linux-kernel - Re: [PATCH bpf-next v10 11/13] libbpf: Add btf_is_sorted and btf_sorted_start

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Message-ID: <CAEf4BzYoyTfCX22kFUS2ymZPehQEbGeQztzGkAMuAL7d1bnUkw@mail.gmail.com>
Date: Fri, 19 Dec 2025 09:35:16 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Donglin Peng <dolinux.peng@...il.com>
Cc: ast@...nel.org, eddyz87@...il.com, zhangxiaoqin@...omi.com, 
	ihor.solodrai@...ux.dev, linux-kernel@...r.kernel.org, bpf@...r.kernel.org, 
	pengdonglin <pengdonglin@...omi.com>, Alan Maguire <alan.maguire@...cle.com>
Subject: Re: [PATCH bpf-next v10 11/13] libbpf: Add btf_is_sorted and
 btf_sorted_start_id helpers to refactor the code

On Thu, Dec 18, 2025 at 9:51 PM Donglin Peng <dolinux.peng@...il.com> wrote:
>
> On Fri, Dec 19, 2025 at 8:05 AM Andrii Nakryiko
> <andrii.nakryiko@...il.com> wrote:
> >
> > On Thu, Dec 18, 2025 at 3:31 AM Donglin Peng <dolinux.peng@...il.com> wrote:
> > >
> > > From: pengdonglin <pengdonglin@...omi.com>
> > >
> > > Introduce two new helper functions to clarify the code and no
> > > functional changes are introduced.
> > >
> > > Cc: Eduard Zingerman <eddyz87@...il.com>
> > > Cc: Alexei Starovoitov <ast@...nel.org>
> > > Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
> > > Cc: Alan Maguire <alan.maguire@...cle.com>
> > > Cc: Ihor Solodrai <ihor.solodrai@...ux.dev>
> > > Cc: Xiaoqin Zhang <zhangxiaoqin@...omi.com>
> > > Signed-off-by: pengdonglin <pengdonglin@...omi.com>
> > > ---
> > >  tools/lib/bpf/btf.c             | 14 ++++++++++++--
> > >  tools/lib/bpf/libbpf_internal.h |  2 ++
> > >  2 files changed, 14 insertions(+), 2 deletions(-)
> > >
> >
> > It just adds more functions to jump to and check what it's doing. I
> > don't think this adds much value, just drop this patch
>
> Could adding the __always_inline be acceptable?

No! This is not a performance concern, just mental overhead when
reading the code.

>
> >
> >
> > > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> > > index b5b0898d033d..571b72bd90b5 100644
> > > --- a/tools/lib/bpf/btf.c
> > > +++ b/tools/lib/bpf/btf.c
> > > @@ -626,6 +626,16 @@ const struct btf *btf__base_btf(const struct btf *btf)
> > >         return btf->base_btf;
> > >  }
> > >
> > > +int btf_sorted_start_id(const struct btf *btf)
> > > +{
> > > +       return btf->sorted_start_id;
> > > +}
> > > +
> > > +bool btf_is_sorted(const struct btf *btf)
> > > +{
> > > +       return btf->sorted_start_id > 0;
> > > +}
> > > +
> > >  /* internal helper returning non-const pointer to a type */
> > >  struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id)
> > >  {
> > > @@ -976,11 +986,11 @@ static __s32 btf_find_by_name_kind(const struct btf *btf, int start_id,
> > >         if (kind == BTF_KIND_UNKN || strcmp(type_name, "void") == 0)
> > >                 return 0;
> > >
> > > -       if (btf->sorted_start_id > 0 && type_name[0]) {
> > > +       if (btf_is_sorted(btf) && type_name[0]) {
> > >                 __s32 end_id = btf__type_cnt(btf) - 1;
> > >
> > >                 /* skip anonymous types */
> > > -               start_id = max(start_id, btf->sorted_start_id);
> > > +               start_id = max(start_id, btf_sorted_start_id(btf));
> > >                 idx = btf_find_by_name_bsearch(btf, type_name, start_id, end_id);
> > >                 if (unlikely(idx < 0))
> > >                         return libbpf_err(-ENOENT);
> > > diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
> > > index fc59b21b51b5..95e6848396b4 100644
> > > --- a/tools/lib/bpf/libbpf_internal.h
> > > +++ b/tools/lib/bpf/libbpf_internal.h
> > > @@ -250,6 +250,8 @@ const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, __u32 id, _
> > >  const struct btf_header *btf_header(const struct btf *btf);
> > >  void btf_set_base_btf(struct btf *btf, const struct btf *base_btf);
> > >  int btf_relocate(struct btf *btf, const struct btf *base_btf, __u32 **id_map);
> > > +int btf_sorted_start_id(const struct btf *btf);
> > > +bool btf_is_sorted(const struct btf *btf);
> > >
> > >  static inline enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
> > >  {
> > > --
> > > 2.34.1
> > >