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

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Message-ID: <772e728b89205fe2a6c70cefe6d594c2a8eabc83.camel@gmail.com>
Date: Tue, 20 Jan 2026 10:24:04 -0800
From: Eduard Zingerman <eddyz87@...il.com>
To: Ihor Solodrai <ihor.solodrai@...ux.dev>, Alexei Starovoitov
 <ast@...nel.org>,  Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko
 <andrii@...nel.org>, Martin KaFai Lau <martin.lau@...ux.dev>
Cc: Mykyta Yatsenko <yatsenko@...a.com>, Tejun Heo <tj@...nel.org>, Alan
 Maguire <alan.maguire@...cle.com>, Benjamin Tissoires <bentiss@...nel.org>,
 Jiri Kosina	 <jikos@...nel.org>, Amery Hung <ameryhung@...il.com>,
 bpf@...r.kernel.org, 	linux-kernel@...r.kernel.org,
 linux-input@...r.kernel.org, 	sched-ext@...ts.linux.dev
Subject: Re: [PATCH bpf-next v2 11/13] selftests/bpf: Migrate
 struct_ops_assoc test to KF_IMPLICIT_ARGS

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.