SIMPLELINK-WIFI-CC3120-SDK-PLUGIN: SL_DEVICE_EVENT_FATAL_DRIVER_ABORT occurs in sl_SendTo under weak radio quality

I am a FAE of a Distributor in Japan.

My customer has a problem.

SL_DEVICE_EVENT_FATAL_DRIVER_ABORT occurs in sl_SendTo when multiple UDP communications are performed in an environment with weak radio quality.
They checked the details and found that TxPoolCnt was 4 at the beginning of the _SlDrvDataWriteOp function (# 1), but TxPoolCnt was 2 at VERIFY_PROTOCOL (# 2).
It seems that the spawn task is executed between # 1 and # 2, and TxPoolCnt is changed to 2 by the _SlDrvMsgRead function.

- Is there anything the TxPoolCnt suddenly update to the minimum value?
- Can you give me advice on how to avoid this issue?

/* ******************************************************************************/
/*   _SlDrvDataWriteOp                                                          */
/* ******************************************************************************/
_SlReturnVal_t _SlDrvDataWriteOp(_SlSd_t Sd,
                                 _SlCmdCtrl_t  *pCmdCtrl,
                                 void                *pTxRxDescBuff,
                                 _SlCmdExt_t         *pCmdExt)
{
    _SlReturnVal_t RetVal = SL_ERROR_BSD_EAGAIN;  /*  initiated as SL_EAGAIN for the non blocking mode */
    _u32 allocTxPoolPkts;

    while(1)
    {
        /*  Do Flow Control check/update for DataWrite operation */
        SL_DRV_OBJ_LOCK_FOREVER(&g_pCB->FlowContCB.TxLockObj);

                                :

        if(g_pCB->FlowContCB.TxPoolCnt <= FLOW_CONT_MIN + allocTxPoolPkts)                                      ----> (#1)
        {
            /*  we have indication that this socket is set as blocking and we try to  */
            /*  unblock it - return an error */
            if(g_pCB->SocketNonBlocking & (1 << (Sd & SL_BSD_SOCKET_ID_MASK)))
            {
#if (defined (SL_PLATFORM_MULTI_THREADED)) && \
                (!defined (SL_PLATFORM_EXTERNAL_SPAWN))
                if(_SlDrvIsSpawnOwnGlobalLock())
                {
                    _SlInternalSpawnWaitForEvent();
                }
#endif
                SL_DRV_OBJ_UNLOCK(&g_pCB->FlowContCB.TxLockObj);
                return(RetVal);
            }
            /*  If TxPoolCnt was increased by other thread at this moment, */
            /*  TxSyncObj won't wait here */
#if (defined (SL_PLATFORM_MULTI_THREADED)) && \
            (!defined (SL_PLATFORM_EXTERNAL_SPAWN))
            if(_SlDrvIsSpawnOwnGlobalLock())
            {
                while(TRUE)
                {
                    /* If we are in spawn context, this is an API which was called from event handler,
                       read any async event and check if we got signaled */
                    _SlInternalSpawnWaitForEvent();
                    /* is it mine? */
                    if(0 ==
                       sl_SyncObjWait(&g_pCB->FlowContCB.TxSyncObj,
                                      SL_OS_NO_WAIT))
                    {
                        break;
                    }
                }
            }
            else
#endif
            {
                SL_DRV_SYNC_OBJ_WAIT_FOREVER(&g_pCB->FlowContCB.TxSyncObj);
            }
        }
        if(g_pCB->FlowContCB.TxPoolCnt > FLOW_CONT_MIN + allocTxPoolPkts)
        {
            break;
        }
        else
        {
            SL_DRV_OBJ_UNLOCK(&g_pCB->FlowContCB.TxLockObj);
        }
    }

    SL_DRV_LOCK_GLOBAL_LOCK_FOREVER(GLOBAL_LOCK_FLAGS_UPDATE_API_IN_PROGRESS);

    /* In case the global was succesffully taken but error in progress
       it means it has been released as part of an error handling and we should abort immediately */
    if(SL_IS_RESTART_REQUIRED)
    {
        SL_DRV_LOCK_GLOBAL_UNLOCK(TRUE);
        return(SL_API_ABORTED);
    }

    /* Here we consider the case in which some cmd has been sent to the NWP,
       And its allocated packet has not been freed yet. */
    VERIFY_PROTOCOL(g_pCB->FlowContCB.TxPoolCnt >
                    (FLOW_CONT_MIN + allocTxPoolPkts - 1));                                                         ----> (#2)
    g_pCB->FlowContCB.TxPoolCnt -= (_u8)allocTxPoolPkts;

    SL_DRV_OBJ_UNLOCK(&g_pCB->FlowContCB.TxLockObj);

    SL_TRACE1(DBG_MSG, MSG_312, "\n\r_SlDrvCmdOp: call _SlDrvMsgWrite: %x\n\r",
              pCmdCtrl->Opcode);

    /* send the message */
    RetVal = _SlDrvMsgWrite(pCmdCtrl, pCmdExt, pTxRxDescBuff);
    SL_DRV_LOCK_GLOBAL_UNLOCK(TRUE);

    return(RetVal);
}

The environments they use are:

• SDK Version : 2.40.00.22 (simplelink_sdk_wifi_plugin_2_40_00_22.exe)
• Service Pack : 3.11.1.0_2.0.0.0_2.2.0.6 (CC3x20ServicePack-3.11.1.0_2.0.0.0_2.2.0.6-windows-installer(2.40.00.22).exe)
• Host OS : RTX OS (MCU: Renesas RZ/A1H)

Thank you for advice.

Regards,

Yojiro