Re: [PATCH v5 08/11] devm-helpers: Add resource managed version of debugfs directory create function

[Christophe JAILLET <christophe.jaillet@wanadoo.fr>]

Le 23/03/2024 à 17:43, Marek Behún a écrit :
> 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
> driver
>    drivers/gpio/gpio-mockup.c
> 
> As per Dan Williams' request [1], do not touch the driver
>    drivers/cxl/mem.c
> 
> [1] https://lore.kernel.org/linux-gpio/65d7918b358a5_1ee3129432@dwillia2-mobl3.amr.corp.intel.com.notmuch/
> 
> Signed-off-by: Marek Behún <kabel@kernel.org>
> ---
>   drivers/crypto/caam/ctrl.c            | 16 +++--------
>   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          | 40 +++++++++++++++++++++++++++
>   7 files changed, 61 insertions(+), 65 deletions(-)

...

> 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);

This look strange. Shouldn't the debugfs_create_dir() call in 
gpio_mockup_debugfs_setup() be changed, instead?

(I've not look in the previous version if something was said about it, 
so apologies if already discussed)

>   }
>   
>   static const struct of_device_id gpio_mockup_of_match[] = {

...


> 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);

Not sure if the test and error handling should be added here.
*If I'm correct*, functions related to debugfs already handle this case 
and just do nothing. And failure in debugfs related code is not 
considered as something that need to be reported and abort a probe function.

Maybe the same other (already existing) tests in this patch should be 
removed as well, in a separated patch.

just my 2c

CJ

>   
>   	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;
>   }

...