From 7b9b77a8bba9c1fd7bad3310dbf2cf382e1f8c25 Mon Sep 17 00:00:00 2001 From: Bartosz Golaszewski Date: Fri, 18 Oct 2024 11:10:13 +0200 Subject: [PATCH] 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: Kent Gibson Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-5-c79135e58a1c@linaro.org Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib-cdev.c | 6 ++++++ drivers/gpio/gpiolib.h | 4 ++++ 2 files changed, 10 insertions(+) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index 0cba74381687a..b242fdb1ad288 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -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); } diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 8daba06eb472f..8737e16412783 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -17,6 +17,7 @@ #include #include #include +#include #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;