Sashiko suggests to check the results of pipe() and write() as well:
https://sashiko.dev/#/patchset/amna1QtCtqll1LFj%40redhat.com
Not sure this makes sense, but I'll send V2 just in case.
Oleg.
On 07/29, Oleg Nesterov wrote:
>
> pipe->poll_usage was added to ensure that edge-triggered epoll consumers
> get a wakeup on every write, even if the pipe was already non-empty.
> However, none of the existing epoll_wakeup_test cases cover this; the
> test suite passes even with WRITE_ONCE(pipe->poll_usage, true) removed.
>
> Add a test that writes twice to a pipe and verifies that epoll_wait with
> EPOLLET reports data each time. This covers the pipe-specific per-write
> wakeup behavior that edge-triggered consumers depend on.
>
> Signed-off-by: Oleg Nesterov <[email protected]>
> ---
> .../filesystems/epoll/epoll_wakeup_test.c | 24 +++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
> b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
> index f6f1a7ff01b0..6ad7905ef95a 100644
> --- a/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
> +++ b/tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
> @@ -3538,4 +3538,28 @@ TEST(epoll65)
> close(ctx.efd[1]);
> }
>
> +TEST(epoll66)
> +{
> + struct epoll_event event;
> + int pfd[2], efd, err;
> +
> + pipe(pfd);
> +
> + efd = epoll_create1(0);
> + ASSERT_GE(efd, 0);
> +
> + event.events = EPOLLIN | EPOLLET;
> + err = epoll_ctl(efd, EPOLL_CTL_ADD, pfd[0], &event);
> + ASSERT_EQ(err, 0);
> +
> + for (int i = 0; i < 2; ++i) {
> + write(pfd[1], "", 1);
> + EXPECT_EQ(epoll_wait(efd, &event, 1, 0), 1);
> + }
> +
> + close(pfd[0]);
> + close(pfd[1]);
> + close(efd);
> +}
> +
> TEST_HARNESS_MAIN
> --
> 2.52.0
>
