cpu hotplug: msr: fix cpu hotplug error handling

Do msr_device_create() in CPU_UP_PREPARE instead of CPU_ONLINE.

Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Andi Kleen <ak@suse.de>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 20 insertions, 15 deletions

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index df85c9c13601..e0d5e82e64b3 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -133,37 +133,42 @@ static const struct file_operations msr_fops = {
         .open = msr_open,
 };
 
-static int __cpuinit msr_device_create(int i)
+static int msr_device_create(int cpu)
 {
-        int err = 0;
         struct device *dev;
 
-        dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, i), "msr%d",i);
-        if (IS_ERR(dev))
-                err = PTR_ERR(dev);
-        return err;
+        dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu),
+                            "msr%d", cpu);
+        return IS_ERR(dev) ? PTR_ERR(dev) : 0;
+}
+
+static void msr_device_destroy(int cpu)
+{
+        device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
 }
 
 static int __cpuinit 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_ONLINE:
-        case CPU_ONLINE_FROZEN:
-                msr_device_create(cpu);
+        case CPU_UP_PREPARE:
+        case CPU_UP_PREPARE_FROZEN:
+                err = msr_device_create(cpu);
                 break;
+        case CPU_UP_CANCELED:
+        case CPU_UP_CANCELED_FROZEN:
         case CPU_DEAD:
         case CPU_DEAD_FROZEN:
-                device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
+                msr_device_destroy(cpu);
                 break;
         }
-        return NOTIFY_OK;
+        return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
-static struct notifier_block __cpuinitdata msr_class_cpu_notifier =
-{
+static struct notifier_block __cpuinitdata msr_class_cpu_notifier = {
         .notifier_call = msr_class_cpu_callback,
 };
 
@@ -196,7 +201,7 @@ static int __init msr_init(void)
 out_class:
         i = 0;
         for_each_online_cpu(i)
-                device_destroy(msr_class, MKDEV(MSR_MAJOR, i));
+                msr_device_destroy(i);
         class_destroy(msr_class);
 out_chrdev:
         unregister_chrdev(MSR_MAJOR, "cpu/msr");
@@ -208,7 +213,7 @@ static void __exit msr_exit(void)
 {
         int cpu = 0;
         for_each_online_cpu(cpu)
-                device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
+                msr_device_destroy(cpu);
         class_destroy(msr_class);
         unregister_chrdev(MSR_MAJOR, "cpu/msr");
         unregister_hotcpu_notifier(&msr_class_cpu_notifier);