fix the zero-length T_NEXUS

src/vdp_pesi.c

@@ -919,10 +919,27 @@ ved_task(struct worker *wrk, void *priv)
 		Lck_Unlock(&pesi_tree->tree->tree_lock);
 		break;
 	case T_NEXUS:
-		// moved to set_delivered
-		// req_fini(req, wrk);
-		pesi = NULL;
-		task_fini(pesi_tree, req->transport_priv);
+		assert(node->req == req);
+		/*
+		 * XXX rethink: T_NEXUS' req gets fini't in
+		 * bytes_push_worklist(), but not if it had no nodes below,
+		 * because then there were no nodes unpended. so handle the
+		 * "zero object" case here
+		 */
+		if (VSTAILQ_EMPTY(&node->nexus.children)) {
+			assert(node->state == ST_DELIVERED);
+			assert(pesi == req->transport_priv);
+			assert(req == node->req);
+
+			req->transport_priv = NULL;
+			req = NULL;
+			pesi_destroy(&pesi);
+			req_fini(&node->req, wrk);
+			task_fini(pesi_tree, pesi);
+		} else {
+			pesi = NULL;
+			task_fini(pesi_tree, req->transport_priv);
+		}
 		break;
 	default:
 		INCOMPL();