On Tue, 3 Feb 2026 07:10:54 +0100, Tzung-Bi Shih <[email protected]> said:
> The underlying chip can be removed asynchronously. `gdev->srcu` is used
> to ensure the synchronization before accessing `gdev->chip`.
>
> Revocable encapsulates the details. Add revocable provider handle for
> the corresponding struct gpio_chip in struct gpio_device so that it can
> start to hide the synchronization details.
>
> Signed-off-by: Tzung-Bi Shih <[email protected]>
> ---
[snip]
> diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
> index 3abb90385829..cd136d5b52e9 100644
> --- a/drivers/gpio/gpiolib.h
> +++ b/drivers/gpio/gpiolib.h
> @@ -52,6 +52,7 @@
> * @device_notifier: used to notify character device wait queues about the
> GPIO
> * device being unregistered
> * @srcu: protects the pointer to the underlying GPIO chip
> + * @chip_rp: revocable provider handle for the corresponding struct
> gpio_chip.
> * @pin_ranges: range of pins served by the GPIO driver
> *
> * This state container holds most of the runtime variable data
> @@ -79,6 +80,7 @@ struct gpio_device {
> struct workqueue_struct *line_state_wq;
> struct blocking_notifier_head device_notifier;
> struct srcu_struct srcu;
> + struct revocable_provider __rcu *chip_rp;
>
Why __rcu? This doesn't live in a different address space, only the internal
resource it protects does. If anything - this could be __attribute__((noderef))
but even that is questionable as this is an opaque structure.
Bart
> #ifdef CONFIG_PINCTRL
> /*
> --
> 2.53.0.rc2.204.g2597b5adb4-goog
>
>
