leds: lm3642: Use guard to simplify locking

The mutex_lock()/mutex_unlock() pattern requires explicitly pairing
lock and unlock calls. Use guard(mutex) instead so the lock is
automatically released when the scope exits.

Convert to guard(mutex) in lm3642_torch_brightness_set(),
lm3642_strobe_brightness_set(), and lm3642_indicator_brightness_set().
Add #include <linux/cleanup.h> to support scoped guards.

Signed-off-by: Richard Lyu <richard.lyu@suse.com>
Link: https://patch.msgid.link/20260320035451.31071-1-richard.lyu@suse.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: r1chard-lyu

drivers/leds/leds-lm3642.c

@@ -3,15 +3,16 @@
 * Simple driver for Texas Instruments LM3642 LED Flash driver chip
 * Copyright (C) 2012 Texas Instruments
 */
-#include <linux/module.h>
+#include <linux/cleanup.h>
 #include <linux/delay.h>
+#include <linux/fs.h>
 #include <linux/i2c.h>
 #include <linux/leds.h>
-#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/platform_data/leds-lm3642.h>
 #include <linux/platform_device.h>
-#include <linux/fs.h>
 #include <linux/regmap.h>
-#include <linux/platform_data/leds-lm3642.h>
+#include <linux/slab.h>
 
 #define	REG_FILT_TIME			(0x0)
 #define	REG_IVFM_MODE			(0x1)
@@ -202,10 +203,9 @@ static int lm3642_torch_brightness_set(struct led_classdev *cdev,
 	    container_of(cdev, struct lm3642_chip_data, cdev_torch);
 	int ret;
 
-	mutex_lock(&chip->lock);
+	guard(mutex)(&chip->lock);
 	chip->br_torch = brightness;
 	ret = lm3642_control(chip, chip->br_torch, MODES_TORCH);
-	mutex_unlock(&chip->lock);
 	return ret;
 }
 
@@ -249,10 +249,9 @@ static int lm3642_strobe_brightness_set(struct led_classdev *cdev,
 	    container_of(cdev, struct lm3642_chip_data, cdev_flash);
 	int ret;
 
-	mutex_lock(&chip->lock);
+	guard(mutex)(&chip->lock);
 	chip->br_flash = brightness;
 	ret = lm3642_control(chip, chip->br_flash, MODES_FLASH);
-	mutex_unlock(&chip->lock);
 	return ret;
 }
 
@@ -264,10 +263,9 @@ static int lm3642_indicator_brightness_set(struct led_classdev *cdev,
 	    container_of(cdev, struct lm3642_chip_data, cdev_indicator);
 	int ret;
 
-	mutex_lock(&chip->lock);
+	guard(mutex)(&chip->lock);
 	chip->br_indicator = brightness;
 	ret = lm3642_control(chip, chip->br_indicator, MODES_INDIC);
-	mutex_unlock(&chip->lock);
 	return ret;
 }