> On Sat, Mar 26, 2022 at 01:38:36AM +0000, Quentin Monnet wrote:
> 2022-03-09 17:31 UTC+0100 ~ Dmitrii Dolgov <9erthalion6@xxxxxxxxx>
> > Commit 82e6b1eee6a8 ("bpf: Allow to specify user-provided bpf_cookie for
> > BPF perf links") introduced the concept of user specified bpf_cookie,
> > which could be accessed by BPF programs using bpf_get_attach_cookie().
> > For troubleshooting purposes it is convenient to expose bpf_cookie via
> > bpftool as well, so there is no need to meddle with the target BPF
> > program itself.
> >
> > [...]
> >
> > diff --git a/tools/bpf/bpftool/pids.c b/tools/bpf/bpftool/pids.c
> > index 7c384d10e95f..bb6c969a114a 100644
> > --- a/tools/bpf/bpftool/pids.c
> > +++ b/tools/bpf/bpftool/pids.c
> > @@ -78,6 +78,8 @@ static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
> > ref->pid = e->pid;
> > memcpy(ref->comm, e->comm, sizeof(ref->comm));
> > refs->ref_cnt = 1;
> > + refs->has_bpf_cookie = e->has_bpf_cookie;
> > + refs->bpf_cookie = e->bpf_cookie;
> >
> > err = hashmap__append(map, u32_as_hash_field(e->id), refs);
> > if (err)
> > @@ -205,6 +207,9 @@ void emit_obj_refs_json(struct hashmap *map, __u32 id,
> > if (refs->ref_cnt == 0)
> > break;
> >
> > + if (refs->has_bpf_cookie)
> > + jsonw_lluint_field(json_writer, "bpf_cookie", refs->bpf_cookie);
> > +
>
> Thinking again about this patch, shouldn't the JSON output for the
> cookie(s) be an array if we expect to have several cookies for
> multi-attach links in the future?
Interesting point. My impression is that this could be done together
with the other changes about making multi-attach links possible (I
didn't miss anything, it's not yet implemented, right?). On the other
hand I'm planning to prepare few more patches in similar direction -- so
if everyone agrees it has to be extended to an array now, I can tackle
this as well.
