linux-kernel - Re: [PATCH kernel v8 21/31] powerpc/iommu: Split iommu_free

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Message-ID: <20150420025134.GG10218@voom>
Date:	Mon, 20 Apr 2015 12:51:34 +1000
From:	David Gibson <david@...son.dropbear.id.au>
To:	Alexey Kardashevskiy <aik@...abs.ru>
Cc:	linuxppc-dev@...ts.ozlabs.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH kernel v8 21/31] powerpc/iommu: Split iommu_free_table
 into 2 helpers

On Fri, Apr 17, 2015 at 02:29:23AM +1000, Alexey Kardashevskiy wrote:
> On 04/16/2015 04:46 PM, David Gibson wrote:
> >On Fri, Apr 10, 2015 at 04:31:03PM +1000, Alexey Kardashevskiy wrote:
> >>The iommu_free_table helper release memory it is using (the TCE table and
> >>@it_map) and release the iommu_table struct as well. We might not want
> >>the very last step as we store iommu_table in parent structures.
> >
> >Yeah, as I commented on the earlier patch, freeing the surrounding
> >group from a function taking just the individual table is wrong.
> 
> 
> This is iommu tables created by the old code which stores these iommu_table
> struct pointers in device nodes. I believe there is a plan to get rid of
> iommu tables there and when this is done, this workaround will be
> gone.

Um.. what?  The connection of where pointers are stored to an
obvious error with object lifetime handling is not at all obvious.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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