[PATCH 4.14 031/135] tun: fix blocking read

From: Greg Kroah-Hartman
Date: Tue Mar 12 2019 - 13:16:54 EST


4.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Timur Celik <mail@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/tun.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1714,9 +1714,9 @@ static struct sk_buff *tun_ring_recv(str
}

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;
@@ -1732,7 +1732,7 @@ static struct sk_buff *tun_ring_recv(str
schedule();
}

- current->state = TASK_RUNNING;
+ set_current_state(TASK_RUNNING);
remove_wait_queue(&tfile->wq.wait, &wait);

out: