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authorBartosz Golaszewski <bartosz.golaszewski@linaro.org>2023-08-17 15:18:58 +0200
committerBartosz Golaszewski <bartosz.golaszewski@linaro.org>2023-08-21 15:57:05 +0200
commita0dda508bd66b9eeeedc6fe0597aa8613f4b3c5d (patch)
tree97e1cdb3c5cb467a4ffbd58a395d7044cd57aa25 /drivers/gpio
parentgpio: cdev: wake up chardev poll() on device unbind (diff)
downloadlinux-a0dda508bd66b9eeeedc6fe0597aa8613f4b3c5d.tar.xz
linux-a0dda508bd66b9eeeedc6fe0597aa8613f4b3c5d.zip
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: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Kent Gibson <warthog618@gmail.com>
Diffstat (limited to 'drivers/gpio')
-rw-r--r--drivers/gpio/gpiolib-cdev.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index bc1542544e49..7d0c83127ccb 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -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;