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Commit 42809dd4 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: separate out cgroup_destroy_locked() 



Separate out cgroup_destroy_locked() from cgroup_destroy().  This will
be later used in cgroup_create() failure path.

While at it, add lockdep asserts on i_mutex and cgroup_mutex, and move
@d and @parent assignments to their declarations.

This patch doesn't introduce any functional difference.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 02ae7486

kernel/cgroup.c

+25 −15
Original line number Diff line number Diff line
@@ -242,6 +242,8 @@ static DEFINE_SPINLOCK(hierarchy_id_lock); 
 */

static int need_forkexit_callback __read_mostly;



static int cgroup_destroy_locked(struct cgroup *cgrp);



#ifdef CONFIG_PROVE_LOCKING

int cgroup_lock_is_held(void)

{
@@ -4209,22 +4211,20 @@ static int cgroup_has_css_refs(struct cgroup *cgrp) 
	return 0;

}



static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)

static int cgroup_destroy_locked(struct cgroup *cgrp)

	__releases(&cgroup_mutex) __acquires(&cgroup_mutex)

{

	struct cgroup *cgrp = dentry->d_fsdata;

	struct dentry *d;

	struct cgroup *parent;

	struct dentry *d = cgrp->dentry;

	struct cgroup *parent = cgrp->parent;

	DEFINE_WAIT(wait);

	struct cgroup_event *event, *tmp;

	struct cgroup_subsys *ss;



	/* the vfs holds both inode->i_mutex already */

	mutex_lock(&cgroup_mutex);

	parent = cgrp->parent;

	if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) {

		mutex_unlock(&cgroup_mutex);

	lockdep_assert_held(&d->d_inode->i_mutex);

	lockdep_assert_held(&cgroup_mutex);



	if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children))

		return -EBUSY;

	}



	/*

	 * Block new css_tryget() by deactivating refcnt and mark @cgrp
@@ -4243,7 +4243,9 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) 
	/*

	 * Tell subsystems to initate destruction.  pre_destroy() should be

	 * called with cgroup_mutex unlocked.  See 3fa59dfbc3 ("cgroup: fix

	 * potential deadlock in pre_destroy") for details.

	 * potential deadlock in pre_destroy") for details.  This temporary

	 * unlocking should go away once cgroup_mutex is unexported from

	 * controllers.

	 */

	mutex_unlock(&cgroup_mutex);

	for_each_subsys(cgrp->root, ss)
@@ -4268,11 +4270,9 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) 


	/* delete this cgroup from parent->children */

	list_del_rcu(&cgrp->sibling);



	list_del_init(&cgrp->allcg_node);



	d = dget(cgrp->dentry);



	dget(d);

	cgroup_d_remove_dir(d);

	dput(d);
@@ -4293,10 +4293,20 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) 
	}

	spin_unlock(&cgrp->event_list_lock);



	mutex_unlock(&cgroup_mutex);

	return 0;

}



static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)

{

	int ret;



	mutex_lock(&cgroup_mutex);

	ret = cgroup_destroy_locked(dentry->d_fsdata);

	mutex_unlock(&cgroup_mutex);



	return ret;

}



static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss)

{

	INIT_LIST_HEAD(&ss->cftsets);