From 7ebe183c6d444ef5587d803b64a1f4734b18c564 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Sun, 24 Mar 2013 10:42:25 +0000 Subject: [PATCH] tcp: undo spurious timeout after SACK reneging On SACK reneging the sender immediately retransmits and forces a timeout but disables Eifel (undo). If the (buggy) receiver does not drop any packet this can trigger a false slow-start retransmit storm driven by the ACKs of the original packets. This can be detected with undo and TCP timestamps. Signed-off-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 0d9bdacce99f..3bd55bad230a 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2059,11 +2059,8 @@ void tcp_enter_loss(struct sock *sk, int how) if (tcp_is_reno(tp)) tcp_reset_reno_sack(tp); - if (!how) { - /* Push undo marker, if it was plain RTO and nothing - * was retransmitted. */ - tp->undo_marker = tp->snd_una; - } else { + tp->undo_marker = tp->snd_una; + if (how) { tp->sacked_out = 0; tp->fackets_out = 0; } -- 2.20.1