linux-kernel - Re: [PATCH bpf-next v3] libbpf: Fix expected_attach

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Message-ID: <680bbf09-6939-4056-bfc2-27138a93efe6@gmail.com>
Date: Wed, 25 Sep 2024 22:55:00 +0800
From: Tao Chen <chen.dylane@...il.com>
To: Daniel Borkmann <daniel@...earbox.net>, Jiri Olsa <olsajiri@...il.com>
Cc: Andrii Nakryiko <andrii@...nel.org>, Eduard Zingerman
 <eddyz87@...il.com>, Martin KaFai Lau <martin.lau@...ux.dev>,
 Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>,
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>,
 bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v3] libbpf: Fix expected_attach_type set when
 kernel not support

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@...nel.org>
>>> Signed-off-by: Tao Chen <chen.dylane@...il.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@...nel.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