From 40570375356c874b1578e05c1dcc3ff7c1322dbe Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 5 Apr 2022 16:35:38 -0700 Subject: tcp: add accessors to read/set tp->snd_cwnd We had various bugs over the years with code breaking the assumption that tp->snd_cwnd is greater than zero. Lately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added in commit 8b8a321ff72c ("tcp: fix zero cwnd in tcp_cwnd_reduction") can trigger, and without a repro we would have to spend considerable time finding the bug. Instead of complaining too late, we want to catch where and when tp->snd_cwnd is set to an illegal value. Signed-off-by: Eric Dumazet Suggested-by: Yuchung Cheng Cc: Neal Cardwell Acked-by: Yuchung Cheng Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski --- net/ipv4/tcp_lp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net/ipv4/tcp_lp.c') diff --git a/net/ipv4/tcp_lp.c b/net/ipv4/tcp_lp.c index 82b36ec3f2f8..ae36780977d2 100644 --- a/net/ipv4/tcp_lp.c +++ b/net/ipv4/tcp_lp.c @@ -297,7 +297,7 @@ static void tcp_lp_pkts_acked(struct sock *sk, const struct ack_sample *sample) lp->flag &= ~LP_WITHIN_THR; pr_debug("TCP-LP: %05o|%5u|%5u|%15u|%15u|%15u\n", lp->flag, - tp->snd_cwnd, lp->remote_hz, lp->owd_min, lp->owd_max, + tcp_snd_cwnd(tp), lp->remote_hz, lp->owd_min, lp->owd_max, lp->sowd >> 3); if (lp->flag & LP_WITHIN_THR) @@ -313,12 +313,12 @@ static void tcp_lp_pkts_acked(struct sock *sk, const struct ack_sample *sample) /* happened within inference * drop snd_cwnd into 1 */ if (lp->flag & LP_WITHIN_INF) - tp->snd_cwnd = 1U; + tcp_snd_cwnd_set(tp, 1U); /* happened after inference * cut snd_cwnd into half */ else - tp->snd_cwnd = max(tp->snd_cwnd >> 1U, 1U); + tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp) >> 1U, 1U)); /* record this drop time */ lp->last_drop = now; -- cgit v1.2.3