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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: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220615162014.89193-2-xiyou.wangcong@gmail.com
This commit is contained in:
Cong Wang 2022-06-15 09:20:11 -07:00 committed by Daniel Borkmann
parent 4336487e30
commit 04919bed94
2 changed files with 49 additions and 0 deletions
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2
include/net/tcp.h
View File

@ -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);

47
net/ipv4/tcp.c
View File

@ -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);