This is a note to let you know that I've just added the patch titled
tcp: fix infinite cwnd in tcp_complete_cwr()
to the 3.3-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-fix-infinite-cwnd-in-tcp_complete_cwr.patch
and it can be found in the queue-3.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 9f7cf25f200a16301c97045fdf028ce6b27000e2 Mon Sep 17 00:00:00 2001
From: Yuchung Cheng <[email protected]>
Date: Mon, 30 Apr 2012 06:00:18 +0000
Subject: tcp: fix infinite cwnd in tcp_complete_cwr()
From: Yuchung Cheng <[email protected]>
[ Upstream commit 1cebce36d660c83bd1353e41f3e66abd4686f215 ]
When the cwnd reduction is done, ssthresh may be infinite
if TCP enters CWR via ECN or F-RTO. If cwnd is not undone, i.e.,
undo_marker is set, tcp_complete_cwr() falsely set cwnd to the
infinite ssthresh value. The correct operation is to keep cwnd
intact because it has been updated in ECN or F-RTO.
Signed-off-by: Yuchung Cheng <[email protected]>
Acked-by: Neal Cardwell <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/ipv4/tcp_input.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2866,11 +2866,14 @@ static inline void tcp_complete_cwr(stru
/* Do not moderate cwnd if it's already undone in cwr or recovery. */
if (tp->undo_marker) {
- if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR)
+ if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR) {
tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
- else /* PRR */
+ tp->snd_cwnd_stamp = tcp_time_stamp;
+ } else if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH) {
+ /* PRR algorithm. */
tp->snd_cwnd = tp->snd_ssthresh;
- tp->snd_cwnd_stamp = tcp_time_stamp;
+ tp->snd_cwnd_stamp = tcp_time_stamp;
+ }
}
tcp_ca_event(sk, CA_EVENT_COMPLETE_CWR);
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.3/tcp-fix-infinite-cwnd-in-tcp_complete_cwr.patch
queue-3.3/tcp-change-tcp_adv_win_scale-and-tcp_rmem.patch
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