Network layer representation of sockets
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_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
socket_lock_t sk_lock;
struct sk_buff_head sk_receive_queue;
struct sk_backlog;
#define sk_rmem_alloc sk_backlog.rmem_alloc
int sk_forward_alloc;
#ifdef CONFIG_RPS
__u32 sk_rxhash;
#endif
#ifdef CONFIG_NET_RX_BUSY_POLL
unsigned int sk_napi_id;
unsigned int sk_ll_usec;
#endif
atomic_t sk_drops;
int sk_rcvbuf;
struct sk_filter __rcu * sk_filter;
struct socket_wq __rcu * sk_wq;
#ifdef CONFIG_NET_DMA
struct sk_buff_head sk_async_wait_queue;
#endif
#ifdef CONFIG_XFRM
struct xfrm_policy * sk_policy[2];
#endif
unsigned long sk_flags;
struct dst_entry * sk_rx_dst;
struct dst_entry __rcu * sk_dst_cache;
spinlock_t sk_dst_lock;
atomic_t sk_wmem_alloc;
atomic_t sk_omem_alloc;
int sk_sndbuf;
struct sk_buff_head sk_write_queue;
unsigned int sk_shutdown: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
int sk_wmem_queued;
gfp_t sk_allocation;
u32 sk_pacing_rate;
u32 sk_max_pacing_rate;
netdev_features_t sk_route_caps;
netdev_features_t sk_route_nocaps;
int sk_gso_type;
unsigned int sk_gso_max_size;
u16 sk_gso_max_segs;
int sk_rcvlowat;
unsigned long sk_lingertime;
struct sk_buff_head sk_error_queue;
struct proto * sk_prot_creator;
rwlock_t sk_callback_lock;
int sk_err;
int sk_err_soft;
unsigned short sk_ack_backlog;
unsigned short sk_max_ack_backlog;
__u32 sk_priority;
#if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
__u32 sk_cgrp_prioidx;
#endif
struct pid * sk_peer_pid;
const struct cred * sk_peer_cred;
long sk_rcvtimeo;
long sk_sndtimeo;
void * sk_protinfo;
struct timer_list sk_timer;
ktime_t sk_stamp;
struct socket * sk_socket;
void * sk_user_data;
struct page_frag sk_frag;
struct sk_buff * sk_send_head;
__s32 sk_peek_off;
int sk_write_pending;
#ifdef CONFIG_SECURITY
void * sk_security;
#endif
__u32 sk_mark;
u32 sk_classid;
struct cg_proto * sk_cgrp;
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);
};
__sk_common
shared layout with inet_timewait_sock
sk_lock
synchronizer
sk_receive_queue
incoming packets
sk_backlog
always used with the per-socket spinlock held
sk_forward_alloc
space allocated forward
sk_rxhash
flow hash received from netif layer
sk_napi_id
id of the last napi context to receive data for sk
sk_ll_usec
usecs to busypoll when there is no data
sk_drops
raw/udp drops counter
sk_rcvbuf
size of receive buffer in bytes
sk_filter
socket filtering instructions
sk_wq
sock wait queue and async head
sk_async_wait_queue
DMA copied packets
sk_policy[2]
flow policy
sk_flags
SO_LINGER (l_onoff), SO_BROADCAST, SO_KEEPALIVE, SO_OOBINLINE settings, SO_TIMESTAMPING settings
sk_rx_dst
receive input route used by early demux
sk_dst_cache
destination cache
sk_dst_lock
destination cache lock
sk_wmem_alloc
transmit queue bytes committed
sk_omem_alloc
"o“ is ”option“ or ”other"
sk_sndbuf
size of send buffer in bytes
sk_write_queue
Packet sending queue
sk_shutdown
mask of SEND_SHUTDOWN and/or RCV_SHUTDOWN
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_wmem_queued
persistent queue size
sk_allocation
allocation mode
sk_pacing_rate
Pacing rate (if supported by transport/packet scheduler)
sk_max_pacing_rate
Maximum pacing rate (SO_MAX_PACING_RATE)
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_gso_max_segs
Maximum number of GSO segments
sk_rcvlowat
SO_RCVLOWAT setting
sk_lingertime
SO_LINGER l_linger setting
sk_error_queue
rarely used
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_priority
SO_PRIORITY setting
sk_cgrp_prioidx
socket group's priority map index
sk_peer_pid
struct pid for this socket's peer
sk_peer_cred
SO_PEERCRED setting
sk_rcvtimeo
SO_RCVTIMEO setting
sk_sndtimeo
SO_SNDTIMEO setting
sk_protinfo
private area, net family specific, when not using slab
sk_timer
sock cleanup timer
sk_stamp
time stamp of last packet received
sk_socket
Identd and reporting IO signals
sk_user_data
RPC layer private data
sk_frag
cached page frag
sk_send_head
front of stuff to transmit
sk_peek_off
current peek_offset value
sk_write_pending
a write to stream socket waits to start
sk_security
used by security modules
sk_mark
generic packet mark
sk_classid
this socket's cgroup classid
sk_cgrp
this socket's cgroup-specific proto data
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