[PATCH -next 12/18] drm/ttm: Export ttm_bo_reference_unless_doomed()

[Christian König]

Am 26.09.2018 um 18:18 schrieb Thomas Hellstrom:
> Export ttm_bo_reference_unless_doomed() to be used when looking up buffer
> objects that are removed from the lookup structure in the destructor.
>
> Cc: Christian König <christian.koenig at amd.com>
> Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
> Reviewed-by: Sinclair Yeh <syeh at vmware.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo_vm.c |  3 +--
>   include/drm/ttm/ttm_bo_api.h    | 18 ++++++++++++++++++
>   2 files changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 6fe91c1b692d..ec4b09366213 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -409,8 +409,7 @@ static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,
>   	node = drm_vma_offset_lookup_locked(&bdev->vma_manager, offset, pages);
>   	if (likely(node)) {
>   		bo = container_of(node, struct ttm_buffer_object, vma_node);
> -		if (!kref_get_unless_zero(&bo->kref))
> -			bo = NULL;
> +		bo = ttm_bo_reference_unless_doomed(bo);
>   	}
>   
>   	drm_vma_offset_unlock_lookup(&bdev->vma_manager);
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 8c19470785e2..b6bf6b086576 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -312,6 +312,24 @@ ttm_bo_reference(struct ttm_buffer_object *bo)
>   	return bo;
>   }
>   
> +/**
> + * ttm_bo_reference_unless_doomed - reference a struct ttm_buffer_object unless
> + * its refcount has already reached zero.
> + * @bo: The buffer object.
> + *
> + * Used to reference a TTM buffer object in lookups where the object is removed
> + * from the lookup structure during the destructor and for RCU lookups.
> + *
> + * Returns: @bo if the referencing was successful, NULL otherwise.
> + */
> +static inline __must_check struct ttm_buffer_object *
> +ttm_bo_reference_unless_doomed(struct ttm_buffer_object *bo)

Please name that ttm_bo_get_rcu(), we are in the process of renaming 
ttm_bo_reference into ttm_bo_get as well.

Christian.

> +{
> +	if (!kref_get_unless_zero(&bo->kref))
> +		return NULL;
> +	return bo;
> +}
> +
>   /**
>    * ttm_bo_wait - wait for buffer idle.
>    *