With all this talk of the CB field. What is the correct way to use the CB
field when implementing a new protocol?
Thanks,
Jim
On Tue, Apr 25, 2000 at 02:01:35AM +0200, Andi Kleen wrote:
> On Tue, Apr 25, 2000 at 01:53:51AM +0200, David S. Miller wrote:
> > Date: Tue, 25 Apr 2000 01:50:08 +0200
> > From: Andi Kleen <ak@xxxxxx>
> >
> > > I know intuitively that once, for example, tcp_transmit_skb has
> > > built the TCP header the control block can be clobbered by any
> > > further usage. We should really document this, at least in a
> > > comment above that function.
> >
> > I documented it in skbuff.h (``is owned by whoever has the skb queued'')
> >
> > BTW, the hippi private fields should be probably moved there too.
> >
> > This brings up an important issue. What if then, we'd like to shape
> > packets over HIPPI? It sounds really stupid, I know, but the point
> > is that once we start allowing software or hardware devices to use the
> > CB for their private per-packet state, we can run into problems if one
> > is a pseudo device in front of another.
> >
> > If shaper mucks with it's CB fields, and once it has sent the packet
> > off to the real device it never references that skb header again, then
> > at least in this case there is no problem. Is that what is happening
> > here?
> >
> Not a problem. Shaper calls skb_clone before submitting the data.
>
>
> -Andi
>
> --
> This is like TV. I don't like TV.
--
James R. Leu
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