Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull smp hotplug updates from Thomas Gleixner:
 "This is the final round of converting the notifier mess to the state
  machine. The removal of the notifiers and the related infrastructure
  will happen around rc1, as there are conversions outstanding in other
  trees.

  The whole exercise removed about 2000 lines of code in total and in
  course of the conversion several dozen bugs got fixed. The new
  mechanism allows to test almost every hotplug step standalone, so
  usage sites can exercise all transitions extensively.

  There is more room for improvement, like integrating all the
  pointlessly different architecture mechanisms of synchronizing,
  setting cpus online etc into the core code"

* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
  tracing/rb: Init the CPU mask on allocation
  soc/fsl/qbman: Convert to hotplug state machine
  soc/fsl/qbman: Convert to hotplug state machine
  zram: Convert to hotplug state machine
  KVM/PPC/Book3S HV: Convert to hotplug state machine
  arm64/cpuinfo: Convert to hotplug state machine
  arm64/cpuinfo: Make hotplug notifier symmetric
  mm/compaction: Convert to hotplug state machine
  iommu/vt-d: Convert to hotplug state machine
  mm/zswap: Convert pool to hotplug state machine
  mm/zswap: Convert dst-mem to hotplug state machine
  mm/zsmalloc: Convert to hotplug state machine
  mm/vmstat: Convert to hotplug state machine
  mm/vmstat: Avoid on each online CPU loops
  mm/vmstat: Drop get_online_cpus() from init_cpu_node_state/vmstat_cpu_dead()
  tracing/rb: Convert to hotplug state machine
  oprofile/nmi timer: Convert to hotplug state machine
  net/iucv: Use explicit clean up labels in iucv_init()
  x86/pci/amd-bus: Convert to hotplug state machine
  x86/oprofile/nmi: Convert to hotplug state machine
  ...

1 files changed, 9 insertions, 27 deletions

diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index b3d5b3e8fbcb..7b7be71e87bf 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -227,7 +227,7 @@ static struct attribute_group cpuregs_attr_group = {
 	.name = "identification"
 };
 
-static int cpuid_add_regs(int cpu)
+static int cpuid_cpu_online(unsigned int cpu)
 {
 	int rc;
 	struct device *dev;
@@ -248,7 +248,7 @@ out:
 	return rc;
 }
 
-static int cpuid_remove_regs(int cpu)
+static int cpuid_cpu_offline(unsigned int cpu)
 {
 	struct device *dev;
 	struct cpuinfo_arm64 *info = &per_cpu(cpu_data, cpu);
@@ -264,40 +264,22 @@ static int cpuid_remove_regs(int cpu)
 	return 0;
 }
 
-static int cpuid_callback(struct notifier_block *nb,
-			 unsigned long action, void *hcpu)
-{
-	int rc = 0;
-	unsigned long cpu = (unsigned long)hcpu;
-
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_ONLINE:
-		rc = cpuid_add_regs(cpu);
-		break;
-	case CPU_DEAD:
-		rc = cpuid_remove_regs(cpu);
-		break;
-	}
-
-	return notifier_from_errno(rc);
-}
-
 static int __init cpuinfo_regs_init(void)
 {
-	int cpu;
-
-	cpu_notifier_register_begin();
+	int cpu, ret;
 
 	for_each_possible_cpu(cpu) {
 		struct cpuinfo_arm64 *info = &per_cpu(cpu_data, cpu);
 
 		kobject_init(&info->kobj, &cpuregs_kobj_type);
-		if (cpu_online(cpu))
-			cpuid_add_regs(cpu);
 	}
-	__hotcpu_notifier(cpuid_callback, 0);
 
-	cpu_notifier_register_done();
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm64/cpuinfo:online",
+				cpuid_cpu_online, cpuid_cpu_offline);
+	if (ret < 0) {
+		pr_err("cpuinfo: failed to register hotplug callbacks.\n");
+		return ret;
+	}
 	return 0;
 }
 static void cpuinfo_detect_icache_policy(struct cpuinfo_arm64 *info)