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Date: Tue, 6 Sep 2011 15:17:47 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Paul Menage <paul@paulmenage.org>,
        Li Zefan <lizf@cn.fujitsu.com>, Johannes Weiner <hannes@cmpxchg.org>,
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        Kay Sievers <kay.sievers@vrfy.org>, Tim Hockin <thockin@hockin.org>,
        Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 02/12] cgroups: New resource counter inheritance API
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On Tue,  6 Sep 2011 02:12:56 +0200
Frederic Weisbecker <fweisbec@gmail.com> wrote:

> +void res_counter_inherit(struct res_counter *counter, int member)
> +{
> +	struct res_counter *parent;
> +	unsigned long long val;
> +
> +	parent = counter->parent;
> +	if (parent) {
> +		val = res_counter_read_u64(parent, member);
> +		res_counter_write_u64(counter, member, val);
> +	}
> +}

What locking protects the read-modify-write?  If none, please fix,
otherwise please document it.

All of kernel/res_counter.c is charmingly undocumented.