netdev - Re: [PATCH v2 3/3] tools: add selftest for BPF_F_ZERO

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Message-ID: <CAPhsuW6faksAFzbQsZ6L2fM2VoG6zqSPTmEB+GnUBBGD-YM=Fg@mail.gmail.com>
Date:   Mon, 8 Oct 2018 16:15:30 -0700
From:   Song Liu <liu.song.a23@...il.com>
To:     lmb@...udflare.com
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Networking <netdev@...r.kernel.org>, linux-api@...r.kernel.org
Subject: Re: [PATCH v2 3/3] tools: add selftest for BPF_F_ZERO_SEED

On Mon, Oct 8, 2018 at 3:34 AM Lorenz Bauer <lmb@...udflare.com> wrote:
>
> Check that iterating two separate hash maps produces the same
> order of keys if BPF_F_ZERO_SEED is used.
>
> Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
> ---
>  tools/testing/selftests/bpf/test_maps.c | 68 +++++++++++++++++++++----
>  1 file changed, 57 insertions(+), 11 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
> index 9b552c0fc47d..a8d6af27803a 100644
> --- a/tools/testing/selftests/bpf/test_maps.c
> +++ b/tools/testing/selftests/bpf/test_maps.c
> @@ -257,23 +257,35 @@ static void test_hashmap_percpu(int task, void *data)
>         close(fd);
>  }
>
> +static int helper_fill_hashmap(int max_entries)

How about we add map_flags as the second argument of this function?
This will help
avoid the old_flags hack.

Thanks,
Song

> +{
> +       int i, fd, ret;
> +       long long key, value;
> +
> +       fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value),
> +                           max_entries, map_flags);
> +       CHECK(fd < 0,
> +             "failed to create hashmap",
> +             "err: %s, flags: 0x%x\n", strerror(errno), map_flags);
> +
> +       for (i = 0; i < max_entries; i++) {
> +               key = i; value = key;
> +               ret = bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST);
> +               CHECK(ret != 0,
> +                     "can't update hashmap",
> +                     "err: %s\n", strerror(ret));
> +       }
> +
> +       return fd;
> +}
> +
>  static void test_hashmap_walk(int task, void *data)
>  {
>         int fd, i, max_entries = 1000;
>         long long key, value, next_key;
>         bool next_key_valid = true;
>
> -       fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value),
> -                           max_entries, map_flags);
> -       if (fd < 0) {
> -               printf("Failed to create hashmap '%s'!\n", strerror(errno));
> -               exit(1);
> -       }
> -
> -       for (i = 0; i < max_entries; i++) {
> -               key = i; value = key;
> -               assert(bpf_map_update_elem(fd, &key, &value, BPF_NOEXIST) == 0);
> -       }
> +       fd = helper_fill_hashmap(max_entries);
>
>         for (i = 0; bpf_map_get_next_key(fd, !i ? NULL : &key,
>                                          &next_key) == 0; i++) {
> @@ -305,6 +317,39 @@ static void test_hashmap_walk(int task, void *data)
>         close(fd);
>  }
>
> +static void test_hashmap_zero_seed(void)
> +{
> +       int i, first, second, old_flags;
> +       long long key, next_first, next_second;
> +
> +       old_flags = map_flags;
> +       map_flags |= BPF_F_ZERO_SEED;
> +
> +       first = helper_fill_hashmap(3);
> +       second = helper_fill_hashmap(3);
> +
> +       for (i = 0; ; i++) {
> +               void *key_ptr = !i ? NULL : &key;
> +
> +               if (bpf_map_get_next_key(first, key_ptr, &next_first) != 0)
> +                       break;
> +
> +               CHECK(bpf_map_get_next_key(second, key_ptr, &next_second) != 0,
> +                     "next_key for second map must succeed",
> +                     "key_ptr: %p", key_ptr);
> +               CHECK(next_first != next_second,
> +                     "keys must match",
> +                     "i: %d first: %lld second: %lld\n", i,
> +                     next_first, next_second);
> +
> +               key = next_first;
> +       }
> +
> +       map_flags = old_flags;
> +       close(first);
> +       close(second);
> +}
> +
>  static void test_arraymap(int task, void *data)
>  {
>         int key, next_key, fd;
> @@ -1417,6 +1462,7 @@ static void run_all_tests(void)
>         test_hashmap(0, NULL);
>         test_hashmap_percpu(0, NULL);
>         test_hashmap_walk(0, NULL);
> +       test_hashmap_zero_seed();
>
>         test_arraymap(0, NULL);
>         test_arraymap_percpu(0, NULL);
> --
> 2.17.1
>