Function prvCheckForRunStateChange

tasks.c:614–687

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

static void prvCheckForRunStateChange( void )
{
    UBaseType_t uxPrevCriticalNesting;
    UBaseType_t uxPrevSchedulerSuspended;
    TCB_t * pxThisTCB;

    /* This should be skipped when entering a critical section within
     * an ISR. If the task on the current core is no longer running, then
     * vTaskSwitchContext() probably should be run before returning, but
     * we don't have a way to force that to happen from here. */
    if( portCHECK_IF_IN_ISR() == pdFALSE )
    {
        /* This function is always called with interrupts disabled
         * so this is safe. */
        pxThisTCB = pxCurrentTCBs[ portGET_CORE_ID() ];

        while( pxThisTCB->xTaskRunState == taskTASK_YIELDING )
        {
            /* We are only here if we just entered a critical section
            * or if we just suspended the scheduler, and another task
            * has requested that we yield.
            *
            * This is slightly complicated since we need to save and restore
            * the suspension and critical nesting counts, as well as release
            * and reacquire the correct locks. And then do it all over again
            * if our state changed again during the reacquisition. */

            uxPrevCriticalNesting = pxThisTCB->uxCriticalNesting;
            uxPrevSchedulerSuspended = uxSchedulerSuspended;

            /* this must only be called the first time we enter into a critical
             * section, otherwise it could context switch in the middle of a
             * critical section. */
            configASSERT( uxPrevCriticalNesting + uxPrevSchedulerSuspended == 1U );

            uxSchedulerSuspended = 0U;

            if( uxPrevCriticalNesting > 0U )
            {
                pxThisTCB->uxCriticalNesting = 0U;
                portRELEASE_ISR_LOCK();
                portRELEASE_TASK_LOCK();
            }
            else
            {
                /* uxPrevSchedulerSuspended must be 1 */
                portRELEASE_TASK_LOCK();
            }

            portMEMORY_BARRIER();
            configASSERT( pxThisTCB->xTaskRunState == taskTASK_YIELDING );

            portENABLE_INTERRUPTS();

            /* Enabling interrupts should cause this core to immediately
             * service the pending interrupt and yield. If the run state is still
             * yielding here then that is a problem. */
            configASSERT( pxThisTCB->xTaskRunState != taskTASK_YIELDING );