From 6731d2095bd4aef18027c72ef845ab1087c3ba63 Mon Sep 17 00:00:00 2001 From: Ilpo Järvinen Date: Mon, 4 Feb 2013 02:14:25 +0000 Subject: tcp: fix for zero packets_in_flight was too broad MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There are transients during normal FRTO procedure during which the packets_in_flight can go to zero between write_queue state updates and firing the resulting segments out. As FRTO processing occurs during that window the check must be more precise to not match "spuriously" :-). More specificly, e.g., when packets_in_flight is zero but FLAG_DATA_ACKED is true the problematic branch that set cwnd into zero would not be taken and new segments might be sent out later. Signed-off-by: Ilpo Järvinen Tested-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 680c4224ed96..ad70a962c20e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3484,8 +3484,7 @@ 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) || - !tcp_packets_in_flight(tp)) { + if (!before(tp->snd_una, tp->frto_highmark)) { tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3), flag); return true; } @@ -3505,6 +3504,11 @@ static bool tcp_process_frto(struct sock *sk, int flag) } } else { if (!(flag & FLAG_DATA_ACKED) && (tp->frto_counter == 1)) { + if (!tcp_packets_in_flight(tp)) { + tcp_enter_frto_loss(sk, 2, flag); + return true; + } + /* Prevent sending of new data. */ tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp)); -- cgit v1.2.3