From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Tao Chen <chen.dylane@linux.dev>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>,
Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
Matt Bobrowski <mattbobrowski@google.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
linux-trace-kernel <linux-trace-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next v4 2/2] bpf: Add show_fdinfo for kprobe_multi
Date: Fri, 20 Jun 2025 11:25:06 -0700 [thread overview]
Message-ID: <CAADnVQ+SgYop50-1S7424ecRKWDM3R=8cHeizRCjeC_FXdkdLA@mail.gmail.com> (raw)
In-Reply-To: <77b09f48-01d9-46f1-8a31-a1824c0eef8d@linux.dev>
On Thu, Jun 19, 2025 at 8:31 PM Tao Chen <chen.dylane@linux.dev> wrote:
>
> 在 2025/6/20 10:59, Alexei Starovoitov 写道:
> > On Thu, Jun 19, 2025 at 7:46 PM Tao Chen <chen.dylane@linux.dev> wrote:
> >>
> >> 在 2025/6/20 01:17, Alexei Starovoitov 写道:
> >>> On Wed, Jun 18, 2025 at 8:44 PM Tao Chen <chen.dylane@linux.dev> wrote:
> >>>>
> >>>> Show kprobe_multi link info with fdinfo, the info as follows:
> >>>>
> >>>> link_type: kprobe_multi
> >>>> link_id: 1
> >>>> prog_tag: a15b7646cb7f3322
> >>>> prog_id: 21
> >>>> type: kprobe_multi
> >>>
> >>> ..
> >>>
> >>>> + seq_printf(seq,
> >>>> + "type:\t%s\n"
> >>>> + "kprobe_cnt:\t%u\n"
> >>>> + "missed:\t%lu\n",
> >>>> + kmulti_link->flags == BPF_F_KPROBE_MULTI_RETURN ? "kretprobe_multi" :
> >>>> + "kprobe_multi",
> >>>
> >>> why print the same info twice ?
> >>> seq_printf(m, "link_type:\t%s\n", bpf_link_type_strs[type]);
> >>> in bpf_link_show_fdinfo() already did it in a cleaner way.
> >>>
> >>
> >> link_type only shows 'kprobe_multi', maybe we can show the format like:
> >
> > Ohh. Especially so. It would be wrong and confusing to display:
> > link_type: kprobe_multi
> > type: kretprobe_multi
> >
> > Let's fix 'link_type' to display it properly.
>
> What do you think show like this:
>
> link_type: kprobe_multi
> link_id: 1
> prog_tag: 33be53a4fd673e1d
> prog_id: 21
> retprobe: false
It leaks implementation details.
For the kernel the link type is BPF_LINK_TYPE_KPROBE_MULTI for retprobe too,
but show_fdinfo is for humans.
'link_type:' field can be more precise and differentiate
what's effectively a subtype of the link.
next prev parent reply other threads:[~2025-06-20 18:25 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-19 3:42 [PATCH bpf-next v4 1/2] bpf: Add show_fdinfo for uprobe_multi Tao Chen
2025-06-19 3:42 ` [PATCH bpf-next v4 2/2] bpf: Add show_fdinfo for kprobe_multi Tao Chen
2025-06-19 17:17 ` Alexei Starovoitov
2025-06-20 2:45 ` Tao Chen
2025-06-20 2:59 ` Alexei Starovoitov
2025-06-20 3:21 ` Tao Chen
2025-06-20 3:31 ` Tao Chen
2025-06-20 18:25 ` Alexei Starovoitov [this message]
2025-06-23 2:32 ` Tao Chen
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