Re: [PATCH 7/7] cgroups: Update documentation for bindable subsystems

[Li Zefan <lizf@cn.fujitsu.com>]

Paul Menage wrote:
>>  Called when a cgroup subsystem is rebound to a different hierarchy
>> -and root cgroup. Currently this will only involve movement between
>> -the default hierarchy (which never has sub-cgroups) and a hierarchy
>> -that is being created/destroyed (and hence has no sub-cgroups).
>> +and root cgroup. For some subsystems this will only involve movement
>> +between the default hierarchy (which never has sub-cgroups) and a
>> +hierarchy that is being created/destroyed (and hence has no sub-cgroups).
>> +For some other subsystems this can involve movement between the default
>> +hierarchy and a mounted hierarchy which may have sub-cgroups in it.
> 
> This is a bit vague. How about:
> 
> For non-bindable subsystems, this will  only involve movement
> between the default hierarchy (which never has sub-cgroups) and a
> hierarchy that is being created/destroyed (and hence has no sub-cgroups).
> 
> For binadable subsystems, this may also involve movement between the
> default hierarchy and a mounted hierarchy that's populated with
> sub-cgroups.
> 
> Also, the docs should mention that a cgroup setting the can_bind flag
> has to be able to support side-effect free movement of a task into any
> just-created cgroup, and into the root cgroup at any time. i.e. it's
> not suitable for any subsystem where can_attach() might return false
> for the root cgroup or a newly-created cgroup, or attach() might have
> side-effects for those same cases.
> 
> Actually, perhaps we should forbid the combination of having both an
> attach() callback and can_bind=true ?
> 
> Also, post_clone() doesn't get called when creating the css hierarchy
> during binding.
> 

This is much better. :)

Documentation often causes my headache due to my limited English skill.