On Wed, 7 Nov 2018 13:00:09 -0800, Stanislav Fomichev wrote:
> > > + }
> > > +
> > > + if (attr.prog_type == BPF_PROG_TYPE_FLOW_DISSECTOR) {
> > > + err = build_flow_dissector_jmp_table(obj, prog, "jmp_table");
> > > + if (err) {
> > > + p_err("failed to build flow dissector jump table");
> > > + goto err_close_obj;
> > > + }
> > > + /* flow dissector consist of multiple programs,
> > > + * we want to pin them all
> >
> > Why pin them all shouldn't the main program be the only one pinned?
> If I pin only the main program, the tail ones disappear from the jmp_table map
> when bpftool exits.
> Am I missing something?
> Should BPF_MAP_TYPE_PROG_ARRAY hold the referenced progs?
It does.
# bpftool map create /sys/fs/bpf/map \
type prog_array key 4 value 4 entries 4 \
name tail_call_map
# bpftool prog load perf_event_output_stack.o /sys/fs/bpf/prog \
type xdp
# bpftool map update pinned /sys/fs/bpf/map \
key 0 0 0 0 \
value pinned /sys/fs/bpf/prog
# bpftool prog
11: xdp name xdp_prog1 tag 6f1b482b27443edf gpl
loaded_at 2018-11-07T13:09:20-0800 uid 0
xlated 144B jited 130B memlock 4096B map_ids 14
# rm /sys/fs/bpf/prog
# bpftool prog
11: xdp name xdp_prog1 tag 6f1b482b27443edf gpl
loaded_at 2018-11-07T13:09:20-0800 uid 0
xlated 144B jited 130B memlock 4096B map_ids 14
# rm /sys/fs/bpf/map
# bpftool prog
# bpftool prog show id 11
Error: get by id (11): No such file or directory
I think we should remove all this auto tail call construction unless
we have solid annotations in the elf file which can clearly guide the
loader.
