[PATCH] libbpf: optimize the redundant code in the bpf_object__init_user_btf_maps() function.

[PATCH] libbpf: optimize the redundant code in the bpf_object__init_user_btf_maps() function.

[Jianyun Gao]

In the elf_sec_data() function, the input parameter 'scn' will be
evaluated. If it is NULL, then it will directly return NULL. Therefore,
the return value of the elf_sec_data() function already takes into
account the case where the input parameter scn is NULL. Therefore,
subsequently, the code only needs to check whether the return value of
the elf_sec_data() function is NULL.

Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
---
 tools/lib/bpf/libbpf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b90574f39d1c..9e66104a61eb 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2988,15 +2988,15 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
 	int nr_types, i, vlen, err;
 	const struct btf_type *t;
 	const char *name;
-	Elf_Data *data;
+	Elf_Data *scn_data;
 	Elf_Scn *scn;
 
 	if (obj->efile.btf_maps_shndx < 0)
 		return 0;
 
 	scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
-	data = elf_sec_data(obj, scn);
-	if (!scn || !data) {
+	scn_data = elf_sec_data(obj, scn);
+	if (!scn_data) {
 		pr_warn("elf: failed to get %s map definitions for %s\n",
 			MAPS_ELF_SEC, obj->path);
 		return -EINVAL;
-- 
2.34.1

Re: [PATCH] libbpf: optimize the redundant code in the bpf_object__init_user_btf_maps() function.

[Jiri Olsa]

On Fri, Oct 24, 2025 at 02:07:20PM +0800, Jianyun Gao wrote:
> In the elf_sec_data() function, the input parameter 'scn' will be
> evaluated. If it is NULL, then it will directly return NULL. Therefore,
> the return value of the elf_sec_data() function already takes into
> account the case where the input parameter scn is NULL. Therefore,
> subsequently, the code only needs to check whether the return value of
> the elf_sec_data() function is NULL.
> 
> Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
> ---
>  tools/lib/bpf/libbpf.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index b90574f39d1c..9e66104a61eb 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -2988,15 +2988,15 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
>  	int nr_types, i, vlen, err;
>  	const struct btf_type *t;
>  	const char *name;
> -	Elf_Data *data;
> +	Elf_Data *scn_data;

makes sense to me, but this rename breaks compilation later on

libbpf.c:3027:53: error: ‘data’ undeclared (first use in this function)

jirka

>  	Elf_Scn *scn;
>  
>  	if (obj->efile.btf_maps_shndx < 0)
>  		return 0;
>  
>  	scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
> -	data = elf_sec_data(obj, scn);
> -	if (!scn || !data) {
> +	scn_data = elf_sec_data(obj, scn);
> +	if (!scn_data) {
>  		pr_warn("elf: failed to get %s map definitions for %s\n",
>  			MAPS_ELF_SEC, obj->path);
>  		return -EINVAL;
> -- 
> 2.34.1
> 

Re: [PATCH] libbpf: optimize the redundant code in the bpf_object__init_user_btf_maps() function.

[Jianyun Gao]

Hi Jiri, thank you for your review. And I have realized my mistake in
this patch. I will fix it in the next patch!

On Fri, Oct 24, 2025 at 2:57 PM Jiri Olsa <olsajiri@gmail.com> wrote:
>
> On Fri, Oct 24, 2025 at 02:07:20PM +0800, Jianyun Gao wrote:
> > In the elf_sec_data() function, the input parameter 'scn' will be
> > evaluated. If it is NULL, then it will directly return NULL. Therefore,
> > the return value of the elf_sec_data() function already takes into
> > account the case where the input parameter scn is NULL. Therefore,
> > subsequently, the code only needs to check whether the return value of
> > the elf_sec_data() function is NULL.
> >
> > Signed-off-by: Jianyun Gao <jianyungao89@gmail.com>
> > ---
> >  tools/lib/bpf/libbpf.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index b90574f39d1c..9e66104a61eb 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -2988,15 +2988,15 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
> >       int nr_types, i, vlen, err;
> >       const struct btf_type *t;
> >       const char *name;
> > -     Elf_Data *data;
> > +     Elf_Data *scn_data;
>
> makes sense to me, but this rename breaks compilation later on
>
> libbpf.c:3027:53: error: ‘data’ undeclared (first use in this function)
>
> jirka
>
> >       Elf_Scn *scn;
> >
> >       if (obj->efile.btf_maps_shndx < 0)
> >               return 0;
> >
> >       scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
> > -     data = elf_sec_data(obj, scn);
> > -     if (!scn || !data) {
> > +     scn_data = elf_sec_data(obj, scn);
> > +     if (!scn_data) {
> >               pr_warn("elf: failed to get %s map definitions for %s\n",
> >                       MAPS_ELF_SEC, obj->path);
> >               return -EINVAL;
> > --
> > 2.34.1
> >