> On Dec 7, 2021, at 3:02 PM, Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Mon, Dec 6, 2021 at 10:30 PM Song Liu <songliubraving@xxxxxx> wrote:
>>
>>
>>
>>> On Dec 6, 2021, at 9:13 PM, Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote:
>>>
>>> On Mon, Dec 6, 2021 at 8:32 PM Song Liu <songliubraving@xxxxxx> wrote:
>>>>
>>>>
>>>>
>>>>> On Dec 6, 2021, at 6:37 PM, Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote:
>>>>>
>>>>> On Mon, Dec 6, 2021 at 3:08 PM Song Liu <song@xxxxxxxxxx> wrote:
>>>>>>
>>>>>> bpf_create_map is deprecated. Replace it with bpf_map_create.
>>>>>>
>>>>>> Fixes: 992c4225419a ("libbpf: Unify low-level map creation APIs w/ new bpf_map_create()")
>>>>>
>>>>> This is not a bug fix, it's an improvement. So I don't think "Fixes: "
>>>>> is warranted here, tbh.
>>>>
>>>> I got compilation errors before this change, like
>>>>
>>>> util/bpf_counter.c: In function ‘bperf_lock_attr_map’:
>>>> util/bpf_counter.c:323:3: error: ‘bpf_create_map’ is deprecated: libbpf v0.7+: use bpf_map_create() instead [-Werror=deprecated-declarations]
>>>> map_fd = bpf_create_map(BPF_MAP_TYPE_HASH,
>>>> ^~~~~~
>>>> In file included from util/bpf_counter.h:7,
>>>> from util/bpf_counter.c:15:
>>>> /data/users/songliubraving/kernel/linux-git/tools/lib/bpf/bpf.h:91:16: note: declared here
>>>> LIBBPF_API int bpf_create_map(enum bpf_map_type map_type, int key_size,
>>>> ^~~~~~~~~~~~~~
>>>> cc1: all warnings being treated as errors
>>>> make[4]: *** [/data/users/songliubraving/kernel/linux-git/tools/build/Makefile.build:96: util/bpf_counter.o] Error 1
>>>> make[4]: *** Waiting for unfinished jobs....
>>>> make[3]: *** [/data/users/songliubraving/kernel/linux-git/tools/build/Makefile.build:139: util] Error 2
>>>> make[2]: *** [Makefile.perf:665: perf-in.o] Error 2
>>>> make[1]: *** [Makefile.perf:240: sub-make] Error 2
>>>> make: *** [Makefile:70: all] Error 2
>>>>
>>>
>>> Hmm.. is util/bpf_counter.h guarded behind some Makefile arguments?
>>> I've sent #pragma temporary workarounds just a few days ago ([0]), but
>>> this one didn't come up during the build.
>>>
>>> [0] https://patchwork.kernel.org/project/netdevbpf/patch/20211203004640.2455717-1-andrii@xxxxxxxxxx/
>>
>> I guess the default build test doesn't enable BUILD_BPF_SKEL?
>
> I see, right, I think I already asked about that before :( Is it
> possible to set Makefile such that it will do BUILD_BPF_SKEL=1 if
> Clang version is recent enough and other conditions are satisfied
> (unless overridden or something)?
Arnaldo is working on this. I guess we can flip the default soon.
>
>>
>>>
>>>> Do we plan to remove bpf_create_map in the future? If not, we can probably just
>>>> add '#pragma GCC diagnostic ignored "-Wdeprecated-declarations"' can call it done?
>>>
>>> Yes, it will be removed in a few libbpf releases when we switch to the
>>> 1.0 version. So suppressing a warning is a temporary work-around.
>>>
>>>>
>>>>>
>>>>>> Signed-off-by: Song Liu <song@xxxxxxxxxx>
>>>>>> ---
>>>>>> tools/perf/util/bpf_counter.c | 4 ++--
>>>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
>>>>>> index c17d4a43ce065..ed150a9b3a0c0 100644
>>>>>> --- a/tools/perf/util/bpf_counter.c
>>>>>> +++ b/tools/perf/util/bpf_counter.c
>>>>>> @@ -320,10 +320,10 @@ static int bperf_lock_attr_map(struct target *target)
>>>>>> }
>>>>>>
>>>>>> if (access(path, F_OK)) {
>>>>>> - map_fd = bpf_create_map(BPF_MAP_TYPE_HASH,
>>>>>> + map_fd = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
>>>>>
>>>>> I think perf is trying to be linkable with libbpf as a shared library,
>>>>> so on some older versions of libbpf bpf_map_create() won't be (yet)
>>>>> available. So to make this work, I think you'll need to define your
>>>>> own weak bpf_map_create function that will use bpf_create_map().
>>>>
>>>> Hmm... I didn't know the plan to link libbpf as shared library. In this case,
>>>> maybe the #pragma solution is preferred?
>>>
>>> See "perf tools: Add more weak libbpf functions" sent by Jiri not so
>>> long ago about what they did with some other used APIs that are now
>>> marked deprecated.
>>
>> Do you mean something like this?
>>
>> int __weak
>> bpf_map_create(enum bpf_map_type map_type,
>> const char *map_name __maybe_unused,
>> __u32 key_size,
>> __u32 value_size,
>> __u32 max_entries,
>> const struct bpf_map_create_opts *opts __maybe_unused)
>> {
>> #pragma GCC diagnostic push
>> #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
>> return bpf_create_map(map_type, key_size, value_size, max_entries, 0);
>> #pragma GCC diagnostic pop
>> }
>>
>> I guess this won't work when bpf_create_map() is eventually removed, as
>> __weak function are still compiled, no?
>
> Yes and yes. I'm not sure what would be perf's plan w.r.t. libbpf 1.0,
> we'll need to work together to figure this out. At some point perf
> will need to say that the minimum version of supported libbpf is v0.6
> or something and just assume all those newer APIs are there (no need
> to bump it all the way to libbpf 1.0, btw).
OK. I will send this version. And we can decide the next step when we
remove bpf_create_map().
Thanks,
Song
