cgroup: make ->pre_destroy() return void

All ->pre_destory() implementations return 0 now, which is the only
allowed return value.  Make it return void.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Vivek Goyal <vgoyal@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c5f6fb28dd0e..83cd7d041c62 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4054,7 +4054,7 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
         mutex_unlock(&cgroup_mutex);
         for_each_subsys(cgrp->root, ss)
                 if (ss->pre_destroy)
-                        WARN_ON_ONCE(ss->pre_destroy(cgrp));
+                        ss->pre_destroy(cgrp);
         mutex_lock(&cgroup_mutex);
 
         /*