Merge remote-tracking branch 'rt-stable/v4.9-rt' into linux-linaro-lsk-v4.9-rtlsk-v4.9-17.11-rt

1 files changed, 9 insertions, 3 deletions

diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
index 9a1a352fd1eb..77f396b679ce 100644
--- a/net/core/sock_reuseport.c
+++ b/net/core/sock_reuseport.c
@@ -36,9 +36,14 @@ int reuseport_alloc(struct sock *sk)
 	 * soft irq of receive path or setsockopt from process context
 	 */
 	spin_lock_bh(&reuseport_lock);
-	WARN_ONCE(rcu_dereference_protected(sk->sk_reuseport_cb,
-					    lockdep_is_held(&reuseport_lock)),
-		  "multiple allocations for the same socket");
+
+	/* Allocation attempts can occur concurrently via the setsockopt path
+	 * and the bind/hash path.  Nothing to do when we lose the race.
+	 */
+	if (rcu_dereference_protected(sk->sk_reuseport_cb,
+				      lockdep_is_held(&reuseport_lock)))
+		goto out;
+
 	reuse = __reuseport_alloc(INIT_SOCKS);
 	if (!reuse) {
 		spin_unlock_bh(&reuseport_lock);
@@ -49,6 +54,7 @@ int reuseport_alloc(struct sock *sk)
 	reuse->num_socks = 1;
 	rcu_assign_pointer(sk->sk_reuseport_cb, reuse);
 
+out:
 	spin_unlock_bh(&reuseport_lock);
 
 	return 0;