[PATCH 18/23] gpio: mockup: require debugfs to build

[Bartosz Golaszewski <brgl@xxxxxxxx>]

From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>

Debugfs has become the standard way of interfacing with gpio-mockup to
the point where the module is not very useful without it anymore. Let's
make it a hard requirement to build gpio-mockup.

Let's also add error checks whenever calling debugfs routines as we now
don't expect them to fail.

The device sub-directories must now be removed when the device is
detached to correctly support dynamically created chips.

The call to debugfs_remove_recursive() in module exit must be moved to
the bottom or we'd risk to remove the root directory before devices can
unregister their own sub-directories.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
---
 drivers/gpio/Kconfig       |  1 +
 drivers/gpio/gpio-mockup.c | 41 ++++++++++++++++++++++++++++----------
 2 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 8030fd91a3cc..515f345757d8 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1567,6 +1567,7 @@ config GPIO_AGGREGATOR
 
 config GPIO_MOCKUP
 	tristate "GPIO Testing Driver"
+	depends on DEBUG_FS
 	select IRQ_SIM
 	help
 	  This enables GPIO Testing driver, which provides a way to test GPIO
diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 29fbf007ab26..7df990662c17 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -348,38 +348,55 @@ static const struct file_operations gpio_mockup_debugfs_ops = {
 	.release = single_release,
 };
 
-static void gpio_mockup_debugfs_setup(struct device *dev,
-				      struct gpio_mockup_chip *chip)
+static void gpio_mockup_remove_chip_debugfs_entry(void *data)
+{
+	struct dentry *entry = data;
+
+	debugfs_remove_recursive(entry);
+}
+
+static int gpio_mockup_debugfs_setup(struct device *dev,
+				     struct gpio_mockup_chip *chip)
 {
 	struct gpio_mockup_dbgfs_private *priv;
 	struct gpio_chip *gc;
+	struct dentry *attr;
 	const char *devname;
 	char *name;
-	int i;
+	int i, ret;
 
 	gc = &chip->gc;
 	devname = dev_name(&gc->gpiodev->dev);
 
 	chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
+	if (IS_ERR(chip->dbg_dir))
+		return PTR_ERR(chip->dbg_dir);
+
+	ret = devm_add_action_or_reset(dev,
+			gpio_mockup_remove_chip_debugfs_entry, chip->dbg_dir);
+	if (ret)
+		return ret;
 
 	for (i = 0; i < gc->ngpio; i++) {
 		name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
 		if (!name)
-			return;
+			return -ENOMEM;
 
 		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 		if (!priv)
-			return;
+			return -ENOMEM;
 
 		priv->chip = chip;
 		priv->offset = i;
 		priv->desc = &gc->gpiodev->descs[i];
 
-		debugfs_create_file(name, 0200, chip->dbg_dir, priv,
-				    &gpio_mockup_debugfs_ops);
+		attr = debugfs_create_file(name, 0200, chip->dbg_dir, priv,
+					   &gpio_mockup_debugfs_ops);
+		if (IS_ERR(attr))
+			return PTR_ERR(attr);
 	}
 
-	return;
+	return 0;
 }
 
 static void gpio_mockup_dispose_mappings(void *data)
@@ -462,7 +479,9 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 	if (rv)
 		return rv;
 
-	gpio_mockup_debugfs_setup(dev, chip);
+	rv = gpio_mockup_debugfs_setup(dev, chip);
+	if (rv)
+		return rv;
 
 	return 0;
 }
@@ -629,6 +648,8 @@ static int __init gpio_mockup_init(void)
 	int ret;
 
 	gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
+	if (IS_ERR(gpio_mockup_dbg_dir))
+		return PTR_ERR(gpio_mockup_dbg_dir);
 
 	ret = platform_driver_register(&gpio_mockup_driver);
 	if (ret) {
@@ -650,9 +671,9 @@ static int __init gpio_mockup_init(void)
 
 static void __exit gpio_mockup_exit(void)
 {
-	debugfs_remove_recursive(gpio_mockup_dbg_dir);
 	platform_driver_unregister(&gpio_mockup_driver);
 	gpio_mockup_unregister_devices();
+	debugfs_remove_recursive(gpio_mockup_dbg_dir);
 }
 
 module_init(gpio_mockup_init);
-- 
2.26.1