linux-kernel - [PATCH 17/22] Input: pegasus_notetaker - use guard notation when acquiring mutex

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Message-ID: <20240904044842.1048638-1-dmitry.torokhov@gmail.com>
Date: Tue,  3 Sep 2024 21:48:41 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: linux-input@...r.kernel.org
Cc: Michael Hennerich <michael.hennerich@...log.com>,
	Ville Syrjala <syrjala@....fi>,
	Support Opensource <support.opensource@...semi.com>,
	Eddie James <eajames@...ux.ibm.com>,
	Andrey Moiseev <o2g.org.ru@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Javier Carrasco <javier.carrasco.cruz@...il.com>,
	Jeff LaBundy <jeff@...undy.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 17/22] Input: pegasus_notetaker - 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.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 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..e1dc8365bfe9 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[] = {
-- 
2.46.0.469.g59c65b2a67-goog