void vTaskDelete( TaskHandle_t xTaskToDelete )
{
TCB_t * pxTCB;
BaseType_t xDeleteTCBInIdleTask = pdFALSE;
BaseType_t xTaskIsRunningOrYielding;
traceENTER_vTaskDelete( xTaskToDelete );
taskENTER_CRITICAL();
{
获取当前要删除任务的TCB，如果xTaskToDelete 为空则表示要删除当前正在运行的任务，否则就找到对应任务的TCB。
pxTCB = prvGetTCBFromHandle( xTaskToDelete );
configASSERT( pxTCB != NULL );
把当前要删除的任务从ready/delayed 链表中删除，并判断任务优先级的链表任务数是否为0
if( uxListRemove( &( pxTCB->xStateListItem ) ) == ( UBaseType_t ) 0 )
{
如果当前要删除的任务优先级所对应的链表任务数为0，则将该优先级在uxTopReadyPriority中mask掉。
taskRESET_READY_PRIORITY( pxTCB->uxPriority );
}
else
{
mtCOVERAGE_TEST_MARKER();
}
判断当前的任务是否在一个event的链表，如果是则通过uxListRemove将其移除
if( listLIST_ITEM_CONTAINER( &( pxTCB->xEventListItem ) ) != NULL )
{
( void ) uxListRemove( &( pxTCB->xEventListItem ) );
}
else
{
mtCOVERAGE_TEST_MARKER();
}
/* Increment the uxTaskNumber also so kernel aware debuggers can
* detect that the task lists need re-generating. This is done before
* portPRE_TASK_DELETE_HOOK() as in the Windows port that macro will
* not return. */
uxTaskNumber++;
通过taskTASK_IS_RUNNING_OR_SCHEDULED_TO_YIELD来判断当前的任务是否在运行状态，如果其xTaskRunState被设置为-1则表明其不处于运行状态，正常运行的任务其xTaskRunState值会被设置为所运行的core的id。
xTaskIsRunningOrYielding = taskTASK_IS_RUNNING_OR_SCHEDULED_TO_YIELD( pxTCB );
根据xSchedulerRunning 来判断当前的是否还处于正常的调度状态，该全局变量在vTaskStartScheduler函数被执行时设置为pdTRUE，在vTaskEndScheduler时被设置为pdFALSE
if( ( xSchedulerRunning != pdFALSE ) && ( xTaskIsRunningOrYielding != pdFALSE ) )
{
为了防止该任务在其他core上还有运行的，所以将该任务添加到xTasksWaitingTermination链表上，等idle task运行时再做清理工作。
vListInsertEnd( &xTasksWaitingTermination, &( pxTCB->xStateListItem ) );
标记当前需要做清理的任务数
++uxDeletedTasksWaitingCleanUp;
/* Call the delete hook before portPRE_TASK_DELETE_HOOK() as
* portPRE_TASK_DELETE_HOOK() does not return in the Win32 port. */
traceTASK_DELETE( pxTCB );
用以标记有任务需要删除，如果需要设置为pdTRUE，则在后面会调用prvDeleteTCB( pxTCB );释放掉这块内存空间。
xDeleteTCBInIdleTask = pdTRUE;
/* The pre-delete hook is primarily for the Windows simulator,
* in which Windows specific clean up operations are performed,
* after which it is not possible to yield away from this task -
* hence xYieldPending is used to latch that a context switch is
* required. */
#if ( configNUMBER_OF_CORES == 1 )
portPRE_TASK_DELETE_HOOK( pxTCB, &( xYieldPendings[ 0 ] ) );
#else
portPRE_TASK_DELETE_HOOK( pxTCB, &( xYieldPendings[ pxTCB->xTaskRunState ] ) );
#endif
在SMP系统给按任务让出CPU，让其他任务去运行
#if ( configNUMBER_OF_CORES > 1 )
{
if( taskTASK_IS_RUNNING( pxTCB ) == pdTRUE )
{
if( pxTCB->xTaskRunState == ( BaseType_t ) portGET_CORE_ID() )
{
configASSERT( uxSchedulerSuspended == 0 );
taskYIELD_WITHIN_API();
}
else
{
prvYieldCore( pxTCB->xTaskRunState );
}
}
}
#endif /* #if ( configNUMBER_OF_CORES > 1 ) */
}
else
{
--uxCurrentNumberOfTasks;
traceTASK_DELETE( pxTCB );
/* Reset the next expected unblock time in case it referred to
* the task that has just been deleted. */
prvResetNextTaskUnblockTime();
}
}
taskEXIT_CRITICAL();
/* If the task is not deleting itself, call prvDeleteTCB from outside of
* critical section. If a task deletes itself, prvDeleteTCB is called
* from prvCheckTasksWaitingTermination which is called from Idle task. */
if( xDeleteTCBInIdleTask != pdTRUE )
{
prvDeleteTCB( pxTCB );
}
/* Force a reschedule if it is the currently running task that has just
* been deleted. */
#if ( configNUMBER_OF_CORES == 1 )
{
if( xSchedulerRunning != pdFALSE )
{
if( pxTCB == pxCurrentTCB )
{
configASSERT( uxSchedulerSuspended == 0 );
taskYIELD_WITHIN_API();
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
}
#endif /* #if ( configNUMBER_OF_CORES == 1 ) */
traceRETURN_vTaskDelete();
}
UBaseType_t uxListRemove( ListItem_t * const pxItemToRemove )
{
/* The list item knows which list it is in. Obtain the list from the list
* item. */
List_t * const pxList = pxItemToRemove->pxContainer;
traceENTER_uxListRemove( pxItemToRemove );
pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
/* Only used during decision coverage testing. */
mtCOVERAGE_TEST_DELAY();
/* Make sure the index is left pointing to a valid item. */
if( pxList->pxIndex == pxItemToRemove )
{
pxList->pxIndex = pxItemToRemove->pxPrevious;
}
else
{
mtCOVERAGE_TEST_MARKER();
}
pxItemToRemove->pxContainer = NULL;
( pxList->uxNumberOfItems ) = ( UBaseType_t ) ( pxList->uxNumberOfItems - 1U );
traceRETURN_uxListRemove( pxList->uxNumberOfItems );
return pxList->uxNumberOfItems;
}