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authorEric Dumazet <edumazet@google.com>2013-02-03 13:13:05 +0400
committerDavid S. Miller <davem@davemloft.net>2013-02-04 01:00:25 +0400
commit2e5f421211ff76c17130b4597bc06df4eeead24f (patch)
treefb24e2b58579db31a1ac6def65da1daeb89813e4 /net
parent973ec449bb4f2b8c514bacbcb4d9506fc31c8ce3 (diff)
downloadlinux-2e5f421211ff76c17130b4597bc06df4eeead24f.tar.xz
tcp: frto should not set snd_cwnd to 0
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>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_input.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 8aca4ee95ff9..680c4224ed96 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3484,7 +3484,8 @@ static bool 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 true;
}