From: Gautham R Shenoy <ego@in.ibm.com>

Provide a common interface for all the subsystems to lock and unlock their
per-subsystem hotcpu mutexes.

When CONFIG_HOTPLUG_CPU is not set, these operations would be no-ops.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 include/linux/cpu.h |   15 +++++++++++++++
 1 files changed, 15 insertions(+)

diff -puN include/linux/cpu.h~handle-per-subsystem-mutexes-for-config_hotplug_cpu-not-set include/linux/cpu.h
--- a/include/linux/cpu.h~handle-per-subsystem-mutexes-for-config_hotplug_cpu-not-set
+++ a/include/linux/cpu.h
@@ -24,6 +24,7 @@
 #include <linux/compiler.h>
 #include <linux/cpumask.h>
 #include <asm/semaphore.h>
+#include <linux/mutex.h>
 
 struct cpu {
 	int node_id;		/* The node which contains the CPU */
@@ -74,6 +75,17 @@ extern struct sysdev_class cpu_sysdev_cl
 
 #ifdef CONFIG_HOTPLUG_CPU
 /* Stop CPUs going up and down. */
+
+static inline void cpuhotplug_mutex_lock(struct mutex *cpu_hp_mutex)
+{
+	mutex_lock(cpu_hp_mutex);
+}
+
+static inline void cpuhotplug_mutex_unlock(struct mutex *cpu_hp_mutex)
+{
+	mutex_unlock(cpu_hp_mutex);
+}
+
 extern void lock_cpu_hotplug(void);
 extern void unlock_cpu_hotplug(void);
 #define hotcpu_notifier(fn, pri) {				\
@@ -86,6 +98,9 @@ extern void unlock_cpu_hotplug(void);
 int cpu_down(unsigned int cpu);
 #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
 #else
+#define cpuhotplug_mutex_lock(m)	do { (void)(m); } while (0)
+#define cpuhotplug_mutex_unlock(m)	do { (void)(m); } while (0)
+
 #define lock_cpu_hotplug()	do { } while (0)
 #define unlock_cpu_hotplug()	do { } while (0)
 #define lock_cpu_hotplug_interruptible() 0
_