linux-kernel - Re: [PATCH] Introduce dmam_zalloc

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Message-ID: <20170809133705.GA25491@lst.de>
Date:   Wed, 9 Aug 2017 15:37:05 +0200
From:   Christoph Hellwig <hch@....de>
To:     Michael Moese <michael.moese@....de>
Cc:     Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Introduce dmam_zalloc_coherent()

On Tue, Aug 08, 2017 at 11:15:35AM +0200, Michael Moese wrote:
> All memory allocation functions have a pendant for allocating zeroed
> memory, but dmam_alloc_coherent does not have such a pendant.
> However, it is easier to read dmam_zalloc_coherent than passing an extra
> flag or, even worse, see memset() after the allocation.
> This patch adds an inline function dmam_zalloc_coherent(), exactly like
> the implementation of dma_zalloc_coherent().

I'm a bit worried about the __GFP_ZERO as we have lots of non-kmalloc
implementations of these.  But on the other hand we already implement
dma_zalloc_coherent the same way, which means we'd already buggy.

So I plan to apply this for 4.14, but I also plan to spend some time
to implement all the existin alloc ops to make sure it's going to work
fine.