Hi Ming,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/irq/core]
[also build test WARNING on next-20210813]
[cannot apply to block/for-next linux/master linus/master v5.14-rc5]
[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/0day-ci/linux/commits/Ming-Lei/genirq-affinity-abstract-new-API-from-managed-irq-affinity-spread/20210814-203741
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 04c2721d3530f0723b4c922a8fa9f26b202a20de
config: arc-randconfig-r016-20210814 (attached as .config)
compiler: arc-elf-gcc (GCC) 11.2.0
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/0day-ci/linux/commit/759f72186bfdd5c3ba8b53ac0749cf7ba930012c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Ming-Lei/genirq-affinity-abstract-new-API-from-managed-irq-affinity-spread/20210814-203741
        git checkout 759f72186bfdd5c3ba8b53ac0749cf7ba930012c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=arc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All warnings (new ones prefixed by >>):

quoted

lib/group_cpus.c:344:17: warning: no previous prototype for 'group_cpus_evenly' [-Wmissing-prototypes]

     344 | struct cpumask *group_cpus_evenly(unsigned int numgrps)
         |                 ^~~~~~~~~~~~~~~~~


vim +/group_cpus_evenly +344 lib/group_cpus.c

   328	
   329	/**
   330	 * group_cpus_evenly - Group all CPUs evenly per NUMA/CPU locality
   331	 * @numgrps: number of groups
   332	 *
   333	 * Return: cpumask array if successful, NULL otherwise. And each element
   334	 * includes CPUs assigned to this group
   335	 *
   336	 * Try to put close CPUs from viewpoint of CPU and NUMA locality into
   337	 * same group, and run two-stage grouping:
   338	 *	1) allocate present CPUs on these groups evenly first
   339	 *	2) allocate other possible CPUs on these groups evenly
   340	 *
   341	 * We guarantee in the resulted grouping that all CPUs are covered, and
   342	 * no same CPU is assigned to different groups
   343	 */
 > 344	struct cpumask *group_cpus_evenly(unsigned int numgrps)

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org