Hi Changbin, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on linus/master] [also build test WARNING on v4.17 next-20180608] [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/changbin-du-intel-com/kernel-hacking-GCC-optimization-for-better-debug-experience-Og/20180606-001415 config: i386-randconfig-x079-06101602 (attached as .config) compiler: gcc-7 (Debian 7.3.0-16) 7.3.0 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/page_32.h:35:0, from arch/x86/include/asm/page.h:14, from arch/x86/include/asm/thread_info.h:12, from include/linux/thread_info.h:38, from arch/x86/include/asm/preempt.h:7, from include/linux/preempt.h:81, from include/linux/spinlock.h:51, from include/linux/seqlock.h:36, from include/linux/time.h:6, from include/linux/stat.h:19, from include/linux/module.h:10, from net//bluetooth/mgmt.c:27: net//bluetooth/mgmt.c: In function 'read_local_oob_ext_data_complete': >> include/linux/string.h:345:9: warning: 'r256' may be used uninitialized in this function [-Wmaybe-uninitialized] return __builtin_memcpy(p, q, size); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ net//bluetooth/mgmt.c:5669:27: note: 'r256' was declared here u8 *h192, *r192, *h256, *r256; ^~~~ -- In file included from arch/x86/include/asm/page_32.h:35:0, from arch/x86/include/asm/page.h:14, from arch/x86/include/asm/thread_info.h:12, from include/linux/thread_info.h:38, from arch/x86/include/asm/preempt.h:7, from include/linux/preempt.h:81, from include/linux/spinlock.h:51, from include/linux/seqlock.h:36, from include/linux/time.h:6, from include/linux/stat.h:19, from include/linux/module.h:10, from net/bluetooth/mgmt.c:27: net/bluetooth/mgmt.c: In function 'read_local_oob_ext_data_complete': >> include/linux/string.h:345:9: warning: 'r256' may be used uninitialized in this function [-Wmaybe-uninitialized] return __builtin_memcpy(p, q, size); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ net/bluetooth/mgmt.c:5669:27: note: 'r256' was declared here u8 *h192, *r192, *h256, *r256; ^~~~ vim +/r256 +345 include/linux/string.h 6974f0c4 Daniel Micay 2017-07-12 332 6974f0c4 Daniel Micay 2017-07-12 333 __FORTIFY_INLINE void *memcpy(void *p, const void *q, __kernel_size_t size) 6974f0c4 Daniel Micay 2017-07-12 334 { 6974f0c4 Daniel Micay 2017-07-12 335 size_t p_size = __builtin_object_size(p, 0); 6974f0c4 Daniel Micay 2017-07-12 336 size_t q_size = __builtin_object_size(q, 0); 6974f0c4 Daniel Micay 2017-07-12 337 if (__builtin_constant_p(size)) { 6974f0c4 Daniel Micay 2017-07-12 338 if (p_size < size) 6974f0c4 Daniel Micay 2017-07-12 339 __write_overflow(); 6974f0c4 Daniel Micay 2017-07-12 340 if (q_size < size) 6974f0c4 Daniel Micay 2017-07-12 341 __read_overflow2(); 6974f0c4 Daniel Micay 2017-07-12 342 } 6974f0c4 Daniel Micay 2017-07-12 343 if (p_size < size || q_size < size) 6974f0c4 Daniel Micay 2017-07-12 344 fortify_panic(__func__); 6974f0c4 Daniel Micay 2017-07-12 @345 return __builtin_memcpy(p, q, size); 6974f0c4 Daniel Micay 2017-07-12 346 } 6974f0c4 Daniel Micay 2017-07-12 347 :::::: The code at line 345 was first introduced by commit :::::: 6974f0c4555e285ab217cee58b6e874f776ff409 include/linux/string.h: add the option of fortified string.h functions :::::: TO: Daniel Micay <danielmicay@xxxxxxxxx> :::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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