net: sk_sleep() helper

Define a new function to return the waitqueue of a "struct sock".

static inline wait_queue_head_t *sk_sleep(struct sock *sk)
{
	return sk->sk_sleep;
}

Change all read occurrences of sk_sleep by a call to this function.

Needed for a future RCU conversion. sk_sleep wont be a field directly
available.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index c060095b..c432d76 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -65,7 +65,7 @@
 	read_lock(&sk->sk_callback_lock);
 	if (rxrpc_writable(sk)) {
 		if (sk_has_sleeper(sk))
-			wake_up_interruptible(sk->sk_sleep);
+			wake_up_interruptible(sk_sleep(sk));
 		sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
 	}
 	read_unlock(&sk->sk_callback_lock);
@@ -589,7 +589,7 @@
 	unsigned int mask;
 	struct sock *sk = sock->sk;
 
-	sock_poll_wait(file, sk->sk_sleep, wait);
+	sock_poll_wait(file, sk_sleep(sk), wait);
 	mask = 0;
 
 	/* the socket is readable if there are any messages waiting on the Rx