Re: [PATCH bpf-next v3 10/11] selftests/bpf: add hashmap test for bpf_for_each_map_elem() helper

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Yonghong Song <yhs@fb.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next v3 10/11] selftests/bpf: add hashmap test for bpf_for_each_map_elem() helper
Date: Thu, 25 Feb 2021 15:25:09 -0800	[thread overview]
Message-ID: <CAEf4BzY6ih+UKzjhqyTe9JtgO2wSFjt=kOFC6r1r1hYXdBTNtQ@mail.gmail.com> (raw)
In-Reply-To: <20210225073320.4121679-1-yhs@fb.com>

On Thu, Feb 25, 2021 at 1:35 AM Yonghong Song <yhs@fb.com> wrote:
>
> A test case is added for hashmap and percpu hashmap. The test
> also exercises nested bpf_for_each_map_elem() calls like
>     bpf_prog:
>       bpf_for_each_map_elem(func1)
>     func1:
>       bpf_for_each_map_elem(func2)
>     func2:
>
>   $ ./test_progs -n 45
>   #45/1 hash_map:OK
>   #45 for_each:OK
>   Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED
>
> Signed-off-by: Yonghong Song <yhs@fb.com>
> ---

I think I'll just add all the variants of ASSERT_XXX and will enforce
their use :)

For now:

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  .../selftests/bpf/prog_tests/for_each.c       | 74 +++++++++++++++
>  .../bpf/progs/for_each_hash_map_elem.c        | 95 +++++++++++++++++++
>  2 files changed, 169 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/for_each.c
>  create mode 100644 tools/testing/selftests/bpf/progs/for_each_hash_map_elem.c
>

[...]

> +
> +       ASSERT_EQ(skel->bss->hashmap_output, 4, "hashmap_output");
> +       ASSERT_EQ(skel->bss->hashmap_elems, max_entries, "hashmap_elems");
> +
> +       key = 1;
> +       err = bpf_map_lookup_elem(hashmap_fd, &key, &val);
> +       ASSERT_ERR(err, "hashmap_lookup");
> +
> +       ASSERT_EQ(skel->bss->percpu_called, 1, "percpu_called");
> +       ASSERT_EQ(skel->bss->cpu < num_cpus, 1, "num_cpus");

well, this is cheating (it will print something like "0 != 1" on
error) :) why didn't you just add ASSERT_LT?

> +       ASSERT_EQ(skel->bss->percpu_map_elems, 1, "percpu_map_elems");
> +       ASSERT_EQ(skel->bss->percpu_key, 1, "percpu_key");
> +       ASSERT_EQ(skel->bss->percpu_val, skel->bss->cpu + 1, "percpu_val");
> +       ASSERT_EQ(skel->bss->percpu_output, 100, "percpu_output");
> +out:
> +       free(percpu_valbuf);
> +       for_each_hash_map_elem__destroy(skel);
> +}
> +
> +void test_for_each(void)
> +{
> +       if (test__start_subtest("hash_map"))
> +               test_hash_map();
> +}

[...]

> +int hashmap_output = 0;
> +int hashmap_elems = 0;
> +int percpu_map_elems = 0;
> +
> +SEC("classifier/")

nit: just "classifier" didn't work?

> +int test_pkt_access(struct __sk_buff *skb)
> +{
> +       struct callback_ctx data;
> +
> +       data.ctx = skb;
> +       data.input = 10;
> +       data.output = 0;
> +       hashmap_elems = bpf_for_each_map_elem(&hashmap, check_hash_elem, &data, 0);
> +       hashmap_output = data.output;
> +
> +       percpu_map_elems = bpf_for_each_map_elem(&percpu_map, check_percpu_elem,
> +                                                (void *)0, 0);
> +       return 0;
> +}
> --
> 2.24.1
>