Commit 7b9b77a8 authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

gpiolib: add a per-gpio_device line state notification workqueue 



In order to prepare the line state notification mechanism for working in
atomic context as well, add a dedicated, high-priority, ordered
workqueue to GPIO device which will be used to queue the events fron any
context for them to be emitted always in process context.

Reviewed-by: default avatarKent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-5-c79135e58a1c@linaro.org


Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
parent 8c44447b

drivers/gpio/gpiolib-cdev.c

+6 −0
Original line number Diff line number Diff line
@@ -2749,6 +2749,11 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt) 
	gdev->chrdev.owner = THIS_MODULE;

	gdev->dev.devt = MKDEV(MAJOR(devt), gdev->id);



	gdev->line_state_wq = alloc_ordered_workqueue(dev_name(&gdev->dev),

						      WQ_HIGHPRI);

	if (!gdev->line_state_wq)

		return -ENOMEM;



	ret = cdev_device_add(&gdev->chrdev, &gdev->dev);

	if (ret)

		return ret;
@@ -2765,6 +2770,7 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt) 


void gpiolib_cdev_unregister(struct gpio_device *gdev)

{

	destroy_workqueue(gdev->line_state_wq);

	cdev_device_del(&gdev->chrdev, &gdev->dev);

	blocking_notifier_call_chain(&gdev->device_notifier, 0, NULL);

}

drivers/gpio/gpiolib.h

+4 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/module.h>

#include <linux/notifier.h>

#include <linux/srcu.h>

#include <linux/workqueue.h>



#define GPIOCHIP_NAME	"gpiochip"
@@ -44,6 +45,8 @@ 
 * @list: links gpio_device:s together for traversal

 * @line_state_notifier: used to notify subscribers about lines being

 *                       requested, released or reconfigured

 * @line_state_wq: used to emit line state events from a separate thread in

 *                 process context

 * @device_notifier: used to notify character device wait queues about the GPIO

 *                   device being unregistered

 * @srcu: protects the pointer to the underlying GPIO chip
@@ -70,6 +73,7 @@ struct gpio_device { 
	void			*data;

	struct list_head        list;

	struct blocking_notifier_head line_state_notifier;

	struct workqueue_struct	*line_state_wq;

	struct blocking_notifier_head device_notifier;

	struct srcu_struct	srcu;