Commit f47841f8 authored by Yuchung Cheng's avatar Yuchung Cheng Committed by Sasha Levin

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

[ Upstream commit ed254971 ]

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: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent 24fd7957
...@@ -2536,8 +2536,8 @@ static inline void tcp_end_cwnd_reduction(struct sock *sk) ...@@ -2536,8 +2536,8 @@ static inline void tcp_end_cwnd_reduction(struct sock *sk)
struct tcp_sock *tp = tcp_sk(sk); struct tcp_sock *tp = tcp_sk(sk);
/* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */ /* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */
if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR || if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH &&
(tp->undo_marker && 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 = tp->snd_ssthresh;
tp->snd_cwnd_stamp = tcp_time_stamp; tp->snd_cwnd_stamp = tcp_time_stamp;
} }
......
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