tree be35c2daec953f0c98241c16311879dd45bc4859
parent f50daa704f36a6544a902c52b6cf37b0493dfc5d
author Li Zefan <lizefan@huawei.com> 1362452223 +0800
committer Tejun Heo <tj@kernel.org> 1362504805 -0800

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>