[lwip-users] threading....

[Eric Shufro]

I am having all sorts of problems(system crashing) here and I think they may
be due to threading still. Please tell me what you think based on this
scenario. I appreciate the help.

-eric

(ucos+lwip+cs8900)

//----------------------------------------------------------------------

Main() initializes the OS and creates 2 tasks. 1 called AppStartTask, and
another which is the CS8900 interrupt handler. :

    OSInit();

    sys_init();
    mem_init();
    memp_init();
    pbuf_init();
     
    printf("System initialized.\n\x0a");

    sys_thread_new(AppStartTask,  AppStartTask,  TASK_START_PRIO);
    sys_thread_new(ServiceCS8900, ServiceCS8900 ,TASK_START_PRIO); 

    EnableInterrupts;
    OSStart();                              

//----------------------------------------------------------------------

AppStartTask initializes LWIP and the system ticker and blinks and LED
indefinitely like so:

As you can see, AppStartTask initializes / creates yet another task, the
TCPIP_Thread().

struct ip_addr ipaddr, netmask, gw;
sys_sem_t sem;
struct netif *pstNetif;

  (void)p_arg; 
  
  OSTickISR_Init();               

  sem = sys_sem_new(0);  
  tcpip_init(tcpip_init_done, &sem);
  sys_sem_wait(sem);
  sys_sem_free(sem);
  printf("TCP/IP initialized.\n\x0a");
  
  netif_init();

  IP4_ADDR(&gw, 192,168,0,1);
  IP4_ADDR(&ipaddr, 192,168,0,103);
  IP4_ADDR(&netmask, 255,255,255,0);

  pstNetif = netif_add(&pstNetif, &ipaddr, &netmask, &gw, NULL,        
  cs8900if_init, ip_input);
  LWIP_ASSERT("TaskStart: netif_add error, pstNetif != 0\n", pstNetif != 0);
  netif_set_default(pstNetif);

  printf("netif initialized, toggling led now\n\x0a");
  while (TRUE) 
  {
      LED_Toggle(4);
      OSTimeDly(OS_TICKS_PER_SEC);
  }

//----------------------------------------------------------------------

Additionally, when an interrupt occurs, the ISR disables the CS8900
interrupt pin, and posts a semaphore to the CS8900 interrupt hander which
runs, re-enables interrupts, and then pends again when complete.

  INT16U isq_data;         
  extern struct netif *pstNetif;
  
  cs8900sem = sys_sem_new(0);             
   
   printf("CS8900 Interrupt Handler starting...\n");
   
   while(1)
   {
      printf("interrupt handler now asleep\n\x0a");
      sys_sem_wait(cs8900sem);
      printf("interrupt handler now awake\n\x0a");
                   
      do
      {
         isq_data = IORead(CS8900_ISQ) >> 8;
                           
         switch(isq_data & 0x3f)
           {
              case 0x00:        //isq is empty. exit.
                 break;
              case 0x04:        //receieve event
cs8900if_input(&pstNetif);
                 break;
              case 0x08:                //transmit event
               break;
            case 0x0C:          //buffer event  
               break;
            case 0x10:          //receiver miss event              
                   break;
              case 0x12:                //transmit collision event
               break;
            default:

               break;
           } 
      }while(isq_data != 0);        
      
      INTCR = 0x40;                       //re-enable interrupts        

So anyway, with this scheme, it seems that there could be problems when the
ISR handler is reading in a packet, and if the stack wanted to write one at
the same time. So, the threads need to be synchronized with another
semaphore to block even the arp routine from sending an arp response when
the interrupt handler is running..

I believe that could be part of the reason why the system is crashing?? Im
not completely sure yet.

Additionally, where in this model would I call the lwip timers?

Should that be done from one of the existing threads, or put all the timers
into 1 new thread and use the OSTimeDelay() - Which wouldn't exactly work
since a delay of 1 second would cause the finer timers to not get called..

Thanks again for the help,

--eric