[kkdwivedi:cna 6/6] kernel/locking/qspinlock_cna.h:102:6: error: call to undeclared function 'next_pseudo_random32'; ISO C99 and later do not support implicit function declarations

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

tree:   https://github.com/kkdwivedi/linux cna
head:   7b55d75d53fa4712c9c480318d248c4bf3dbe1e4
commit: 7b55d75d53fa4712c9c480318d248c4bf3dbe1e4 [6/6] locking/qspinlock: Introduce the shuffle reduction optimization into CNA
config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20250219/202502190755.HSNSt2IQ-lkp@intel.com/config)
compiler: clang version 19.1.3 (https://github.com/llvm/llvm-project ab51eccf88f5321e7c60591c5546b254b6afab99)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250219/202502190755.HSNSt2IQ-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/202502190755.HSNSt2IQ-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from kernel/locking/qspinlock.c:621:
>> kernel/locking/qspinlock_cna.h:102:6: error: call to undeclared function 'next_pseudo_random32'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     102 |         s = next_pseudo_random32(s);
         |             ^
   In file included from kernel/locking/qspinlock.c:624:
   In file included from kernel/locking/qspinlock.c:651:
   In file included from kernel/locking/qspinlock_paravirt.h:7:
   In file included from include/linux/memblock.h:12:
   In file included from include/linux/mm.h:2224:
   include/linux/vmstat.h:504:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
     504 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~ ^
     505 |                            item];
         |                            ~~~~
   include/linux/vmstat.h:511:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
     511 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~ ^
     512 |                            NR_VM_NUMA_EVENT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~~
   include/linux/vmstat.h:524:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
     524 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~ ^
     525 |                            NR_VM_NUMA_EVENT_ITEMS +
         |                            ~~~~~~~~~~~~~~~~~~~~~~
   3 warnings and 1 error generated.


vim +/next_pseudo_random32 +102 kernel/locking/qspinlock_cna.h

    91	
    92	/*
    93	 * Return false with probability 1 / 2^@num_bits.
    94	 * Intuitively, the larger @num_bits the less likely false is to be returned.
    95	 * @num_bits must be a number between 0 and 31.
    96	 */
    97	static bool probably(unsigned int num_bits)
    98	{
    99		u32 s;
   100	
   101		s = this_cpu_read(seed);
 > 102		s = next_pseudo_random32(s);
   103		this_cpu_write(seed, s);
   104	
   105		return s & ((1 << num_bits) - 1);
   106	}
   107	

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