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

["Christian König" <christian.koenig@amd.com>]

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.

>
> 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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