netdev - Re: [PATCHv2 bpf-next 2/5] selftests/bpf: Add re-attach test to fentry

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Date:   Wed, 7 Apr 2021 15:47:30 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     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>
Subject: Re: [PATCHv2 bpf-next 2/5] selftests/bpf: Add re-attach test to fentry_test

On Wed, Apr 7, 2021 at 4:21 AM Jiri Olsa <jolsa@...nel.org> wrote:
>
> Adding the test to re-attach (detach/attach again) tracing
> fentry programs, plus check that already linked program can't
> be attached again.
>
> Fixing the number of check-ed results, which should be 8.
>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  .../selftests/bpf/prog_tests/fentry_test.c    | 48 +++++++++++++++----
>  1 file changed, 38 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/fentry_test.c b/tools/testing/selftests/bpf/prog_tests/fentry_test.c
> index 04ebbf1cb390..1f7566e772e9 100644
> --- a/tools/testing/selftests/bpf/prog_tests/fentry_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/fentry_test.c
> @@ -3,20 +3,24 @@
>  #include <test_progs.h>
>  #include "fentry_test.skel.h"
>
> -void test_fentry_test(void)
> +static __u32 duration;
> +
> +static int fentry_test(struct fentry_test *fentry_skel)
>  {
> -       struct fentry_test *fentry_skel = NULL;
> +       struct bpf_link *link;
>         int err, prog_fd, i;
> -       __u32 duration = 0, retval;
>         __u64 *result;
> -
> -       fentry_skel = fentry_test__open_and_load();
> -       if (CHECK(!fentry_skel, "fentry_skel_load", "fentry skeleton failed\n"))
> -               goto cleanup;
> +       __u32 retval;
>
>         err = fentry_test__attach(fentry_skel);
>         if (CHECK(err, "fentry_attach", "fentry attach failed: %d\n", err))
> -               goto cleanup;
> +               return err;
> +
> +       /* Check that already linked program can't be attached again. */
> +       link = bpf_program__attach(fentry_skel->progs.test1);
> +       if (CHECK(!IS_ERR(link), "fentry_attach_link",

if (!ASSERT_ERR_PTR(link, "fentry_attach_link")) ?

> +                 "re-attach without detach should not succeed"))
> +               return -1;
>
>         prog_fd = bpf_program__fd(fentry_skel->progs.test1);
>         err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> @@ -26,12 +30,36 @@ void test_fentry_test(void)
>               err, errno, retval, duration);
>
>         result = (__u64 *)fentry_skel->bss;
> -       for (i = 0; i < 6; i++) {
> +       for (i = 0; i < 8; i++) {

how about using sizeof(*fentry_skel->bss) / sizeof(__u64) ?

>                 if (CHECK(result[i] != 1, "result",
>                           "fentry_test%d failed err %lld\n", i + 1, result[i]))
> -                       goto cleanup;
> +                       return -1;
>         }
>
> +       fentry_test__detach(fentry_skel);
> +
> +       /* zero results for re-attach test */
> +       for (i = 0; i < 8; i++)
> +               result[i] = 0;
> +       return 0;
> +}
> +
> +void test_fentry_test(void)
> +{
> +       struct fentry_test *fentry_skel = NULL;
> +       int err;
> +
> +       fentry_skel = fentry_test__open_and_load();
> +       if (CHECK(!fentry_skel, "fentry_skel_load", "fentry skeleton failed\n"))
> +               goto cleanup;
> +
> +       err = fentry_test(fentry_skel);
> +       if (CHECK(err, "fentry_test", "first attach failed\n"))
> +               goto cleanup;
> +
> +       err = fentry_test(fentry_skel);
> +       CHECK(err, "fentry_test", "second attach failed\n");

overall: please try to use ASSERT_xxx macros, they are easier to
follow and require less typing
> +
>  cleanup:
>         fentry_test__destroy(fentry_skel);
>  }
> --
> 2.30.2
>