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

[Thiébaud Weksteen]

On Tue, Sep 8, 2026 at 1:24 AM Leon Hwang <leon.hwang@xxxxxxxxx> wrote:
>
> On 2026/9/7 13:46, Thiébaud Weksteen wrote:
> > 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?
> >
>
> imo, the rejection of autoload=false prog when generating light skeleton
> is not friendly for users. Users should not care about mixing
> autoload=false progs with autoload=true progs, even for light skeletons.
>
> The users-friendly way is to skip those autoload=false progs when
> generating light skeletons.

Good point. I agree. I'll send a patch with this approach instead. Thanks.