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gpiolib: add a per-gpio_device line state notification workqueue

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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: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-5-c79135e58a1c@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Bartosz Golaszewski 2024-10-18 11:10:13 +02:00
parent 8c44447bd7
commit 7b9b77a8bb
2 changed files with 10 additions and 0 deletions
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6
drivers/gpio/gpiolib-cdev.c
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@ -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);
}

4
drivers/gpio/gpiolib.h
View file

@ -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;