From 990643ebe8c990dd3672a52079d274e7685df980 Mon Sep 17 00:00:00 2001 From: Jeff Tenney Date: Mon, 10 Jan 2022 12:44:12 -0700 Subject: [PATCH] Fix support for stepping tick by xExpectedIdleTime (#73) * Fix support for stepping maximum number of ticks This commit fixes support for tickless implementations that call vTaskStepTick() with the maximum number of allowed ticks to step. vTaskStepTick() --------------- Function vTaskStepTick() provides a way for the tickless idle implementation to account for ticks that elapse during tickless idle. The maximum number of stepped ticks allowed is the number passed to portSUPPRESS_TICKS_AND_SLEEP(). It is the number of ticks between xTickCount and xNextTaskUnblockTime. vTaskStepTick() is specifically intended for use with tickless idle, so it always executes with the scheduler disabled. For reference, compare it with the more general function xTaskCatchUpTicks(). Without this Change ------------------- Prior to this commit, if a task is supposed to wake at xTickCount == 0xFFFFFFFF, then when tickless idle ends, function vTaskStepTick() sets the tick to 0xFFFFFFFF but the task remains on the delayed list because xTaskIncrementTick() does not execute. One tick later, xTaskIncrementTick() executes because it's time to increment xTickCount to 0x00000000. An assertion failure occurs in taskSWITCH_DELAYED_LISTS() because the delayed task list is not empty. Other examples of valling vTaskStepTick() with the maximum allowed number of ticks merely result in a task waking one tick late. Default Tickless Implementations -------------------------------- Note that the default tickless implementations never pass the maximum allowed value to vTaskStepTick(). The default implementations use the tick interrupt to finish the sleep and allow that one tick to be counted normally via the tick ISR and xTaskIncrementTick(). * Protect xPendedTicks with critical section Function xTaskIncrementTick() increments xPendedTicks when the scheduler is disabled. That function typically executes inside the tick ISR. So code in xTaskCatchUpTicks() must mask interrupts when modifying xPendedTicks. * uncrustify tasks.c * Update tasks.c Style changes only - added comment and indentation to the two modified files. * uncrustify * Add test coverage for new conditional * Add typecast Co-authored-by: Cobus van Eeden <35851496+cobusve@users.noreply.github.com> Co-authored-by: Joseph Julicher Co-authored-by: RichardBarry <3073890+RichardBarry@users.noreply.github.com> --- include/task.h | 2 +- tasks.c | 32 ++++++++++++++++++++++++++++++-- 2 files changed, 31 insertions(+), 3 deletions(-) diff --git a/include/task.h b/include/task.h index 007900f2a..f35a8d703 100644 --- a/include/task.h +++ b/include/task.h @@ -3079,7 +3079,7 @@ void vTaskSetTaskNumber( TaskHandle_t xTask, * to date with the actual execution time by being skipped forward by a time * equal to the idle period. */ -void vTaskStepTick( const TickType_t xTicksToJump ) PRIVILEGED_FUNCTION; +void vTaskStepTick( TickType_t xTicksToJump ) PRIVILEGED_FUNCTION; /* * Only available when configUSE_TICKLESS_IDLE is set to 1. diff --git a/tasks.c b/tasks.c index 88e699ca6..917b1986e 100644 --- a/tasks.c +++ b/tasks.c @@ -2592,12 +2592,34 @@ char * pcTaskGetName( TaskHandle_t xTaskToQuery ) /*lint !e971 Unqualified char * 1. */ #if ( configUSE_TICKLESS_IDLE != 0 ) - void vTaskStepTick( const TickType_t xTicksToJump ) + void vTaskStepTick( TickType_t xTicksToJump ) { /* Correct the tick count value after a period during which the tick * was suppressed. Note this does *not* call the tick hook function for * each stepped tick. */ configASSERT( ( xTickCount + xTicksToJump ) <= xNextTaskUnblockTime ); + + if( ( xTickCount + xTicksToJump ) == xNextTaskUnblockTime ) + { + /* Arrange for xTickCount to reach xNextTaskUnblockTime in + * xTaskIncrementTick() when the scheduler resumes. This ensures + * that any delayed tasks are resumed at the correct time. */ + configASSERT( uxSchedulerSuspended ); + configASSERT( xTicksToJump != ( TickType_t ) 0 ); + + /* Prevent the tick interrupt modifying xPendedTicks simultaneously. */ + taskENTER_CRITICAL(); + { + xPendedTicks++; + } + taskEXIT_CRITICAL(); + xTicksToJump--; + } + else + { + mtCOVERAGE_TEST_MARKER(); + } + xTickCount += xTicksToJump; traceINCREASE_TICK_COUNT( xTicksToJump ); } @@ -2616,7 +2638,13 @@ BaseType_t xTaskCatchUpTicks( TickType_t xTicksToCatchUp ) /* Use xPendedTicks to mimic xTicksToCatchUp number of ticks occurring when * the scheduler is suspended so the ticks are executed in xTaskResumeAll(). */ vTaskSuspendAll(); - xPendedTicks += xTicksToCatchUp; + + /* Prevent the tick interrupt modifying xPendedTicks simultaneously. */ + taskENTER_CRITICAL(); + { + xPendedTicks += xTicksToCatchUp; + } + taskEXIT_CRITICAL(); xYieldOccurred = xTaskResumeAll(); return xYieldOccurred;