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/recv.c b/net/rds/recv.c
index e2a2b93..795a00b 100644
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -432,7 +432,7 @@
 				break;
 			}
 
-			timeo = wait_event_interruptible_timeout(*sk->sk_sleep,
+			timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
 					(!list_empty(&rs->rs_notify_queue) ||
 					 rs->rs_cong_notify ||
 					 rds_next_incoming(rs, &inc)), timeo);