Re: [PATCH v2 04/10] drm/amd/display: use eld_mutex to protect access to connector->eld

[Harry Wentland]

On 2024-12-10 16:20, Dmitry Baryshkov wrote:
> On Fri, Dec 06, 2024 at 11:43:07AM +0200, Dmitry Baryshkov wrote:
>> Reading access to connector->eld can happen at the same time the
>> drm_edid_to_eld() updates the data. Take the newly added eld_mutex in
>> order to protect connector->eld from concurrent access.
>>
>> Reviewed-by: Maxime Ripard <mripard@xxxxxxxxxx>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
>> ---
>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 ++
>>  1 file changed, 2 insertions(+)
> 
> Harry, Leo, Rodrigo, Alex, Christian, Xinhui, any response to this one
> and to the radeon patches? I'd like to be able to pick the series for
> drm-misc and these two are not reviewed by you.
> 
>>
>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> index 19a58630e774029767bf2a27eb4ddf17e3c21129..04c68c320252b5ce9647f0606fb86fe57f347639 100644
>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> @@ -1037,8 +1037,10 @@ static int amdgpu_dm_audio_component_get_eld(struct device *kdev, int port,
>>  			continue;
>>  
>>  		*enabled = true;
>> +		mutex_lock(&connector->eld_mutex);
>>  		ret = drm_eld_size(connector->eld);
>>  		memcpy(buf, connector->eld, min(max_bytes, ret));
>> +		mutex_unlock(&connector->eld_mutex);

All of this is wrapped by the adev->dm.audio_lock mutex. It might
be safer to modify the audio_lock mutex so it only guards the
aconnector->audio_inst access.

But I don't see any way these mutexes would otherwise interact,
so this change should be good as-is.

Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>

Harry

>>  
>>  		break;
>>  	}
>>
>> -- 
>> 2.39.5
>>
>