[PATCH] hid: cp2112: Fix duplicate workqueue initialization

[Danny Kaehn <danny.kaehn@plexus.com>]

Previously the cp2112 driver called INIT_DELAYED_WORK within
cp2112_gpio_irq_startup, resulting in duplicate initilizations of the
workqueue on subsequent IRQ startups following an initial request. This
resulted in a warning in set_work_data in workqueue.c, as well as a rare
NULL dereference within process_one_work in workqueue.c.

Initialize the workqueue within _probe instead.

Signed-off-by: Danny Kaehn <danny.kaehn@plexus.com>
---

Note -- the warning & NULL dereference that were caused by this were
completely decoupled from the driver code, making this a fairly tricky
bug to track down. I wonder if there would be a way to add a WARN into
__INIT_WORK if an already initialized workqueue is re-initialized
without a lot of overhead...

 drivers/hid/hid-cp2112.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-cp2112.c b/drivers/hid/hid-cp2112.c
index 54c33a24f844..36f76c6dfa20 100644
--- a/drivers/hid/hid-cp2112.c
+++ b/drivers/hid/hid-cp2112.c
@@ -1151,8 +1151,6 @@ static unsigned int cp2112_gpio_irq_startup(struct irq_data *d)
 	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
 	struct cp2112_device *dev = gpiochip_get_data(gc);
 
-	INIT_DELAYED_WORK(&dev->gpio_poll_worker, cp2112_gpio_poll_callback);
-
 	if (!dev->gpio_poll) {
 		dev->gpio_poll = true;
 		schedule_delayed_work(&dev->gpio_poll_worker, 0);
@@ -1307,6 +1305,8 @@ static int cp2112_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	girq->handler = handle_simple_irq;
 	girq->threaded = true;
 
+	INIT_DELAYED_WORK(&dev->gpio_poll_worker, cp2112_gpio_poll_callback);
+
 	ret = gpiochip_add_data(&dev->gc, dev);
 	if (ret < 0) {
 		hid_err(hdev, "error registering gpio chip\n");
-- 
2.25.1