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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.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>,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	Andrii Nakryiko <andriin@fb.com>
Subject: Re: [PATCH bpf-next] libbpf: Add support for dynamic program attach target
Date: Wed, 12 Feb 2020 09:35:26 -0800
Message-ID: <CAEf4BzYn3pVhqzj8PwRWxjWSJ16CS9d60zFtsS=OuA5ydPyp2Q@mail.gmail.com> (raw)
In-Reply-To: <874kvwhs6u.fsf@toke.dk>

On Wed, Feb 12, 2020 at 5:05 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Eelco Chaudron <echaudro@redhat.com> writes:
>
> > 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");
>
> I think it would be better to have the attach type as a separate arg
> instead of encoding it in the function name. I.e., rather:
>
>    bpf_program__set_attach_target(prog, xdp_fd,
>                                   "xdpfilt_blk_all", BPF_TRACE_FENTRY);

I agree about not specifying section name prefix (e.g., fentry/). But
disagree that expected attach type (BPF_TRACE_FENTRY) should be part
of this API. We already have bpf_program__set_expected_attach_type()
API, no need to duplicate it here.

>
> -Toke
>

  reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 12:31 Eelco Chaudron
2020-02-12 13:05 ` Toke Høiland-Jørgensen
2020-02-12 17:35   ` Andrii Nakryiko [this message]
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
2020-02-12 18:34         ` Andrii Nakryiko
2020-02-12 18:40           ` Song Liu

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