gpio: wm831x: use gpiochip_dup_line_label()

Use the new gpiochip_dup_line_label() helper to safely retrieve the
descriptor label.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-wm831x.c

@@ -8,6 +8,7 @@
  *
  */
 
+#include <linux/cleanup.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/module.h>
@@ -160,18 +161,21 @@ static void wm831x_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 	for (i = 0; i < chip->ngpio; i++) {
 		int gpio = i + chip->base;
 		int reg;
-		const char *label, *pull, *powerdomain;
+		const char *pull, *powerdomain;
 
 		/* We report the GPIO even if it's not requested since
 		 * we're also reporting things like alternate
 		 * functions which apply even when the GPIO is not in
 		 * use as a GPIO.
 		 */
-		label = gpiochip_is_requested(chip, i);
-		if (!label)
-			label = "Unrequested";
+		char *label __free(kfree) = gpiochip_dup_line_label(chip, i);
+		if (IS_ERR(label)) {
+			dev_err(wm831x->dev, "Failed to duplicate label\n");
+			continue;
+		}
 
-		seq_printf(s, " gpio-%-3d (%-20.20s) ", gpio, label);
+		seq_printf(s, " gpio-%-3d (%-20.20s) ",
+			   gpio, label ?: "Unrequested");
 
 		reg = wm831x_reg_read(wm831x, WM831X_GPIO1_CONTROL + i);
 		if (reg < 0) {