Alexei Starovoitov <alexei.starovoi...@gmail.com> wrote: > > diff --git a/net/core/dev.c b/net/core/dev.c > > index 0e7afef..802b9b9 100644 > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -3071,9 +3071,6 @@ static int __dev_queue_xmit(struct sk_buff *skb, void > > *accel_priv) > > txq = netdev_pick_tx(dev, skb, accel_priv); > > q = rcu_dereference_bh(txq->qdisc); > > > > -#ifdef CONFIG_NET_CLS_ACT > > - skb->tc_verd = SET_TC_AT(skb->tc_verd, AT_EGRESS); > > -#endif > > I don't think it's a good change. > Squeezing 4 bits into 2 by losing AT_STACK condition, imo, is wrong.
Its right, IMO. > Before ifb could differentiate AT_STACK and AT_EGRESS, but when > they're aliased we lose this information. IFB refuses to work with skbs that did not come in via mirred. So, from ifb point of view it makes no difference, G_TC_FROM+AT_STACK causes skb to be dropped and IFB doesn't care about G_TC_AT() at all. So the change is compatible: zero state == "mirred did not see this skb" -> drop > I think we shmuld keep AT_STACK, AT_INGRESS, AT_EGRESS. We have dozens of combinations that either cannot happen from concept point of view (skb is AT_EGRESS or its coming in, it can't be both logically) or because no code path uses/sets it. For G_TC_AT(), we only have two cases: egress (since everything is attached to qdisc / coming in via dev_queue_xmit thats the "normal case", and the special ingress one, which is what the new TC_AT_INGRESS state is for. The ingress case is also "special" because it can only turn back to 0 (no mirred action attached to ingress) or change to TC_FROM_INGRESS (when mirred grabs it). The existing G_TC_AT is is irrelevant for IFB since ifb is reachable only called via ndo_start_xmit so its always at egress. skb_tc_state enum just tells us what do to with the skb -- back to ingress or transmit via device. AT_STACK cannot even happen for the G_TC_AT case from looking at the code since dev_queue_xmit forces AT_EGRESS & rx sets AT_INGRESS. And for FROM its only relevant in ifb to detect skb that wasn't seen by mirred. And we keep this functionality via 0 skb_tc_state. I did a test patch with Jamals suggestion (continue using macros, just close holes), but I see no gain: we get 5 bits that are used for automaton that only has/cares about 4 possible (distinct) skb states. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
