linux-kernel - Re: [PATCH] xen/p2m: Check __brk

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Message-ID: <1343289182.8016.38.camel@dagon.hellion.org.uk>
Date:	Thu, 26 Jul 2012 08:53:02 +0100
From:	Ian Campbell <Ian.Campbell@...rix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com
Subject: Re: [PATCH] xen/p2m: Check __brk_limit before allocating.

On Tue, 2012-07-24 at 16:23 -0400, Konrad Rzeszutek Wilk wrote:
> diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
> index 64effdc..b5bb26c 100644
> --- a/arch/x86/xen/p2m.c
> +++ b/arch/x86/xen/p2m.c
> @@ -498,7 +498,14 @@ static bool alloc_p2m(unsigned long pfn)
>  
>  	return true;
>  }
> -
> +#include <asm/sections.h>
> +bool __init can_extend_brk()
> +{
> +	/* Always reserve one for the DMI extend_brk call. */

That seems a bit fragile, what if someone adds something else or the
link order changes etc?

Can't we just have a variant of extend_brk which returns NULL instead of
BUG_ON and do error checking?

Or even just change extend_brk and push the BUG_ONs out to the callers
-- there aren't that many of them.

Ian.
-- 
Ian Campbell

Most people in this society who aren't actively mad are, at best,
reformed or potential lunatics.
		-- Susan Sontag

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