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?
_This_ is the issue now that really concerns me.
Later,
David S. Miller
davem@xxxxxxxxxx
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