modify rt_thread_resume for necessary schedule judgment

src/thread.c

@@ -875,13 +875,16 @@ RTM_EXPORT(rt_thread_suspend);
  *
  * @param thread is the thread to be resumed.
  *
- * @return Return the operation status. If the return value is RT_EOK, the function is successfully executed.
- * If the return value is any other values, it means this operation failed.
+ * @return Return the operation status.
+ * When the return value is RT_EOK, the new ready thread have highest priority, need to schedule immediately
+ * When the return value is RT_EBUSY, although have readied the thread but its priority is not the highest.
+ * If the return value is any other values, it means this operation failed.
  */
 rt_err_t rt_thread_resume(rt_thread_t thread)
 {
  rt_base_t level;
-
+ rt_err_t result = RT_EOK;
+ extern rt_uint8_t rt_current_priority;
  /* parameter check */
  RT_ASSERT(thread != RT_NULL);
  RT_ASSERT(rt_object_get_type((rt_object_t)thread) == RT_Object_Class_Thread);
@@ -907,11 +910,21 @@ rt_err_t rt_thread_resume(rt_thread_t thread)
  /* insert to schedule ready list */
  rt_schedule_insert_thread(thread);
 
+ /* compare the priority with rt_current_priority*/
+ if(thread->current_priority < rt_current_priority)
+ {
+ result == RT_EOK;
+ }
+ else
+ {
+ result == RT_EBUSY;
+ }
+
  /* enable interrupt */
  rt_hw_interrupt_enable(level);
 
  RT_OBJECT_HOOK_CALL(rt_thread_resume_hook, (thread));
- return RT_EOK;
+ return result;
 }
 RTM_EXPORT(rt_thread_resume);