tun: fix blocking read

[ Upstream commit 71828b22 ]

This patch moves setting of the current state into the loop. Otherwise
the task may end up in a busy wait loop if none of the break conditions
are met.
Signed-off-by: Timur Celik <mail@timurcelik.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/tun.c

@@ -1471,9 +1471,9 @@ static struct sk_buff *tun_ring_recv(struct tun_file *tfile, int noblock,
 	}
 
 	add_wait_queue(&tfile->wq.wait, &wait);
-	current->state = TASK_INTERRUPTIBLE;
 
 	while (1) {
+		set_current_state(TASK_INTERRUPTIBLE);
 		skb = skb_array_consume(&tfile->tx_array);
 		if (skb)
 			break;
@@ -1489,7 +1489,7 @@ static struct sk_buff *tun_ring_recv(struct tun_file *tfile, int noblock,
 		schedule();
 	}
 
-	current->state = TASK_RUNNING;
+	set_current_state(TASK_RUNNING);
 	remove_wait_queue(&tfile->wq.wait, &wait);
 
 out: