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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Fri, 8 Oct 2021 14:37:12 +0200
Message-ID: <CAK8P3a2=X5tPppmcV4x9=pyodiPfoq=tA5jVKuMwA1nKJe=_bA@mail.gmail.com>
Subject: Re: [musl] Re: [alsa-devel] [PATCH v7 8/9] ALSA: add new 32-bit
 layout for snd_pcm_mmap_status/control
To:     musl@lists.openwall.com
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Michael Forney <mforney@mforney.org>,
        ALSA Development Mailing List <alsa-devel@alsa-project.org>,
        Takashi Iwai <tiwai@suse.com>,
        Baolin Wang <baolin.wang@linaro.org>,
        y2038 Mailman List <y2038@lists.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Mark Brown <broonie@kernel.org>,
        Baolin Wang <baolin.wang7@gmail.com>
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On Fri, Oct 8, 2021 at 2:06 PM Rich Felker <dalias@libc.org> wrote:
> On Fri, Oct 08, 2021 at 11:24:39AM +0200, Arnd Bergmann wrote:
> >
> > I've tried to understand this part of musl's convert_ioctl_struct(), but I just
> > can't figure out whether it does the conversion based the on the layout that
> > is currently used in the kernel, or based on the layout we should have been
> > using, and would use with the above fix. Rich, can you help me here?
>
> If the attempted 64-bit ioctl is missing (ENOTTY), it does the
> conversion to the legacy 32-bit one and retries with that, then
> converts the results back to the 64-bit form.

I understand that it tries to do that.

The part that I'm not sure about is which of the two possible
64-bit forms it's using -- the broken one we have defined in the
kernel headers, or the one we were trying to define but failed.

      Arnd