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Commit 6cd0f5bb authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: separate out interface file creation from css creation 



Currently, interface files are created when a css is created depending
on whether @visible is set.  This patch separates out the two into
separate steps to help code refactoring and eventually allow cgroups
which aren't visible through cgroup fs.

Move css_populate_dir() out of create_css() and drop @visible.  While
at it, rename the function to css_create() for consistency.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarZefan Li <lizefan@huawei.com>
parent 20b454a6

kernel/cgroup.c

+43 −29
Original line number Diff line number Diff line
@@ -222,8 +222,8 @@ static struct cftype cgroup_legacy_base_files[]; 
static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);

static void css_task_iter_advance(struct css_task_iter *it);

static int cgroup_destroy_locked(struct cgroup *cgrp);

static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,

		      bool visible);

static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,

					      struct cgroup_subsys *ss);

static void css_release(struct percpu_ref *ref);

static void kill_css(struct cgroup_subsys_state *css);

static int cgroup_addrm_files(struct cgroup_subsys_state *css,
@@ -3082,15 +3082,27 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, 
	 */

	do_each_subsys_mask(ss, ssid, enable) {

		cgroup_for_each_live_child(child, cgrp) {

			if (css_enable & (1 << ssid))

				ret = create_css(child, ss,

					cgrp->subtree_control & (1 << ssid));

			else

			if (css_enable & (1 << ssid)) {

				struct cgroup_subsys_state *css;



				css = css_create(child, ss);

				if (IS_ERR(css)) {

					ret = PTR_ERR(css);

					goto err_undo_css;

				}



				if (cgrp->subtree_control & (1 << ssid)) {

					ret = css_populate_dir(css, NULL);

					if (ret)

						goto err_undo_css;

				}

			} else {

				ret = css_populate_dir(cgroup_css(child, ss),

						       NULL);

				if (ret)

					goto err_undo_css;

			}

		}

	} while_each_subsys_mask();



	/*
@@ -4717,7 +4729,9 @@ static void css_release_work_fn(struct work_struct *work) 
		 * Those are supported by RCU protecting clearing of

		 * cgrp->kn->priv backpointer.

		 */

		RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL);

		if (cgrp->kn)

			RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv,

					 NULL);

	}



	mutex_unlock(&cgroup_mutex);
@@ -4801,17 +4815,16 @@ static void offline_css(struct cgroup_subsys_state *css) 
}



/**

 * create_css - create a cgroup_subsys_state

 * css_create - create a cgroup_subsys_state

 * @cgrp: the cgroup new css will be associated with

 * @ss: the subsys of new css

 * @visible: whether to create control knobs for the new css or not

 *

 * Create a new css associated with @cgrp - @ss pair.  On success, the new

 * css is online and installed in @cgrp with all interface files created if

 * @visible.  Returns 0 on success, -errno on failure.

 * css is online and installed in @cgrp.  This function doesn't create the

 * interface files.  Returns 0 on success, -errno on failure.

 */

static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,

		      bool visible)

static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,

					      struct cgroup_subsys *ss)

{

	struct cgroup *parent = cgroup_parent(cgrp);

	struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
@@ -4822,7 +4835,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, 


	css = ss->css_alloc(parent_css);

	if (IS_ERR(css))

		return PTR_ERR(css);

		return css;



	init_and_link_css(css, ss, cgrp);
@@ -4835,12 +4848,6 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, 
		goto err_free_percpu_ref;

	css->id = err;



	if (visible) {

		err = css_populate_dir(css, NULL);

		if (err)

			goto err_free_id;

	}



	/* @css is ready to be brought online now, make it visible */

	list_add_tail_rcu(&css->sibling, &parent_css->children);

	cgroup_idr_replace(&ss->css_idr, css, css->id);
@@ -4858,18 +4865,16 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, 
		ss->warned_broken_hierarchy = true;

	}



	return 0;

	return css;



err_list_del:

	list_del_rcu(&css->sibling);

	css_clear_dir(css, NULL);

err_free_id:

	cgroup_idr_remove(&ss->css_idr, css->id);

err_free_percpu_ref:

	percpu_ref_exit(&css->refcnt);

err_free_css:

	call_rcu(&css->rcu_head, css_free_rcu_fn);

	return err;

	return ERR_PTR(err);

}



static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
@@ -4966,10 +4971,19 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, 


	/* let's create and online css's */

	do_each_subsys_mask(ss, ssid, parent->subtree_ss_mask) {

		ret = create_css(cgrp, ss,

				 parent->subtree_control & (1 << ssid));

		struct cgroup_subsys_state *css;



		css = css_create(cgrp, ss);

		if (IS_ERR(css)) {

			ret = PTR_ERR(css);

			goto out_destroy;

		}



		if (parent->subtree_control & (1 << ssid)) {

			ret = css_populate_dir(css, NULL);

			if (ret)

				goto out_destroy;

		}

	} while_each_subsys_mask();



	/*