net: dsa: add tagging ops to port

The DSA tagging protocol operations are specific to each CPU port,
thus the dsa_device_ops pointer belongs to the dsa_port structure.

>From now on assign a slave's xmit copy from its CPU port tagging
operations. This will ease the future support for multiple CPU ports.

Also keep the tag_ops at the beginning of the dsa_port structure so that
we ensure copies for hot path are in cacheline 1.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -175,6 +175,9 @@ struct dsa_mall_tc_entry {
 
 
 struct dsa_port {
+	/* CPU port tagging operations used by master or slave devices */
+	const struct dsa_device_ops *tag_ops;
+
 	struct dsa_switch	*ds;
 	unsigned int		index;
 	const char		*name;

net/dsa/dsa2.c

@@ -522,6 +522,7 @@ static int dsa_cpu_parse(struct dsa_port *port, u32 index,
 		return PTR_ERR(tag_ops);
 	}
 
+	dst->cpu_dp->tag_ops = tag_ops;
 	dst->tag_ops = tag_ops;
 	dst->rcv = dst->tag_ops->rcv;
 

net/dsa/dsa_priv.h

@@ -66,7 +66,7 @@ struct dsa_notifier_vlan_info {
 };
 
 struct dsa_slave_priv {
-	/* Copy of dp->ds->dst->tag_ops->xmit for faster access in hot path */
+	/* Copy of CPU port xmit for faster access in slave transmit hot path */
 	struct sk_buff *	(*xmit)(struct sk_buff *skb,
 					struct net_device *dev);
 

net/dsa/legacy.c

@@ -152,6 +152,7 @@ static int dsa_switch_setup_one(struct dsa_switch *ds,
 		if (IS_ERR(tag_ops))
 			return PTR_ERR(tag_ops);
 
+		dst->cpu_dp->tag_ops = tag_ops;
 		dst->tag_ops = tag_ops;
 		dst->rcv = dst->tag_ops->rcv;
 	}

net/dsa/slave.c

@@ -1117,7 +1117,6 @@ int dsa_slave_resume(struct net_device *slave_dev)
 int dsa_slave_create(struct dsa_port *port, const char *name)
 {
 	struct dsa_switch *ds = port->ds;
-	struct dsa_switch_tree *dst = ds->dst;
 	struct net_device *master;
 	struct net_device *slave_dev;
 	struct dsa_slave_priv *p;
@@ -1162,7 +1161,7 @@ int dsa_slave_create(struct dsa_port *port, const char *name)
 	}
 	p->dp = port;
 	INIT_LIST_HEAD(&p->mall_tc_list);
-	p->xmit = dst->tag_ops->xmit;
+	p->xmit = cpu_dp->tag_ops->xmit;
 
 	p->old_pause = -1;
 	p->old_link = -1;