diff mbox series

[v3,2/5] gpio: sysfs: use cleanup guards for the sysfs_lock mutex

Message ID 20241026-gpio-notify-sysfs-v3-2-ad8f127d12f5@linaro.org
State New
Headers show
Series gpio: sysfs: send character device notifications for sysfs class events | expand

Commit Message

Bartosz Golaszewski Oct. 26, 2024, 12:58 p.m. UTC 
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.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@linaro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 64 ++++++++++++++++++--------------------------
 1 file changed, 26 insertions(+), 38 deletions(-)

Comments

kernel test robot Oct. 27, 2024, 10:21 p.m. UTC | #1 
Hi Bartosz,

kernel test robot noticed the following build errors:

[auto build test ERROR on a39230ecf6b3057f5897bc4744a790070cfbe7a8]

url:    https://github.com/intel-lab-lkp/linux/commits/Bartosz-Golaszewski/gpio-sysfs-use-cleanup-guards-for-gpiod_data-mutex/20241026-210033
base:   a39230ecf6b3057f5897bc4744a790070cfbe7a8
patch link:    https://lore.kernel.org/r/20241026-gpio-notify-sysfs-v3-2-ad8f127d12f5%40linaro.org
patch subject: [PATCH v3 2/5] gpio: sysfs: use cleanup guards for the sysfs_lock mutex
config: i386-buildonly-randconfig-004-20241028 (https://download.01.org/0day-ci/archive/20241028/202410280514.EkyQpKfw-lkp@intel.com/config)
compiler: clang version 19.1.2 (https://github.com/llvm/llvm-project 7ba7d8e2f7b6445b60679da826210cdde29eaf8b)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241028/202410280514.EkyQpKfw-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410280514.EkyQpKfw-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/gpio/gpiolib-sysfs.c:588:3: error: cannot jump from this goto statement to its label
     588 |                 goto err_clear_bit;
         |                 ^
   drivers/gpio/gpiolib-sysfs.c:591:21: note: jump bypasses initialization of variable with __attribute__((cleanup))
     591 |         struct gpiod_data *data __free(kfree) = kzalloc(sizeof(*data),
         |                            ^
   drivers/gpio/gpiolib-sysfs.c:582:3: error: cannot jump from this goto statement to its label
     582 |                 goto err_clear_bit;
         |                 ^
   drivers/gpio/gpiolib-sysfs.c:591:21: note: jump bypasses initialization of variable with __attribute__((cleanup))
     591 |         struct gpiod_data *data __free(kfree) = kzalloc(sizeof(*data),
         |                            ^
   2 errors generated.


vim +588 drivers/gpio/gpiolib-sysfs.c

   534	
   535	/**
   536	 * gpiod_export - export a GPIO through sysfs
   537	 * @desc: GPIO to make available, already requested
   538	 * @direction_may_change: true if userspace may change GPIO direction
   539	 * Context: arch_initcall or later
   540	 *
   541	 * When drivers want to make a GPIO accessible to userspace after they
   542	 * have requested it -- perhaps while debugging, or as part of their
   543	 * public interface -- they may use this routine.  If the GPIO can
   544	 * change direction (some can't) and the caller allows it, userspace
   545	 * will see "direction" sysfs attribute which may be used to change
   546	 * the gpio's direction.  A "value" attribute will always be provided.
   547	 *
   548	 * Returns:
   549	 * 0 on success, or negative errno on failure.
   550	 */
   551	int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
   552	{
   553		struct gpio_device *gdev;
   554		struct device *dev;
   555		int status;
   556	
   557		/* can't export until sysfs is available ... */
   558		if (!class_is_registered(&gpio_class)) {
   559			pr_debug("%s: called too early!\n", __func__);
   560			return -ENOENT;
   561		}
   562	
   563		if (!desc) {
   564			pr_debug("%s: invalid gpio descriptor\n", __func__);
   565			return -EINVAL;
   566		}
   567	
   568		CLASS(gpio_chip_guard, guard)(desc);
   569		if (!guard.gc)
   570			return -ENODEV;
   571	
   572		if (test_and_set_bit(FLAG_EXPORT, &desc->flags))
   573			return -EPERM;
   574	
   575		gdev = desc->gdev;
   576	
   577		guard(mutex)(&sysfs_lock);
   578	
   579		/* check if chip is being removed */
   580		if (!gdev->mockdev) {
   581			status = -ENODEV;
   582			goto err_clear_bit;
   583		}
   584	
   585		if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
   586			gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
   587			status = -EPERM;
 > 588			goto err_clear_bit;
   589		}
   590	
   591		struct gpiod_data *data __free(kfree) = kzalloc(sizeof(*data),
   592								GFP_KERNEL);
   593		if (!data) {
   594			status = -ENOMEM;
   595			goto err_clear_bit;
   596		}
   597	
   598		data->desc = desc;
   599		mutex_init(&data->mutex);
   600		if (guard.gc->direction_input && guard.gc->direction_output)
   601			data->direction_can_change = direction_may_change;
   602		else
   603			data->direction_can_change = false;
   604	
   605		dev = device_create_with_groups(&gpio_class, &gdev->dev,
   606						MKDEV(0, 0), data, gpio_groups,
   607						"gpio%u", desc_to_gpio(desc));
   608		if (IS_ERR(dev)) {
   609			status = PTR_ERR(dev);
   610			goto err_clear_bit;
   611		}
   612	
   613		data = NULL;
   614		return 0;
   615	
   616	err_clear_bit:
   617		clear_bit(FLAG_EXPORT, &desc->flags);
   618		gpiod_dbg(desc, "%s: status %d\n", __func__, status);
   619		return status;
   620	}
   621	EXPORT_SYMBOL_GPL(gpiod_export);
   622
diff mbox series

Patch

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index a0926a1061ae..72617f929a2d 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -551,7 +551,6 @@  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;
 
@@ -575,24 +574,25 @@  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;
@@ -607,16 +607,13 @@  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;
@@ -680,36 +677,28 @@  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);
 
@@ -750,9 +739,8 @@  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;
 }