Commit 04919bed authored by Cong Wang's avatar Cong Wang Committed by Daniel Borkmann
Browse files

tcp: Introduce tcp_read_skb() 



This patch inroduces tcp_read_skb() based on tcp_read_sock(),
a preparation for the next patch which actually introduces
a new sock ops.

TCP is special here, because it has tcp_read_sock() which is
mainly used by splice(). tcp_read_sock() supports partial read
and arbitrary offset, neither of them is needed for sockmap.

Signed-off-by: default avatarCong Wang <cong.wang@bytedance.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220615162014.89193-2-xiyou.wangcong@gmail.com
parent 4336487e

include/net/tcp.h

+2 −0
Original line number Diff line number Diff line
@@ -672,6 +672,8 @@ void tcp_get_info(struct sock *, struct tcp_info *); 
/* Read 'sendfile()'-style from a TCP socket */

int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,

		  sk_read_actor_t recv_actor);

int tcp_read_skb(struct sock *sk, read_descriptor_t *desc,

		 sk_read_actor_t recv_actor);



void tcp_initialize_rcv_mss(struct sock *sk);

net/ipv4/tcp.c

+47 −0
Original line number Diff line number Diff line
@@ -1734,6 +1734,53 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 
}

EXPORT_SYMBOL(tcp_read_sock);



int tcp_read_skb(struct sock *sk, read_descriptor_t *desc,

		 sk_read_actor_t recv_actor)

{

	struct tcp_sock *tp = tcp_sk(sk);

	u32 seq = tp->copied_seq;

	struct sk_buff *skb;

	int copied = 0;

	u32 offset;



	if (sk->sk_state == TCP_LISTEN)

		return -ENOTCONN;



	while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {

		int used;



		__skb_unlink(skb, &sk->sk_receive_queue);

		used = recv_actor(desc, skb, 0, skb->len);

		if (used <= 0) {

			if (!copied)

				copied = used;

			break;

		}

		seq += used;

		copied += used;



		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {

			consume_skb(skb);

			++seq;

			break;

		}

		consume_skb(skb);

		if (!desc->count)

			break;

		WRITE_ONCE(tp->copied_seq, seq);

	}

	WRITE_ONCE(tp->copied_seq, seq);



	tcp_rcv_space_adjust(sk);



	/* Clean up data we have read: This will do ACK frames. */

	if (copied > 0)

		tcp_cleanup_rbuf(sk, copied);



	return copied;

}

EXPORT_SYMBOL(tcp_read_skb);



int tcp_peek_len(struct socket *sock)

{

	return tcp_inq(sock->sk);