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tcp_metrics: annotate data-races around tm->tcpm_lock 

[ 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 4a77a0f752
commit fee608e802
1 changed files with 4 additions and 2 deletions
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6
net/ipv4/tcp_metrics.c
View File

@ -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;