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Commit c81c925a authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: factor out cgroup_subsys_state creation into create_css() 



Now that all opertations to create a css (cgroup_subsys_state) are
collected into a single loop in cgroup_create(), it's easy to factor
it out into its own function.  Factor out css creation into
create_css().  This makes the code easier to follow and will enable
decoupling css creation from cgroup creation which is necessary for
the planned unified hierarchy.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 9d403e99

kernel/cgroup.c

+57 −38
Original line number Diff line number Diff line
@@ -4073,6 +4073,62 @@ static void offline_css(struct cgroup_subsys_state *css) 
	RCU_INIT_POINTER(css->cgroup->subsys[ss->subsys_id], css);

}



/**

 * create_css - create a cgroup_subsys_state

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

 * @ss: the subsys of new css

 *

 * 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.

 * Returns 0 on success, -errno on failure.

 */

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

{

	struct cgroup *parent = cgrp->parent;

	struct cgroup_subsys_state *css;

	int err;



	lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);

	lockdep_assert_held(&cgroup_mutex);



	css = ss->css_alloc(cgroup_css(parent, ss));

	if (IS_ERR(css))

		return PTR_ERR(css);



	err = percpu_ref_init(&css->refcnt, css_release);

	if (err)

		goto err_free;



	init_css(css, ss, cgrp);



	err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id);

	if (err)

		goto err_free;



	err = online_css(css);

	if (err)

		goto err_free;



	dget(cgrp->dentry);

	css_get(css->parent);



	if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&

	    parent->parent) {

		pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",

			   current->comm, current->pid, ss->name);

		if (!strcmp(ss->name, "memory"))

			pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");

		ss->warned_broken_hierarchy = true;

	}



	return 0;



err_free:

	percpu_ref_cancel_init(&css->refcnt);

	ss->css_free(css);

	return err;

}



/*

 * cgroup_create - create a cgroup

 * @parent: cgroup that will be parent of the new cgroup
@@ -4084,7 +4140,6 @@ static void offline_css(struct cgroup_subsys_state *css) 
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,

			     umode_t mode)

{

	struct cgroup_subsys_state *css = NULL;

	struct cgroup *cgrp;

	struct cgroup_name *name;

	struct cgroupfs_root *root = parent->root;
@@ -4175,41 +4230,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 


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

	for_each_root_subsys(root, ss) {

		css = ss->css_alloc(cgroup_css(parent, ss));

		if (IS_ERR(css)) {

			err = PTR_ERR(css);

			css = NULL;

			goto err_destroy;

		}



		err = percpu_ref_init(&css->refcnt, css_release);

		if (err)

			goto err_destroy;



		init_css(css, ss, cgrp);



		err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id);

		if (err)

			goto err_destroy;



		err = online_css(css);

		err = create_css(cgrp, ss);

		if (err)

			goto err_destroy;



		dget(dentry);

		css_get(css->parent);



		/* mark it consumed for error path */

		css = NULL;



		if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&

		    parent->parent) {

			pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",

				   current->comm, current->pid, ss->name);

			if (!strcmp(ss->name, "memory"))

				pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");

			ss->warned_broken_hierarchy = true;

		}

	}



	mutex_unlock(&cgroup_mutex);
@@ -4230,10 +4253,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 
	return err;



err_destroy:

	if (css) {

		percpu_ref_cancel_init(&css->refcnt);

		css->ss->css_free(css);

	}

	cgroup_destroy_locked(cgrp);

	mutex_unlock(&cgroup_mutex);

	mutex_unlock(&dentry->d_inode->i_mutex);