Re: [PATCH v2] sched/core: add forced idle accounting for cgroups

[kernel test robot <lkp@intel.com>]

Hi Josh,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tj-cgroup/for-next]
[also build test WARNING on tip/sched/core tip/master v5.18-rc7 next-20220520]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/intel-lab-lkp/linux/commits/Josh-Don/sched-core-add-forced-idle-accounting-for-cgroups/20220521-075311
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-next
config: hexagon-randconfig-r033-20220519 (https://download.01.org/0day-ci/archive/20220521/202205211029.u32ZBjjj-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project b369762beb70dfef22c7e793aed79b94d7dc0757)
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/intel-lab-lkp/linux/commit/0575a42c9f10cda618b09b949cc42fe97abea479
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Josh-Don/sched-core-add-forced-idle-accounting-for-cgroups/20220521-075311
        git checkout 0575a42c9f10cda618b09b949cc42fe97abea479
        # 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=hexagon SHELL=/bin/bash kernel/cgroup/

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/cgroup/rstat.c:489:9: warning: variable 'forceidle_time' is uninitialized when used here [-Wuninitialized]
           do_div(forceidle_time, NSEC_PER_USEC);
                  ^~~~~~~~~~~~~~
   include/asm-generic/div64.h:225:12: note: expanded from macro 'do_div'
                   __rem = (n) & (__base - 1);             \
                            ^
   kernel/cgroup/rstat.c:465:35: note: initialize the variable 'forceidle_time' to silence this warning
           u64 __maybe_unused forceidle_time;
                                            ^
                                             = 0
   1 warning generated.


vim +/forceidle_time +489 kernel/cgroup/rstat.c

   459	
   460	void cgroup_base_stat_cputime_show(struct seq_file *seq)
   461	{
   462		struct cgroup *cgrp = seq_css(seq)->cgroup;
   463		u64 usage, utime, stime;
   464		struct cgroup_base_stat bstat;
   465		u64 __maybe_unused forceidle_time;
   466	
   467		if (cgroup_parent(cgrp)) {
   468			cgroup_rstat_flush_hold(cgrp);
   469			usage = cgrp->bstat.cputime.sum_exec_runtime;
   470			cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
   471				       &utime, &stime);
   472	#ifdef CONFIG_SCHED_CORE
   473			forceidle_time = cgrp->bstat.forceidle_sum;
   474	#endif
   475			cgroup_rstat_flush_release();
   476		} else {
   477			root_cgroup_cputime(&bstat);
   478			usage = bstat.cputime.sum_exec_runtime;
   479			utime = bstat.cputime.utime;
   480			stime = bstat.cputime.stime;
   481	#ifdef CONFIG_SCHED_CORE
   482			forceidle_time = bstat.forceidle_sum;
   483	#endif
   484		}
   485	
   486		do_div(usage, NSEC_PER_USEC);
   487		do_div(utime, NSEC_PER_USEC);
   488		do_div(stime, NSEC_PER_USEC);
 > 489		do_div(forceidle_time, NSEC_PER_USEC);
   490	
   491		seq_printf(seq, "usage_usec %llu\n"
   492			   "user_usec %llu\n"
   493			   "system_usec %llu\n",
   494			   usage, utime, stime);
   495	

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