net: Generalise wq_has_sleeper helper

The memory barrier in the helper wq_has_sleeper is needed by just
about every user of waitqueue_active.  This patch generalises it
by making it take a wait_queue_head_t directly.  The existing
helper is renamed to skwq_has_sleeper.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index 1f8a144..7e2d105 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -67,7 +67,7 @@
 	if (rxrpc_writable(sk)) {
 		struct socket_wq *wq = rcu_dereference(sk->sk_wq);
 
-		if (wq_has_sleeper(wq))
+		if (skwq_has_sleeper(wq))
 			wake_up_interruptible(&wq->wait);
 		sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
 	}