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/dccp/proto.c b/net/dccp/proto.c
index a0e38d8..b03ecf6 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -312,7 +312,7 @@
 	unsigned int mask;
 	struct sock *sk = sock->sk;
 
-	sock_poll_wait(file, sk->sk_sleep, wait);
+	sock_poll_wait(file, sk_sleep(sk), wait);
 	if (sk->sk_state == DCCP_LISTEN)
 		return inet_csk_listen_poll(sk);