[PATCH 4/6] Input: n64joy - use guard notation when acquiring mutex

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

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.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/joystick/n64joy.c | 35 +++++++++++++++------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/drivers/input/joystick/n64joy.c b/drivers/input/joystick/n64joy.c
index b0986d2195d6..c344dbc0c493 100644
--- a/drivers/input/joystick/n64joy.c
+++ b/drivers/input/joystick/n64joy.c
@@ -191,35 +191,32 @@ static void n64joy_poll(struct timer_list *t)
 static int n64joy_open(struct input_dev *dev)
 {
 	struct n64joy_priv *priv = input_get_drvdata(dev);
-	int err;
-
-	err = mutex_lock_interruptible(&priv->n64joy_mutex);
-	if (err)
-		return err;
-
-	if (!priv->n64joy_opened) {
-		/*
-		 * We could use the vblank irq, but it's not important if
-		 * the poll point slightly changes.
-		 */
-		timer_setup(&priv->timer, n64joy_poll, 0);
-		mod_timer(&priv->timer, jiffies + msecs_to_jiffies(16));
-	}
 
-	priv->n64joy_opened++;
+	scoped_guard(mutex_intr, &priv->n64joy_mutex) {
+		if (!priv->n64joy_opened) {
+			/*
+			 * We could use the vblank irq, but it's not important
+			 * if the poll point slightly changes.
+			 */
+			timer_setup(&priv->timer, n64joy_poll, 0);
+			mod_timer(&priv->timer, jiffies + msecs_to_jiffies(16));
+		}
 
-	mutex_unlock(&priv->n64joy_mutex);
-	return err;
+		priv->n64joy_opened++;
+		return 0;
+	}
+
+	return -EINTR;
 }
 
 static void n64joy_close(struct input_dev *dev)
 {
 	struct n64joy_priv *priv = input_get_drvdata(dev);
 
-	mutex_lock(&priv->n64joy_mutex);
+	guard(mutex)(&priv->n64joy_mutex);
+
 	if (!--priv->n64joy_opened)
 		del_timer_sync(&priv->timer);
-	mutex_unlock(&priv->n64joy_mutex);
 }
 
 static const u64 __initconst scandata[] ____cacheline_aligned = {
-- 
2.46.0.469.g59c65b2a67-goog