cpu hotplug: mce: fix cpu hotplug error handling

- Clear kobject in percpu device_mce before calling sysdev_register() with

  Because mce_create_device() may fail and it leaves kobject filled with
  junk. It will be the problem when mce_create_device() will be called
  next time.

- Fix error handling in mce_create_device()

  Error handling should not do sysdev_remove_file() with not yet added
  attributes.

- Don't register hotcpu notifier when mce_create_device() returns error

- Do mce_create_device() in CPU_UP_PREPARE instead of CPU_ONLINE

Cc: Andi Kleen <andi@firstfloor.org>
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, 29 insertions, 10 deletions

diff --git a/arch/x86/kernel/mce_64.c b/arch/x86/kernel/mce_64.c
index 8ca8f8648969..66e6b797b2cb 100644
--- a/arch/x86/kernel/mce_64.c
+++ b/arch/x86/kernel/mce_64.c
@@ -802,16 +802,29 @@ static __cpuinit int mce_create_device(unsigned int cpu)
         if (!mce_available(&cpu_data[cpu]))
                 return -EIO;
 
+        memset(&per_cpu(device_mce, cpu).kobj, 0, sizeof(struct kobject));
         per_cpu(device_mce,cpu).id = cpu;
         per_cpu(device_mce,cpu).cls = &mce_sysclass;
 
         err = sysdev_register(&per_cpu(device_mce,cpu));
+        if (err)
+                return err;
+
+        for (i = 0; mce_attributes[i]; i++) {
+                err = sysdev_create_file(&per_cpu(device_mce,cpu),
+                                         mce_attributes[i]);
+                if (err)
+                        goto error;
+        }
 
-        if (!err) {
-                for (i = 0; mce_attributes[i]; i++)
-                        sysdev_create_file(&per_cpu(device_mce,cpu),
-                                mce_attributes[i]);
+        return 0;
+error:
+        while (i--) {
+                sysdev_remove_file(&per_cpu(device_mce,cpu),
+                                   mce_attributes[i]);
         }
+        sysdev_unregister(&per_cpu(device_mce,cpu));
+
         return err;
 }
 
@@ -823,7 +836,6 @@ static void mce_remove_device(unsigned int cpu)
                 sysdev_remove_file(&per_cpu(device_mce,cpu),
                         mce_attributes[i]);
         sysdev_unregister(&per_cpu(device_mce,cpu));
-        memset(&per_cpu(device_mce, cpu).kobj, 0, sizeof(struct kobject));
 }
 
 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
@@ -831,18 +843,21 @@ static int
 mce_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:
-                mce_create_device(cpu);
+        case CPU_UP_PREPARE:
+        case CPU_UP_PREPARE_FROZEN:
+                err = mce_create_device(cpu);
                 break;
+        case CPU_UP_CANCELED:
+        case CPU_UP_CANCELED_FROZEN:
         case CPU_DEAD:
         case CPU_DEAD_FROZEN:
                 mce_remove_device(cpu);
                 break;
         }
-        return NOTIFY_OK;
+        return err ? NOTIFY_BAD : NOTIFY_OK;
 }
 
 static struct notifier_block mce_cpu_notifier = {
@@ -857,9 +872,13 @@ static __init int mce_init_device(void)
         if (!mce_available(&boot_cpu_data))
                 return -EIO;
         err = sysdev_class_register(&mce_sysclass);
+        if (err)
+                return err;
 
         for_each_online_cpu(i) {
-                mce_create_device(i);
+                err = mce_create_device(i);
+                if (err)
+                        return err;
         }
 
         register_hotcpu_notifier(&mce_cpu_notifier);