Re: [PATCH bpf-next v2 2/2] selftests/bpf: Test bpf_strcat,bpf_strncat kfuncs

[kernel test robot <lkp@intel.com>]

Hi Rong,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Rong-Tao/selftests-bpf-Test-bpf_strcat-bpf_strncat-kfuncs/20260807-065842
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/tencent_DB0510330C3A8574B3C62E6154165FCB4709%40qq.com
patch subject: [PATCH bpf-next v2 2/2] selftests/bpf: Test bpf_strcat,bpf_strncat kfuncs
config: riscv-randconfig-r131-20260807 (https://download.01.org/0day-ci/archive/20260808/202608081054.Y56a5ufe-lkp@intel.com/config)
compiler: riscv64-linux-gcc (GCC) 8.5.0
sparse: v0.6.5-rc1
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260808/202608081054.Y56a5ufe-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202608081054.Y56a5ufe-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from include/uapi/linux/filter.h:9,
                    from include/linux/bpf.h:8,
                    from kernel/bpf/helpers.c:4:
   kernel/bpf/helpers.c: In function '__bpf_strncat':
>> include/linux/compiler_types.h:702:38: error: call to '__compiletime_assert_851' declared with attribute error: min(slen, sz) signedness error
     _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
                                         ^
   include/linux/compiler.h:68:3: note: in definition of macro '__trace_if_value'
     (cond) ?     \
      ^~~~
   include/linux/compiler.h:55:28: note: in expansion of macro '__trace_if_var'
    #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
                               ^~~~~~~~~~~~~~
   kernel/bpf/helpers.c:4219:2: note: in expansion of macro 'if'
     if (space <= 1 || space < min(slen, sz) + 1)
     ^~
   include/linux/compiler_types.h:690:2: note: in expansion of macro '__compiletime_assert'
     __compiletime_assert(condition, msg, prefix, suffix)
     ^~~~~~~~~~~~~~~~~~~~
   include/linux/compiler_types.h:702:2: note: in expansion of macro '_compiletime_assert'
     _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
     ^~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:40:37: note: in expansion of macro 'compiletime_assert'
    #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                        ^~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:93:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
     BUILD_BUG_ON_MSG(!__types_ok(ux, uy),  \
     ^~~~~~~~~~~~~~~~
   include/linux/minmax.h:98:2: note: in expansion of macro '__careful_cmp_once'
     __careful_cmp_once(op, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
     ^~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:105:19: note: in expansion of macro '__careful_cmp'
    #define min(x, y) __careful_cmp(min, x, y)
                      ^~~~~~~~~~~~~
   kernel/bpf/helpers.c:4219:28: note: in expansion of macro 'min'
     if (space <= 1 || space < min(slen, sz) + 1)
                               ^~~


vim +/__compiletime_assert_851 +702 include/linux/compiler_types.h

eb5c2d4b45e3d2 Will Deacon 2020-07-21  688  
eb5c2d4b45e3d2 Will Deacon 2020-07-21  689  #define _compiletime_assert(condition, msg, prefix, suffix) \
eb5c2d4b45e3d2 Will Deacon 2020-07-21  690  	__compiletime_assert(condition, msg, prefix, suffix)
eb5c2d4b45e3d2 Will Deacon 2020-07-21  691  
eb5c2d4b45e3d2 Will Deacon 2020-07-21  692  /**
eb5c2d4b45e3d2 Will Deacon 2020-07-21  693   * compiletime_assert - break build and emit msg if condition is false
eb5c2d4b45e3d2 Will Deacon 2020-07-21  694   * @condition: a compile-time constant condition to check
eb5c2d4b45e3d2 Will Deacon 2020-07-21  695   * @msg:       a message to emit if condition is false
eb5c2d4b45e3d2 Will Deacon 2020-07-21  696   *
eb5c2d4b45e3d2 Will Deacon 2020-07-21  697   * In tradition of POSIX assert, this macro will break the build if the
eb5c2d4b45e3d2 Will Deacon 2020-07-21  698   * supplied condition is *false*, emitting the supplied error message if the
eb5c2d4b45e3d2 Will Deacon 2020-07-21  699   * compiler has support to do so.
eb5c2d4b45e3d2 Will Deacon 2020-07-21  700   */
eb5c2d4b45e3d2 Will Deacon 2020-07-21  701  #define compiletime_assert(condition, msg) \
eb5c2d4b45e3d2 Will Deacon 2020-07-21 @702  	_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
eb5c2d4b45e3d2 Will Deacon 2020-07-21  703  

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