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From: Li Zefan <lizefan@huawei.com>
To: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: linux-next list <linux-next@vger.kernel.org>, Tejun Heo <tj@kernel.org>
Subject: Re: [RFC PATCH next]cgroup: use css_get() in cgroup_create() to check CSS_ROOT
Date: Fri, 16 Aug 2013 18:16:18 +0800	[thread overview]
Message-ID: <520DFBF2.5050903@huawei.com> (raw)
In-Reply-To: <1376647034.2642.22.camel@ThinkPad-T5421>

On 2013/8/16 17:57, Li Zhong wrote:
> It seems that the root css doesn't have refcnt allocated(not needed?),
> and would cause the booting error attached.
> 
> This patch tries to use css_get() to not increase the refcnt if parent
> is root.
...
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 723194f..781f8cd 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -4485,7 +4485,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
>  		struct cgroup_subsys_state *css = css_ar[ss->subsys_id];
>  
>  		dget(dentry);
> -		percpu_ref_get(&css->parent->refcnt);
> +		css_get(css->parent);

We use css_put() to drop this refcnt, so it makes sense to use css_get()
for consistency.

Acked-by: Li Zefan <lizefan@huawei.com>

  reply	other threads:[~2013-08-16 10:16 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-16  9:57 [RFC PATCH next]cgroup: use css_get() in cgroup_create() to check CSS_ROOT Li Zhong
2013-08-16 10:16 ` Li Zefan [this message]
2013-08-16 14:58   ` Tejun Heo

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