linux-kernel - Re: remove the ->mapping_error method from dma_map

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAHk-=wh=_T=A53+o4zLNbKio43LGqVDb0KCbWPDvAg54bRDmWw@mail.gmail.com>
Date:   Thu, 22 Nov 2018 08:50:47 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Christoph Hellwig <hch@....de>
Cc:     iommu@...ts.linux-foundation.org, jdmason@...zu.us,
        joro@...tes.org, David Woodhouse <dwmw2@...radead.org>,
        m.szyprowski@...sung.com, robin.murphy@....com,
        "the arch/x86 maintainers" <x86@...nel.org>,
        linux-alpha@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-ia64@...r.kernel.org, linux-parisc@...r.kernel.org,
        xen-devel@...ts.xenproject.org, linux-arch@...r.kernel.org,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>
Subject: Re: remove the ->mapping_error method from dma_map_ops V2

On Thu, Nov 22, 2018 at 6:03 AM Christoph Hellwig <hch@....de> 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