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>

5 files changed, 5 insertions, 9 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index f3b44a65fc7a..a7816f3d0059 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -600,7 +600,7 @@ struct cftype blkcg_files[] = {
  *
  * This is the blkcg counterpart of ioc_release_fn().
  */
-static int blkcg_pre_destroy(struct cgroup *cgroup)
+static void blkcg_pre_destroy(struct cgroup *cgroup)
 {
         struct blkcg *blkcg = cgroup_to_blkcg(cgroup);
 
@@ -622,7 +622,6 @@ static int blkcg_pre_destroy(struct cgroup *cgroup)
         }
 
         spin_unlock_irq(&blkcg->lock);
-        return 0;
 }
 
 static void blkcg_destroy(struct cgroup *cgroup)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 47868a86ba2b..adb2adc8ec1a 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -436,7 +436,7 @@ int cgroup_taskset_size(struct cgroup_taskset *tset);
 
 struct cgroup_subsys {
         struct cgroup_subsys_state *(*create)(struct cgroup *cgrp);
-        int (*pre_destroy)(struct cgroup *cgrp);
+        void (*pre_destroy)(struct cgroup *cgrp);
         void (*destroy)(struct cgroup *cgrp);
         int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
         void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
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);
 
         /*
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index dc595c6b1f55..0d3a1a317731 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -155,7 +155,7 @@ out:
  * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
  * the parent cgroup.
  */
-static int hugetlb_cgroup_pre_destroy(struct cgroup *cgroup)
+static void hugetlb_cgroup_pre_destroy(struct cgroup *cgroup)
 {
         struct hstate *h;
         struct page *page;
@@ -172,8 +172,6 @@ static int hugetlb_cgroup_pre_destroy(struct cgroup *cgroup)
                 }
                 cond_resched();
         } while (hugetlb_cgroup_have_usage(cgroup));
-
-        return 0;
 }
 
 int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6678f991c6c6..a1811ce60e20 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5002,12 +5002,11 @@ free_out:
         return ERR_PTR(error);
 }
 
-static int mem_cgroup_pre_destroy(struct cgroup *cont)
+static void mem_cgroup_pre_destroy(struct cgroup *cont)
 {
         struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
 
         mem_cgroup_reparent_charges(memcg);
-        return 0;
 }
 
 static void mem_cgroup_destroy(struct cgroup *cont)