[kbuild-all] [vincent.guittot:sched/pelt 1/2] include/linux/kernel.h:851:29: warning: comparison of distinct pointer types lacks a cast

tree: https://git.linaro.org/people/vincent.guittot/kernel.git sched/pelt head: cc807c0b8d03785da906a6a8436be5838bfe9d54 commit: a057128bc3087ebc9505454a1b5d7a4ae35c6e04 [1/2] sched/fair: handle case of task_h_load() returning 0 config: ia64-randconfig-r035-20200710 (attached as .config) compiler: ia64-linux-gcc (GCC) 9.3.0 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 git checkout a057128bc3087ebc9505454a1b5d7a4ae35c6e04 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=ia64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): In file included from include/linux/list.h:9, from include/linux/rculist.h:10, from include/linux/pid.h:5, from include/linux/sched.h:14, from kernel/sched/sched.h:5, from kernel/sched/fair.c:23: kernel/sched/fair.c: In function 'update_misfit_status': 851 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) | ^~ include/linux/kernel.h:865:4: note: in expansion of macro '__typecheck' 865 | (__typecheck(x, y) && __no_side_effects(x, y)) | ^~~~~~~~~~~ include/linux/kernel.h:875:24: note: in expansion of macro '__safe_cmp' 875 | __builtin_choose_expr(__safe_cmp(x, y), \ | ^~~~~~~~~~ include/linux/kernel.h:891:19: note: in expansion of macro '__careful_cmp' 891 | #define max(x, y) __careful_cmp(x, y, >) | ^~~~~~~~~~~~~ kernel/sched/fair.c:4056:25: note: in expansion of macro 'max' 4056 | rq->misfit_task_load = max(task_h_load(p), 1); | ^~~ kernel/sched/fair.c: In function 'detach_tasks': 851 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) | ^~ include/linux/kernel.h:865:4: note: in expansion of macro '__typecheck' 865 | (__typecheck(x, y) && __no_side_effects(x, y)) | ^~~~~~~~~~~ include/linux/kernel.h:875:24: note: in expansion of macro '__safe_cmp' 875 | __builtin_choose_expr(__safe_cmp(x, y), \ | ^~~~~~~~~~ include/linux/kernel.h:891:19: note: in expansion of macro '__careful_cmp' 891 | #define max(x, y) __careful_cmp(x, y, >) | ^~~~~~~~~~~~~ kernel/sched/fair.c:7662:11: note: in expansion of macro 'max' 7662 | load = max(task_h_load(p), 1); | ^~~ vim +851 include/linux/kernel.h 526211bc58c4b32 Ingo Molnar 2009-03-05 837 ^1da177e4c3f415 Linus Torvalds 2005-04-16 838 /* 3c8ba0d61d04ced Kees Cook 2018-03-30 839 * min()/max()/clamp() macros must accomplish three things: 3c8ba0d61d04ced Kees Cook 2018-03-30 840 * 3c8ba0d61d04ced Kees Cook 2018-03-30 841 * - avoid multiple evaluations of the arguments (so side-effects like 3c8ba0d61d04ced Kees Cook 2018-03-30 842 * "x++" happen only once) when non-constant. 3c8ba0d61d04ced Kees Cook 2018-03-30 843 * - perform strict type-checking (to generate warnings instead of 3c8ba0d61d04ced Kees Cook 2018-03-30 844 * nasty runtime surprises). See the "unnecessary" pointer comparison 3c8ba0d61d04ced Kees Cook 2018-03-30 845 * in __typecheck(). 3c8ba0d61d04ced Kees Cook 2018-03-30 846 * - retain result as a constant expressions when called with only 3c8ba0d61d04ced Kees Cook 2018-03-30 847 * constant expressions (to avoid tripping VLA warnings in stack 3c8ba0d61d04ced Kees Cook 2018-03-30 848 * allocation usage). 3c8ba0d61d04ced Kees Cook 2018-03-30 849 */ 3c8ba0d61d04ced Kees Cook 2018-03-30 850 #define __typecheck(x, y) \ 3c8ba0d61d04ced Kees Cook 2018-03-30 @851 (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) 3c8ba0d61d04ced Kees Cook 2018-03-30 852 :::::: The code at line 851 was first introduced by commit :::::: 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 kernel.h: Retain constant expression output for max()/min() :::::: TO: Kees Cook <keescook(a)chromium.org&gt; :::::: CC: Linus Torvalds <torvalds(a)linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org