linux-kernel - [PATCH 2/5] gpio: sysfs: use cleanup guards for the sysfs

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Message-Id: <20241024-gpio-notify-sysfs-v1-2-981f2773e785@linaro.org>
Date: Thu, 24 Oct 2024 13:32:45 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>, Kent Gibson <warthog618@...il.com>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH 2/5] gpio: sysfs: use cleanup guards for the sysfs_lock
 mutex

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

Shrink the code and remove some goto labels by using guards around the
sysfs_lock mutex. While at it: use __free(kfree) when allocating sysfs
callback data.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 64 ++++++++++++++++++--------------------------
 1 file changed, 26 insertions(+), 38 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 3ccb41a93ea7..096f79bbfe42 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -550,7 +550,6 @@ static const struct class gpio_class = {
 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 {
 	struct gpio_device *gdev;
-	struct gpiod_data *data;
 	struct device *dev;
 	int status;
 
@@ -574,24 +573,25 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 
 	gdev = desc->gdev;
 
-	mutex_lock(&sysfs_lock);
+	guard(mutex)(&sysfs_lock);
 
 	/* check if chip is being removed */
 	if (!gdev->mockdev) {
 		status = -ENODEV;
-		goto err_unlock;
+		goto err_clear_bit;
 	}
 
 	if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
 		gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
 		status = -EPERM;
-		goto err_unlock;
+		goto err_clear_bit;
 	}
 
-	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	struct gpiod_data *data __free(kfree) = kzalloc(sizeof(*data),
+							GFP_KERNEL);
 	if (!data) {
 		status = -ENOMEM;
-		goto err_unlock;
+		goto err_clear_bit;
 	}
 
 	data->desc = desc;
@@ -606,16 +606,13 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 					"gpio%u", desc_to_gpio(desc));
 	if (IS_ERR(dev)) {
 		status = PTR_ERR(dev);
-		goto err_free_data;
+		goto err_clear_bit;
 	}
 
-	mutex_unlock(&sysfs_lock);
+	data = NULL;
 	return 0;
 
-err_free_data:
-	kfree(data);
-err_unlock:
-	mutex_unlock(&sysfs_lock);
+err_clear_bit:
 	clear_bit(FLAG_EXPORT, &desc->flags);
 	gpiod_dbg(desc, "%s: status %d\n", __func__, status);
 	return status;
@@ -679,36 +676,28 @@ void gpiod_unexport(struct gpio_desc *desc)
 		return;
 	}
 
-	mutex_lock(&sysfs_lock);
+	scoped_guard(mutex, &sysfs_lock) {
+		if (!test_bit(FLAG_EXPORT, &desc->flags))
+			return;
 
-	if (!test_bit(FLAG_EXPORT, &desc->flags))
-		goto err_unlock;
+		dev = class_find_device(&gpio_class, NULL, desc, match_export);
+		if (!dev)
+			return;
 
-	dev = class_find_device(&gpio_class, NULL, desc, match_export);
-	if (!dev)
-		goto err_unlock;
+		data = dev_get_drvdata(dev);
+		clear_bit(FLAG_EXPORT, &desc->flags);
+		device_unregister(dev);
 
-	data = dev_get_drvdata(dev);
-
-	clear_bit(FLAG_EXPORT, &desc->flags);
-
-	device_unregister(dev);
-
-	/*
-	 * Release irq after deregistration to prevent race with edge_store.
-	 */
-	if (data->irq_flags)
-		gpio_sysfs_free_irq(dev);
-
-	mutex_unlock(&sysfs_lock);
+		/*
+		 * Release irq after deregistration to prevent race with
+		 * edge_store.
+		 */
+		if (data->irq_flags)
+			gpio_sysfs_free_irq(dev);
+	}
 
 	put_device(dev);
 	kfree(data);
-
-	return;
-
-err_unlock:
-	mutex_unlock(&sysfs_lock);
 }
 EXPORT_SYMBOL_GPL(gpiod_unexport);
 
@@ -749,9 +738,8 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 	if (IS_ERR(dev))
 		return PTR_ERR(dev);
 
-	mutex_lock(&sysfs_lock);
+	guard(mutex)(&sysfs_lock);
 	gdev->mockdev = dev;
-	mutex_unlock(&sysfs_lock);
 
 	return 0;
 }

-- 
2.45.2