Input: turbografx - use guard notation when acquiring mutex

Using guard notation makes the code more compact and error handling
more robust by ensuring that mutexes are released in all code paths
when control leaves critical section.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/joystick/turbografx.c

···
 static int tgfx_open(struct input_dev *dev)
 {
 	struct tgfx *tgfx = input_get_drvdata(dev);
-	int err;
 
-	err = mutex_lock_interruptible(&tgfx->sem);
-	if (err)
-		return err;
+	scoped_guard(mutex_intr, &tgfx->sem) {
+		if (!tgfx->used++) {
+			parport_claim(tgfx->pd);
+			parport_write_control(tgfx->pd->port, 0x04);
+			mod_timer(&tgfx->timer, jiffies + TGFX_REFRESH_TIME);
+		}
 
-	if (!tgfx->used++) {
-		parport_claim(tgfx->pd);
-		parport_write_control(tgfx->pd->port, 0x04);
-		mod_timer(&tgfx->timer, jiffies + TGFX_REFRESH_TIME);
+		return 0;
 	}
 
-	mutex_unlock(&tgfx->sem);
-	return 0;
+	return -EINTR;
 }
 
 static void tgfx_close(struct input_dev *dev)
 {
 	struct tgfx *tgfx = input_get_drvdata(dev);
 
-	mutex_lock(&tgfx->sem);
+	guard(mutex)(&tgfx->sem);
+
 	if (!--tgfx->used) {
 		del_timer_sync(&tgfx->timer);
 		parport_write_control(tgfx->pd->port, 0x00);
 		parport_release(tgfx->pd);
 	}
-	mutex_unlock(&tgfx->sem);
 }