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authorYuchung Cheng <ycheng@google.com>2013-03-24 10:42:25 +0000
committerDavid S. Miller <davem@davemloft.net>2013-03-24 17:27:28 -0400
commit7ebe183c6d444ef5587d803b64a1f4734b18c564 (patch)
tree8e49b71e1d0ffc90ce725830b7bb6d2363495b70
parent8fe7f99a9e11a43183bc27420309ae105e1fec1a (diff)
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>
-rw-r--r--net/ipv4/tcp_input.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0d9bdacce99..3bd55bad230 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;
}