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Commit 6d49ed95 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
Browse files

tcp_metrics: annotate data-races around tm->tcpm_net 



[ Upstream commit d5d986ce42c71a7562d32c4e21e026b0f87befec ]

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: 849e8a0c ("tcp_metrics: Add a field tcpm_net and verify it matches on lookup")
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/20230802131500.1478140-6-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent fc566cf3

net/ipv4/tcp_metrics.c

+7 −4
Original line number Diff line number Diff line
@@ -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;