* [intel-linux-intel-lts:5.4/yocto 1/2] arch/x86/kernel/tsc.c:1263:6: warning: variable 'rem' is used uninitialized whenever 'if' condition is false
@ 2021-06-25 15:46 kernel test robot
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From: kernel test robot @ 2021-06-25 15:46 UTC (permalink / raw)
To: kbuild-all
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tree: https://github.com/intel/linux-intel-lts.git 5.4/yocto
head: 53cbd8c20c3f8e8afcc3482e6dd4c9400fc77dcd
commit: 056abbf6314ea7d95396062560c605f172e7535e [1/2] ptp: PSE TGPIO IOCTLs fix
config: x86_64-randconfig-r013-20210625 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 9ca0171a9ffdef5fdb1511d197a3fd72490362de)
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
# install x86_64 cross compiling tool for clang build
# apt-get install binutils-x86-64-linux-gnu
# https://github.com/intel/linux-intel-lts/commit/056abbf6314ea7d95396062560c605f172e7535e
git remote add intel-linux-intel-lts https://github.com/intel/linux-intel-lts.git
git fetch --no-tags intel-linux-intel-lts 5.4/yocto
git checkout 056abbf6314ea7d95396062560c605f172e7535e
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> arch/x86/kernel/tsc.c:1263:6: warning: variable 'rem' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (art_to_tsc_numerator)
^~~~~~~~~~~~~~~~~~~~
arch/x86/kernel/tsc.c:1267:8: note: uninitialized use occurs here
tmp = rem * art_to_tsc_denominator;
^~~
arch/x86/kernel/tsc.c:1263:2: note: remove the 'if' if its condition is always true
if (art_to_tsc_numerator)
^~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/kernel/tsc.c:1257:19: note: initialize the variable 'rem' to silence this warning
u64 tmp, res, rem;
^
= 0
1 warning generated.
vim +1263 arch/x86/kernel/tsc.c
1244
1245 /**
1246 * convert_tsc_to_art() - Returns ART value associated with system counter
1247 *
1248 * Converts input TSC to the corresponding ART value using conversion
1249 * factors discovered by detect_art()
1250 *
1251 * Return:
1252 * u64 ART value
1253 */
1254 int convert_tsc_to_art(const struct system_counterval_t *system_counter,
1255 u64 *art)
1256 {
1257 u64 tmp, res, rem;
1258
1259 if (system_counter->cs != art_related_clocksource)
1260 return -EINVAL;
1261
1262 res = system_counter->cycles - art_to_tsc_offset;
> 1263 if (art_to_tsc_numerator)
1264 rem = do_div(res, art_to_tsc_numerator);
1265
1266 *art = res * art_to_tsc_denominator;
1267 tmp = rem * art_to_tsc_denominator;
1268
1269 if (art_to_tsc_numerator)
1270 do_div(tmp, art_to_tsc_numerator);
1271 *art += tmp;
1272
1273 return 0;
1274 }
1275 EXPORT_SYMBOL(convert_tsc_to_art);
1276
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
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2021-06-25 15:46 [intel-linux-intel-lts:5.4/yocto 1/2] arch/x86/kernel/tsc.c:1263:6: warning: variable 'rem' is used uninitialized whenever 'if' condition is false kernel test robot
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