netdev - [PATCH net-next v3 2/3] net/sched: cls_api: Expose tc block to the datapath

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Date: Mon, 11 Sep 2023 20:27:48 -0300
From: Victor Nogueira <victor@...atatu.com>
To: jhs@...atatu.com,
	xiyou.wangcong@...il.com,
	jiri@...nulli.us,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com
Cc: mleitner@...hat.com,
	vladbu@...dia.com,
	horms@...nel.org,
	pctammela@...atatu.com,
	netdev@...r.kernel.org,
	kernel@...atatu.com
Subject: [PATCH net-next v3 2/3] net/sched: cls_api: Expose tc block to the datapath

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
except for the port in which the packet arrived on.

Co-developed-by: Jamal Hadi Salim <jhs@...atatu.com>
Signed-off-by: Jamal Hadi Salim <jhs@...atatu.com>
Co-developed-by: Pedro Tammela <pctammela@...atatu.com>
Signed-off-by: Pedro Tammela <pctammela@...atatu.com>
Signed-off-by: Victor Nogueira <victor@...atatu.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 f002b0423efc..a99ac60426b3 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 06b55344a948..c102fe26ac5e 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -1012,12 +1012,13 @@ 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)
 {
@@ -1738,9 +1739,13 @@ 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
@@ -1752,6 +1757,7 @@ 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)) {
@@ -1779,6 +1785,8 @@ 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