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Message-ID: <25517c15-30f6-fbc5-5731-44c41ef904c7@roeck-us.net>
Date:   Mon, 4 Apr 2022 16:31:08 -0700
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To:     Tom Rix <trix@redhat.com>, Michael Walle <michael@walle.cc>,
        Xu Yilun <yilun.xu@intel.com>,
        Jean Delvare <jdelvare@suse.com>, Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
Cc:     linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, David Laight <David.Laight@ACULAB.COM>
References: <20220404184340.3973329-1-michael@walle.cc>
 <20220404184340.3973329-2-michael@walle.cc>
 <428c28e4-87cc-50a4-ef13-41ae36702a84@redhat.com>
From:   Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH v3 1/2] hwmon: introduce hwmon_sanitize_name()
In-Reply-To: <428c28e4-87cc-50a4-ef13-41ae36702a84@redhat.com>
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On 4/4/22 16:14, Tom Rix wrote:
> 
> On 4/4/22 11:43 AM, Michael Walle wrote:
>> More and more drivers will check for bad characters in the hwmon name
>> and all are using the same code snippet. Consolidate that code by adding
>> a new hwmon_sanitize_name() function.
>>
>> Signed-off-by: Michael Walle <michael@walle.cc>
>> ---
>>   Documentation/hwmon/hwmon-kernel-api.rst | 16 ++++++++
>>   drivers/hwmon/hwmon.c                    | 50 ++++++++++++++++++++++++
>>   include/linux/hwmon.h                    |  3 ++
>>   3 files changed, 69 insertions(+)
>>
>> diff --git a/Documentation/hwmon/hwmon-kernel-api.rst b/Documentation/hwmon/hwmon-kernel-api.rst
>> index c41eb6108103..e2975d5caf34 100644
>> --- a/Documentation/hwmon/hwmon-kernel-api.rst
>> +++ b/Documentation/hwmon/hwmon-kernel-api.rst
>> @@ -50,6 +50,10 @@ register/unregister functions::
>>     void devm_hwmon_device_unregister(struct device *dev);
>> +  char *hwmon_sanitize_name(const char *name);
>> +
>> +  char *devm_hwmon_sanitize_name(struct device *dev, const char *name);
>> +
>>   hwmon_device_register_with_groups registers a hardware monitoring device.
>>   The first parameter of this function is a pointer to the parent device.
>>   The name parameter is a pointer to the hwmon device name. The registration
>> @@ -95,6 +99,18 @@ All supported hwmon device registration functions only accept valid device
>>   names. Device names including invalid characters (whitespace, '*', or '-')
>>   will be rejected. The 'name' parameter is mandatory.
>> +If the driver doesn't use a static device name (for example it uses
>> +dev_name()), and therefore cannot make sure the name only contains valid
>> +characters, hwmon_sanitize_name can be used. This convenience function
>> +will duplicate the string and replace any invalid characters with an
>> +underscore. It will allocate memory for the new string and it is the
>> +responsibility of the caller to release the memory when the device is
>> +removed.
>> +
>> +devm_hwmon_sanitize_name is the resource managed version of
>> +hwmon_sanitize_name; the memory will be freed automatically on device
>> +removal.
>> +
>>   Using devm_hwmon_device_register_with_info()
>>   --------------------------------------------
>> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
>> index 989e2c8496dd..cc4a16a466a0 100644
>> --- a/drivers/hwmon/hwmon.c
>> +++ b/drivers/hwmon/hwmon.c
>> @@ -1057,6 +1057,56 @@ void devm_hwmon_device_unregister(struct device *dev)
>>   }
>>   EXPORT_SYMBOL_GPL(devm_hwmon_device_unregister);
>> +static char *__hwmon_sanitize_name(struct device *dev, const char *old_name)
>> +{
>> +    char *name, *p;
>> +
>> +    if (dev)
>> +        name = devm_kstrdup(dev, old_name, GFP_KERNEL);
>> +    else
>> +        name = kstrdup(old_name, GFP_KERNEL);
>> +    if (!name)
>> +        return NULL;
> should return ERR_PTR(-ENOMEM)

In general this is a matter of opinion, but other hwmon functions
return  ERR_PTR(-ENOMEM), so I agree here.

>> +
>> +    for (p = name; *p; p++)
>> +        if (hwmon_is_bad_char(*p))
>> +            *p = '_';
>> +
>> +    return name;
>> +}
>> +
>> +/**
>> + * hwmon_sanitize_name - Replaces invalid characters in a hwmon name
>> + * @name: NUL-terminated name
>> + *
>> + * Allocates a new string where any invalid characters will be replaced
>> + * by an underscore. It is the responsibility of the caller to release
>> + * the memory.
>> + *
>> + * Returns newly allocated name or %NULL in case of error.
>> + */
>> +char *hwmon_sanitize_name(const char *name)
>> +{
>> +    return __hwmon_sanitize_name(NULL, name);
>> +}
>> +EXPORT_SYMBOL_GPL(hwmon_sanitize_name);
>> +
>> +/**
>> + * devm_hwmon_sanitize_name - resource managed hwmon_sanitize_name()
>> + * @dev: device to allocate memory for
>> + * @name: NUL-terminated name
>> + *
>> + * Allocates a new string where any invalid characters will be replaced
>> + * by an underscore.
>> + *
>> + * Returns newly allocated name or %NULL in case of error.
>> + */
>> +char *devm_hwmon_sanitize_name(struct device *dev, const char *name)
>> +{
>> +    return __hwmon_sanitize_name(dev, name);
> Should have a (!dev) check.

... and return ERR_PTR(-EINVAL) if it is NULL, to match
hwmon registration functions.

>> +}
>> +EXPORT_SYMBOL_GPL(devm_hwmon_sanitize_name);
>> +
>>   static void __init hwmon_pci_quirks(void)
>>   {
>>   #if defined CONFIG_X86 && defined CONFIG_PCI
>> diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
>> index eba380b76d15..4efaf06fd2b8 100644
>> --- a/include/linux/hwmon.h
>> +++ b/include/linux/hwmon.h
>> @@ -461,6 +461,9 @@ void devm_hwmon_device_unregister(struct device *dev);
>>   int hwmon_notify_event(struct device *dev, enum hwmon_sensor_types type,
>>                  u32 attr, int channel);
>> +char *hwmon_sanitize_name(const char *name);
>> +char *devm_hwmon_sanitize_name(struct device *dev, const char *name);
>> +
>>   /**
>>    * hwmon_is_bad_char - Is the char invalid in a hwmon name
> 
> This still needed in *.h ?
> 

Yes, because it is used by out-of-tree drivers. We can only move
that into hwmon.c after all users are gone.

Guenter