cgroup: fix error return value in cgroup_mount()

commit eb46bf89696972b856a9adb6aebd5c7b65c266e4 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index bc1dcabe92176636baf79c7ef52e597422aeaf75..46ba3ebeed4d332de7ea275d56183ab5f72ed840 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1580,10 +1580,10 @@ 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;