Re: [PATCH bpf-next] selftests/bpf: Add -Wuninitialized flag to bpf prog flags

[David Vernet <void@manifault.com>]

On Thu, Mar 02, 2023 at 03:23:22PM -0800, Alexei Starovoitov wrote:
> On Thu, Mar 2, 2023 at 3:19 PM Dave Marchevsky <davemarchevsky@fb.com> wrote:
> >
> > --- a/tools/testing/selftests/bpf/progs/rbtree_fail.c
> > +++ b/tools/testing/selftests/bpf/progs/rbtree_fail.c
> > @@ -232,8 +232,9 @@ long rbtree_api_first_release_unlock_escape(void *ctx)
> >
> >         bpf_spin_lock(&glock);
> >         res = bpf_rbtree_first(&groot);
> > -       if (res)
> > -               n = container_of(res, struct node_data, node);
> > +       if (!res)
> > +               return -1;
> 
> The verifier cannot be ok with this return... I hope...

This is a negative testcase which correctly fails, though the error
message wasn't what I was expecting to see:

__failure __msg("rbtree_remove node input must be non-owning ref")

Something about the lock still being held seems much more intuitive.

> 
> > +       n = container_of(res, struct node_data, node);
> >         bpf_spin_unlock(&glock);