[PATCHv2,bpf-next,3/5] selftests/bpf: Add re-attach test to fexit_test

Adding the test to re-attach (detach/attach again) tracing
fexit 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@kernel.org>
---
 .../selftests/bpf/prog_tests/fexit_test.c     | 48 +++++++++++++++----
 1 file changed, 38 insertions(+), 10 deletions(-)

On Wed, Apr 7, 2021 at 4:21 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding the test to re-attach (detach/attach again) tracing
> fexit 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@kernel.org>
> ---
>  .../selftests/bpf/prog_tests/fexit_test.c     | 48 +++++++++++++++----
>  1 file changed, 38 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/fexit_test.c b/tools/testing/selftests/bpf/prog_tests/fexit_test.c
> index 78d7a2765c27..579e620e6612 100644
> --- a/tools/testing/selftests/bpf/prog_tests/fexit_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/fexit_test.c
> @@ -3,20 +3,24 @@
>  #include <test_progs.h>
>  #include "fexit_test.skel.h"
>
> -void test_fexit_test(void)
> +static __u32 duration;
> +
> +static int fexit_test(struct fexit_test *fexit_skel)
>  {
> -       struct fexit_test *fexit_skel = NULL;
> +       struct bpf_link *link;
>         int err, prog_fd, i;
> -       __u32 duration = 0, retval;
>         __u64 *result;
> -
> -       fexit_skel = fexit_test__open_and_load();
> -       if (CHECK(!fexit_skel, "fexit_skel_load", "fexit skeleton failed\n"))
> -               goto cleanup;
> +       __u32 retval;
>
>         err = fexit_test__attach(fexit_skel);
>         if (CHECK(err, "fexit_attach", "fexit attach failed: %d\n", err))
> -               goto cleanup;
> +               return err;
> +
> +       /* Check that already linked program can't be attached again. */
> +       link = bpf_program__attach(fexit_skel->progs.test1);
> +       if (CHECK(!IS_ERR(link), "fexit_attach_link",
> +                 "re-attach without detach should not succeed"))
> +               return -1;
>
>         prog_fd = bpf_program__fd(fexit_skel->progs.test1);
>         err = bpf_prog_test_run(prog_fd, 1, NULL, 0,
> @@ -26,12 +30,36 @@ void test_fexit_test(void)
>               err, errno, retval, duration);
>
>         result = (__u64 *)fexit_skel->bss;
> -       for (i = 0; i < 6; i++) {
> +       for (i = 0; i < 8; i++) {
>                 if (CHECK(result[i] != 1, "result",
>                           "fexit_test%d failed err %lld\n", i + 1, result[i]))
> -                       goto cleanup;
> +                       return -1;
>         }
>
> +       fexit_test__detach(fexit_skel);
> +
> +       /* zero results for re-attach test */
> +       for (i = 0; i < 8; i++)
> +               result[i] = 0;

memset(fexit_skel->bss, 0, sizeof(*fexit_skel->bss)) ? ;)

and see my nits in previous patch about ASSERT over CHECK


> +       return 0;
> +}
> +
> +void test_fexit_test(void)
> +{
> +       struct fexit_test *fexit_skel = NULL;
> +       int err;
> +
> +       fexit_skel = fexit_test__open_and_load();
> +       if (CHECK(!fexit_skel, "fexit_skel_load", "fexit skeleton failed\n"))
> +               goto cleanup;
> +
> +       err = fexit_test(fexit_skel);
> +       if (CHECK(err, "fexit_test", "first attach failed\n"))
> +               goto cleanup;
> +
> +       err = fexit_test(fexit_skel);
> +       CHECK(err, "fexit_test", "second attach failed\n");
> +
>  cleanup:
>         fexit_test__destroy(fexit_skel);
>  }
> --
> 2.30.2
>