drm/nouveau: embed gem object in nouveau_bo

There is no reason to keep the gem object separately allocated. nouveau is
the last user of gem_obj->driver_private, so if we embed it, we can get
rid of 8bytes per gem-object.

The implementation follows the radeon driver. bo->gem is only valid, iff
the bo was created via the gem helpers _and_ iff the user holds a valid
gem reference. That is, as the gem object holds a reference to the
nouveau_bo. If you use nouveau_ref() to gain a bo reference, you are not
guaranteed to also hold a gem reference. The gem object might get
destroyed after the last user drops the gem-ref via
drm_gem_object_unreference(). Use drm_gem_object_reference() to gain a
gem-reference.

For debugging, we can use bo->gem.filp != NULL to test whether a gem-bo is
valid. However, this shouldn't be used for real functionality to avoid
gem-internal dependencies.

Note that the implementation follows the previous style. However, we no
longer can check for bo->gem != NULL to test for a valid gem object. This
wasn't done before, so we should be safe now.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/nouveau/nouveau_abi16.c

@@ -130,7 +130,7 @@ nouveau_abi16_chan_fini(struct nouveau_abi16 *abi16,
 	if (chan->ntfy) {
 		nouveau_bo_vma_del(chan->ntfy, &chan->ntfy_vma);
 		nouveau_bo_unpin(chan->ntfy);
-		drm_gem_object_unreference_unlocked(chan->ntfy->gem);
+		drm_gem_object_unreference_unlocked(&chan->ntfy->gem);
 	}
 
 	if (chan->heap.block_size)
@@ -320,7 +320,7 @@ nouveau_abi16_ioctl_channel_alloc(ABI16_IOCTL_ARGS)
 			goto done;
 	}
 
-	ret = drm_gem_handle_create(file_priv, chan->ntfy->gem,
+	ret = drm_gem_handle_create(file_priv, &chan->ntfy->gem,
 				    &init->notifier_handle);
 	if (ret)
 		goto done;

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -146,7 +146,7 @@ nouveau_bo_del_ttm(struct ttm_buffer_object *bo)
 	struct drm_device *dev = drm->dev;
 	struct nouveau_bo *nvbo = nouveau_bo(bo);
 
-	if (unlikely(nvbo->gem))
+	if (unlikely(nvbo->gem.filp))
 		DRM_ERROR("bo %p still attached to GEM object\n", bo);
 	WARN_ON(nvbo->pin_refcnt > 0);
 	nv10_bo_put_tile_region(dev, nvbo->tile, NULL);
@@ -1267,7 +1267,7 @@ nouveau_bo_verify_access(struct ttm_buffer_object *bo, struct file *filp)
 {
 	struct nouveau_bo *nvbo = nouveau_bo(bo);
 
-	return drm_vma_node_verify_access(&nvbo->gem->vma_node, filp);
+	return drm_vma_node_verify_access(&nvbo->gem.vma_node, filp);
 }
 
 static int

drivers/gpu/drm/nouveau/nouveau_bo.h

@@ -27,7 +27,10 @@ struct nouveau_bo {
 	u32 tile_flags;
 	struct nouveau_drm_tile *tile;
 
-	struct drm_gem_object *gem;
+	/* Only valid if allocated via nouveau_gem_new() and iff you hold a
+	 * gem reference to it! For debugging, use gem.filp != NULL to test
+	 * whether it is valid. */
+	struct drm_gem_object gem;
 
 	/* protect by the ttm reservation lock */
 	int pin_refcnt;

drivers/gpu/drm/nouveau/nouveau_display.c

@@ -50,7 +50,7 @@ nouveau_user_framebuffer_destroy(struct drm_framebuffer *drm_fb)
 	struct nouveau_framebuffer *fb = nouveau_framebuffer(drm_fb);
 
 	if (fb->nvbo)
-		drm_gem_object_unreference_unlocked(fb->nvbo->gem);
+		drm_gem_object_unreference_unlocked(&fb->nvbo->gem);
 
 	drm_framebuffer_cleanup(drm_fb);
 	kfree(fb);
@@ -63,7 +63,7 @@ nouveau_user_framebuffer_create_handle(struct drm_framebuffer *drm_fb,
 {
 	struct nouveau_framebuffer *fb = nouveau_framebuffer(drm_fb);
 
-	return drm_gem_handle_create(file_priv, fb->nvbo->gem, handle);
+	return drm_gem_handle_create(file_priv, &fb->nvbo->gem, handle);
 }
 
 static const struct drm_framebuffer_funcs nouveau_framebuffer_funcs = {
@@ -674,8 +674,8 @@ nouveau_display_dumb_create(struct drm_file *file_priv, struct drm_device *dev,
 	if (ret)
 		return ret;
 
-	ret = drm_gem_handle_create(file_priv, bo->gem, &args->handle);
-	drm_gem_object_unreference_unlocked(bo->gem);
+	ret = drm_gem_handle_create(file_priv, &bo->gem, &args->handle);
+	drm_gem_object_unreference_unlocked(&bo->gem);
 	return ret;
 }
 
@@ -688,7 +688,7 @@ nouveau_display_dumb_map_offset(struct drm_file *file_priv,
 
 	gem = drm_gem_object_lookup(dev, file_priv, handle);
 	if (gem) {
-		struct nouveau_bo *bo = gem->driver_private;
+		struct nouveau_bo *bo = nouveau_gem_object(gem);
 		*poffset = drm_vma_node_offset_addr(&bo->bo.vma_node);
 		drm_gem_object_unreference_unlocked(gem);
 		return 0;

drivers/gpu/drm/nouveau/nouveau_fbcon.c

@@ -420,7 +420,7 @@ nouveau_fbcon_destroy(struct drm_device *dev, struct nouveau_fbdev *fbcon)
 		nouveau_bo_unmap(nouveau_fb->nvbo);
 		nouveau_bo_vma_del(nouveau_fb->nvbo, &nouveau_fb->vma);
 		nouveau_bo_unpin(nouveau_fb->nvbo);
-		drm_gem_object_unreference_unlocked(nouveau_fb->nvbo->gem);
+		drm_gem_object_unreference_unlocked(&nouveau_fb->nvbo->gem);
 		nouveau_fb->nvbo = NULL;
 	}
 	drm_fb_helper_fini(&fbcon->helper);

drivers/gpu/drm/nouveau/nouveau_gem.c

@@ -43,20 +43,17 @@ nouveau_gem_object_new(struct drm_gem_object *gem)
 void
 nouveau_gem_object_del(struct drm_gem_object *gem)
 {
-	struct nouveau_bo *nvbo = gem->driver_private;
+	struct nouveau_bo *nvbo = nouveau_gem_object(gem);
 	struct ttm_buffer_object *bo = &nvbo->bo;
 
-	if (!nvbo)
-		return;
-	nvbo->gem = NULL;
-
 	if (gem->import_attach)
 		drm_prime_gem_destroy(gem, nvbo->bo.sg);
 
-	ttm_bo_unref(&bo);
-
 	drm_gem_object_release(gem);
-	kfree(gem);
+
+	/* reset filp so nouveau_bo_del_ttm() can test for it */
+	gem->filp = NULL;
+	ttm_bo_unref(&bo);
 }
 
 int
@@ -186,14 +183,15 @@ nouveau_gem_new(struct drm_device *dev, int size, int align, uint32_t domain,
 	if (nv_device(drm->device)->card_type >= NV_50)
 		nvbo->valid_domains &= domain;
 
-	nvbo->gem = drm_gem_object_alloc(dev, nvbo->bo.mem.size);
-	if (!nvbo->gem) {
+	/* Initialize the embedded gem-object. We return a single gem-reference
+	 * to the caller, instead of a normal nouveau_bo ttm reference. */
+	ret = drm_gem_object_init(dev, &nvbo->gem, nvbo->bo.mem.size);
+	if (ret) {
 		nouveau_bo_ref(NULL, pnvbo);
 		return -ENOMEM;
 	}
 
-	nvbo->bo.persistent_swap_storage = nvbo->gem->filp;
-	nvbo->gem->driver_private = nvbo;
+	nvbo->bo.persistent_swap_storage = nvbo->gem.filp;
 	return 0;
 }
 
@@ -250,15 +248,15 @@ nouveau_gem_ioctl_new(struct drm_device *dev, void *data,
 	if (ret)
 		return ret;
 
-	ret = drm_gem_handle_create(file_priv, nvbo->gem, &req->info.handle);
+	ret = drm_gem_handle_create(file_priv, &nvbo->gem, &req->info.handle);
 	if (ret == 0) {
-		ret = nouveau_gem_info(file_priv, nvbo->gem, &req->info);
+		ret = nouveau_gem_info(file_priv, &nvbo->gem, &req->info);
 		if (ret)
 			drm_gem_handle_delete(file_priv, req->info.handle);
 	}
 
 	/* drop reference from allocate - handle holds it now */
-	drm_gem_object_unreference_unlocked(nvbo->gem);
+	drm_gem_object_unreference_unlocked(&nvbo->gem);
 	return ret;
 }
 
@@ -266,7 +264,7 @@ static int
 nouveau_gem_set_domain(struct drm_gem_object *gem, uint32_t read_domains,
 		       uint32_t write_domains, uint32_t valid_domains)
 {
-	struct nouveau_bo *nvbo = gem->driver_private;
+	struct nouveau_bo *nvbo = nouveau_gem_object(gem);
 	struct ttm_buffer_object *bo = &nvbo->bo;
 	uint32_t domains = valid_domains & nvbo->valid_domains &
 		(write_domains ? write_domains : read_domains);
@@ -327,7 +325,7 @@ validate_fini_list(struct list_head *list, struct nouveau_fence *fence,
 		list_del(&nvbo->entry);
 		nvbo->reserved_by = NULL;
 		ttm_bo_unreserve_ticket(&nvbo->bo, ticket);
-		drm_gem_object_unreference_unlocked(nvbo->gem);
+		drm_gem_object_unreference_unlocked(&nvbo->gem);
 	}
 }
 
@@ -376,7 +374,7 @@ validate_init(struct nouveau_channel *chan, struct drm_file *file_priv,
 			validate_fini(op, NULL);
 			return -ENOENT;
 		}
-		nvbo = gem->driver_private;
+		nvbo = nouveau_gem_object(gem);
 		if (nvbo == res_bo) {
 			res_bo = NULL;
 			drm_gem_object_unreference_unlocked(gem);
@@ -478,7 +476,7 @@ validate_list(struct nouveau_channel *chan, struct nouveau_cli *cli,
 			return ret;
 		}
 
-		ret = nouveau_gem_set_domain(nvbo->gem, b->read_domains,
+		ret = nouveau_gem_set_domain(&nvbo->gem, b->read_domains,
 					     b->write_domains,
 					     b->valid_domains);
 		if (unlikely(ret)) {

drivers/gpu/drm/nouveau/nouveau_gem.h

@@ -12,7 +12,7 @@
 static inline struct nouveau_bo *
 nouveau_gem_object(struct drm_gem_object *gem)
 {
-	return gem ? gem->driver_private : NULL;
+	return gem ? container_of(gem, struct nouveau_bo, gem) : NULL;
 }
 
 /* nouveau_gem.c */

drivers/gpu/drm/nouveau/nouveau_prime.c

@@ -71,14 +71,16 @@ struct drm_gem_object *nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 		return ERR_PTR(ret);
 
 	nvbo->valid_domains = NOUVEAU_GEM_DOMAIN_GART;
-	nvbo->gem = drm_gem_object_alloc(dev, nvbo->bo.mem.size);
-	if (!nvbo->gem) {
+
+	/* Initialize the embedded gem-object. We return a single gem-reference
+	 * to the caller, instead of a normal nouveau_bo ttm reference. */
+	ret = drm_gem_object_init(dev, &nvbo->gem, nvbo->bo.mem.size);
+	if (ret) {
 		nouveau_bo_ref(NULL, &nvbo);
 		return ERR_PTR(-ENOMEM);
 	}
 
-	nvbo->gem->driver_private = nvbo;
-	return nvbo->gem;
+	return &nvbo->gem;
 }
 
 int nouveau_gem_prime_pin(struct drm_gem_object *obj)