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authorEric Dumazet <edumazet@google.com>2022-04-06 02:35:38 +0300
committerJakub Kicinski <kuba@kernel.org>2022-04-06 22:05:41 +0300
commit40570375356c874b1578e05c1dcc3ff7c1322dbe (patch)
tree54c7a52bfdd4e302f877e93dc94adb09cfa3aac4 /net/ipv4/tcp_veno.c
parent487dc3ca60e3e420d54bcc613cb49e8e85f34569 (diff)
downloadlinux-40570375356c874b1578e05c1dcc3ff7c1322dbe.tar.xz
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 <edumazet@google.com> Suggested-by: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_veno.c')
-rw-r--r--net/ipv4/tcp_veno.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c
index cd50a61c9976..366ff6f214b2 100644
--- a/net/ipv4/tcp_veno.c
+++ b/net/ipv4/tcp_veno.c
@@ -146,11 +146,11 @@ static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
rtt = veno->minrtt;
- target_cwnd = (u64)tp->snd_cwnd * veno->basertt;
+ target_cwnd = (u64)tcp_snd_cwnd(tp) * veno->basertt;
target_cwnd <<= V_PARAM_SHIFT;
do_div(target_cwnd, rtt);
- veno->diff = (tp->snd_cwnd << V_PARAM_SHIFT) - target_cwnd;
+ veno->diff = (tcp_snd_cwnd(tp) << V_PARAM_SHIFT) - target_cwnd;
if (tcp_in_slow_start(tp)) {
/* Slow start. */
@@ -164,15 +164,15 @@ static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
/* In the "non-congestive state", increase cwnd
* every rtt.
*/
- tcp_cong_avoid_ai(tp, tp->snd_cwnd, acked);
+ tcp_cong_avoid_ai(tp, tcp_snd_cwnd(tp), acked);
} else {
/* In the "congestive state", increase cwnd
* every other rtt.
*/
- if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+ if (tp->snd_cwnd_cnt >= tcp_snd_cwnd(tp)) {
if (veno->inc &&
- tp->snd_cwnd < tp->snd_cwnd_clamp) {
- tp->snd_cwnd++;
+ tcp_snd_cwnd(tp) < tp->snd_cwnd_clamp) {
+ tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) + 1);
veno->inc = 0;
} else
veno->inc = 1;
@@ -181,10 +181,10 @@ static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
tp->snd_cwnd_cnt += acked;
}
done:
- if (tp->snd_cwnd < 2)
- tp->snd_cwnd = 2;
- else if (tp->snd_cwnd > tp->snd_cwnd_clamp)
- tp->snd_cwnd = tp->snd_cwnd_clamp;
+ if (tcp_snd_cwnd(tp) < 2)
+ tcp_snd_cwnd_set(tp, 2);
+ else if (tcp_snd_cwnd(tp) > tp->snd_cwnd_clamp)
+ tcp_snd_cwnd_set(tp, tp->snd_cwnd_clamp);
}
/* Wipe the slate clean for the next rtt. */
/* veno->cntrtt = 0; */
@@ -199,10 +199,10 @@ static u32 tcp_veno_ssthresh(struct sock *sk)
if (veno->diff < beta)
/* in "non-congestive state", cut cwnd by 1/5 */
- return max(tp->snd_cwnd * 4 / 5, 2U);
+ return max(tcp_snd_cwnd(tp) * 4 / 5, 2U);
else
/* in "congestive state", cut cwnd by 1/2 */
- return max(tp->snd_cwnd >> 1U, 2U);
+ return max(tcp_snd_cwnd(tp) >> 1U, 2U);
}
static struct tcp_congestion_ops tcp_veno __read_mostly = {