tree b6d880e578cd07db0d60a8dee86c28d67abb446c
parent a0111cf6710bd1b4145ef313d3f4772602af051b
author Lai Jiangshan <laijs@cn.fujitsu.com> 1432029828 +0800
committer Tejun Heo <tj@kernel.org> 1432071420 -0400

workqueue: ensure attrs changes are properly synchronized

Current modification to attrs via sysfs is not fully synchronized.

Process A (change cpumask)      | Process B (change numa affinity)
wq_cpumask_store()              |
  wq_sysfs_prep_attrs()         |
                                | apply_workqueue_attrs()
  apply_workqueue_attrs()       |

It results that the Process B's operation is totally reverted
without any notification, it is a buggy behavior.  So this patch
moves wq_sysfs_prep_attrs() into the protection under wq_pool_mutex
to ensure attrs changes are properly synchronized.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>