net/core/skmsg.c

File Facts

System

Linux kernel

Corpus path

net/core/skmsg.c

Extension

.c

Size

31076 bytes

Lines

1278

Domain

Networking Core

Bucket

Sockets, Protocols, Packet Path, And Network Policy

Inferred role

Networking Core: operation-table or driver-model contract

Status

pattern implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

• Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.
• Defines an operation table; this is where Linux turns generic core objects into subsystem-specific behavior.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Allocates kernel memory; connect allocation flags and lifetime to context constraints.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/skmsg.h
• linux/skbuff.h
• linux/scatterlist.h
• net/sock.h
• net/tcp.h
• trace/events/sock.h

Detected Declarations

• function sk_msg_try_coalesce_ok
• function sk_msg_alloc
• function sk_msg_clone
• function sk_msg_return_zero
• function sk_msg_return
• function sk_msg_free_elem
• function __sk_msg_free
• function sk_msg_free_nocharge
• function sk_msg_free
• function __sk_msg_free_partial
• function sk_msg_free_partial
• function sk_msg_free_partial_nocharge
• function sk_msg_trim
• function sk_msg_iter_dist
• function sk_msg_zerocopy_from_iter
• function sk_msg_memcopy_from_iter
• function __sk_msg_recvmsg
• function sk_msg_recvmsg
• function sk_msg_is_readable
• function sk_psock_skb_ingress_enqueue
• function sk_psock_skb_ingress
• function sk_psock_skb_ingress_self
• function sk_psock_handle_skb
• function sk_psock_skb_state
• function sk_psock_backlog
• function __sk_psock_purge_ingress_msg
• function list_for_each_entry_safe
• function __sk_psock_zap_ingress
• function sk_psock_link_destroy
• function list_for_each_entry_safe
• function sk_psock_stop
• function sk_psock_destroy
• function sk_psock_drop
• function sk_psock_map_verd
• function sk_psock_msg_verdict
• function sk_psock_skb_redirect
• function sk_psock_verdict_apply
• function sk_psock_write_space
• function sk_psock_strp_read
• function sk_psock_strp_read_done
• function sk_psock_strp_parse
• function sk_psock_strp_data_ready
• function sk_psock_init_strp
• function sk_psock_start_strp
• function sk_psock_stop_strp
• function sk_psock_done_strp
• function sk_psock_done_strp
• function sk_psock_verdict_data_ready

Annotated Snippet

const struct proto_ops *ops = NULL;
	struct sk_psock *psock;
	struct socket *sock;
	int copied;

	trace_sk_data_ready(sk);

	rcu_read_lock();
	sock = READ_ONCE(sk->sk_socket);
	if (likely(sock))
		ops = READ_ONCE(sock->ops);
	rcu_read_unlock();
	if (!ops || !ops->read_skb)
		return;

	copied = ops->read_skb(sk, sk_psock_verdict_recv);
	if (copied >= 0) {
		rcu_read_lock();
		psock = sk_psock(sk);
		if (psock)
			sk_psock_data_ready(sk, psock);
		rcu_read_unlock();
	}
}

void sk_psock_start_verdict(struct sock *sk, struct sk_psock *psock)
{
	if (psock->saved_data_ready)
		return;

	psock->saved_data_ready = sk->sk_data_ready;
	WRITE_ONCE(sk->sk_data_ready, sk_psock_verdict_data_ready);
	WRITE_ONCE(sk->sk_write_space, sk_psock_write_space);
}

void sk_psock_stop_verdict(struct sock *sk, struct sk_psock *psock)
{
	psock_set_prog(&psock->progs.stream_verdict, NULL);
	psock_set_prog(&psock->progs.skb_verdict, NULL);

	if (!psock->saved_data_ready)
		return;

	WRITE_ONCE(sk->sk_data_ready, psock->saved_data_ready);
	psock->saved_data_ready = NULL;
}

Annotation

• Immediate include surface: `linux/skmsg.h`, `linux/skbuff.h`, `linux/scatterlist.h`, `net/sock.h`, `net/tcp.h`, `trace/events/sock.h`.
• Detected declarations: `function sk_msg_try_coalesce_ok`, `function sk_msg_alloc`, `function sk_msg_clone`, `function sk_msg_return_zero`, `function sk_msg_return`, `function sk_msg_free_elem`, `function __sk_msg_free`, `function sk_msg_free_nocharge`, `function sk_msg_free`, `function __sk_msg_free_partial`.
• Atlas domain: Networking Core / Sockets, Protocols, Packet Path, And Network Policy.
• Implementation status: pattern implementation candidate.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.