netdev - Re: [PATCH bpf-next 5/6] selftests/bpf: test BPF_MAP

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Date:   Wed, 24 Jul 2019 14:58:34 -0700
From:   Song Liu <liu.song.a23@...il.com>
To:     Brian Vazquez <brianvv@...gle.com>
Cc:     Brian Vazquez <brianvv.kernel@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S . Miller" <davem@...emloft.net>,
        Stanislav Fomichev <sdf@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Petar Penkov <ppenkov@...gle.com>,
        open list <linux-kernel@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf-next 5/6] selftests/bpf: test BPF_MAP_DUMP command on
 a bpf hashmap

On Wed, Jul 24, 2019 at 10:10 AM Brian Vazquez <brianvv@...gle.com> wrote:
>
> This tests exercise the new command on a bpf hashmap and make sure it
> works as expected.
>
> Signed-off-by: Brian Vazquez <brianvv@...gle.com>
> ---
>  tools/testing/selftests/bpf/test_maps.c | 83 ++++++++++++++++++++++++-
>  1 file changed, 81 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
> index 5443b9bd75ed7..f7ab401399d40 100644
> --- a/tools/testing/selftests/bpf/test_maps.c
> +++ b/tools/testing/selftests/bpf/test_maps.c
> @@ -309,6 +309,86 @@ static void test_hashmap_walk(unsigned int task, void *data)
>         close(fd);
>  }
>
> +static void test_hashmap_dump(void)
> +{
> +       int fd, i, max_entries = 5;

5 is too small for map_dump.

> +       uint64_t keys[max_entries], values[max_entries];
> +       uint64_t key, value, next_key, prev_key;
> +       bool next_key_valid = true;
> +       void *buf, *elem;
> +       u32 buf_len;
> +       const int elem_size = sizeof(key) + sizeof(value);
> +
> +       fd = helper_fill_hashmap(max_entries);
> +
> +       // Get the elements in the hashmap, and store them in that order

Please use /* */ instead of //.

> +       assert(bpf_map_get_next_key(fd, NULL, &key) == 0);
> +       i = 0;
> +       keys[i] = key;
> +       for (i = 1; next_key_valid; i++) {
> +               next_key_valid = bpf_map_get_next_key(fd, &key, &next_key) == 0;
> +               assert(bpf_map_lookup_elem(fd, &key, &values[i - 1]) == 0);
> +               keys[i-1] = key;
> +               key = next_key;
> +       }
> +
> +       // Alloc memory for the whole table
> +       buf = malloc(elem_size * max_entries);
> +       assert(buf != NULL);
> +
> +       // Check that buf_len < elem_size returns EINVAL
> +       buf_len = elem_size-1;
> +       errno = 0;
> +       assert(bpf_map_dump(fd, NULL, buf, &buf_len) == -1 && errno == EINVAL);
> +
> +       // Check that it returns the first two elements
> +       errno = 0;
> +       buf_len = elem_size * 2;
> +       i = 0;
> +       assert(bpf_map_dump(fd, NULL, buf, &buf_len) == 0 &&
> +              buf_len == 2*elem_size);
> +       elem = buf;
> +       assert((*(uint64_t *)elem) == keys[i] &&
> +              (*(uint64_t *)(elem + sizeof(key))) == values[i]);
> +       elem = buf + elem_size;
> +       i++;
> +       assert((*(uint64_t *)elem) == keys[i] &&
> +              (*(uint64_t *)(elem + sizeof(key))) == values[i]);
> +       i++;
> +
> +       /* Check that prev_key contains key from last_elem retrieved in previous
> +        * call
> +        */
> +       prev_key = *((uint64_t *)elem);
> +       assert(bpf_map_dump(fd, &prev_key, buf, &buf_len) == 0 &&
> +              buf_len == elem_size*2);
> +       elem = buf;
> +       assert((*(uint64_t *)elem) == keys[i] &&
> +              (*(uint64_t *)(elem + sizeof(key))) == values[i]);
> +       elem = buf + elem_size;
> +       i++;
> +       assert((*(uint64_t *)elem) == keys[i] &&
> +              (*(uint64_t *)(elem + sizeof(key))) == values[i]);
> +       i++;
> +       assert(prev_key == (*(uint64_t *)elem));
> +
> +       /* Continue reading from map and verify buf_len only contains 1 element
> +        * even though buf_len is 2 elem_size and it returns err = 0.
> +        */
> +       assert(bpf_map_dump(fd, &prev_key, buf, &buf_len) == 0 &&
> +              buf_len == elem_size);
> +       elem = buf;
> +       assert((*(uint64_t *)elem) == keys[i] &&
> +              (*(uint64_t *)(elem + sizeof(key))) == values[i]);
> +
> +       // Verify there's no more entries and err = ENOENT
> +       assert(bpf_map_dump(fd, &prev_key, buf, &buf_len) == -1 &&
> +              errno == ENOENT);
> +
> +       free(buf);
> +       close(fd);
> +}
> +
>  static void test_hashmap_zero_seed(void)
>  {
>         int i, first, second, old_flags;
> @@ -1677,6 +1757,7 @@ static void run_all_tests(void)
>         test_hashmap_percpu(0, NULL);
>         test_hashmap_walk(0, NULL);
>         test_hashmap_zero_seed();
> +       test_hashmap_dump();
>
>         test_arraymap(0, NULL);
>         test_arraymap_percpu(0, NULL);
> @@ -1714,11 +1795,9 @@ int main(void)
>
>         map_flags = BPF_F_NO_PREALLOC;
>         run_all_tests();
> -
>  #define CALL
>  #include <map_tests/tests.h>
>  #undef CALL
> -
>         printf("test_maps: OK, %d SKIPPED\n", skips);
>         return 0;
>  }
> --
> 2.22.0.657.g960e92d24f-goog
>