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tcp: read multiple skbs in tcp_read_skb()

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Before we switched to ->read_skb(), ->read_sock() was passed with
desc.count=1, which technically indicates we only read one skb per
->sk_data_ready() call. However, for TCP, this is not true.

TCP at least has sk_rcvlowat which intentionally holds skb's in
receive queue until this watermark is reached. This means when
->sk_data_ready() is invoked there could be multiple skb's in the
queue, therefore we have to read multiple skbs in tcp_read_skb()
instead of one.

Fixes: 965b57b469 ("net: Introduce a new proto_ops ->read_skb()")
Reported-by: Peilin Ye <peilin.ye@bytedance.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Link: https://lore.kernel.org/r/20220912173553.235838-1-xiyou.wangcong@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Cong Wang 2022-09-12 10:35:53 -07:00 committed by Paolo Abeni
parent 90fdd1c1e9
commit db4192a754
1 changed files with 19 additions and 10 deletions
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29
net/ipv4/tcp.c
View File

@ -1761,19 +1761,28 @@ int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
if (sk->sk_state == TCP_LISTEN)
return -ENOTCONN;
skb = tcp_recv_skb(sk, seq, &offset);
if (!skb)
return 0;
while ((skb = tcp_recv_skb(sk, seq, &offset)) != NULL) {
u8 tcp_flags;
int used;
__skb_unlink(skb, &sk->sk_receive_queue);
WARN_ON_ONCE(!skb_set_owner_sk_safe(skb, sk));
copied = recv_actor(sk, skb);
if (copied >= 0) {
seq += copied;
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
__skb_unlink(skb, &sk->sk_receive_queue);
WARN_ON_ONCE(!skb_set_owner_sk_safe(skb, sk));
tcp_flags = TCP_SKB_CB(skb)->tcp_flags;
used = recv_actor(sk, skb);
consume_skb(skb);
if (used < 0) {
if (!copied)
copied = used;
break;
}
seq += used;
copied += used;
if (tcp_flags & TCPHDR_FIN) {
++seq;
break;
}
}
consume_skb(skb);
WRITE_ONCE(tp->copied_seq, seq);
tcp_rcv_space_adjust(sk);