Re: [lwip-users] Problems with ASSERTION in tcp_in and tcp_out

[Justin Bayles]

I have narrowed in on the source of my problems.

When processes send tcp packets and receive ACKs at the same time, the 
pcb->snd_queuelen is being corrupted. tcp_out is busy adding PCBs to the 
send queue in tcp_enqueue() while tcp_in is pulling them out in 
tcp_receive(). It all depends on who changes the pcb->snd_queuelen first as 
to whether the process crashes in tcp_in or tcp_out.

Is this a problem that other people have experienced? Am I doing something 
wrong with my implementation.

Thanks,
Justin

> From: "Justin Bayles" <address@hidden>
> Reply-To: Mailing list for lwIP users <address@hidden>
> To: address@hidden
> Subject: Re: [lwip-users] Problems with ASSERTION in tcp_in and tcp_out
> Date: Fri, 11 Jun 2004 10:59:33 +1000
>
> Hi Leon,
>
> I am using the 0.7.2 release to do a win32 port.
>
> I am using the slip interface with Named Pipes as the physical layer. Each 
> netif connects to the Named Pipe Server. The Named Pipe Server is a 
> separate process that creates a thread to listen to each pipe. When a full 
> slip packet arrives, the thread transmits the slip packet down every pipe 
> except the pipe that the packet came from. The write is protected by a 
> semaphore so that pipes will only ever receive one slip packet at a time. 
> This has no effect on the lwip stack. It emulates a shared transmission 
> medium.
>
> I have a read process that listens for incoming connection requests, 
> connects, receives data and prints it to stdout. The read process has three 
> threads running: the tcpip thread, the slipif thread and the main thread. 
> The tcpip thread is generated by lwip. The slipif thread reads bytes from 
> the serial interface (pipe), and forwards complete slip packets to the ip 
> layer. The main thread is an infinite loop on netconn_recv, netbuf_data, 
> netbuf_delete etc.
>
> I have a write process that connects to the read process and sends packets 
> every half a second using netconn_write. The write process also has three 
> threads running: the tcpip thread, the slipif thread and the main thread.
>
> Sometime I get up to 250 successful transmissions before the ASSERTION in 
> tcp_out or tcp_in is called. I think I have a re-entrancy problem.
>
> Thanks,
> Justin
>
>
>
> > From: Leon Woestenberg <address@hidden>
> > Reply-To: Mailing list for lwIP users <address@hidden>
> > To: Mailing list for lwIP users <address@hidden>
> > Subject: Re: [lwip-users] Problems with ASSERTION in tcp_in and tcp_out
> > Date: Thu, 10 Jun 2004 18:54:00 +0200
> >
> > Hello Justin,
> >
> >
> > Justin Bayles wrote:
> >
> > > I am having trouble with the following assertions:
> > >
> > > "Assertion "tcp_enqueue: valid queue length" failed at line 139 in 
> > > .\src\core\tcp
> > > _out.c"
> > >
> > > "Assertion "tcp_receive: valid queue length" failed at line 801 in 
> > > .\src\core\tcp
> > > _in.c"
> > >
> > > Could people please suggest some possible solutions to these errors? I 
> > > have read previous posts from the archive on this topic however they have 
> > > not helped.
> > Could you mention the version of lwIP you are using? As well as some
> > details on your application.
> >
> > Regards,
> >
> > Leon.
> >
> >
> >
> > _______________________________________________
> > lwip-users mailing list
> > address@hidden
> > http://lists.nongnu.org/mailman/listinfo/lwip-users
>
> _________________________________________________________________
> What's your house worth? Click here to find out:  
> http://www.ninemsn.realestate.com.au
>
>
>
> _______________________________________________
> lwip-users mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/lwip-users

_________________________________________________________________
Get a Credit Card - 60 sec online response:   
http://ad.au.doubleclick.net/clk;8097459;9106288;b?http://www.anz.com/aus/promo/qantas5000ninemsn 
  [AU only]