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

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

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.
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.

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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