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/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 0ee725c..9eae04af 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -599,9 +599,9 @@
 	set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_rx);
 	write_unlock_bh(&tcp_sw_conn->sock->sk->sk_callback_lock);
 
-	if (sock->sk->sk_sleep && waitqueue_active(sock->sk->sk_sleep)) {
+	if (sk_sleep(sock->sk) && waitqueue_active(sk_sleep(sock->sk))) {
 		sock->sk->sk_err = EIO;
-		wake_up_interruptible(sock->sk->sk_sleep);
+		wake_up_interruptible(sk_sleep(sock->sk));
 	}
 
 	iscsi_conn_stop(cls_conn, flag);