Re: [PATCH 15/23] cgroup: make hierarchy iterators deal with cgroup_subsys_state instead of cgroup

[Aristeu Rozanski <aris@redhat.com>]

On Thu, Aug 01, 2013 at 05:49:53PM -0400, Tejun Heo wrote:
> cgroup is currently in the process of transitioning to using css
> (cgroup_subsys_state) as the primary handle instead of cgroup in
> subsystem API.  For hierarchy iterators, this is beneficial because
> 
> * In most cases, css is the only thing subsystems care about anyway.
> 
> * On the planned unified hierarchy, iterations for different
>   subsystems will need to skip over different subtrees of the
>   hierarchy depending on which subsystems are enabled on each cgroup.
>   Passing around css makes it unnecessary to explicitly specify the
>   subsystem in question as css is intersection between cgroup and
>   subsystem
> 
> * For the planned unified hierarchy, css's would need to be created
>   and destroyed dynamically independent from cgroup hierarchy.  Having
>   cgroup core manage css iteration makes enforcing deref rules a lot
>   easier.
> 
> Most subsystem conversions are straight-forward.  Noteworthy changes
> are
> 
> * blkio: cgroup_to_blkcg() is no longer used.  Removed.
> 
> * freezer: cgroup_freezer() is no longer used.  Removed.
> 
> * devices: cgroup_to_devcgroup() is no longer used.  Removed.

Acked-by: Aristeu Rozanski <aris@redhat.com>

-- 
Aristeu