Re: [PATCH] drm/amdgpu: Initialise drm_gem_object_funcs for imported BOs

[Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>]

On 12/8/20 1:47 PM, Christian König wrote:
> Am 08.12.20 um 19:44 schrieb Andrey Grodzovsky:
>>
>> On 12/8/20 1:29 PM, Christian König wrote:
>>> Am 08.12.20 um 19:26 schrieb Andrey Grodzovsky:
>>>>
>>>> On 12/8/20 12:36 PM, Christian König wrote:
>>>>> Am 08.12.20 um 18:10 schrieb Andrey Grodzovsky:
>>>>>> For BOs imported from outside of amdgpu, setting of amdgpu_gem_object_funcs
>>>>>> was missing in amdgpu_dma_buf_create_obj. Fix by refactoring BO creation
>>>>>> and amdgpu_gem_object_funcs setting into single function called
>>>>>> from both code paths.
>>>>>
>>>>> Can you outline why we can't use amdgpu_gem_object_create() directly?
>>>>>
>>>>> I mean we have a bit of extra error handling in there and we need to grab 
>>>>> the resv lock and set the domains after creation, but that shouldn't 
>>>>> matter and I don't see why that should not work.
>>>>
>>>>
>>>> On top of what you mentioned you also have bp.domain/bp.preferred_domain 
>>>> being set differently so you need to add another
>>>> argument to amdgpu_gem_object_create to reflect this difference which 
>>>> clutters even more the already cluttered argument list.
>>>
>>> That should be outside of the call to amdgpu_gem_object_create(), similar to 
>>> how it is outside of the amdgpu_bo_create currently.
>>
>>
>> So you agree we have to add another argument to amdgpu_gem_object_create 
>> (e.g. u32 preferred_domain) which will be 0 for amdgpu_dma_buf_create_obj
>> and equal to initial_domain for all the code path currently calling 
>> amdgpu_gem_object_create ?
>
> No, I just don't see the need for that. We need to overwrite the preferred 
> domain after the function call anyway.
>
> DMA-buf imports are created with the initial domain CPU and then get that 
> overwritten to GTT after creation.
>
>>
>>
>>>
>>>> Regarding the extra error handling - you have the 'retry' dance in 
>>>> amdgpu_gem_object_create which jumps back to the middle of amdgpu_bo_param
>>>> initialization but you don't have it in amdgpu_dma_buf_create_obj which 
>>>> also complicates the reuse of amdgpu_gem_object_create as is.
>>>
>>> Regarding the extra error handling, that kicks in only when 
>>> AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED is specified as flags or 
>>> AMDGPU_GEM_DOMAIN_VRAM as initial domain. Neither is the case here.
>>
>>
>> Yes, still, it makes me a bit uncomfortable relying on internal 
>> implementation details of an API function I call to do the thing I expect.
>
> Yeah, ok that is a rather good argument.
>
> Christian.


So should I just keep it as is or you think it's still would be more beneficial 
to unify them the way you propose ?

Andrey


>
>>
>> Andrey
>>
>>
>>>
>>> Christian.
>>>
>>>>
>>>> Andrey
>>>>
>>>>
>>>>>
>>>>> Thanks,
>>>>> Christian.
>>>>>
>>>>>>
>>>>>> This fixes null ptr regression casued by commit
>>>>>> d693def drm: Remove obsolete GEM and PRIME callbacks from struct drm_driver
>>>>>>
>>>>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>>>>>> ---
>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 13 ++++++-------
>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c     | 22 +++++++++++++++++-----
>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h     |  5 +++++
>>>>>>   3 files changed, 28 insertions(+), 12 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c 
>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>>>>>> index e5919ef..da4d0ab 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>>>>>> @@ -405,6 +405,7 @@ struct dma_buf *amdgpu_gem_prime_export(struct 
>>>>>> drm_gem_object *gobj,
>>>>>>       return buf;
>>>>>>   }
>>>>>>   +
>>>>>>   /**
>>>>>>    * amdgpu_dma_buf_create_obj - create BO for DMA-buf import
>>>>>>    *
>>>>>> @@ -424,7 +425,7 @@ amdgpu_dma_buf_create_obj(struct drm_device *dev, 
>>>>>> struct dma_buf *dma_buf)
>>>>>>       struct amdgpu_device *adev = drm_to_adev(dev);
>>>>>>       struct amdgpu_bo *bo;
>>>>>>       struct amdgpu_bo_param bp;
>>>>>> -    int ret;
>>>>>> +    struct drm_gem_object *obj;
>>>>>>         memset(&bp, 0, sizeof(bp));
>>>>>>       bp.size = dma_buf->size;
>>>>>> @@ -434,21 +435,19 @@ amdgpu_dma_buf_create_obj(struct drm_device *dev, 
>>>>>> struct dma_buf *dma_buf)
>>>>>>       bp.type = ttm_bo_type_sg;
>>>>>>       bp.resv = resv;
>>>>>>       dma_resv_lock(resv, NULL);
>>>>>> -    ret = amdgpu_bo_create(adev, &bp, &bo);
>>>>>> -    if (ret)
>>>>>> +    obj = amdgpu_gem_object_create_raw(adev, &bp);
>>>>>> +    if (IS_ERR(obj))
>>>>>>           goto error;
>>>>>>   +    bo = gem_to_amdgpu_bo(obj);
>>>>>>       bo->allowed_domains = AMDGPU_GEM_DOMAIN_GTT;
>>>>>>       bo->preferred_domains = AMDGPU_GEM_DOMAIN_GTT;
>>>>>>       if (dma_buf->ops != &amdgpu_dmabuf_ops)
>>>>>>           bo->prime_shared_count = 1;
>>>>>>   -    dma_resv_unlock(resv);
>>>>>> -    return &bo->tbo.base;
>>>>>> -
>>>>>>   error:
>>>>>>       dma_resv_unlock(resv);
>>>>>> -    return ERR_PTR(ret);
>>>>>> +    return obj;
>>>>>>   }
>>>>>>     /**
>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c 
>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>>>>> index c9f94fb..5f22ce6 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>>>>> @@ -52,13 +52,26 @@ static void amdgpu_gem_object_free(struct 
>>>>>> drm_gem_object *gobj)
>>>>>>       }
>>>>>>   }
>>>>>>   +struct drm_gem_object *amdgpu_gem_object_create_raw(struct 
>>>>>> amdgpu_device *adev,
>>>>>> +                            struct amdgpu_bo_param *bp)
>>>>>> +{
>>>>>> +    struct amdgpu_bo *bo;
>>>>>> +    int r;
>>>>>> +
>>>>>> +    r = amdgpu_bo_create(adev, bp, &bo);
>>>>>> +    if (r)
>>>>>> +        return ERR_PTR(r);
>>>>>> +
>>>>>> +    bo->tbo.base.funcs = &amdgpu_gem_object_funcs;
>>>>>> +    return &bo->tbo.base;
>>>>>> +}
>>>>>> +
>>>>>>   int amdgpu_gem_object_create(struct amdgpu_device *adev, unsigned long 
>>>>>> size,
>>>>>>                    int alignment, u32 initial_domain,
>>>>>>                    u64 flags, enum ttm_bo_type type,
>>>>>>                    struct dma_resv *resv,
>>>>>>                    struct drm_gem_object **obj)
>>>>>>   {
>>>>>> -    struct amdgpu_bo *bo;
>>>>>>       struct amdgpu_bo_param bp;
>>>>>>       int r;
>>>>>>   @@ -73,8 +86,9 @@ int amdgpu_gem_object_create(struct amdgpu_device 
>>>>>> *adev, unsigned long size,
>>>>>>   retry:
>>>>>>       bp.flags = flags;
>>>>>>       bp.domain = initial_domain;
>>>>>> -    r = amdgpu_bo_create(adev, &bp, &bo);
>>>>>> -    if (r) {
>>>>>> +    *obj = amdgpu_gem_object_create_raw(adev, &bp);
>>>>>> +    if (IS_ERR(*obj)) {
>>>>>> +        r = PTR_ERR(*obj);
>>>>>>           if (r != -ERESTARTSYS) {
>>>>>>               if (flags & AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED) {
>>>>>>                   flags &= ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
>>>>>> @@ -90,8 +104,6 @@ int amdgpu_gem_object_create(struct amdgpu_device 
>>>>>> *adev, unsigned long size,
>>>>>>           }
>>>>>>           return r;
>>>>>>       }
>>>>>> -    *obj = &bo->tbo.base;
>>>>>> -    (*obj)->funcs = &amdgpu_gem_object_funcs;
>>>>>>         return 0;
>>>>>>   }
>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h 
>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
>>>>>> index 637bf51..a6b90d3 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
>>>>>> @@ -38,12 +38,17 @@ unsigned long amdgpu_gem_timeout(uint64_t timeout_ns);
>>>>>>   /*
>>>>>>    * GEM objects.
>>>>>>    */
>>>>>> +
>>>>>> +struct amdgpu_bo_param;
>>>>>> +
>>>>>>   void amdgpu_gem_force_release(struct amdgpu_device *adev);
>>>>>>   int amdgpu_gem_object_create(struct amdgpu_device *adev, unsigned long 
>>>>>> size,
>>>>>>                    int alignment, u32 initial_domain,
>>>>>>                    u64 flags, enum ttm_bo_type type,
>>>>>>                    struct dma_resv *resv,
>>>>>>                    struct drm_gem_object **obj);
>>>>>> +struct drm_gem_object *amdgpu_gem_object_create_raw(struct amdgpu_device 
>>>>>> *adev,
>>>>>> +                            struct amdgpu_bo_param *bp);
>>>>>>     int amdgpu_mode_dumb_create(struct drm_file *file_priv,
>>>>>>                   struct drm_device *dev,
>>>>>
>>>
>
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