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, 15 insertions, 54 deletions

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 7f3550acde1b..f5e3ff835cc8 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -44,6 +44,7 @@
 #include <asm/msr.h>
 
 static struct class *msr_class;
+static enum cpuhp_state cpuhp_msr_state;
 
 static ssize_t msr_read(struct file *file, char __user *buf,
 			size_t count, loff_t *ppos)
@@ -180,7 +181,7 @@ static const struct file_operations msr_fops = {
 	.compat_ioctl = msr_ioctl,
 };
 
-static int msr_device_create(int cpu)
+static int msr_device_create(unsigned int cpu)
 {
 	struct device *dev;
 
@@ -189,34 +190,12 @@ static int msr_device_create(int cpu)
 	return PTR_ERR_OR_ZERO(dev);
 }
 
-static void msr_device_destroy(int cpu)
+static int msr_device_destroy(unsigned int cpu)
 {
 	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
+	return 0;
 }
 
-static int msr_class_cpu_callback(struct notifier_block *nfb,
-				  unsigned long action, void *hcpu)
-{
-	unsigned int cpu = (unsigned long)hcpu;
-	int err = 0;
-
-	switch (action) {
-	case CPU_UP_PREPARE:
-		err = msr_device_create(cpu);
-		break;
-	case CPU_UP_CANCELED:
-	case CPU_UP_CANCELED_FROZEN:
-	case CPU_DEAD:
-		msr_device_destroy(cpu);
-		break;
-	}
-	return notifier_from_errno(err);
-}
-
-static struct notifier_block __refdata msr_class_cpu_notifier = {
-	.notifier_call = msr_class_cpu_callback,
-};
-
 static char *msr_devnode(struct device *dev, umode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
@@ -224,13 +203,11 @@ static char *msr_devnode(struct device *dev, umode_t *mode)
 
 static int __init msr_init(void)
 {
-	int i, err = 0;
-	i = 0;
+	int err;
 
 	if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
 		pr_err("unable to get major %d for msr\n", MSR_MAJOR);
-		err = -EBUSY;
-		goto out;
+		return -EBUSY;
 	}
 	msr_class = class_create(THIS_MODULE, "msr");
 	if (IS_ERR(msr_class)) {
@@ -239,44 +216,28 @@ static int __init msr_init(void)
 	}
 	msr_class->devnode = msr_devnode;
 
-	cpu_notifier_register_begin();
-	for_each_online_cpu(i) {
-		err = msr_device_create(i);
-		if (err != 0)
-			goto out_class;
-	}
-	__register_hotcpu_notifier(&msr_class_cpu_notifier);
-	cpu_notifier_register_done();
-
-	err = 0;
-	goto out;
+	err  = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/msr:online",
+				 msr_device_create, msr_device_destroy);
+	if (err < 0)
+		goto out_class;
+	cpuhp_msr_state = err;
+	return 0;
 
 out_class:
-	i = 0;
-	for_each_online_cpu(i)
-		msr_device_destroy(i);
-	cpu_notifier_register_done();
+	cpuhp_remove_state(cpuhp_msr_state);
 	class_destroy(msr_class);
 out_chrdev:
 	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
-out:
 	return err;
 }
+module_init(msr_init);
 
 static void __exit msr_exit(void)
 {
-	int cpu = 0;
-
-	cpu_notifier_register_begin();
-	for_each_online_cpu(cpu)
-		msr_device_destroy(cpu);
+	cpuhp_remove_state(cpuhp_msr_state);
 	class_destroy(msr_class);
 	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
-	__unregister_hotcpu_notifier(&msr_class_cpu_notifier);
-	cpu_notifier_register_done();
 }
-
-module_init(msr_init);
 module_exit(msr_exit)
 
 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");