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: Eric Dumazet <edumazet@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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61d2bcae99
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9d691539ee
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@ -1466,8 +1466,10 @@ static struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off)
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while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
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offset = seq - TCP_SKB_CB(skb)->seq;
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if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
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if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
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pr_err_once("%s: found a SYN, please report !\n", __func__);
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offset--;
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}
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if (offset < skb->len || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) {
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*off = offset;
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return skb;
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@ -1657,8 +1659,10 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
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break;
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offset = *seq - TCP_SKB_CB(skb)->seq;
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if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
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if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
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pr_err_once("%s: found a SYN, please report !\n", __func__);
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offset--;
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}
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if (offset < skb->len)
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goto found_ok_skb;
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if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
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@ -143,6 +143,9 @@ void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb)
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__skb_pull(skb, tcp_hdrlen(skb));
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skb_set_owner_r(skb, sk);
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TCP_SKB_CB(skb)->seq++;
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_SYN;
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tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
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__skb_queue_tail(&sk->sk_receive_queue, skb);
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tp->syn_data_acked = 1;
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