Re: [PATCH bpf-next 1/2] bpftool: improve skeleton backwards compat with old buggy libbpfs

[Eduard Zingerman <eddyz87@gmail.com>]

On Mon, 2024-07-08 at 10:15 -0700, Andrii Nakryiko wrote:

[...]

> > static inline int
> > profiler_bpf__create_skeleton(struct profiler_bpf *obj)
> > {
> >         /* ... */
> > 
> >         map = (struct bpf_map_skeleton *)((char *)s->maps + 0 * s->map_skel_sz);
> >         map->name = "events";
> >         map->map = &obj->maps.events;
> > 
> >         /* ... 4 more like this ... */
> > 
> >         /* ... */
> > 
> >         s->progs[0].name = "fentry_XXX";
> >         s->progs[0].prog = &obj->progs.fentry_XXX;
> >         s->progs[0].link = &obj->links.fentry_XXX;
> > 
> >         s->progs[1].name = "fexit_XXX";
> >         s->progs[1].prog = &obj->progs.fexit_XXX;
> >         s->progs[1].link = &obj->links.fexit_XXX;
> > 
> >         /* ... */
> > }
> > 
> > Do we need to handle 'progs' array access in a same way as maps?
> 
> Given bpf_prog_skeleton has never been extended yet (and maybe never
> will be), I chose not to uglify this unnecessarily. My thinking/hope
> is that by the time we get to extending prog_skeleton struct, all
> actively used libbpf versions will be patched up and will handle this
> correctly without the hacks we have to do for map_skeleton.

Understood, fair enough.

[...]