linux-kernel - Re: [PATCH AUTOSEL 5.17 128/135] hwmon: Make chip parameter for with

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Message-ID: <dddc2b53-62eb-fda7-4425-afdd179a7037@roeck-us.net>
Date:   Mon, 30 May 2022 07:27:49 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     jdelvare@...e.com, corbet@....net, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.17 128/135] hwmon: Make chip parameter for
 with_info API mandatory

On 5/30/22 06:31, Sasha Levin wrote:
> From: Guenter Roeck <linux@...ck-us.net>
> 
> [ Upstream commit ddaefa209c4ac791c1262e97c9b2d0440c8ef1d5 ]
> 
> Various attempts were made recently to "convert" the old
> hwmon_device_register() API to devm_hwmon_device_register_with_info()
> by just changing the function name without actually converting the
> driver. Prevent this from happening by making the 'chip' parameter of
> devm_hwmon_device_register_with_info() mandatory.
> 
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> Signed-off-by: Sasha Levin <sashal@...nel.org>

This patch should not be backported. It is only relevant for new
kernel releases, and may have adverse affect if applied to older
kernels.

Guenter

> ---
>   Documentation/hwmon/hwmon-kernel-api.rst |  2 +-
>   drivers/hwmon/hwmon.c                    | 16 +++++++---------
>   2 files changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/hwmon/hwmon-kernel-api.rst b/Documentation/hwmon/hwmon-kernel-api.rst
> index c41eb6108103..23f27fe78e37 100644
> --- a/Documentation/hwmon/hwmon-kernel-api.rst
> +++ b/Documentation/hwmon/hwmon-kernel-api.rst
> @@ -72,7 +72,7 @@ hwmon_device_register_with_info is the most comprehensive and preferred means
>   to register a hardware monitoring device. It creates the standard sysfs
>   attributes in the hardware monitoring core, letting the driver focus on reading
>   from and writing to the chip instead of having to bother with sysfs attributes.
> -The parent device parameter cannot be NULL with non-NULL chip info. Its
> +The parent device parameter as well as the chip parameter must not be NULL. Its
>   parameters are described in more detail below.
>   
>   devm_hwmon_device_register_with_info is similar to
> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
> index 3ae961986fc3..55237a5fc49a 100644
> --- a/drivers/hwmon/hwmon.c
> +++ b/drivers/hwmon/hwmon.c
> @@ -854,11 +854,12 @@ EXPORT_SYMBOL_GPL(hwmon_device_register_with_groups);
>   
>   /**
>    * hwmon_device_register_with_info - register w/ hwmon
> - * @dev: the parent device
> - * @name: hwmon name attribute
> - * @drvdata: driver data to attach to created device
> - * @chip: pointer to hwmon chip information
> + * @dev: the parent device (mandatory)
> + * @name: hwmon name attribute (mandatory)
> + * @drvdata: driver data to attach to created device (optional)
> + * @chip: pointer to hwmon chip information (mandatory)
>    * @extra_groups: pointer to list of additional non-standard attribute groups
> + *	(optional)
>    *
>    * hwmon_device_unregister() must be called when the device is no
>    * longer needed.
> @@ -871,13 +872,10 @@ hwmon_device_register_with_info(struct device *dev, const char *name,
>   				const struct hwmon_chip_info *chip,
>   				const struct attribute_group **extra_groups)
>   {
> -	if (!name)
> -		return ERR_PTR(-EINVAL);
> -
> -	if (chip && (!chip->ops || !chip->ops->is_visible || !chip->info))
> +	if (!dev || !name || !chip)
>   		return ERR_PTR(-EINVAL);
>   
> -	if (chip && !dev)
> +	if (!chip->ops || !chip->ops->is_visible || !chip->info)
>   		return ERR_PTR(-EINVAL);
>   
>   	return __hwmon_device_register(dev, name, drvdata, chip, extra_groups);