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| author | Eric Dumazet <edumazet@google.com> | 2013-02-03 09:13:05 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-02-14 10:49:06 -0800 |
| commit | 2813296332187d222b96363fe29f10929f7a5228 (patch) | |
| tree | 10dfdbd0714285dbb4385bfd38f67ae968b6a4aa | |
| parent | 42671f1e6fd8922b071bd3fd3e0cfad7226c654d (diff) | |
| download | lwn-2813296332187d222b96363fe29f10929f7a5228.tar.gz lwn-2813296332187d222b96363fe29f10929f7a5228.zip | |
tcp: frto should not set snd_cwnd to 0
[ 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 Kärkkäinen <pasik@iki.fi>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/ipv4/tcp_input.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 0e0b6d0e9a61..d8c308f74d58 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3619,7 +3619,8 @@ static int tcp_process_frto(struct sock *sk, int flag) ((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; } |