Kernel changes:

Minor change to xQueueGenericReceive() to catch the extreme case of data being placed into a queue between a task timing out and leaving the xQueueGenericReceive() function.
Added xSemaphoreGetCount() macro.


Demo app changes:
Updated countsem.c to test the new xSemaphoreGetCount() macro.

FreeRTOS/Demo/Common/Minimal/countsem.c

@@ -68,7 +68,7 @@
 */
 
 
-/* 
+/*
  * Simple demonstration of the usage of counting semaphore.
  */
 
@@ -84,7 +84,7 @@
 #define countMAX_COUNT_VALUE	( 200 )
 
 /* Constants used to indicate whether or not the semaphore should have been
-created with its maximum count value, or its minimum count value.  These 
+created with its maximum count value, or its minimum count value.  These
 numbers are used to ensure that the pointers passed in as the task parameters
 are valid. */
 #define countSTART_AT_MAX_COUNT	( 0xaa )
@@ -118,7 +118,7 @@ static void prvCountingSemaphoreTask( void *pvParameters );
 static void prvIncrementSemaphoreCount( SemaphoreHandle_t xSemaphore, UBaseType_t *puxLoopCounter );
 
 /*
- * Utility function to decrement the semaphore count value up from 
+ * Utility function to decrement the semaphore count value up from
  * countMAX_COUNT_VALUE to zero.
  */
 static void prvDecrementSemaphoreCount( SemaphoreHandle_t xSemaphore, UBaseType_t *puxLoopCounter );
@@ -134,11 +134,11 @@ typedef struct COUNT_SEM_STRUCT
 	/* Set to countSTART_AT_MAX_COUNT if the semaphore should be created with
 	its count value set to its max count value, or countSTART_AT_ZERO if it
 	should have been created with its count value set to 0. */
-	UBaseType_t uxExpectedStartCount;	
+	UBaseType_t uxExpectedStartCount;
 
 	/* Incremented on each cycle of the demo task.  Used to detect a stalled
 	task. */
-	UBaseType_t uxLoopCounter;			
+	UBaseType_t uxLoopCounter;
 } xCountSemStruct;
 
 /* Two structures are defined, one is passed to each test task. */
@@ -160,10 +160,10 @@ void vStartCountingSemaphoreTasks( void )
 	xParameters[ 1 ].uxLoopCounter = 0;
 
 	/* vQueueAddToRegistry() adds the semaphore to the registry, if one is
-	in use.  The registry is provided as a means for kernel aware 
+	in use.  The registry is provided as a means for kernel aware
 	debuggers to locate semaphores and has no purpose if a kernel aware debugger
 	is not being used.  The call to vQueueAddToRegistry() will be removed
-	by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is 
+	by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
 	defined to be less than 1. */
 	vQueueAddToRegistry( ( QueueHandle_t ) xParameters[ 0 ].xSemaphore, "Counting_Sem_1" );
 	vQueueAddToRegistry( ( QueueHandle_t ) xParameters[ 1 ].xSemaphore, "Counting_Sem_2" );
@@ -174,7 +174,7 @@ void vStartCountingSemaphoreTasks( void )
 	{
 		/* Create the demo tasks, passing in the semaphore to use as the parameter. */
 		xTaskCreate( prvCountingSemaphoreTask, "CNT1", configMINIMAL_STACK_SIZE, ( void * ) &( xParameters[ 0 ] ), tskIDLE_PRIORITY, NULL );
-		xTaskCreate( prvCountingSemaphoreTask, "CNT2", configMINIMAL_STACK_SIZE, ( void * ) &( xParameters[ 1 ] ), tskIDLE_PRIORITY, NULL );		
+		xTaskCreate( prvCountingSemaphoreTask, "CNT2", configMINIMAL_STACK_SIZE, ( void * ) &( xParameters[ 1 ] ), tskIDLE_PRIORITY, NULL );
 	}
 }
 /*-----------------------------------------------------------*/
@@ -193,6 +193,8 @@ UBaseType_t ux;
 	/* We should be able to 'take' the semaphore countMAX_COUNT_VALUE times. */
 	for( ux = 0; ux < countMAX_COUNT_VALUE; ux++ )
 	{
+		configASSERT( xSemaphoreGetCount( xSemaphore ) == ( countMAX_COUNT_VALUE - ux ) );
+
 		if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) != pdPASS )
 		{
 			/* We expected to be able to take the semaphore. */
@@ -206,8 +208,9 @@ UBaseType_t ux;
 		taskYIELD();
 	#endif
 
-	/* If the semaphore count is zero then we should not be able to	'take' 
+	/* If the semaphore count is zero then we should not be able to	'take'
 	the semaphore. */
+	configASSERT( xSemaphoreGetCount( xSemaphore ) == 0 );
 	if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) == pdPASS )
 	{
 		xErrorDetected = pdTRUE;
@@ -219,7 +222,7 @@ static void prvIncrementSemaphoreCount( SemaphoreHandle_t xSemaphore, UBaseType_
 {
 UBaseType_t ux;
 
-	/* If the semaphore count is zero then we should not be able to	'take' 
+	/* If the semaphore count is zero then we should not be able to	'take'
 	the semaphore. */
 	if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) == pdPASS )
 	{
@@ -229,6 +232,8 @@ UBaseType_t ux;
 	/* We should be able to 'give' the semaphore countMAX_COUNT_VALUE times. */
 	for( ux = 0; ux < countMAX_COUNT_VALUE; ux++ )
 	{
+		configASSERT( xSemaphoreGetCount( xSemaphore ) == ux );
+
 		if( xSemaphoreGive( xSemaphore ) != pdPASS )
 		{
 			/* We expected to be able to take the semaphore. */
@@ -257,7 +262,7 @@ xCountSemStruct *pxParameter;
 
 	#ifdef USE_STDIO
 	void vPrintDisplayMessage( const char * const * ppcMessageToSend );
-	
+
 		const char * const pcTaskStartMsg = "Counting semaphore demo started.\r\n";
 
 		/* Queue a message for printing to say the task has started. */

FreeRTOS/Source/include/FreeRTOS.h

@@ -776,6 +776,10 @@ extern "C" {
 	#define configSUPPORT_STATIC_ALLOCATION 0
 #endif
 
+#if( ( configUSE_RECURSIVE_MUTEXES == 1 ) && ( configUSE_MUTEXES != 1 ) )
+    #error configUSE_MUTEXES must be set to 1 to use recursive mutexes
+#endif 
+
 #if( portTICK_TYPE_IS_ATOMIC == 0 )
 	/* Either variables of tick type cannot be read atomically, or
 	portTICK_TYPE_IS_ATOMIC was not set - map the critical sections used when

FreeRTOS/Source/include/semphr.h

@@ -839,6 +839,18 @@ typedef QueueHandle_t SemaphoreHandle_t;
  */
 #define xSemaphoreGetMutexHolder( xSemaphore ) xQueueGetMutexHolder( ( xSemaphore ) )
 
+/**
+ * semphr.h
+ * <pre>TaskHandle_t xSemaphoreGetCount( SemaphoreHandle_t xMutex );</pre>
+ *
+ * If the semaphore is a counting semaphore then xSemaphoreGetCount() returns
+ * its current count value.  If the semaphore is a binary semaphore then
+ * xSemaphoreGetCount() returns 1 if the semaphore is available, and 0 if the
+ * semaphore is not available.
+ *
+ */
+#define xSemaphoreGetCount( xSemaphore ) uxQueueMessagesWaiting( ( QueueHandle_t ) ( xSemaphore ) )
+
 #endif /* SEMAPHORE_H */
 
 

FreeRTOS/Source/queue.c

@@ -797,8 +797,6 @@ Queue_t * const pxQueue = ( Queue_t * ) xQueue;
 			prvUnlockQueue( pxQueue );
 			( void ) xTaskResumeAll();
 
-			/* Return to the original privilege level before exiting the
-			function. */
 			traceQUEUE_SEND_FAILED( pxQueue );
 			return errQUEUE_FULL;
 		}
@@ -1385,7 +1383,7 @@ Queue_t * const pxQueue = ( Queue_t * ) xQueue;
 		taskENTER_CRITICAL();
 		{
 			/* Is there data in the queue now?  To be running the calling task
-			must be	the highest priority task wanting to access the queue. */
+			must be the highest priority task wanting to access the queue. */
 			if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
 			{
 				/* Remember the read position in case the queue is only being
@@ -1541,8 +1539,16 @@ Queue_t * const pxQueue = ( Queue_t * ) xQueue;
 		{
 			prvUnlockQueue( pxQueue );
 			( void ) xTaskResumeAll();
-			traceQUEUE_RECEIVE_FAILED( pxQueue );
+
-			return errQUEUE_EMPTY;
+			if( prvIsQueueEmpty( pxQueue ) != pdFALSE )
+			{
+				traceQUEUE_RECEIVE_FAILED( pxQueue );
+				return errQUEUE_EMPTY;
+			}
+			else
+			{
+				mtCOVERAGE_TEST_MARKER();
+			}
 		}
 	}
 }

FreeRTOS/Source/tasks.c

@@ -1618,7 +1618,7 @@ uint16_t usIdleTaskStackSize = tskIDLE_STACK_SIZE;
 		configASSERT( xReturn );
 	}
 
-	/* Prevent compiler warnings if INCLUDE_xTaskGetIdleTaskHandle is set to 0, 
+	/* Prevent compiler warnings if INCLUDE_xTaskGetIdleTaskHandle is set to 0,
 	meaning xIdleTaskHandle is not used anywhere else. */
 	( void ) xIdleTaskHandle;
 }
@@ -2732,9 +2732,13 @@ static portTASK_FUNCTION( prvIdleTask, pvParameters )
 	/* Stop warnings. */
 	( void ) pvParameters;
 
+	/** THIS IS THE RTOS IDLE TASK - WHICH IS CREATED AUTOMATICALLY WHEN THE
+	SCHEDULER IS STARTED. **/
+
 	for( ;; )
 	{
-		/* See if any tasks have been deleted. */
+		/* See if any tasks have deleted themselves - if so then the idle task
+		is responsible for freeing the deleted task's TCB and stack. */
 		prvCheckTasksWaitingTermination();
 
 		#if ( configUSE_PREEMPTION == 0 )
@@ -3029,7 +3033,7 @@ UBaseType_t x;
 		the calling task. */
 		pxTCB = prvGetTCBFromHandle( xTaskToModify );
 
-        vPortStoreTaskMPUSettings( &( pxTCB->xMPUSettings ), xRegions, NULL, 0 );
+		vPortStoreTaskMPUSettings( &( pxTCB->xMPUSettings ), xRegions, NULL, 0 );
 	}
 
 #endif /* portUSING_MPU_WRAPPERS */
@@ -3069,6 +3073,9 @@ UBaseType_t uxPriority;
 
 static void prvCheckTasksWaitingTermination( void )
 {
+
+	/** THIS FUNCTION IS CALLED FROM  THE RTOS IDLE TASK **/
+
 	#if ( INCLUDE_vTaskDelete == 1 )
 	{
 		BaseType_t xListIsEmpty;