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-rc4 next-20180510] [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/20180509-213955 config: x86_64-randconfig-s1-05100951 (attached as .config) compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026 reproduce: # save the attached .config to linux build tree make ARCH=x86_64 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 >>): lib/test_firmware.c: In function 'trigger_batched_requests_async_store': >> lib/test_firmware.c:779:31: warning: 'rc' may be used uninitialized in this function [-Wmaybe-uninitialized] test_fw_config->test_result = rc; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~ -- kernel/futex.c: In function 'futex_atomic_op_inuser': >> kernel/futex.c:1604:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized] return oldval > cmparg; ~~~~~~~^~~~~~~~ -- kernel/kexec_file.c: In function 'kexec_apply_relocations': >> kernel/kexec_file.c:896:6: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized] if (ret) ^ -- mm/swap_state.c: In function '__add_to_swap_cache': >> mm/swap_state.c:156:9: warning: 'error' may be used uninitialized in this function [-Wmaybe-uninitialized] return error; ^~~~~ -- mm/swapfile.c: In function 'setup_swap_map_and_extents': >> mm/swapfile.c:3061:10: warning: 'nr_extents' may be used uninitialized in this function [-Wmaybe-uninitialized] return nr_extents; ^~~~~~~~~~ -- mm/ksm.c: In function 'stable_node_dup': >> mm/ksm.c:1365:15: warning: 'found_rmap_hlist_len' may be used uninitialized in this function [-Wmaybe-uninitialized] if (!found || ~~~~~~~^~ dup->rmap_hlist_len > found_rmap_hlist_len) { ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- mm/huge_memory.c: In function 'do_huge_pmd_wp_page': >> mm/huge_memory.c:1318:15: warning: 'huge_gfp' may be used uninitialized in this function [-Wmaybe-uninitialized] if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm, ^~~~~~~~~~~~~~~~~~~~~ -- fs/splice.c: In function 'iter_file_splice_write': >> fs/splice.c:694:10: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized] ssize_t ret; ^~~ -- In file included from include/asm-generic/bug.h:5:0, from arch/x86/include/asm/bug.h:83, from include/linux/bug.h:5, from include/linux/mmdebug.h:5, from include/linux/gfp.h:5, from include/linux/slab.h:15, from ipc/sem.c:73: ipc/sem.c: In function 'find_alloc_undo': >> include/linux/compiler.h:215:31: warning: 'ulp' may be used uninitialized in this function [-Wmaybe-uninitialized] case 8: *(volatile __u64 *)p = *(__u64 *)res; break; ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~ ipc/sem.c:1843:24: note: 'ulp' was declared here struct sem_undo_list *ulp; ^~~ -- block/blk-merge.c: In function '__blk_recalc_rq_segments': >> block/blk-merge.c:284:21: warning: 'bbio' may be used uninitialized in this function [-Wmaybe-uninitialized] if (seg_size > bbio->bi_seg_back_size) ~~~~^~~~~~~~~~~~~~~~~~ vim +/ulp +215 include/linux/compiler.h 230fa253 Christian Borntraeger 2014-11-25 208 43239cbe Christian Borntraeger 2015-01-13 209 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 230fa253 Christian Borntraeger 2014-11-25 210 { 230fa253 Christian Borntraeger 2014-11-25 211 switch (size) { 230fa253 Christian Borntraeger 2014-11-25 212 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 230fa253 Christian Borntraeger 2014-11-25 213 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 230fa253 Christian Borntraeger 2014-11-25 214 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 230fa253 Christian Borntraeger 2014-11-25 @215 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 230fa253 Christian Borntraeger 2014-11-25 216 default: 230fa253 Christian Borntraeger 2014-11-25 217 barrier(); 230fa253 Christian Borntraeger 2014-11-25 218 __builtin_memcpy((void *)p, (const void *)res, size); 230fa253 Christian Borntraeger 2014-11-25 219 barrier(); 230fa253 Christian Borntraeger 2014-11-25 220 } 230fa253 Christian Borntraeger 2014-11-25 221 } 230fa253 Christian Borntraeger 2014-11-25 222 :::::: The code at line 215 was first introduced by commit :::::: 230fa253df6352af12ad0a16128760b5cb3f92df kernel: Provide READ_ONCE and ASSIGN_ONCE :::::: TO: Christian Borntraeger <borntraeger@xxxxxxxxxx> :::::: CC: Christian Borntraeger <borntraeger@xxxxxxxxxx> --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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