Re: [PATCH bpf-next v3] libbpf: Fix expected_attach_type set when kernel not support

[Tao Chen <chen.dylane@gmail.com>]

在 2024/9/25 18:36, Daniel Borkmann 写道:
> On 9/25/24 12:28 PM, Jiri Olsa wrote:
>> On Sat, Sep 14, 2024 at 11:40:40PM +0800, Tao Chen wrote:
>>> The commit "5902da6d8a52" set expected_attach_type again with
>>> field of bpf_program after libpf_prepare_prog_load, which makes
>>> expected_attach_type = 0 no sense when kenrel not support the
>>> attach_type feature, so fix it.
>>>
>>> Fixes: 5902da6d8a52 ("libbpf: Add uprobe multi link support to 
>>> bpf_program__attach_usdt")
>>> Suggested-by: Jiri Olsa <jolsa@kernel.org>
>>> Signed-off-by: Tao Chen <chen.dylane@gmail.com>
>>> ---
>>>   tools/lib/bpf/libbpf.c | 12 ++++++++----
>>>   1 file changed, 8 insertions(+), 4 deletions(-)
>>>
>>> Change list:
>>> - v2 -> v3:
>>>      - update BPF_TRACE_UPROBE_MULTI both in prog and opts suggedted by
>>>        Andrri
>>> - v1 -> v2:
>>>      - restore the original initialization way suggested by Jiri
>>>
>>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>>> index 219facd0e66e..a78e24ff354b 100644
>>> --- a/tools/lib/bpf/libbpf.c
>>> +++ b/tools/lib/bpf/libbpf.c
>>> @@ -7352,8 +7352,14 @@ static int libbpf_prepare_prog_load(struct 
>>> bpf_program *prog,
>>>           opts->prog_flags |= BPF_F_XDP_HAS_FRAGS;
>>>       /* special check for usdt to use uprobe_multi link */
>>> -    if ((def & SEC_USDT) && kernel_supports(prog->obj, 
>>> FEAT_UPROBE_MULTI_LINK))
>>> +    if ((def & SEC_USDT) && kernel_supports(prog->obj, 
>>> FEAT_UPROBE_MULTI_LINK)) {
>>> +        /* for BPF_TRACE_KPROBE_MULTI, user might want to query 
>>> exected_attach_type
>>> +         * in prog, and expected_attach_type we set in kenrel is 
>>> from opts, so we
>>> +         * update both.
>>> +         */
>> s/K/U/ in BPF_TRACE_KPROBE_MULTI in above comment and 'kenrel' typo
>>
>> Acked-by: Jiri Olsa <jolsa@kernel.org>
> Same typo is also in commit desc, would be good to improve the commit
> desc a bit if you spin v4 anyway. Thanks!

Hi，Dnaiel，my bad，i will fix it in v4

-- 
Best Regards
Dylane Chen