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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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2012-11-19 08:13:37 -08:00
parent 02ae7486d0
commit 42809dd422
1 changed files with 25 additions and 15 deletions
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40
kernel/cgroup.c
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@ -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);