2 files changed, 66 insertions, 2 deletions

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 03e235ad1bba..488d6ebcf6a1 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -122,26 +122,46 @@ enum {
                 { .notifier_call = fn, .priority = pri };       \
         register_cpu_notifier(&fn##_nb);                        \
 }
+
+#define __cpu_notifier(fn, pri) {                               \
+        static struct notifier_block fn##_nb =                  \
+                { .notifier_call = fn, .priority = pri };       \
+        __register_cpu_notifier(&fn##_nb);                      \
+}
 #else /* #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE) */
 #define cpu_notifier(fn, pri)   do { (void)(fn); } while (0)
+#define __cpu_notifier(fn, pri) do { (void)(fn); } while (0)
 #endif /* #else #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE) */
+
 #ifdef CONFIG_HOTPLUG_CPU
 extern int register_cpu_notifier(struct notifier_block *nb);
+extern int __register_cpu_notifier(struct notifier_block *nb);
 extern void unregister_cpu_notifier(struct notifier_block *nb);
+extern void __unregister_cpu_notifier(struct notifier_block *nb);
 #else
 
 #ifndef MODULE
 extern int register_cpu_notifier(struct notifier_block *nb);
+extern int __register_cpu_notifier(struct notifier_block *nb);
 #else
 static inline int register_cpu_notifier(struct notifier_block *nb)
 {
         return 0;
 }
+
+static inline int __register_cpu_notifier(struct notifier_block *nb)
+{
+        return 0;
+}
 #endif
 
 static inline void unregister_cpu_notifier(struct notifier_block *nb)
 {
 }
+
+static inline void __unregister_cpu_notifier(struct notifier_block *nb)
+{
+}
 #endif
 
 int cpu_up(unsigned int cpu);
@@ -149,19 +169,32 @@ void notify_cpu_starting(unsigned int cpu);
 extern void cpu_maps_update_begin(void);
 extern void cpu_maps_update_done(void);
 
+#define cpu_notifier_register_begin     cpu_maps_update_begin
+#define cpu_notifier_register_done      cpu_maps_update_done
+
 #else   /* CONFIG_SMP */
 
 #define cpu_notifier(fn, pri)   do { (void)(fn); } while (0)
+#define __cpu_notifier(fn, pri) do { (void)(fn); } while (0)
 
 static inline int register_cpu_notifier(struct notifier_block *nb)
 {
         return 0;
 }
 
+static inline int __register_cpu_notifier(struct notifier_block *nb)
+{
+        return 0;
+}
+
 static inline void unregister_cpu_notifier(struct notifier_block *nb)
 {
 }
 
+static inline void __unregister_cpu_notifier(struct notifier_block *nb)
+{
+}
+
 static inline void cpu_maps_update_begin(void)
 {
 }
@@ -170,6 +203,14 @@ static inline void cpu_maps_update_done(void)
 {
 }
 
+static inline void cpu_notifier_register_begin(void)
+{
+}
+
+static inline void cpu_notifier_register_done(void)
+{
+}
+
 #endif /* CONFIG_SMP */
 extern struct bus_type cpu_subsys;
 
@@ -183,8 +224,11 @@ extern void put_online_cpus(void);
 extern void cpu_hotplug_disable(void);
 extern void cpu_hotplug_enable(void);
 #define hotcpu_notifier(fn, pri)        cpu_notifier(fn, pri)
+#define __hotcpu_notifier(fn, pri)      __cpu_notifier(fn, pri)
 #define register_hotcpu_notifier(nb)    register_cpu_notifier(nb)
+#define __register_hotcpu_notifier(nb)  __register_cpu_notifier(nb)
 #define unregister_hotcpu_notifier(nb)  unregister_cpu_notifier(nb)
+#define __unregister_hotcpu_notifier(nb)        __unregister_cpu_notifier(nb)
 void clear_tasks_mm_cpumask(int cpu);
 int cpu_down(unsigned int cpu);
 
@@ -197,9 +241,12 @@ static inline void cpu_hotplug_done(void) {}
 #define cpu_hotplug_disable()   do { } while (0)
 #define cpu_hotplug_enable()    do { } while (0)
 #define hotcpu_notifier(fn, pri)        do { (void)(fn); } while (0)
+#define __hotcpu_notifier(fn, pri)      do { (void)(fn); } while (0)
 /* These aren't inline functions due to a GCC bug. */
 #define register_hotcpu_notifier(nb)    ({ (void)(nb); 0; })
+#define __register_hotcpu_notifier(nb)  ({ (void)(nb); 0; })
 #define unregister_hotcpu_notifier(nb)  ({ (void)(nb); })
+#define __unregister_hotcpu_notifier(nb)        ({ (void)(nb); })
 #endif          /* CONFIG_HOTPLUG_CPU */
 
 #ifdef CONFIG_PM_SLEEP_SMP
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 33caf5e97701..a9e710eef0e2 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -28,18 +28,23 @@
 static DEFINE_MUTEX(cpu_add_remove_lock);
 
 /*
- * The following two API's must be used when attempting
- * to serialize the updates to cpu_online_mask, cpu_present_mask.
+ * The following two APIs (cpu_maps_update_begin/done) must be used when
+ * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
+ * The APIs cpu_notifier_register_begin/done() must be used to protect CPU
+ * hotplug callback (un)registration performed using __register_cpu_notifier()
+ * or __unregister_cpu_notifier().
  */
 void cpu_maps_update_begin(void)
 {
         mutex_lock(&cpu_add_remove_lock);
 }
+EXPORT_SYMBOL(cpu_notifier_register_begin);
 
 void cpu_maps_update_done(void)
 {
         mutex_unlock(&cpu_add_remove_lock);
 }
+EXPORT_SYMBOL(cpu_notifier_register_done);
 
 static RAW_NOTIFIER_HEAD(cpu_chain);
 
@@ -183,6 +188,11 @@ int __ref register_cpu_notifier(struct notifier_block *nb)
         return ret;
 }
 
+int __ref __register_cpu_notifier(struct notifier_block *nb)
+{
+        return raw_notifier_chain_register(&cpu_chain, nb);
+}
+
 static int __cpu_notify(unsigned long val, void *v, int nr_to_call,
                         int *nr_calls)
 {
@@ -206,6 +216,7 @@ static void cpu_notify_nofail(unsigned long val, void *v)
         BUG_ON(cpu_notify(val, v));
 }
 EXPORT_SYMBOL(register_cpu_notifier);
+EXPORT_SYMBOL(__register_cpu_notifier);
 
 void __ref unregister_cpu_notifier(struct notifier_block *nb)
 {
@@ -215,6 +226,12 @@ void __ref unregister_cpu_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_cpu_notifier);
 
+void __ref __unregister_cpu_notifier(struct notifier_block *nb)
+{
+        raw_notifier_chain_unregister(&cpu_chain, nb);
+}
+EXPORT_SYMBOL(__unregister_cpu_notifier);
+
 /**
  * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
  * @cpu: a CPU id