Re: [PATCH] sched/fair: Optimize EAS energy calculation complexity from O(N) to O(1) inside inner loop

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

Hi Qiliang,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/sched/core]
[also build test WARNING on tip/master peterz-queue/sched/core linus/master v6.16-rc1 next-20260122]
[cannot apply to tip/auto-latest]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Qiliang-Yuan/sched-fair-Optimize-EAS-energy-calculation-complexity-from-O-N-to-O-1-inside-inner-loop/20260123-000924
base:   tip/sched/core
patch link:    https://lore.kernel.org/r/20260122154227.130767-1-realwujing%40gmail.com
patch subject: [PATCH] sched/fair: Optimize EAS energy calculation complexity from O(N) to O(1) inside inner loop
config: s390-allnoconfig-bpf (https://download.01.org/0day-ci/archive/20260123/202601231209.7Aqyec0v-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260123/202601231209.7Aqyec0v-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601231209.7Aqyec0v-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from ./include/linux/bitmap.h:11,
                    from ./include/linux/cpumask.h:11,
                    from ./include/linux/energy_model.h:4,
                    from kernel/sched/fair.c:23:
   kernel/sched/fair.c: In function 'find_energy_efficient_cpu':
   ./include/linux/cpumask_types.h:18:37: warning: dereferencing 'void *' pointer
      18 | #define cpumask_bits(maskp) ((maskp)->bits)
         |                                     ^~
   ./include/linux/find.h:586:48: note: in definition of macro 'for_each_set_bit'
     586 |         for ((bit) = 0; (bit) = find_next_bit((addr), (size), (bit)), (bit) < (size); (bit)++)
         |                                                ^~~~
   ./include/linux/cpumask.h:380:31: note: in expansion of macro 'cpumask_bits'
     380 |         for_each_set_bit(cpu, cpumask_bits(mask), small_cpumask_bits)
         |                               ^~~~~~~~~~~~
   kernel/sched/fair.c:8345:17: note: in expansion of macro 'for_each_cpu'
    8345 |                 for_each_cpu(i, perf_domain_span(tmp_pd)) {
         |                 ^~~~~~~~~~~~
   ./include/linux/cpumask_types.h:18:37: error: request for member 'bits' in something not a structure or union
      18 | #define cpumask_bits(maskp) ((maskp)->bits)
         |                                     ^~
   ./include/linux/find.h:586:48: note: in definition of macro 'for_each_set_bit'
     586 |         for ((bit) = 0; (bit) = find_next_bit((addr), (size), (bit)), (bit) < (size); (bit)++)
         |                                                ^~~~
   ./include/linux/cpumask.h:380:31: note: in expansion of macro 'cpumask_bits'
     380 |         for_each_set_bit(cpu, cpumask_bits(mask), small_cpumask_bits)
         |                               ^~~~~~~~~~~~
   kernel/sched/fair.c:8345:17: note: in expansion of macro 'for_each_cpu'
    8345 |                 for_each_cpu(i, perf_domain_span(tmp_pd)) {
         |                 ^~~~~~~~~~~~
>> ./include/linux/find.h:586:69: warning: left-hand operand of comma expression has no effect [-Wunused-value]
     586 |         for ((bit) = 0; (bit) = find_next_bit((addr), (size), (bit)), (bit) < (size); (bit)++)
         |                                                                     ^
   ./include/linux/cpumask.h:380:9: note: in expansion of macro 'for_each_set_bit'
     380 |         for_each_set_bit(cpu, cpumask_bits(mask), small_cpumask_bits)
         |         ^~~~~~~~~~~~~~~~
   kernel/sched/fair.c:8345:17: note: in expansion of macro 'for_each_cpu'
    8345 |                 for_each_cpu(i, perf_domain_span(tmp_pd)) {
         |                 ^~~~~~~~~~~~


vim +586 ./include/linux/find.h

6b8ecb84f8f640 include/asm-generic/bitops/find.h Yury Norov 2021-08-14  584  
bc9d6635c293a2 include/linux/find.h              Yury Norov 2021-08-14  585  #define for_each_set_bit(bit, addr, size) \
fdae96a3fc7f70 include/linux/find.h              Yury Norov 2022-09-19 @586  	for ((bit) = 0; (bit) = find_next_bit((addr), (size), (bit)), (bit) < (size); (bit)++)
bc9d6635c293a2 include/linux/find.h              Yury Norov 2021-08-14  587  

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