cgroup: reorganize cgroup_create()
Reorganize cgroup_create() so that all paths share unlock out path.
* All err_* labels are renamed to out_* as they're now shared by both
success and failure paths.
* @err renamed to @ret for the similar reason as above and so that
it's more consistent with other functions.
* cgroup memory allocation moved after locking so that freeing failed
cgroup happens before unlocking. While this moves more code inside
critical section, memory allocations inside cgroup locking are
already pretty common and this is unlikely to make any noticeable
difference.
* While at it, replace a stray @parent->root dereference with @root.
This reorganization will help simplifying locking.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 94d259b..1d6106c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4246,15 +4246,10 @@
{
struct cgroup *cgrp;
struct cgroup_root *root = parent->root;
- int ssid, err;
+ int ssid, ret;
struct cgroup_subsys *ss;
struct kernfs_node *kn;
- /* allocate the cgroup and its ID, 0 is reserved for the root */
- cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
- if (!cgrp)
- return -ENOMEM;
-
mutex_lock(&cgroup_tree_mutex);
/*
@@ -4265,8 +4260,15 @@
* don't get nasty surprises if we ever grow another caller.
*/
if (!cgroup_lock_live_group(parent)) {
- err = -ENODEV;
- goto err_unlock_tree;
+ ret = -ENODEV;
+ goto out_unlock_tree;
+ }
+
+ /* allocate the cgroup and its ID, 0 is reserved for the root */
+ cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL);
+ if (!cgrp) {
+ ret = -ENOMEM;
+ goto out_unlock;
}
/*
@@ -4275,15 +4277,15 @@
*/
cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_NOWAIT);
if (cgrp->id < 0) {
- err = -ENOMEM;
- goto err_unlock;
+ ret = -ENOMEM;
+ goto out_free_cgrp;
}
init_cgroup_housekeeping(cgrp);
cgrp->parent = parent;
cgrp->dummy_css.parent = &parent->dummy_css;
- cgrp->root = parent->root;
+ cgrp->root = root;
if (notify_on_release(parent))
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
@@ -4294,8 +4296,8 @@
/* create the directory */
kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
if (IS_ERR(kn)) {
- err = PTR_ERR(kn);
- goto err_free_id;
+ ret = PTR_ERR(kn);
+ goto out_free_id;
}
cgrp->kn = kn;
@@ -4318,20 +4320,20 @@
*/
cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
- err = cgroup_kn_set_ugid(kn);
- if (err)
- goto err_destroy;
+ ret = cgroup_kn_set_ugid(kn);
+ if (ret)
+ goto out_destroy;
- err = cgroup_addrm_files(cgrp, cgroup_base_files, true);
- if (err)
- goto err_destroy;
+ ret = cgroup_addrm_files(cgrp, cgroup_base_files, true);
+ if (ret)
+ goto out_destroy;
/* let's create and online css's */
for_each_subsys(ss, ssid) {
if (parent->child_subsys_mask & (1 << ssid)) {
- err = create_css(cgrp, ss);
- if (err)
- goto err_destroy;
+ ret = create_css(cgrp, ss);
+ if (ret)
+ goto out_destroy;
}
}
@@ -4344,25 +4346,22 @@
kernfs_activate(kn);
- mutex_unlock(&cgroup_mutex);
- mutex_unlock(&cgroup_tree_mutex);
+ ret = 0;
+ goto out_unlock;
- return 0;
-
-err_free_id:
+out_free_id:
cgroup_idr_remove(&root->cgroup_idr, cgrp->id);
-err_unlock:
- mutex_unlock(&cgroup_mutex);
-err_unlock_tree:
- mutex_unlock(&cgroup_tree_mutex);
+out_free_cgrp:
kfree(cgrp);
- return err;
-
-err_destroy:
- cgroup_destroy_locked(cgrp);
+out_unlock:
mutex_unlock(&cgroup_mutex);
+out_unlock_tree:
mutex_unlock(&cgroup_tree_mutex);
- return err;
+ return ret;
+
+out_destroy:
+ cgroup_destroy_locked(cgrp);
+ goto out_unlock;
}
static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,