[PATCH v2] memcg: add mem_cgroup_from_css() helper

[PATCH v2] memcg: add mem_cgroup_from_css() helper

[Wanpeng Li]

Changelog v2:
* fix too many args to mem_cgroup_from_css() (spotted by Kirill A. Shutemov)
* fix kernel build failed (spotted by Fengguang)

Add a mem_cgroup_from_css() helper to replace open-coded invokations of
container_of().  To clarify the code and to add a little more type safety.

Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>

---
 mm/memcontrol.c |   19 +++++++++++--------
 1 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 883283d..f0c7639 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -407,6 +407,12 @@ enum charge_type {
 static void mem_cgroup_get(struct mem_cgroup *memcg);
 static void mem_cgroup_put(struct mem_cgroup *memcg);
 
+static inline 
+struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
+{
+	return container_of(s, struct mem_cgroup, css);
+}
+
 /* Writing them here to avoid exposing memcg's inner layout */
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
 #include <net/sock.h>
@@ -864,9 +870,8 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
 
 struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
 {
-	return container_of(cgroup_subsys_state(cont,
-				mem_cgroup_subsys_id), struct mem_cgroup,
-				css);
+	return mem_cgroup_from_css(cgroup_subsys_state(cont,
+				mem_cgroup_subsys_id));
 }
 
 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
@@ -879,8 +884,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 	if (unlikely(!p))
 		return NULL;
 
-	return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
-				struct mem_cgroup, css);
+	return mem_cgroup_from_css(task_subsys_state(p, mem_cgroup_subsys_id));
 }
 
 struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
@@ -966,8 +970,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 		css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id);
 		if (css) {
 			if (css == &root->css || css_tryget(css))
-				memcg = container_of(css,
-						     struct mem_cgroup, css);
+				memcg = mem_cgroup_from_css(css);
 		} else
 			id = 0;
 		rcu_read_unlock();
@@ -2429,7 +2432,7 @@ static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
 	css = css_lookup(&mem_cgroup_subsys, id);
 	if (!css)
 		return NULL;
-	return container_of(css, struct mem_cgroup, css);
+	return mem_cgroup_from_css(css);
 }
 
 struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
-- 
1.7.7.6

Re: [PATCH v2] memcg: add mem_cgroup_from_css() helper

[Wanpeng Li]

On Mon, Jul 23, 2012 at 10:08:56AM +0800, Gavin Shan wrote:
>
>For this case, we usually fix the build error on top of linux-next.
>It seems that you're changing the original patch and send again, which
>isn't reasonable, man :-)

OK, I will send a patch just fix build error against linux-next.

Regards,
Wanpeng Li

>
>Thanks,
>Gavin
>
>>Changelog v2:
>>* fix too many args to mem_cgroup_from_css() (spotted by Kirill A. Shutemov)
>>* fix kernel build failed (spotted by Fengguang)
>>
>>Add a mem_cgroup_from_css() helper to replace open-coded invokations of
>>container_of().  To clarify the code and to add a little more type safety.
>>
>>Acked-by: Michal Hocko <mhocko@suse.cz>
>>Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>>
>>---
>> mm/memcontrol.c |   19 +++++++++++--------
>> 1 files changed, 11 insertions(+), 8 deletions(-)
>>
>>diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>>index 883283d..f0c7639 100644
>>--- a/mm/memcontrol.c
>>+++ b/mm/memcontrol.c
>>@@ -407,6 +407,12 @@ enum charge_type {
>> static void mem_cgroup_get(struct mem_cgroup *memcg);
>> static void mem_cgroup_put(struct mem_cgroup *memcg);
>>
>>+static inline 
>>+struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
>>+{
>>+	return container_of(s, struct mem_cgroup, css);
>>+}
>>+
>> /* Writing them here to avoid exposing memcg's inner layout */
>> #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
>> #include <net/sock.h>
>>@@ -864,9 +870,8 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
>>
>> struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
>> {
>>-	return container_of(cgroup_subsys_state(cont,
>>-				mem_cgroup_subsys_id), struct mem_cgroup,
>>-				css);
>>+	return mem_cgroup_from_css(cgroup_subsys_state(cont,
>>+				mem_cgroup_subsys_id));
>> }
>>
>> struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
>>@@ -879,8 +884,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
>> 	if (unlikely(!p))
>> 		return NULL;
>>
>>-	return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
>>-				struct mem_cgroup, css);
>>+	return mem_cgroup_from_css(task_subsys_state(p, mem_cgroup_subsys_id));
>> }
>>
>> struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
>>@@ -966,8 +970,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
>> 		css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id);
>> 		if (css) {
>> 			if (css == &root->css || css_tryget(css))
>>-				memcg = container_of(css,
>>-						     struct mem_cgroup, css);
>>+				memcg = mem_cgroup_from_css(css);
>> 		} else
>> 			id = 0;
>> 		rcu_read_unlock();
>>@@ -2429,7 +2432,7 @@ static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
>> 	css = css_lookup(&mem_cgroup_subsys, id);
>> 	if (!css)
>> 		return NULL;
>>-	return container_of(css, struct mem_cgroup, css);
>>+	return mem_cgroup_from_css(css);
>> }
>>
>> struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
>>-- 
>>1.7.7.6
>>