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FreeRTOS: Modifying a timeout is now protected on multi-core configuration

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This commit is contained in:
Omar Chebib 2022-07-27 11:40:34 +08:00
parent b823831a26
commit 692891e773
1 changed files with 25 additions and 4 deletions
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21
components/freertos/FreeRTOS-Kernel/tasks.c
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@ -3941,9 +3941,30 @@ void vTaskSetTimeOutState( TimeOut_t * const pxTimeOut )
void vTaskInternalSetTimeOutState( TimeOut_t * const pxTimeOut )
{
/**
* In case of we are building for SMP, we need to protect the following instructions in order to make them
* atomic.
* Indeed, without this, it would be possible to get preempted by the tick hook right after storing the number
* of overflows with `pxTimeOut->xOverflowCount = xNumOfOverflows`. Then, the tick hook increments the timer,
* which overflows, and thus resets the xTickCount to 0.
* Resuming our task would result in an invalid state of the timer where the number of overflow corresponds
* to the previous value and not the current one.
*
* On a single core configuration, this problem doesn't appear as this function is meant to be called from
* a critical section, disabling the (tick) interrupts.
*/
#if ( ( ESP_PLATFORM == 1 ) && ( configNUM_CORES > 1 ) )
configASSERT( pxTimeOut );
taskENTER_CRITICAL();
#endif // ( ( ESP_PLATFORM == 1 ) && ( configNUM_CORES > 1 ) )
/* For internal use only as it does not use a critical section. */
pxTimeOut->xOverflowCount = xNumOfOverflows;
pxTimeOut->xTimeOnEntering = xTickCount;
#if ( ( ESP_PLATFORM == 1 ) && ( configNUM_CORES > 1 ) )
taskEXIT_CRITICAL();
#endif // ( ( ESP_PLATFORM == 1 ) && ( configNUM_CORES > 1 ) )
}
/*-----------------------------------------------------------*/