drm/qxl: add lock asserts to qxl_bo_vmap_locked + qxl_bo_vunmap_locked

Try avoid re-introducing locking bugs.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20210217123213.2199186-12-kraxel@redhat.com

drivers/gpu/drm/qxl/qxl_object.c

@@ -162,6 +162,8 @@ int qxl_bo_vmap_locked(struct qxl_bo *bo, struct dma_buf_map *map)
 {
 	int r;
 
+	dma_resv_assert_held(bo->tbo.base.resv);
+
 	if (bo->kptr) {
 		bo->map_count++;
 		goto out;
@@ -236,6 +238,8 @@ void *qxl_bo_kmap_atomic_page(struct qxl_device *qdev,
 
 void qxl_bo_vunmap_locked(struct qxl_bo *bo)
 {
+	dma_resv_assert_held(bo->tbo.base.resv);
+
 	if (bo->kptr == NULL)
 		return;
 	bo->map_count--;