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Commit 3c14f8b4 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: move subsys file removal to kill_css() 



With the planned unified hierarchy, individual css's will be created
and destroyed dynamically across the lifetime of a cgroup.  To enable
such usages, css destruction is being decoupled from cgroup
destruction.  This patch moves subsys file removal from
cgroup_destroy_locked() to kill_css().

While this changes the order of destruction operations, the changes
shouldn't be noticeable to cgroup subsystems or userland.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent edae0c33

kernel/cgroup.c

+9 −7
Original line number Diff line number Diff line
@@ -4599,13 +4599,15 @@ static void css_killed_ref_fn(struct percpu_ref *ref) 
 * kill_css - destroy a css

 * @css: css to destroy

 *

 * This function initiates destruction of @css by putting its base

 * reference.  ->css_offline() will be invoked asynchronously once

 * css_tryget() is guaranteed to fail and when the reference count reaches

 * zero, @css will be released.

 * This function initiates destruction of @css by removing cgroup interface

 * files and putting its base reference.  ->css_offline() will be invoked

 * asynchronously once css_tryget() is guaranteed to fail and when the

 * reference count reaches zero, @css will be released.

 */

static void kill_css(struct cgroup_subsys_state *css)

{

	cgroup_clear_dir(css->cgroup, 1 << css->ss->subsys_id);



	/*

	 * Killing would put the base ref, but we need to keep it alive

	 * until after ->css_offline().
@@ -4703,10 +4705,10 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) 
		cgroup_destroy_css_killed(cgrp);



	/*

	 * Clear and remove @cgrp directory.  The removal puts the base ref

	 * but we aren't quite done with @cgrp yet, so hold onto it.

	 * Clear the base files and remove @cgrp directory.  The removal

	 * puts the base ref but we aren't quite done with @cgrp yet, so

	 * hold onto it.

	 */

	cgroup_clear_dir(cgrp, cgrp->root->subsys_mask);

	cgroup_addrm_files(cgrp, cgroup_base_files, false);

	dget(d);

	cgroup_d_remove_dir(d);