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

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

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 ?


>
>> 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.

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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