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Message-Id: <20230817184958.25349-6-brgl@bgdev.pl>
Date: Thu, 17 Aug 2023 20:49:57 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Kent Gibson <warthog618@...il.com>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v2 5/6] gpio: cdev: wake up linereq poll() on device unbind
From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
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@...aro.org>
---
drivers/gpio/gpiolib-cdev.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 8b081c9b8d27..4c3b186bc638 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;
--
2.39.2
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