memcg: add mem_cgroup_disabled()

We check mem_cgroup is disabled or not by checking
mem_cgroup_subsys.disabled.  I think it has more references than expected,
now.

replacing
   if (mem_cgroup_subsys.disabled)
with
   if (mem_cgroup_disabled())

give us good look, I think.

[kamezawa.hiroyu@jp.fujitsu.com: fix typo]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 30 insertions, 17 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 32c07b1852d6..472efd09118c 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -19,7 +19,7 @@
 
 #ifndef _LINUX_MEMCONTROL_H
 #define _LINUX_MEMCONTROL_H
-
+#include <linux/cgroup.h>
 struct mem_cgroup;
 struct page_cgroup;
 struct page;
@@ -87,6 +87,14 @@ extern long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 extern int do_swap_account;
 #endif
+
+static inline bool mem_cgroup_disabled(void)
+{
+        if (mem_cgroup_subsys.disabled)
+                return true;
+        return false;
+}
+
 #else /* CONFIG_CGROUP_MEM_RES_CTLR */
 struct mem_cgroup;
 
@@ -214,6 +222,11 @@ static inline long mem_cgroup_calc_reclaim(struct mem_cgroup *mem,
 {
         return 0;
 }
+
+static inline bool mem_cgroup_disabled(void)
+{
+        return true;
+}
 #endif /* CONFIG_CGROUP_MEM_CONT */
 
 #endif /* _LINUX_MEMCONTROL_H */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8ce4e9e47959..9846f617115d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -279,7 +279,7 @@ void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru)
         struct mem_cgroup *mem;
         struct mem_cgroup_per_zone *mz;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return;
         pc = lookup_page_cgroup(page);
         /* can happen while we handle swapcache. */
@@ -302,7 +302,7 @@ void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
         struct mem_cgroup_per_zone *mz;
         struct page_cgroup *pc;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return;
 
         pc = lookup_page_cgroup(page);
@@ -319,7 +319,7 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
         struct page_cgroup *pc;
         struct mem_cgroup_per_zone *mz;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return;
         pc = lookup_page_cgroup(page);
         /* barrier to sync with "charge" */
@@ -344,7 +344,7 @@ static void mem_cgroup_lru_fixup(struct page *page)
 void mem_cgroup_move_lists(struct page *page,
                            enum lru_list from, enum lru_list to)
 {
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return;
         mem_cgroup_del_lru_list(page, from);
         mem_cgroup_add_lru_list(page, to);
@@ -731,7 +731,7 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
 int mem_cgroup_newpage_charge(struct page *page,
                               struct mm_struct *mm, gfp_t gfp_mask)
 {
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return 0;
         if (PageCompound(page))
                 return 0;
@@ -753,7 +753,7 @@ int mem_cgroup_newpage_charge(struct page *page,
 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                                 gfp_t gfp_mask)
 {
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return 0;
         if (PageCompound(page))
                 return 0;
@@ -799,7 +799,7 @@ int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
         struct mem_cgroup *mem;
         swp_entry_t     ent;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return 0;
 
         if (!do_swap_account)
@@ -833,7 +833,7 @@ int mem_cgroup_cache_charge_swapin(struct page *page,
 {
         int ret = 0;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return 0;
         if (unlikely(!mm))
                 mm = &init_mm;
@@ -880,7 +880,7 @@ void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
 {
         struct page_cgroup *pc;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return;
         if (!ptr)
                 return;
@@ -909,7 +909,7 @@ void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
 
 void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
 {
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return;
         if (!mem)
                 return;
@@ -930,7 +930,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
         struct mem_cgroup *mem = NULL;
         struct mem_cgroup_per_zone *mz;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return NULL;
 
         if (PageSwapCache(page))
@@ -1049,7 +1049,7 @@ int mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr)
         struct mem_cgroup *mem = NULL;
         int ret = 0;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return 0;
 
         pc = lookup_page_cgroup(page);
@@ -1131,7 +1131,7 @@ int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
         int progress = 0;
         int retry = MEM_CGROUP_RECLAIM_RETRIES;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return 0;
         if (!mm)
                 return 0;
@@ -1697,7 +1697,7 @@ static void mem_cgroup_put(struct mem_cgroup *mem)
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 static void __init enable_swap_cgroup(void)
 {
-        if (!mem_cgroup_subsys.disabled && really_do_swap_account)
+        if (!mem_cgroup_disabled() && really_do_swap_account)
                 do_swap_account = 1;
 }
 #else
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 74ae8e01d071..7006a11350c8 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -74,7 +74,7 @@ void __init page_cgroup_init(void)
 
         int nid, fail;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return;
 
         for_each_online_node(nid)  {
@@ -247,7 +247,7 @@ void __init page_cgroup_init(void)
         unsigned long pfn;
         int fail = 0;
 
-        if (mem_cgroup_subsys.disabled)
+        if (mem_cgroup_disabled())
                 return;
 
         for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {