Re: [PATCH] mac80211: partially fix skb->cb use

[Luis Carlos Cobo <luisca@cozybit.com>]

On Tue, 2008-07-29 at 13:24 +0200, Johannes Berg wrote:
> On Tue, 2008-07-29 at 13:23 +0200, Luis Carlos Cobo wrote:
> > On Tue, 2008-07-29 at 11:32 +0200, Johannes Berg wrote:
> > > This patch fixes mac80211 to not use the skb->cb over the queue step
> > > from virtual interfaces to the master. The patch also, for now,
> > > disables aggregation because that would still require requeuing,
> > > will fix that in a separate patch. There are two other places (software
> > > requeue and powersaving stations) where requeue can happen, but that is
> > > not currently used by any drivers/not possible to use respectively.
> > 
> > On net/mac80211/rx.c:ieee80211_data_to_8023() cb is used for mesh frames
> > to save the original mesh header. Then if the frame has to be forwarded,
> > the frame is queued on the virtual interface and
> > net/mac80211/tx.c:ieee80211_subif_start_xmit() expects the mesh header
> > to remain in the cb if the frame is not originally from the local host.
> > It's a different step from the one you mention, but as I understand it
> > it may suffer the same problem right?
> 
> Indeed, that cannot be done. Good point, I'd thought that case was
> different.

One of the options I was thinking about when implemented that was to do
the forwarding in what was once equivalent to ieee80211_data_to_8023()
function. Then we do not have to do 802.11->802.3->802.11 series of
conversions, and we would send the frames to be forwarded directly to
the master device, speeding up things a bit.

I think the most elegant solution would be to add a rx handler to be run
before ieee80211_data_to_8023() dealing with forwarding and sending
frames directly to the master device. Would it make sense to deal there
too with the forwarding for APs and VLAN interfaces done in
ieee80211_deliver_skb?

-- 
Luis Carlos Cobo Rus       GnuPG ID: 44019B60
cozybit Inc.