Messages in this thread | | | Date | Thu, 25 Aug 2022 12:30:10 +0800 | From | kernel test robot <> | Subject | [ammarfaizi2-block:akpm/mm/mm-nonmm-unstable 50/50] kernel/smpboot.c:435:6: warning: variable 'oldstate' is used uninitialized whenever 'if' condition is true |
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Hi Uros,
FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.
tree: https://github.com/ammarfaizi2/linux-block akpm/mm/mm-nonmm-unstable head: 2d1e07c7534c14e56ac3818fa24e7c1643a9b1dc commit: 2d1e07c7534c14e56ac3818fa24e7c1643a9b1dc [50/50] smpboot: use atomic_try_cmpxchg in cpu_wait_death and cpu_report_death config: x86_64-randconfig-a003 (https://download.01.org/0day-ci/archive/20220825/202208251224.teVMa7Yy-lkp@intel.com/config) compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1) 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 # https://github.com/ammarfaizi2/linux-block/commit/2d1e07c7534c14e56ac3818fa24e7c1643a9b1dc git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block git fetch --no-tags ammarfaizi2-block akpm/mm/mm-nonmm-unstable git checkout 2d1e07c7534c14e56ac3818fa24e7c1643a9b1dc # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> kernel/smpboot.c:435:6: warning: variable 'oldstate' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) == CPU_DEAD) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/smpboot.c:449:6: note: uninitialized use occurs here if (oldstate == CPU_DEAD) { ^~~~~~~~ kernel/smpboot.c:435:2: note: remove the 'if' if its condition is always false if (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) == CPU_DEAD) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/smpboot.c:428:14: note: initialize the variable 'oldstate' to silence this warning int oldstate; ^ = 0 1 warning generated.
vim +435 kernel/smpboot.c
8038dad7e88858 Paul E. McKenney 2015-02-25 421 8038dad7e88858 Paul E. McKenney 2015-02-25 422 /* 8038dad7e88858 Paul E. McKenney 2015-02-25 423 * Wait for the specified CPU to exit the idle loop and die. 8038dad7e88858 Paul E. McKenney 2015-02-25 424 */ 8038dad7e88858 Paul E. McKenney 2015-02-25 425 bool cpu_wait_death(unsigned int cpu, int seconds) 8038dad7e88858 Paul E. McKenney 2015-02-25 426 { 8038dad7e88858 Paul E. McKenney 2015-02-25 427 int jf_left = seconds * HZ; 8038dad7e88858 Paul E. McKenney 2015-02-25 428 int oldstate; 8038dad7e88858 Paul E. McKenney 2015-02-25 429 bool ret = true; 8038dad7e88858 Paul E. McKenney 2015-02-25 430 int sleep_jf = 1; 8038dad7e88858 Paul E. McKenney 2015-02-25 431 8038dad7e88858 Paul E. McKenney 2015-02-25 432 might_sleep(); 8038dad7e88858 Paul E. McKenney 2015-02-25 433 8038dad7e88858 Paul E. McKenney 2015-02-25 434 /* The outgoing CPU will normally get done quite quickly. */ 8038dad7e88858 Paul E. McKenney 2015-02-25 @435 if (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) == CPU_DEAD) 8038dad7e88858 Paul E. McKenney 2015-02-25 436 goto update_state; 8038dad7e88858 Paul E. McKenney 2015-02-25 437 udelay(5); 8038dad7e88858 Paul E. McKenney 2015-02-25 438 8038dad7e88858 Paul E. McKenney 2015-02-25 439 /* But if the outgoing CPU dawdles, wait increasingly long times. */ 8038dad7e88858 Paul E. McKenney 2015-02-25 440 while (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) != CPU_DEAD) { 8038dad7e88858 Paul E. McKenney 2015-02-25 441 schedule_timeout_uninterruptible(sleep_jf); 8038dad7e88858 Paul E. McKenney 2015-02-25 442 jf_left -= sleep_jf; 8038dad7e88858 Paul E. McKenney 2015-02-25 443 if (jf_left <= 0) 8038dad7e88858 Paul E. McKenney 2015-02-25 444 break; 8038dad7e88858 Paul E. McKenney 2015-02-25 445 sleep_jf = DIV_ROUND_UP(sleep_jf * 11, 10); 8038dad7e88858 Paul E. McKenney 2015-02-25 446 } 8038dad7e88858 Paul E. McKenney 2015-02-25 447 oldstate = atomic_read(&per_cpu(cpu_hotplug_state, cpu)); 2d1e07c7534c14 Uros Bizjak 2022-08-23 448 update_state: 8038dad7e88858 Paul E. McKenney 2015-02-25 449 if (oldstate == CPU_DEAD) { 8038dad7e88858 Paul E. McKenney 2015-02-25 450 /* Outgoing CPU died normally, update state. */ 8038dad7e88858 Paul E. McKenney 2015-02-25 451 smp_mb(); /* atomic_read() before update. */ 8038dad7e88858 Paul E. McKenney 2015-02-25 452 atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_POST_DEAD); 8038dad7e88858 Paul E. McKenney 2015-02-25 453 } else { 8038dad7e88858 Paul E. McKenney 2015-02-25 454 /* Outgoing CPU still hasn't died, set state accordingly. */ 2d1e07c7534c14 Uros Bizjak 2022-08-23 455 if (!atomic_try_cmpxchg(&per_cpu(cpu_hotplug_state, cpu), 2d1e07c7534c14 Uros Bizjak 2022-08-23 456 &oldstate, CPU_BROKEN)) 8038dad7e88858 Paul E. McKenney 2015-02-25 457 goto update_state; 8038dad7e88858 Paul E. McKenney 2015-02-25 458 ret = false; 8038dad7e88858 Paul E. McKenney 2015-02-25 459 } 8038dad7e88858 Paul E. McKenney 2015-02-25 460 return ret; 8038dad7e88858 Paul E. McKenney 2015-02-25 461 } 8038dad7e88858 Paul E. McKenney 2015-02-25 462
:::::: The code at line 435 was first introduced by commit :::::: 8038dad7e888581266c76df15d70ca457a3c5910 smpboot: Add common code for notification from dying CPU
:::::: TO: Paul E. McKenney <paulmck@linux.vnet.ibm.com> :::::: CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-- 0-DAY CI Kernel Test Service https://01.org/lkp
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