[PATCH 18/21] leds: aw2013: Unlock chip mutex before registering LEDs

[Lee Jones]

aw2013_probe() holds chip->mutex across aw2013_probe_dt(), which calls
devm_led_classdev_register_ext().  When a default trigger such as
"timer" is configured on an LED in the Device Tree, the LED core
synchronously activates the trigger during registration and invokes
aw2013_blink_set() on the same thread, which attempts to acquire
chip->mutex and deadlocks.

Reset the chip, disable the regulators, and release chip->mutex in
aw2013_probe() before calling aw2013_probe_dt(), and update
chip->num_leds before each LED is registered so trigger callbacks can
enable the chip cleanly during registration.

Fixes: 59ea3c9faf32 ("leds: add aw2013 driver")
Closes: https://sashiko.dev/#/bug/linux-5e2c9083-b95b-4aa4-aa0a-b0be8865ff12
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
---
 drivers/leds/leds-aw2013.c | 54 ++++++++++++++++++++++----------------
 1 file changed, 32 insertions(+), 22 deletions(-)

diff --git a/drivers/leds/leds-aw2013.c b/drivers/leds/leds-aw2013.c
index dfeac8b2993f..c947cd068963 100644
--- a/drivers/leds/leds-aw2013.c
+++ b/drivers/leds/leds-aw2013.c
@@ -271,8 +271,6 @@ static int aw2013_probe_dt(struct aw2013 *chip)
 	if (!count || count > AW2013_MAX_LEDS)
 		return -EINVAL;
 
-	regmap_write(chip->regmap, AW2013_RSTR, AW2013_RSTR_RESET);
-
 	for_each_available_child_of_node_scoped(np, child) {
 		struct led_init_data init_data = {};
 		u32 source;
@@ -305,19 +303,29 @@ static int aw2013_probe_dt(struct aw2013 *chip)
 		led->cdev.brightness_set_blocking = aw2013_brightness_set;
 		led->cdev.blink_set = aw2013_blink_set;
 
+		mutex_lock(&chip->mutex);
+		chip->num_leds = ++i;
+		if (chip->enabled) {
+			ret = regmap_update_bits(chip->regmap,
+						 AW2013_LCFG(led->num),
+						 AW2013_LCFG_IMAX_MASK,
+						 led->imax);
+			if (ret) {
+				mutex_unlock(&chip->mutex);
+				return ret;
+			}
+		}
+		mutex_unlock(&chip->mutex);
+
 		ret = devm_led_classdev_register_ext(&chip->client->dev,
 						     &led->cdev, &init_data);
 		if (ret < 0)
 			return ret;
-
-		i++;
 	}
 
 	if (!count)
 		return -EINVAL;
 
-	chip->num_leds = i;
-
 	return 0;
 }
 
@@ -393,25 +401,27 @@ static int aw2013_probe(struct i2c_client *client)
 		goto error_reg;
 	}
 
+	ret = regmap_write(chip->regmap, AW2013_RSTR, AW2013_RSTR_RESET);
+	if (ret) {
+		dev_err(&client->dev, "Failed to reset chip: %d\n", ret);
+		goto error_reg;
+	}
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(chip->regulators),
+				     chip->regulators);
+	if (ret) {
+		dev_err(&client->dev,
+			"Failed to disable regulators: %d\n", ret);
+		goto error;
+	}
+
+	mutex_unlock(&chip->mutex);
+
 	ret = devm_add_action(&client->dev, aw2013_chip_disable_action, chip);
 	if (ret)
-		goto error_reg;
+		return ret;
 
-	ret = aw2013_probe_dt(chip);
-	if (ret < 0)
-		goto error_reg;
-
-	ret = regulator_bulk_disable(ARRAY_SIZE(chip->regulators),
-				     chip->regulators);
-	if (ret) {
-		dev_err(&client->dev,
-			"Failed to disable regulators: %d\n", ret);
-		goto error;
-	}
-
-	mutex_unlock(&chip->mutex);
-
-	return 0;
+	return aw2013_probe_dt(chip);
 
 error_reg:
 	regulator_bulk_disable(ARRAY_SIZE(chip->regulators),
-- 
2.56.0.218.g1ec904b173-goog