Re: libbpf: pinning multiple progs from the same section

[Gilad Reti <gilad.reti@gmail.com>]

On Mon, Feb 8, 2021 at 1:42 PM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Gilad Reti <gilad.reti@gmail.com> writes:
>
> > Also, is there a way to set the pin path to all maps/programs at once?
> > For example, bpf_object__pin_maps pins all maps at a specific path,
> > but as far as I was able to find there is no similar function to set
> > the pin path for all maps only (without pinning) so that at loading
> > time libbpf will try to reuse all maps. The only way to achieve a
> > complete reuse of all maps that I could find is to "reverse engineer"
> > libbpf's pin path generation algorithm (i.e. <path>/<map_name>) and
> > set the pin path on each map before load.
>
> You can set the 'pinning' attribute in the map definition - add
> '__uint(pinning, LIBBPF_PIN_BY_NAME);' to the map struct. By default
> this will pin beneath /sys/fs/bpf, but you can customise that by setting
> the pin_root_path attribute in bpf_object_open_opts.

Yes, I am familiar with that feature, but it has some downsides:
1. I need to set it manually on every map (and in cases that I have
only the compiled object file that would be hard).
2. It only works for bpf maps and not bpf programs.
3. It only works for bpf maps that are defined explicitly in the bpf
code and not for implicit (inner) bpf maps (bss, rodata, etc).

>
> -Toke
>