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Commit 223dbc38 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: bounce cgroup_subsys_state ref kill confirmation to a work item 



css (cgroup_subsys_state) offlining, which requires process context,
will be moved to ref kill confirmation.  In preparation, bounce
css_killed handling through css->destroy_work.

css_ref_killed_fn() is renamed to css_killed_ref_fn() so that it's
consistent with the new css_killed_work_fn().

This patch adds an additional work item bouncing but doesn't change
the actual logic.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent ae7f164a

kernel/cgroup.c

+18 −3
Original line number Diff line number Diff line
@@ -4555,12 +4555,27 @@ static void cgroup_css_killed(struct cgroup *cgrp) 
	schedule_work(&cgrp->destroy_work);

}



static void css_ref_killed_fn(struct percpu_ref *ref)

/*

 * This is called when the refcnt of a css is confirmed to be killed.

 * css_tryget() is now guaranteed to fail.

 */

static void css_killed_work_fn(struct work_struct *work)

{

	struct cgroup_subsys_state *css =

		container_of(work, struct cgroup_subsys_state, destroy_work);

	struct cgroup *cgrp = css->cgroup;



	cgroup_css_killed(cgrp);

}



/* css kill confirmation processing requires process context, bounce */

static void css_killed_ref_fn(struct percpu_ref *ref)

{

	struct cgroup_subsys_state *css =

		container_of(ref, struct cgroup_subsys_state, refcnt);



	cgroup_css_killed(css->cgroup);

	INIT_WORK(&css->destroy_work, css_killed_work_fn);

	schedule_work(&css->destroy_work);

}



/**
@@ -4634,7 +4649,7 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) 
		percpu_ref_get(&css->refcnt);



		atomic_inc(&cgrp->css_kill_cnt);

		percpu_ref_kill_and_confirm(&css->refcnt, css_ref_killed_fn);

		percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);

	}

	cgroup_css_killed(cgrp);