Messages in this thread | | | Date | Mon, 18 May 2015 17:34:23 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH v12 7/8] cgroup: add a tset_get_css macro |
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On Tue, May 19, 2015 at 12:51:06AM +1000, Aleksa Sarai wrote: > This adds a macro to get the css of a tset (using task_get_css()) by > just grabbing a ref to the first item in the tset (since there is a > guarantee that all tasks in a tset share a css). > > This is in preparation for implementing the pids cgroup subsystem. > > Signed-off-by: Aleksa Sarai <cyphar@cyphar.com> > --- > include/linux/cgroup.h | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h > index 886a883..773846d 100644 > --- a/include/linux/cgroup.h > +++ b/include/linux/cgroup.h > @@ -639,6 +639,18 @@ struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset); > for ((task) = cgroup_taskset_first((tset)); (task); \ > (task) = cgroup_taskset_next((tset))) > > +/** > + * tset_get_css - obtain and get css for (tset, subsys_id) > + * @tset: target taskset > + * @subsys_id: target subsystem id > + * > + * Since all of the tasks in a taskset are guaranteed to have the same css, it's > + * safe to grab the ref of just the first task's css and treat it as though you > + * have a ref on the taskset's "collective" css. > + */ > +#define tset_get_css(tset, subsys_id) \ > + task_get_css(cgroup_taskset_first(tset), subsys_id)
They aren't tho. It depends on the hierarchy configuration. csses belonging to hierarchies which aren't the current migration target may differ.
Thanks.
-- tejun
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