diff options
| author |   Yuchung Cheng <ycheng@google.com> | 2017-08-03 20:38:51 -0700 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-08-06 21:25:10 -0700 |
| commit | 4faf783998b8cb88294e9df89032f473f8771b78 (patch) | |
| tree | 0ad450f18cbf6c23f23e9f181a4d4ee5c6a99b7a /net/ipv4/tcp_input.c | |
| parent | net: systemport: Support 64bit statistics (diff) | |
| download | linux-dev-4faf783998b8cb88294e9df89032f473f8771b78.tar.xz linux-dev-4faf783998b8cb88294e9df89032f473f8771b78.zip | |
tcp: fix cwnd undo in Reno and HTCP congestion controls
Using ssthresh to revert cwnd is less reliable when ssthresh is
bounded to 2 packets. This patch uses an existing variable in TCP
"prior_cwnd" that snapshots the cwnd right before entering fast
recovery and RTO recovery in Reno. This fixes the issue discussed
in netdev thread: "A buggy behavior for Linux TCP Reno and HTCP"
https://www.spinics.net/lists/netdev/msg444955.html
Suggested-by: Neal Cardwell <ncardwell@google.com>
Reported-by: Wei Sun <unlcsewsun@gmail.com>
Signed-off-by: Yuchung Cheng <ncardwell@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 99cdf4ccabb8..842ed75ccb25 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1950,6 +1950,7 @@ void tcp_enter_loss(struct sock *sk) !after(tp->high_seq, tp->snd_una) || (icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) { tp->prior_ssthresh = tcp_current_ssthresh(sk); + tp->prior_cwnd = tp->snd_cwnd; tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk); tcp_ca_event(sk, CA_EVENT_LOSS); tcp_init_undo(tp); |