linux-kernel - [PATCH 1/6] Input: db9 - use guard notation when acquiring mutex

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Message-ID: <20240904043104.1030257-2-dmitry.torokhov@gmail.com>
Date: Tue,  3 Sep 2024 21:30:58 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: linux-input@...r.kernel.org
Cc: Erick Archer <erick.archer@...look.com>,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/6] Input: db9 - 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/joystick/db9.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/input/joystick/db9.c b/drivers/input/joystick/db9.c
index 682a29c27832..7ac0cfc3e786 100644
--- a/drivers/input/joystick/db9.c
+++ b/drivers/input/joystick/db9.c
@@ -505,24 +505,22 @@ static int db9_open(struct input_dev *dev)
 {
 	struct db9 *db9 = input_get_drvdata(dev);
 	struct parport *port = db9->pd->port;
-	int err;
 
-	err = mutex_lock_interruptible(&db9->mutex);
-	if (err)
-		return err;
-
-	if (!db9->used++) {
-		parport_claim(db9->pd);
-		parport_write_data(port, 0xff);
-		if (db9_modes[db9->mode].reverse) {
-			parport_data_reverse(port);
-			parport_write_control(port, DB9_NORMAL);
+	scoped_guard(mutex_intr, &db9->mutex) {
+		if (!db9->used++) {
+			parport_claim(db9->pd);
+			parport_write_data(port, 0xff);
+			if (db9_modes[db9->mode].reverse) {
+				parport_data_reverse(port);
+				parport_write_control(port, DB9_NORMAL);
+			}
+			mod_timer(&db9->timer, jiffies + DB9_REFRESH_TIME);
 		}
-		mod_timer(&db9->timer, jiffies + DB9_REFRESH_TIME);
+
+		return 0;
 	}
 
-	mutex_unlock(&db9->mutex);
-	return 0;
+	return -EINTR;
 }
 
 static void db9_close(struct input_dev *dev)
@@ -530,14 +528,14 @@ static void db9_close(struct input_dev *dev)
 	struct db9 *db9 = input_get_drvdata(dev);
 	struct parport *port = db9->pd->port;
 
-	mutex_lock(&db9->mutex);
+	guard(mutex)(&db9->mutex);
+
 	if (!--db9->used) {
 		del_timer_sync(&db9->timer);
 		parport_write_control(port, 0x00);
 		parport_data_forward(port);
 		parport_release(db9->pd);
 	}
-	mutex_unlock(&db9->mutex);
 }
 
 static void db9_attach(struct parport *pp)
-- 
2.46.0.469.g59c65b2a67-goog