linux-kernel - Re: [PATCH bpf-next v2] selftests/bpf: fix incorrect fcntl call (test

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Message-ID: <632cad99e05c2_3c2b22088@john.notmuch>
Date:   Thu, 22 Sep 2022 11:46:49 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>,
        John Fastabend <john.fastabend@...il.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Qiao Ma <mqaio@...ux.alibaba.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Shuah Khan <shuah@...nel.org>, Mykola Lysenko <mykolal@...com>,
        LKML <linux-kernel@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH bpf-next v2] selftests/bpf: fix incorrect fcntl call
 (test_sockmap.c)

Andrii Nakryiko wrote:
> On Fri, Aug 26, 2022 at 9:24 AM John Fastabend <john.fastabend@...il.com> wrote:
> >
> > Alexei Starovoitov wrote:
> > > On Wed, Aug 24, 2022 at 7:11 PM Qiao Ma <mqaio@...ux.alibaba.com> 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@...ux.alibaba.com>
> > > > ---
> > > >  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.

.John