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Date: Thu, 10 Nov 2011 19:12:17 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Pavel Emelyanov <xemul@parallels.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        Glauber Costa <glommer@parallels.com>, Nathan Lynch <ntl@pobox.com>,
        Tejun Heo <tj@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Serge Hallyn <serue@us.ibm.com>, Daniel Lezcano <dlezcano@fr.ibm.com>
Subject: Re: [PATCH 2/3] pids: Split alloc_pidmap into parts
Message-ID: <20111110181217.GA32156@redhat.com>
References: <4EBC0696.9030103@parallels.com> <4EBC06C5.4080805@parallels.com>
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On 11/10, Pavel Emelyanov wrote:
>
> The map's page allocation code is moved to separate function
> to make clone-with-pids patching simpler.

Sorry for the really cosmetic nit, but I simply can't resist...

> +static int alloc_pidmap_page(struct pidmap *map)
> +{
> +	void *page = kzalloc(PAGE_SIZE, GFP_KERNEL);
> +
> +	/*
> +	 * Free the page if someone raced with us
> +	 * installing it:
> +	 */
> +	spin_lock_irq(&pidmap_lock);
> +	if (!map->page) {
> +		map->page = page;
> +		page = NULL;
> +	}
> +	spin_unlock_irq(&pidmap_lock);
> +	kfree(page);
> +
> +	return map->page ? 0 : -1;

Again, I won't insist, but "return !map->page" looks more readable.
Even better (imho) would be to return map->page, and change the
single caller to check "if (!alloc_pidnap_page())".

Oleg.