Subject: Re: [PATCH bpf-next 4/4] selftests/bpf: Remove tests for prologue/epilogue with kfuncs

From: Martin KaFai Lau <[email-masked]>
Date: Wed, 21 Jan 2026 11:13:29 -0800

On 1/21/26 1:49 AM, Jakub Sitnicki wrote:
> On Tue, Jan 20, 2026 at 03:48 PM -08, Martin KaFai Lau wrote:
>> On 1/19/26 11:53 AM, Jakub Sitnicki wrote:
>>> Remove pro_epilogue_with_kfunc test program and its supporting code in
>>> bpf_testmod. This test exercised calling kfuncs from prologue and epilogue,
>>> which is no longer supported after the switch to direct helper calls.
>>
>> Is it easy to change it to test calling helper in pro/epilogue?
> 
> I gave it a shot and the obstacle is that bpf_cgroup_from_id and
> bpf_cgroup_release are not exported symbols, so they can't be referred
> to from bpf_testmod. We'd have to move the whole thing to lib/test_bpf
> so it's a built-in.

I was thinking of creating a helper in bpf_testmod.c but then noticed it 
may fail in the JIT that needs bpf_jit_supports_far_kfunc_call(). A 
cleaner way could be to use the existing pro/epilogue in bpf_qdisc ops. 
I was wondering if the __xlated test here could be quickly adapted in 
patch 4 but it seems that's not the case. The existing bpf_qdisc is 
testing it quietly without the __xlated, so no need to hold up this set.

For patch 3 and 4,

Acked-by: Martin KaFai Lau <[email-masked]>