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Commit 72c97e54 authored Aug 08, 2013 by Tejun Heo

cgroup: add subsystem pointer to cgroup_subsys_state



Currently, given a cgroup_subsys_state, there's no way to find out
which subsystem the css is for, which we'll need to convert the cgroup
controller API to primarily use @css instead of @cgroup.  This patch
adds cgroup_subsys_state->ss which points to the subsystem the @css
belongs to.

While at it, remove the comment about accessing @css->cgroup to
determine the hierarchy.  cgroup core will provide API to traverse
hierarchy of css'es and we don't want subsystems to directly walk
cgroup hierarchies anymore.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

parent 3f798518

include/linux/cgroup.h

+4 −5

Original line number	Diff line number	Diff line
		@@ -66,13 +66,12 @@ enum cgroup_subsys_id {

		/* Per-subsystem/per-cgroup state maintained by the system. */
		struct cgroup_subsys_state {
		/*
		* The cgroup that this subsystem is attached to. Useful
		* for subsystems that want to know about the cgroup
		* hierarchy structure
		*/
		/* the cgroup that this css is attached to */
		struct cgroup *cgroup;

		/* the cgroup subsystem that this css is attached to */
		struct cgroup_subsys *ss;

		/* reference count - access via css_[try]get() and css_put() */
		struct percpu_ref refcnt;

kernel/cgroup.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -4186,6 +4186,7 @@ static void init_cgroup_css(struct cgroup_subsys_state *css,
		struct cgroup *cgrp)
		{
		css->cgroup = cgrp;
		css->ss = ss;
		css->flags = 0;
		css->id = NULL;
		if (cgrp == cgroup_dummy_top)