[PATCH] drm/amd/powerplay: Fix uninitialized warning in arcturus ppt driver

[Nirmoy]

On 8/12/20 2:43 PM, StDenis, Tom wrote:
> [AMD Official Use Only - Internal Distribution Only]
>
> Possibly, but since the arcturus_get_smu_metrics_data() can error out we should check that return value no?


Yes, we need that return check.

>
> (also setting *value to 0 avoids this bug in the future...).


I think caller should initialize the result value before passing it to 
arcturus_get_smu_metrics_data

as the warning is generated from the calling function. My comment is 
only concerning about setting "value"

to 0, which seems wrong. Rest of the patch is fine.


Nirmoy


>
> Tom
>
> ________________________________________
> From: Das, Nirmoy <Nirmoy.Das at amd.com>
> Sent: Wednesday, August 12, 2020 08:40
> To: StDenis, Tom; amd-gfx at lists.freedesktop.org
> Subject: Re: [PATCH] drm/amd/powerplay: Fix uninitialized warning in arcturus ppt driver
>
>
> On 8/12/20 2:20 PM, Tom St Denis wrote:
>> Fixes:
>>
>>     CC [M]  drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_mst_types.o
>> drivers/gpu/drm/amd/amdgpu/../powerplay/arcturus_ppt.c: In function ‘arcturus_log_thermal_throttling_event’:
>> drivers/gpu/drm/amd/amdgpu/../powerplay/arcturus_ppt.c:2223:24: warning: ‘throttler_status’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>>    2223 |   if (throttler_status & logging_label[throttler_idx].feature_mask) {
>>
>> by making arcturus_get_smu_metrics_data() assign a default value
>> (of zero) before any possible return point as well as simply error
>> out of arcturus_log_thermal_throttling_event() if it fails.
>>
>> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
>> ---
>>    drivers/gpu/drm/amd/powerplay/arcturus_ppt.c | 12 ++++++++++--
>>    1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/powerplay/arcturus_ppt.c b/drivers/gpu/drm/amd/powerplay/arcturus_ppt.c
>> index 8b1025dc54fd..78f7ec95e4f5 100644
>> --- a/drivers/gpu/drm/amd/powerplay/arcturus_ppt.c
>> +++ b/drivers/gpu/drm/amd/powerplay/arcturus_ppt.c
>> @@ -551,6 +551,9 @@ static int arcturus_get_smu_metrics_data(struct smu_context *smu,
>>
>>        mutex_lock(&smu->metrics_lock);
>>
>> +     // assign default value
>> +     *value = 0;
>> +
>>        ret = smu_cmn_get_metrics_table_locked(smu,
>>                                               NULL,
>>                                               false);
>> @@ -2208,15 +2211,20 @@ static const struct throttling_logging_label {
>>    };
>>    static void arcturus_log_thermal_throttling_event(struct smu_context *smu)
>>    {
>> -     int throttler_idx, throtting_events = 0, buf_idx = 0;
>> +     int throttler_idx, throtting_events = 0, buf_idx = 0, ret;
>>        struct amdgpu_device *adev = smu->adev;
>>        uint32_t throttler_status;
>
> I think initializing throttler_status here should resolve the warning.
>
>>        char log_buf[256];
>>
>> -     arcturus_get_smu_metrics_data(smu,
>> +     ret = arcturus_get_smu_metrics_data(smu,
>>                                      METRICS_THROTTLER_STATUS,
>>                                      &throttler_status);
>>
>> +     if (ret) {
>> +             dev_err(adev->dev, "Could not read from arcturus_get_smu_metrics_data()\n");
>> +             return;
>> +     }
>> +
>>        memset(log_buf, 0, sizeof(log_buf));
>>        for (throttler_idx = 0; throttler_idx < ARRAY_SIZE(logging_label);
>>             throttler_idx++) {