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Commit 76b47dab authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
Browse files

tcp_metrics: annotate data-races around tm->tcpm_lock 



[ Upstream commit 285ce119a3c6c4502585936650143e54c8692788 ]

tm->tcpm_lock can be read or written locklessly.

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

Fixes: 51c5d0c4 ("tcp: Maintain dynamic metrics in local cache.")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230802131500.1478140-4-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 38661fe6

net/ipv4/tcp_metrics.c

+4 −2
Original line number Diff line number Diff line
@@ -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,

			      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,
@@ -110,7 +111,8 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm, 
		val |= 1 << TCP_METRIC_CWND;

	if (dst_metric_locked(dst, RTAX_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);

	tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;