Messages in this thread | | | Date | Wed, 31 Aug 2011 23:54:26 +0200 | From | Frederic Weisbecker <> | Subject | Re: [RFD] Task counter: cgroup core feature or cgroup subsystem? (was Re: [PATCH 0/8 v3] cgroups: Task counter subsystem) |
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On Fri, Aug 26, 2011 at 08:16:32AM -0700, Paul Menage wrote: > On Wed, Aug 24, 2011 at 10:54 AM, Frederic Weisbecker > <fweisbec@gmail.com> wrote: > > > > It seems your patch doesn't handle the ->fork() and ->exit() calls. > > We probably need a quick access to states of multi-subsystems from > > the task, some lists available from task->cgroups, I don't know yet. > > > > That state is available, but currently only while holding cgroup_mutex > - at least, that's what task_cgroup_from_root() requires. > > It might be the case that we could achieve the same effect by just > locking the task, so the pre-condition for task_cgroup_from_root() > would be either that cgroup_mutex is held or the task lock is held.
Now I realize, is it necessary if we only want to access a subsys state through task->cgroups->subsys[i] from the ->fork() callback?
The task is not yet added to the thread_group, its pid is not yet hashed so I guess it can not concurrently be moved to another cgroup.
We need a special flavour of task->cgroups->subsys for multi bindable subsystem but that's the same.
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