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tcp_metrics: annotate data-races around tm->tcpm_lock

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[ Upstream commit 285ce119a3 ]

tm->tcpm_lock can be read or written locklessly.

Add needed READ_ONCE()/WRITE_ONCE() to document this.

Fixes: 51c5d0c4b1 ("tcp: Maintain dynamic metrics in local cache.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230802131500.1478140-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet
2023-08-02 13:14:57 +00:00
committed by Greg Kroah-Hartman
parent 289091eef3
commit 57bcbbb208
1 changed files with 4 additions and 2 deletions
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net/ipv4/tcp_metrics.c
+4 -2
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@@ -59,7 +59,8 @@ static inline struct net *tm_net(struct tcp_metrics_block *tm)
static bool tcp_metric_locked(struct tcp_metrics_block *tm, static bool tcp_metric_locked(struct tcp_metrics_block *tm,
enum tcp_metric_index idx) enum tcp_metric_index idx)
{ {
return tm->tcpm_lock & (1 << idx); /* Paired with WRITE_ONCE() in tcpm_suck_dst() */
return READ_ONCE(tm->tcpm_lock) & (1 << idx);
} }
static u32 tcp_metric_get(struct tcp_metrics_block *tm, static u32 tcp_metric_get(struct tcp_metrics_block *tm,
@@ -110,7 +111,8 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm,
val |= 1 << TCP_METRIC_CWND; val |= 1 << TCP_METRIC_CWND;
if (dst_metric_locked(dst, RTAX_REORDERING)) if (dst_metric_locked(dst, RTAX_REORDERING))
val |= 1 << TCP_METRIC_REORDERING; val |= 1 << TCP_METRIC_REORDERING;
tm->tcpm_lock = val; /* Paired with READ_ONCE() in tcp_metric_locked() */
WRITE_ONCE(tm->tcpm_lock, val);
msval = dst_metric_raw(dst, RTAX_RTT); msval = dst_metric_raw(dst, RTAX_RTT);
tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC; tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;