linux-kernel - Re: [PATCH 12/21] dma-iommu: factor atomic pool allocations into helpers

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Message-ID: <83615173-a8b4-e0eb-bac3-1a58d61ea4ef@arm.com>
Date:   Thu, 18 Apr 2019 16:06:56 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Christoph Hellwig <hch@....de>
Cc:     Joerg Roedel <joro@...tes.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/21] dma-iommu: factor atomic pool allocations into
 helpers

On 17/04/2019 07:33, Christoph Hellwig wrote:
> On Wed, Apr 10, 2019 at 08:11:57AM +0200, Christoph Hellwig wrote:
>> On Tue, Apr 09, 2019 at 06:59:32PM +0100, Robin Murphy wrote:
>>> On 27/03/2019 08:04, Christoph Hellwig wrote:
>>>> This keeps the code together and will simplify compiling the code
>>>> out on architectures that are always dma coherent.
>>>
>>> And this is where things take a turn in the direction I just can't get on
>>> with - I'm looking at the final result and the twisty maze of little
>>> disjoint helpers all overlapping each other in functionality is really
>>> difficult to follow. And I would *much* rather have things rely on
>>> compile-time constant optimisation than spend the future having to fix the
>>> #ifdefed parts for arm64 whenever x86-centric changes fail to test them.
>>
>> Can you draft up a patch on top of my series to show me what you
>> want?  I can take care of finishing it up and moving the changes
>> into the right patches in the series.
> 
> Any chance to make some progress on this?  Or at least a better
> description of what you want?

OK, I'm still looking at mmap and get_sgtable, but for now I've pushed 
out a partial branch that consolidates alloc and free in a way which 
makes sense to me:

   git://linux-arm.org/linux-rm  dma/rework

Please let me know what you think.

Robin.