Re: [PATCH bpf-next v3 5/9] selftests/bpf: Add kfunc __arena and __arena_nullable argument tests

Thank you for your contribution! Sashiko AI review found 1 potential issue(=
s) to consider:
- [Medium] The `arena_arg_stack` test incorrectly wraps its failure-inducin=
g logic in an `#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)` block, which cau=
ses the test to falsely fail on compilers without this feature.
--

--- Patch [5]: [PATCH bpf-next v3 5/9] selftests/bpf: Add kfunc __arena and=
 __arena_nullable argument tests ---
commit b62ba0a2046a4e44e0da5d972133d046f475c161
Author: Tejun Heo <[email protected]>

selftests/bpf: Add kfunc __arena and __arena_nullable argument tests

This commit adds arena-argument kfuncs to bpf_testmod and a corresponding
suite of BPF programs to test various argument forms and rebase semantics.
The tests are intended to run on x86-64 where JIT support exists.

> diff --git a/tools/testing/selftests/bpf/progs/arena_kfunc.c b/tools/test=
ing/selftests/bpf/progs/arena_kfunc.c
> new file mode 100644
> index 0000000000000..e7250c5197ab4
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/arena_kfunc.c
[ ... ]
> +SEC("syscall")
> +__arch_x86_64
> +__failure __msg("arena pointer cannot be a stack argument")
> +int arena_arg_stack(void *ctx)
> +{
> +#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
> +	bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);
> +	bpf_kfunc_arena_stack_arg_test(1, 2, 3, 4, 5, (u64 *)1);
> +#endif

[Severity: Medium]
Will this test incorrectly fail on toolchains without
__BPF_FEATURE_ADDR_SPACE_CAST?

When the feature is missing, the #if block evaluates to false, leaving an
empty program that simply returns 0. The BPF verifier will accept this empty
program, but because the test is annotated with __failure __msg(...), the
test harness expects the verifier to reject it.

Since verification succeeds in this case, does this cause the test harness =
to
flag it as a spurious test failure during CI or user builds?

> +	return 0;
> +}
> +
> +char _license[] SEC("license") =3D "GPL";

--=20
Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260803125115.2264=
[email protected]?part=3D5