netdev - Re: [PATCH bpf-next 02/11] selftest/bpf: relax btf

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Message-ID: <CAPhsuW6DxoRjBPJEgwzEtmVt-Uunw-MAmAF2tgh-ksjcKuJ4Bw@mail.gmail.com>
Date:   Fri, 30 Oct 2020 09:43:35 -0700
From:   Song Liu <song@...nel.org>
To:     Andrii Nakryiko <andrii@...nel.org>
Cc:     bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf-next 02/11] selftest/bpf: relax btf_dedup test checks

On Thu, Oct 29, 2020 at 1:40 AM Andrii Nakryiko <andrii@...nel.org> wrote:
>
> Remove the requirement of a strictly exact string section contents. This used
> to be true when string deduplication was done through sorting, but with string
> dedup done through hash table, it's no longer true. So relax test harness to
> relax strings checks and, consequently, type checks, which now don't have to
> have exactly the same string offsets.
>
> Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
> ---
>  tools/testing/selftests/bpf/prog_tests/btf.c | 34 +++++++++++---------
>  1 file changed, 19 insertions(+), 15 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
> index 93162484c2ca..2ccc23b2a36f 100644
> --- a/tools/testing/selftests/bpf/prog_tests/btf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/btf.c
> @@ -6652,7 +6652,7 @@ static void do_test_dedup(unsigned int test_num)
>         const void *test_btf_data, *expect_btf_data;
>         const char *ret_test_next_str, *ret_expect_next_str;
>         const char *test_strs, *expect_strs;
> -       const char *test_str_cur, *test_str_end;
> +       const char *test_str_cur;
>         const char *expect_str_cur, *expect_str_end;
>         unsigned int raw_btf_size;
>         void *raw_btf;
> @@ -6719,12 +6719,18 @@ static void do_test_dedup(unsigned int test_num)
>                 goto done;
>         }
>
> -       test_str_cur = test_strs;
> -       test_str_end = test_strs + test_hdr->str_len;
>         expect_str_cur = expect_strs;
>         expect_str_end = expect_strs + expect_hdr->str_len;
> -       while (test_str_cur < test_str_end && expect_str_cur < expect_str_end) {
> +       while (expect_str_cur < expect_str_end) {
>                 size_t test_len, expect_len;
> +               int off;
> +
> +               off = btf__find_str(test_btf, expect_str_cur);
> +               if (CHECK(off < 0, "exp str '%s' not found: %d\n", expect_str_cur, off)) {
> +                       err = -1;
> +                       goto done;
> +               }
> +               test_str_cur = btf__str_by_offset(test_btf, off);
>
>                 test_len = strlen(test_str_cur);
>                 expect_len = strlen(expect_str_cur);
> @@ -6741,15 +6747,8 @@ static void do_test_dedup(unsigned int test_num)
>                         err = -1;
>                         goto done;
>                 }
> -               test_str_cur += test_len + 1;
>                 expect_str_cur += expect_len + 1;
>         }
> -       if (CHECK(test_str_cur != test_str_end,
> -                 "test_str_cur:%p != test_str_end:%p",
> -                 test_str_cur, test_str_end)) {
> -               err = -1;
> -               goto done;
> -       }
>
>         test_nr_types = btf__get_nr_types(test_btf);
>         expect_nr_types = btf__get_nr_types(expect_btf);
> @@ -6775,10 +6774,15 @@ static void do_test_dedup(unsigned int test_num)
>                         err = -1;
>                         goto done;
>                 }
> -               if (CHECK(memcmp((void *)test_type,
> -                                (void *)expect_type,
> -                                test_size),
> -                         "type #%d: contents differ", i)) {

I guess test_size and expect_size are not needed anymore?

> +               if (CHECK(btf_kind(test_type) != btf_kind(expect_type),
> +                         "type %d kind: exp %d != got %u\n",
> +                         i, btf_kind(expect_type), btf_kind(test_type))) {
> +                       err = -1;
> +                       goto done;
> +               }
> +               if (CHECK(test_type->info != expect_type->info,
> +                         "type %d info: exp %d != got %u\n",
> +                         i, expect_type->info, test_type->info)) {

btf_kind() returns part of ->info, so we only need the second check, no?

IIUC, test_type and expect_type may have different name_off now. Shall
we check ->size matches?


>                         err = -1;
>                         goto done;
>                 }
> --
> 2.24.1
>