About prvAddNewTaskToReadyList when the scheduler is suspended

Kernel
1

Hi folks:
I wonder why the prvAddNewTaskToReadyList only changed the pxCurrentTCB when a new task of equal or larger priority is added to ready list. I think we should also set xYieldPending to pdTRUE but why not? If we do not set xYieldPending , the pxCurrentTCB will not point to the correct task for a while until the next context switch occurs.

static void prvAddNewTaskToReadyList( TCB_t * pxNewTCB )
{
    /* Ensure interrupts don't access the task lists while the lists are being
     * updated. */
    taskENTER_CRITICAL();
    {
        uxCurrentNumberOfTasks++;

        if( pxCurrentTCB == NULL )
        {
            /* There are no other tasks, or all the other tasks are in
             * the suspended state - make this the current task. */
            pxCurrentTCB = pxNewTCB;

            if( uxCurrentNumberOfTasks == ( UBaseType_t ) 1 )
            {
                /* This is the first task to be created so do the preliminary
                 * initialisation required.  We will not recover if this call
                 * fails, but we will report the failure. */
                prvInitialiseTaskLists();
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }
        else
        {
            /* If the scheduler is not already running, make this task the
             * current task if it is the highest priority task to be created
             * so far. */
            if( xSchedulerRunning == pdFALSE )
            {
                if( pxCurrentTCB->uxPriority <= pxNewTCB->uxPriority )
                {
                    pxCurrentTCB = pxNewTCB;
                }
                else
                {
                    mtCOVERAGE_TEST_MARKER();
                }
            }
            else
            {
                mtCOVERAGE_TEST_MARKER();
            }
        }

        uxTaskNumber++;

        #if ( configUSE_TRACE_FACILITY == 1 )
            {
                /* Add a counter into the TCB for tracing only. */
                pxNewTCB->uxTCBNumber = uxTaskNumber;
            }
        #endif /* configUSE_TRACE_FACILITY */
        traceTASK_CREATE( pxNewTCB );

        prvAddTaskToReadyList( pxNewTCB );

        portSETUP_TCB( pxNewTCB );
    }
    taskEXIT_CRITICAL();

    if( xSchedulerRunning != pdFALSE )
    {
        /* If the created task is of a higher priority than the current task
         * then it should run now. */
        if( pxCurrentTCB->uxPriority < pxNewTCB->uxPriority )
        {
            taskYIELD_IF_USING_PREEMPTION();
        }
        else
        {
            mtCOVERAGE_TEST_MARKER();
        }
    }
    else
    {
        mtCOVERAGE_TEST_MARKER();
    }
}
2

Which path through the code are you referring to? There is nothing inside that function that checks if the scheduler is suspended because the function shouldn’t be called if it is. This line FreeRTOS-Kernel/tasks.c at V10.4.6 · FreeRTOS/FreeRTOS-Kernel · GitHub results in a context switch if necessary, so there is no need to set xYieldPending.

3

Thanks for the anwser, well, I found I confuse the xSchedulerRunning with uxSchedulerSuspended so the problem should be solved now…