Implementation of mutex held counting in tasks.c - needs optimisation before release.

FreeRTOS/Source/tasks.c

@@ -146,6 +146,7 @@ typedef struct tskTaskControlBlock
 
 	#if ( configUSE_MUTEXES == 1 )
 		UBaseType_t 	uxBasePriority;		/*< The priority last assigned to the task - used by the priority inheritance mechanism. */
+		UBaseType_t 	uxMutexesHeld;
 	#endif
 
 	#if ( configUSE_APPLICATION_TASK_TAG == 1 )
@@ -2737,6 +2738,7 @@ UBaseType_t x;
 	#if ( configUSE_MUTEXES == 1 )
 	{
 		pxTCB->uxBasePriority = uxPriority;
+		pxTCB->uxMutexesHeld = 0;
 	}
 	#endif /* configUSE_MUTEXES */
 
@@ -3235,16 +3237,20 @@ TCB_t *pxTCB;
 
 #if ( configUSE_MUTEXES == 1 )
 
-	void vTaskPriorityDisinherit( TaskHandle_t const pxMutexHolder )
+	BaseType_t xTaskPriorityDisinherit( TaskHandle_t const pxMutexHolder )
 	{
 	TCB_t * const pxTCB = ( TCB_t * ) pxMutexHolder;
+	BaseType_t xReturn = pdFALSE;
 
 		if( pxMutexHolder != NULL )
 		{
 			if( pxTCB->uxPriority != pxTCB->uxBasePriority )
 			{
-				/* We must be the running task to be able to give the mutex back.
+				/* Only disinherit if no other mutexes are held. */
-				Remove ourselves from the ready list we currently appear in. */
+				if( pxTCB->uxMutexesHeld == 0 )
+				{
+					/* The holding task must be the running task to be able to give
+					the mutex back.  Remove the holding task from the ready list. */
 					if( uxListRemove( &( pxTCB->xGenericListItem ) ) == ( UBaseType_t ) 0 )
 					{
 						taskRESET_READY_PRIORITY( pxTCB->uxPriority );
@@ -3267,9 +3273,16 @@ TCB_t *pxTCB;
 					}
 					else
 					{
+#warning Is it possible to come through here?
 						mtCOVERAGE_TEST_MARKER();
 					}
 					prvAddTaskToReadyList( pxTCB );
+
+					/* Return true to indicate that a context switch is required.
+					This is only actually required in the corner case whereby
+					multiple mutexes were held and the mutexes were given back
+					in an order different to that in which they were taken. */
+					xReturn = pdTRUE;
 				}
 				else
 				{
@@ -3281,6 +3294,13 @@ TCB_t *pxTCB;
 				mtCOVERAGE_TEST_MARKER();
 			}
 		}
+		else
+		{
+			mtCOVERAGE_TEST_MARKER();
+		}
+
+		return xReturn;
+	}
 
 #endif /* configUSE_MUTEXES */
 /*-----------------------------------------------------------*/
@@ -3294,6 +3314,18 @@ TCB_t *pxTCB;
 		if( xSchedulerRunning != pdFALSE )
 		{
 			( pxCurrentTCB->uxCriticalNesting )++;
+
+			/* This is not the interrupt safe version of the enter critical
+			function so	assert() if it is being called from an interrupt
+			context.  Only API functions that end in "FromISR" can be used in an
+			interrupt.  Only assert if the critical nesting count is 1 to
+			protect against recursive calls if the assert function also uses a
+			critical section. */
+			if( pxCurrentTCB->uxCriticalNesting == 1 )
+			{
+				portASSERT_IF_IN_ISR();
+			}
+
 		}
 		else
 		{
@@ -3557,6 +3589,18 @@ TickType_t uxReturn;
 }
 /*-----------------------------------------------------------*/
 
+void vTaskIncrementMutexHeldCount( void )
+{
+	( pxCurrentTCB->uxMutexesHeld )++;
+}
+/*-----------------------------------------------------------*/
+
+void vTaskDecrementMutexHeldCount( void )
+{
+	configASSERT( pxCurrentTCB->uxMutexesHeld );
+	( pxCurrentTCB->uxMutexesHeld )--;
+}
+
 #ifdef FREERTOS_MODULE_TEST
 	#include "tasks_test_access_functions.h"
 #endif