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Commit b3bfd983 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: collapse cgroup_create() into croup_mkdir() 



cgroup_mkdir() is the sole user of cgroup_create().  Let's collapse
the latter into the former.  This will help simplifying locking.
While at it, remove now stale comment about inode locking.

This patch doesn't introduce any functional changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent ba0f4d76

kernel/cgroup.c

+13 −39
Original line number Diff line number Diff line
@@ -4235,30 +4235,24 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) 
	return err;

}



/**

 * cgroup_create - create a cgroup

 * @parent: cgroup that will be parent of the new cgroup

 * @name: name of the new cgroup

 * @mode: mode to set on new cgroup

 */

static long cgroup_create(struct cgroup *parent, const char *name,

static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,

			umode_t mode)

{

	struct cgroup *cgrp;

	struct cgroup *parent = parent_kn->priv, *cgrp;

	struct cgroup_root *root = parent->root;

	int ssid, ret;

	struct cgroup_subsys *ss;

	struct kernfs_node *kn;



	mutex_lock(&cgroup_tree_mutex);

	int ssid, ret;



	/*

	 * Only live parents can have children.  Note that the liveliness

	 * check isn't strictly necessary because cgroup_mkdir() and

	 * cgroup_rmdir() are fully synchronized by i_mutex; however, do it

	 * anyway so that locking is contained inside cgroup proper and we

	 * don't get nasty surprises if we ever grow another caller.

	 * cgroup_mkdir() grabs cgroup_tree_mutex which nests outside

	 * kernfs active_ref and cgroup_create() already synchronizes

	 * properly against removal through cgroup_lock_live_group().

	 * Break it before calling cgroup_create().

	 */

	cgroup_get(parent);

	kernfs_break_active_protection(parent_kn);

	mutex_lock(&cgroup_tree_mutex);

	if (!cgroup_lock_live_group(parent)) {

		ret = -ENODEV;

		goto out_unlock_tree;
@@ -4357,6 +4351,8 @@ static long cgroup_create(struct cgroup *parent, const char *name, 
	mutex_unlock(&cgroup_mutex);

out_unlock_tree:

	mutex_unlock(&cgroup_tree_mutex);

	kernfs_unbreak_active_protection(parent_kn);

	cgroup_put(parent);

	return ret;



out_destroy:
@@ -4364,28 +4360,6 @@ static long cgroup_create(struct cgroup *parent, const char *name, 
	goto out_unlock;

}



static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,

			umode_t mode)

{

	struct cgroup *parent = parent_kn->priv;

	int ret;



	/*

	 * cgroup_create() grabs cgroup_tree_mutex which nests outside

	 * kernfs active_ref and cgroup_create() already synchronizes

	 * properly against removal through cgroup_lock_live_group().

	 * Break it before calling cgroup_create().

	 */

	cgroup_get(parent);

	kernfs_break_active_protection(parent_kn);



	ret = cgroup_create(parent, name, mode);



	kernfs_unbreak_active_protection(parent_kn);

	cgroup_put(parent);

	return ret;

}



/*

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

 * css_tryget_online() is now guaranteed to fail.