linux-kernel - [bvanassche:tracing 2/2] include/linux/compiler.h:246:47: warning: ordered comparison of pointer with null pointer

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Message-ID: <202208250433.EVz5pZkB-lkp@intel.com>
Date:   Thu, 25 Aug 2022 04:50:28 +0800
From:   kernel test robot <lkp@...el.com>
To:     Bart Van Assche <bvanassche@....org>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org
Subject: [bvanassche:tracing 2/2] include/linux/compiler.h:246:47: warning:
 ordered comparison of pointer with null pointer

tree:   https://github.com/bvanassche/linux tracing
head:   e50691460d5ea5a49b903e0ea50276e942b6f34f
commit: e50691460d5ea5a49b903e0ea50276e942b6f34f [2/2] tracing: Define is_signed_type() once
config: sh-allmodconfig (https://download.01.org/0day-ci/archive/20220825/202208250433.EVz5pZkB-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/bvanassche/linux/commit/e50691460d5ea5a49b903e0ea50276e942b6f34f
        git remote add bvanassche https://github.com/bvanassche/linux
        git fetch --no-tags bvanassche tracing
        git checkout e50691460d5ea5a49b903e0ea50276e942b6f34f
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sh SHELL=/bin/bash drivers/net/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

   In file included from include/trace/define_trace.h:102,
                    from drivers/net/wireless/mediatek/mt7601u/trace.h:392,
                    from drivers/net/wireless/mediatek/mt7601u/trace.c:11:
>> include/linux/compiler.h:246:47: warning: ordered comparison of pointer with null pointer [-Wextra]
     246 | #define is_signed_type(type)    (((type)(-1)) <= (type)0)
         |                                               ^~
   include/trace/trace_events.h:244:9: note: in definition of macro 'DECLARE_EVENT_CLASS'
     244 |         tstruct                                                         \
         |         ^~~~~~~
   include/trace/trace_events.h:43:30: note: in expansion of macro 'PARAMS'
      43 |                              PARAMS(tstruct),                  \
         |                              ^~~~~~
   drivers/net/wireless/mediatek/mt7601u/./trace.h:98:1: note: in expansion of macro 'TRACE_EVENT'
      98 | TRACE_EVENT(mt_vend_req,
         | ^~~~~~~~~~~
   drivers/net/wireless/mediatek/mt7601u/./trace.h:102:9: note: in expansion of macro 'TP_STRUCT__entry'
     102 |         TP_STRUCT__entry(
         |         ^~~~~~~~~~~~~~~~
   include/trace/stages/stage4_event_fields.h:11:22: note: in expansion of macro 'is_signed_type'
      11 |         .is_signed = is_signed_type(_type), .filter_type = _filter_type },
         |                      ^~~~~~~~~~~~~~
   include/trace/stages/stage4_event_fields.h:20:33: note: in expansion of macro '__field_ext'
      20 | #define __field(type, item)     __field_ext(type, item, FILTER_OTHER)
         |                                 ^~~~~~~~~~~
   drivers/net/wireless/mediatek/mt7601u/./trace.h:105:56: note: in expansion of macro '__field'
     105 |                 __field(u16, val) __field(u16, offset) __field(void*, buf)
         |                                                        ^~~~~~~


vim +246 include/linux/compiler.h

   241	
   242	/*
   243	 * Whether 'type' is a signed type or an unsigned type. Supports scalar types,
   244	 * bool and also pointer types.
   245	 */
 > 246	#define is_signed_type(type)	(((type)(-1)) <= (type)0)
   247	

-- 
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https://01.org/lkp