Re: question about the receiving ip path

From: Bernd Eckenfels (
Date: Wed Jul 17 2002 - 16:22:54 EST

In article <> you wrote:
> I would like to know if the cloned sk_buff is really needed, and also what
> is the path used, (how to find it, since it's a maze to try to figure out
> the receiving path, by looking at place where sk_buff are cloned, since I
> don't know the entry function). At least knowing the entry function could
> help a lot.

For 2.4 see net/core/dev.c:netif_rx(skb) which is called by the network
driver. This will add it to the queue->input_pkt_queue, which is processed
by net_rx_action(), which will call the protocol families receive handlers
eighter directly via the func() method of the protcol or by
deliver_to_old_cones() which does contain the clone. for ip it is
net/ipv4/ip_input.c:ip_rcv() which hands it to ip_rcv_finish() which
distributes it to the ip_local_deliver() for local targets which then passes
it to ip_local_deliver_finish() which calls the ip protocol handler, for
example udp_rcv which looks up the socket and passes it into that.

Hope this is nearly right, by reading the source. Note, I am not shure with
softirq and stuff, which function is running in the irq or bottom half mode.

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