etnaviv: drm: assert mutual exclusivity between cache and zombie list

The BO list member is used to track the BO both on the cache bucket list
as well as the zombie list. The BO being on both lists at the same time
is an invalid state. Add some asserts to validate this assumption.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <cgmeiner@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32233>

src/etnaviv/drm/etnaviv_bo.c

@@ -118,6 +118,7 @@ void etna_bo_free(struct etna_bo *bo) {
 	if (dev->use_softpin) {
 		etna_bo_cleanup_zombies(dev);
 		VG_BO_RELEASE(bo);
+		assert(!list_is_linked(&bo->list));
 		list_addtail(&bo->list, &dev->zombie_list);
 	} else {
 		_etna_bo_free(bo);

src/etnaviv/drm/etnaviv_bo_cache.c

@@ -185,6 +185,7 @@ int etna_bo_cache_free(struct etna_bo_cache *cache, struct etna_bo *bo)
 
 		bo->free_time = time.tv_sec;
 		VG_BO_RELEASE(bo);
+		assert(!list_is_linked(&bo->list));
 		list_addtail(&bo->list, &bucket->list);
 		etna_bo_cache_cleanup(cache, time.tv_sec);