Re: [PATCHSET cgroup/for-3.16] cgroup: iterate cgroup_subsys_states directly

Li Zefan
2014-05-14T04:21:48Z

Hi Tejun,

On 2014/5/10 5:31, Tejun Heo wrote:
> Hello,
>
> Currently, while csses (cgroup_subsys_states) have ->parent linkage
> too, only cgroups form full tree through their ->children and
> ->sibling fields and css iterations naturally is implemented by
> iterating cgroups and then dereferencing the css for the specified
> subsystem.
>
> There are now use cases where controllers need to iterate through
> csses regardless of their online state as long as they have positive

What use cases are we talking about here?

> reference. This can't easily be achieved by iterating cgroups because
> its css pointer array needs to be cleared on offline and there may be
> multiple dying csses for a cgroup for the same subsystem and there's
> only one pointer per cgroup-subsystem pair.
>