Re: [lwip-users] Problems with sending UDP packets in FreeRTOS

[Mike Fleetwood]

Hi Simon,

... in that case it must be some other bug!

Every time it crashed, I got ERR_USE.  But not only did it crash this 
thread, but killed all other LWIP functions (killing the HTTP server 
thread too - making de-bug difficult).  The RTOS seems to keep running, 
as the GPIO toggle markers still appear every 4mS (I had markers in 
other threads also, and they kept running too).

I'm beginning to wonder if there's some kind of "memory leak" 
somewhere.  I can't think where, as apart from a few "fixed" memory 
buffers - which aren't being used at the moment - the only memory usage 
is stacks allocated by the RTOS and buffers allocated by LWIP.  I have a 
status page on the HTTP server which shows the RTOS free stack for each 
thread - none anywhere near a problem level.  Is it possible to extract 
similar information from LWIP? I see in lwipopts a switch for 
statistics, but don't know how to access the results - I guess watching 
that would indicate any growing problem.

I tried one of Noam's linked examples (included below) - but that showed 
exactly the same problem, stopped sending after about 20 minutes (I 
couldn't tell if it was ERR_USE again, but no reason to think it was any 
different!).

void udp_test2(void *arg)
{
  struct netconn *conn;
  char  msg[]="testing" ;
  struct  netbuf *buf;
  char  * data;

  conn = netconn_new( NETCONN_UDP );
  netconn_bind(conn, IP_ADDR_ANY, 1234 ); //local port

  netconn_connect(conn, IP_ADDR_BROADCAST, 1235 );
  for( ;; )
  {
    buf = netbuf_new();
    data =netbuf_alloc(buf,  sizeof(msg));
    memcpy (data, msg, sizeof (msg));
    netconn_send(conn, buf);
    netbuf_delete(buf);  // De-allocate packet buffer

    osDelay(4);  //some delay!
  }
}

I altered the function name and the delay function, but otherwise it's a 
direct copy.

Many thanks,

Mike.


On 28/07/2016 10:24, Simon Goldschmidt wrote:
> Mike Fleetwood wrote:
> > Question 1: Why should send return with ERR_USE?
> It shouldn't. ERR_USE is only returned by tcp_bind() and udp_bind() (and you 
> already bound your netconn outside the loop).
> The only way it could be returned is by your netif driver's output function - 
> or due to some other bug...
>
>
> Simon
>
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