Yes, it appears so. I would suggest to come up with a patch which overrides modify() for all those selectors which can benefit from it (poll, epoll, kqueue) and refactor register() / unregister() (for select) in a separate issue / patch. Also, I suppose a couple of tests should be added (if not there already) in order to make sure that 'events' and 'data' arguments get actually changed in different situations.