Re: [lwip-users] pbuf len field equal zero

[EVS Hardware Dpt]

Christiaan,

I you look in my code you'll see that I loop until the sum of all individual len fields equals the tot_len field of the first pbuf in the chain. After your answer, I've changed it to your proposal (nicer than the one I use), but the problem is still there. In the middle of a pbuf chain I get a pbuf with a len field being 0. If I skip it, then I broke the chain and I my ISR when calling pbuf_free, I suspect that the whole chain is not freed correctly.

I have some difficulties to understand the signification of a pbuf wich len field is 0. Is it normal ? Can I simply remove this entry and rebuild the chain without it ? For example :

q = p;
while(1)
{
   if(q->next->len == 0)
   {
      q->next = q->next->next;
   }
   q = q->next
}

This code is just for illustration, if it appears that I must rebuild the chain, then there are a lot of things to double check.

Thanks,
Frederic.

2005/12/13, Christiaan Simons <address@hidden>:

lwip-users-bounces+christiaan.simons=address@hidden wrote on 12-12-2005
18:02:27:

> My question is : why do I have some pbuf with len field being 0 ? Is
> it normal, what should I do with them ?

Taken from the comment in lwip/src/core/pbuf.c

"Therefore, looping through a pbuf of a single packet, has an
loop end condition (tot_len == p->len), NOT (next == NULL)"

Maybe this helps?

Bye,

Christiaan Simons

Hardware / Software Engineer
Axon Digital Design

+31 (0)13 511 66 66
+31 (0)13 511 41 51

http://www.axon.tv


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