rtos_idle_loop is MBED_NORETURN

Don't need loops at two layers.

Also tighten up slightly-invalid extern "C" markings.

Author: kjbracey

rtos/TARGET_CORTEX/mbed_rtx_handlers.c

@@ -22,6 +22,7 @@
 #include "mbed_interface.h"
 #include "RTX_Config.h"
 #include "rtos/rtos_handlers.h"
+#include "rtos/rtos_idle.h"
 
 #ifdef RTE_Compiler_EventRecorder
 #include "EventRecorder.h"              // Keil::Compiler:Event Recorder
@@ -30,8 +31,6 @@
 #define EvtRtxThreadTerminate          EventID(EventLevelAPI, 0xF2U, 0x1AU)
 #endif
 
-extern void rtos_idle_loop(void);
-
 static void (*terminate_hook)(osThreadId_t id);
 
 static void thread_terminate_hook(osThreadId_t id)
@@ -48,9 +47,7 @@ void rtos_attach_thread_terminate_hook(void (*fptr)(osThreadId_t id))
 
 __NO_RETURN void osRtxIdleThread(void *argument)
 {
-    for (;;) {
-        rtos_idle_loop();
-    }
+    rtos_idle_loop();
 }
 
 __NO_RETURN uint32_t osRtxErrorNotify(uint32_t code, void *object_id)

rtos/TARGET_CORTEX/mbed_rtx_idle.cpp

@@ -28,9 +28,10 @@
 #include "mbed_assert.h"
 #include <new>
 #include "rtx_os.h"
+
+/* Everything in rtx_lib.h, and provided by this file, has C linkage */
 extern "C" {
 #include "rtx_lib.h"
-}
 
 using namespace mbed;
 
@@ -136,10 +137,12 @@ void rtos_attach_idle_hook(void (*fptr)(void))
     }
 }
 
-extern "C" void rtos_idle_loop(void)
+MBED_NORETURN void rtos_idle_loop(void)
 {
     //Continuously call the idle hook function pointer
     while (1) {
         idle_hook_fptr();
     }
 }
+
+} // extern "C"

rtos/rtos_idle.h

@@ -25,6 +25,7 @@
 #ifndef RTOS_IDLE_H
 #define RTOS_IDLE_H
 
+#include "mbed_toolchain.h"
 #include <stddef.h>
 
 #ifdef __cplusplus
@@ -41,6 +42,10 @@ extern "C" {
  @param fptr Hook function pointer.
  */
 void rtos_attach_idle_hook(void (*fptr)(void));
+
+/** @private */
+MBED_NORETURN void rtos_idle_loop(void);
+
 /** @}*/
 
 #ifdef __cplusplus