Re: [PATCH bpf-next 2/2] selftests/bpf: Test BPF map creation using BTF-defined key/value

[Hengqi Chen <hengqi.chen@gmail.com>]

On 9/9/21 12:29 PM, Andrii Nakryiko wrote:
> On Sun, Sep 5, 2021 at 3:09 AM Hengqi Chen <hengqi.chen@gmail.com> wrote:
>>
>> Test BPF map creation using BTF-defined key/value. The test defines
>> some specialized maps by specifying BTF types for key/value and
>> checks those maps are correctly initialized and loaded.
>>
>> Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
>> ---
>>  .../selftests/bpf/prog_tests/map_create.c     |  87 ++++++++++++++
>>  .../selftests/bpf/progs/test_map_create.c     | 110 ++++++++++++++++++
>>  2 files changed, 197 insertions(+)
>>  create mode 100644 tools/testing/selftests/bpf/prog_tests/map_create.c
>>  create mode 100644 tools/testing/selftests/bpf/progs/test_map_create.c
>>
>> diff --git a/tools/testing/selftests/bpf/prog_tests/map_create.c b/tools/testing/selftests/bpf/prog_tests/map_create.c
>> new file mode 100644
>> index 000000000000..6ca32d0dffd2
>> --- /dev/null
>> +++ b/tools/testing/selftests/bpf/prog_tests/map_create.c
>> @@ -0,0 +1,87 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/* Copyright (c) 2021 Hengqi Chen */
>> +
>> +#include <test_progs.h>
>> +#include "test_map_create.skel.h"
>> +
>> +void test_map_create(void)
>> +{
>> +       struct test_map_create *skel;
>> +       int err, fd;
>> +
>> +       skel = test_map_create__open();
>> +       if (!ASSERT_OK_PTR(skel, "test_map_create__open failed"))
>> +               return;
>> +
>> +       err = test_map_create__load(skel);
> 
> If load() succeeds, all the maps will definitely be created, so all
> the below tests are meaningless.
> 
> I think it's better to just change all the existing map definitions
> used throughout selftests to use key/value types, instead of
> key_size/value_size. That will automatically test this feature without
> adding an extra test. Unfortunately to really test that the logic is
> working, we'd need to check that libbpf doesn't emit the warning about
> retrying map creation w/o BTF, but I think one-time manual check
> (please use ./test_progs -v to see libbpf warnings during tests)
> should be sufficient for this.
> 

Hello, Andrii

I updated these existing tests as you suggested, 
but I was unable to run the whole bpf selftests locally.

Running ./test_progs -v made my system hang up,
didn't find the root cause yet.

Instead I just run the modified test with the following commands:

sudo ./test_progs -v --name=kfree_skb,perf_event_stackmap,btf_map_in_map,pe_preserve_elems,stacktrace_map,stacktrace_build_id,xdp_bpf2bpf,select_reuseport,tcpbpf_user

>> +       if (!ASSERT_OK(err, "test_map_create__load failed"))
>> +               goto cleanup;
>> +
>> +       fd = bpf_map__fd(skel->maps.map1);
>> +       if (!ASSERT_GT(fd, 0, "bpf_map__fd failed"))
>> +               goto cleanup;
>> +       close(fd);
>> +
>> +       fd = bpf_map__fd(skel->maps.map2);
>> +       if (!ASSERT_GT(fd, 0, "bpf_map__fd failed"))
>> +               goto cleanup;
>> +       close(fd);
> 
> [...]
>