This is a note to let you know that I've just added the patch titled
tcp: reset timer after any SYNACK retransmit
to the 3.9-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-reset-timer-after-any-synack-retransmit.patch
and it can be found in the queue-3.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3dde7861ebc8d13c1bff35bf82f86df8f03674f0 Mon Sep 17 00:00:00 2001
From: Yuchung Cheng <ycheng@xxxxxxxxxx>
Date: Mon, 29 Apr 2013 08:44:51 +0000
Subject: tcp: reset timer after any SYNACK retransmit
From: Yuchung Cheng <ycheng@xxxxxxxxxx>
[ Upstream commit cd75eff64dae8856afbf6ef0f0ca3c145465d8e0 ]
Linux immediately returns SYNACK on (spurious) SYN retransmits, but
keeps the SYNACK timer running independently. Thus the timer may
fire right after the SYNACK retransmit and causes a SYN-SYNACK
cross-fire burst.
Adopt the fast retransmit/recovery idea in established state by
re-arming the SYNACK timer after the fast (SYNACK) retransmit. The
timer may fire late up to 500ms due to the current SYNACK timer wheel,
but it's OK to be conservative when network is congested. Eric's new
listener design should address this issue.
Signed-off-by: Yuchung Cheng <ycheng@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@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_minisocks.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -583,8 +583,13 @@ struct sock *tcp_check_req(struct sock *
*
* Note that even if there is new data in the SYN packet
* they will be thrown away too.
+ *
+ * Reset timer after retransmitting SYNACK, similar to
+ * the idea of fast retransmit in recovery.
*/
- inet_rtx_syn_ack(sk, req);
+ if (!inet_rtx_syn_ack(sk, req))
+ req->expires = min(TCP_TIMEOUT_INIT << req->num_timeout,
+ TCP_RTO_MAX) + jiffies;
return NULL;
}
Patches currently in stable-queue which might be from ycheng@xxxxxxxxxx are
queue-3.9/tcp-reset-timer-after-any-synack-retransmit.patch
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