From 3bcdee89c604dfe3f8cfb5977ff5276fe6ffde10 Mon Sep 17 00:00:00 2001 From: Jeff Tenney Date: Tue, 9 Jun 2020 16:45:27 -0700 Subject: [PATCH] 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(). --- include/task.h | 2 +- tasks.c | 15 ++++++++++++++- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/include/task.h b/include/task.h index 3eaf6eecb..15afca429 100644 --- a/include/task.h +++ b/include/task.h @@ -2822,7 +2822,7 @@ void vTaskSetTaskNumber( TaskHandle_t xTask, const UBaseType_t uxHandle ) PRIVIL * 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 67b7de203..1046791a4 100644 --- a/tasks.c +++ b/tasks.c @@ -2599,12 +2599,25 @@ implementations require configUSE_TICKLESS_IDLE to be set to a value other than 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 != 0 ); + + taskENTER_CRITICAL(); + xPendedTicks++; + taskEXIT_CRITICAL(); + xTicksToJump--; + } xTickCount += xTicksToJump; traceINCREASE_TICK_COUNT( xTicksToJump ); }