Re: remove the ->mapping_error method from dma_map_ops V2
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- To: Christoph Hellwig <hch@xxxxxx>
- Subject: Re: remove the ->mapping_error method from dma_map_ops V2
- From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 22 Nov 2018 08:50:47 -0800
- Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx, jdmason@xxxxxxxx, joro@xxxxxxxxxx, David Woodhouse <dwmw2@xxxxxxxxxxxxx>, m.szyprowski@xxxxxxxxxxx, robin.murphy@xxxxxxx, "the arch/x86 maintainers" <x86@xxxxxxxxxx>, linux-alpha@xxxxxxxxxxxxxxx, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linux-ia64@xxxxxxxxxxxxxxx, linux-parisc@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, linux-arch@xxxxxxxxxxxxxxx, Linux List Kernel Mailing <linux-kernel@xxxxxxxxxxxxxxx>
- In-reply-to: <20181122140320.24080-1-hch@lst.de>
- References: <20181122140320.24080-1-hch@lst.de>
On Thu, Nov 22, 2018 at 6:03 AM Christoph Hellwig <hch@xxxxxx> wrote:
>
> The 0 return doesn't work for direct mappings that have ram at address
> zero and a lot of IOMMUs that start allocating bus space from address
> zero, so we can't consolidate on that, but I think we can move everyone
> to all-Fs, which the patch here does.
Hmm. Maybe not limit it to just all ones, but actually use the
(standard, for the kernel) IS_ERR_VALUE()?
That basically reserves the last 4095 values in an unsigned long for
error values.
Then those functions could actually return *what* error they
encountered, using just plain
return -ENOMEM;
or whatever?
Linus
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