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authorYuchung Cheng <ycheng@google.com>2013-03-24 10:42:25 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-04-05 10:16:53 -0700
commit01326198867ce1ab1bb26acb48de7b06eab571fe (patch)
treec5ec9099cf5b75c2dbd7331a1bbf4e79392b89bd
parent06551316b51c5f140c29748011c37057cb7ba932 (diff)
downloadlinux-linaro-stable-01326198867ce1ab1bb26acb48de7b06eab571fe.tar.gz
tcp: undo spurious timeout after SACK reneging
[ Upstream commit 7ebe183c6d444ef5587d803b64a1f4734b18c564 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 8a56d24dcb94..ab44f9d6dde7 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2244,11 +2244,8 @@ 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;
}