linux-kernel - [PATCH] Input: psmouse-smbus - use guard notation when acquiring mutex

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Message-ID: <ZsrAa9XcDvHeIs9T@google.com>
Date: Sat, 24 Aug 2024 22:26:03 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Benjamin Tissoires <bentiss@...nel.org>
Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] Input: psmouse-smbus - use guard notation when acquiring
 mutex

This 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/mouse/psmouse-smbus.c | 28 ++++++++++------------------
 1 file changed, 10 insertions(+), 18 deletions(-)

diff --git a/drivers/input/mouse/psmouse-smbus.c b/drivers/input/mouse/psmouse-smbus.c
index 2a2459b1b4f2..93420f07b7d0 100644
--- a/drivers/input/mouse/psmouse-smbus.c
+++ b/drivers/input/mouse/psmouse-smbus.c
@@ -35,7 +35,7 @@ static void psmouse_smbus_check_adapter(struct i2c_adapter *adapter)
 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
 		return;
 
-	mutex_lock(&psmouse_smbus_mutex);
+	guard(mutex)(&psmouse_smbus_mutex);
 
 	list_for_each_entry(smbdev, &psmouse_smbus_list, node) {
 		if (smbdev->dead)
@@ -55,15 +55,13 @@ static void psmouse_smbus_check_adapter(struct i2c_adapter *adapter)
 			    "SMBus candidate adapter appeared, triggering rescan\n");
 		serio_rescan(smbdev->psmouse->ps2dev.serio);
 	}
-
-	mutex_unlock(&psmouse_smbus_mutex);
 }
 
 static void psmouse_smbus_detach_i2c_client(struct i2c_client *client)
 {
 	struct psmouse_smbus_dev *smbdev, *tmp;
 
-	mutex_lock(&psmouse_smbus_mutex);
+	guard(mutex)(&psmouse_smbus_mutex);
 
 	list_for_each_entry_safe(smbdev, tmp, &psmouse_smbus_list, node) {
 		if (smbdev->client != client)
@@ -85,8 +83,6 @@ static void psmouse_smbus_detach_i2c_client(struct i2c_client *client)
 			kfree(smbdev);
 		}
 	}
-
-	mutex_unlock(&psmouse_smbus_mutex);
 }
 
 static int psmouse_smbus_notifier_call(struct notifier_block *nb,
@@ -171,7 +167,7 @@ static void psmouse_smbus_disconnect(struct psmouse *psmouse)
 {
 	struct psmouse_smbus_dev *smbdev = psmouse->private;
 
-	mutex_lock(&psmouse_smbus_mutex);
+	guard(mutex)(&psmouse_smbus_mutex);
 
 	if (smbdev->dead) {
 		list_del(&smbdev->node);
@@ -186,8 +182,6 @@ static void psmouse_smbus_disconnect(struct psmouse *psmouse)
 		psmouse_smbus_schedule_remove(smbdev->client);
 	}
 
-	mutex_unlock(&psmouse_smbus_mutex);
-
 	psmouse->private = NULL;
 }
 
@@ -219,7 +213,7 @@ void psmouse_smbus_cleanup(struct psmouse *psmouse)
 {
 	struct psmouse_smbus_dev *smbdev, *tmp;
 
-	mutex_lock(&psmouse_smbus_mutex);
+	guard(mutex)(&psmouse_smbus_mutex);
 
 	list_for_each_entry_safe(smbdev, tmp, &psmouse_smbus_list, node) {
 		if (psmouse == smbdev->psmouse) {
@@ -227,8 +221,6 @@ void psmouse_smbus_cleanup(struct psmouse *psmouse)
 			kfree(smbdev);
 		}
 	}
-
-	mutex_unlock(&psmouse_smbus_mutex);
 }
 
 int psmouse_smbus_init(struct psmouse *psmouse,
@@ -267,9 +259,9 @@ int psmouse_smbus_init(struct psmouse *psmouse,
 	psmouse->disconnect = psmouse_smbus_disconnect;
 	psmouse->resync_time = 0;
 
-	mutex_lock(&psmouse_smbus_mutex);
-	list_add_tail(&smbdev->node, &psmouse_smbus_list);
-	mutex_unlock(&psmouse_smbus_mutex);
+	scoped_guard(mutex, &psmouse_smbus_mutex) {
+		list_add_tail(&smbdev->node, &psmouse_smbus_list);
+	}
 
 	/* Bind to already existing adapters right away */
 	error = i2c_for_each_dev(smbdev, psmouse_smbus_create_companion);
@@ -293,9 +285,9 @@ int psmouse_smbus_init(struct psmouse *psmouse,
 	smbdev->board.platform_data = NULL;
 
 	if (error < 0 || !leave_breadcrumbs) {
-		mutex_lock(&psmouse_smbus_mutex);
-		list_del(&smbdev->node);
-		mutex_unlock(&psmouse_smbus_mutex);
+		scoped_guard(mutex, &psmouse_smbus_mutex) {
+			list_del(&smbdev->node);
+		}
 
 		kfree(smbdev);
 	}
-- 
2.46.0.295.g3b9ea8a38a-goog


-- 
Dmitry