Commit a0dda508 authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

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



Add a notifier block to the linereq 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 d2e2586a

drivers/gpio/gpiolib-cdev.c

+23 −0
Original line number Diff line number Diff line
@@ -555,6 +555,7 @@ struct line { 
 * @label: consumer label used to tag GPIO descriptors

 * @num_lines: the number of lines in the lines array

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

 * @device_unregistered_nb: notifier block for receiving gdev unregister events

 * @event_buffer_size: the number of elements allocated in @events

 * @events: KFIFO for the GPIO events

 * @seqno: the sequence number for edge events generated on all lines in
@@ -569,6 +570,7 @@ struct linereq { 
	const char *label;

	u32 num_lines;

	wait_queue_head_t wait;

	struct notifier_block device_unregistered_nb;

	u32 event_buffer_size;

	DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);

	atomic_t seqno;
@@ -610,6 +612,17 @@ struct linereq { 
	 GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE | \

	 GPIO_V2_LINE_EDGE_FLAGS)



static int linereq_unregistered_notify(struct notifier_block *nb,

				       unsigned long action, void *data)

{

	struct linereq *lr = container_of(nb, struct linereq,

					  device_unregistered_nb);



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



	return NOTIFY_OK;

}



static void linereq_put_event(struct linereq *lr,

			      struct gpio_v2_line_event *le)

{
@@ -1567,6 +1580,10 @@ static void linereq_free(struct linereq *lr) 
{

	unsigned int i;



	if (lr->device_unregistered_nb.notifier_call)

		blocking_notifier_chain_unregister(&lr->gdev->device_notifier,

						   &lr->device_unregistered_nb);



	for (i = 0; i < lr->num_lines; i++) {

		if (lr->lines[i].desc) {

			edge_detector_stop(&lr->lines[i]);
@@ -1727,6 +1744,12 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) 
			offset);

	}



	lr->device_unregistered_nb.notifier_call = linereq_unregistered_notify;

	ret = blocking_notifier_chain_register(&gdev->device_notifier,

					       &lr->device_unregistered_nb);

	if (ret)

		goto out_free_linereq;



	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);

	if (fd < 0) {

		ret = fd;