cgroup: fix error return value in cgroup_mount()

When cgroup_mount() fails to allocate an id for the root, it didn't
set ret before jumping to unlock_drop ending up returning 0 after a
failure.  Fix it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org

1 files changed, 3 insertions, 3 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index aa95591c1430..793f37176077 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1566,10 +1566,10 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
                 mutex_lock(&cgroup_mutex);
                 mutex_lock(&cgroup_root_mutex);
 
-                root_cgrp->id = idr_alloc(&root->cgroup_idr, root_cgrp,
-                                           0, 1, GFP_KERNEL);
-                if (root_cgrp->id < 0)
+                ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL);
+                if (ret < 0)
                         goto unlock_drop;
+                root_cgrp->id = ret;
 
                 /* Check for name clashes with existing mounts */
                 ret = -EBUSY;