Re: [PATCH v9] gpio: virtuser: new virtual testing driver for the GPIO API

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Thu, Jun 27, 2024 at 1:51 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
>
> From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>
> The GPIO subsystem used to have a serious problem with undefined behavior
> and use-after-free bugs on hot-unplug of GPIO chips. This can be
> considered a corner-case by some as most GPIO controllers are enabled
> early in the boot process and live until the system goes down but most
> GPIO drivers do allow unbind over sysfs, many are loadable modules that
> can be (force) unloaded and there are also GPIO devices that can be
> dynamically detached, for instance CP2112 which is a USB GPIO expender.
>
> Bugs can be triggered both from user-space as well as by in-kernel users.
> We have the means of testing it from user-space via the character device
> but the issues manifest themselves differently in the kernel.
>
> This is a proposition of adding a new virtual driver - a configurable
> GPIO consumer that can be configured over configfs (similarly to
> gpio-sim) or described on the device-tree.
>
> This driver is aimed as a helper in spotting any regressions in
> hot-unplug handling in GPIOLIB.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
> ---

With no objections, I'll queue it early next week.

Bart