iris: refcount separate screen objects for resource tracking

this screen object can never, ever be accessed like this in a resource,
as it may have previously been replaced by a wrapper (e.g., driver trace)
which will then explode when it is accessed directly

instead, keep a separate screen ref on the resource which is known to be
the actual driver object and not a wrapper

Fixes: 0a497eb130 ("iris: make resources take a ref on the screen object")

Reviewed-by: Lionel Landwerlin lionel.g.landwerlin@intel.com
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10632>
(cherry picked from commit eb63c7dece)

.pick_status.json

@@ -13,7 +13,7 @@
         "description": "iris: refcount separate screen objects for resource tracking",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": "0a497eb1303d23f04ad7d9c28abf953a9105e32a"
     },

src/gallium/drivers/iris/iris_resource.c

@@ -415,7 +415,7 @@ iris_resource_destroy(struct pipe_screen *screen,
 
    threaded_resource_deinit(p_res);
    iris_bo_unreference(res->bo);
-   iris_pscreen_unref(res->base.b.screen);
+   iris_pscreen_unref(res->orig_screen);
 
    free(res);
 }
@@ -429,7 +429,8 @@ iris_alloc_resource(struct pipe_screen *pscreen,
       return NULL;
 
    res->base.b = *templ;
-   res->base.b.screen = iris_pscreen_ref(pscreen);
+   res->base.b.screen = pscreen;
+   res->orig_screen = iris_pscreen_ref(pscreen);
    pipe_reference_init(&res->base.b.reference, 1);
    threaded_resource_init(&res->base.b);
 

src/gallium/drivers/iris/iris_resource.h

@@ -168,6 +168,11 @@ struct iris_resource {
     * be DRM_FORMAT_MOD_INVALID.
     */
    const struct isl_drm_modifier_info *mod_info;
+
+   /**
+    * The screen the resource was originally created with, stored for refcounting.
+    */
+   struct pipe_screen *orig_screen;
 };
 
 /**