Re: [PATCH bpf-next 1/2] selftests/bpf: Move verifier failure tests out of test_global_percpu_data

[Thiébaud Weksteen]

On Fri, Sep 4, 2026 at 4:07 PM Leon Hwang <leon.hwang@xxxxxxxxx> wrote:
>
> On 4/9/26 11:19, Thiébaud Weksteen wrote:
> > Commit 4c9241bd731a ("selftests/bpf: Add tests to verify global percpu
> > data") added test_global_percpu_data.c to LSKELS_EXTRA. Later, in commit
> > 1ed2294b31fc ("selftests/bpf: Test verifier log for global percpu data")
> > two verifier failure tests were added (verifier_strncmp and
> > verifier_snprintf), both marked as non-autoload (SEC("?kprobe")).
> >
> > When bpftool generates light skeletons, non-autoloaded programs are
> > skipped during loading, causing the loader program to store subsequent
> > program FDs into incorrect skeleton struct fields (e.g. dump_percpu_data's
> > FD was stored into verifier_strncmp's descriptor).
>
> IIUC, patch 2 will fix the issue totally.
>
> Better to add a subtest to verify both the issue and the fix?

Thanks for the review. That's right, patch 2 will fix the issue:
bpftool will fail to build any program that is set up that way. That's
why patch 1 is necessary; otherwise, the existing test would fail.

Just checking your suggestion: what I can do is add a new test to make
sure that dump_percpu_data is set up as expected (fd > 0). I can write
a new test_global_percpu_data_iter_lskel, that is similar to
test_global_percpu_data_iter, but for lskel?

I can also write a test to ensure that bpftool fails when light
skeletons are set up with autoload=false?

Thanks,