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authorYuchung Cheng <ycheng@google.com>2017-08-01 13:22:32 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-08-12 19:34:26 -0700
commit4fe3624211f7860b5d7b83fa04d71e85755a9244 (patch)
tree6479a7587c030e782c66d1f59590adc273c465be
parent5028e6c9c5cea3b2be222f28ab1d11d932bc6e81 (diff)
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tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states
[ Upstream commit ed254971edea92c3ac5c67c6a05247a92aa6075e ] If the sender switches the congestion control during ECN-triggered cwnd-reduction state (CA_CWR), upon exiting recovery cwnd is set to the ssthresh value calculated by the previous congestion control. If the previous congestion control is BBR that always keep ssthresh to TCP_INIFINITE_SSTHRESH, cwnd ends up being infinite. The safe step is to avoid assigning invalid ssthresh value when recovery ends. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@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.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 174d4376baa5..57bcae81fe42 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2517,8 +2517,8 @@ static inline void tcp_end_cwnd_reduction(struct sock *sk)
return;
/* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */
- if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR ||
- (tp->undo_marker && tp->snd_ssthresh < TCP_INFINITE_SSTHRESH)) {
+ if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH &&
+ (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR || tp->undo_marker)) {
tp->snd_cwnd = tp->snd_ssthresh;
tp->snd_cwnd_stamp = tcp_time_stamp;
}