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

[Leon Woestenberg]

Hello Justin,

interesting. Let me ask a few questions before making false assumptions.

you describe your application as having a read and write process. Do
they
share one instance of lwIP or do they each have an instance of lwIP?

On Tue, 15 Jun 2004 15:43:27 +1000, "Justin Bayles"
<address@hidden> said:
> I have narrowed in on the source of my problems.
> 
> When processes send tcp packets and receive ACKs at the same time, the 
>
What exactly do you mean by "at the same time"? Do you mean the SLIP
receive
thread can be pre-empted by the TCP thread and vice versa.?

> 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.
> 
Are you directly calling the tcp_*() functions?

> Is this a problem that other people have experienced? Am I doing
> something 
> wrong with my implementation.
> 
Well, at least we should find out what is wrong. In the best case, we
need to document lwIP better.

Regards,

Leon.

> 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.
> >>
> >>
> >>
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> >
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