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From:   Bartosz Golaszewski <bgolaszewski@baylibre.com>
Date:   Thu, 20 May 2021 15:02:14 +0200
Message-ID: <CAMpxmJVJBx2J87bS0CUYPyJkHKt=nvFw65y_+iG-5JbVekuaqw@mail.gmail.com>
Subject: Re: [PATCH v1 1/2] gpiolib: Never return internal error codes to user space
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Kent Gibson <warthog618@gmail.com>,
        linux-gpio <linux-gpio@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Suresh Balakrishnan <suresh.balakrishnan@intel.com>
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On Wed, May 19, 2021 at 10:30 AM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Wed, May 19, 2021 at 04:04:34PM +0800, Kent Gibson wrote:
> > On Wed, May 19, 2021 at 10:45:16AM +0300, Andy Shevchenko wrote:
> > > On Wed, May 19, 2021 at 07:24:51AM +0800, Kent Gibson wrote:
> > > > On Tue, May 18, 2021 at 06:50:12PM +0300, Andy Shevchenko wrote:
> > > > > Currently it's possible that character device interface may return
> > > > > the error codes which are not supposed to be seen by user space.
> > > > > In this case it's EPROBE_DEFER.
> > > > >
> > > > > Wrap it to return -ENODEV instead as sysfs does.
> > >
> > > > > Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines")
> > > > > Fixes: 61f922db7221 ("gpio: userspace ABI for reading GPIO line events")
> > > > > Fixes: 3c0d9c635ae2 ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
> > >
> > > ...
> > >
> > > > You immediately revert this patch in patch 2.
> > > > My understanding is that is not allowed within a patch set.
> > >
> > > > Why split the patches instead of going direct to the new helper?
> > >
> > > It's for backporting to make it easier. (I deliberately left the context above)
> > >
> > > I can fold them if maintainers think it's okay to do.
> > >
> >
> > Not sure what the constraints are on backporting, but wouldn't it be
> > simpler and cleaner to backport the new helper?
>
> Logically (and ideally) it would be three different patches:
>  1) introduce helper
>  2) use helper
>  3) fix places where it's needed to be done
>
> But the above scheme doesn't fit backporting idea (we don't backport new
> features and APIs without really necessity). So, the options left are:
>
> Option a: One patch (feels a bit like above)
> Option b: Two patches like in this series (yes, you are correct about
>           disadvantages)
>
> > But, as you say, it is the maintainers' call.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Third option is to backport this patch but apply the helper
immediately to master.

Bart