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Date: Tue, 20 Dec 2011 15:35:02 -0800
From: Tejun Heo <tj@kernel.org>
To: Mandeep Singh Baines <msb@chromium.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>, LKML <linux-kernel@vger.kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        containers@lists.linux-foundation.org, cgroups@vger.kernel.org,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Oleg Nesterov <oleg@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Paul Menage <paul@paulmenage.org>
Subject: Re: [PATCH 5/5] cgroup: separate out cgroup_attach_proc error
 handling code
Message-ID: <20111220233502.GN10752@google.com>
References: <1324422873-31001-1-git-send-email-msb@chromium.org>
 <1324422873-31001-6-git-send-email-msb@chromium.org>
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Hello,

On Tue, Dec 20, 2011 at 03:14:33PM -0800, Mandeep Singh Baines wrote:
> @@ -2067,9 +2067,10 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
>  	read_unlock(&tasklist_lock);
>  
>  	/* methods shouldn't be called if no task is actually migrating */
> -	retval = 0;
> -	if (!group_size)
> +	if (!group_size) {
> +		retval = 0;
>  		goto out_free_group_list;
> +	}

Eh... I don't think this is an improvement.  It's just different.

> @@ -2126,20 +2127,20 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
>  	 */
>  	synchronize_rcu();
>  	cgroup_wakeup_rmdir_waiter(cgrp);
> -	retval = 0;
> +	flex_array_free(group);
> +	return 0;

Hmm... maybe goto out_free_group_list?  Duplicating cleanup on success
and failure paths can lead future updaters forget one of them.  The
exit path in this function isn't pretty but I don't think the proposed
patch improves it either.

Thanks.

-- 
tejun