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

[Christian König <christian.koenig@xxxxxxx>]

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@xxxxxxx>
> > > > > ---
> > > > >   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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