[PATCH] workqueue: clear leftover flags when detached

[PATCH] workqueue: clear leftover flags when detached

[Lai Jiangshan]

When a worker is detached, the worker->flags may still have WORKER_UNBOUND
or WORKER_REBOUND, it is OK for all cases:
  1) if it is a normal worker, the worker will be dead, it is OK.
  2) if it is a rescuer, it may re-attach to a pool with this leftover flag[s],
     it is still correct except it may cause unneeded wakeup.

It is correct but not good, so we just remove the leftover flags.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
 kernel/workqueue.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 7dc6e66..9f53abd 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1663,6 +1663,9 @@ static void worker_detach_from_pool(struct worker *worker,
 		detach_completion = pool->detach_completion;
 	mutex_unlock(&pool->attach_mutex);
 
+	/* clear leftover flags without pool->lock after it is detached */
+	worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND);
+
 	if (detach_completion)
 		complete(detach_completion);
 }
-- 
1.7.4.4

Re: [PATCH] workqueue: clear leftover flags when detached

[Tejun Heo]

On Tue, Jun 03, 2014 at 03:32:52PM +0800, Lai Jiangshan wrote:
> When a worker is detached, the worker->flags may still have WORKER_UNBOUND
> or WORKER_REBOUND, it is OK for all cases:
>   1) if it is a normal worker, the worker will be dead, it is OK.
>   2) if it is a rescuer, it may re-attach to a pool with this leftover flag[s],
>      it is still correct except it may cause unneeded wakeup.
> 
> It is correct but not good, so we just remove the leftover flags.
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>

Applied to wq/for-3.17.

Thanks.

-- 
tejun