linux-kernel - Re: Generic DMA

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Date:	Wed, 20 Jan 2010 12:00:31 +0100
From:	Joerg Roedel <joerg.roedel@....com>
To:	monstr@...str.eu, linux-kernel@...r.kernel.org,
	michal.simek@...alogix.com, arnd@...db.de,
	linux-arch@...r.kernel.org, fujita.tomonori@....ntt.co.jp,
	akpm@...ux-foundation.org, mingo@...e.hu
Subject: Re: Generic DMA - BUG_ON

On Wed, Jan 20, 2010 at 10:53:50AM +0000, Russell King wrote:
> and ops is NULL, then this code will oops; you will get a full register
> dump and backtrace.  You can use this information along with markup_oops.pl
> to find out where the problem is.

You can't rely on the oops if the code runs in process context. The
process may have address 0 mapped which would result in a security hole.
We had two of these bugs last year.

But I don't see any point in checking for dma_ops != NULL too. Any
developer would mention such a bug long before init is started.

	Joerg


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