netdev - Re: [PATCHv4 bpf-next 2/5] selftests/bpf: Add re-attach test to fentry

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Date:   Wed, 14 Apr 2021 12:56:59 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Jiri Olsa <jolsa@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Julia Lawall <julia.lawall@...ia.fr>
Subject: Re: [PATCHv4 bpf-next 2/5] selftests/bpf: Add re-attach test to
 fentry_test

On Tue, Apr 13, 2021 at 02:54:10PM -0700, Andrii Nakryiko wrote:

SNIP

> >         __u32 duration = 0, retval;
> > +       struct bpf_link *link;
> >         __u64 *result;
> >
> > -       fentry_skel = fentry_test__open_and_load();
> > -       if (CHECK(!fentry_skel, "fentry_skel_load", "fentry skeleton failed\n"))
> > -               goto cleanup;
> > -
> >         err = fentry_test__attach(fentry_skel);
> > -       if (CHECK(err, "fentry_attach", "fentry attach failed: %d\n", err))
> > -               goto cleanup;
> > +       if (!ASSERT_OK(err, "fentry_attach"))
> > +               return err;
> > +
> > +       /* Check that already linked program can't be attached again. */
> > +       link = bpf_program__attach(fentry_skel->progs.test1);
> > +       if (!ASSERT_ERR_PTR(link, "fentry_attach_link"))
> > +               return -1;
> >
> >         prog_fd = bpf_program__fd(fentry_skel->progs.test1);
> >         err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> >                                 NULL, NULL, &retval, &duration);
> > -       CHECK(err || retval, "test_run",
> > -             "err %d errno %d retval %d duration %d\n",
> > -             err, errno, retval, duration);
> > +       ASSERT_OK(err || retval, "test_run");
> 
> this is quite misleading, even if will result in a correct check. Toke
> did this in his patch set:
> 
> ASSERT_OK(err, ...);
> ASSERT_EQ(retval, 0, ...);
> 
> It is a better and more straightforward way to validate the checks
> instead of relying on (err || retval) -> bool (true) -> int (1) -> !=
> 0 chain.

ok, makes sense

SNIP

> > +void test_fentry_test(void)
> > +{
> > +       struct fentry_test *fentry_skel = NULL;
> > +       int err;
> > +
> > +       fentry_skel = fentry_test__open_and_load();
> > +       if (!ASSERT_OK_PTR(fentry_skel, "fentry_skel_load"))
> > +               goto cleanup;
> > +
> > +       err = fentry_test(fentry_skel);
> > +       if (!ASSERT_OK(err, "fentry_first_attach"))
> > +               goto cleanup;
> > +
> > +       err = fentry_test(fentry_skel);
> > +       ASSERT_OK(err, "fentry_second_attach");
> > +
> >  cleanup:
> >         fentry_test__destroy(fentry_skel);
> >  }
> > diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
> > index e87c8546230e..ee7e3b45182a 100644
> > --- a/tools/testing/selftests/bpf/test_progs.h
> > +++ b/tools/testing/selftests/bpf/test_progs.h
> > @@ -210,7 +210,7 @@ extern int test__join_cgroup(const char *path);
> >  #define ASSERT_ERR_PTR(ptr, name) ({                                   \
> >         static int duration = 0;                                        \
> >         const void *___res = (ptr);                                     \
> > -       bool ___ok = IS_ERR(___res)                                     \
> > +       bool ___ok = IS_ERR(___res);                                    \
> 
> heh, it probably deserves a separate patch with Fixes tag...

va bene

jirka