This is a note to let you know that I've just added the patch titled
tcp: undo spurious timeout after SACK reneging
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tcp-undo-spurious-timeout-after-sack-reneging.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From de5b85d1ca7ac5b79f9274fe6c4a3ed5767feaf5 Mon Sep 17 00:00:00 2001
From: Yuchung Cheng <ycheng@xxxxxxxxxx>
Date: Sun, 24 Mar 2013 10:42:25 +0000
Subject: tcp: undo spurious timeout after SACK reneging
From: Yuchung Cheng <ycheng@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_input.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2260,11 +2260,8 @@ void tcp_enter_loss(struct sock *sk, int
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;
}
Patches currently in stable-queue which might be from ycheng@xxxxxxxxxx are
queue-3.4/tcp-preserve-ack-clocking-in-tso.patch
queue-3.4/tcp-undo-spurious-timeout-after-sack-reneging.patch
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