Add additional critical section to the default tickless implementations.

Update version number for maintenance release.

git-svn-id: http://svn.code.sf.net/p/freertos/code/trunk@1998 1d2547de-c912-0410-9cb9-b8ca96c0e9e2

1 files changed, 11 insertions, 9 deletions

diff --git a/FreeRTOS/Source/portable/GCC/ARM_CM3/port.c b/FreeRTOS/Source/portable/GCC/ARM_CM3/port.c
index 8b0997440..741fb64b5 100644
--- a/FreeRTOS/Source/portable/GCC/ARM_CM3/port.c
+++ b/FreeRTOS/Source/portable/GCC/ARM_CM3/port.c
@@ -1,5 +1,5 @@
 /*

-    FreeRTOS V7.5.1 - Copyright (C) 2013 Real Time Engineers Ltd.

+    FreeRTOS V7.5.2 - Copyright (C) 2013 Real Time Engineers Ltd.

 

     VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

 

@@ -543,15 +543,17 @@ void xPortSysTickHandler( void )
 

 			/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG

 			again, then set portNVIC_SYSTICK_LOAD_REG back to its standard

-			value. */

+			value.  The critical section is used to ensure the tick interrupt

+			can only execute once in the case that the reload register is near

+			zero. */

 			portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;

-			portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;

-

-			vTaskStepTick( ulCompleteTickPeriods );

-

-			/* The counter must start by the time the reload value is reset. */

-			configASSERT( portNVIC_SYSTICK_CURRENT_VALUE_REG );

-			portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;

+			portENTER_CRITICAL();

+			{

+				portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;

+				vTaskStepTick( ulCompleteTickPeriods );

+				portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;

+			}

+			portEXIT_CRITICAL();

 		}

 	}