Re: [PATCH bpf-next v2 11/13] selftests/bpf: Migrate struct_ops_assoc test to KF_IMPLICIT_ARGS

[Eduard Zingerman]

On Tue, 2026-01-20 at 10:20 -0800, Ihor Solodrai wrote:
> On 1/19/26 5:59 PM, Eduard Zingerman wrote:
> > On Fri, 2026-01-16 at 12:16 -0800, Ihor Solodrai wrote:
> > 
> > [...]
> > 
> > > diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
> > > index 2357a0340ffe..225ea30c4e3d 100644
> > > --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
> > > +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
> > > @@ -161,7 +161,9 @@ void bpf_kfunc_rcu_task_test(struct task_struct *ptr) __ksym;
> > >  struct task_struct *bpf_kfunc_ret_rcu_test(void) __ksym;
> > >  int *bpf_kfunc_ret_rcu_test_nostruct(int rdonly_buf_size) __ksym;
> > >  
> > > -int bpf_kfunc_multi_st_ops_test_1(struct st_ops_args *args, u32 id) __ksym;
> > > -int bpf_kfunc_multi_st_ops_test_1_impl(struct st_ops_args *args, void *aux__prog) __ksym;
> > > +#ifndef __KERNEL__
> > > +extern int bpf_kfunc_multi_st_ops_test_1(struct st_ops_args *args, u32 id) __weak __ksym;
> > > +extern int bpf_kfunc_multi_st_ops_test_1_assoc(struct st_ops_args *args) __weak __ksym;
> > > +#endif
> > 
> > Nit: wbpf_kfunc_multi_st_ops_test_1 change is not necessary, right?
> 
> Right, but it felt wrong to only change one of these decls.
> 
> This header is weird in that it is included both in the module code
> and in BPF progs, although it is typically not a problem since the
> most kfunc signatures match.

I think it is used this way, so that compiler can warn user about
signature mismatch during development.

> Maybe it should have #ifndef __KERNEL__ followed by kfunc declarations
> that correspond to vmlinux.h format? I haven't tried that, but seems
> logical to me.