supported_speeds(struct phy_device * phy, unsigned int * speeds, unsigned int size)

return all speeds currently supported by a phy device

Parameters

struct phy_device * phy
The phy device to return supported speeds of.
unsigned int * speeds
buffer to store supported speeds in.
unsigned int size
size of speeds buffer.

Description

Returns the number of supported speeds, and fills the speeds buffer with the supported speeds. If speeds buffer is too small to contain all currently supported speeds, will return as many speeds as can fit.

bool phy_check_valid(int speed, int duplex, u32 features)

check if there is a valid PHY setting which matches speed, duplex, and feature mask

Parameters

int speed
speed to match
int duplex
duplex to match
u32 features
A mask of the valid settings

Description

Returns true if there is a valid setting, false otherwise.

void phy_sanitize_settings(struct phy_device * phydev)

make sure the PHY is set to supported speed and duplex

Parameters

struct phy_device * phydev
the target phy_device struct

Description

Make sure the PHY is set to supported speeds and
duplexes. Drop down by one in this order: 1000/FULL, 1000/HALF, 100/FULL, 100/HALF, 10/FULL, 10/HALF.
void phy_trigger_machine(struct phy_device * phydev)

trigger the state machine to run

Parameters

struct phy_device * phydev
the phy_device struct

Description

There has been a change in state which requires that the
state machine runs.
void phy_stop_machine(struct phy_device * phydev)

stop the PHY state machine tracking

Parameters

struct phy_device * phydev
target phy_device struct

Description

Stops the state machine delayed workqueue, sets the
state to UP (unless it wasn’t up yet). This function must be called BEFORE phy_detach.
void phy_error(struct phy_device * phydev)

enter HALTED state for this PHY device

Parameters

struct phy_device * phydev
target phy_device struct

Description

Moves the PHY to the HALTED state in response to a read or write error, and tells the controller the link is down. Must not be called from interrupt context, or while the phydev->lock is held.

int phy_disable_interrupts(struct phy_device * phydev)

Disable the PHY interrupts from the PHY side

Parameters

struct phy_device * phydev
target phy_device struct
irqreturn_t phy_change(struct phy_device * phydev)

Called by the phy_interrupt to handle PHY changes

Parameters

struct phy_device * phydev
phy_device struct that interrupted
void phy_change_work(struct work_struct * work)

Scheduled by the phy_mac_interrupt to handle PHY changes

Parameters

struct work_struct * work
work_struct that describes the work to be done
irqreturn_t phy_interrupt(int irq, void * phy_dat)

PHY interrupt handler

Parameters

int irq
interrupt line
void * phy_dat
phy_device pointer

Description

When a PHY interrupt occurs, the handler disables interrupts, and uses phy_change to handle the interrupt.

int phy_enable_interrupts(struct phy_device * phydev)

Enable the interrupts from the PHY side

Parameters

struct phy_device * phydev
target phy_device struct
void phy_state_machine(struct work_struct * work)

Handle the state machine

Parameters

struct work_struct * work
work_struct that describes the work to be done
int phy_register_fixup(const char * bus_id, u32 phy_uid, u32 phy_uid_mask, int (*run) (struct phy_device *)

creates a new phy_fixup and adds it to the list

Parameters

const char * bus_id
A string which matches phydev->mdio.dev.bus_id (or PHY_ANY_ID)
u32 phy_uid
Used to match against phydev->phy_id (the UID of the PHY) It can also be PHY_ANY_UID
u32 phy_uid_mask
Applied to phydev->phy_id and fixup->phy_uid before comparison
int (*)(struct phy_device *) run
The actual code to be run when a matching PHY is found
int phy_unregister_fixup(const char * bus_id, u32 phy_uid, u32 phy_uid_mask)

remove a phy_fixup from the list

Parameters

const char * bus_id
A string matches fixup->bus_id (or PHY_ANY_ID) in phy_fixup_list
u32 phy_uid
A phy id matches fixup->phy_id (or PHY_ANY_UID) in phy_fixup_list
u32 phy_uid_mask
Applied to phy_uid and fixup->phy_uid before comparison
struct phy_device * get_phy_device(struct mii_bus * bus, int addr, bool is_c45)

reads the specified PHY device and returns its phy_device struct

Parameters

struct mii_bus * bus
the target MII bus
int addr
PHY address on the MII bus
bool is_c45
If true the PHY uses the 802.3 clause 45 protocol

Description

Reads the ID registers of the PHY at addr on the
bus, then allocates and returns the phy_device to represent it.
int phy_device_register(struct phy_device * phydev)

Register the phy device on the MDIO bus

Parameters

struct phy_device * phydev
phy_device structure to be added to the MDIO bus
void phy_device_remove(struct phy_device * phydev)

Remove a previously registered phy device from the MDIO bus

Parameters

struct phy_device * phydev
phy_device structure to remove

Description

This doesn’t free the phy_device itself, it merely reverses the effects of phy_device_register(). Use phy_device_free() to free the device after calling this function.

struct phy_device * phy_find_first(struct mii_bus * bus)

finds the first PHY device on the bus

Parameters

struct mii_bus * bus
the target MII bus
int phy_connect_direct(struct net_device * dev, struct phy_device * phydev, void (*handler) (struct net_device *, phy_interface_t interface)

connect an ethernet device to a specific phy_device

Parameters

struct net_device * dev
the network device to connect
struct phy_device * phydev
the pointer to the phy device
void (*)(struct net_device *) handler
callback function for state change notifications
phy_interface_t interface
PHY device’s interface
struct phy_device * phy_connect(struct net_device * dev, const char * bus_id, void (*handler) (struct net_device *, phy_interface_t interface)

connect an ethernet device to a PHY device

Parameters

struct net_device * dev
the network device to connect
const char * bus_id
the id string of the PHY device to connect
void (*)(struct net_device *) handler
callback function for state change notifications
phy_interface_t interface
PHY device’s interface

Description

Convenience function for connecting ethernet
devices to PHY devices. The default behavior is for the PHY infrastructure to handle everything, and only notify the connected driver when the link status changes. If you don’t want, or can’t use the provided functionality, you may choose to call only the subset of functions which provide the desired functionality.
void phy_disconnect(struct phy_device * phydev)

disable interrupts, stop state machine, and detach a PHY device

Parameters

struct phy_device * phydev
target phy_device struct
int phy_attach_direct(struct net_device * dev, struct phy_device * phydev, u32 flags, phy_interface_t interface)

attach a network device to a given PHY device pointer

Parameters

struct net_device * dev
network device to attach
struct phy_device * phydev
Pointer to phy_device to attach
u32 flags
PHY device’s dev_flags
phy_interface_t interface
PHY device’s interface

Description

Called by drivers to attach to a particular PHY
device. The phy_device is found, and properly hooked up to the phy_driver. If no driver is attached, then a generic driver is used. The phy_device is given a ptr to the attaching device, and given a callback for link status change. The phy_device is returned to the attaching driver. This function takes a reference on the phy device.
struct phy_device * phy_attach(struct net_device * dev, const char * bus_id, phy_interface_t interface)

attach a network device to a particular PHY device

Parameters

struct net_device * dev
network device to attach
const char * bus_id
Bus ID of PHY device to attach
phy_interface_t interface
PHY device’s interface

Description

Same as phy_attach_direct() except that a PHY bus_id
string is passed instead of a pointer to a struct phy_device.
void phy_detach(struct phy_device * phydev)

detach a PHY device from its network device

Parameters

struct phy_device * phydev
target phy_device struct

Description

This detaches the phy device from its network device and the phy driver, and drops the reference count taken in phy_attach_direct().

int phy_reset_after_clk_enable(struct phy_device * phydev)

perform a PHY reset if needed

Parameters

struct phy_device * phydev
target phy_device struct

Description

Some PHYs are known to need a reset after their refclk was
enabled. This function evaluates the flags and perform the reset if it’s needed. Returns < 0 on error, 0 if the phy wasn’t reset and 1 if the phy was reset.
int genphy_setup_forced(struct phy_device * phydev)

configures/forces speed/duplex from phydev

Parameters

struct phy_device * phydev
target phy_device struct

Description

Configures MII_BMCR to force speed/duplex
to the values in phydev. Assumes that the values are valid. Please see phy_sanitize_settings().
int genphy_restart_aneg(struct phy_device * phydev)

Enable and Restart Autonegotiation

Parameters

struct phy_device * phydev
target phy_device struct
int genphy_config_aneg(struct phy_device * phydev)

restart auto-negotiation or write BMCR

Parameters

struct phy_device * phydev
target phy_device struct

Description

If auto-negotiation is enabled, we configure the
advertising, and then restart auto-negotiation. If it is not enabled, then we write the BMCR.
int genphy_aneg_done(struct phy_device * phydev)

return auto-negotiation status

Parameters

struct phy_device * phydev
target phy_device struct

Description

Reads the status register and returns 0 either if
auto-negotiation is incomplete, or if there was an error. Returns BMSR_ANEGCOMPLETE if auto-negotiation is done.

update link status in phydev

Parameters

struct phy_device * phydev
target phy_device struct

Description

Update the value in phydev->link to reflect the
current link value. In order to do this, we need to read the status register twice, keeping the second value.
int genphy_read_status(struct phy_device * phydev)

check the link status and update current link state

Parameters

struct phy_device * phydev
target phy_device struct

Description

Check the link, then figure out the current state
by comparing what we advertise with what the link partner advertises. Start by checking the gigabit possibilities, then move on to 10/100.
int genphy_soft_reset(struct phy_device * phydev)

software reset the PHY via BMCR_RESET bit

Parameters

struct phy_device * phydev
target phy_device struct

Description

Perform a software PHY reset using the standard BMCR_RESET bit and poll for the reset bit to be cleared.

Return

0 on success, < 0 on failure

Remove a supported link mode

Parameters

struct phy_device * phydev
phy_device structure to remove link mode from
u32 link_mode
Link mode to be removed

Description

Some MACs don’t support all link modes which the PHY does. e.g. a 1G MAC often does not support 1000Half. Add a helper to remove a link mode.

void phy_support_sym_pause(struct phy_device * phydev)

Enable support of symmetrical pause

Parameters

struct phy_device * phydev
target phy_device struct

Description

Called by the MAC to indicate is supports symmetrical Pause, but not asym pause.

void phy_support_asym_pause(struct phy_device * phydev)

Enable support of asym pause

Parameters

struct phy_device * phydev
target phy_device struct

Description

Called by the MAC to indicate is supports Asym Pause.

void phy_set_sym_pause(struct phy_device * phydev, bool rx, bool tx, bool autoneg)

Configure symmetric Pause

Parameters

struct phy_device * phydev
target phy_device struct
bool rx
Receiver Pause is supported
bool tx
Transmit Pause is supported
bool autoneg
Auto neg should be used

Description

Configure advertised Pause support depending on if receiver pause and pause auto neg is supported. Generally called from the set_pauseparam .ndo.

void phy_set_asym_pause(struct phy_device * phydev, bool rx, bool tx)

Configure Pause and Asym Pause

Parameters

struct phy_device * phydev
target phy_device struct
bool rx
Receiver Pause is supported
bool tx
Transmit Pause is supported

Description

Configure advertised Pause support depending on if transmit and receiver pause is supported. If there has been a change in adverting, trigger a new autoneg. Generally called from the set_pauseparam .ndo.

bool phy_validate_pause(struct phy_device * phydev, struct ethtool_pauseparam * pp)

Test if the PHY/MAC support the pause configuration

Parameters

struct phy_device * phydev
phy_device struct
struct ethtool_pauseparam * pp
requested pause configuration

Description

Test if the PHY/MAC combination supports the Pause configuration the user is requesting. Returns True if it is supported, false otherwise.

int phy_driver_register(struct phy_driver * new_driver, struct module * owner)

register a phy_driver with the PHY layer

Parameters

struct phy_driver * new_driver
new phy_driver to register
struct module * owner
module owning this PHY
int get_phy_c45_ids(struct mii_bus * bus, int addr, u32 * phy_id, struct phy_c45_device_ids * c45_ids)

reads the specified addr for its 802.3-c45 IDs.

Parameters

struct mii_bus * bus
the target MII bus
int addr
PHY address on the MII bus
u32 * phy_id
where to store the ID retrieved.
struct phy_c45_device_ids * c45_ids
where to store the c45 ID information.

Description

If the PHY devices-in-package appears to be valid, it and the corresponding identifiers are stored in c45_ids, zero is stored in phy_id. Otherwise 0xffffffff is stored in phy_id. Returns zero on success.
int get_phy_id(struct mii_bus * bus, int addr, u32 * phy_id, bool is_c45, struct phy_c45_device_ids * c45_ids)

reads the specified addr for its ID.

Parameters

struct mii_bus * bus
the target MII bus
int addr
PHY address on the MII bus
u32 * phy_id
where to store the ID retrieved.
bool is_c45
If true the PHY uses the 802.3 clause 45 protocol
struct phy_c45_device_ids * c45_ids
where to store the c45 ID information.

Description

In the case of a 802.3-c22 PHY, reads the ID registers

of the PHY at addr on the bus, stores it in phy_id and returns zero on success.

In the case of a 802.3-c45 PHY, get_phy_c45_ids() is invoked, and its return value is in turn returned.

prepares the PHY layer to monitor link status

Parameters

struct phy_device * phydev
target phy_device struct
void (*)(struct net_device *) handler
callback function for link status change notifications

Description

Tells the PHY infrastructure to handle the
gory details on monitoring link status (whether through polling or an interrupt), and to call back to the connected device driver when the link status changes. If you want to monitor your own link state, don’t call this function.
int phy_poll_reset(struct phy_device * phydev)

Safely wait until a PHY reset has properly completed

Parameters

struct phy_device * phydev
The PHY device to poll

Description

According to IEEE 802.3, Section 2, Subsection 22.2.4.1.1, as

published in 2008, a PHY reset may take up to 0.5 seconds. The MII BMCR register must be polled until the BMCR_RESET bit clears.

Furthermore, any attempts to write to PHY registers may have no effect or even generate MDIO bus errors until this is complete.

Some PHYs (such as the Marvell 88E1111) don’t entirely conform to the standard and do not fully reset after the BMCR_RESET bit is set, and may even REQUIRE a soft-reset to properly restart autonegotiation. In an effort to support such broken PHYs, this function is separate from the standard phy_init_hw() which will zero all the other bits in the BMCR and reapply all driver-specific and board-specific fixups.

int genphy_config_advert(struct phy_device * phydev)

sanitize and advertise auto-negotiation parameters

Parameters

struct phy_device * phydev
target phy_device struct

Description

Writes MII_ADVERTISE with the appropriate values,
after sanitizing the values to make sure we only advertise what is supported. Returns < 0 on error, 0 if the PHY’s advertisement hasn’t changed, and > 0 if it has changed.
int genphy_config_eee_advert(struct phy_device * phydev)

disable unwanted eee mode advertisement

Parameters

struct phy_device * phydev
target phy_device struct

Description

Writes MDIO_AN_EEE_ADV after disabling unsupported energy
efficent ethernet modes. Returns 0 if the PHY’s advertisement hasn’t changed, and 1 if it has changed.
int phy_probe(struct device * dev)

probe and init a PHY device

Parameters

struct device * dev
device to probe and init

Description

Take care of setting up the phy_device structure,
set the state to READY (the driver’s init function should set it to STARTING if needed).
struct mii_bus * mdiobus_alloc_size(size_t size)

allocate a mii_bus structure

Parameters

size_t size
extra amount of memory to allocate for private storage. If non-zero, then bus->priv is points to that memory.

Description

called by a bus driver to allocate an mii_bus structure to fill in.

struct mii_bus * devm_mdiobus_alloc_size(struct device * dev, int sizeof_priv)

Resource-managed mdiobus_alloc_size()

Parameters

struct device * dev
Device to allocate mii_bus for
int sizeof_priv
Space to allocate for private structure.

Description

Managed mdiobus_alloc_size. mii_bus allocated with this function is automatically freed on driver detach.

If an mii_bus allocated with this function needs to be freed separately, devm_mdiobus_free() must be used.

Return

Pointer to allocated mii_bus on success, NULL on failure.

void devm_mdiobus_free(struct device * dev, struct mii_bus * bus)

Resource-managed mdiobus_free()

Parameters

struct device * dev
Device this mii_bus belongs to
struct mii_bus * bus
the mii_bus associated with the device

Description

Free mii_bus allocated with devm_mdiobus_alloc_size().

struct mii_bus * of_mdio_find_bus(struct device_node * mdio_bus_np)

Given an mii_bus node, find the mii_bus.

Parameters

struct device_node * mdio_bus_np
Pointer to the mii_bus.

Description

Returns a reference to the mii_bus, or NULL if none found. The embedded struct device will have its reference count incremented, and this must be put once the bus is finished with.

Because the association of a device_node and mii_bus is made via of_mdiobus_register(), the mii_bus cannot be found before it is registered with of_mdiobus_register().

int __mdiobus_register(struct mii_bus * bus, struct module * owner)

bring up all the PHYs on a given bus and attach them to bus

Parameters

struct mii_bus * bus
target mii_bus
struct module * owner
module containing bus accessor functions

Description

Called by a bus driver to bring up all the PHYs
on a given bus, and attach them to the bus. Drivers should use mdiobus_register() rather than __mdiobus_register() unless they need to pass a specific owner module. MDIO devices which are not PHYs will not be brought up by this function. They are expected to to be explicitly listed in DT and instantiated by of_mdiobus_register().

Returns 0 on success or < 0 on error.

void mdiobus_free(struct mii_bus * bus)

free a struct mii_bus

Parameters

struct mii_bus * bus
mii_bus to free

Description

This function releases the reference to the underlying device object in the mii_bus. If this is the last reference, the mii_bus will be freed.

struct phy_device * mdiobus_scan(struct mii_bus * bus, int addr)

scan a bus for MDIO devices.

Parameters

struct mii_bus * bus
mii_bus to scan
int addr
address on bus to scan

Description

This function scans the MDIO bus, looking for devices which can be identified using a vendor/product ID in registers 2 and 3. Not all MDIO devices have such registers, but PHY devices typically do. Hence this function assumes anything found is a PHY, or can be treated as a PHY. Other MDIO devices, such as switches, will probably not be found during the scan.

int __mdiobus_read(struct mii_bus * bus, int addr, u32 regnum)

Unlocked version of the mdiobus_read function

Parameters

struct mii_bus * bus
the mii_bus struct
int addr
the phy address
u32 regnum
register number to read

Description

Read a MDIO bus register. Caller must hold the mdio bus lock.

NOTE

MUST NOT be called from interrupt context.

int __mdiobus_write(struct mii_bus * bus, int addr, u32 regnum, u16 val)

Unlocked version of the mdiobus_write function

Parameters

struct mii_bus * bus
the mii_bus struct
int addr
the phy address
u32 regnum
register number to write
u16 val
value to write to regnum

Description

Write a MDIO bus register. Caller must hold the mdio bus lock.

NOTE

MUST NOT be called from interrupt context.

int mdiobus_read_nested(struct mii_bus * bus, int addr, u32 regnum)

Nested version of the mdiobus_read function

Parameters

struct mii_bus * bus
the mii_bus struct
int addr
the phy address
u32 regnum
register number to read

Description

In case of nested MDIO bus access avoid lockdep false positives by using mutex_lock_nested().

NOTE

MUST NOT be called from interrupt context, because the bus read/write functions may wait for an interrupt to conclude the operation.

int mdiobus_read(struct mii_bus * bus, int addr, u32 regnum)

Convenience function for reading a given MII mgmt register

Parameters

struct mii_bus * bus
the mii_bus struct
int addr
the phy address
u32 regnum
register number to read

NOTE

MUST NOT be called from interrupt context, because the bus read/write functions may wait for an interrupt to conclude the operation.

int mdiobus_write_nested(struct mii_bus * bus, int addr, u32 regnum, u16 val)

Nested version of the mdiobus_write function

Parameters

struct mii_bus * bus
the mii_bus struct
int addr
the phy address
u32 regnum
register number to write
u16 val
value to write to regnum

Description

In case of nested MDIO bus access avoid lockdep false positives by using mutex_lock_nested().

NOTE

MUST NOT be called from interrupt context, because the bus read/write functions may wait for an interrupt to conclude the operation.

int mdiobus_write(struct mii_bus * bus, int addr, u32 regnum, u16 val)

Convenience function for writing a given MII mgmt register

Parameters

struct mii_bus * bus
the mii_bus struct
int addr
the phy address
u32 regnum
register number to write
u16 val
value to write to regnum

NOTE

MUST NOT be called from interrupt context, because the bus read/write functions may wait for an interrupt to conclude the operation.

void mdiobus_release(struct device * d)

mii_bus device release callback

Parameters

struct device * d
the target struct device that contains the mii_bus

Description

called when the last reference to an mii_bus is dropped, to free the underlying memory.

int mdiobus_create_device(struct mii_bus * bus, struct mdio_board_info * bi)

create a full MDIO device given a mdio_board_info structure

Parameters

struct mii_bus * bus
MDIO bus to create the devices on
struct mdio_board_info * bi
mdio_board_info structure describing the devices

Description

Returns 0 on success or < 0 on error.

int mdio_bus_match(struct device * dev, struct device_driver * drv)

determine if given MDIO driver supports the given MDIO device

Parameters

struct device * dev
target MDIO device
struct device_driver * drv
given MDIO driver

Description

Given a MDIO device, and a MDIO driver, return 1 if
the driver supports the device. Otherwise, return 0. This may require calling the devices own match function, since different classes of MDIO devices have different match criteria.

SFP support

struct sfp_bus

internal representation of a sfp bus

Definition

struct sfp_bus {
};

Members

struct sfp_eeprom_id

raw SFP module identification information

Definition

struct sfp_eeprom_id {
  struct sfp_eeprom_base base;
  struct sfp_eeprom_ext ext;
};

Members

base
base SFP module identification structure
ext
extended SFP module identification structure

Description

See the SFF-8472 specification and related documents for the definition of these structure members. This can be obtained from ftp://ftp.seagate.com/sff

struct sfp_upstream_ops

upstream operations structure

Definition

struct sfp_upstream_ops {
  int (*module_insert)(void *priv, const struct sfp_eeprom_id *id);
  void (*module_remove)(void *priv);
  void (*link_down)(void *priv);
  void (*link_up)(void *priv);
  int (*connect_phy)(void *priv, struct phy_device *);
  void (*disconnect_phy)(void *priv);
};

Members

module_insert
called after a module has been detected to determine whether the module is supported for the upstream device.
module_remove
called after the module has been removed.
link_down
called when the link is non-operational for whatever reason.
link_up
called when the link is operational.
connect_phy
called when an I2C accessible PHY has been detected on the module.
disconnect_phy
called when a module with an I2C accessible PHY has been removed.
int sfp_parse_port(struct sfp_bus * bus, const struct sfp_eeprom_id * id, unsigned long * support)

Parse the EEPROM base ID, setting the port type

Parameters

struct sfp_bus * bus
a pointer to the struct sfp_bus structure for the sfp module
const struct sfp_eeprom_id * id
a pointer to the module’s struct sfp_eeprom_id
unsigned long * support
optional pointer to an array of unsigned long for the ethtool support mask

Description

Parse the EEPROM identification given in id, and return one of PORT_TP, PORT_FIBRE or PORT_OTHER. If support is non-NULL, also set the ethtool ETHTOOL_LINK_MODE_xxx_BIT corresponding with the connector type.

If the port type is not known, returns PORT_OTHER.

void sfp_parse_support(struct sfp_bus * bus, const struct sfp_eeprom_id * id, unsigned long * support)

Parse the eeprom id for supported link modes

Parameters

struct sfp_bus * bus
a pointer to the struct sfp_bus structure for the sfp module
const struct sfp_eeprom_id * id
a pointer to the module’s struct sfp_eeprom_id
unsigned long * support
pointer to an array of unsigned long for the ethtool support mask

Description

Parse the EEPROM identification information and derive the supported ethtool link modes for the module.

phy_interface_t sfp_select_interface(struct sfp_bus * bus, const struct sfp_eeprom_id * id, unsigned long * link_modes)

Select appropriate phy_interface_t mode

Parameters

struct sfp_bus * bus
a pointer to the struct sfp_bus structure for the sfp module
const struct sfp_eeprom_id * id
a pointer to the module’s struct sfp_eeprom_id
unsigned long * link_modes
ethtool link modes mask

Description

Derive the phy_interface_t mode for the information found in the module’s identifying EEPROM and the link modes mask. There is no standard or defined way to derive this information, so we decide based upon the link mode mask.

int sfp_get_module_info(struct sfp_bus * bus, struct ethtool_modinfo * modinfo)

Get the ethtool_modinfo for a SFP module

Parameters

struct sfp_bus * bus
a pointer to the struct sfp_bus structure for the sfp module
struct ethtool_modinfo * modinfo
a struct ethtool_modinfo

Description

Fill in the type and eeprom_len parameters in modinfo for a module on the sfp bus specified by bus.

Returns 0 on success or a negative errno number.

int sfp_get_module_eeprom(struct sfp_bus * bus, struct ethtool_eeprom * ee, u8 * data)

Read the SFP module EEPROM

Parameters

struct sfp_bus * bus
a pointer to the struct sfp_bus structure for the sfp module
struct ethtool_eeprom * ee
a struct ethtool_eeprom
u8 * data
buffer to contain the EEPROM data (must be at least ee->len bytes)

Description

Read the EEPROM as specified by the supplied ee. See the documentation for struct ethtool_eeprom for the region to be read.

Returns 0 on success or a negative errno number.

void sfp_upstream_start(struct sfp_bus * bus)

Inform the SFP that the network device is up

Parameters

struct sfp_bus * bus
a pointer to the struct sfp_bus structure for the sfp module

Description

Inform the SFP socket that the network device is now up, so that the module can be enabled by allowing TX_DISABLE to be deasserted. This should be called from the network device driver’s struct net_device_ops ndo_open() method.

void sfp_upstream_stop(struct sfp_bus * bus)

Inform the SFP that the network device is down

Parameters

struct sfp_bus * bus
a pointer to the struct sfp_bus structure for the sfp module

Description

Inform the SFP socket that the network device is now up, so that the module can be disabled by asserting TX_DISABLE, disabling the laser in optical modules. This should be called from the network device driver’s struct net_device_ops ndo_stop() method.

struct sfp_bus * sfp_register_upstream(struct fwnode_handle * fwnode, struct net_device * ndev, void * upstream, const struct sfp_upstream_ops * ops)

Register the neighbouring device

Parameters

struct fwnode_handle * fwnode
firmware node for the SFP bus
struct net_device * ndev
network device associated with the interface
void * upstream
the upstream private data
const struct sfp_upstream_ops * ops
the upstream’s struct sfp_upstream_ops

Description

Register the upstream device (eg, PHY) with the SFP bus. MAC drivers should use phylink, which will call this function for them. Returns a pointer to the allocated struct sfp_bus.

On error, returns NULL.

void sfp_unregister_upstream(struct sfp_bus * bus)

Unregister sfp bus

Parameters

struct sfp_bus * bus
a pointer to the struct sfp_bus structure for the sfp module

Description

Unregister a previously registered upstream connection for the SFP module. bus is returned from sfp_register_upstream().