Commit d2e2586a authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

gpio: cdev: wake up chardev poll() on device unbind 



Add a notifier block to the gpio_chardev_data structure and register it
with the gpio_device's device notifier. Upon reception of an event, wake
up the wait queue so that the user-space be forced out of poll() and need
to go into a new system call which will then fail due to the chip being
gone.

Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Reviewed-by: default avatarKent Gibson <warthog618@gmail.com>
parent a067419b

drivers/gpio/gpiolib-cdev.c

+27 −2
Original line number Diff line number Diff line
@@ -2320,6 +2320,7 @@ struct gpio_chardev_data { 
	wait_queue_head_t wait;

	DECLARE_KFIFO(events, struct gpio_v2_line_info_changed, 32);

	struct notifier_block lineinfo_changed_nb;

	struct notifier_block device_unregistered_nb;

	unsigned long *watched_lines;

#ifdef CONFIG_GPIO_CDEV_V1

	atomic_t watch_abi_version;
@@ -2517,6 +2518,18 @@ static int lineinfo_changed_notify(struct notifier_block *nb, 
	return NOTIFY_OK;

}



static int gpio_device_unregistered_notify(struct notifier_block *nb,

					   unsigned long action, void *data)

{

	struct gpio_chardev_data *cdev = container_of(nb,

						      struct gpio_chardev_data,

						      device_unregistered_nb);



	wake_up_poll(&cdev->wait, EPOLLIN | EPOLLERR);



	return NOTIFY_OK;

}



static __poll_t lineinfo_watch_poll_unlocked(struct file *file,

					     struct poll_table_struct *pollt)

{
@@ -2671,17 +2684,27 @@ static int gpio_chrdev_open(struct inode *inode, struct file *file) 
	if (ret)

		goto out_free_bitmap;



	cdev->device_unregistered_nb.notifier_call =

					gpio_device_unregistered_notify;

	ret = blocking_notifier_chain_register(&gdev->device_notifier,

					       &cdev->device_unregistered_nb);

	if (ret)

		goto out_unregister_line_notifier;



	file->private_data = cdev;



	ret = nonseekable_open(inode, file);

	if (ret)

		goto out_unregister_notifier;

		goto out_unregister_device_notifier;



	up_read(&gdev->sem);



	return ret;



out_unregister_notifier:

out_unregister_device_notifier:

	blocking_notifier_chain_unregister(&gdev->device_notifier,

					   &cdev->device_unregistered_nb);

out_unregister_line_notifier:

	blocking_notifier_chain_unregister(&gdev->line_state_notifier,

					   &cdev->lineinfo_changed_nb);

out_free_bitmap:
@@ -2706,6 +2729,8 @@ static int gpio_chrdev_release(struct inode *inode, struct file *file) 
	struct gpio_device *gdev = cdev->gdev;



	bitmap_free(cdev->watched_lines);

	blocking_notifier_chain_unregister(&gdev->device_notifier,

					   &cdev->device_unregistered_nb);

	blocking_notifier_chain_unregister(&gdev->line_state_notifier,

					   &cdev->lineinfo_changed_nb);

	gpio_device_put(gdev);