diff --git a/include/rthw.h b/include/rthw.h
index a77f2c1e46..2a602dcfe7 100644
--- a/include/rthw.h
+++ b/include/rthw.h
@@ -143,10 +143,10 @@ typedef union {
     } tickets;
 } rt_hw_spinlock_t;
 
-typedef struct
+struct rt_spinlock
 {
     rt_hw_spinlock_t lock;
-} rt_spinlock_t;
+};
 
 void rt_hw_spin_lock_init(rt_hw_spinlock_t *lock);
 void rt_hw_spin_lock(rt_hw_spinlock_t *lock);
@@ -187,16 +187,8 @@ void rt_hw_secondary_cpu_idle_exec(void);
 #define rt_hw_spin_lock(lock)     *(lock) = rt_hw_interrupt_disable()
 #define rt_hw_spin_unlock(lock)   rt_hw_interrupt_enable(*(lock))
 
-typedef int rt_spinlock_t;
-
 #endif
 
-void rt_spin_lock_init(rt_spinlock_t *lock);
-void rt_spin_lock(rt_spinlock_t *lock);
-void rt_spin_unlock(rt_spinlock_t *lock);
-rt_base_t rt_spin_lock_irqsave(rt_spinlock_t *lock);
-void rt_spin_unlock_irqrestore(rt_spinlock_t *lock, rt_base_t level);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/rtthread.h b/include/rtthread.h
index d703f36268..13a1a4424b 100644
--- a/include/rtthread.h
+++ b/include/rtthread.h
@@ -391,6 +391,27 @@ rt_err_t rt_mq_recv(rt_mq_t    mq,
 rt_err_t rt_mq_control(rt_mq_t mq, int cmd, void *arg);
 #endif
 
+/*
+ * spinlock
+ */
+#ifdef RT_USING_SMP
+struct rt_spinlock;
+
+void rt_spin_lock_init(struct rt_spinlock *lock);
+void rt_spin_lock(struct rt_spinlock *lock);
+void rt_spin_unlock(struct rt_spinlock *lock);
+rt_base_t rt_spin_lock_irqsave(struct rt_spinlock *lock);
+void rt_spin_unlock_irqrestore(struct rt_spinlock *lock, rt_base_t level);
+
+#else
+#define rt_spin_lock_init(lock)                 /* nothing */
+#define rt_spin_lock(lock)                      rt_enter_critical()
+#define rt_spin_unlock(lock)                    rt_exit_critical()
+#define rt_spin_lock_irqsave(lock)              rt_hw_interrupt_disable()
+#define rt_spin_unlock_irqrestore(lock, level)  rt_hw_interrupt_enable(level)
+
+#endif
+
 /**@}*/
 
 #ifdef RT_USING_DEVICE
diff --git a/src/SConscript b/src/SConscript
index ea6e19318f..82c3b8aaf1 100644
--- a/src/SConscript
+++ b/src/SConscript
@@ -26,6 +26,9 @@ if GetDepend('RT_USING_MEMHEAP') == False:
 if GetDepend('RT_USING_DEVICE') == False:
     SrcRemove(src, ['device.c'])
 
+if GetDepend('RT_USING_SMP') == False:
+    SrcRemove(src, ['cpu.c'])
+
 group = DefineGroup('Kernel', src, depend = [''], CPPPATH = CPPPATH)
 
 Return('group')
diff --git a/src/cpu.c b/src/cpu.c
index a4075108e1..f6f210eda8 100644
--- a/src/cpu.c
+++ b/src/cpu.c
@@ -12,9 +12,12 @@
 #include <rthw.h>
 
 #ifdef RT_USING_SMP
-/***********************************
+static struct rt_cpu rt_cpus[RT_CPUS_NR];
+rt_hw_spinlock_t _cpus_lock;
+
+/*
  * disable scheduler
- ***********************************/
+ */
 static void rt_preempt_disable(void)
 {
 	register rt_base_t level;
@@ -23,7 +26,7 @@ static void rt_preempt_disable(void)
 	/* disable interrupt */
 	level = rt_hw_local_irq_disable();
 
-	current_thread = rt_cpu_self()->current_thread;
+	current_thread = rt_thread_self();
 	if (!current_thread)
 	{
 		rt_hw_local_irq_enable(level);
@@ -37,9 +40,9 @@ static void rt_preempt_disable(void)
 	rt_hw_local_irq_enable(level);
 }
 
-/***********************************
- * restore scheduler
- ***********************************/
+/*
+ * enable scheduler
+ */
 static void rt_preempt_enable(void)
 {
 	register rt_base_t level;
@@ -48,7 +51,7 @@ static void rt_preempt_enable(void)
 	/* disable interrupt */
 	level = rt_hw_local_irq_disable();
 
-	current_thread = rt_cpu_self()->current_thread;
+	current_thread = rt_thread_self();
 	if (!current_thread)
 	{
 		rt_hw_local_irq_enable(level);
@@ -62,73 +65,49 @@ static void rt_preempt_enable(void)
 	/* enable interrupt */
 	rt_hw_local_irq_enable(level);
 }
-#endif
 
-void rt_spin_lock_init(rt_spinlock_t *lock)
+void rt_spin_lock_init(struct rt_spinlock *lock)
 {
-#ifdef RT_USING_SMP
 	rt_hw_spin_lock_init(&lock->lock);
-#endif
 }
 RTM_EXPORT(rt_spin_lock_init)
 
-void rt_spin_lock(rt_spinlock_t *lock)
+void rt_spin_lock(struct rt_spinlock *lock)
 {
-#ifdef RT_USING_SMP
 	rt_preempt_disable();
 	rt_hw_spin_lock(&lock->lock);
-#else
-    rt_enter_critical();
-#endif
 }
 RTM_EXPORT(rt_spin_lock)
 
-void rt_spin_unlock(rt_spinlock_t *lock)
+void rt_spin_unlock(struct rt_spinlock *lock)
 {
-#ifdef RT_USING_SMP
 	rt_hw_spin_unlock(&lock->lock);
 	rt_preempt_enable();
-#else
-    rt_exit_critical();
-#endif
 }
 RTM_EXPORT(rt_spin_unlock)
 
-rt_base_t rt_spin_lock_irqsave(rt_spinlock_t *lock)
+rt_base_t rt_spin_lock_irqsave(struct rt_spinlock *lock)
 {
 	unsigned long level;
 
-#ifdef RT_USING_SMP
 	rt_preempt_disable();
 
 	level = rt_hw_local_irq_disable();
 	rt_hw_spin_lock(&lock->lock);
 
 	return level;
-#else
-    return rt_hw_interrupt_disable();
-#endif
 }
 RTM_EXPORT(rt_spin_lock_irqsave)
 
-void rt_spin_unlock_irqrestore(rt_spinlock_t *lock, rt_base_t level)
+void rt_spin_unlock_irqrestore(struct rt_spinlock *lock, rt_base_t level)
 {
-#ifdef RT_USING_SMP
 	rt_hw_spin_unlock(&lock->lock);
 	rt_hw_local_irq_enable(level);
 
 	rt_preempt_enable();
-#else
-    rt_hw_interrupt_enable(level);
-#endif
 }
 RTM_EXPORT(rt_spin_unlock_irqrestore)
 
-#ifdef RT_USING_SMP
-
-static struct rt_cpu rt_cpus[RT_CPUS_NR];
-rt_hw_spinlock_t _cpus_lock;
-
 /**
  * This fucntion will return current cpu.
  */
@@ -155,7 +134,7 @@ rt_base_t rt_cpus_lock(void)
     pcpu = rt_cpu_self();
     if (pcpu->current_thread != RT_NULL)
     {
-        register rt_uint16_t lock_nest = pcpu->current_thread->cpus_lock_nest;
+        register rt_ubase_t lock_nest = pcpu->current_thread->cpus_lock_nest;
 
         pcpu->current_thread->cpus_lock_nest++;
         if (lock_nest == 0)