[NET_SCHED]: act_api: qdisc internal reclassify support

The behaviour of NET_CLS_POLICE for TC_POLICE_RECLASSIFY was to return
it to the qdisc, which could handle it internally or ignore it. With
NET_CLS_ACT however, tc_classify starts over at the first classifier
and never returns it to the qdisc. This makes it impossible to support
qdisc-internal reclassification, which in turn makes it impossible to
remove the old NET_CLS_POLICE code without breaking compatibility since
we have two qdiscs (CBQ and ATM) that support this.

This patch adds a tc_classify_compat function that handles
reclassification the old way and changes CBQ and ATM to use it.

This again is of course not fully backwards compatible with the previous
NET_CLS_ACT behaviour. Unfortunately there is no way to fully maintain
compatibility *and* support qdisc internal reclassification with
NET_CLS_ACT, but this seems like the better choice over keeping the two
incompatible options around forever.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 2 deletions

diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c
index ccee10dae66d..37ae6d1deb14 100644
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -396,8 +396,9 @@ static int atm_tc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
             !(flow = (struct atm_flow_data *)atm_tc_get(sch, skb->priority)))
                 for (flow = p->flows; flow; flow = flow->next)
                         if (flow->filter_list) {
-                                result = tc_classify(skb, flow->filter_list,
-                                                     &res);
+                                result = tc_classify_compat(skb,
+                                                            flow->filter_list,
+                                                            &res);
                                 if (result < 0)
                                         continue;
                                 flow = (struct atm_flow_data *)res.class;
@@ -420,6 +421,12 @@ static int atm_tc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
                 case TC_ACT_SHOT:
                         kfree_skb(skb);
                         goto drop;
+                case TC_POLICE_RECLASSIFY:
+                        if (flow->excess)
+                                flow = flow->excess;
+                        else
+                                ATM_SKB(skb)->atm_options |= ATM_ATMOPT_CLP;
+                        break;
                 }
 #elif defined(CONFIG_NET_CLS_POLICE)
                 switch (result) {