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>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 19746b3..c507577 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1466,8 +1466,10 @@
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 @@
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)