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tcp_metrics: annotate data-races around tm->tcpm_net 

tm->tcpm_net can be read or written locklessly.

Instead of changing write_pnet() and read_pnet() and potentially
hurt performance, add the needed READ_ONCE()/WRITE_ONCE()
in tm_net() and tcpm_new().

Fixes: 849e8a0ca8 ("tcp_metrics: Add a field tcpm_net and verify it matches on lookup")
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/20230802131500.1478140-6-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2023-08-02 13:14:59 +00:00 committed by Jakub Kicinski
parent 8c4d04f6b4
commit d5d986ce42
1 changed files with 7 additions and 4 deletions
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11
net/ipv4/tcp_metrics.c
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@ -40,7 +40,7 @@ struct tcp_fastopen_metrics {
struct tcp_metrics_block {
struct tcp_metrics_block __rcu *tcpm_next;
possible_net_t tcpm_net;
struct net *tcpm_net;
struct inetpeer_addr tcpm_saddr;
struct inetpeer_addr tcpm_daddr;
unsigned long tcpm_stamp;
@ -51,9 +51,10 @@ struct tcp_metrics_block {
struct rcu_head rcu_head;
};
static inline struct net *tm_net(struct tcp_metrics_block *tm)
static inline struct net *tm_net(const struct tcp_metrics_block *tm)
{
return read_pnet(&tm->tcpm_net);
/* Paired with the WRITE_ONCE() in tcpm_new() */
return READ_ONCE(tm->tcpm_net);
}
static bool tcp_metric_locked(struct tcp_metrics_block *tm,
@ -197,7 +198,9 @@ static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
if (!tm)
goto out_unlock;
}
write_pnet(&tm->tcpm_net, net);
/* Paired with the READ_ONCE() in tm_net() */
WRITE_ONCE(tm->tcpm_net, net);
tm->tcpm_saddr = *saddr;
tm->tcpm_daddr = *daddr;