linux-kernel - Re: [PATCH v2] iio: core: register chardev only if needed

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Message-ID: <CA+U=DspEg=XpOUKqtammKqOoLXoXEDKWQHqSauM1xna_Y+eqjA@mail.gmail.com>
Date:   Wed, 9 Dec 2020 17:55:22 +0200
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Alexandru Ardelean <alexandru.ardelean@...log.com>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>
Subject: Re: [PATCH v2] iio: core: register chardev only if needed

On Wed, Dec 9, 2020 at 5:53 PM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Wed, Dec 9, 2020 at 5:45 PM Alexandru Ardelean
> <ardeleanalex@...il.com> wrote:
> > On Wed, Dec 9, 2020 at 5:37 PM Andy Shevchenko
> > <andy.shevchenko@...il.com> wrote:
> > > On Thu, Dec 3, 2020 at 11:55 AM Alexandru Ardelean
> > > <alexandru.ardelean@...log.com> wrote:
>
> ...
>
> > > Are you sure there is no user space application that doesn't rely on
> > > character device to be always present?
> >
> > Nope.
> > I'm not sure.
> > I'm also not completely sure how Jonathan feels about this patch being
> > added now [so late].
> >
> > Though, technically if the chardev was already there, without all the
> > control in place [to enable IIO buffers and other stuff through the
> > chardev] then it's technically just a "marker" file.
> > Which arguably is a lot to have (i.e. chardev that should be unusable).
> >
> > If it is usable with no control in place for buffers or other stuff
> > (i.e. I missed something), then I also don't know.
> >
> > So, this patch on it's own can still be interpreted as an RFC.
> > See:
> > https://lore.kernel.org/linux-iio/20201121180246.772ad299@archlinux/
>
> Don't take me wrong, I'm not against a good change (I doesn't like
> dangling files), but it might break some use cases.

Yeah I know.
But how else do you know if a dangling file might break some use cases?

The worst that would happen is that we get a report and create a Fixes
tag and we know.
But if we don't try it, we're stuck with it, and will never know.

>
> --
> With Best Regards,
> Andy Shevchenko