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Date: Tue, 11 Jun 2024 09:54:14 -0600
From: Daniel Xu <dxu@dxuuu.xyz>
To: Jiri Olsa <olsajiri@gmail.com>
Cc: shuah@kernel.org, ast@kernel.org, andrii@kernel.org, eddyz87@gmail.com, 
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Subject: Re: [PATCH bpf-next v4 06/12] bpf: selftests: Fix
 bpf_session_cookie() kfunc prototype
Message-ID: <chydnuotqnmamlfmgzgnwurj5flaegp2bjebxldqwc2y2ngs5x@3h4blknbqhlw>
References: <cover.1717881178.git.dxu@dxuuu.xyz>
 <34708481d71ea72c23a78a5209e04a76b261a01d.1717881178.git.dxu@dxuuu.xyz>
 <Zmb52Qp__CBzbgDh@krava>
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In-Reply-To: <Zmb52Qp__CBzbgDh@krava>

Hi Jiri,

On Mon, Jun 10, 2024 at 03:04:25PM GMT, Jiri Olsa wrote:
> On Sat, Jun 08, 2024 at 03:16:02PM -0600, Daniel Xu wrote:
> > The prototype defined in bpf_kfuncs.h was not in line with how the
> > actual kfunc was defined. This causes compilation errors when kfunc
> > prototypes are generated from BTF.
> > 
> > Fix by aligning with actual kfunc definition.
> > 
> > Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
> > ---
> >  tools/testing/selftests/bpf/bpf_kfuncs.h                        | 2 +-
> >  tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/bpf/bpf_kfuncs.h b/tools/testing/selftests/bpf/bpf_kfuncs.h
> > index be91a6919315..3b6675ab4086 100644
> > --- a/tools/testing/selftests/bpf/bpf_kfuncs.h
> > +++ b/tools/testing/selftests/bpf/bpf_kfuncs.h
> > @@ -77,5 +77,5 @@ extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,
> >  				      struct bpf_key *trusted_keyring) __ksym;
> >  
> >  extern bool bpf_session_is_return(void) __ksym __weak;
> > -extern long *bpf_session_cookie(void) __ksym __weak;
> > +extern __u64 *bpf_session_cookie(void) __ksym __weak;
> 
> the original intent was to expose long instead of __u64 :-\
> 
> could we rather change the bpf_session_cookie function to return long?
> should be just return value type change

Sounds reasonable to me. I don't think the kfunc has made it to a
release yet, so perhaps if we extract this commit out as a fix to bpf
tree it can still make it into 6.10. That way we won't have to worry
about any ABI changes.

Thanks,
Daniel