Re: [PATCH v2] arch_topology: Support SMT control on arm64

kernel test robot
2023-10-12T16:11:01Z

Hi Yicong,

kernel test robot noticed the following build errors:

[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on driver-core/driver-core-testing driver-core/driver-core-next driver-core/driver-core-linus soc/for-next linus/master v6.6-rc5 next-20231012]
[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/Yicong-Yang/arch_topology-Support-SMT-control-on-arm64/20231010-195926
base: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
patch link: https://lore.kernel.org/r/20231010115335.13862-1-yangyicong%40huawei.com
patch subject: [PATCH v2] arch_topology: Support SMT control on arm64
config: arm64-allnoconfig (https://download.01.org/0day-ci/archive/20231012/202310122334.INC9SFga-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231012/202310122334.INC9SFga-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/202310122334.INC9SFga-lkp@intel.com/

All errors (new ones prefixed by >>):

kernel/cpu.c: In function 'cpuhp_smt_disable':
>> kernel/cpu.c:2687:23: error: implicit declaration of function 'cpu_down_maps_locked' [-Werror=implicit-function-declaration]
2687 | ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
| ^~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors

vim +/cpu_down_maps_locked +2687 kernel/cpu.c

dc8d37ed304eee Arnd Bergmann 2019-12-10 2672
dc8d37ed304eee Arnd Bergmann 2019-12-10 2673 int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
dc8d37ed304eee Arnd Bergmann 2019-12-10 2674 {
dc8d37ed304eee Arnd Bergmann 2019-12-10 2675 int cpu, ret = 0;
dc8d37ed304eee Arnd Bergmann 2019-12-10 2676
dc8d37ed304eee Arnd Bergmann 2019-12-10 2677 cpu_maps_update_begin();
dc8d37ed304eee Arnd Bergmann 2019-12-10 2678 for_each_online_cpu(cpu) {
dc8d37ed304eee Arnd Bergmann 2019-12-10 2679 if (topology_is_primary_thread(cpu))
dc8d37ed304eee Arnd Bergmann 2019-12-10 2680 continue;
38253464bc821d Michael Ellerman 2023-07-05 2681 /*
38253464bc821d Michael Ellerman 2023-07-05 2682 * Disable can be called with CPU_SMT_ENABLED when changing
38253464bc821d Michael Ellerman 2023-07-05 2683 * from a higher to lower number of SMT threads per core.
38253464bc821d Michael Ellerman 2023-07-05 2684 */
38253464bc821d Michael Ellerman 2023-07-05 2685 if (ctrlval == CPU_SMT_ENABLED && cpu_smt_thread_allowed(cpu))
38253464bc821d Michael Ellerman 2023-07-05 2686 continue;
dc8d37ed304eee Arnd Bergmann 2019-12-10 @2687 ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE);
dc8d37ed304eee Arnd Bergmann 2019-12-10 2688 if (ret)
dc8d37ed304eee Arnd Bergmann 2019-12-10 2689 break;
dc8d37ed304eee Arnd Bergmann 2019-12-10 2690 /*
dc8d37ed304eee Arnd Bergmann 2019-12-10 2691 * As this needs to hold the cpu maps lock it's impossible
dc8d37ed304eee Arnd Bergmann 2019-12-10 2692 * to call device_offline() because that ends up calling
dc8d37ed304eee Arnd Bergmann 2019-12-10 2693 * cpu_down() which takes cpu maps lock. cpu maps lock
dc8d37ed304eee Arnd Bergmann 2019-12-10 2694 * needs to be held as this might race against in kernel
dc8d37ed304eee Arnd Bergmann 2019-12-10 2695 * abusers of the hotplug machinery (thermal management).
dc8d37ed304eee Arnd Bergmann 2019-12-10 2696 *
dc8d37ed304eee Arnd Bergmann 2019-12-10 2697 * So nothing would update device:offline state. That would
dc8d37ed304eee Arnd Bergmann 2019-12-10 2698 * leave the sysfs entry stale and prevent onlining after
dc8d37ed304eee Arnd Bergmann 2019-12-10 2699 * smt control has been changed to 'off' again. This is
dc8d37ed304eee Arnd Bergmann 2019-12-10 2700 * called under the sysfs hotplug lock, so it is properly
dc8d37ed304eee Arnd Bergmann 2019-12-10 2701 * serialized against the regular offline usage.
dc8d37ed304eee Arnd Bergmann 2019-12-10 2702 */
dc8d37ed304eee Arnd Bergmann 2019-12-10 2703 cpuhp_offline_cpu_device(cpu);
dc8d37ed304eee Arnd Bergmann 2019-12-10 2704 }
dc8d37ed304eee Arnd Bergmann 2019-12-10 2705 if (!ret)
dc8d37ed304eee Arnd Bergmann 2019-12-10 2706 cpu_smt_control = ctrlval;
dc8d37ed304eee Arnd Bergmann 2019-12-10 2707 cpu_maps_update_done();
dc8d37ed304eee Arnd Bergmann 2019-12-10 2708 return ret;
dc8d37ed304eee Arnd Bergmann 2019-12-10 2709 }
dc8d37ed304eee Arnd Bergmann 2019-12-10 2710

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