[PATCH 1/2] drm/amd/amdgpu: lock reservation object while creating shadow bo

[Christian König]

Am 11.01.2017 um 08:31 schrieb Nicolai Hähnle:
> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> ttm_bo_init checks that the reservation object is locked. This is
> the caller's responsibility when resv != NULL. Otherwise, the inline
> reservation object of the newly allocated buffer is used and must
> explicitly be locked. Using a trylock is fine, since nobody else
> has a reference to the reservation lock.

Good, catch. But while using trylock is fine, why do you need to use it 
in the first place?

Regards,
Christian.

>
> Signed-off-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 11 +++++++++++
>   1 file changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index 11c12c4d..357eed9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -465,21 +465,32 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
>   	amdgpu_ttm_placement_init(adev, &placement,
>   				  placements, domain, flags);
>   
>   	r = amdgpu_bo_create_restricted(adev, size, byte_align, kernel,
>   					domain, flags, sg, &placement,
>   					resv, bo_ptr);
>   	if (r)
>   		return r;
>   
>   	if (amdgpu_need_backup(adev) && (flags & AMDGPU_GEM_CREATE_SHADOW)) {
> +		if (!resv) {
> +			bool locked;
> +
> +			locked = ww_mutex_trylock(&(*bo_ptr)->tbo.resv->lock);
> +			WARN_ON(!locked);
> +		}
> +
>   		r = amdgpu_bo_create_shadow(adev, size, byte_align, (*bo_ptr));
> +
> +		if (!resv)
> +			ww_mutex_unlock(&(*bo_ptr)->tbo.resv->lock);
> +
>   		if (r)
>   			amdgpu_bo_unref(bo_ptr);
>   	}
>   
>   	return r;
>   }
>   
>   int amdgpu_bo_backup_to_shadow(struct amdgpu_device *adev,
>   			       struct amdgpu_ring *ring,
>   			       struct amdgpu_bo *bo,