Commit 0679dee0 authored by Roman Gushchin's avatar Roman Gushchin Committed by Tejun Heo
Browse files

cgroup: keep track of number of descent cgroups 



Keep track of the number of online and dying descent cgroups.

This data will be used later to add an ability to control cgroup
hierarchy (limit the depth and the number of descent cgroups)
and display hierarchy stats.

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Suggested-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: kernel-team@fb.com
Cc: cgroups@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
parent c705a00d

include/linux/cgroup-defs.h

+8 −0
Original line number Diff line number Diff line
@@ -273,6 +273,14 @@ struct cgroup { 
	 */

	int level;



	/*

	 * Keep track of total numbers of visible and dying descent cgroups.

	 * Dying cgroups are cgroups which were deleted by a user,

	 * but are still existing because someone else is holding a reference.

	 */

	int nr_descendants;

	int nr_dying_descendants;



	/*

	 * Each non-empty css_set associated with this cgroup contributes

	 * one to nr_populated_csets.  The counter is zero iff this cgroup

kernel/cgroup/cgroup.c

+17 −2
Original line number Diff line number Diff line
@@ -4408,9 +4408,15 @@ static void css_release_work_fn(struct work_struct *work) 
		if (ss->css_released)

			ss->css_released(css);

	} else {

		struct cgroup *tcgrp;



		/* cgroup release path */

		trace_cgroup_release(cgrp);



		for (tcgrp = cgroup_parent(cgrp); tcgrp;

		     tcgrp = cgroup_parent(tcgrp))

			tcgrp->nr_dying_descendants--;



		cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);

		cgrp->id = -1;
@@ -4609,9 +4615,13 @@ static struct cgroup *cgroup_create(struct cgroup *parent) 
	cgrp->root = root;

	cgrp->level = level;



	for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp))

	for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) {

		cgrp->ancestor_ids[tcgrp->level] = tcgrp->id;



		if (tcgrp != cgrp)

			tcgrp->nr_descendants++;

	}



	if (notify_on_release(parent))

		set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
@@ -4817,7 +4827,7 @@ static void kill_css(struct cgroup_subsys_state *css) 
static int cgroup_destroy_locked(struct cgroup *cgrp)

	__releases(&cgroup_mutex) __acquires(&cgroup_mutex)

{

	struct cgroup *parent = cgroup_parent(cgrp);

	struct cgroup *tcgrp, *parent = cgroup_parent(cgrp);

	struct cgroup_subsys_state *css;

	struct cgrp_cset_link *link;

	int ssid;
@@ -4865,6 +4875,11 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) 
	if (parent && cgroup_is_threaded(cgrp))

		parent->nr_threaded_children--;



	for (tcgrp = cgroup_parent(cgrp); tcgrp; tcgrp = cgroup_parent(tcgrp)) {

		tcgrp->nr_descendants--;

		tcgrp->nr_dying_descendants++;

	}



	cgroup1_check_for_release(cgroup_parent(cgrp));



	/* put the base reference */

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