[PATCH] libbpf: fix returnvar.cocci warnings

[PATCH] libbpf: fix returnvar.cocci warnings

[kernel test robot]

From: kernel test robot <lkp@intel.com>

tools/lib/bpf/relo_core.c:1064:8-11: Unneeded variable: "len". Return "0" on line 1086


 Remove unneeded variable used to store return value.

Generated by: scripts/coccinelle/misc/returnvar.cocci

Fixes: b58af63aab11 ("libbpf: Refactor CO-RE relo human description formatting routine")
CC: Andrii Nakryiko <andrii@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: kernel test robot <lkp@intel.com>
---

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   f02ac5c95dfd45d2f50ecc68d79177de326c668c
commit: b58af63aab11e4ae00fe96de9505759cfdde8ee9 [6746/7265] libbpf: Refactor CO-RE relo human description formatting routine
:::::: branch date: 2 hours ago
:::::: commit date: 9 hours ago

 tools/lib/bpf/relo_core.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/tools/lib/bpf/relo_core.c
+++ b/tools/lib/bpf/relo_core.c
@@ -1061,7 +1061,7 @@ static int bpf_core_format_spec(char *bu
 	const struct btf_enum *e;
 	const char *s;
 	__u32 type_id;
-	int i, len = 0;
+	int i;
 
 #define append_buf(fmt, args...)				\
 	({							\
@@ -1083,7 +1083,7 @@ static int bpf_core_format_spec(char *bu
 		   type_id, btf_kind_str(t), str_is_empty(s) ? "<anon>" : s);
 
 	if (core_relo_is_type_based(spec->relo_kind))
-		return len;
+		return 0;
 
 	if (core_relo_is_enumval_based(spec->relo_kind)) {
 		t = skip_mods_and_typedefs(spec->btf, type_id, NULL);
@@ -1091,7 +1091,7 @@ static int bpf_core_format_spec(char *bu
 		s = btf__name_by_offset(spec->btf, e->name_off);
 
 		append_buf("::%s = %u", s, e->val);
-		return len;
+		return 0;
 	}
 
 	if (core_relo_is_field_based(spec->relo_kind)) {
@@ -1110,10 +1110,10 @@ static int bpf_core_format_spec(char *bu
 			append_buf(" @ offset %u.%u)", spec->bit_offset / 8, spec->bit_offset % 8);
 		else
 			append_buf(" @ offset %u)", spec->bit_offset / 8);
-		return len;
+		return 0;
 	}
 
-	return len;
+	return 0;
 #undef append_buf
 }
 

[linux-next:master 6746/7265] tools/lib/bpf/relo_core.c:1064:8-11: Unneeded variable: "len". Return "0" on line 1086

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   f02ac5c95dfd45d2f50ecc68d79177de326c668c
commit: b58af63aab11e4ae00fe96de9505759cfdde8ee9 [6746/7265] libbpf: Refactor CO-RE relo human description formatting routine
config: sparc-randconfig-c023-20220425 (https://download.01.org/0day-ci/archive/20220427/202204271656.OTIj2QNJ-lkp@intel.com/config)
compiler: sparc64-linux-gcc (GCC) 11.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>


cocci warnings: (new ones prefixed by >>)
>> tools/lib/bpf/relo_core.c:1064:8-11: Unneeded variable: "len". Return "0" on line 1086

Please review and possibly fold the followup patch.

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH] libbpf: fix returnvar.cocci warnings

[Alexei Starovoitov]

On Wed, Apr 27, 2022 at 1:04 AM kernel test robot <lkp@intel.com> wrote:
>
> From: kernel test robot <lkp@intel.com>
>
> tools/lib/bpf/relo_core.c:1064:8-11: Unneeded variable: "len". Return "0" on line 1086
>
>
>  Remove unneeded variable used to store return value.
>
> Generated by: scripts/coccinelle/misc/returnvar.cocci
>
> Fixes: b58af63aab11 ("libbpf: Refactor CO-RE relo human description formatting routine")
> CC: Andrii Nakryiko <andrii@kernel.org>
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: kernel test robot <lkp@intel.com>
> ---
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   f02ac5c95dfd45d2f50ecc68d79177de326c668c
> commit: b58af63aab11e4ae00fe96de9505759cfdde8ee9 [6746/7265] libbpf: Refactor CO-RE relo human description formatting routine
> :::::: branch date: 2 hours ago
> :::::: commit date: 9 hours ago
>
>  tools/lib/bpf/relo_core.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> --- a/tools/lib/bpf/relo_core.c
> +++ b/tools/lib/bpf/relo_core.c
> @@ -1061,7 +1061,7 @@ static int bpf_core_format_spec(char *bu
>         const struct btf_enum *e;
>         const char *s;
>         __u32 type_id;
> -       int i, len = 0;
> +       int i;
>
>  #define append_buf(fmt, args...)                               \
>         ({                                                      \
> @@ -1083,7 +1083,7 @@ static int bpf_core_format_spec(char *bu
>                    type_id, btf_kind_str(t), str_is_empty(s) ? "<anon>" : s);
>
>         if (core_relo_is_type_based(spec->relo_kind))
> -               return len;
> +               return 0;

cocci is wrong.
It missed append_buf() macro.

Please fix cocci so we don't have to manually deal with
broken patches like this one.

Re: [PATCH] libbpf: fix returnvar.cocci warnings

[Andrii Nakryiko]

On Wed, Apr 27, 2022 at 9:07 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Wed, Apr 27, 2022 at 1:04 AM kernel test robot <lkp@intel.com> wrote:
> >
> > From: kernel test robot <lkp@intel.com>
> >
> > tools/lib/bpf/relo_core.c:1064:8-11: Unneeded variable: "len". Return "0" on line 1086
> >
> >
> >  Remove unneeded variable used to store return value.
> >
> > Generated by: scripts/coccinelle/misc/returnvar.cocci
> >
> > Fixes: b58af63aab11 ("libbpf: Refactor CO-RE relo human description formatting routine")
> > CC: Andrii Nakryiko <andrii@kernel.org>
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: kernel test robot <lkp@intel.com>
> > ---
> >
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > head:   f02ac5c95dfd45d2f50ecc68d79177de326c668c
> > commit: b58af63aab11e4ae00fe96de9505759cfdde8ee9 [6746/7265] libbpf: Refactor CO-RE relo human description formatting routine
> > :::::: branch date: 2 hours ago
> > :::::: commit date: 9 hours ago
> >
> >  tools/lib/bpf/relo_core.c |   10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > --- a/tools/lib/bpf/relo_core.c
> > +++ b/tools/lib/bpf/relo_core.c
> > @@ -1061,7 +1061,7 @@ static int bpf_core_format_spec(char *bu
> >         const struct btf_enum *e;
> >         const char *s;
> >         __u32 type_id;
> > -       int i, len = 0;
> > +       int i;
> >
> >  #define append_buf(fmt, args...)                               \
> >         ({                                                      \
> > @@ -1083,7 +1083,7 @@ static int bpf_core_format_spec(char *bu
> >                    type_id, btf_kind_str(t), str_is_empty(s) ? "<anon>" : s);
> >
> >         if (core_relo_is_type_based(spec->relo_kind))
> > -               return len;
> > +               return 0;
>
> cocci is wrong.
> It missed append_buf() macro.

Should be irrelevant once [0] lands. It makes use of that return value directly.

  [0] https://patchwork.kernel.org/project/netdevbpf/patch/20220428041523.4089853-2-andrii@kernel.org/

>
> Please fix cocci so we don't have to manually deal with
> broken patches like this one.