From: Eric Dumazet edumazet@google.com
[ 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: 849e8a0ca8d5 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/tcp_metrics.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c index fd4ab7a51cef2..4fd274836a48f 100644 --- a/net/ipv4/tcp_metrics.c +++ b/net/ipv4/tcp_metrics.c @@ -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;