Re: [PATCH 6/6] net: move qdisc ingress filtering on top of netfilter ingress hooks

Alexei Starovoitov
2015-04-30T06:02:57Z

On Thu, Apr 30, 2015 at 06:05:37AM +0200, Patrick McHardy wrote:

> 06:05:37AM

do you ever sleep? ;)

> For the sake of completeness - on ingress, this alternativ means simply
> ditching TC.

I'm sure 'ditching TC' doesn't mean to kill ingress qdisc
completely. Compatibility needs to be preserved.

What I'm doing in my 'experimental ingress qdisc' acceleration
boils down to:
@@ -1649,6 +1649,7 @@ struct net_device {
rx_handler_func_t __rcu *rx_handler;
void __rcu *rx_handler_data;

- struct netdev_queue __rcu *ingress_queue;
+ struct tcf_proto __rcu *ingress_filter_list;

so to call tc_classify() and reach cls_bpf I don't need to walk
down skb->dev->ingress_queue->qdisc->enqueue/qdisc_priv->filter_list
and can just do skb->dev->ingress_filter_list
and can skip several unnecessary deref like sch->stab, skb->len, etc.
Both ingress_queue and ingress qdisc are no longer allocated
and stay only as a shim to preserve uapi.

My point is that I agree that cleanup of ingress qdisc is needed.
I disagree with drastic measures.
Just add your nf_hook to ingress and let's see how things evolve.
We have rx_handler and all of ptype hooks in there. One can argue
that rx_handler overlaps with nf_hook too ? ;)
We cannot generalize them all under one 'hook' infra.
nf needs to do nf_hook_state_init() and pass it around which
no one else needs. That's the cost others should not pay.