解决yield操作不能及时释放cpu的问题

src/thread.c

@@ -478,7 +478,15 @@ RTM_EXPORT(rt_thread_delete);
  */
 rt_err_t rt_thread_yield(void)
 {
+    struct rt_thread *thread;
+    rt_base_t lock;
+
+    thread = rt_thread_self();
+    lock = rt_hw_interrupt_disable();
+    thread->remaining_tick = thread->init_tick;
+    thread->stat |= RT_THREAD_STAT_YIELD;
     rt_schedule();
+    rt_hw_interrupt_enable(lock);
 
     return RT_EOK;
 }