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Commit 35ef10da authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: rename cgroup_subsys_state->dput_work and its callback function 



css (cgroup_subsys_state) will become RCU protected and there will be
two stages which require punting to work item during release.  To
prepare for using the work item for multiple times, rename
css->dput_work to css->destroy_work and css_dput_fn() to
css_free_work_fn() and move work item initialization from css init to
right before the actual usage.

This reorganization doesn't introduce any behavior change.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 40e93b39

include/linux/cgroup.h

+1 −1
Original line number Diff line number Diff line
@@ -80,7 +80,7 @@ struct cgroup_subsys_state { 
	struct css_id __rcu *id;



	/* Used to put @cgroup->dentry on the last css_put() */

	struct work_struct dput_work;

	struct work_struct destroy_work;

};



/* bits in struct cgroup_subsys_state flags field */

kernel/cgroup.c

+10 −11
Original line number Diff line number Diff line
@@ -4259,10 +4259,10 @@ err: 
	return ret;

}



static void css_dput_fn(struct work_struct *work)

static void css_free_work_fn(struct work_struct *work)

{

	struct cgroup_subsys_state *css =

		container_of(work, struct cgroup_subsys_state, dput_work);

		container_of(work, struct cgroup_subsys_state, destroy_work);



	cgroup_dput(css->cgroup);

}
@@ -4272,7 +4272,14 @@ static void css_release(struct percpu_ref *ref) 
	struct cgroup_subsys_state *css =

		container_of(ref, struct cgroup_subsys_state, refcnt);



	schedule_work(&css->dput_work);

	/*

	 * css holds an extra ref to @cgrp->dentry which is put on the last

	 * css_put().  dput() requires process context, which css_put() may

	 * be called without.  @css->destroy_work will be used to invoke

	 * dput() asynchronously from css_put().

	 */

	INIT_WORK(&css->destroy_work, css_free_work_fn);

	schedule_work(&css->destroy_work);

}



static void init_cgroup_css(struct cgroup_subsys_state *css,
@@ -4287,14 +4294,6 @@ static void init_cgroup_css(struct cgroup_subsys_state *css, 
		css->flags |= CSS_ROOT;

	BUG_ON(cgroup_css(cgrp, ss->subsys_id));

	cgrp->subsys[ss->subsys_id] = css;



	/*

	 * css holds an extra ref to @cgrp->dentry which is put on the last

	 * css_put().  dput() requires process context, which css_put() may

	 * be called without.  @css->dput_work will be used to invoke

	 * dput() asynchronously from css_put().

	 */

	INIT_WORK(&css->dput_work, css_dput_fn);

}



/* invoke ->css_online() on a new CSS and mark it online if successful */