From: Timur Celik <mail@timurcelik.de>
Date: Sat, 23 Feb 2019 11:53:13 +0000 (+0100)
Subject: tun: fix blocking read
X-Git-Tag: v4.20.15~32
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8b2bc50ee00f3707321676f52a4415201fbf015d;p=thirdparty%2Fkernel%2Fstable.git

tun: fix blocking read

[ Upstream commit 71828b2240692cec0e68b8d867bc00e1745e7fae ]

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>
---

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 1e6f0da1fa8e7..05728e583d90c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2147,9 +2147,9 @@ static void *tun_ring_recv(struct tun_file *tfile, int noblock, int *err)
 	}
 
 	add_wait_queue(&tfile->wq.wait, &wait);
-	current->state = TASK_INTERRUPTIBLE;
 
 	while (1) {
+		set_current_state(TASK_INTERRUPTIBLE);
 		ptr = ptr_ring_consume(&tfile->tx_ring);
 		if (ptr)
 			break;
@@ -2165,7 +2165,7 @@ static void *tun_ring_recv(struct tun_file *tfile, int noblock, int *err)
 		schedule();
 	}
 
-	current->state = TASK_RUNNING;
+	set_current_state(TASK_RUNNING);
 	remove_wait_queue(&tfile->wq.wait, &wait);
 
 out: