Created attachment 288761 [details]
Test program to compare poll() to io_uring ADD_POLL

io_uring POLL_ADD should return identical results to poll/epoll.
(With the possible exception of epoll not accepting regular files.)

Test program performs 3 steps using fd = 0.

0. poll() for POLLIN
1. epoll() for POLLIN
2. io_uring poll for POLLIN

The expected result is that each step returns identical information.

The actual result is:

A) As expected, if fd 0 is a pipe.

B) But if fd 0 is a tty:

a
do_poll: events 00000001
  read 2 bytes: a
b
do_epoll: events 00000001
  read 2 bytes: b
do_io_uring_poll() failed, errno 22: Invalid argument


Test program attached.