STRUCT SOCK(9)

NAME
struct_sock - network layer representation of sockets

SYNOPSIS

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
#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 {unnamed_struct};
#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;
  atomic_t sk_wmem_alloc;
  struct sk_buff * sk_send_head;
  struct sk_buff_head sk_write_queue;
  __s32 sk_peek_off;
  int sk_write_pending;
  long sk_sndtimeo;
  struct timer_list sk_timer;
  __u32 sk_priority;
  __u32 sk_mark;
  u32 sk_pacing_rate;
  u32 sk_max_pacing_rate;
  struct page_frag sk_frag;
  netdev_features_t sk_route_caps;
  netdev_features_t sk_route_nocaps;
  int sk_gso_type;
  unsigned int sk_gso_max_size;
  gfp_t sk_allocation;
  __u32 sk_txhash;
#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:2;
  unsigned int sk_no_check_tx:1;
  unsigned int sk_no_check_rx:1;
  unsigned int sk_userlocks:4;
  unsigned int sk_protocol:8;
  unsigned int sk_type:16;
#define SK_PROTOCOL_MAX U8_MAX
  u16 sk_gso_max_segs;
  unsigned long sk_lingertime;
  struct proto * sk_prot_creator;
  rwlock_t sk_callback_lock;
  int sk_err;
  int sk_err_soft;
  u32 sk_ack_backlog;
  u32 sk_max_ack_backlog;
  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;
  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);
  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

{unnamed_struct}
    anonymous

sk_policy[2]
    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_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_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_padding
    unused element for alignment

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_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_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_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

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