[PATCH] powerpc/kexec: Enable SMT before waking offline CPUs

[kernel test robot]

Hi Nysal,

kernel test robot noticed the following build errors:

[auto build test ERROR on powerpc/next]
[also build test ERROR on powerpc/fixes linus/master v6.18-rc3 next-20251027]
[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/Nysal-Jan-K-A/powerpc-kexec-Enable-SMT-before-waking-offline-CPUs/20251025-160821
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
patch link:    https://lore.kernel.org/r/20251025080512.85690-1-nysal%40linux.ibm.com
patch subject: [PATCH] powerpc/kexec: Enable SMT before waking offline CPUs
config: powerpc64-randconfig-001-20251028 (https://download.01.org/0day-ci/archive/20251028/202510280824.Fe2D1Sbw-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project e1ae12640102fd2b05bc567243580f90acb1135f)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251028/202510280824.Fe2D1Sbw-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 at intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510280824.Fe2D1Sbw-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from <built-in>:3:
   In file included from include/linux/compiler_types.h:171:
   include/linux/compiler-clang.h:37:9: warning: '__SANITIZE_THREAD__' macro redefined [-Wmacro-redefined]
      37 | #define __SANITIZE_THREAD__
         |         ^
   <built-in>:353:9: note: previous definition is here
     353 | #define __SANITIZE_THREAD__ 1
         |         ^
>> arch/powerpc/kexec/core_64.c:220:22: error: expression is not assignable
     220 |         cpu_smt_num_threads = threads_per_core;
         |         ~~~~~~~~~~~~~~~~~~~ ^
   arch/powerpc/kexec/core_64.c:221:18: error: expression is not assignable
     221 |         cpu_smt_control = CPU_SMT_ENABLED;
         |         ~~~~~~~~~~~~~~~ ^
   1 warning and 2 errors generated.


vim +220 arch/powerpc/kexec/core_64.c

   204	
   205	/*
   206	 * We need to make sure each present CPU is online.  The next kernel will scan
   207	 * the device tree and assume primary threads are online and query secondary
   208	 * threads via RTAS to online them if required.  If we don't online primary
   209	 * threads, they will be stuck.  However, we also online secondary threads as we
   210	 * may be using 'cede offline'.  In this case RTAS doesn't see the secondary
   211	 * threads as offline -- and again, these CPUs will be stuck.
   212	 *
   213	 * So, we online all CPUs that should be running, including secondary threads.
   214	 */
   215	static void wake_offline_cpus(void)
   216	{
   217		int cpu = 0;
   218	
   219		lock_device_hotplug();
 > 220		cpu_smt_num_threads = threads_per_core;
   221		cpu_smt_control = CPU_SMT_ENABLED;
   222		unlock_device_hotplug();
   223	
   224		for_each_present_cpu(cpu) {
   225			if (!cpu_online(cpu)) {
   226				printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
   227				       cpu);
   228				WARN_ON(add_cpu(cpu));
   229			}
   230		}
   231	}
   232	

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