linux-kernel - [PATCH v3] Input: pxrc - simplify mutex handling with guard macro

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Date:   Sat, 02 Dec 2023 17:59:48 +0100
From:   Marcus Folkesson <marcus.folkesson@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Marcus Folkesson <marcus.folkesson@...il.com>
Subject: [PATCH v3] Input: pxrc - simplify mutex handling with guard macro

Use the guard(mutex) macro for handle mutex lock/unlocks.

Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
---
Changes in v3:
- Rename retval->error in pxrc_open() as it now only holds error code
- Return early instead of assign retval in pxrc_resume()
- Link to v2: https://lore.kernel.org/r/20231201-pxrc-guard-v2-1-714779672bc8@gmail.com

Changes in v2:
- Add guard in pxrc_open()
- Link to v1: https://lore.kernel.org/r/20231201-pxrc-guard-v1-1-38937e657368@gmail.com
---
 drivers/input/joystick/pxrc.c | 42 ++++++++++++++++++------------------------
 1 file changed, 18 insertions(+), 24 deletions(-)

diff --git a/drivers/input/joystick/pxrc.c b/drivers/input/joystick/pxrc.c
index ea2bf5951d67..52d9eab667b7 100644
--- a/drivers/input/joystick/pxrc.c
+++ b/drivers/input/joystick/pxrc.c
@@ -5,15 +5,17 @@
  * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@...il.com>
  */
 
-#include <linux/kernel.h>
+#include <linux/cleanup.h>
 #include <linux/errno.h>
-#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
 #include <linux/uaccess.h>
+
 #include <linux/usb.h>
 #include <linux/usb/input.h>
-#include <linux/mutex.h>
-#include <linux/input.h>
 
 #define PXRC_VENDOR_ID		0x1781
 #define PXRC_PRODUCT_ID		0x0898
@@ -81,33 +83,28 @@ static void pxrc_usb_irq(struct urb *urb)
 static int pxrc_open(struct input_dev *input)
 {
 	struct pxrc *pxrc = input_get_drvdata(input);
-	int retval;
+	int error;
 
-	mutex_lock(&pxrc->pm_mutex);
-	retval = usb_submit_urb(pxrc->urb, GFP_KERNEL);
-	if (retval) {
+	guard(mutex)(&pxrc->pm_mutex);
+	error = usb_submit_urb(pxrc->urb, GFP_KERNEL);
+	if (error) {
 		dev_err(&pxrc->intf->dev,
 			"%s - usb_submit_urb failed, error: %d\n",
-			__func__, retval);
-		retval = -EIO;
-		goto out;
+			__func__, error);
+		return -EIO;
 	}
 
 	pxrc->is_open = true;
-
-out:
-	mutex_unlock(&pxrc->pm_mutex);
-	return retval;
+	return 0;
 }
 
 static void pxrc_close(struct input_dev *input)
 {
 	struct pxrc *pxrc = input_get_drvdata(input);
 
-	mutex_lock(&pxrc->pm_mutex);
+	guard(mutex)(&pxrc->pm_mutex);
 	usb_kill_urb(pxrc->urb);
 	pxrc->is_open = false;
-	mutex_unlock(&pxrc->pm_mutex);
 }
 
 static void pxrc_free_urb(void *_pxrc)
@@ -208,10 +205,9 @@ static int pxrc_suspend(struct usb_interface *intf, pm_message_t message)
 {
 	struct pxrc *pxrc = usb_get_intfdata(intf);
 
-	mutex_lock(&pxrc->pm_mutex);
+	guard(mutex)(&pxrc->pm_mutex);
 	if (pxrc->is_open)
 		usb_kill_urb(pxrc->urb);
-	mutex_unlock(&pxrc->pm_mutex);
 
 	return 0;
 }
@@ -219,14 +215,12 @@ static int pxrc_suspend(struct usb_interface *intf, pm_message_t message)
 static int pxrc_resume(struct usb_interface *intf)
 {
 	struct pxrc *pxrc = usb_get_intfdata(intf);
-	int retval = 0;
 
-	mutex_lock(&pxrc->pm_mutex);
+	guard(mutex)(&pxrc->pm_mutex);
 	if (pxrc->is_open && usb_submit_urb(pxrc->urb, GFP_KERNEL) < 0)
-		retval = -EIO;
+		return -EIO;
 
-	mutex_unlock(&pxrc->pm_mutex);
-	return retval;
+	return 0;
 }
 
 static int pxrc_pre_reset(struct usb_interface *intf)

---
base-commit: ffc253263a1375a65fa6c9f62a893e9767fbebfa
change-id: 20231201-pxrc-guard-03dc35771b36

Best regards,
-- 
Marcus Folkesson <marcus.folkesson@...il.com>