Re: [lwip-devel] TCP Client system fault

[Vinicius Bernardi]

Hi All,

I finally found the reason about the TCP is receiving a corrupt package , I 
will try to explain the process : 

1 - I had writen some data using netconn_write 
Then I had received a semaphore post saying that the TCPIP thread already 
process that message

Then PPP thread receive a package (IP buffer) and process it, but during the 
process of that package the code decide to call do_write method again ( it's 
related to SEND EVENT about the message confirmed - previous message maybe ) 

With this new POST again at semaphore, my next write to netconn_write will be 
out of sync, because I will not wait again, as my semaphore it's already 1 , 
and it will be released imediatly.

In my solution for now it's to remove the do_writemore inside of API to send 
signal, as there is no sense to be there.

I would like some comments if it's possible.

Another important question :

I'm trying to write huge packages, 1600 bytes for example, how the 
netconn_write should handle it? Right now, there is a output of 1400 bytes and 
I receive ACK that everything it's ok, and it's not ok, there is a part of 
package missing.

My best regards,
Vinicius


Em 14/04/2012, às 16:31, Vinicius Bernardi escreveu:

> Hi Everyone,
> 
> I`m facing a issue that is very complex to understand how it's happening.
> The issue happens like this : 
> 
> I have a PPP connection + TCP Client, I keep just 1 client connection open.
> This connection can be used for many hours without any problem, sending and 
> receiving packages.
> But if I decide to send a huge buffer (1400 bytes) with very short interval, 
> as I receive the TCP ACK, I send a new one, the code is generating a system 
> fault.
> I'm using a RTOS uC/OS-II port, and as I said it's working very well, even 
> with Huge buffers in case that the interval it's bigger.
> I already increase STACK size, buffer's sizes, but as far as I don't know 
> when the problem will happens, and sometimes it happnes in 50 seconds, 
> sometimes with 300 seconds after I had start it, it's vey complex to 
> understand why the system fault it`s cause by.
> The it`s always in the same state, and the data is 0x00000000.
> I'm using a Cortex M4.
> Does anybody have some clue, or additional information how can I debbug it, 
> and get more information?
> I already have all the trace information enabled, and I didn't find a route 
> cause, or a different sittuation inside the log.
> 
> My best regards,
> Vinicius