Lai Jiangshan 96e65306b8 workqueue: UNBOUND -> REBIND morphing in rebind_workers() should be atomic
The compiler may compile the following code into TWO write/modify
instructions.

	worker->flags &= ~WORKER_UNBOUND;
	worker->flags |= WORKER_REBIND;

so the other CPU may temporarily see worker->flags which doesn't have
either WORKER_UNBOUND or WORKER_REBIND set and perform local wakeup
prematurely.

Fix it by using single explicit assignment via ACCESS_ONCE().

Because idle workers have another WORKER_NOT_RUNNING flag, this bug
doesn't exist for them; however, update it to use the same pattern for
consistency.

tj: Applied the change to idle workers too and updated comments and
    patch description a bit.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
2012-09-04 17:04:45 -07:00
..
2011-07-26 16:49:45 -07:00
2012-07-31 20:44:03 -07:00
2012-07-26 11:14:49 -07:00
2012-07-14 16:35:02 +04:00
2012-05-21 23:52:30 -04:00
2012-05-31 17:49:27 -07:00
2011-07-14 12:59:14 +03:00
2012-03-28 18:30:03 +01:00
2012-07-31 18:42:43 -07:00
2012-05-31 17:49:32 -07:00
2012-05-29 23:28:41 -04:00
2012-03-29 19:52:46 +08:00
2012-06-13 21:16:42 +02:00
2012-03-28 18:30:03 +01:00
2012-06-11 15:07:52 +02:00
2012-05-31 17:49:32 -07:00
2012-07-30 17:25:13 -07:00
2012-03-15 18:17:55 -07:00
2012-05-19 15:44:40 -06:00