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 <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng 2013-03-24 10:42:25 +00:00 committed by David S. Miller
parent 8fe7f99a9e
commit 7ebe183c6d

View file

@ -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;
}