linux-kernel - Re: [PATCH -next v2] hwmon: (smpro-hwmon) Improve switch statments in smpro_is

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Date:   Sat, 29 Oct 2022 15:49:24 +0700
From:   Quan Nguyen <quan@...amperecomputing.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Nathan Chancellor <nathan@...nel.org>
Cc:     Jean Delvare <jdelvare@...e.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        patches@...ts.linux.dev
Subject: Re: [PATCH -next v2] hwmon: (smpro-hwmon) Improve switch statments in
 smpro_is_visible()

Thanks Nathan for the fix.
- Quan

On 29/10/2022 01:14, Guenter Roeck wrote:
> On Thu, Oct 27, 2022 at 04:16:12PM -0700, Nathan Chancellor wrote:
>> Clang warns:
>>
>>    drivers/hwmon/smpro-hwmon.c:378:2: error: unannotated fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
>>            default:
>>            ^
>>    drivers/hwmon/smpro-hwmon.c:378:2: note: insert 'break;' to avoid fall-through
>>            default:
>>            ^
>>            break;
>>    1 error generated.
>>
>> Clang is a little more pedantic than GCC, which does not warn when
>> falling through to a case that is just break or return. Clang's version
>> is more in line with the kernel's own stance in deprecated.rst, which
>> states that all switch/case blocks must end in either break,
>> fallthrough, continue, goto, or return.
>>
>> Add the missing break to silence the warning. Additionally, adjust the
>> indentation of a break and add a default case to the inner switch
>> statement.
>>
>> Fixes: a87456864cbb ("hwmon: Add Ampere's Altra smpro-hwmon driver")
>> Link: https://github.com/ClangBuiltLinux/linux/issues/1751
>> Signed-off-by: Nathan Chancellor <nathan@...nel.org>
> 
> Applied.
> 
> Thanks,
> Guenter
> 
>> ---
>>
>> v2:
>>
>>      * Add missing default case to inner switch statement (Guenter)
>>      * Fix indentation of break in inner switch statement (Guenter)
>>      * Reword commit message to include these changes
>>
>> v1: https://lore.kernel.org/20221027195238.1789586-1-nathan@kernel.org/
>>
>>   drivers/hwmon/smpro-hwmon.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>>
>> base-commit: 0ffb687b6508c36a17b99bdaf014b38532404182
>>
>> diff --git a/drivers/hwmon/smpro-hwmon.c b/drivers/hwmon/smpro-hwmon.c
>> index ee54e21c2c12..a76c49dd8438 100644
>> --- a/drivers/hwmon/smpro-hwmon.c
>> +++ b/drivers/hwmon/smpro-hwmon.c
>> @@ -373,8 +373,11 @@ static umode_t smpro_is_visible(const void *data, enum hwmon_sensor_types type,
>>   			ret = regmap_read(hwmon->regmap, temperature[channel].reg, &value);
>>   			if (ret || value == 0xFFFF)
>>   				return 0;
>> -		break;
>> +			break;
>> +		default:
>> +			break;
>>   		}
>> +		break;
>>   	default:
>>   		break;
>>   	}