Re: [PATCH bpf-next v4 2/2] bpf: Add show_fdinfo for kprobe_multi

[Tao Chen]

在 2025/6/21 02:25, Alexei Starovoitov 写道:
> On Thu, Jun 19, 2025 at 8:31 PM Tao Chen <chen.dylane@xxxxxxxxx> wrote:
> > 在 2025/6/20 10:59, Alexei Starovoitov 写道:
> > > On Thu, Jun 19, 2025 at 7:46 PM Tao Chen <chen.dylane@xxxxxxxxx> wrote:
> > > > 在 2025/6/20 01:17, Alexei Starovoitov 写道:
> > > > > On Wed, Jun 18, 2025 at 8:44 PM Tao Chen <chen.dylane@xxxxxxxxx> 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.

Well, i will fix it in v5. Thanks.

--
Best Regards
Tao Chen