Re: [PATCH] LoongArch: Use polling play_dead() when resuming from hibernation

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

Hi Huacai,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.14-rc4 next-20250227]
[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/Huacai-Chen/LoongArch-Use-polling-play_dead-when-resuming-from-hibernation/20250225-192024
base:   linus/master
patch link:    https://lore.kernel.org/r/20250225111812.3065545-1-chenhuacai%40loongson.cn
patch subject: [PATCH] LoongArch: Use polling play_dead() when resuming from hibernation
config: loongarch-randconfig-001-20250227 (https://download.01.org/0day-ci/archive/20250228/202502280356.YjzMIJ8n-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250228/202502280356.YjzMIJ8n-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/202502280356.YjzMIJ8n-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> arch/loongarch/kernel/smp.c:451:24: warning: 'poll_play_dead' defined but not used [-Wunused-function]
     451 | static void __noreturn poll_play_dead(void)
         |                        ^~~~~~~~~~~~~~


vim +/poll_play_dead +451 arch/loongarch/kernel/smp.c

   450	
 > 451	static void __noreturn poll_play_dead(void)
   452	{
   453		register uint64_t addr;
   454		register void (*init_fn)(void);
   455	
   456		idle_task_exit();
   457		__this_cpu_write(cpu_state, CPU_DEAD);
   458	
   459		__smp_mb();
   460		do {
   461			__asm__ __volatile__("nop\n\t");
   462			addr = iocsr_read64(LOONGARCH_IOCSR_MBUF0);
   463		} while (addr == 0);
   464	
   465		init_fn = (void *)TO_CACHE(addr);
   466		iocsr_write32(0xffffffff, LOONGARCH_IOCSR_IPI_CLEAR);
   467	
   468		init_fn();
   469		BUG();
   470	}
   471	

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