linux-kernel - Re: [PATCH] drm/amd/pm: clean up redundant comparisons with 0

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Message-ID: <b15e6759f51beed255036b9b3c7c6740@foxhound.fi>
Date:   Wed, 08 Nov 2023 09:02:56 +0200
From:   José Pekkarinen <jose.pekkarinen@...hound.fi>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     evan.quan@....com, alexander.deucher@....com,
        christian.koenig@....com, Xinhui.Pan@....com,
        skhan@...uxfoundation.org, airlied@...il.com, daniel@...ll.ch,
        jdelvare@...e.com, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-kernel-mentees@...ts.linux.dev
Subject: Re: [PATCH] drm/amd/pm: clean up redundant comparisons with 0

On 2023-11-07 20:03, Guenter Roeck wrote:
> On 11/7/23 09:26, José Pekkarinen wrote:
>> On 2023-11-07 16:08, Guenter Roeck wrote:
>>> On 11/7/23 00:29, José Pekkarinen wrote:
>>>> There is a couple of function return checks of functions that return
>>>> unsigned values, and local variables to hold them are also unsigned, 
>>>> so
>>>> checking if they are negative will always return false. This patch 
>>>> will
>>>> remove them, as well as the never reached code.
>>>> 
>>>> drivers/gpu/drm/amd/pm/amdgpu_pm.c:2801:5-8: WARNING: Unsigned 
>>>> expression compared with zero: val < 0
>>>> drivers/gpu/drm/amd/pm/amdgpu_pm.c:2814:5-8: WARNING: Unsigned 
>>>> expression compared with zero: val < 0
>>>> 
>>>> Signed-off-by: José Pekkarinen <jose.pekkarinen@...hound.fi>
>>>> ---
>>>>   drivers/gpu/drm/amd/pm/amdgpu_pm.c | 4 ----
>>>>   1 file changed, 4 deletions(-)
>>>> 
>>>> diff --git a/drivers/gpu/drm/amd/pm/amdgpu_pm.c 
>>>> b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
>>>> index 8bb2da13826f..e7bb1d324084 100644
>>>> --- a/drivers/gpu/drm/amd/pm/amdgpu_pm.c
>>>> +++ b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
>>>> @@ -2798,8 +2798,6 @@ static ssize_t 
>>>> amdgpu_hwmon_show_power_avg(struct device *dev,
>>>>       unsigned int val;
>>>>         val = amdgpu_hwmon_get_power(dev, 
>>>> AMDGPU_PP_SENSOR_GPU_AVG_POWER);
>>>> -    if (val < 0)
>>>> -        return val;
>>>> 
>>> 
>>> This is reporting errors returned from amdgpu_hwmon_get_power() as
>>> large integers.
>> 
>>      Alright, that case it is a false positive, thanks for the 
>> comment!
>> 
> 
> 
> No, it isn't a false positive. The fix is wrong. The variable should be 
> declared
> 'int val', not 'unsigned int val'.

     Sorry I may have missunderstood your comment, I certainly can do the
minor fix then.

     Thanks!

     José.