drm/ttm/nouveau: don't call tt destroy callback on alloc failure.

commit 5de5b6ecf97a021f29403aa272cb4e03318ef586 upstream.

This is confusing, and from my reading of all the drivers only
nouveau got this right.

Just make the API act under driver control of it's own allocation
failing, and don't call destroy, if the page table fails to
create there is nothing to cleanup here.

(I'm willing to believe I've missed something here, so please
review deeply).

Reviewed-by: Christian König <[email protected]>
Signed-off-by: Dave Airlie <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
[bwh: Backported to 4.14:
 - Drop change in ttm_sg_tt_init()
 - Adjust context]
Signed-off-by: Ben Hutchings <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/gpu/drm/nouveau/nouveau_sgdma.c

@@ -105,12 +105,9 @@ nouveau_sgdma_create_ttm(struct ttm_bo_device *bdev,
 	else
 		nvbe->ttm.ttm.func = &nv50_sgdma_backend;
 
-	if (ttm_dma_tt_init(&nvbe->ttm, bdev, size, page_flags, dummy_read_page))
-		/*
-		 * A failing ttm_dma_tt_init() will call ttm_tt_destroy()
-		 * and thus our nouveau_sgdma_destroy() hook, so we don't need
-		 * to free nvbe here.
-		 */
+	if (ttm_dma_tt_init(&nvbe->ttm, bdev, size, page_flags, dummy_read_page)) {
+		kfree(nvbe);
 		return NULL;
+	}
 	return &nvbe->ttm.ttm;
 }

drivers/gpu/drm/ttm/ttm_tt.c

@@ -195,7 +195,6 @@ int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
 
 	ttm_tt_alloc_page_directory(ttm);
 	if (!ttm->pages) {
-		ttm_tt_destroy(ttm);
 		pr_err("Failed allocating page table\n");
 		return -ENOMEM;
 	}
@@ -228,7 +227,6 @@ int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev,
 	INIT_LIST_HEAD(&ttm_dma->pages_list);
 	ttm_dma_tt_alloc_page_directory(ttm_dma);
 	if (!ttm->pages) {
-		ttm_tt_destroy(ttm);
 		pr_err("Failed allocating page table\n");
 		return -ENOMEM;
 	}