From: Roman Gushchin <guro@fb.com>
Date: Fri, 17 Aug 2018 22:46:36 +0000 (-0700)
Subject: mm: introduce mem_cgroup_put() helper
X-Git-Tag: v4.19~375^2~56
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=dc0b58643aff8b378086f25cce6789ccba68cbcb;p=platform%2Fkernel%2Flinux-rpi3.git

mm: introduce mem_cgroup_put() helper

Introduce the mem_cgroup_put() helper, which helps to eliminate guarding
memcg css release with "#ifdef CONFIG_MEMCG" in multiple places.

Link: http://lkml.kernel.org/r/20180623000600.5818-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 680d339..42f4719 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -378,6 +378,11 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
 	return css ? container_of(css, struct mem_cgroup, css) : NULL;
 }
 
+static inline void mem_cgroup_put(struct mem_cgroup *memcg)
+{
+	css_put(&memcg->css);
+}
+
 #define mem_cgroup_from_counter(counter, member)	\
 	container_of(counter, struct mem_cgroup, member)
 
@@ -850,6 +855,10 @@ static inline bool task_in_mem_cgroup(struct task_struct *task,
 	return true;
 }
 
+static inline void mem_cgroup_put(struct mem_cgroup *memcg)
+{
+}
+
 static inline struct mem_cgroup *
 mem_cgroup_iter(struct mem_cgroup *root,
 		struct mem_cgroup *prev,