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Commit 27f26753 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: replace css_set walking populated test with testing cgrp->nr_populated_csets 



Implement trivial cgroup_has_tasks() which tests whether
cgrp->nr_populated_csets is zero and replace the explicit local
populated test in cgroup_subtree_control().  This simplifies the code
and cgroup_has_tasks() will be used in more places later.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 788b950c

kernel/cgroup/cgroup.c

+8 −22
Original line number Diff line number Diff line
@@ -325,6 +325,11 @@ static struct cgroup *cgroup_parent(struct cgroup *cgrp) 
	return NULL;

}



static bool cgroup_has_tasks(struct cgroup *cgrp)

{

	return cgrp->nr_populated_csets;

}



/* subsystems visibly enabled on a cgroup */

static u16 cgroup_control(struct cgroup *cgrp)

{
@@ -2971,27 +2976,8 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
	 * Except for the root, subtree_control must be zero for a cgroup

	 * with tasks so that child cgroups don't compete against tasks.

	 */

	if (enable && cgroup_parent(cgrp)) {

		struct cgrp_cset_link *link;



		/*

		 * Because namespaces pin csets too, @cgrp->cset_links

		 * might not be empty even when @cgrp is empty.  Walk and

		 * verify each cset.

		 */

		spin_lock_irq(&css_set_lock);



		ret = 0;

		list_for_each_entry(link, &cgrp->cset_links, cset_link) {

			if (css_set_populated(link->cset)) {

	if (enable && cgroup_parent(cgrp) && cgroup_has_tasks(cgrp)) {

		ret = -EBUSY;

				break;

			}

		}



		spin_unlock_irq(&css_set_lock);



		if (ret)

		goto out_unlock;

	}