[net-next RFC PATCH v2 1/8] net: das: Introduce support for tagger private data control

[Ansuel Smith <ansuelsmth@gmail.com>]

Introduce 2 new function for the tagger ops to permit the tagger to
allocate private data. This is useful for case where the tagger receive
some data that should be by the switch driver or require some special
handling for some special packet (example Ethernet mdio packet)

The tagger will use the dsa port priv to store his priv data.

connect() is used to allocate the private data. It's the tagger choice
how to allocate the data to the different ports.
disconnect() will free the priv data in the dsa port.

On switch setup the connect() ops is called.
On tagger change the disconnect() is called, the tagger will free the
priv data in dsa port and a connect() is called to allocate the new priv
data (if the new tagger requires it)

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
 include/net/dsa.h |  3 +++
 net/dsa/dsa2.c    | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 8ca9d50cbbc2..33391d74be5c 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -82,8 +82,11 @@ enum dsa_tag_protocol {
 };
 
 struct dsa_switch;
+struct dsa_switch_tree;
 
 struct dsa_device_ops {
+	int (*connect)(struct dsa_switch_tree *dst);
+	void (*disconnect)(struct dsa_switch_tree *dst);
 	struct sk_buff *(*xmit)(struct sk_buff *skb, struct net_device *dev);
 	struct sk_buff *(*rcv)(struct sk_buff *skb, struct net_device *dev);
 	void (*flow_dissect)(const struct sk_buff *skb, __be16 *proto,
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 826957b6442b..15566c5ae8ae 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -1043,6 +1043,20 @@ static void dsa_tree_teardown_lags(struct dsa_switch_tree *dst)
 	kfree(dst->lags);
 }
 
+static int dsa_tree_bind_tag_proto(struct dsa_switch_tree *dst)
+{
+	const struct dsa_device_ops *tag_ops = dst->tag_ops;
+	int err;
+
+	if (tag_ops->connect) {
+		err = tag_ops->connect(dst);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 static int dsa_tree_setup(struct dsa_switch_tree *dst)
 {
 	bool complete;
@@ -1066,6 +1080,10 @@ static int dsa_tree_setup(struct dsa_switch_tree *dst)
 	if (err)
 		goto teardown_cpu_ports;
 
+	err = dsa_tree_bind_tag_proto(dst);
+	if (err)
+		goto teardown_switches;
+
 	err = dsa_tree_setup_master(dst);
 	if (err)
 		goto teardown_switches;
@@ -1155,13 +1173,21 @@ int dsa_tree_change_tag_proto(struct dsa_switch_tree *dst,
 	if (err)
 		goto out_unwind_tagger;
 
+	if (dst->tag_ops->disconnect)
+		dst->tag_ops->disconnect(dst);
+
 	dst->tag_ops = tag_ops;
 
+	err = dsa_tree_bind_tag_proto(dst);
+	if (err)
+		goto out_unwind_tagger;
+
 	rtnl_unlock();
 
 	return 0;
 
 out_unwind_tagger:
+	dst->tag_ops = old_tag_ops;
 	info.tag_ops = old_tag_ops;
 	dsa_tree_notify(dst, DSA_NOTIFIER_TAG_PROTO, &info);
 out_unlock:
-- 
2.32.0