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

From: Yonghong Song <yhs@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.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 19:24:15 -0800	[thread overview]
Message-ID: <75afef04-efaf-a39b-97ce-3cd8d334bfbb@fb.com> (raw)
In-Reply-To: <CAEf4BzY6ih+UKzjhqyTe9JtgO2wSFjt=kOFC6r1r1hYXdBTNtQ@mail.gmail.com>

On 2/25/21 3:25 PM, Andrii Nakryiko wrote:
> 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?

from libbpf.c, I think it should work. Will remove "/"
if it does 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
>>