linux-kernel - [PATCH] workqueue: clear leftover flags when detached

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Date:	Tue, 3 Jun 2014 15:32:52 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	<linux-kernel@...r.kernel.org>
CC:	Tejun Heo <tj@...nel.org>, Lai Jiangshan <laijs@...fujitsu.com>
Subject: [PATCH] workqueue: clear leftover flags when detached

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@...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

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