Re: [PATCH v2] cgroup: Remove task_lock() from cgroup_post_fork()

[Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>]

Tejun Heo wrote:
> On Fri, Dec 23, 2011 at 04:25:23AM +0100, Frederic Weisbecker wrote:
>> cgroup_post_fork() is protected between threadgroup_change_begin()
>> and threadgroup_change_end() against concurrent changes of the
>> child's css_set in cgroup_task_migrate(). Also the child can't
>> exit and call cgroup_exit() at this stage, this means it's css_set
>> can't be changed with init_css_set concurrently.
>>
>> For these reasons, we don't need to hold task_lock() on the child
>> because it's css_set can only remain stable in this place.
>>
>> Let's remove the lock there.
>>
>> v2: Update comment to explain that we are safe against
>> cgroup_exit()
>>
>> Signed-off-by: Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> Cc: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
>> Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>> Cc: Containers <containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
>> Cc: Cgroups <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
>> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
>> Cc: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
>> Cc: Paul Menage <paul-inf54ven1CmVyaH7bEyXVA@public.gmane.org>
>> Cc: Mandeep Singh Baines <msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> 
> Li, does this look good to you?
> 

Acked-by: Li Zefan <lizf-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>