Merge pull request #4432 from mysterywolf/mutex

[libc] remove inherent mutex protection

Author: BernardXiong

components/libc/compilers/armlibc/syscalls.c

@@ -13,7 +13,6 @@
  *                             RT_USING_DFS is not defined
  * 2020-02-13     Meco Man     re-implement exit() and abort()
  * 2020-02-14     Meco Man     implement _sys_tmpnam()
- * 2020-02-25     Meco Man     add multithreaded protection
  */
 
 #include <string.h>
@@ -42,36 +41,6 @@ const char __stdin_name[]  = "STDIN";
 const char __stdout_name[] = "STDOUT";
 const char __stderr_name[] = "STDERR";
 
-#ifdef RT_USING_HEAP
-int _mutex_initialize(rt_mutex_t *m)
-{
-    *m = rt_mutex_create("_mutex_", RT_IPC_FLAG_PRIO);
-    if(*m == RT_NULL)
-    {
-        return 0;
-    }
-    else
-    {
-        return 1;
-    }
-}
-
-void _mutex_acquire(rt_mutex_t *m)
-{
-    rt_mutex_take(*m, RT_WAITING_FOREVER);
-}
-
-void _mutex_release(rt_mutex_t *m)
-{
-    rt_mutex_release(*m);
-}
-
-void _mutex_free(rt_mutex_t *m)
-{
-    rt_mutex_delete(*m);
-}
-#endif
-
 /**
  * required by fopen() and freopen().
  *