Re: epoll_wait misses edge-triggered eventfd events: bug in Linux 5.3 and 5.4

[Roman Penyaev]

On 2020-02-03 22:03, Max NeunhÃffer wrote:
> Hi Roman,
>
> Thanks for your quick response. This sounds fantastic!
>
> The epollbug.c program was originally written by my colleague Lars
> Maier and then modified by me and subsequently by Chris Kohlhoff. Note
> that the bugzilla bug report contains altogether three variants which
> test epoll_wait/epoll_ctl in three different ways. It might be
> sensible to take all three variants for the test suite.

I checked 3 variants, they do same things: epoll_ctl() races against
epoll_wait(), and this is exactly the bug reproduction, regardless
actual read() from a file descriptor or EPOLLET flag set.

> I cannot imagine that any of the three authors would object to this, I
> definitely do not, the other two are on Cc in this email and can speak
> for themselves.

I adapted the logic from epollbug.c and included it into 
epoll_wakeup_test.c
test suite, you should have received the email: "[PATCH 3/3] kselftest:
introduce new epoll test case".  Please, take a look or ask your 
colleague
to take a look. If no objections - then fine, leave as is.

Thanks.

--
Roman