[PATCH 4.20 45/76] tun: fix blocking read

Greg Kroah-Hartman
2019-03-08T13:06:36Z

From: Timur Celik <mail@timurcelik.de>

[ 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>
---
drivers/net/tun.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2147,9 +2147,9 @@ static void *tun_ring_recv(struct tun_fi
}

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_fi
schedule();
}

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