Merge pull request #4703 from mysterywolf/mutexrevert

revert #3647

Author: BernardXiong

src/ipc.c

@@ -39,7 +39,6 @@
  * 2020-10-11     Meco Man     add value overflow-check code
  * 2021-01-03     Meco Man     implement rt_mb_urgent()
  * 2021-05-30     Meco Man     implement rt_mutex_trytake()
- * 2021-01-20     hupu         fix priority inversion bug of mutex
  */
 
 #include <rtthread.h>
@@ -194,31 +193,6 @@ rt_inline rt_err_t rt_ipc_list_resume_all(rt_list_t *list)
     return RT_EOK;
 }
 
-/**
- * This function will get the highest priority from the specified
- * list of threads
- *
- * @param list of the threads
- *
- * @return the highest priority
- */
-rt_uint8_t rt_ipc_get_highest_priority(rt_list_t *list)
-{
-    struct rt_list_node *n;
-    struct rt_thread *sthread;
-    rt_uint8_t priority = RT_THREAD_PRIORITY_MAX - 1;
-
-    for (n = list->next; n != list; n = n->next)
-    {
-        sthread = rt_list_entry(n, struct rt_thread, tlist);
-
-        priority = priority < sthread->current_priority ?
-                    priority :
-                    sthread->current_priority;
-    }
-    return priority;
-}
-
 #ifdef RT_USING_SEMAPHORE
 /**
  * This function will initialize a semaphore and put it under control of
@@ -870,7 +844,6 @@ rt_err_t rt_mutex_release(rt_mutex_t mutex)
     register rt_base_t temp;
     struct rt_thread *thread;
     rt_bool_t need_schedule;
-    rt_uint8_t max_priority_in_queue = RT_THREAD_PRIORITY_MAX - 1;
 
     /* parameter check */
     RT_ASSERT(mutex != RT_NULL);
@@ -932,21 +905,6 @@ rt_err_t rt_mutex_release(rt_mutex_t mutex)
             mutex->owner             = thread;
             mutex->original_priority = thread->current_priority;
 
-            /* Priority adjustment occurs only when the following conditions
-             * are met simultaneously:
-             * 1.The type of mutex is RT_IPC_FLAG_FIFO;
-             * 2.The priority of the thread to be resumed is not equal to the
-             *   highest priority in the queue;
-             */
-            max_priority_in_queue = rt_ipc_get_highest_priority(&mutex->parent.suspend_thread);
-            if (mutex->parent.parent.flag == RT_IPC_FLAG_FIFO &&
-                thread->current_priority != max_priority_in_queue)
-            {
-                rt_thread_control(thread,
-                        RT_THREAD_CTRL_CHANGE_PRIORITY,
-                        &(max_priority_in_queue));
-            }
-
             if(mutex->hold < RT_MUTEX_HOLD_MAX)
             {
                 mutex->hold ++;