hi Suvidh,
have u tried it by removing line and compiling kernel? i am also surprised. do u know any more information about how it is working?
regards,
parag
On Tue, 06 Jul 2004 Suvidh Mathur wrote :
>Hi Parag,
>
>I'm surprised that ICMP & UDP work!
>
>Look at ip_rcv(), the first statement in that is:
>struct iphdr *iph = skb->nh.iph;
>
>If you remove the skb->h.raw = skb->nh.raw = skb->data; then
>skb->nh.iph would be invalid. The assignment of pointers contained
>in skb->nh union is done by the statement in question.
>
>
>Thanks & regards,
>Suvidh Mathur
>
>
>-----Original Message-----
> From: bunty [mailto:bunty123_4@rediffmail.com]
>Sent: Sunday, July 04, 2004 8:12 PM
>To: Suvidh Mathur
>Cc: kernelnewbies@nl.linux.org
>Subject: Re: RE: how packet stored in skb?
>
>
>Hi Suvidh,
> Can you tell mw waht is the effect then if i remove the statement
>skb->h.raw = skb->nh.raw = skb->data;
>in dev.c file in net_receive_skb function?
>cause if i do that icmp and udp packet still travels on loopback but tcp will hangs kernel?
>help me understanding this.
>regards,
>parag.
>
>
>
>On Fri, 02 Jul 2004 Suvidh Mathur wrote :
> >Hi,
> >
> >I'm not sure what you mean by packet already mapped to skb?
> >
> >skb->data points to the start of unprocessed data, in netif_rx()
> >this would be the start of network layer header.
> >Another thing to notice is, h & nh are unions, so I can transparently
> >assign skb->nh.raw without bothering to figure out the actual network
> >protocol of the packet. The protocol's receive function can then use the
> >corresponding field in nh. Same goes for h.raw too, if you look closely,
> >you'd see that ip_local_deliver_finish() updates h.raw to point to skb->data
> >which would point to the unprocessed packet (read transport header).
> >
> >HTH
> >
> >Thanks & regards,
> >Suvidh Mathur
> >
> >-----Original Message-----
> > From: bunty [mailto:bunty123_4@rediffmail.com]
> >Sent: Friday, July 02, 2004 2:18 PM
> >To: kernelnewbies@nl.linux.org
> >Cc: michf@post.tau.ac.il; mohanlal@samsung.com
> >Subject: how packet stored in skb?
> >
> > hello,
> >
> >
> >why is it neccessary to copy skb->data to skb->h.raw and skb->nh.raw in dev.c file?
> >I think the whole packet structure along with data and all headers are already mapped to skb structure and after receiving packet i think no function is using raw variables to process packet they only get values from skb structure.
> >regards,
> >parag.
> >
> >
> >
>
>
>
>
>--
>Kernelnewbies: Help each other learn about the Linux kernel.
>Archive: http://mail.nl.linux.org/kernelnewbies/
>FAQ: http://kernelnewbies.org/faq/
>
