[PATCH libdrm] amdgpu: add amdgpu_bo_handle_type_kms_noimport

[Michel Dänzer]

On 2018-07-12 07:03 PM, Marek Olšák wrote:
> On Thu, Jul 12, 2018, 3:31 AM Michel Dänzer <michel at daenzer.net> wrote:
>> On 2018-07-12 02:47 AM, Marek Olšák wrote:
>>> From: Marek Olšák <marek.olsak at amd.com>
>>>
>>> diff --git a/amdgpu/amdgpu_bo.c b/amdgpu/amdgpu_bo.c
>>> index 9e37b149..d29be244 100644
>>> --- a/amdgpu/amdgpu_bo.c
>>> +++ b/amdgpu/amdgpu_bo.c
>>> @@ -234,20 +234,22 @@ int amdgpu_bo_export(amdgpu_bo_handle bo,
>>>       case amdgpu_bo_handle_type_gem_flink_name:
>>>               r = amdgpu_bo_export_flink(bo);
>>>               if (r)
>>>                       return r;
>>>
>>>               *shared_handle = bo->flink_name;
>>>               return 0;
>>>
>>>       case amdgpu_bo_handle_type_kms:
>>>               amdgpu_add_handle_to_table(bo);
>>> +             /* fall through */
>>> +     case amdgpu_bo_handle_type_kms_noimport:
>>>               *shared_handle = bo->handle;
>>>               return 0;
>>
>> What is the rationale for this? I.e. why do you want to not store some
>> handles in the hash table?
> 
> 
> Because I have the option.

Seems like you're expecting this patch to be accepted without providing
any real justification for it (here or in the corresponding Mesa patch).
NAK from me if so.


>> And how can code using amdgpu_bo_handle_type_kms_noimport be sure that
>> the BO will never be re-imported via dma-buf?
> 
> That's for the user to decide and prove when it's safe.

We shouldn't even have to think about this, let's use the mental
capacity for more useful things. :)

I'd rather add the handle to the hash table in amdgpu_bo_alloc,
amdgpu_create_bo_from_user_mem and amdgpu_bo_import instead of in
amdgpu_bo_export, making amdgpu_bo_export(bo, amdgpu_bo_handle_type_kms,
...) essentially free. In the unlikely (since allocating a BO from the
kernel is expensive) case that the hash table shows up on profiles, we
can optimize it.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer