linux-kernel - Re: [PATCH 1/1] hwmon: remove unnecessary (void*) conversions

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Message-ID: <dada9a9c-32fd-9d8c-b692-5efb8a94c20f@gnuweeb.org>
Date:   Wed, 11 Jan 2023 13:09:35 +0700
From:   Ammar Faizi <ammarfaizi2@...weeb.org>
To:     XU pengfei <xupengfei@...china.com>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH 1/1] hwmon: remove unnecessary (void*) conversions

On 1/11/23 1:03 PM, Ammar Faizi wrote:
> On 1/11/23 10:29 AM, Guenter Roeck wrote:
>> On 1/10/23 18:07, XU pengfei wrote:
>>> diff --git a/drivers/hwmon/powr1220.c b/drivers/hwmon/powr1220.c
>>> index f77dc6db31ac..501337ee5aa3 100644
>>> --- a/drivers/hwmon/powr1220.c
>>> +++ b/drivers/hwmon/powr1220.c
>>> @@ -174,7 +174,7 @@ static umode_t
>>>   powr1220_is_visible(const void *data, enum hwmon_sensor_types type, u32
>>>               attr, int channel)
>>>   {
>>> -    struct powr1220_data *chip_data = (struct powr1220_data *)data;
>>> +    struct powr1220_data *chip_data = data;
> 
> This is wrong. That cast is needed to discard the "const".
> 
>    CC [M]  drivers/hwmon/powr1220.o
> drivers/hwmon/powr1220.c: In function ‘powr1220_is_visible’:
> drivers/hwmon/powr1220.c:177:43: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
>    177 |         struct powr1220_data *chip_data = data;
>        |                                           ^~~~
> cc1: all warnings being treated as errors

Anyway, powr1220_is_visible() doesn't write via that pointer, but
the local variable needs to be a const as well.

diff --git a/drivers/hwmon/powr1220.c b/drivers/hwmon/powr1220.c
index f77dc6db31ac..7cbbed5a6f5e 100644
--- a/drivers/hwmon/powr1220.c
+++ b/drivers/hwmon/powr1220.c
@@ -174,7 +174,7 @@ static umode_t
  powr1220_is_visible(const void *data, enum hwmon_sensor_types type, u32
                     attr, int channel)
  {
-       struct powr1220_data *chip_data = (struct powr1220_data *)data;
+       const struct powr1220_data *chip_data = data;
  
         if (channel >= chip_data->max_channels)
                 return 0;


-- 
Ammar Faizi