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

From: K.J. Mansley
Subject: Re: [lwip-users] Problems with ASSERTION in tcp_in and tcp_out
Date: 17 Jun 2004 18:11:15 +0100

On Thu, 2004-06-17 at 17:50, Leon Woestenberg wrote:
> Hello Justin,
> Justin Bayles wrote:
> >> I am not into the netconn_ layer, but shouldn't the sysarch semaphores 
> >> already synchronize access to the TCP layer? I.e. are you really seeing
> >> concurrent access to both tcp_in and tcp_enqueue?
> > 
> > There is no synchronisation in either tcp_in or tcp_out. I am definitely 
> > seeing concurrent access to tcp_in and tcp_out.
> >
> Yes, the lwIP core does no synchronization whatsoever (by design). The
> higher layer should handle this.
> lwIP core = {tcp, udp, icmp, arp, ip}
> You said you where not using tcp_*() directly. What is your way of 
> sending and receive from TCP? netconn_*()? I.e. what is your higher
> layer around the lwIP core?

And, if you are using the netconn_*() API, how are you injecting packets
received from the network into the stack?  Are you calling tcpip_input()
(which performs the synchronization), or bypassing that and going
straight to ip_input()?


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