net_sched: em_meta: add READ_ONCE() in var_sk_bound_if()

sk->sk_bound_dev_if can change under us, use READ_ONCE() annotation.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sched/em_meta.c

@@ -311,12 +311,15 @@ META_COLLECTOR(int_sk_bound_if)
 
 META_COLLECTOR(var_sk_bound_if)
 {
+	int bound_dev_if;
+
 	if (skip_nonlocal(skb)) {
 		*err = -1;
 		return;
 	}
 
-	if (skb->sk->sk_bound_dev_if == 0) {
+	bound_dev_if = READ_ONCE(skb->sk->sk_bound_dev_if);
+	if (bound_dev_if == 0) {
 		dst->value = (unsigned long) "any";
 		dst->len = 3;
 	} else {
@@ -324,7 +327,7 @@ META_COLLECTOR(var_sk_bound_if)
 
 		rcu_read_lock();
 		dev = dev_get_by_index_rcu(sock_net(skb->sk),
-					   skb->sk->sk_bound_dev_if);
+					   bound_dev_if);
 		*err = var_dev(dev, dst);
 		rcu_read_unlock();
 	}