[PATCH v2 17/22] Input: pegasus_notetaker - 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.

Reviewed-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---

V2: fixed whitespace issues, added Reviewed-by from Javier

 drivers/input/tablet/pegasus_notetaker.c |   86 +++++++++++++++++-------------
 1 file changed, 48 insertions(+), 38 deletions(-)

diff --git a/drivers/input/tablet/pegasus_notetaker.c b/drivers/input/tablet/pegasus_notetaker.c
index a68da2988f9c..8d6b71d59793 100644
--- a/drivers/input/tablet/pegasus_notetaker.c
+++ b/drivers/input/tablet/pegasus_notetaker.c
@@ -214,6 +214,28 @@ static void pegasus_init(struct work_struct *work)
 			error);
 }
 
+static int __pegasus_open(struct pegasus *pegasus)
+{
+	int error;
+
+	guard(mutex)(&pegasus->pm_mutex);
+
+	pegasus->irq->dev = pegasus->usbdev;
+	if (usb_submit_urb(pegasus->irq, GFP_KERNEL))
+		return -EIO;
+
+	error = pegasus_set_mode(pegasus, PEN_MODE_XY, NOTETAKER_LED_MOUSE);
+	if (error) {
+		usb_kill_urb(pegasus->irq);
+		cancel_work_sync(&pegasus->init);
+		return error;
+	}
+
+	pegasus->is_open = true;
+
+	return 0;
+}
+
 static int pegasus_open(struct input_dev *dev)
 {
 	struct pegasus *pegasus = input_get_drvdata(dev);
@@ -223,39 +245,25 @@ static int pegasus_open(struct input_dev *dev)
 	if (error)
 		return error;
 
-	mutex_lock(&pegasus->pm_mutex);
-	pegasus->irq->dev = pegasus->usbdev;
-	if (usb_submit_urb(pegasus->irq, GFP_KERNEL)) {
-		error = -EIO;
-		goto err_autopm_put;
+	error = __pegasus_open(pegasus);
+	if (error) {
+		usb_autopm_put_interface(pegasus->intf);
+		return error;
 	}
 
-	error = pegasus_set_mode(pegasus, PEN_MODE_XY, NOTETAKER_LED_MOUSE);
-	if (error)
-		goto err_kill_urb;
-
-	pegasus->is_open = true;
-	mutex_unlock(&pegasus->pm_mutex);
 	return 0;
-
-err_kill_urb:
-	usb_kill_urb(pegasus->irq);
-	cancel_work_sync(&pegasus->init);
-err_autopm_put:
-	mutex_unlock(&pegasus->pm_mutex);
-	usb_autopm_put_interface(pegasus->intf);
-	return error;
 }
 
 static void pegasus_close(struct input_dev *dev)
 {
 	struct pegasus *pegasus = input_get_drvdata(dev);
 
-	mutex_lock(&pegasus->pm_mutex);
-	usb_kill_urb(pegasus->irq);
-	cancel_work_sync(&pegasus->init);
-	pegasus->is_open = false;
-	mutex_unlock(&pegasus->pm_mutex);
+	scoped_guard(mutex, &pegasus->pm_mutex) {
+		usb_kill_urb(pegasus->irq);
+		cancel_work_sync(&pegasus->init);
+
+		pegasus->is_open = false;
+	}
 
 	usb_autopm_put_interface(pegasus->intf);
 }
@@ -411,10 +419,10 @@ static int pegasus_suspend(struct usb_interface *intf, pm_message_t message)
 {
 	struct pegasus *pegasus = usb_get_intfdata(intf);
 
-	mutex_lock(&pegasus->pm_mutex);
+	guard(mutex)(&pegasus->pm_mutex);
+
 	usb_kill_urb(pegasus->irq);
 	cancel_work_sync(&pegasus->init);
-	mutex_unlock(&pegasus->pm_mutex);
 
 	return 0;
 }
@@ -422,31 +430,33 @@ static int pegasus_suspend(struct usb_interface *intf, pm_message_t message)
 static int pegasus_resume(struct usb_interface *intf)
 {
 	struct pegasus *pegasus = usb_get_intfdata(intf);
-	int retval = 0;
 
-	mutex_lock(&pegasus->pm_mutex);
+	guard(mutex)(&pegasus->pm_mutex);
+
 	if (pegasus->is_open && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
-		retval = -EIO;
-	mutex_unlock(&pegasus->pm_mutex);
+		return -EIO;
 
-	return retval;
+	return 0;
 }
 
 static int pegasus_reset_resume(struct usb_interface *intf)
 {
 	struct pegasus *pegasus = usb_get_intfdata(intf);
-	int retval = 0;
+	int error;
+
+	guard(mutex)(&pegasus->pm_mutex);
 
-	mutex_lock(&pegasus->pm_mutex);
 	if (pegasus->is_open) {
-		retval = pegasus_set_mode(pegasus, PEN_MODE_XY,
+		error = pegasus_set_mode(pegasus, PEN_MODE_XY,
 					  NOTETAKER_LED_MOUSE);
-		if (!retval && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
-			retval = -EIO;
+		if (error)
+			return error;
+
+		if (usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
+			return -EIO;
 	}
-	mutex_unlock(&pegasus->pm_mutex);
 
-	return retval;
+	return 0;
 }
 
 static const struct usb_device_id pegasus_ids[] = {