> > From: Toke Hoiland-Jorgensen <toke@redhat.com>
> > 
> > The check for tail call map compatibility ensures that tail calls only
> > happen between maps of the same type. To ensure backwards compatibility for
> > XDP multi-buffer we need a similar type of check for cpumap and devmap
> > programs, so move the state from bpf_array_aux into bpf_map, add xdp_mb to
> > the check, and apply the same check to cpumap and devmap.
> > 
> > Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > Signed-off-by: Toke Hoiland-Jorgensen <toke@redhat.com>
> > ---
> 
> ...
> 
> > -bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
> > +static inline bool map_type_contains_progs(struct bpf_map *map)
> 
> Maybe map_type_check_needed()? Just noticing that devmap doesn't contain
> progs.

ack, I am fine with it. Toke?

> 
> > +{
> > +	return map->map_type == BPF_MAP_TYPE_PROG_ARRAY ||
> > +	       map->map_type == BPF_MAP_TYPE_DEVMAP ||
> > +	       map->map_type == BPF_MAP_TYPE_CPUMAP;
> > +}
> > +
> > +bool bpf_prog_map_compatible(struct bpf_map *map, const struct bpf_prog *fp);
> >  int bpf_prog_calc_tag(struct bpf_prog *fp);
> 
> Otherwise LGTM.
>