Thread safety for epoll/libaio

Li, Peng
2006-02-28T20:36:14Z

I apologize if I should not post this on LKML, but there seems to be
some lack of documentation for using epoll/AIO with threads. Are
these interfaces thread-safe? Can I use them safely in the following
way:

Thread A: while(1) { io_getevents(); ... }
// wait forever until an event occurs, then handles the event and loop

Thread B: while(1) { epoll_wait(); ... }
// same as thread A

Thread C: ... io_submit(); ...

Thread D: ... epoll_ctl(); ....

Suppose thread B calls epoll_wait and blocks before thread D calls
epoll_ctl. Is it safe to do so? Will thread B be notified for the
event submitted by thread D? Thread A and C pose the same question
for AIO.

I wrote a simple program to test these interfaces and they seem to
work without problems, but I am not sure if it is really safe to do so
in general. If all of them works, it seems easy to use epoll and AIO
together as I can simply use another thread to harvest events from
thread A and B and make it look like a unified event notification
interface.

Peng