[RFC][PATCH 3/4] memcg: add accessor to mem_cgroup.css

[Wu Fengguang <fengguang.wu@intel.com>]

[-- Attachment #1: memcg-mem_cgroup_css.patch --]
[-- Type: text/plain, Size: 1511 bytes --]

So that one can check its cgroup id and free the reference count
grabbed by try_get_mem_cgroup_from_page().

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 include/linux/memcontrol.h |    7 +++++++
 mm/memcontrol.c            |    6 ++++++
 2 files changed, 13 insertions(+)

--- linux-mm.orig/include/linux/memcontrol.h	2009-08-31 15:25:48.000000000 +0800
+++ linux-mm/include/linux/memcontrol.h	2009-08-31 15:27:00.000000000 +0800
@@ -81,6 +81,8 @@ int mm_match_cgroup(const struct mm_stru
 	return cgroup == mem;
 }
 
+extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem);
+
 extern int
 mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr);
 extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
@@ -206,6 +208,11 @@ static inline int task_in_mem_cgroup(str
 	return 1;
 }
 
+static inline struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
+{
+	return NULL;
+}
+
 static inline int
 mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr)
 {
--- linux-mm.orig/mm/memcontrol.c	2009-08-31 15:25:48.000000000 +0800
+++ linux-mm/mm/memcontrol.c	2009-08-31 15:25:52.000000000 +0800
@@ -282,6 +282,12 @@ mem_cgroup_zoneinfo(struct mem_cgroup *m
 	return &mem->info.nodeinfo[nid]->zoneinfo[zid];
 }
 
+struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *mem)
+{
+	return &mem->css;
+}
+EXPORT_SYMBOL(mem_cgroup_css);
+
 static struct mem_cgroup_per_zone *
 page_cgroup_zoneinfo(struct page_cgroup *pc)
 {

--