Commit 9d7697fa authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

gpio: shared: fix lockdep false positive by removing unneeded lock 



By the time gpio_device_teardown_shared() is called, the parent device
is gone from the global list of GPIO devices and all outstanding SRCU
read-side critical sections have completed. That means that no
concurrent gpio_find_and_request() can call
gpio_shared_add_proxy_lookup() for this device at this time. There's
also no risk of the parent device being re-bound to the driver before
the unbinding completes (including the child devices).

Lockdep produces a false-positive report about a possible circular
dependency as it doesn't know the ordering guarantee. Not taking the
ref->lock in gpio_device_teardown_shared() silences it and is safe to do.

Cc: stable@vger.kernel.org
Fixes: ea513dd3 ("gpio: shared: make locking more fine-grained")
Reviewed-by: default avatarLinus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260522-gpio-shared-deadlock-v1-2-76bca088f8c0@oss.qualcomm.com


Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
parent a1b83660

drivers/gpio/gpiolib-shared.c

+0 −2
Original line number Diff line number Diff line
@@ -605,8 +605,6 @@ void gpio_device_teardown_shared(struct gpio_device *gdev) 
			gpiod_free_commit(&gdev->descs[entry->offset]);



		list_for_each_entry(ref, &entry->refs, list) {

			guard(mutex)(&ref->lock);



			if (ref->lookup) {

				gpiod_remove_lookup_table(ref->lookup);

				kfree(ref->lookup->table[0].key);