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Message-Id: <20130212203416.776145370@linuxfoundation.org>
Date: Tue, 12 Feb 2013 12:37:00 -0800
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Pasi K�rkk�inen <pasik@....fi>,
Neal Cardwell <ncardwell@...gle.com>,
Eric Dumazet <edumazet@...gle.com>,
Ilpo J�rvinen <ilpo.jarvinen@...sinki.fi>,
Yuchung Cheng <ycheng@...gle.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [ 17/22] tcp: frto should not set snd_cwnd to 0
3.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@...gle.com>
[ Upstream commit 2e5f421211ff76c17130b4597bc06df4eeead24f ]
Commit 9dc274151a548 (tcp: fix ABC in tcp_slow_start())
uncovered a bug in FRTO code :
tcp_process_frto() is setting snd_cwnd to 0 if the number
of in flight packets is 0.
As Neal pointed out, if no packet is in flight we lost our
chance to disambiguate whether a loss timeout was spurious.
We should assume it was a proper loss.
Reported-by: Pasi K�rkk�inen <pasik@....fi>
Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Ilpo J�rvinen <ilpo.jarvinen@...sinki.fi>
Cc: Yuchung Cheng <ycheng@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/ipv4/tcp_input.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3568,7 +3568,8 @@ static int tcp_process_frto(struct sock
((tp->frto_counter >= 2) && (flag & FLAG_RETRANS_DATA_ACKED)))
tp->undo_marker = 0;
- if (!before(tp->snd_una, tp->frto_highmark)) {
+ if (!before(tp->snd_una, tp->frto_highmark) ||
+ !tcp_packets_in_flight(tp)) {
tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3), flag);
return 1;
}
--
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