Re: [PATCH RFT v2] gpio: cdev: use raw notifier for line state events

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>


On Tue, 11 Mar 2025 15:31:43 +0100, Bartosz Golaszewski wrote:
> We use a notifier to implement the mechanism of informing the user-space
> about changes in GPIO line status. We register with the notifier when
> the GPIO character device file is opened and unregister when the last
> reference to the associated file descriptor is dropped.
> 
> Since commit fcc8b637c542 ("gpiolib: switch the line state notifier to
> atomic") we use the atomic notifier variant. Atomic notifiers call
> rcu_synchronize in atomic_notifier_chain_unregister() which caused a
> significant performance regression in some circumstances, observed by
> user-space when calling close() on the GPIO device file descriptor.
> 
> [...]

Applied, thanks!

[1/1] gpio: cdev: use raw notifier for line state events
      commit: dcb73cbaaeb39c9fd00bf2e019f911725945e2fe

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>