[PATCH v2 2/4] gpio: shared: gracefully handle no-device lookup of shared GPIOs

[Bartosz Golaszewski]

We use platform lookup tables for shared GPIOs. This mechanism needs a
struct device to work so fwnode-based lookup with no device associated
currently causes a NULL-pointer deference.

Adding this functionality will require a larger rework and it has never
worked anyway so add a check that allows the kernel to gracefully handle
this situation with an error ahead of implementing that functionality as
a new feature.

Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Abel Vesa <abelvesa@xxxxxxxxxx>
Fixes: a060b8c511ab ("gpiolib: implement low-level, shared GPIO support")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
---
 drivers/gpio/gpiolib-shared.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-shared.c b/drivers/gpio/gpiolib-shared.c
index 6acfec73b73477245c7e4c593f2925efbc8980c6..8c9ac9d9330490b17fb3936b8758beb97a308a15 100644
--- a/drivers/gpio/gpiolib-shared.c
+++ b/drivers/gpio/gpiolib-shared.c
@@ -449,9 +449,14 @@ static bool gpio_shared_dev_is_reset_gpio(struct device *consumer,
 int gpio_shared_add_proxy_lookup(struct device *consumer, struct fwnode_handle *fwnode,
 				 const char *con_id, unsigned long lflags)
 {
-	const char *dev_id = dev_name(consumer);
 	struct gpio_shared_entry *entry;
 	struct gpio_shared_ref *ref;
+	const char *dev_id;
+
+	if (!consumer)
+		return -EOPNOTSUPP;
+
+	dev_id = dev_name(consumer);
 
 	list_for_each_entry(entry, &gpio_shared_list, list) {
 		list_for_each_entry(ref, &entry->refs, list) {

-- 
2.47.3