Message-ID: <a336a642-838c-48e9-aea3-703fd0d017bc@roeck-us.net>
Date: Thu, 22 Feb 2024 07:23:08 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Marek Behún <kabel@...nel.org>,
 linux-kernel@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
 Matti Vaittinen <mazziesaccount@...il.com>
Cc: Horia Geantă <horia.geanta@....com>,
 Pankaj Gupta <pankaj.gupta@....com>, Gaurav Jain <gaurav.jain@....com>,
 Herbert Xu <herbert@...dor.apana.org.au>,
 "David S. Miller" <davem@...emloft.net>, Davidlohr Bueso
 <dave@...olabs.net>, Jonathan Cameron <jonathan.cameron@...wei.com>,
 Dave Jiang <dave.jiang@...el.com>,
 Alison Schofield <alison.schofield@...el.com>,
 Vishal Verma <vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>,
 Dan Williams <dan.j.williams@...el.com>,
 Bamvor Jian Zhang <bamv2005@...il.com>,
 Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski
 <brgl@...ev.pl>, Douglas Anderson <dianders@...omium.org>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 James Seo <james@...iv.tech>, Jean Delvare <jdelvare@...e.com>,
 linux-crypto@...r.kernel.org, linux-cxl@...r.kernel.org,
 linux-gpio@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linux-hwmon@...r.kernel.org
Subject: Re: [PATCH 2/2] devm-helpers: Add resource managed version of debugfs
 directory create function

On 2/22/24 06:58, Marek Behún wrote:
> A few drivers register a devm action to remove a debugfs directory,
> implementing a one-liner function that calls debufs_remove_recursive().
> Help drivers avoid this repeated implementations by adding managed
> version of debugfs directory create function.
> 
> Use the new function devm_debugfs_create_dir() in the following
> drivers:
>    drivers/crypto/caam/ctrl.c
>    drivers/gpu/drm/bridge/ti-sn65dsi86.c
>    drivers/hwmon/hp-wmi-sensors.c
>    drivers/hwmon/mr75203.c
>    drivers/hwmon/pmbus/pmbus_core.c
> 
> Also use the action function devm_debugfs_dir_recursive_drop() in
> drivers
>    drivers/cxl/mem.c
>    drivers/gpio/gpio-mockup.c
> 
> Signed-off-by: Marek Behún <kabel@...nel.org>
> ---
>   drivers/crypto/caam/ctrl.c            | 16 +++------
>   drivers/cxl/mem.c                     |  9 ++---
>   drivers/gpio/gpio-mockup.c            | 11 ++----
>   drivers/gpu/drm/bridge/ti-sn65dsi86.c | 13 ++------
>   drivers/hwmon/hp-wmi-sensors.c        | 15 ++-------
>   drivers/hwmon/mr75203.c               | 15 +++------
>   drivers/hwmon/pmbus/pmbus_core.c      | 16 +++------
>   include/linux/devm-helpers.h          | 48 +++++++++++++++++++++++++++
>   8 files changed, 72 insertions(+), 71 deletions(-)
> 
> diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
> index bdf367f3f679..ea3ed9a17f1a 100644
> --- a/drivers/crypto/caam/ctrl.c
> +++ b/drivers/crypto/caam/ctrl.c
> @@ -7,6 +7,7 @@
>    */
>   
>   #include <linux/device.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/of_address.h>
>   #include <linux/of_irq.h>
>   #include <linux/platform_device.h>
> @@ -604,11 +605,6 @@ static int init_clocks(struct device *dev, const struct caam_imx_data *data)
>   	return devm_add_action_or_reset(dev, disable_clocks, ctrlpriv);
>   }
>   
> -static void caam_remove_debugfs(void *root)
> -{
> -	debugfs_remove_recursive(root);
> -}
> -
>   #ifdef CONFIG_FSL_MC_BUS
>   static bool check_version(struct fsl_mc_version *mc_version, u32 major,
>   			  u32 minor, u32 revision)
> @@ -1058,13 +1054,9 @@ static int caam_probe(struct platform_device *pdev)
>   	ctrlpriv->era = caam_get_era(perfmon);
>   	ctrlpriv->domain = iommu_get_domain_for_dev(dev);
>   
> -	dfs_root = debugfs_create_dir(dev_name(dev), NULL);
> -	if (IS_ENABLED(CONFIG_DEBUG_FS)) {
> -		ret = devm_add_action_or_reset(dev, caam_remove_debugfs,
> -					       dfs_root);
> -		if (ret)
> -			return ret;
> -	}
> +	dfs_root = devm_debugfs_create_dir(dev, dev_name(dev), NULL);
> +	if (IS_ERR(dfs_root))
> +		return PTR_ERR(dfs_root);
>   
>   	caam_debugfs_init(ctrlpriv, perfmon, dfs_root);
>   
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index c5c9d8e0d88d..4b38514887a4 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -2,6 +2,7 @@
>   /* Copyright(c) 2022 Intel Corporation. All rights reserved. */
>   #include <linux/debugfs.h>
>   #include <linux/device.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/module.h>
>   #include <linux/pci.h>
>   
> @@ -30,11 +31,6 @@ static void enable_suspend(void *data)
>   	cxl_mem_active_dec();
>   }
>   
> -static void remove_debugfs(void *dentry)
> -{
> -	debugfs_remove_recursive(dentry);
> -}
> -
>   static int cxl_mem_dpa_show(struct seq_file *file, void *data)
>   {
>   	struct device *dev = file->private;
> @@ -138,7 +134,8 @@ static int cxl_mem_probe(struct device *dev)
>   		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
>   				    &cxl_poison_clear_fops);
>   
> -	rc = devm_add_action_or_reset(dev, remove_debugfs, dentry);
> +	rc = devm_add_action_or_reset(dev, devm_debugfs_dir_recursive_drop,
> +				      dentry);
>   	if (rc)
>   		return rc;
>   
> diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
> index 455eecf6380e..adbe0fe09490 100644
> --- a/drivers/gpio/gpio-mockup.c
> +++ b/drivers/gpio/gpio-mockup.c
> @@ -12,6 +12,7 @@
>   #include <linux/cleanup.h>
>   #include <linux/debugfs.h>
>   #include <linux/device.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/gpio/driver.h>
>   #include <linux/interrupt.h>
>   #include <linux/irq.h>
> @@ -390,13 +391,6 @@ static void gpio_mockup_debugfs_setup(struct device *dev,
>   	}
>   }
>   
> -static void gpio_mockup_debugfs_cleanup(void *data)
> -{
> -	struct gpio_mockup_chip *chip = data;
> -
> -	debugfs_remove_recursive(chip->dbg_dir);
> -}
> -
>   static void gpio_mockup_dispose_mappings(void *data)
>   {
>   	struct gpio_mockup_chip *chip = data;
> @@ -480,7 +474,8 @@ static int gpio_mockup_probe(struct platform_device *pdev)
>   
>   	gpio_mockup_debugfs_setup(dev, chip);
>   
> -	return devm_add_action_or_reset(dev, gpio_mockup_debugfs_cleanup, chip);
> +	return devm_add_action_or_reset(dev, devm_debugfs_dir_recursive_drop,
> +					chip->dbg_dir);
>   }
>   
>   static const struct of_device_id gpio_mockup_of_match[] = {
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 62cc3893dca5..ad0ed2459394 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -10,6 +10,7 @@
>   #include <linux/bits.h>
>   #include <linux/clk.h>
>   #include <linux/debugfs.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/gpio/consumer.h>
>   #include <linux/gpio/driver.h>
>   #include <linux/i2c.h>
> @@ -427,18 +428,12 @@ static int status_show(struct seq_file *s, void *data)
>   
>   DEFINE_SHOW_ATTRIBUTE(status);
>   
> -static void ti_sn65dsi86_debugfs_remove(void *data)
> -{
> -	debugfs_remove_recursive(data);
> -}
> -
>   static void ti_sn65dsi86_debugfs_init(struct ti_sn65dsi86 *pdata)
>   {
>   	struct device *dev = pdata->dev;
>   	struct dentry *debugfs;
> -	int ret;
>   
> -	debugfs = debugfs_create_dir(dev_name(dev), NULL);
> +	debugfs = devm_debugfs_create_dir(dev, dev_name(dev), NULL);
>   
>   	/*
>   	 * We might get an error back if debugfs wasn't enabled in the kernel
> @@ -447,10 +442,6 @@ static void ti_sn65dsi86_debugfs_init(struct ti_sn65dsi86 *pdata)
>   	if (IS_ERR_OR_NULL(debugfs))
>   		return;
>   
> -	ret = devm_add_action_or_reset(dev, ti_sn65dsi86_debugfs_remove, debugfs);
> -	if (ret)
> -		return;
> -
>   	debugfs_create_file("status", 0600, debugfs, pdata, &status_fops);
>   }
>   
> diff --git a/drivers/hwmon/hp-wmi-sensors.c b/drivers/hwmon/hp-wmi-sensors.c
> index b5325d0e72b9..2a7c33763ce8 100644
> --- a/drivers/hwmon/hp-wmi-sensors.c
> +++ b/drivers/hwmon/hp-wmi-sensors.c
> @@ -23,6 +23,7 @@
>   
>   #include <linux/acpi.h>
>   #include <linux/debugfs.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/hwmon.h>
>   #include <linux/jiffies.h>
>   #include <linux/mutex.h>
> @@ -1304,12 +1305,6 @@ static int current_reading_show(struct seq_file *seqf, void *ignored)
>   }
>   DEFINE_SHOW_ATTRIBUTE(current_reading);
>   
> -/* hp_wmi_devm_debugfs_remove - devm callback for debugfs cleanup */
> -static void hp_wmi_devm_debugfs_remove(void *res)
> -{
> -	debugfs_remove_recursive(res);
> -}
> -
>   /* hp_wmi_debugfs_init - create and populate debugfs directory tree */
>   static void hp_wmi_debugfs_init(struct device *dev, struct hp_wmi_info *info,
>   				struct hp_wmi_platform_events *pevents,
> @@ -1320,21 +1315,15 @@ static void hp_wmi_debugfs_init(struct device *dev, struct hp_wmi_info *info,
>   	struct dentry *debugfs;
>   	struct dentry *entries;
>   	struct dentry *dir;
> -	int err;
>   	u8 i;
>   
>   	/* dev_name() gives a not-very-friendly GUID for WMI devices. */
>   	scnprintf(buf, sizeof(buf), "hp-wmi-sensors-%u", dev->id);
>   
> -	debugfs = debugfs_create_dir(buf, NULL);
> +	debugfs = devm_debugfs_create_dir(dev, buf, NULL);
>   	if (IS_ERR(debugfs))
>   		return;
>   
> -	err = devm_add_action_or_reset(dev, hp_wmi_devm_debugfs_remove,
> -				       debugfs);
> -	if (err)
> -		return;
> -
>   	entries = debugfs_create_dir("sensor", debugfs);
>   
>   	for (i = 0; i < icount; i++, info++) {
> diff --git a/drivers/hwmon/mr75203.c b/drivers/hwmon/mr75203.c
> index 50a8b9c3f94d..50f348fca108 100644
> --- a/drivers/hwmon/mr75203.c
> +++ b/drivers/hwmon/mr75203.c
> @@ -10,6 +10,7 @@
>   #include <linux/bits.h>
>   #include <linux/clk.h>
>   #include <linux/debugfs.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/hwmon.h>
>   #include <linux/kstrtox.h>
>   #include <linux/module.h>
> @@ -216,17 +217,11 @@ static const struct file_operations pvt_ts_coeff_j_fops = {
>   	.llseek = default_llseek,
>   };
>   
> -static void devm_pvt_ts_dbgfs_remove(void *data)
> -{
> -	struct pvt_device *pvt = (struct pvt_device *)data;
> -
> -	debugfs_remove_recursive(pvt->dbgfs_dir);
> -	pvt->dbgfs_dir = NULL;
> -}
> -
>   static int pvt_ts_dbgfs_create(struct pvt_device *pvt, struct device *dev)
>   {
> -	pvt->dbgfs_dir = debugfs_create_dir(dev_name(dev), NULL);
> +	pvt->dbgfs_dir = devm_debugfs_create_dir(dev, dev_name(dev), NULL);
> +	if (IS_ERR(pvt->dbgfs_dir))
> +		return PTR_ERR(pvt->dbgfs_dir);
>   
>   	debugfs_create_u32("ts_coeff_h", 0644, pvt->dbgfs_dir,
>   			   &pvt->ts_coeff.h);
> @@ -237,7 +232,7 @@ static int pvt_ts_dbgfs_create(struct pvt_device *pvt, struct device *dev)
>   	debugfs_create_file("ts_coeff_j", 0644, pvt->dbgfs_dir, pvt,
>   			    &pvt_ts_coeff_j_fops);
>   
> -	return devm_add_action_or_reset(dev, devm_pvt_ts_dbgfs_remove, pvt);
> +	return 0;
>   }
>   
>   static umode_t pvt_is_visible(const void *data, enum hwmon_sensor_types type,
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index 1363d9f89181..e0f956a21125 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -7,6 +7,7 @@
>    */
>   
>   #include <linux/debugfs.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/kernel.h>
>   #include <linux/math64.h>
>   #include <linux/module.h>
> @@ -3336,13 +3337,6 @@ static const struct file_operations pmbus_debugfs_ops_mfr = {
>   	.open = simple_open,
>   };
>   
> -static void pmbus_remove_debugfs(void *data)
> -{
> -	struct dentry *entry = data;
> -
> -	debugfs_remove_recursive(entry);
> -}
> -
>   static int pmbus_init_debugfs(struct i2c_client *client,
>   			      struct pmbus_data *data)
>   {
> @@ -3357,8 +3351,9 @@ static int pmbus_init_debugfs(struct i2c_client *client,
>   	 * Create the debugfs directory for this device. Use the hwmon device
>   	 * name to avoid conflicts (hwmon numbers are globally unique).
>   	 */
> -	data->debugfs = debugfs_create_dir(dev_name(data->hwmon_dev),
> -					   pmbus_debugfs_dir);
> +	data->debugfs = devm_debugfs_create_dir(data->dev,
> +						dev_name(data->hwmon_dev),
> +						pmbus_debugfs_dir);
>   	if (IS_ERR_OR_NULL(data->debugfs)) {
>   		data->debugfs = NULL;
>   		return -ENODEV;
> @@ -3542,8 +3537,7 @@ static int pmbus_init_debugfs(struct i2c_client *client,
>   		}
>   	}
>   
> -	return devm_add_action_or_reset(data->dev,
> -					pmbus_remove_debugfs, data->debugfs);
> +	return 0;
>   }
>   #else
>   static int pmbus_init_debugfs(struct i2c_client *client,
> diff --git a/include/linux/devm-helpers.h b/include/linux/devm-helpers.h
> index 70640fb96117..39d743175ec4 100644
> --- a/include/linux/devm-helpers.h
> +++ b/include/linux/devm-helpers.h
> @@ -23,6 +23,7 @@
>    * already ran.
>    */
>   
> +#include <linux/debugfs.h>
>   #include <linux/device.h>
>   #include <linux/kconfig.h>
>   #include <linux/mutex.h>
> @@ -108,4 +109,51 @@ static inline int devm_mutex_init(struct device *dev, struct mutex *lock)
>   		return 0;
>   }
>   
> +static inline void devm_debugfs_dir_recursive_drop(void *res)
> +{
> +	debugfs_remove_recursive(res);
> +}
> +
> +/**
> + * devm_debugfs_create_dir - Resource managed debugfs directory creation
> + * @dev:	Device which lifetime the directory is bound to
> + * @name:	a pointer to a string containing the name of the directory to
> + *		create
> + * @parent:	a pointer to the parent dentry for this file.  This should be a
> + *		directory dentry if set.  If this parameter is NULL, then the
> + *		directory will be created in the root of the debugfs filesystem.
> + *
> + * Create a debugfs directory which is automatically recursively removed when
> + * the driver is detached. A few drivers create debugfs directories which they
> + * want removed before driver is detached.
> + * devm_debugfs_create_dir() can be used to omit the explicit
> + * debugfs_remove_recursive() call when driver is detached.
> + */
> +static inline struct dentry *
> +devm_debugfs_create_dir(struct device *dev, const char *name,
> +			struct dentry *parent)
> +{
> +	struct dentry *dentry;
> +
> +	dentry = debugfs_create_dir(name, parent);
> +	if (IS_ERR(dentry))
> +		return dentry;
> +
> +	/*
> +	 * debugfs_remove_recursive() is an empty function if CONFIG_DEBUG_FS is
> +	 * disabled. No need to register an action in that case.
> +	 */
> +	if (IS_ENABLED(CONFIG_DEBUG_FS)) {


This conditional seems unnecessary since in that case debugfs_create_dir()
would return -ENODEV, and the code below would never be executed to start with.

Guenter

> +		int err;
> +
> +		err = devm_add_action_or_reset(dev,
> +					       devm_debugfs_dir_recursive_drop,
> +					       dentry);
> +		if (err < 0)
> +			return ERR_PTR(err);
> +	}
> +
> +	return dentry;
> +}
> +
>   #endif

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