Re: [PATCH v8 3/4] scanf: convert self-test to KUnit

[Petr Mladek]

On Sat 2025-02-15 14:52:22, Tamir Duberstein wrote:
> On Sat, Feb 15, 2025 at 1:51 PM kernel test robot <lkp@xxxxxxxxx> wrote:
> >
> > Hi Tamir,
> >
> > kernel test robot noticed the following build warnings:
> >
> > [auto build test WARNING on 7b7a883c7f4de1ee5040bd1c32aabaafde54d209]
> >
> > url:
> https://github.com/intel-lab-lkp/linux/commits/Tamir-Duberstein/scanf-implicate-test-line-in-failure-messages/20250215-002302
> > base:   7b7a883c7f4de1ee5040bd1c32aabaafde54d209
> > patch link:
> https://lore.kernel.org/r/20250214-scanf-kunit-convert-v8-3-5ea50f95f83c%40gmail.com
> > patch subject: [PATCH v8 3/4] scanf: convert self-test to KUnit
> > config: sh-randconfig-002-20250216 (
> https://download.01.org/0day-ci/archive/20250216/202502160245.KUrryBJR-lkp@xxxxxxxxx/config
> )
> > compiler: sh4-linux-gcc (GCC) 14.2.0
> > reproduce (this is a W=1 build): (
> https://download.01.org/0day-ci/archive/20250216/202502160245.KUrryBJR-lkp@xxxxxxxxx/reproduce
> )
> >
> > If you fix the issue in a separate patch/commit (i.e. not just a new
> version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > | Closes:
> https://lore.kernel.org/oe-kbuild-all/202502160245.KUrryBJR-lkp@xxxxxxxxx/
> >
> > All warnings (new ones prefixed by >>):
> >
> >    In file included from <command-line>:
> >    lib/tests/scanf_kunit.c: In function 'numbers_list_ll':
> > >> include/linux/compiler.h:197:61: warning: function 'numbers_list_ll'
> might be a candidate for 'gnu_scanf' format attribute
> [-Wsuggest-attribute=format]
> 
> I am not able to reproduce these warnings with clang 19.1.7. They also
> don't obviously make sense to me.

I have reproduced the problem with gcc:

$> gcc --version
gcc (SUSE Linux) 14.2.1 20250220 [revision 9ffecde121af883b60bbe60d00425036bc873048]

$> make W=1 lib/test_scanf.ko
  CALL    scripts/checksyscalls.sh
  DESCEND objtool
  INSTALL libsubcmd_headers
  CC [M]  lib/test_scanf.o
In file included from <command-line>:
lib/test_scanf.c: In function ‘numbers_list_ll’:
./include/linux/compiler.h:197:61: warning: function ‘numbers_list_ll’ might be a candidate for ‘gnu_scanf’ format attribute [-Wsuggest-attribute=format]
  197 | #define __BUILD_BUG_ON_ZERO_MSG(e, msg) ((int)sizeof(struct {_Static_assert(!(e), msg);}))
      |                                                             ^
[...]

It seems that it is a regression introduced by the first
patch of this patch set. And the fix is:

diff --git a/lib/test_scanf.c b/lib/test_scanf.c
index d1664e0d0138..e65b10c3dc11 100644
--- a/lib/test_scanf.c
+++ b/lib/test_scanf.c
@@ -27,7 +27,7 @@ static struct rnd_state rnd_state __initdata;
 typedef int (*check_fn)(const char *file, const int line, const void *check_data,
 			const char *string, const char *fmt, int n_args, va_list ap);
 
-static void __scanf(6, 0) __init
+static void __scanf(6, 8) __init
 _test(const char *file, const int line, check_fn fn, const void *check_data, const char *string,
 	const char *fmt, int n_args, ...)
 {

Best Regards,
Petr