linux-kernel - Re: [PATCH v2] dmaengine: rcar-dmac: don't use DMAC error interrupt

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: <CAMuHMdV-MoVnfJarHc9xZX_ZN7sHmKjGKxnhHyYUBof_P6R9ew@mail.gmail.com>
Date:   Wed, 13 Jun 2018 13:36:39 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
Cc:     vkoul@...nel.org, Dan Williams <dan.j.williams@...el.com>,
        Magnus Damm <magnus.damm@...il.com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Kieran Bingham <kieran@...uared.org.uk>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        dmaengine@...r.kernel.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2] dmaengine: rcar-dmac: don't use DMAC error interrupt

Hi Morimoto-san,

Thanks for your patch!

On Wed, Jun 13, 2018 at 10:49 AM Kuninori Morimoto
<kuninori.morimoto.gx@...esas.com> wrote:
> From: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
>
> Current rcar-dmac is using DMAC error interrupt which will handle all
> channel's error. But in this design, error handling itself will be
> issue if user want to use virtualization, multi OS, etc.
> This patch removes current DMAC error interrupt handling, and handle it
> on each channel interrupt handler.

Just wondering, what's the usage pattern where this causes a problem?
Do you plan to export part of a SYS-DMAC instance to a guest?
How to maintain host/guest isolation?

> --- a/Documentation/devicetree/bindings/dma/renesas,rcar-dmac.txt
> +++ b/Documentation/devicetree/bindings/dma/renesas,rcar-dmac.txt
> @@ -38,6 +38,7 @@ Required Properties:
>  - interrupt-names: one entry for the error interrupt, named "error", plus one
>    entry per channel, named "ch%u", where %u is the channel number ranging from
>    zero to the number of channels minus one.
> +  # "error" interrupt will be ignored, so far

Again, DT describes hardware, not software policy.
So please drop all changes to the bindings.

With that fixed:
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds