Hi Yang, [auto build test WARNING on linus/master] [also build test WARNING on v4.12-rc6] [cannot apply to tip/x86/core next-20170622] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/root/x86-idle-add-halt-poll-for-halt-idle/20170623-061318 config: i386-randconfig-x016-06222129 (attached as .config) compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901 reproduce: # save the attached .config to linux build tree make ARCH=i386 Note: it may well be a FALSE warning. FWIW you are at least aware of it now. http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings All warnings (new ones prefixed by >>): In file included from arch/x86/include/asm/preempt.h:5:0, from include/linux/preempt.h:80, from include/linux/spinlock.h:50, from include/linux/mmzone.h:7, from include/linux/gfp.h:5, from include/linux/mm.h:9, from arch/x86/kernel/process.c:5: arch/x86/kernel/process.c: In function 'check_poll': >> arch/x86/include/asm/percpu.h:109:3: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized] asm(op "l %1,"__percpu_arg(0) \ ^~~ arch/x86/kernel/process.c:351:15: note: 'val' was declared here unsigned int val, poll_duration; ^~~ -- In file included from arch/x86/include/asm/preempt.h:5:0, from include/linux/preempt.h:80, from include/linux/spinlock.h:50, from include/linux/mmzone.h:7, from include/linux/gfp.h:5, from include/linux/mm.h:9, from arch/x86//kernel/process.c:5: arch/x86//kernel/process.c: In function 'check_poll': >> arch/x86/include/asm/percpu.h:109:3: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized] asm(op "l %1,"__percpu_arg(0) \ ^~~ arch/x86//kernel/process.c:351:15: note: 'val' was declared here unsigned int val, poll_duration; ^~~ vim +/val +109 arch/x86/include/asm/percpu.h 0f5e4816 arch/x86/include/asm/percpu.h Tejun Heo 2009-10-29 93 pto_T__ pto_tmp__; \ 0f5e4816 arch/x86/include/asm/percpu.h Tejun Heo 2009-10-29 94 pto_tmp__ = (val); \ 23b764d0 arch/x86/include/asm/percpu.h Andi Kleen 2010-06-10 95 (void)pto_tmp__; \ bc9e3be2 include/asm-x86/percpu.h Joe Perches 2008-03-23 96 } \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 97 switch (sizeof(var)) { \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 98 case 1: \ 87b26406 arch/x86/include/asm/percpu.h Brian Gerst 2009-01-19 99 asm(op "b %1,"__percpu_arg(0) \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 100 : "+m" (var) \ 0f5e4816 arch/x86/include/asm/percpu.h Tejun Heo 2009-10-29 101 : "qi" ((pto_T__)(val))); \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 102 break; \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 103 case 2: \ 87b26406 arch/x86/include/asm/percpu.h Brian Gerst 2009-01-19 104 asm(op "w %1,"__percpu_arg(0) \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 105 : "+m" (var) \ 0f5e4816 arch/x86/include/asm/percpu.h Tejun Heo 2009-10-29 106 : "ri" ((pto_T__)(val))); \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 107 break; \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 108 case 4: \ 87b26406 arch/x86/include/asm/percpu.h Brian Gerst 2009-01-19 @109 asm(op "l %1,"__percpu_arg(0) \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 110 : "+m" (var) \ 0f5e4816 arch/x86/include/asm/percpu.h Tejun Heo 2009-10-29 111 : "ri" ((pto_T__)(val))); \ 3334052a include/asm-x86/percpu.h travis@xxxxxxx 2008-01-30 112 break; \ 9939ddaf arch/x86/include/asm/percpu.h Tejun Heo 2009-01-13 113 case 8: \ 87b26406 arch/x86/include/asm/percpu.h Brian Gerst 2009-01-19 114 asm(op "q %1,"__percpu_arg(0) \ 9939ddaf arch/x86/include/asm/percpu.h Tejun Heo 2009-01-13 115 : "+m" (var) \ 0f5e4816 arch/x86/include/asm/percpu.h Tejun Heo 2009-10-29 116 : "re" ((pto_T__)(val))); \ 9939ddaf arch/x86/include/asm/percpu.h Tejun Heo 2009-01-13 117 break; \ :::::: The code at line 109 was first introduced by commit :::::: 87b264065880fa696c121dad8498a60524e0f6de x86-64: Use absolute displacements for per-cpu accesses. :::::: TO: Brian Gerst <brgerst@xxxxxxxxx> :::::: CC: Tejun Heo <tj@xxxxxxxxxx> --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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