On Wed, Jun 17, 2020 at 5:25 PM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote:
>
> 2020-06-17 09:18 UTC-0700 ~ Andrii Nakryiko <andriin@xxxxxx>
> > Add statements about bpftool being able to discover process info, holding
> > reference to BPF map, prog, link, or BTF. Show example output as well.
> >
> > Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
> > ---
> > tools/bpf/bpftool/Documentation/bpftool-btf.rst | 5 +++++
> > tools/bpf/bpftool/Documentation/bpftool-link.rst | 13 ++++++++++++-
> > tools/bpf/bpftool/Documentation/bpftool-map.rst | 8 +++++++-
> > tools/bpf/bpftool/Documentation/bpftool-prog.rst | 11 +++++++++++
> > 4 files changed, 35 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/Documentation/bpftool-btf.rst b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> > index ce3a724f50c1..85f7c82ebb28 100644
> > --- a/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> > +++ b/tools/bpf/bpftool/Documentation/bpftool-btf.rst
> > @@ -36,6 +36,11 @@ DESCRIPTION
> > otherwise list all BTF objects currently loaded on the
> > system.
> >
> > + Since Linux 5.8 bpftool is able to discover information about
> > + processes that hold open file descriptors (FDs) against BPF
> > + links. On such kernels bpftool will automatically emit this
>
> Copy-paste error: s/BPF links/BTF objects/
>
oops, will fix
> > + information as well.
> > +
> > **bpftool btf dump** *BTF_SRC*
> > Dump BTF entries from a given *BTF_SRC*.
> >
> > diff --git a/tools/bpf/bpftool/Documentation/bpftool-link.rst b/tools/bpf/bpftool/Documentation/bpftool-link.rst
> > index 0e43d7b06c11..1da7ef65b514 100644
> > --- a/tools/bpf/bpftool/Documentation/bpftool-link.rst
> > +++ b/tools/bpf/bpftool/Documentation/bpftool-link.rst
> > @@ -37,6 +37,11 @@ DESCRIPTION
> > zero or more named attributes, some of which depend on type
> > of link.
> >
> > + Since Linux 5.8 bpftool is able to discover information about
> > + processes that hold open file descriptors (FDs) against BPF
> > + links. On such kernels bpftool will automatically emit this
> > + information as well.
> > +
> > **bpftool link pin** *LINK* *FILE*
> > Pin link *LINK* as *FILE*.
> >
> > @@ -82,6 +87,7 @@ EXAMPLES
> >
> > 10: cgroup prog 25
> > cgroup_id 614 attach_type egress
> > + pids test_progs(2238417)
>
> (That's a big PID. Maybe something below the default max pid (32768)
> might be less confusing for users, but also maybe that's just me
> nitpicking too much.)
heh, real system, but yeah, I can make up a smaller PID :)
>
> >
> > **# bpftool --json --pretty link show**
> >
> > @@ -91,7 +97,12 @@ EXAMPLES
> > "type": "cgroup",
> > "prog_id": 25,
> > "cgroup_id": 614,
> > - "attach_type": "egress"
> > + "attach_type": "egress",
> > + "pids": [{
> > + "pid": 2238417,
> > + "comm": "test_progs"
> > + }
> > + ]
> > }
> > ]
> >
