This is a note to let you know that I've just added the patch titled
tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states
to the 4.9-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-avoid-setting-cwnd-to-invalid-ssthresh-after-cwnd-reduction-states.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Aug 11 09:10:20 PDT 2017
From: Yuchung Cheng <ycheng@xxxxxxxxxx>
Date: Tue, 1 Aug 2017 13:22:32 -0700
Subject: tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states
From: Yuchung Cheng <ycheng@xxxxxxxxxx>
[ Upstream commit ed254971edea92c3ac5c67c6a05247a92aa6075e ]
If the sender switches the congestion control during ECN-triggered
cwnd-reduction state (CA_CWR), upon exiting recovery cwnd is set to
the ssthresh value calculated by the previous congestion control. If
the previous congestion control is BBR that always keep ssthresh
to TCP_INIFINITE_SSTHRESH, cwnd ends up being infinite. The safe
step is to avoid assigning invalid ssthresh value when recovery ends.
Signed-off-by: Yuchung Cheng <ycheng@xxxxxxxxxx>
Signed-off-by: Neal Cardwell <ncardwell@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_input.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2560,8 +2560,8 @@ static inline void tcp_end_cwnd_reductio
return;
/* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */
- if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR ||
- (tp->undo_marker && tp->snd_ssthresh < TCP_INFINITE_SSTHRESH)) {
+ if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH &&
+ (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR || tp->undo_marker)) {
tp->snd_cwnd = tp->snd_ssthresh;
tp->snd_cwnd_stamp = tcp_time_stamp;
}
Patches currently in stable-queue which might be from ycheng@xxxxxxxxxx are
queue-4.9/tcp-avoid-setting-cwnd-to-invalid-ssthresh-after-cwnd-reduction-states.patch
queue-4.9/tcp-fastopen-tcp_connect-must-refresh-the-route.patch
queue-4.9/net-fix-keepalive-code-vs-tcp_fastopen_connect.patch