tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2021.05.02a
head:   35d2c62851bc03a945ae81ab0726985f726107b1
commit: 35d2c62851bc03a945ae81ab0726985f726107b1 [114/114] refscale: Add measurement of clock readout
config: nios2-randconfig-r014-20210505 (attached as .config)
compiler: nios2-linux-gcc (GCC) 9.3.0
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://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=35d2c62851bc03a945ae81ab0726985f726107b1
        git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
        git fetch --no-tags rcu dev.2021.05.02a
        git checkout 35d2c62851bc03a945ae81ab0726985f726107b1
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=nios2 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   kernel/rcu/refscale.c: In function 'ref_clock_section':
>> kernel/rcu/refscale.c:472:15: warning: variable 'x' set but not used [-Wunused-but-set-variable]
     472 |  volatile u64 x;
         |               ^
   kernel/rcu/refscale.c: In function 'ref_clock_delay_section':
   kernel/rcu/refscale.c:484:15: warning: variable 'x' set but not used [-Wunused-but-set-variable]
     484 |  volatile u64 x;
         |               ^


vim +/x +472 kernel/rcu/refscale.c

   469	
   470	static void ref_clock_section(const int nloops)
   471	{
 > 472		volatile u64 x;
   473		int i;
   474	
   475		preempt_disable();
   476		for (i = nloops; i >= 0; i--) {
   477			x = ktime_get_real_fast_ns();
   478		}
   479		preempt_enable();
   480	}
   481	

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