[kbuild-all] [arm:cex7 125/143] include/uapi/linux/swab.h:18:38: warning: 'px_is' may be used uninitialized in this function

tree: git://git.armlinux.org.uk/~rmk/linux-arm.git cex7 head: 3f487cad79774a93337d73615e2cd87586b0f7db commit: 25167ffbba96633800ebe64ae7ee3eb17f2a021f [125/143] ahci: qoriq: workaround for errata A-379364 on lx2160a config: h8300-randconfig-a001-20200317 (attached as .config) compiler: h8300-linux-gcc (GCC) 9.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout 25167ffbba96633800ebe64ae7ee3eb17f2a021f # save the attached .config to linux build tree GCC_VERSION=9.2.0 make.cross ARCH=h8300 If you fix the issue, kindly add following tag Reported-by: kbuild test robot <lkp(a)intel.com&gt; 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 include/linux/swab.h:5, from include/uapi/linux/byteorder/big_endian.h:13, from include/linux/byteorder/big_endian.h:5, from arch/h8300/include/asm/byteorder.h:5, from include/asm-generic/bitops/le.h:6, from arch/h8300/include/asm/bitops.h:171, from include/linux/bitops.h:26, from include/linux/kernel.h:12, from drivers/ata/ahci_qoriq.c:9: drivers/ata/ahci_qoriq.c: In function 'ahci_qoriq_hardreset': 18 | (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \ | ^~ drivers/ata/ahci_qoriq.c:229:14: note: 'px_is' was declared here 229 | u32 px_cmd, px_is, px_val; | ^~~~~ In file included from include/linux/swab.h:5, from include/uapi/linux/byteorder/big_endian.h:13, from include/linux/byteorder/big_endian.h:5, from arch/h8300/include/asm/byteorder.h:5, from include/asm-generic/bitops/le.h:6, from arch/h8300/include/asm/bitops.h:171, from include/linux/bitops.h:26, from include/linux/kernel.h:12, from drivers/ata/ahci_qoriq.c:9: 18 | (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \ | ^~ drivers/ata/ahci_qoriq.c:229:6: note: 'px_cmd' was declared here 229 | u32 px_cmd, px_is, px_val; | ^~~~~~ -- In file included from include/linux/swab.h:5, from include/uapi/linux/byteorder/big_endian.h:13, from include/linux/byteorder/big_endian.h:5, from arch/h8300/include/asm/byteorder.h:5, from include/asm-generic/bitops/le.h:6, from arch/h8300/include/asm/bitops.h:171, from include/linux/bitops.h:26, from include/linux/kernel.h:12, from drivers//ata/ahci_qoriq.c:9: drivers//ata/ahci_qoriq.c: In function 'ahci_qoriq_hardreset': 18 | (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \ | ^~ drivers//ata/ahci_qoriq.c:229:14: note: 'px_is' was declared here 229 | u32 px_cmd, px_is, px_val; | ^~~~~ In file included from include/linux/swab.h:5, from include/uapi/linux/byteorder/big_endian.h:13, from include/linux/byteorder/big_endian.h:5, from arch/h8300/include/asm/byteorder.h:5, from include/asm-generic/bitops/le.h:6, from arch/h8300/include/asm/bitops.h:171, from include/linux/bitops.h:26, from include/linux/kernel.h:12, from drivers//ata/ahci_qoriq.c:9: 18 | (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \ | ^~ drivers//ata/ahci_qoriq.c:229:6: note: 'px_cmd' was declared here 229 | u32 px_cmd, px_is, px_val; | ^~~~~~ vim +/px_is +18 include/uapi/linux/swab.h 607ca46e97a1b6 David Howells 2012-10-13 8 607ca46e97a1b6 David Howells 2012-10-13 9 /* 607ca46e97a1b6 David Howells 2012-10-13 10 * casts are necessary for constants, because we never know how for sure 607ca46e97a1b6 David Howells 2012-10-13 11 * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way. 607ca46e97a1b6 David Howells 2012-10-13 12 */ 607ca46e97a1b6 David Howells 2012-10-13 13 #define ___constant_swab16(x) ((__u16)( \ 607ca46e97a1b6 David Howells 2012-10-13 14 (((__u16)(x) & (__u16)0x00ffU) << 8) | \ 607ca46e97a1b6 David Howells 2012-10-13 15 (((__u16)(x) & (__u16)0xff00U) >> 8))) 607ca46e97a1b6 David Howells 2012-10-13 16 607ca46e97a1b6 David Howells 2012-10-13 17 #define ___constant_swab32(x) ((__u32)( \ 607ca46e97a1b6 David Howells 2012-10-13 @18 (((__u32)(x) & (__u32)0x000000ffUL) << 24) | \ 607ca46e97a1b6 David Howells 2012-10-13 19 (((__u32)(x) & (__u32)0x0000ff00UL) << 8) | \ 607ca46e97a1b6 David Howells 2012-10-13 20 (((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | \ 607ca46e97a1b6 David Howells 2012-10-13 21 (((__u32)(x) & (__u32)0xff000000UL) >> 24))) 607ca46e97a1b6 David Howells 2012-10-13 22 :::::: The code at line 18 was first introduced by commit :::::: 607ca46e97a1b6594b29647d98a32d545c24bdff UAPI: (Scripted) Disintegrate include/linux :::::: TO: David Howells <dhowells(a)redhat.com&gt; :::::: CC: David Howells <dhowells(a)redhat.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org