From: Li Zefan <lizefan@huawei.com>
Date: Tue, 5 Mar 2013 02:57:03 +0000 (+0800)
Subject: cgroup: avoid accessing modular cgroup subsys structure without locking
X-Git-Tag: omap-for-v3.10/dt-fixes-for-merge-window~124^2~41
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7d8e0bf56a66bab08d2f316dd87e56c08cecb899;p=pandora-kernel.git

cgroup: avoid accessing modular cgroup subsys structure without locking

subsys[i] is set to NULL in cgroup_unload_subsys() at modular unload,
and that's protected by cgroup_mutex, and then the memory *subsys[i]
resides will be freed.

So this is unsafe without any locking:

  if (!ss || ss->module)
  ...

v2:
- add a comment for enum cgroup_subsys_id
- simplify the comment in cgroup_exit()

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---

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