Usage of configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES

Kernel
1

gezab wrote on Tuesday, June 14, 2016:

Hi all,

I am developing a new project and therefore I set the above define to 1, in order to catch list corruptions. I also have configASSERT() defined and it broke execution when my first static semaphore was about to be created, since Queue_t and StaticQueue_t are not of the same size. In order to get rid of the error, I needed to make the following changes in FreeRTOS.h:

/*
 * In line with software engineering best practice, FreeRTOS implements a strict
 * data hiding policy, so the real structures used by FreeRTOS to maintain the
 * state of tasks, queues, semaphores, etc. are not accessible to the application
 * code.  However, if the application writer wants to statically allocate such
 * an object then the size of the object needs to be know.  Dummy structures
 * that are guaranteed to have the same size and alignment requirements of the
 * real objects are used for this purpose.  The dummy list and list item
 * structures below are used for inclusion in such a dummy structure.
 */
struct xSTATIC_LIST_ITEM
{
#if( configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES == 1 )
    TickType_t uxDummy0;
#endif /* configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES */
	TickType_t xDummy1;
	void *pvDummy2[ 4 ];
#if( configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES == 1 )
    TickType_t uxDummy3;
#endif /* configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES */
};
typedef struct xSTATIC_LIST_ITEM StaticListItem_t;

/* See the comments above the struct xSTATIC_LIST_ITEM definition. */
struct xSTATIC_MINI_LIST_ITEM
{
#if( configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES == 1 )
    TickType_t uxDummy0;
#endif /* configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES */
	TickType_t xDummy1;
	void *pvDummy2[ 2 ];
};
typedef struct xSTATIC_MINI_LIST_ITEM StaticMiniListItem_t;

/* See the comments above the struct xSTATIC_LIST_ITEM definition. */
typedef struct xSTATIC_LIST
{
#if( configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES == 1 )
    TickType_t uxDummy0;
#endif /* configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES */
	UBaseType_t uxDummy1;
	void *pvDummy2;
	StaticMiniListItem_t xDummy3;
#if( configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES == 1 )
    TickType_t uxDummy4;
#endif /* configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES */
} StaticList_t;

This way, even if the define in the subject is set to 1, the sizes of Queue_t and StaticQueue_t are equal and the assert is passing.

Can this be an intentional thing? Are we allowed to use the list integrity checker in our applications?

Regards,
Geza

2

rtel wrote on Tuesday, June 14, 2016:

Sure you can use the list integrity checker in your application if you like, but note it was not intended for use by applications, and as such is not documented - and the issue you have noticed (which we will look at - thanks for reporting) reflects that. The integrity checking code is included in our code coverage tests.

3

gezab wrote on Tuesday, June 14, 2016:

Thanks for your reply. I was debugging a weird phenomenon that was
corrupting my RAM, this is why I turned it on (unfortunately I do not have
data tracing equipment and the problem showed up only occasionally). It
really helped me to get closer to the problem which I already managed to
sort out, that is why I think it would make sense to have this as an
official option for applications, too.