From d7fe54c17aa3995a62345946d6ff8ddc03c17d2a Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Tue, 8 Jan 2019 18:14:28 -0800 Subject: [PATCH] tcp: change txhash on SYN-data timeout [ Upstream commit c5715b8fabfca0ef85903f8bad2189940ed41cc8 ] Previously upon SYN timeouts the sender recomputes the txhash to try a different path. However this does not apply on the initial timeout of SYN-data (active Fast Open). Therefore an active IPv6 Fast Open connection may incur one second RTO penalty to take on a new path after the second SYN retransmission uses a new flow label. This patch removes this undesirable behavior so Fast Open changes the flow label just like the regular connections. This also helps avoid falsely disabling Fast Open on the sender which triggers after two consecutive SYN timeouts on Fast Open. Signed-off-by: Yuchung Cheng Reviewed-by: Neal Cardwell Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_timer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 57eae8d70ba1..b1b5a648def6 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -224,7 +224,7 @@ static int tcp_write_timeout(struct sock *sk) if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { if (icsk->icsk_retransmits) { dst_negative_advice(sk); - } else if (!tp->syn_data && !tp->syn_fastopen) { + } else { sk_rethink_txhash(sk); } retry_until = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_syn_retries; -- 2.17.1