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/rds/rds.h b/net/rds/rds.h
index 4bec6e2..c224b5b 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -492,7 +492,7 @@
 void rds_wake_sk_sleep(struct rds_sock *rs);
 static inline void __rds_wake_sk_sleep(struct sock *sk)
 {
-	wait_queue_head_t *waitq = sk->sk_sleep;
+	wait_queue_head_t *waitq = sk_sleep(sk);
 
 	if (!sock_flag(sk, SOCK_DEAD) && waitq)
 		wake_up(waitq);