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

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

Am 08.12.20 um 19:52 schrieb Andrey Grodzovsky:
>
> 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 ?

Maybe we should move the error handling into amdgpu_gem_create_ioctl() 
anyway.

We don't really want that handling in the userptr stuff and for the call 
from amdgpufb_create_pinned_object() that is actually a bug!

E.g. for the fb emulation we can't fall back from VRAM to GTT like in 
the create ioctl.

Christian.

>
> 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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