Delete kernel created task in vTaskEndScheduler (#962)

* Update vTaskDelete() to delete a task directly when scheduler is stopped instead of putting it on the xTasksWaitingTermination list.
* Delete the idle tasks and timer task in vTaskEndScheduler().
* Reclaim resources for all the tasks on the xTasksWaitingTermination list in vTaskEndScheduler().
* Update POSIX to no longer delete FreeRTOS tasks in the port.

---------

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>
Co-authored-by: Gaurav Aggarwal <aggarg@amazon.com>

portable/ThirdParty/GCC/Posix/port.c

@@ -74,7 +74,6 @@
 /* Scheduler includes. */
 #include "FreeRTOS.h"
 #include "task.h"
-#include "list.h"
 #include "timers.h"
 #include "utils/wait_for_event.h"
 /*-----------------------------------------------------------*/
@@ -88,7 +87,6 @@ typedef struct THREAD
     void * pvParams;
     BaseType_t xDying;
     struct event * ev;
-    ListItem_t xThreadListItem;
 } Thread_t;
 
 /*
@@ -113,7 +111,6 @@ static BaseType_t xSchedulerEnd = pdFALSE;
 static pthread_t hTimerTickThread;
 static bool xTimerTickThreadShouldRun;
 static uint64_t prvStartTimeNs;
-static List_t xThreadList;
 /*-----------------------------------------------------------*/
 
 static void prvSetupSignalsAndSchedulerPolicy( void );
@@ -197,14 +194,8 @@ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
 
     thread->ev = event_create();
 
-    vListInitialiseItem( &thread->xThreadListItem );
-    listSET_LIST_ITEM_OWNER( &thread->xThreadListItem, thread );
-
     vPortEnterCritical();
 
-    /* Add the new thread in xThreadList. */
-    vListInsertEnd( &xThreadList, &thread->xThreadListItem );
-
     iRet = pthread_create( &thread->pthread, &xThreadAttributes,
                            prvWaitForStart, thread );
 
@@ -235,8 +226,6 @@ BaseType_t xPortStartScheduler( void )
 {
     int iSignal;
     sigset_t xSignals;
-    ListItem_t * pxIterator;
-    const ListItem_t * pxEndMarker;
 
     hMainThread = pthread_self();
     prvPortSetCurrentThreadName("Scheduler");
@@ -263,19 +252,6 @@ BaseType_t xPortStartScheduler( void )
         sigwait( &xSignals, &iSignal );
     }
 
-    /* Cancel all the running thread. */
-    pxEndMarker = listGET_END_MARKER( &xThreadList );
-
-    for( pxIterator = listGET_HEAD_ENTRY( &xThreadList ); pxIterator != pxEndMarker; pxIterator = listGET_NEXT( pxIterator ) )
-    {
-        Thread_t * pxThread = ( Thread_t * ) listGET_LIST_ITEM_OWNER( pxIterator );
-
-        pthread_cancel( pxThread->pthread );
-        event_signal( pxThread->ev );
-        pthread_join( pxThread->pthread, NULL );
-        event_delete( pxThread->ev );
-    }
-
     /*
      * clear out the variable that is used to end the scheduler, otherwise
      * subsequent scheduler restarts will end immediately.
@@ -300,6 +276,8 @@ BaseType_t xPortStartScheduler( void )
 
 void vPortEndScheduler( void )
 {
+    Thread_t * pxCurrentThread;
+
     /* Stop the timer tick thread. */
     xTimerTickThreadShouldRun = false;
     pthread_join( hTimerTickThread, NULL );
@@ -308,7 +286,10 @@ void vPortEndScheduler( void )
     xSchedulerEnd = pdTRUE;
     ( void ) pthread_kill( hMainThread, SIG_RESUME );
 
-    pthread_exit( NULL );
+    /* Waiting to be deleted here. */
+    pxCurrentThread = prvGetThreadFromTask( xTaskGetCurrentTaskHandle() );
+    event_wait( pxCurrentThread->ev );
+    pthread_testcancel();
 }
 /*-----------------------------------------------------------*/
 
@@ -491,11 +472,6 @@ void vPortCancelThread( void * pxTaskToDelete )
 {
     Thread_t * pxThreadToCancel = prvGetThreadFromTask( pxTaskToDelete );
 
-    /* Remove the thread from xThreadList. */
-    vPortEnterCritical();
-    uxListRemove( &pxThreadToCancel->xThreadListItem );
-    vPortExitCritical();
-
     /*
      * The thread has already been suspended so it can be safely cancelled.
      */
@@ -600,9 +576,6 @@ static void prvSetupSignalsAndSchedulerPolicy( void )
 
     hMainThread = pthread_self();
 
-    /* Setup thread list to record all the task which are not deleted. */
-    vListInitialise( &xThreadList );
-
     /* Initialise common signal masks. */
     sigfillset( &xAllSignals );
 

tasks.c

@@ -2229,7 +2229,7 @@ static void prvInitialiseNewTask( TaskFunction_t pxTaskCode,
             /* If the task is running (or yielding), we must add it to the
              * termination list so that an idle task can delete it when it is
              * no longer running. */
-            if( taskTASK_IS_RUNNING_OR_SCHEDULED_TO_YIELD( pxTCB ) != pdFALSE )
+            if( ( xSchedulerRunning != pdFALSE ) && ( taskTASK_IS_RUNNING_OR_SCHEDULED_TO_YIELD( pxTCB ) != pdFALSE ) )
             {
                 /* A running task or a task which is scheduled to yield is being
                  * deleted. This cannot complete when the task is still running
@@ -3740,11 +3740,39 @@ void vTaskEndScheduler( void )
 {
     traceENTER_vTaskEndScheduler();
 
+    #if ( INCLUDE_vTaskDelete == 1 )
+    {
+        BaseType_t xCoreID;
+
+        #if ( configUSE_TIMERS == 1 )
+        {
+            /* Delete the timer task created by the kernel. */
+            vTaskDelete( xTimerGetTimerDaemonTaskHandle() );
+        }
+        #endif /* #if ( configUSE_TIMERS == 1 ) */
+
+        /* Delete Idle tasks created by the kernel.*/
+        for( xCoreID = 0; xCoreID < ( BaseType_t ) configNUMBER_OF_CORES; xCoreID++ )
+        {
+            vTaskDelete( xIdleTaskHandles[ xCoreID ] );
+        }
+
+        /* Idle task is responsible for reclaiming the resources of the tasks in
+         * xTasksWaitingTermination list. Since the idle task is now deleted and
+         * no longer going to run, we need to reclaim resources of all the tasks
+         * in the xTasksWaitingTermination list. */
+        prvCheckTasksWaitingTermination();
+    }
+    #endif /* #if ( INCLUDE_vTaskDelete == 1 ) */
+
     /* Stop the scheduler interrupts and call the portable scheduler end
      * routine so the original ISRs can be restored if necessary.  The port
      * layer must ensure interrupts enable  bit is left in the correct state. */
     portDISABLE_INTERRUPTS();
     xSchedulerRunning = pdFALSE;
+
+    /* This function must be called from a task and the application is
+     * responsible for deleting that task after the scheduler is stopped. */
     vPortEndScheduler();
 
     traceRETURN_vTaskEndScheduler();