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Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions

From Logan Gunthorpe <logang@deltatee.com>
Newsgroups linux.kernel
Subject Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions
Date 2017-04-27 17:50 +0200
Message-ID <tATQ6-2Ak-17@gated-at.bofh.it> (permalink)
References <tAdnP-8d5-5@gated-at.bofh.it> <tAdnQ-8d5-41@gated-at.bofh.it> <tApS2-7Eb-19@gated-at.bofh.it> <tABJw-7at-5@gated-at.bofh.it> <tALzb-5ht-1@gated-at.bofh.it>
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On 27/04/17 12:53 AM, Christoph Hellwig wrote:
> I think you'll need to follow the existing kmap semantics and never
> fail the iomem version either.  Otherwise you'll have a special case
> that's almost never used that has a different error path.
>
> Again, wrong way.  Suddenly making things fail for your special case
> that normally don't fail is a receipe for bugs.

I don't disagree but these restrictions make the problem impossible to
solve? If there is iomem behind a page in an SGL and someone tries to
map it, we either have to fail or we break iomem safety which was your
original concern.

Logan

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Thread

[PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Logan Gunthorpe <logang@deltatee.com> - 2017-04-25 20:30 +0200
  Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Christoph Hellwig <hch@lst.de> - 2017-04-26 09:50 +0200
    Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Logan Gunthorpe <logang@deltatee.com> - 2017-04-26 22:30 +0200
      Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Christoph Hellwig <hch@lst.de> - 2017-04-27 09:00 +0200
        Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-04-27 17:30 +0200
          Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Logan Gunthorpe <logang@deltatee.com> - 2017-04-27 18:00 +0200
        Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Logan Gunthorpe <logang@deltatee.com> - 2017-04-27 17:50 +0200
    Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Logan Gunthorpe <logang@deltatee.com> - 2017-04-27 22:20 +0200
  Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Logan Gunthorpe <logang@deltatee.com> - 2017-04-27 01:40 +0200

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