next_service_by_instance
while ((service = next_service_by_instance(state, instance, &i)) != NULL) {
while ((service = next_service_by_instance(state, instance, &i)) != NULL) {
while ((service = next_service_by_instance(state, instance, &i))) {
while ((service = next_service_by_instance(state, instance, &i))) {
while ((service = next_service_by_instance(instance->state,
next_service_by_instance(struct vchiq_state *state,