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From: Kent Gibson <warthog618@gmail.com>
To: linux-kernel@vger.kernel.org,
	linux-gpio@vger.kernel.org,
	brgl@bgdev.pl,
	linus.walleij@linaro.org,
	andy@kernel.org
Cc: Kent Gibson <warthog618@gmail.com>
Subject: [PATCH v3 4/5] gpiolib: cdev: fully adopt guard() and scoped_guard()
Date: Fri, 15 Dec 2023 10:38:04 +0800
Message-Id: <20231215023805.63289-5-warthog618@gmail.com>
In-Reply-To: <20231215023805.63289-1-warthog618@gmail.com>
References: <20231215023805.63289-1-warthog618@gmail.com>
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Use guard() or scoped_guard() for critical sections rather than
discrete lock/unlock pairs.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 drivers/gpio/gpiolib-cdev.c | 143 ++++++++++++++----------------------
 1 file changed, 57 insertions(+), 86 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index c140bcd63361..b956664f8649 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -737,13 +737,13 @@ static void linereq_put_event(struct linereq *lr,
 {
 	bool overflow = false;
 
-	spin_lock(&lr->wait.lock);
-	if (kfifo_is_full(&lr->events)) {
-		overflow = true;
-		kfifo_skip(&lr->events);
+	scoped_guard(spinlock, &lr->wait.lock) {
+		if (kfifo_is_full(&lr->events)) {
+			overflow = true;
+			kfifo_skip(&lr->events);
+		}
+		kfifo_in(&lr->events, le, 1);
 	}
-	kfifo_in(&lr->events, le, 1);
-	spin_unlock(&lr->wait.lock);
 	if (!overflow)
 		wake_up_poll(&lr->wait, EPOLLIN);
 	else
@@ -1476,18 +1476,13 @@ static long linereq_set_values_unlocked(struct linereq *lr,
 static long linereq_set_values(struct linereq *lr, void __user *ip)
 {
 	struct gpio_v2_line_values lv;
-	int ret;
 
 	if (copy_from_user(&lv, ip, sizeof(lv)))
 		return -EFAULT;
 
-	mutex_lock(&lr->config_mutex);
-
-	ret = linereq_set_values_unlocked(lr, &lv);
-
-	mutex_unlock(&lr->config_mutex);
+	guard(mutex)(&lr->config_mutex);
 
-	return ret;
+	return linereq_set_values_unlocked(lr, &lv);
 }
 
 static long linereq_set_config_unlocked(struct linereq *lr,
@@ -1545,13 +1540,9 @@ static long linereq_set_config(struct linereq *lr, void __user *ip)
 	if (ret)
 		return ret;
 
-	mutex_lock(&lr->config_mutex);
-
-	ret = linereq_set_config_unlocked(lr, &lc);
+	guard(mutex)(&lr->config_mutex);
 
-	mutex_unlock(&lr->config_mutex);
-
-	return ret;
+	return linereq_set_config_unlocked(lr, &lc);
 }
 
 static long linereq_ioctl_unlocked(struct file *file, unsigned int cmd,
@@ -1633,28 +1624,22 @@ static ssize_t linereq_read_unlocked(struct file *file, char __user *buf,
 		return -EINVAL;
 
 	do {
-		spin_lock(&lr->wait.lock);
-		if (kfifo_is_empty(&lr->events)) {
-			if (bytes_read) {
-				spin_unlock(&lr->wait.lock);
-				return bytes_read;
+		scoped_guard(spinlock, &lr->wait.lock) {
+			if (kfifo_is_empty(&lr->events)) {
+				if (bytes_read)
+					return bytes_read;
+
+				if (file->f_flags & O_NONBLOCK)
+					return -EAGAIN;
+
+				ret = wait_event_interruptible_locked(lr->wait,
+						!kfifo_is_empty(&lr->events));
+				if (ret)
+					return ret;
 			}
 
-			if (file->f_flags & O_NONBLOCK) {
-				spin_unlock(&lr->wait.lock);
-				return -EAGAIN;
-			}
-
-			ret = wait_event_interruptible_locked(lr->wait,
-					!kfifo_is_empty(&lr->events));
-			if (ret) {
-				spin_unlock(&lr->wait.lock);
-				return ret;
-			}
+			ret = kfifo_out(&lr->events, &le, 1);
 		}
-
-		ret = kfifo_out(&lr->events, &le, 1);
-		spin_unlock(&lr->wait.lock);
 		if (ret != 1) {
 			/*
 			 * This should never happen - we were holding the
@@ -2004,28 +1989,22 @@ static ssize_t lineevent_read_unlocked(struct file *file, char __user *buf,
 		return -EINVAL;
 
 	do {
-		spin_lock(&le->wait.lock);
-		if (kfifo_is_empty(&le->events)) {
-			if (bytes_read) {
-				spin_unlock(&le->wait.lock);
-				return bytes_read;
-			}
-
-			if (file->f_flags & O_NONBLOCK) {
-				spin_unlock(&le->wait.lock);
-				return -EAGAIN;
+		scoped_guard(spinlock, &le->wait.lock) {
+			if (kfifo_is_empty(&le->events)) {
+				if (bytes_read)
+					return bytes_read;
+
+				if (file->f_flags & O_NONBLOCK)
+					return -EAGAIN;
+
+				ret = wait_event_interruptible_locked(le->wait,
+						!kfifo_is_empty(&le->events));
+				if (ret)
+					return ret;
 			}
 
-			ret = wait_event_interruptible_locked(le->wait,
-					!kfifo_is_empty(&le->events));
-			if (ret) {
-				spin_unlock(&le->wait.lock);
-				return ret;
-			}
+			ret = kfifo_out(&le->events, &ge, 1);
 		}
-
-		ret = kfifo_out(&le->events, &ge, 1);
-		spin_unlock(&le->wait.lock);
 		if (ret != 1) {
 			/*
 			 * This should never happen - we were holding the lock
@@ -2719,38 +2698,30 @@ static ssize_t lineinfo_watch_read_unlocked(struct file *file, char __user *buf,
 #endif
 
 	do {
-		spin_lock(&cdev->wait.lock);
-		if (kfifo_is_empty(&cdev->events)) {
-			if (bytes_read) {
-				spin_unlock(&cdev->wait.lock);
-				return bytes_read;
-			}
-
-			if (file->f_flags & O_NONBLOCK) {
-				spin_unlock(&cdev->wait.lock);
-				return -EAGAIN;
-			}
-
-			ret = wait_event_interruptible_locked(cdev->wait,
-					!kfifo_is_empty(&cdev->events));
-			if (ret) {
-				spin_unlock(&cdev->wait.lock);
-				return ret;
+		scoped_guard(spinlock, &cdev->wait.lock) {
+			if (kfifo_is_empty(&cdev->events)) {
+				if (bytes_read)
+					return bytes_read;
+
+				if (file->f_flags & O_NONBLOCK)
+					return -EAGAIN;
+
+				ret = wait_event_interruptible_locked(cdev->wait,
+						!kfifo_is_empty(&cdev->events));
+				if (ret)
+					return ret;
 			}
-		}
 #ifdef CONFIG_GPIO_CDEV_V1
-		/* must be after kfifo check so watch_abi_version is set */
-		if (atomic_read(&cdev->watch_abi_version) == 2)
-			event_size = sizeof(struct gpio_v2_line_info_changed);
-		else
-			event_size = sizeof(struct gpioline_info_changed);
-		if (count < event_size) {
-			spin_unlock(&cdev->wait.lock);
-			return -EINVAL;
-		}
+			/* must be after kfifo check so watch_abi_version is set */
+			if (atomic_read(&cdev->watch_abi_version) == 2)
+				event_size = sizeof(struct gpio_v2_line_info_changed);
+			else
+				event_size = sizeof(struct gpioline_info_changed);
+			if (count < event_size)
+				return -EINVAL;
 #endif
-		ret = kfifo_out(&cdev->events, &event, 1);
-		spin_unlock(&cdev->wait.lock);
+			ret = kfifo_out(&cdev->events, &event, 1);
+		}
 		if (ret != 1) {
 			ret = -EIO;
 			break;
-- 
2.39.2