Re: [v2 PATCH bpf-next 2/2] bpf/selftests: Check errno when percpu map value size exceeds

[Andrii Nakryiko]

On Mon, Sep 9, 2024 at 12:14 AM Tao Chen <chen.dylane@xxxxxxxxx> wrote:
>
> This test case checks the errno message when percpu map value size
> exceeds PCPU_MIN_UNIT_SIZE.
>
> root@debian:~# ./test_progs -t map_init
>  #160/1   map_init/pcpu_map_init:OK
>  #160/2   map_init/pcpu_lru_map_init:OK
>  #160/3   map_init/pcpu map value size:OK
>  #160     map_init:OK
> Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED
>
> Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx>
> Signed-off-by: jinke han <jinkehan@xxxxxxxxxxxxxx>
> ---
>  .../selftests/bpf/prog_tests/map_init.c       | 32 +++++++++++++++++++
>  .../selftests/bpf/progs/test_map_init.c       |  6 ++++
>  2 files changed, 38 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/map_init.c b/tools/testing/selftests/bpf/prog_tests/map_init.c
> index 14a31109dd0e..7f1a6fa3679f 100644
> --- a/tools/testing/selftests/bpf/prog_tests/map_init.c
> +++ b/tools/testing/selftests/bpf/prog_tests/map_init.c
> @@ -6,6 +6,7 @@
>
>  #define TEST_VALUE 0x1234
>  #define FILL_VALUE 0xdeadbeef
> +#define PCPU_MIN_UNIT_SIZE 32768
>
>  static int nr_cpus;
>  static int duration;
> @@ -118,6 +119,35 @@ static int check_values_one_cpu(pcpu_map_value_t *value, map_value_t expected)
>
>         return 0;
>  }
> +/*
> + * percpu map value size is bound by PCPU_MIN_UNIT_SIZE
> + * check the errno when the value exceed PCPU_MIN_UNIT_SIZE
> + */
> +static void test_pcpu_map_value_size(void)
> +{
> +       struct test_map_init *skel;
> +       int err;
> +       int value_sz = PCPU_MIN_UNIT_SIZE + 1;
> +       enum bpf_map_type map_types[] = { BPF_MAP_TYPE_PERCPU_ARRAY,
> +                                         BPF_MAP_TYPE_PERCPU_HASH,
> +                                         BPF_MAP_TYPE_LRU_PERCPU_HASH };
> +       for (int i = 0; i < ARRAY_SIZE(map_types); i++) {
> +               skel = test_map_init__open();
> +               if (!ASSERT_OK_PTR(skel, "skel_open"))
> +                       return;
> +               err = bpf_map__set_type(skel->maps.hashmap2, map_types[i]);
> +               if (!ASSERT_OK(err, "bpf_map__set_type"))
> +                       goto error;
> +               err = bpf_map__set_value_size(skel->maps.hashmap2, value_sz);
> +               if (!ASSERT_OK(err, "bpf_map__set_value_size"))
> +                       goto error;
> +
> +               err = test_map_init__load(skel);
> +               ASSERT_EQ(err, -E2BIG, "skel_load");

This is quite an overkill to test map creation. It will be much more
straightforward to just use low-level bpf_map_create() API, can you
please make use of that instead?

pw-bot: cr

> +error:
> +               test_map_init__destroy(skel);
> +       }
> +}
>
>  /* Add key=1 elem with values set for all CPUs
>   * Delete elem key=1
> @@ -211,4 +241,6 @@ void test_map_init(void)
>                 test_pcpu_map_init();
>         if (test__start_subtest("pcpu_lru_map_init"))
>                 test_pcpu_lru_map_init();
> +       if (test__start_subtest("pcpu map value size"))
> +               test_pcpu_map_value_size();
>  }
> diff --git a/tools/testing/selftests/bpf/progs/test_map_init.c b/tools/testing/selftests/bpf/progs/test_map_init.c
> index c89d28ead673..7a772cbf0570 100644
> --- a/tools/testing/selftests/bpf/progs/test_map_init.c
> +++ b/tools/testing/selftests/bpf/progs/test_map_init.c
> @@ -15,6 +15,12 @@ struct {
>         __type(value, __u64);
>  } hashmap1 SEC(".maps");
>
> +struct {
> +       __uint(type, BPF_MAP_TYPE_HASH);
> +       __uint(max_entries, 1);
> +       __type(key, __u32);
> +       __type(value, __u64);
> +} hashmap2 SEC(".maps");
>
>  SEC("tp/syscalls/sys_enter_getpgid")
>  int sysenter_getpgid(const void *ctx)
> --
> 2.25.1
>