Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9d691539 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: do not enqueue skb with SYN flag 



If we remove the SYN flag from the skbs that tcp_fastopen_add_skb()
places in socket receive queue, then we can remove the test that
tcp_recvmsg() has to perform in fast path.

All we have to do is to adjust SEQ in the slow path.

For the moment, we place an unlikely() and output a message
if we find an skb having SYN flag set.
Goal would be to get rid of the test completely.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 61d2bcae

net/ipv4/tcp.c

+6 −2
Original line number Diff line number Diff line
@@ -1466,8 +1466,10 @@ static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off) 


	while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {

		offset = seq - TCP_SKB_CB(skb)->seq;

		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)

		if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {

			pr_err_once("%s: found a SYN, please report !\n", __func__);

			offset--;

		}

		if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) {

			*off = offset;

			return skb;
@@ -1657,8 +1659,10 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 
				break;



			offset = *seq - TCP_SKB_CB(skb)->seq;

			if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)

			if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {

				pr_err_once("%s: found a SYN, please report !\n", __func__);

				offset--;

			}

			if (offset < skb->len)

				goto found_ok_skb;

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

net/ipv4/tcp_fastopen.c

+3 −0
Original line number Diff line number Diff line
@@ -143,6 +143,9 @@ void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb) 
	__skb_pull(skb, tcp_hdrlen(skb));

	skb_set_owner_r(skb, sk);



	TCP_SKB_CB(skb)->seq++;

	TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_SYN;



	tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;

	__skb_queue_tail(&sk->sk_receive_queue, skb);

	tp->syn_data_acked = 1;