From: yanhai zhu <zhu.yanhai@gmail.com>
Date: Wed, 12 Nov 2008 19:36:58 +0000 (-0500)
Subject: Btrfs: Check kthread_should_stop() before schedule() in worker_loop
X-Git-Tag: v2.6.29-rc1~27^2~9^2~55^2~14
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=0df49b911db2b22ea808b596070b1cc65c23d148;p=linux.git

Btrfs: Check kthread_should_stop() before schedule() in worker_loop

In worker_loop(), the func should check whether it has been requested to stop
before it decides to schedule out.

Otherwise if the stop request(also the last wake_up()) sent by
btrfs_stop_workers() happens when worker_loop() running after the "while"
judgement and before schedule(), woker_loop() will schedule away and never be
woken up, which will also cause btrfs_stop_workers() wait forever.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
---

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index e1e49715459e..4229450b7596 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -171,7 +171,8 @@ static int worker_loop(void *arg)
 		} else {
 			set_current_state(TASK_INTERRUPTIBLE);
 			spin_unlock_irq(&worker->lock);
-			schedule();
+			if (!kthread_should_stop())
+				schedule();
 			__set_current_state(TASK_RUNNING);
 		}
 	} while (!kthread_should_stop());