netdev - Re: [PATCHv4 bpf-next 6/8] libbpf: Add bpf_program__attach_kprobe

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Message-ID: <CAEf4Bzbk-nyenpc86jtEShset_ZSkapvpy3fG2gYKZEOY7uAQg@mail.gmail.com>
Date:   Fri, 16 Jul 2021 18:41:59 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alan Maguire <alan.maguire@...cle.com>
Subject: Re: [PATCHv4 bpf-next 6/8] libbpf: Add bpf_program__attach_kprobe_opts
 function

On Wed, Jul 14, 2021 at 2:45 AM Jiri Olsa <jolsa@...hat.com> wrote:
>
> Adding bpf_program__attach_kprobe_opts that does the same
> as bpf_program__attach_kprobe, but takes opts argument.
>
> Currently opts struct holds just retprobe bool, but we will
> add new field in following patch.
>
> The function is not exported, so there's no need to add
> size to the struct bpf_program_attach_kprobe_opts for now.

Why not exported? Please use a proper _opts struct just like others
(e.g., bpf_object_open_opts) and add is as a public API, it's a useful
addition. We are going to have a similar structure for attach_uprobe,
btw. Please send a follow up patch.

>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/lib/bpf/libbpf.c | 34 +++++++++++++++++++++++++---------
>  1 file changed, 25 insertions(+), 9 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 88b99401040c..d93a6f9408d1 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -10346,19 +10346,24 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
>         return pfd;
>  }
>
> -struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
> -                                           bool retprobe,
> -                                           const char *func_name)
> +struct bpf_program_attach_kprobe_opts {

when you make it part of libbpf API, let's call it something shorter,
like bpf_kprobe_opts, maybe? And later we'll have bpf_uprobe_opts for
uprobes. Short and unambiguous.

> +       bool retprobe;
> +};
> +
> +static struct bpf_link*
> +bpf_program__attach_kprobe_opts(struct bpf_program *prog,
> +                               const char *func_name,
> +                               struct bpf_program_attach_kprobe_opts *opts)
>  {
>         char errmsg[STRERR_BUFSIZE];
>         struct bpf_link *link;
>         int pfd, err;
>

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