tcp: avoid setting cwnd to invalid ssthresh after cwnd reduction states

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 <[email protected]>
Signed-off-by: Neal Cardwell <[email protected]>
Acked-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
This commit is contained in:
Yuchung Cheng 2017-08-01 13:22:32 -07:00 • committed by David S. Miller
commit ed254971ed

View file

@ -2520,8 +2520,8 @@ 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_jiffies32;
}