On Sat, Apr 03, 2021 at 01:24:12PM +0200, Toke Høiland-Jørgensen wrote:
> > if (!prog->aux->dst_trampoline && !tgt_prog) {
> > - err = -ENOENT;
> > - goto out_unlock;
> > + /*
> > + * Allow re-attach for tracing programs, if it's currently
> > + * linked, bpf_trampoline_link_prog will fail.
> > + */
> > + if (prog->type != BPF_PROG_TYPE_TRACING) {
> > + err = -ENOENT;
> > + goto out_unlock;
> > + }
> > + if (!prog->aux->attach_btf) {
> > + err = -EINVAL;
> > + goto out_unlock;
> > + }
>
> I'm wondering about the two different return codes here. Under what
> circumstances will aux->attach_btf be NULL, and why is that not an
> ENOENT error? :)
The feature makes sense to me as well.
I don't quite see how it would get here with attach_btf == NULL.
Maybe WARN_ON then?
Also if we're allowing re-attach this way why exclude PROG_EXT and LSM?
