[PATCH] staging: greybus: light: initialize channel lock before registration

gb_lights_light_register() registers each channel before initializing
light->channels[i].lock. Channel registration exposes the LED class
device and its brightness callback, which later takes this mutex. A
concurrent brightness update can therefore hit an uninitialized lock.

Initialize the channel mutex before registering the channel so the
callback always sees a valid lock.

Fixes: cc43368a3cde ("greybus: lights: Control runtime pm suspend/resume on AP side")
Cc: [email protected]
Signed-off-by: Runyu Xiao <[email protected]>
---
 drivers/staging/greybus/light.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
index 38c233a706c4..056ef6b0276e 100644
--- a/drivers/staging/greybus/light.c
+++ b/drivers/staging/greybus/light.c
@@ -1043,11 +1043,11 @@ static int gb_lights_light_register(struct gb_light *light)
 	 * found.
 	 */
 	for (i = 0; i < light->channels_count; i++) {
+		mutex_init(&light->channels[i].lock);
+
 		ret = gb_lights_channel_register(&light->channels[i]);
 		if (ret < 0)
 			return ret;
-
-		mutex_init(&light->channels[i].lock);
 	}
 
 	light->ready = true;
-- 
2.34.1