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authorYuchung Cheng <ycheng@google.com>2012-04-30 06:00:18 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-12 09:32:19 -0700
commit28a3d46497af5da64dd88110bf03d99cf181d5f9 (patch)
tree5c84ac7763af530a1f9798564539b27763927a5e
parentac931e2df86c0f7e69df21001832ad63ffe3d1c9 (diff)
tcp: fix infinite cwnd in tcp_complete_cwr()
[ Upstream commit 1cebce36d660c83bd1353e41f3e66abd4686f215 ] 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> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/ipv4/tcp_input.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 1c30511e9c32..210f474b4fe3 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2866,11 +2866,14 @@ 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);
}