Commit 7ebe183c authored by Yuchung Cheng's avatar Yuchung Cheng Committed by David S. Miller

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: default avatarYuchung Cheng <ycheng@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8fe7f99a
...@@ -2059,11 +2059,8 @@ void tcp_enter_loss(struct sock *sk, int how) ...@@ -2059,11 +2059,8 @@ void tcp_enter_loss(struct sock *sk, int how)
if (tcp_is_reno(tp)) if (tcp_is_reno(tp))
tcp_reset_reno_sack(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; tp->undo_marker = tp->snd_una;
} else { if (how) {
tp->sacked_out = 0; tp->sacked_out = 0;
tp->fackets_out = 0; tp->fackets_out = 0;
} }
......
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