[PATCH net-next v2 2/3] net/sched: cls_api: Expose tc block ports to the datapath

[Victor Nogueira <victor@mojatatu.com>]

The datapath can now find the block of the port in which the packet arrived
at. It can then use it for various activities.

In the next patch we show a simple action that multicasts to all ports
excep for the port in which the packet arrived on.

Co-developed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Co-developed-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Victor Nogueira <victor@mojatatu.com>
---
 include/net/sch_generic.h |  4 ++++
 net/sched/cls_api.c       | 10 +++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 824a0ecb5afc..c5defb166ef6 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -440,6 +440,8 @@ struct qdisc_skb_cb {
 	};
 #define QDISC_CB_PRIV_LEN 20
 	unsigned char		data[QDISC_CB_PRIV_LEN];
+	/* This should allow eBPF to continue to align */
+	u32                     block_index;
 };
 
 typedef void tcf_chain_head_change_t(struct tcf_proto *tp_head, void *priv);
@@ -488,6 +490,8 @@ struct tcf_block {
 	struct mutex proto_destroy_lock; /* Lock for proto_destroy hashtable. */
 };
 
+struct tcf_block *tcf_block_lookup(struct net *net, u32 block_index);
+
 static inline bool lockdep_tcf_chain_is_locked(struct tcf_chain *chain)
 {
 	return lockdep_is_held(&chain->filter_chain_lock);
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index a976792ef02f..00e776cdd3fc 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1011,12 +1011,13 @@ static struct tcf_block *tcf_block_create(struct net *net, struct Qdisc *q,
 	return block;
 }
 
-static struct tcf_block *tcf_block_lookup(struct net *net, u32 block_index)
+struct tcf_block *tcf_block_lookup(struct net *net, u32 block_index)
 {
 	struct tcf_net *tn = net_generic(net, tcf_net_id);
 
 	return idr_find(&tn->idr, block_index);
 }
+EXPORT_SYMBOL(tcf_block_lookup);
 
 static struct tcf_block *tcf_block_refcnt_get(struct net *net, u32 block_index)
 {
@@ -1737,9 +1738,13 @@ int tcf_classify(struct sk_buff *skb,
 		 const struct tcf_proto *tp,
 		 struct tcf_result *res, bool compat_mode)
 {
+	struct qdisc_skb_cb *qdisc_cb = qdisc_skb_cb(skb);
+
 #if !IS_ENABLED(CONFIG_NET_TC_SKB_EXT)
 	u32 last_executed_chain = 0;
 
+	qdisc_cb->block_index = block ? block->index : 0;
+
 	return __tcf_classify(skb, tp, tp, res, compat_mode, NULL, 0,
 			      &last_executed_chain);
 #else
@@ -1751,6 +1756,7 @@ int tcf_classify(struct sk_buff *skb,
 	int ret;
 
 	if (block) {
+		qdisc_cb->block_index = block->index;
 		ext = skb_ext_find(skb, TC_SKB_EXT);
 
 		if (ext && (ext->chain || ext->act_miss)) {
@@ -1778,6 +1784,8 @@ int tcf_classify(struct sk_buff *skb,
 			tp = rcu_dereference_bh(fchain->filter_chain);
 			last_executed_chain = fchain->index;
 		}
+	} else {
+		qdisc_cb->block_index = 0;
 	}
 
 	ret = __tcf_classify(skb, tp, orig_tp, res, compat_mode, n, act_index,
-- 
2.25.1