Re: [PATCH v2 0/6] gpio: cdev: bail out of poll() if the device goes down

[Bartosz Golaszewski]

On Fri, Aug 18, 2023 at 12:34 PM Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>
> On Thu, Aug 17, 2023 at 08:49:52PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
> >
> > Wake up all three wake queues (the one associated with the character
> > device file, the one for V1 line events and the V2 line request one)
> > when the underlying GPIO device is unregistered. This way we won't get
> > stuck in poll() after the chip is gone as user-space will be forced to
> > go back into a new system call and will see that gdev->chip is NULL.
>
> Why can't you use the global device unbind notifications and filter out
> what you are interested in?
>

There's no truly global device unbind notification - only per-bus.
GPIO devices can reside on any bus, there are no limitations and so
we'd have to subscribe to all of them.

Bart