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Message-Id: <20220801114139.191743400@linuxfoundation.org>
Date: Mon, 1 Aug 2022 13:46:39 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Kuniyuki Iwashima <kuniyu@...zon.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.18 25/88] tcp: Fix data-races around sysctl_tcp_no_ssthresh_metrics_save.
From: Kuniyuki Iwashima <kuniyu@...zon.com>
commit ab1ba21b523ab496b1a4a8e396333b24b0a18f9a upstream.
While reading sysctl_tcp_no_ssthresh_metrics_save, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.
Fixes: 65e6d90168f3 ("net-tcp: Disable TCP ssthresh metrics cache by default")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/ipv4/tcp_metrics.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -385,7 +385,7 @@ void tcp_update_metrics(struct sock *sk)
if (tcp_in_initial_slowstart(tp)) {
/* Slow start still did not finish. */
- if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
+ if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
if (val && (tcp_snd_cwnd(tp) >> 1) > val)
@@ -401,7 +401,7 @@ void tcp_update_metrics(struct sock *sk)
} else if (!tcp_in_slow_start(tp) &&
icsk->icsk_ca_state == TCP_CA_Open) {
/* Cong. avoidance phase, cwnd is reliable. */
- if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
+ if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
max(tcp_snd_cwnd(tp) >> 1, tp->snd_ssthresh));
@@ -418,7 +418,7 @@ void tcp_update_metrics(struct sock *sk)
tcp_metric_set(tm, TCP_METRIC_CWND,
(val + tp->snd_ssthresh) >> 1);
}
- if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
+ if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
if (val && tp->snd_ssthresh > val)
@@ -463,7 +463,7 @@ void tcp_init_metrics(struct sock *sk)
if (tcp_metric_locked(tm, TCP_METRIC_CWND))
tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
- val = net->ipv4.sysctl_tcp_no_ssthresh_metrics_save ?
+ val = READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) ?
0 : tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
if (val) {
tp->snd_ssthresh = val;
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