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Update the usage of pxCurrentTCB
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* Update the usage of pxCurrentTCB to improve multiple accessing
  volatile variable in a function
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@chinglee-iot
chinglee-iot committed May 20, 2024
1 parent d4b8bfd commit edfa323
Showing 1 changed file with 49 additions and 32 deletions.
81 changes: 49 additions & 32 deletions tasks.c
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Original file line number Diff line number Diff line change
Expand Up @@ -86,7 +86,7 @@

#define taskYIELD_ANY_CORE_IF_USING_PREEMPTION( pxTCB ) \
do { \
TCB_t * const pxConstCurrentTCB = prvGetCurrentTask(); \
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCB(); \
if( pxConstCurrentTCB->uxPriority < ( pxTCB )->uxPriority ) \
{ \
portYIELD_WITHIN_API(); \
Expand Down Expand Up @@ -220,7 +220,7 @@
#define taskSELECT_HIGHEST_PRIORITY_TASK() \
do { \
UBaseType_t uxTopPriority; \
TCB_t * const pxConstCurrentTCB = prvGetCurrentTask(); \
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCB(); \
\
/* Find the highest priority list that contains ready tasks. */ \
portGET_HIGHEST_PRIORITY( uxTopPriority, uxTopReadyPriority ); \
Expand Down Expand Up @@ -282,7 +282,7 @@
* task should be used in place of the parameter. This macro simply checks to
* see if the parameter is NULL and returns a pointer to the appropriate TCB.
*/
#define prvGetTCBFromHandle( pxHandle ) ( ( ( pxHandle ) == NULL ) ? prvGetCurrentTask() : ( pxHandle ) )
#define prvGetTCBFromHandle( pxHandle ) ( ( ( pxHandle ) == NULL ) ? prvGetCurrentTaskTCB() : ( pxHandle ) )

/* The item value of the event list item is normally used to hold the priority
* of the task to which it belongs (coded to allow it to be held in reverse
Expand Down Expand Up @@ -441,11 +441,17 @@ typedef struct tskTaskControlBlock /* The old naming convention is used to
* below to enable the use of older kernel aware debuggers. */
typedef tskTCB TCB_t;

#if configNUMBER_OF_CORES == 1
#define prvGetCurrentTaskImmutable() pxCurrentTCB
#define prvGetCurrentTask() pxCurrentTCB
/* Retrieving the current task TCB in a multi-core environment involves two steps:
* 1. Obtaining the core ID.
* 2. Using the core ID to index the pxCurrentTCBs array.
* If these two steps are not performed atomically, a race condition may occur.
* To ensure atomicity, prvGetCurrentTaskTCBUnsafe() should be called in a context where
* the core executing the task remains fixed until the operation is completed. */
#if ( configNUMBER_OF_CORES == 1 )
#define prvGetCurrentTaskTCBUnsafe() pxCurrentTCB
#define prvGetCurrentTaskTCB() pxCurrentTCB
#else
#define prvGetCurrentTaskImmutable() pxCurrentTCBs[ portGET_CORE_ID() ]
#define prvGetCurrentTaskTCBUnsafe() pxCurrentTCBs[ portGET_CORE_ID() ]
#endif

#if ( configNUMBER_OF_CORES == 1 )
Expand Down Expand Up @@ -541,6 +547,15 @@ static BaseType_t prvCreateIdleTasks( void );

#if ( configNUMBER_OF_CORES > 1 )

/*
* The race condition safe version to get the current task TCB in multiple cores
* environment.
*/
static TCB_t * prvGetCurrentTaskTCB( void );
#endif /* #if ( configNUMBER_OF_CORES > 1 ) */

#if ( configNUMBER_OF_CORES > 1 )

/*
* Checks to see if another task moved the current task out of the ready
* list while it was waiting to enter a critical section and yields, if so.
Expand Down Expand Up @@ -811,7 +826,7 @@ static void prvAddNewTaskToReadyList( TCB_t * pxNewTCB ) PRIVILEGED_FUNCTION;

#if ( configNUMBER_OF_CORES > 1 )

static TCB_t * prvGetCurrentTask( void )
static TCB_t * prvGetCurrentTaskTCB( void )
{
TCB_t * pxTCB;
UBaseType_t uxSavedInterruptStatus;
Expand All @@ -826,6 +841,8 @@ static void prvAddNewTaskToReadyList( TCB_t * pxNewTCB ) PRIVILEGED_FUNCTION;
}
#endif /* if ( configNUMBER_OF_CORES > 1 ) */

/*-----------------------------------------------------------*/

#if ( configNUMBER_OF_CORES > 1 )
static void prvCheckForRunStateChange( void )
{
Expand Down Expand Up @@ -2793,7 +2810,7 @@ static void prvInitialiseNewTask( TaskFunction_t pxTaskCode,
TCB_t * pxTCB;
UBaseType_t uxCurrentBasePriority, uxPriorityUsedOnEntry;
BaseType_t xYieldRequired = pdFALSE;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTask();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCB();

#if ( configNUMBER_OF_CORES > 1 )
BaseType_t xYieldForTask = pdFALSE;
Expand Down Expand Up @@ -3442,7 +3459,7 @@ static void prvInitialiseNewTask( TaskFunction_t pxTaskCode,
BaseType_t xYieldRequired = pdFALSE;
TCB_t * const pxTCB = xTaskToResume;
UBaseType_t uxSavedInterruptStatus;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_xTaskResumeFromISR( xTaskToResume );

Expand Down Expand Up @@ -3738,7 +3755,7 @@ void vTaskStartScheduler( void )

#if ( configUSE_C_RUNTIME_TLS_SUPPORT == 1 )
{
TCB_t * const pxConstCurrentTCB = prvGetCurrentTask();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCB();

/* Switch C-Runtime's TLS Block to point to the TLS
* block specific to the task that will run first. */
Expand Down Expand Up @@ -3924,7 +3941,7 @@ void vTaskSuspendAll( void )
{
TickType_t xReturn;
UBaseType_t uxHigherPriorityReadyTasks = pdFALSE;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTask();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCB();

/* uxHigherPriorityReadyTasks takes care of the case where
* configUSE_PREEMPTION is 0, so there may be tasks above the idle priority
Expand Down Expand Up @@ -4002,7 +4019,7 @@ BaseType_t xTaskResumeAll( void )
taskENTER_CRITICAL();
{
BaseType_t xCoreID;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

xCoreID = ( BaseType_t ) portGET_CORE_ID();

Expand Down Expand Up @@ -4658,7 +4675,7 @@ BaseType_t xTaskCatchUpTicks( TickType_t xTicksToCatchUp )
{
#if ( configNUMBER_OF_CORES == 1 )
{
TCB_t * const pxCurrentTCB = prvGetCurrentTask();
TCB_t * const pxCurrentTCB = prvGetCurrentTaskTCB();

/* Preemption is on, but a context switch should only be
* performed if the unblocked task has a priority that is
Expand Down Expand Up @@ -4706,7 +4723,7 @@ BaseType_t xTaskIncrementTick( void )
TCB_t * pxTCB;
TickType_t xItemValue;
BaseType_t xSwitchRequired = pdFALSE;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

#if ( configUSE_PREEMPTION == 1 ) && ( configNUMBER_OF_CORES > 1 )
BaseType_t xYieldRequiredForCore[ configNUMBER_OF_CORES ] = { pdFALSE };
Expand Down Expand Up @@ -5264,7 +5281,7 @@ BaseType_t xTaskIncrementTick( void )
void vTaskPlaceOnEventList( List_t * const pxEventList,
const TickType_t xTicksToWait )
{
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_vTaskPlaceOnEventList( pxEventList, xTicksToWait );

Expand Down Expand Up @@ -5296,7 +5313,7 @@ void vTaskPlaceOnUnorderedEventList( List_t * pxEventList,
const TickType_t xItemValue,
const TickType_t xTicksToWait )
{
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_vTaskPlaceOnUnorderedEventList( pxEventList, xItemValue, xTicksToWait );

Expand Down Expand Up @@ -5330,7 +5347,7 @@ void vTaskPlaceOnUnorderedEventList( List_t * pxEventList,
TickType_t xTicksToWait,
const BaseType_t xWaitIndefinitely )
{
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_vTaskPlaceOnEventListRestricted( pxEventList, xTicksToWait, xWaitIndefinitely );

Expand Down Expand Up @@ -5370,7 +5387,7 @@ BaseType_t xTaskRemoveFromEventList( const List_t * const pxEventList )
TCB_t * pxUnblockedTCB;
BaseType_t xReturn;

TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_xTaskRemoveFromEventList( pxEventList );

Expand Down Expand Up @@ -5464,7 +5481,7 @@ void vTaskRemoveFromUnorderedEventList( ListItem_t * pxEventListItem,
const TickType_t xItemValue )
{
TCB_t * pxUnblockedTCB;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_vTaskRemoveFromUnorderedEventList( pxEventListItem, xItemValue );

Expand Down Expand Up @@ -5567,7 +5584,7 @@ BaseType_t xTaskCheckForTimeOut( TimeOut_t * const pxTimeOut,
BaseType_t xReturn;

#if ( INCLUDE_xTaskAbortDelay == 1 )
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();
#endif

traceENTER_xTaskCheckForTimeOut( pxTimeOut, pxTicksToWait );
Expand Down Expand Up @@ -6522,7 +6539,7 @@ static void prvResetNextTaskUnblockTime( void )

/* In SMP environment, interrupt must be disabled to get the current
* task TCB. */
xReturn = prvGetCurrentTask();
xReturn = prvGetCurrentTaskTCB();

traceRETURN_xTaskGetCurrentTaskHandle( xReturn );

Expand Down Expand Up @@ -6599,7 +6616,7 @@ static void prvResetNextTaskUnblockTime( void )
TCB_t * const pxMutexHolderTCB = pxMutexHolder;
BaseType_t xReturn = pdFALSE;

TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_xTaskPriorityInherit( pxMutexHolder );

Expand Down Expand Up @@ -6946,7 +6963,7 @@ static void prvResetNextTaskUnblockTime( void )

if( xSchedulerRunning != pdFALSE )
{
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

( pxConstCurrentTCB->uxCriticalNesting )++;

Expand Down Expand Up @@ -7058,7 +7075,7 @@ static void prvResetNextTaskUnblockTime( void )

void vTaskExitCritical( void )
{
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_vTaskExitCritical();

Expand Down Expand Up @@ -7593,7 +7610,7 @@ TickType_t uxTaskResetEventItemValue( void )
{
TickType_t uxReturn;

TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_uxTaskResetEventItemValue();

Expand All @@ -7618,7 +7635,7 @@ TickType_t uxTaskResetEventItemValue( void )
traceENTER_pvTaskIncrementMutexHeldCount();

/* This API should be called in critical section only. */
pxTCB = prvGetCurrentTaskImmutable();
pxTCB = prvGetCurrentTaskTCBUnsafe();

/* If xSemaphoreCreateMutex() is called before any tasks have been created
* then pxCurrentTCB will be NULL. */
Expand All @@ -7643,7 +7660,7 @@ TickType_t uxTaskResetEventItemValue( void )
{
uint32_t ulReturn;
BaseType_t xAlreadyYielded, xShouldBlock = pdFALSE;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTask();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCB();

traceENTER_ulTaskGenericNotifyTake( uxIndexToWaitOn, xClearCountOnExit, xTicksToWait );

Expand Down Expand Up @@ -7748,7 +7765,7 @@ TickType_t uxTaskResetEventItemValue( void )
TickType_t xTicksToWait )
{
BaseType_t xReturn, xAlreadyYielded, xShouldBlock = pdFALSE;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTask();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCB();

traceENTER_xTaskGenericNotifyWait( uxIndexToWaitOn, ulBitsToClearOnEntry, ulBitsToClearOnExit, pulNotificationValue, xTicksToWait );

Expand Down Expand Up @@ -7988,7 +8005,7 @@ TickType_t uxTaskResetEventItemValue( void )
uint8_t ucOriginalNotifyState;
BaseType_t xReturn = pdPASS;
UBaseType_t uxSavedInterruptStatus;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_xTaskGenericNotifyFromISR( xTaskToNotify, uxIndexToNotify, ulValue, eAction, pulPreviousNotificationValue, pxHigherPriorityTaskWoken );

Expand Down Expand Up @@ -8151,7 +8168,7 @@ TickType_t uxTaskResetEventItemValue( void )
TCB_t * pxTCB;
uint8_t ucOriginalNotifyState;
UBaseType_t uxSavedInterruptStatus;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

traceENTER_vTaskGenericNotifyGiveFromISR( xTaskToNotify, uxIndexToNotify, pxHigherPriorityTaskWoken );

Expand Down Expand Up @@ -8449,7 +8466,7 @@ static void prvAddCurrentTaskToDelayedList( TickType_t xTicksToWait,
const TickType_t xConstTickCount = xTickCount;
List_t * const pxDelayedList = pxDelayedTaskList;
List_t * const pxOverflowDelayedList = pxOverflowDelayedTaskList;
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskImmutable();
TCB_t * const pxConstCurrentTCB = prvGetCurrentTaskTCBUnsafe();

#if ( INCLUDE_xTaskAbortDelay == 1 )
{
Expand Down

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