Re: [PATCH bpf-next v2] selftests/bpf: fix incorrect fcntl call (test_sockmap.c)

[Daniel Borkmann]

On 9/22/22 8:46 PM, John Fastabend wrote:
> Andrii Nakryiko wrote:
> > On Fri, Aug 26, 2022 at 9:24 AM John Fastabend <john.fastabend@xxxxxxxxx> wrote:
> > > Alexei Starovoitov wrote:
> > > > On Wed, Aug 24, 2022 at 7:11 PM Qiao Ma <mqaio@xxxxxxxxxxxxxxxxx> wrote:
> > > > > In test_sockmap.c, the testcase sets socket nonblock first, and then
> > > > > calls select() and recvmsg() to receive data.
> > > > > If some error occur, nonblock setting will make recvmsg() return
> > > > > immediately, rather than blocking forever.
> > > > >
> > > > > However, the way to call fcntl() to set nonblock is wrong.
> > > > > To set socket noblock, we need to use
> > > > > > fcntl(fd, F_SETFL, O_NONBLOCK);
> > > > > rather than:
> > > > > > fcntl(fd, O_NONBLOCK);
> > > > >
> > > > > Signed-off-by: Qiao Ma <mqaio@xxxxxxxxxxxxxxxxx>
> > > > > ---
> > > > >   tools/testing/selftests/bpf/test_sockmap.c | 7 ++++++-
> > > > >   1 file changed, 6 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/tools/testing/selftests/bpf/test_sockmap.c b/tools/testing/selftests/bpf/test_sockmap.c
> > > > > index 0fbaccdc8861..abb4102f33b0 100644
> > > > > --- a/tools/testing/selftests/bpf/test_sockmap.c
> > > > > +++ b/tools/testing/selftests/bpf/test_sockmap.c
> > > > > @@ -598,7 +598,12 @@ static int msg_loop(int fd, int iov_count, int iov_length, int cnt,
> > > > >                  struct timeval timeout;
> > > > >                  fd_set w;
> > > > >
> > > > > -               fcntl(fd, fd_flags);
> > > > > +               err = fcntl(fd, F_SETFL, fd_flags);
> > > > > +               if (err < 0) {
> > > > > +                       perror("fcntl failed");
> > > > > +                       goto out_errno;
> > > > > +               }
> > > > > +
> > > >
> > > > John, Jakub,
> > > >
> > > > Please review this.
> > > > Unfortunately test_sockmap (and sockmap kernel) is broken
> > > > before and after this patch,
> > > > so I'm hesitant to apply it not to make thing harder to debug.
> > > > Here is what I see:
> > > > # ./test_sockmap
>
> [...]
>
> > > > and test_sockmap 'hangs' (or doing something for long time) after
> > > > #31/ 6 sockhash:ktls:txmsg test drop:OK
> > >
> > > Thanks for spotting I'll take a look.
> >
> > Friendly ping. John, did you get a chance to look at this? This patch
> > is still marked as "Needs ACK" in Patchworks.
>
> Yep thanks. We are tracking a couple fixes internally around this so should
> have something pop out soon. I think we want the fix and test to go in at
> the same time.

Ok, I'll mark it as 'awaiting upstream' assuming that you carry this fix forward
together with your series then.

Thanks,
Daniel