Commit 6731d209 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller

tcp: fix for zero packets_in_flight was too broad

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: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Tested-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b6ec447d
...@@ -3484,8 +3484,7 @@ static bool tcp_process_frto(struct sock *sk, int flag) ...@@ -3484,8 +3484,7 @@ static bool tcp_process_frto(struct sock *sk, int flag)
((tp->frto_counter >= 2) && (flag & FLAG_RETRANS_DATA_ACKED))) ((tp->frto_counter >= 2) && (flag & FLAG_RETRANS_DATA_ACKED)))
tp->undo_marker = 0; 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); tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3), flag);
return true; return true;
} }
...@@ -3505,6 +3504,11 @@ static bool tcp_process_frto(struct sock *sk, int flag) ...@@ -3505,6 +3504,11 @@ static bool tcp_process_frto(struct sock *sk, int flag)
} }
} else { } else {
if (!(flag & FLAG_DATA_ACKED) && (tp->frto_counter == 1)) { 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. */ /* Prevent sending of new data. */
tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_cwnd = min(tp->snd_cwnd,
tcp_packets_in_flight(tp)); tcp_packets_in_flight(tp));
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment