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From: Eric Dumazet <eric.dumazet@gmail.com>
To: "Pasi Kärkkäinen" <pasik@iki.fi>, "David Miller" <davem@davemloft.net>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>,
	Stephen Hemminger <stephen@networkplumber.org>,
	netdev@vger.kernel.org, Neal Cardwell <ncardwell@google.com>,
	Yuchung Cheng <ycheng@google.com>
Subject: [PATCH] tcp: tcp_process_frto() should not set snd_cwnd to 0
Date: Sat, 02 Feb 2013 07:14:35 -0800	[thread overview]
Message-ID: <1359818075.30177.78.camel@edumazet-glaptop> (raw)
In-Reply-To: <20130202142832.GP8912@reaktio.net>

From: Eric Dumazet <edumazet@google.com>

snd_cwnd minimal value is 1, not 0, or tcp_slow_start()
is broken : infinite loop since commit 9dc274151a548
(tcp: fix ABC in tcp_slow_start())

A separate patch will make tcp_slow_start() more robust.

Reported-by: Pasi Kärkkäinen <pasik@iki.fi>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
---
 net/ipv4/tcp_input.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 8aca4ee..37760df 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3506,7 +3506,7 @@ static bool tcp_process_frto(struct sock *sk, int flag)
 		if (!(flag & FLAG_DATA_ACKED) && (tp->frto_counter == 1)) {
 			/* Prevent sending of new data. */
 			tp->snd_cwnd = min(tp->snd_cwnd,
-					   tcp_packets_in_flight(tp));
+					   max(tcp_packets_in_flight(tp), 1U));
 			return true;
 		}
 

  reply	other threads:[~2013-02-02 15:14 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-23 16:12 Linux 3.6.x kernel crash in tcp_slow_start / bictcp_cong_avoid with wfica Pasi Kärkkäinen
2013-01-23 21:44 ` Hannes Frederic Sowa
2013-01-23 21:51   ` Pasi Kärkkäinen
2013-01-23 22:00     ` Hannes Frederic Sowa
2013-01-24  7:14       ` Pasi Kärkkäinen
2013-01-23 22:25     ` Eric Dumazet
2013-01-23 23:26     ` Stephen Hemminger
2013-01-23 23:41       ` Hannes Frederic Sowa
2013-01-23 23:47         ` Eric Dumazet
2013-01-24  6:59           ` Pasi Kärkkäinen
2013-01-24 13:51           ` Hannes Frederic Sowa
2013-02-02  3:51             ` Eric Dumazet
2013-02-02 14:28               ` Pasi Kärkkäinen
2013-02-02 15:14                 ` Eric Dumazet [this message]
2013-02-02 15:57                   ` [PATCH] tcp: tcp_process_frto() should not set snd_cwnd to 0 Neal Cardwell
2013-02-02 17:32                     ` Eric Dumazet
2013-02-03 19:13                       ` [PATCH] tcp: frto " Eric Dumazet
2013-02-03 21:01                         ` David Miller
2013-02-04 12:14                         ` Ilpo Järvinen
2013-02-04 15:07                           ` Eric Dumazet
2013-02-05 19:44                             ` Eric Dumazet
2013-02-05 19:49                           ` Neal Cardwell
2013-02-06 20:55                             ` David Miller
2013-02-06 21:13                               ` Pasi Kärkkäinen
2013-02-06 21:19                                 ` David Miller
2013-02-06 21:21                                   ` Pasi Kärkkäinen
2013-02-02 15:23                 ` [PATCH] tcp: fix an infinite loop in tcp_slow_start() Eric Dumazet
2013-02-03 21:01                   ` David Miller

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