Re: [PATCH net-next v2] selftest: epoll_busy_poll: epoll busy poll tests

From: Joe Damato
Date: Mon May 06 2024 - 21:40:29 EST


On Mon, May 06, 2024 at 06:12:54PM -0700, Jakub Kicinski wrote:
> On Mon, 6 May 2024 20:53:22 +0000 Joe Damato wrote:
> > Add a simple test for the epoll busy poll ioctls, using the kernel
> > selftest harness.
> >
> > This test ensures that the ioctls have the expected return codes and
> > that the kernel properly gets and sets epoll busy poll parameters.
> >
> > The test can be expanded in the future to do real busy polling (provided
> > another machine to act as the client is available).
>
> Hm, we get:
>
> # timeout set to 3600
> # selftests: net: epoll_busy_poll
> # TAP version 13
> # 1..5
> # # Starting 5 tests from 2 test cases.
> # # RUN invalid_fd.test_invalid_fd ...
> # # OK invalid_fd.test_invalid_fd
> # ok 1 invalid_fd.test_invalid_fd
> # # RUN epoll_busy_poll.test_get_params ...
> # # OK epoll_busy_poll.test_get_params
> # ok 2 epoll_busy_poll.test_get_params
> # # RUN epoll_busy_poll.test_set_invalid ...
> # # epoll_busy_poll.c:204:test_set_invalid:Expected -1 (-1) == ret (0)
> # # epoll_busy_poll.c:205:test_set_invalid:EPIOCSPARAMS should error busy_poll_budget > NAPI_POLL_WEIGHT
> # # epoll_busy_poll.c:207:test_set_invalid:Expected EPERM (1) == errno (22)
> # # epoll_busy_poll.c:208:test_set_invalid:EPIOCSPARAMS errno should be EPERM busy_poll_budget > NAPI_POLL_WEIGHT
> # # test_set_invalid: Test failed
> # # FAIL epoll_busy_poll.test_set_invalid
> # not ok 3 epoll_busy_poll.test_set_invalid
> # # RUN epoll_busy_poll.test_set_and_get_valid ...
> # # OK epoll_busy_poll.test_set_and_get_valid
> # ok 4 epoll_busy_poll.test_set_and_get_valid
> # # RUN epoll_busy_poll.test_invalid_ioctl ...
> # # OK epoll_busy_poll.test_invalid_ioctl
> # ok 5 epoll_busy_poll.test_invalid_ioctl
>
> https://netdev-3.bots.linux.dev/vmksft-net/results/584001/98-epoll-busy-poll/stdout

Ah, sorry -- this is because I had assumed the test would run without
CAP_NET_ADMIN, but since:

epoll_busy_poll.c:204:test_set_invalid:Expected -1 (-1) == ret (0)

succeeds (ret = 0), clearly I am mistaken. Sorry about that.

I think I'll spin up a v3 and I'll add a test with and without
CAP_NET_ADMIN to check both cases, which would probably be better anyway.