On Sat, Apr 03, 2021 at 11:21:55AM -0700, Alexei Starovoitov wrote:
> 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?
right, that should be always there
> Also if we're allowing re-attach this way why exclude PROG_EXT and LSM?
>
I was enabling just what I needed for the test, which is so far
the only use case.. I'll see if I can enable that for all of them
jirka
