RTOS/CC2640R2F: RTOS Queue issue

GOHM ELECTRONICS

Expert 2065 points

Part Number: CC2640R2F
Other Parts Discussed in Thread: SYSBIOS

Tool/software: TI-RTOS

Hi all,

I am trying to fill queue with messages. After filling some messages, i will iterate queue and remove some messages on any spesific place(middle, tail or head). When i try removing messages with this code in below, program crashes after some time.

        if (!Queue_empty(outgoingMsgQueue))
        {
            Queue_Elem *pRec;
            pRec = Queue_head(outgoingMsgQueue);
            for (pRec = Queue_head(outgoingMsgQueue); pRec != (Queue_Elem *) outgoingMsgQueue; pRec = Queue_next(pRec))
            {
                queueRec_t * questr = (queueRec_t*) pRec;
                sbpUARTEvt_t *pMsg = (sbpUARTEvt_t *) questr->pData;
                if (pMsg)
                {

                        Queue_remove(pRec);
                        ICall_free(pRec);
                        ICall_freeMsg(pMsg->pData);
                        ICall_free(pMsg);
                }
             }
        }

It goes HWI in Queue_remove(pRec);

HW exception :

Exception call stack

0 ti_sysbios_knl_Queue_remove__E at Queue.c:219 :

PC=0x1001BF66

In Queue.c 219:

qelem->next->prev = qelem->prev;
This line occurs hardware fault. According to Runtime Object view.

But when i try with this, it works properly

        if (!Queue_empty(outgoingMsgQueue)) //no ack msg but there are msgs sent
        {
            Queue_Elem *pRec;
            pRec = Queue_head(outgoingMsgQueue);
                queueRec_t * questr = (queueRec_t*) pRec;
                sbpUARTEvt_t *pMsg = (sbpUARTEvt_t *) questr->pData;
                if (pMsg)
                {
                        Queue_remove(pRec);
                        ICall_free(pRec);
                        ICall_freeMsg(pMsg->pData);
                        ICall_free(pMsg);
                }
        }

So, when i iterate with for loop, program stucks after some time . What can be the problem ?

Best regards.

over 6 years ago

0 Evan Wakefield over 6 years ago

TI__Mastermind 38920 points

Hi,

Let me dig into this a bit and examine it and I'll respond by tomorrow.

0 Evan Wakefield over 6 years ago in reply to Evan Wakefield

TI__Mastermind 38920 points

Hi,

My concern is that your code is not thread safe. What threads are potentially adding and removing elements? If this is a task, and it's traversing a linked list and a higher priority thread (hwi, swi or task) changes the linked list, trouble could happen.

Also, when you are adding elements to the queue, where is the memory coming from? You must allocate a unique block for each element. Maybe ICall is doing this hence you calling ICall_free etc, but it would be good to verify this.

0 GOHM ELECTRONICS over 6 years ago in reply to Evan Wakefield

Expert 2065 points

Hi Evan,

thank you for your answer. Firstly, one task will put message to this queue and another one task will wait for events with timeout. If timeout occurs or event occurs it will remove messages using some spesific pattern if any message is available in queue. So in here, one supplier/ one consumer methodology is available.

My enqueue function is that;

void ACK_H_enqueueOutgoingMsg(uint8_t event, uint8_t *data, uint8_t len)
{
    sbpUARTEvt_t *pMsg;
    queueRec_t *pRec;

    //Enqueue message only in a connected state
    if (isBLEConnected())
    {
        // Create dynamic pointer to message.
        if (pMsg = ICall_malloc(sizeof(sbpUARTEvt_t)))
        {
            pMsg->event = event;
            pMsg->pData = (uint8 *) ICall_allocMsg(len);
            if (pMsg->pData)
            {
                memcpy(pMsg->pData, data, len);
            }
            pMsg->length = len;
            // Enqueue the message.
            if ((pRec = ICall_malloc(sizeof(queueRec_t))))
            {
                pRec->pData = (uint8*) pMsg;
                // This is an atomic operation
                Queue_put(outgoingMsgQueue, &pRec->_elem);
                Event_post(ackEvtHandle, ONGOING_MSG_EVT);
            }
            else
            {
                ICall_free(pMsg);
            }
        }
    }
}

I allocate memory for each message. I disassamle the problem and these are what i get.

Decoded exception
Decoded   Hard Fault: FORCED: BUSFAULT: IMPRECISERR
Exception context
$addr   N/A
$type   ti.sysbios.family.arm.m3.Hwi.ExcContext
threadType   Task
threadHandle   0x20001a20
threadStack   0x20001a70
threadStackSize   512
r0   0x10000
r1   0x80000024
r2   0x80000024
r3   0x20003500
r4   0x200019f8
r5   0x20003518
r6   0xffffffff
r7   0x6010207
r8   0xffffffff
r9   0xffffffff
r10   0xffffffff
r11   0xffffffff
r12   0x20003714
sp   0x20001c18
lr   0xa7cd
pc   0x1001bf66
psr   0x81000000
ICSR   0x414803
MMFSR   0x0
BFSR   0x4
UFSR   0x0
HFSR   0x40000000
DFSR   0x0
MMAR   0xe000edf8
BFAR   0xe000edf8
AFSR   0x0
Exception call stack
0 ti_sysbios_knl_Queue_remove__E at Queue.c:219 :   PC=0x1001BF66
1 ACK_H_application_taskFxn at ack_handler.c:175 :   PC=0x0000A7CC

This is raw registers when cortex goes to Hard fault.

Program counter in memory:

Link register in memory:

Everything looks fine but program crashes after some time when i traverse linked list.

Regards.

0 Evan Wakefield over 6 years ago in reply to GOHM ELECTRONICS

TI__Mastermind 38920 points

Hey there,

Thanks for the extra details! I think i know the issue. After you call ICall_free(pRec); pRec should not be used as it is used within the for loop as well and you would be trashing pRec for the rest of your for loop iterations.

You don't need the check for empty either assuming you're popping everything off, not just when it has a pMsg. If that's not true, the logic would change a bit but make sure to get pRec = Queue_next(pRec) before you free pRec.

This code below should be roughly what you're looking for.

Queue_Elem *pRec; 
while (pRec = Queue_head(outgoingMsgQueue) != (Queue_Elem *) outgoingMsgQueue) {; 
{ 
    queueRec_t * questr = (queueRec_t*) pRec; 
    sbpUARTEvt_t *pMsg = (sbpUARTEvt_t *) questr->pData; 
    Queue_remove(pRec); // assuming you always want to remove it, not just it has a message
    ICall_free(pRec);  
    if (pMsg) 
    { 
            ICall_freeMsg(pMsg->pData); 
            ICall_free(pMsg); 
    } 
}

0 GOHM ELECTRONICS over 6 years ago in reply to Evan Wakefield

Expert 2065 points

Hi Evan,

I want to check time of messages in queue and if time of message is expired i will remove this message. So, i will not remove every message in queue.
But the way you suggest is very logical. I will apply this to my methodology and i will remove 1 message every time. So queue will not be crashed.
Thank you for your support.

Best regards.

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RTOS/CC2640R2F: RTOS Queue issue