[PATCH 8/10] cpuid: fix cpu hotplug error handling

[Akinobu Mita <akinobu.mita@gmail.com>]

Make cpuid_device_create() CPU_UP_PREPARE event handler
instead of CPU_ONLINE event handler.

Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

---
 arch/i386/kernel/cpuid.c |   32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

Index: 2.6-mm/arch/i386/kernel/cpuid.c
===================================================================
--- 2.6-mm.orig/arch/i386/kernel/cpuid.c
+++ 2.6-mm/arch/i386/kernel/cpuid.c
@@ -152,32 +152,38 @@ static const struct file_operations cpui
 	.open = cpuid_open,
 };
 
-static int cpuid_device_create(int i)
+static int cpuid_device_create(int cpu)
 {
-	int err = 0;
 	struct device *dev;
 
-	dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, i), "cpu%d",i);
-	if (IS_ERR(dev))
-		err = PTR_ERR(dev);
-	return err;
+	dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu),
+			    "cpu%d", cpu);
+	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
+}
+
+static void cpuid_device_destroy(int cpu)
+{
+	device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
 }
 
 static int cpuid_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_ONLINE:
-	case CPU_ONLINE_FROZEN:
-		cpuid_device_create(cpu);
+	case CPU_UP_PREPARE:
+	case CPU_UP_PREPARE_FROZEN:
+		err = cpuid_device_create(cpu);
 		break;
+	case CPU_UP_CANCELED:
+	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
-		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
+		cpuid_device_destroy(cpu);
 		break;
 	}
-	return NOTIFY_OK;
+	return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
 static struct notifier_block __cpuinitdata cpuid_class_cpu_notifier =
@@ -214,7 +220,7 @@ static int __init cpuid_init(void)
 out_class:
 	i = 0;
 	for_each_online_cpu(i) {
-		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, i));
+		cpuid_device_destroy(i);
 	}
 	class_destroy(cpuid_class);
 out_chrdev:
@@ -228,7 +234,7 @@ static void __exit cpuid_exit(void)
 	int cpu = 0;
 
 	for_each_online_cpu(cpu)
-		device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
+		cpuid_device_destroy(cpu);
 	class_destroy(cpuid_class);
 	unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
 	unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);