412 lines
16 KiB
C
412 lines
16 KiB
C
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/*
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* FreeRTOS V202212.00
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* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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/*
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* The tasks defined on this page demonstrate the use of recursive mutexes.
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*
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* For recursive mutex functionality the created mutex should be created using
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* xSemaphoreCreateRecursiveMutex(), then be manipulated
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* using the xSemaphoreTakeRecursive() and xSemaphoreGiveRecursive() API
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* functions.
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*
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* This demo creates three tasks all of which access the same recursive mutex:
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*
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* prvRecursiveMutexControllingTask() has the highest priority so executes
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* first and grabs the mutex. It then performs some recursive accesses -
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* between each of which it sleeps for a short period to let the lower
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* priority tasks execute. When it has completed its demo functionality
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* it gives the mutex back before suspending itself.
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*
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* prvRecursiveMutexBlockingTask() attempts to access the mutex by performing
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* a blocking 'take'. The blocking task has a lower priority than the
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* controlling task so by the time it executes the mutex has already been
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* taken by the controlling task, causing the blocking task to block. It
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* does not unblock until the controlling task has given the mutex back,
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* and it does not actually run until the controlling task has suspended
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* itself (due to the relative priorities). When it eventually does obtain
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* the mutex all it does is give the mutex back prior to also suspending
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* itself. At this point both the controlling task and the blocking task are
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* suspended.
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*
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* prvRecursiveMutexPollingTask() runs at the idle priority. It spins round
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* a tight loop attempting to obtain the mutex with a non-blocking call. As
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* the lowest priority task it will not successfully obtain the mutex until
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* both the controlling and blocking tasks are suspended. Once it eventually
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* does obtain the mutex it first unsuspends both the controlling task and
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* blocking task prior to giving the mutex back - resulting in the polling
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* task temporarily inheriting the controlling tasks priority.
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*/
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/* Scheduler include files. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "semphr.h"
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/* Demo app include files. */
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#include "recmutex.h"
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/* Priorities assigned to the three tasks. recmuCONTROLLING_TASK_PRIORITY can
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* be overridden by a definition in FreeRTOSConfig.h. */
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#ifndef recmuCONTROLLING_TASK_PRIORITY
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#define recmuCONTROLLING_TASK_PRIORITY ( tskIDLE_PRIORITY + 2 )
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#endif
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#define recmuBLOCKING_TASK_PRIORITY ( tskIDLE_PRIORITY + 1 )
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#define recmuPOLLING_TASK_PRIORITY ( tskIDLE_PRIORITY + 0 )
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/* The recursive call depth. */
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#define recmuMAX_COUNT ( 10 )
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/* Misc. */
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#define recmuSHORT_DELAY ( pdMS_TO_TICKS( 20 ) )
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#define recmuNO_DELAY ( ( TickType_t ) 0 )
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#define recmu15ms_DELAY ( pdMS_TO_TICKS( 15 ) )
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#ifndef recmuRECURSIVE_MUTEX_TEST_TASK_STACK_SIZE
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#define recmuRECURSIVE_MUTEX_TEST_TASK_STACK_SIZE configMINIMAL_STACK_SIZE
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#endif
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/* The three tasks as described at the top of this file. */
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static void prvRecursiveMutexControllingTask( void * pvParameters );
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static void prvRecursiveMutexBlockingTask( void * pvParameters );
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static void prvRecursiveMutexPollingTask( void * pvParameters );
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/* The mutex used by the demo. */
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static SemaphoreHandle_t xMutex;
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/* Variables used to detect and latch errors. */
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static volatile BaseType_t xErrorOccurred = pdFALSE, xControllingIsSuspended = pdFALSE, xBlockingIsSuspended = pdFALSE;
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static volatile UBaseType_t uxControllingCycles = 0, uxBlockingCycles = 0, uxPollingCycles = 0;
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/* Handles of the two higher priority tasks, required so they can be resumed
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* (unsuspended). */
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static TaskHandle_t xControllingTaskHandle, xBlockingTaskHandle;
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/*-----------------------------------------------------------*/
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void vStartRecursiveMutexTasks( void )
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{
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/* Just creates the mutex and the three tasks. */
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xMutex = xSemaphoreCreateRecursiveMutex();
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if( xMutex != NULL )
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{
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/* vQueueAddToRegistry() adds the mutex to the registry, if one is
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* in use. The registry is provided as a means for kernel aware
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* debuggers to locate mutex and has no purpose if a kernel aware debugger
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* is not being used. The call to vQueueAddToRegistry() will be removed
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* by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is
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* defined to be less than 1. */
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vQueueAddToRegistry( ( QueueHandle_t ) xMutex, "Recursive_Mutex" );
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xTaskCreate( prvRecursiveMutexControllingTask, "Rec1", recmuRECURSIVE_MUTEX_TEST_TASK_STACK_SIZE, NULL, recmuCONTROLLING_TASK_PRIORITY, &xControllingTaskHandle );
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xTaskCreate( prvRecursiveMutexBlockingTask, "Rec2", recmuRECURSIVE_MUTEX_TEST_TASK_STACK_SIZE, NULL, recmuBLOCKING_TASK_PRIORITY, &xBlockingTaskHandle );
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xTaskCreate( prvRecursiveMutexPollingTask, "Rec3", recmuRECURSIVE_MUTEX_TEST_TASK_STACK_SIZE, NULL, recmuPOLLING_TASK_PRIORITY, NULL );
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}
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}
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/*-----------------------------------------------------------*/
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static void prvRecursiveMutexControllingTask( void * pvParameters )
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{
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UBaseType_t ux;
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/* Just to remove compiler warning. */
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( void ) pvParameters;
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for( ; ; )
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{
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/* Should not be able to 'give' the mutex, as we have not yet 'taken'
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* it. The first time through, the mutex will not have been used yet,
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* subsequent times through, at this point the mutex will be held by the
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* polling task. */
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if( xSemaphoreGiveRecursive( xMutex ) == pdPASS )
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{
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xErrorOccurred = __LINE__;
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}
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for( ux = 0; ux < recmuMAX_COUNT; ux++ )
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{
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/* We should now be able to take the mutex as many times as
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* we like.
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*
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* The first time through the mutex will be immediately available, on
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* subsequent times through the mutex will be held by the polling task
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* at this point and this Take will cause the polling task to inherit
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* the priority of this task. In this case the block time must be
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* long enough to ensure the polling task will execute again before the
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* block time expires. If the block time does expire then the error
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* flag will be set here. */
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if( xSemaphoreTakeRecursive( xMutex, recmu15ms_DELAY ) != pdPASS )
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{
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xErrorOccurred = __LINE__;
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}
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/* Ensure the other task attempting to access the mutex (and the
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* other demo tasks) are able to execute to ensure they either block
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* (where a block time is specified) or return an error (where no
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* block time is specified) as the mutex is held by this task. */
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vTaskDelay( recmuSHORT_DELAY );
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}
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/* For each time we took the mutex, give it back. */
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for( ux = 0; ux < recmuMAX_COUNT; ux++ )
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{
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/* Ensure the other task attempting to access the mutex (and the
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* other demo tasks) are able to execute. */
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vTaskDelay( recmuSHORT_DELAY );
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/* We should now be able to give the mutex as many times as we
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* took it. When the mutex is available again the Blocking task
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* should be unblocked but not run because it has a lower priority
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* than this task. The polling task should also not run at this point
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* as it too has a lower priority than this task. */
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if( xSemaphoreGiveRecursive( xMutex ) != pdPASS )
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{
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xErrorOccurred = __LINE__;
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}
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#if ( configUSE_PREEMPTION == 0 )
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taskYIELD();
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#endif
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}
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/* Having given it back the same number of times as it was taken, we
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* should no longer be the mutex owner, so the next give should fail. */
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if( xSemaphoreGiveRecursive( xMutex ) == pdPASS )
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{
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xErrorOccurred = __LINE__;
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}
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/* Keep count of the number of cycles this task has performed so a
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* stall can be detected. */
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uxControllingCycles++;
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/* Suspend ourselves so the blocking task can execute. */
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xControllingIsSuspended = pdTRUE;
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vTaskSuspend( NULL );
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xControllingIsSuspended = pdFALSE;
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}
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}
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/*-----------------------------------------------------------*/
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static void prvRecursiveMutexBlockingTask( void * pvParameters )
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{
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/* Just to remove compiler warning. */
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( void ) pvParameters;
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for( ; ; )
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{
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/* This task will run while the controlling task is blocked, and the
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* controlling task will block only once it has the mutex - therefore
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* this call should block until the controlling task has given up the
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* mutex, and not actually execute past this call until the controlling
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* task is suspended. portMAX_DELAY - 1 is used instead of portMAX_DELAY
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* to ensure the task's state is reported as Blocked and not Suspended in
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* a later call to configASSERT() (within the polling task). */
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if( xSemaphoreTakeRecursive( xMutex, ( portMAX_DELAY - 1 ) ) == pdPASS )
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{
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if( xControllingIsSuspended != pdTRUE )
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{
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/* Did not expect to execute until the controlling task was
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* suspended. */
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xErrorOccurred = __LINE__;
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}
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else
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{
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/* Give the mutex back before suspending ourselves to allow
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* the polling task to obtain the mutex. */
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if( xSemaphoreGiveRecursive( xMutex ) != pdPASS )
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{
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xErrorOccurred = __LINE__;
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}
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xBlockingIsSuspended = pdTRUE;
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vTaskSuspend( NULL );
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xBlockingIsSuspended = pdFALSE;
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}
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}
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else
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{
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/* We should not leave the xSemaphoreTakeRecursive() function
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* until the mutex was obtained. */
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xErrorOccurred = __LINE__;
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}
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/* The controlling and blocking tasks should be in lock step. */
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if( uxControllingCycles != ( UBaseType_t ) ( uxBlockingCycles + 1 ) )
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{
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xErrorOccurred = __LINE__;
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}
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/* Keep count of the number of cycles this task has performed so a
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* stall can be detected. */
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uxBlockingCycles++;
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}
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}
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/*-----------------------------------------------------------*/
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static void prvRecursiveMutexPollingTask( void * pvParameters )
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{
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/* Just to remove compiler warning. */
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( void ) pvParameters;
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for( ; ; )
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{
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/* Keep attempting to obtain the mutex. It should only be obtained when
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* the blocking task has suspended itself, which in turn should only
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* happen when the controlling task is also suspended. */
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if( xSemaphoreTakeRecursive( xMutex, recmuNO_DELAY ) == pdPASS )
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{
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#if ( INCLUDE_eTaskGetState == 1 )
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{
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configASSERT( eTaskGetState( xControllingTaskHandle ) == eSuspended );
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configASSERT( eTaskGetState( xBlockingTaskHandle ) == eSuspended );
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}
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#endif /* INCLUDE_eTaskGetState */
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/* Is the blocking task suspended? */
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if( ( xBlockingIsSuspended != pdTRUE ) || ( xControllingIsSuspended != pdTRUE ) )
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{
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xErrorOccurred = __LINE__;
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}
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else
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{
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/* Keep count of the number of cycles this task has performed
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* so a stall can be detected. */
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uxPollingCycles++;
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/* We can resume the other tasks here even though they have a
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* higher priority than the polling task. When they execute they
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* will attempt to obtain the mutex but fail because the polling
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* task is still the mutex holder. The polling task (this task)
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* will then inherit the higher priority. The Blocking task will
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* block indefinitely when it attempts to obtain the mutex, the
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* Controlling task will only block for a fixed period and an
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* error will be latched if the polling task has not returned the
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* mutex by the time this fixed period has expired. */
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vTaskResume( xBlockingTaskHandle );
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#if ( configUSE_PREEMPTION == 0 )
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taskYIELD();
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#endif
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vTaskResume( xControllingTaskHandle );
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#if ( configUSE_PREEMPTION == 0 )
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taskYIELD();
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#endif
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/* The other two tasks should now have executed and no longer
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* be suspended. */
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if( ( xBlockingIsSuspended == pdTRUE ) || ( xControllingIsSuspended == pdTRUE ) )
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{
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xErrorOccurred = __LINE__;
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}
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#if ( INCLUDE_uxTaskPriorityGet == 1 )
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{
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/* Check priority inherited. */
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configASSERT( uxTaskPriorityGet( NULL ) == recmuCONTROLLING_TASK_PRIORITY );
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}
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#endif /* INCLUDE_uxTaskPriorityGet */
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#if ( INCLUDE_eTaskGetState == 1 )
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{
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configASSERT( eTaskGetState( xControllingTaskHandle ) == eBlocked );
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configASSERT( eTaskGetState( xBlockingTaskHandle ) == eBlocked );
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}
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#endif /* INCLUDE_eTaskGetState */
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/* Release the mutex, disinheriting the higher priority again. */
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if( xSemaphoreGiveRecursive( xMutex ) != pdPASS )
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{
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xErrorOccurred = __LINE__;
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}
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#if ( INCLUDE_uxTaskPriorityGet == 1 )
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{
|
||
|
|
/* Check priority disinherited. */
|
||
|
|
configASSERT( uxTaskPriorityGet( NULL ) == recmuPOLLING_TASK_PRIORITY );
|
||
|
|
}
|
||
|
|
#endif /* INCLUDE_uxTaskPriorityGet */
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#if configUSE_PREEMPTION == 0
|
||
|
|
{
|
||
|
|
taskYIELD();
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
}
|
||
|
|
}
|
||
|
|
/*-----------------------------------------------------------*/
|
||
|
|
|
||
|
|
/* This is called to check that all the created tasks are still running. */
|
||
|
|
BaseType_t xAreRecursiveMutexTasksStillRunning( void )
|
||
|
|
{
|
||
|
|
BaseType_t xReturn;
|
||
|
|
static UBaseType_t uxLastControllingCycles = 0, uxLastBlockingCycles = 0, uxLastPollingCycles = 0;
|
||
|
|
|
||
|
|
/* Is the controlling task still cycling? */
|
||
|
|
if( uxLastControllingCycles == uxControllingCycles )
|
||
|
|
{
|
||
|
|
xErrorOccurred = __LINE__;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
uxLastControllingCycles = uxControllingCycles;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Is the blocking task still cycling? */
|
||
|
|
if( uxLastBlockingCycles == uxBlockingCycles )
|
||
|
|
{
|
||
|
|
xErrorOccurred = __LINE__;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
uxLastBlockingCycles = uxBlockingCycles;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Is the polling task still cycling? */
|
||
|
|
if( uxLastPollingCycles == uxPollingCycles )
|
||
|
|
{
|
||
|
|
xErrorOccurred = __LINE__;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
uxLastPollingCycles = uxPollingCycles;
|
||
|
|
}
|
||
|
|
|
||
|
|
if( xErrorOccurred != pdFALSE )
|
||
|
|
{
|
||
|
|
xReturn = pdFAIL;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
xReturn = pdPASS;
|
||
|
|
}
|
||
|
|
|
||
|
|
return xReturn;
|
||
|
|
}
|