linux-kernel - Re: [PATCH v2 0/2] gpio: create the /sys/class/gpio mount point with GPIO

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Message-ID: <CAMRc=Md6cnxz=L99aaM7a-zeHNnJGXm0P-rNJJ5r0WwRAwb2tg@mail.gmail.com>
Date: Tue, 12 Nov 2024 11:04:24 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Linus Walleij <linus.walleij@...aro.org>, 
	Kent Gibson <warthog618@...il.com>, linux-kernel@...r.kernel.org, 
	linux-gpio@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 0/2] gpio: create the /sys/class/gpio mount point with
 GPIO_SYSFS disabled

On Tue, Oct 15, 2024 at 2:46 PM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> >
> > What if we just add a Kconfig option allowing to disable the sysfs
> > attributes inside /sys/class/gpio but keep the directory? It's not
> > like it's a new one, it's already there as a baked in interface.
>
> That's up to you, but again, please do not mount a filesystem there,
> that's going to cause nothing but problems in the end (like debugfs and
> tracefs and configfs do all the time when people get confused and start
> poking around in sysfs code looking for the logic involved in other
> places.)
>

Fortunately no kernel change is required after all. The user-space can
work around it ekhm... "elegantly" by mounting a read-only overlay on
top of /sys/class that contains the gpio directory and mounting the
user-space compatibility layer onto it. I know you don't like it
either but at least I won't be submitting any such proposal to the
kernel anymore. :)

Bartosz