| Message ID | 1335801618-31498-1-git-send-email-ycheng@google.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Mon, Apr 30, 2012 at 12:00 PM, Yuchung Cheng <ycheng@google.com> wrote: > When the cwnd reduction is done, ssthresh may be infinite > if TCP enters CWR via ECN or F-RTO. If cwnd is not undone, i.e., > undo_marker is set, tcp_complete_cwr() falsely set cwnd to the > infinite ssthresh value. The correct operation is to keep cwnd > intact because it has been updated in ECN or F-RTO. > > Signed-off-by: Yuchung Cheng <ycheng@google.com> > --- > ChangeLog since v1: > - Add snd_cwnd_stamp timestamping in CWR mode > > net/ipv4/tcp_input.c | 9 ++++++--- > 1 files changed, 6 insertions(+), 3 deletions(-) Acked-by: Neal Cardwell <ncardwell@google.com> neal -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Neal Cardwell <ncardwell@google.com> Date: Mon, 30 Apr 2012 12:25:56 -0400 > On Mon, Apr 30, 2012 at 12:00 PM, Yuchung Cheng <ycheng@google.com> wrote: >> When the cwnd reduction is done, ssthresh may be infinite >> if TCP enters CWR via ECN or F-RTO. If cwnd is not undone, i.e., >> undo_marker is set, tcp_complete_cwr() falsely set cwnd to the >> infinite ssthresh value. The correct operation is to keep cwnd >> intact because it has been updated in ECN or F-RTO. >> >> Signed-off-by: Yuchung Cheng <ycheng@google.com> >> --- >> ChangeLog since v1: >> - Add snd_cwnd_stamp timestamping in CWR mode >> >> net/ipv4/tcp_input.c | 9 ++++++--- >> 1 files changed, 6 insertions(+), 3 deletions(-) > > Acked-by: Neal Cardwell <ncardwell@google.com> Applied and queued up for -stable, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index c93b0cb..e0a9b89 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2868,11 +2868,14 @@ static inline void tcp_complete_cwr(struct sock *sk) /* Do not moderate cwnd if it's already undone in cwr or recovery. */ if (tp->undo_marker) { - if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR) + if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR) { tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh); - else /* PRR */ + tp->snd_cwnd_stamp = tcp_time_stamp; + } else if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH) { + /* PRR algorithm. */ tp->snd_cwnd = tp->snd_ssthresh; - tp->snd_cwnd_stamp = tcp_time_stamp; + tp->snd_cwnd_stamp = tcp_time_stamp; + } } tcp_ca_event(sk, CA_EVENT_COMPLETE_CWR); }
When the cwnd reduction is done, ssthresh may be infinite if TCP enters CWR via ECN or F-RTO. If cwnd is not undone, i.e., undo_marker is set, tcp_complete_cwr() falsely set cwnd to the infinite ssthresh value. The correct operation is to keep cwnd intact because it has been updated in ECN or F-RTO. Signed-off-by: Yuchung Cheng <ycheng@google.com> --- ChangeLog since v1: - Add snd_cwnd_stamp timestamping in CWR mode net/ipv4/tcp_input.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-)