net: use WARN_ON_ONCE() in sk_stream_kill_queues()

sk_stream_kill_queues() has three checks which have been
useful to detect kernel bugs in the past.

However they are potentially a problem because they
could flood the syslog.

Signed-off-by: Eric Dumazet <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

net/core/stream.c

···
 	__skb_queue_purge(&sk->sk_receive_queue);
 
 	/* Next, the write queue. */
-	WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
+	WARN_ON_ONCE(!skb_queue_empty(&sk->sk_write_queue));
 
 	/* Account for returned memory. */
 	sk_mem_reclaim_final(sk);
 
-	WARN_ON(sk->sk_wmem_queued);
-	WARN_ON(sk->sk_forward_alloc);
+	WARN_ON_ONCE(sk->sk_wmem_queued);
+	WARN_ON_ONCE(sk->sk_forward_alloc);
 
 	/* It is _impossible_ for the backlog to contain anything
 	 * when we get here.  All user references to this socket