[PATCH] hugetlb/cgroup: Remove unnecessary NULL checks

[PATCH] hugetlb/cgroup: Remove unnecessary NULL checks

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

cgroup_subsys_state can never be NULL, so don't check
for that in hugetlb_cgroup_from_css. Also current task will
always be part of some cgroup. So hugetlb_cgrop_from_task
cannot return NULL.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/hugetlb_cgroup.c |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index db40669..b834e8d 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -36,9 +36,7 @@ static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
 static inline
 struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
 {
-	if (s)
-		return container_of(s, struct hugetlb_cgroup, css);
-	return NULL;
+	return container_of(s, struct hugetlb_cgroup, css);
 }
 
 static inline
@@ -202,9 +200,6 @@ int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
 again:
 	rcu_read_lock();
 	h_cg = hugetlb_cgroup_from_task(current);
-	if (!h_cg)
-		h_cg = root_h_cgroup;
-
 	if (!css_tryget(&h_cg->css)) {
 		rcu_read_unlock();
 		goto again;
-- 
1.7.10

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Re: [PATCH] hugetlb/cgroup: Remove unnecessary NULL checks

[Michal Hocko]

On Sun 24-06-12 22:15:13, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> 
> cgroup_subsys_state can never be NULL, so don't check
> for that in hugetlb_cgroup_from_css. Also current task will
> always be part of some cgroup. So hugetlb_cgrop_from_task
> cannot return NULL.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Reviewed-by: Michal Hocko <mhocko@suse.cz>

> ---
>  mm/hugetlb_cgroup.c |    7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index db40669..b834e8d 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -36,9 +36,7 @@ static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
>  static inline
>  struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
>  {
> -	if (s)
> -		return container_of(s, struct hugetlb_cgroup, css);
> -	return NULL;
> +	return container_of(s, struct hugetlb_cgroup, css);
>  }
>  
>  static inline
> @@ -202,9 +200,6 @@ int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
>  again:
>  	rcu_read_lock();
>  	h_cg = hugetlb_cgroup_from_task(current);
> -	if (!h_cg)
> -		h_cg = root_h_cgroup;
> -
>  	if (!css_tryget(&h_cg->css)) {
>  		rcu_read_unlock();
>  		goto again;
> -- 
> 1.7.10
> 

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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