linux-kernel - [PATCH 03/17] Input: atkbd - use guard notation when acquiring mutex

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Message-ID: <20240825051627.2848495-4-dmitry.torokhov@gmail.com>
Date: Sat, 24 Aug 2024 22:16:07 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: linux-input@...r.kernel.org
Cc: Michael Hennerich <michael.hennerich@...log.com>,
	Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>,
	Laxman Dewangan <ldewangan@...dia.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Tony Lindgren <tony@...mide.com>,
	Jeff LaBundy <jeff@...undy.com>,
	linux-kernel@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-tegra@...r.kernel.org
Subject: [PATCH 03/17] Input: atkbd - 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/keyboard/atkbd.c | 37 ++++++++++++++--------------------
 1 file changed, 15 insertions(+), 22 deletions(-)

diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
index f4f2078cf501..5855d4fc6e6a 100644
--- a/drivers/input/keyboard/atkbd.c
+++ b/drivers/input/keyboard/atkbd.c
@@ -639,7 +639,7 @@ static void atkbd_event_work(struct work_struct *work)
 {
 	struct atkbd *atkbd = container_of(work, struct atkbd, event_work.work);
 
-	mutex_lock(&atkbd->mutex);
+	guard(mutex)(&atkbd->mutex);
 
 	if (!atkbd->enabled) {
 		/*
@@ -657,8 +657,6 @@ static void atkbd_event_work(struct work_struct *work)
 		if (test_and_clear_bit(ATKBD_REP_EVENT_BIT, &atkbd->event_mask))
 			atkbd_set_repeat_rate(atkbd);
 	}
-
-	mutex_unlock(&atkbd->mutex);
 }
 
 /*
@@ -1361,7 +1359,7 @@ static int atkbd_reconnect(struct serio *serio)
 {
 	struct atkbd *atkbd = atkbd_from_serio(serio);
 	struct serio_driver *drv = serio->drv;
-	int retval = -1;
+	int error;
 
 	if (!atkbd || !drv) {
 		dev_dbg(&serio->dev,
@@ -1369,16 +1367,17 @@ static int atkbd_reconnect(struct serio *serio)
 		return -1;
 	}
 
-	mutex_lock(&atkbd->mutex);
+	guard(mutex)(&atkbd->mutex);
 
 	atkbd_disable(atkbd);
 
 	if (atkbd->write) {
-		if (atkbd_probe(atkbd))
-			goto out;
+		error = atkbd_probe(atkbd);
+		if (error)
+			return error;
 
 		if (atkbd->set != atkbd_select_set(atkbd, atkbd->set, atkbd->extra))
-			goto out;
+			return -EIO;
 
 		/*
 		 * Restore LED state and repeat rate. While input core
@@ -1404,11 +1403,7 @@ static int atkbd_reconnect(struct serio *serio)
 	if (atkbd->write)
 		atkbd_activate(atkbd);
 
-	retval = 0;
-
- out:
-	mutex_unlock(&atkbd->mutex);
-	return retval;
+	return 0;
 }
 
 static const struct serio_device_id atkbd_serio_ids[] = {
@@ -1465,17 +1460,15 @@ static ssize_t atkbd_attr_set_helper(struct device *dev, const char *buf, size_t
 	struct atkbd *atkbd = atkbd_from_serio(serio);
 	int retval;
 
-	retval = mutex_lock_interruptible(&atkbd->mutex);
-	if (retval)
-		return retval;
+	scoped_guard(mutex_intr, &atkbd->mutex) {
+		atkbd_disable(atkbd);
+		retval = handler(atkbd, buf, count);
+		atkbd_enable(atkbd);
 
-	atkbd_disable(atkbd);
-	retval = handler(atkbd, buf, count);
-	atkbd_enable(atkbd);
-
-	mutex_unlock(&atkbd->mutex);
+		return retval;
+	}
 
-	return retval;
+	return -EINTR;
 }
 
 static ssize_t atkbd_show_extra(struct atkbd *atkbd, char *buf)
-- 
2.46.0.295.g3b9ea8a38a-goog