From: Song Liu <songliubraving@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: "Eelco Chaudron" <echaudro@redhat.com>, bpf <bpf@vger.kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Networking <netdev@vger.kernel.org>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Martin Lau" <kafai@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Andrii Nakryiko" <andriin@fb.com>,
"Toke Høiland-Jørgensen" <toke@redhat.com>
Subject: Re: [PATCH bpf-next] libbpf: Add support for dynamic program attach target
Date: Wed, 12 Feb 2020 18:28:43 +0000 [thread overview]
Message-ID: <F37F13F4-DAFE-4431-804F-BF7940D9970D@fb.com> (raw)
In-Reply-To: <CAEf4BzYFVtgW4Zyz09vuppAJA3oQ-UAT4yALeFJk2JQ70+mE2g@mail.gmail.com>
> On Feb 12, 2020, at 10:14 AM, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
>
> On Wed, Feb 12, 2020 at 10:07 AM Song Liu <songliubraving@fb.com> wrote:
>>
>>
>>
>>> On Feb 12, 2020, at 9:34 AM, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
>>>
>>> On Wed, Feb 12, 2020 at 4:32 AM Eelco Chaudron <echaudro@redhat.com> wrote:
>>>>
>>>> Currently when you want to attach a trace program to a bpf program
>>>> the section name needs to match the tracepoint/function semantics.
>>>>
>>>> However the addition of the bpf_program__set_attach_target() API
>>>> allows you to specify the tracepoint/function dynamically.
>>>>
>>>> The call flow would look something like this:
>>>>
>>>> xdp_fd = bpf_prog_get_fd_by_id(id);
>>>> trace_obj = bpf_object__open_file("func.o", NULL);
>>>> prog = bpf_object__find_program_by_title(trace_obj,
>>>> "fentry/myfunc");
>>>> bpf_program__set_attach_target(prog, xdp_fd,
>>>> "fentry/xdpfilt_blk_all");
>>>> bpf_object__load(trace_obj)
>>>>
>>>> Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
>>
>>
>> I am trying to solve the same problem with slightly different approach.
>>
>> It works as the following (with skeleton):
>>
>> obj = myobject_bpf__open_opts(&opts);
>> bpf_object__for_each_program(prog, obj->obj)
>> bpf_program__overwrite_section_name(prog, new_names[id++]);
>> err = myobject_bpf__load(obj);
>>
>> I don't have very strong preference. But I think my approach is simpler?
>
> I prefer bpf_program__set_attach_target() approach. Section name is a
> program identifier and a *hint* for libbpf to determine program type,
> attach type, and whatever else makes sense. But there still should be
> an API to set all that manually at runtime, thus
> bpf_program__set_attach_target(). Doing same by overriding section
> name feels like a hack, plus it doesn't handle overriding
> attach_program_fd at all.
We already have bpf_object_open_opts to handle different attach_program_fd.
Can we depreciate bpf_object_open_opts.attach_prog_fd with the
bpf_program__set_attach_target() approach?
Thanks,
Song
next prev parent reply other threads:[~2020-02-12 18:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 12:31 [PATCH bpf-next] libbpf: Add support for dynamic program attach target Eelco Chaudron
2020-02-12 13:05 ` Toke Høiland-Jørgensen
2020-02-12 17:35 ` Andrii Nakryiko
2020-02-12 21:52 ` Toke Høiland-Jørgensen
2020-02-13 14:41 ` Eelco Chaudron
2020-02-12 17:34 ` Andrii Nakryiko
2020-02-12 17:56 ` Song Liu
2020-02-12 18:14 ` Andrii Nakryiko
2020-02-12 18:28 ` Song Liu [this message]
2020-02-12 18:34 ` Andrii Nakryiko
2020-02-12 18:40 ` Song Liu
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