Commit 91043f55 authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

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



Add a notifier block to the lineevent_state 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 a0dda508

drivers/gpio/gpiolib-cdev.c

+22 −0
Original line number Diff line number Diff line
@@ -1802,6 +1802,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) 
 * @eflags: the event flags this line was requested with

 * @irq: the interrupt that trigger in response to events on this GPIO

 * @wait: wait queue that handles blocking reads of events

 * @device_unregistered_nb: notifier block for receiving gdev unregister events

 * @events: KFIFO for the GPIO events

 * @timestamp: cache for the timestamp storing it between hardirq

 * and IRQ thread, used to bring the timestamp close to the actual
@@ -1814,6 +1815,7 @@ struct lineevent_state { 
	u32 eflags;

	int irq;

	wait_queue_head_t wait;

	struct notifier_block device_unregistered_nb;

	DECLARE_KFIFO(events, struct gpioevent_data, 16);

	u64 timestamp;

};
@@ -1847,6 +1849,17 @@ static __poll_t lineevent_poll(struct file *file, 
	return call_poll_locked(file, wait, le->gdev, lineevent_poll_unlocked);

}



static int lineevent_unregistered_notify(struct notifier_block *nb,

					 unsigned long action, void *data)

{

	struct lineevent_state *le = container_of(nb, struct lineevent_state,

						  device_unregistered_nb);



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



	return NOTIFY_OK;

}



struct compat_gpioeevent_data {

	compat_u64	timestamp;

	u32		id;
@@ -1932,6 +1945,9 @@ static ssize_t lineevent_read(struct file *file, char __user *buf, 


static void lineevent_free(struct lineevent_state *le)

{

	if (le->device_unregistered_nb.notifier_call)

		blocking_notifier_chain_unregister(&le->gdev->device_notifier,

						   &le->device_unregistered_nb);

	if (le->irq)

		free_irq(le->irq, le);

	if (le->desc)
@@ -2160,6 +2176,12 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip) 
	INIT_KFIFO(le->events);

	init_waitqueue_head(&le->wait);



	le->device_unregistered_nb.notifier_call = lineevent_unregistered_notify;

	ret = blocking_notifier_chain_register(&gdev->device_notifier,

					       &le->device_unregistered_nb);

	if (ret)

		goto out_free_le;



	/* Request a thread to read the events */

	ret = request_threaded_irq(irq,

				   lineevent_irq_handler,