[lwip-users] help. pcb->next = pcb!

[Eric Shufro]

For some reason, the pcb I use to transmit data gets its next pointer set to
itself! As a result, loops that rely on pcb=somepcb; pcb!=NULL;
pcb=pcb->next become infinite loops!

I tried to trace this down without much luck. What could the problem be?

Thanks.

Here is some trace output as well...

tcp_connect to port 3000
tcp_enqueue(pcb=24F0, arg=0, len=0, flags=2, copy=0)
tcp_enqueue: queueing 6553:6554 (0x2)
tcp_output_segment: 6553:6553
tcp_write(pcb=24F0, arg=3030, len=25, copy=1)
tcp_enqueue(pcb=24F0, arg=3030, len=25, flags=0, copy=1)
tcp_enqueue: queueing 6554:6579 (0x0)
tcp_output_segment: 6554:6579
tcp_slowtmr: processing active pcb
tcp_slowtmr: polling application
tcp_output: nothing to send (0)
tcp_receive: window update 65510
tcp_close: closing in state State: ESTABLISHED

tcp_enqueue(pcb=24F0, arg=0, len=0, flags=1, copy=1)
tcp_enqueue: queueing 6579:6580 (0x1)
tcp_output_segment: 6579:6579
tcp_output: nothing to send (0)
tcp_receive: window update 65510
tcp_close: closing in state State: FIN_WAIT_2

tcp_output: nothing to send (0)
TCP connection closed 3000 -> 4097.
tcp_pcb_purge
tcp_close: closing in state State: TIMtcp_slowtmr: no active pcbs


At this point it becomes stuck in tcp_slowtmr, under the infinite loop
conditions mentioned above.


The way i setup to send the data is like this starting from the ISR which
signals the send task to do its work... sorry about the formatting. <shrug>

Thanks for the help,

-eric

****************************************************************************
*****************************
*                        TASK: Send received RS232 data via TCP to the host 
****************************************************************************
*****************************
*/

void tcpSendData(struct netif *netif) 
{      
   volatile err_t err;
   INT8U i;
   
   rs232ReadySem = sys_sem_new(0);
   SCI0CR2 = 0x2C;                                         /* enable SCI0
receive interrupts                  */
   
   if(*eeIdentFlag > 0)
/* if identification is enabled, */
   {
      for(i=0; i<5;i++)
/* copy the mac address into the */
         rs232Data[i] = eeMACAddr[i];
/* data buffer to be transmitted */      
      rs232DataIndex = 6;                                  /* initialize the
data index to point to the next available location */
   }
   else
      rs232DataIndex = 0;                                  /* initialize the
data index to point to the next available location */

      
   while(TRUE) 
   {
      OSSemPend(rs232ReadySem, 0, &err);
      //sys_sem_wait(rs232ReadySem);
      
      /* if awakened figure out transmit options and do a   */
      /* tcpwrite rs232 data to the correct destination     */
      
      IP4_ADDR(&tempIP, *eeDestIP1, *(eeDestIP1+1), *(eeDestIP1+2),
*(eeDestIP1+3));      
      err = tcp_connect(packTxPCB, &tempIP, *((INT16U *)eeDestPort),
tcpOutConnEstab);                  
   }            
}

/*
****************************************************************************
*****************************
*                       Outgoing TCP connection estabolished
****************************************************************************
*****************************
*/

err_t tcpOutConnEstab(void *arg, struct tcp_pcb *packTxPCB, err_t err)
{
   err_t result;   
   result = tcp_write(packTxPCB, &rs232Data[0], 25, 1); 
   tcp_sent(packTxPCB, packDataSentOK);                 /* register call
back for host recieved the data ok */            
   
   if(*eeIdentFlag > 0)
      rs232DataIndex = 6;
/* if ident is on, preserve the first 5 bytes of the */
   else
/* data array, the MAC Address is stored there       */
      rs232DataIndex = 0;                               /* reset the pointer
into the array                  */
   SCI0CR2 = 0x2C;                                      /* re-enable SCI0
Receiver Interrupts                */
   return result;     
}
   
/*
****************************************************************************
*****************************
*                 data was transmitted and received by the remote host 
****************************************************************************
*****************************
*/

err_t packDataSentOK (void *arg, struct tcp_pcb *packTxPCB, u16_t len) 
{
   tcp_close(packTxPCB);   
   return ERR_OK;
}


/*
****************************************************************************
*****************************
*                                           SCI0 - Serial Port Receive
Interrupt
****************************************************************************
*****************************
*/

#pragma CODE_SEG __NEAR_SEG INTERRUPT_ROUTINES
#pragma TRAP_PROC
interrupt void SCI0RxTxISR(void) 
{

   if( ((SCI0SR1 & 0x20) == 0x20) && rs232DataIndex < rs232InBufSize)    /*
if the interrupt indicates a received byte */
   {                                                                     /*
and the data array is not full             */
      rs232Data[rs232DataIndex++] = SCI0DRL;                             /*
add the new data byte to the array                  */   
 
/* and increment the point to the next location        */
      if(rs232DataIndex == 25)                                           /*
did we receive the last byte from the host?         */

      {
         SCI0CR2 = 0x0C;                                                 /*
disable rs232 receive interrupts (SR re-enables it  */
         
         OSIntNesting++;                                                 /*
notify the OS about the interrupt       */
   
         if (OSIntNesting == 1) 
         {
            __asm{
               ldy OSTCBCur                                              /*
OSTCBCur->OSTCBStkPtr = Stack Pointer   */
               sts    0,y                             
            }
         }   
               
         OSSemPost(rs232ReadySem);
         //sys_sem_signal(rs232ReadySem);
/* signal the TCP tx task that there is work to do.    */
      
         OSIntExit();
      }   
   }
}
#pragma CODE_SEG DEFAULT