Re: [PATCH 1/3] drm/i915: audit bo->resource usage

[Christian König <christian.koenig@xxxxxxx>]

Hi guys,

can we get an rb/acked-by for this i915 change?

Basically we are just making sure that the driver doesn't crash when 
bo->resource is NULL and a bo doesn't have any backing store assigned to it.

The Intel CI seems to be happy with this change, so I'm pretty sure it 
is correct.

Thanks,
Christian.

Am 24.08.22 um 16:23 schrieb Luben Tuikov:
> From: Christian König <christian.koenig@xxxxxxx>
>
> Make sure we can at least move and alloc TT objects without backing store.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c      | 6 ++----
>   drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c | 2 +-
>   2 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index bc9c432edffe03..45ce2d1f754cc4 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -271,8 +271,6 @@ static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
>   {
>   	struct drm_i915_private *i915 = container_of(bo->bdev, typeof(*i915),
>   						     bdev);
> -	struct ttm_resource_manager *man =
> -		ttm_manager_type(bo->bdev, bo->resource->mem_type);
>   	struct drm_i915_gem_object *obj = i915_ttm_to_gem(bo);
>   	unsigned long ccs_pages = 0;
>   	enum ttm_caching caching;
> @@ -286,8 +284,8 @@ static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
>   	if (!i915_tt)
>   		return NULL;
>   
> -	if (obj->flags & I915_BO_ALLOC_CPU_CLEAR &&
> -	    man->use_tt)
> +	if (obj->flags & I915_BO_ALLOC_CPU_CLEAR && bo->resource &&
> +	    ttm_manager_type(bo->bdev, bo->resource->mem_type)->use_tt)
>   		page_flags |= TTM_TT_FLAG_ZERO_ALLOC;
>   
>   	caching = i915_ttm_select_tt_caching(obj);
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> index 9a7e50534b84bb..c420d1ab605b6f 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> @@ -560,7 +560,7 @@ int i915_ttm_move(struct ttm_buffer_object *bo, bool evict,
>   	bool clear;
>   	int ret;
>   
> -	if (GEM_WARN_ON(!obj)) {
> +	if (GEM_WARN_ON(!obj) || !bo->resource) {
>   		ttm_bo_move_null(bo, dst_mem);
>   		return 0;
>   	}