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 <t...@kernel.org>
---
kernel/cgroup.c | 40 +++++++++++++++++++++++++---------------
1 file changed, 25 insertions(+), 15 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c5368c0..afc47d6 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -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);
--
1.7.11.7
--
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