EPOLL_CTL_DISABLE and multithreaded applications

I mean "fully processed" by the kernel, which is really the only issue; the application can (and indeed: must, even with the proposed EPOLL_CTL_DISABLE change) control its own concurrency issues with its own locks.

The issue is that the kernel and app are running asynchronously with an implicit race condition around removing file descriptors from epoll; sending a notification through the normal epoll mechanism that the kernel is done should be enough to allow both sides of the API to run asynchronously.