MQX_CHECK_VALIDITY

alessandrobiasc — Thu, 07 Jul 2016 09:01:23 GMT

Hi all,

I have a general question about the code executed if MQX_CHECK_VALIDITY is set.

This is an example of _lwsem_post from MQX 4.2.2 :

_mqx_uint _lwsem_post
(
    LWSEM_STRUCT_PTR sem_ptr
)
{ /* Body */
/* ...... */
#if MQX_CHECK_VALIDITY
    if (sem_ptr->VALID != LWSEM_VALID)
    {
        _KLOGX2(KLOG_lwsem_post, MQX_INVALID_LWSEM);
        return (MQX_INVALID_LWSEM);
    } /* Endif */
#endif /* MQX_CHECK_VALIDITY */
/* ...... */

My question is:

Why this code is executed without any kind of mutual exclusion (mutex, interrupt disable, ...) ? The current task can be preempted during the check and another task can "validate/invalidate" the lwsem. I'm missing something in the implementation (sorry for this) ?

Regards,

Alessandro.

Re: MQX_CHECK_VALIDITY

danielchen — Thu, 07 Jul 2016 22:22:20 GMT

Hi Alessandro,

Actually, this code is executed with interrupt disable, it is wrapped in the macro. Please check the macro _KLOGX2 defines.

#define _KLOGX2(fn,p1) _KLOG(_klog_log(KLOG_FUNCTION_EXIT, \

(_mqx_max_type)(fn), (_mqx_max_type)(p1), (_mqx_max_type)0, (_mqx_max_type)0, (_mqx_max_type)0);)

void _klog_log

(

_mqx_uint type,

_mqx_max_type p1,

_mqx_max_type p2,

_mqx_max_type p3,

_mqx_max_type p4,

_mqx_max_type p5

)

{ /* Body */

...

	_INT_DISABLE();
	_lwlog_write(LOG_KERNEL_LOG_NUMBER, (_mqx_max_type)type, p1, p2, p3, p4, p5,
	calling_pc);
	_INT_ENABLE();

...

}

Have a great day,
Daniel

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