Re: [lwip-users] LWIP capabilities

[Robert Morse]

On Apr 18, 2007, at 4:44 PM, Jonathan Larmour wrote:

> Robert Morse wrote:
>
> >     My driver, in the receive interrupt, just messages a HIGH 
> > priority task, to actually
> > handle passing the data into the lwip stack.
>
> How specifically does it do that? Does it call etharp_ip_input() 
> directly for example?

I have an task that waits for a message from the ethernet interrupt 
handler.
It then does:

loop {
        sys_arch_mbox_fetch( handler_mbox, &dummy, 0 );
        while ( (pbuf = low_level_input()) != NULL )
        {
                switch( ethhdr->type )
                        case ETHTYPE_IP:
                                ....
                        case THETYPE_ARP:
                                etharp_arp_input(netif, addr, pbuf)
        }
}
I had this all done in the interrupt routine, but trying to protect the 
memory allocation
for both interrupt and task, just did not seem like it was that 
protective of each other.
So I created a task that did the creating of the pbufs.


> Although I can't see any immediate problem in what is in your 
> description, this sounds a lot like an inter-thread locking problem of 
> some sort.

Ya, that is what I think it is.

> I assume you are using the sequential (netconn) API. The most obvious 
> thing to bear in mind is that the thread-safety is limited - you 
> should only use one connection in one thread at one time. You can't 
> use the same connection in two different threads at one time.

I am using the 'bsd' interface, socket, accept, send, recv. Which I 
believe sit on top of the netconn layer.

The only place where two threads interact is I have a thread doing a 
listen, which then passes the
return socket to another thread that does all the communications. So I 
guess you would say that one
thread is doing an open, while another thread is doing everything else 
up to the close.


Ok,
	This is what I wanted to hear. I will keep looking at where a possible 
dead lock is happening.

Robert


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