Merge branch 'dsa_ptr-port'

Vivien Didelot says:

====================
net: dsa: change dsa_ptr for a dsa_port

With DSA, a master net_device is physically wired to a dedicated CPU
switch port. For interaction with the DSA layer, the struct net_device
contains a dsa_ptr, which currently points to a dsa_switch_tree object.

This is only valid for a switch fabric with a single CPU port. In order
to support switch fabrics with multiple CPU ports, we first need to
change the type of dsa_ptr to what it really is: a dsa_port object.

This is what this patchset does. The first patches adds a
dsa_master_get_slave helper and cleans up portions of DSA core to make
the next patches more readable. These next patches prepare the xmit and
receive hot paths and finally change dsa_ptr.

Changes in v2:
  - introduce dsa_master_get_slave helper to simplify patch 6
  - keep hot path data at beginning of dsa_port for cacheline 1
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

16 files changed, 97 insertions, 155 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f535779d9dc1..e1d6ef130611 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -55,7 +55,7 @@
 struct netpoll_info;
 struct device;
 struct phy_device;
-struct dsa_switch_tree;
+struct dsa_port;
 
 /* 802.11 specific */
 struct wireless_dev;
@@ -1752,7 +1752,7 @@ struct net_device {
 	struct vlan_info __rcu	*vlan_info;
 #endif
 #if IS_ENABLED(CONFIG_NET_DSA)
-	struct dsa_switch_tree	*dsa_ptr;
+	struct dsa_port		*dsa_ptr;
 #endif
 #if IS_ENABLED(CONFIG_TIPC)
 	struct tipc_bearer __rcu *tipc_ptr;
diff --git a/include/net/dsa.h b/include/net/dsa.h
index 8dee216a5a9b..10dceccd9ce8 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -130,11 +130,6 @@ struct dsa_switch_tree {
 	 */
 	struct dsa_platform_data	*pd;
 
-	/* Copy of tag_ops->rcv for faster access in hot path */
-	struct sk_buff *	(*rcv)(struct sk_buff *skb,
-				       struct net_device *dev,
-				       struct packet_type *pt);
-
 	/*
 	 * The switch port to which the CPU is attached.
 	 */
@@ -144,12 +139,6 @@ struct dsa_switch_tree {
 	 * Data for the individual switch chips.
 	 */
 	struct dsa_switch	*ds[DSA_MAX_SWITCHES];
-
-	/*
-	 * Tagging protocol operations for adding and removing an
-	 * encapsulation tag.
-	 */
-	const struct dsa_device_ops *tag_ops;
 };
 
 /* TC matchall action types, only mirroring for now */
@@ -175,6 +164,14 @@ 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;
+
+	/* Copies for faster access in master receive hot path */
+	struct dsa_switch_tree *dst;
+	struct sk_buff *(*rcv)(struct sk_buff *skb, struct net_device *dev,
+			       struct packet_type *pt);
+
 	struct dsa_switch	*ds;
 	unsigned int		index;
 	const char		*name;
diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 81c852e32821..51ca2a524a27 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -160,12 +160,12 @@ EXPORT_SYMBOL_GPL(dsa_dev_to_net_device);
 static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
 			  struct packet_type *pt, struct net_device *unused)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
 	struct sk_buff *nskb = NULL;
 	struct pcpu_sw_netstats *s;
 	struct dsa_slave_priv *p;
 
-	if (unlikely(dst == NULL)) {
+	if (unlikely(!cpu_dp)) {
 		kfree_skb(skb);
 		return 0;
 	}
@@ -174,7 +174,7 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
 	if (!skb)
 		return 0;
 
-	nskb = dst->rcv(skb, dev, pt);
+	nskb = cpu_dp->rcv(skb, dev, pt);
 	if (!nskb) {
 		kfree_skb(skb);
 		return 0;
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index dcccaebde708..54ed054777bd 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -438,7 +438,7 @@ static int dsa_dst_apply(struct dsa_switch_tree *dst)
 	 * sent to the tag format's receive function.
 	 */
 	wmb();
-	dst->cpu_dp->netdev->dsa_ptr = dst;
+	dst->cpu_dp->netdev->dsa_ptr = dst->cpu_dp;
 
 	err = dsa_master_ethtool_setup(dst->cpu_dp->netdev);
 	if (err)
@@ -485,6 +485,7 @@ static int dsa_cpu_parse(struct dsa_port *port, u32 index,
 			 struct dsa_switch_tree *dst,
 			 struct dsa_switch *ds)
 {
+	const struct dsa_device_ops *tag_ops;
 	enum dsa_tag_protocol tag_protocol;
 	struct net_device *ethernet_dev;
 	struct device_node *ethernet;
@@ -514,14 +515,18 @@ static int dsa_cpu_parse(struct dsa_port *port, u32 index,
 	ds->cpu_port_mask |= BIT(index);
 
 	tag_protocol = ds->ops->get_tag_protocol(ds);
-	dst->tag_ops = dsa_resolve_tag_protocol(tag_protocol);
-	if (IS_ERR(dst->tag_ops)) {
+	tag_ops = dsa_resolve_tag_protocol(tag_protocol);
+	if (IS_ERR(tag_ops)) {
 		dev_warn(ds->dev, "No tagger for this switch\n");
 		ds->cpu_port_mask &= ~BIT(index);
-		return PTR_ERR(dst->tag_ops);
+		return PTR_ERR(tag_ops);
 	}
 
-	dst->rcv = dst->tag_ops->rcv;
+	dst->cpu_dp->tag_ops = tag_ops;
+
+	/* Make a few copies for faster access in master receive hot path */
+	dst->cpu_dp->rcv = dst->cpu_dp->tag_ops->rcv;
+	dst->cpu_dp->dst = dst;
 
 	return 0;
 }
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index eccc62776283..2850077cc9cc 100644
--- a/net/dsa/dsa_priv.h
+++ b/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);
 
@@ -113,6 +113,26 @@ int dsa_legacy_fdb_del(struct ndmsg *ndm, struct nlattr *tb[],
 int dsa_master_ethtool_setup(struct net_device *dev);
 void dsa_master_ethtool_restore(struct net_device *dev);
 
+static inline struct net_device *dsa_master_get_slave(struct net_device *dev,
+						      int device, int port)
+{
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
+	struct dsa_switch_tree *dst = cpu_dp->dst;
+	struct dsa_switch *ds;
+
+	if (device < 0 || device >= DSA_MAX_SWITCHES)
+		return NULL;
+
+	ds = dst->ds[device];
+	if (!ds)
+		return NULL;
+
+	if (port < 0 || port >= ds->num_ports)
+		return NULL;
+
+	return ds->ports[port].netdev;
+}
+
 /* port.c */
 int dsa_port_set_state(struct dsa_port *dp, u8 state,
 		       struct switchdev_trans *trans);
@@ -182,9 +202,4 @@ static inline struct net_device *dsa_master_netdev(struct dsa_slave_priv *p)
 	return p->dp->cpu_dp->netdev;
 }
 
-static inline struct dsa_port *dsa_get_cpu_port(struct dsa_switch_tree *dst)
-{
-	return dst->cpu_dp;
-}
-
 #endif
diff --git a/net/dsa/legacy.c b/net/dsa/legacy.c
index ae505d8e4417..19ff6e0a21dc 100644
--- a/net/dsa/legacy.c
+++ b/net/dsa/legacy.c
@@ -144,14 +144,19 @@ static int dsa_switch_setup_one(struct dsa_switch *ds,
 	 * switch.
 	 */
 	if (dst->cpu_dp->ds == ds) {
+		const struct dsa_device_ops *tag_ops;
 		enum dsa_tag_protocol tag_protocol;
 
 		tag_protocol = ops->get_tag_protocol(ds);
-		dst->tag_ops = dsa_resolve_tag_protocol(tag_protocol);
-		if (IS_ERR(dst->tag_ops))
-			return PTR_ERR(dst->tag_ops);
+		tag_ops = dsa_resolve_tag_protocol(tag_protocol);
+		if (IS_ERR(tag_ops))
+			return PTR_ERR(tag_ops);
 
-		dst->rcv = dst->tag_ops->rcv;
+		dst->cpu_dp->tag_ops = tag_ops;
+
+		/* Few copies for faster access in master receive hot path */
+		dst->cpu_dp->rcv = dst->cpu_dp->tag_ops->rcv;
+		dst->cpu_dp->dst = dst;
 	}
 
 	memcpy(ds->rtable, cd->rtable, sizeof(ds->rtable));
@@ -600,7 +605,7 @@ static int dsa_setup_dst(struct dsa_switch_tree *dst, struct net_device *dev,
 	 * sent to the tag format's receive function.
 	 */
 	wmb();
-	dev->dsa_ptr = dst;
+	dev->dsa_ptr = dst->cpu_dp;
 
 	return dsa_master_ethtool_setup(dst->cpu_dp->netdev);
 }
diff --git a/net/dsa/master.c b/net/dsa/master.c
index 5e5147ec5a44..5f3f57e372e0 100644
--- a/net/dsa/master.c
+++ b/net/dsa/master.c
@@ -16,10 +16,10 @@ static void dsa_master_get_ethtool_stats(struct net_device *dev,
 					 struct ethtool_stats *stats,
 					 uint64_t *data)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *port = dst->cpu_dp;
-	struct dsa_switch *ds = port->ds;
-	const struct ethtool_ops *ops = port->orig_ethtool_ops;
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
+	const struct ethtool_ops *ops = cpu_dp->orig_ethtool_ops;
+	struct dsa_switch *ds = cpu_dp->ds;
+	int port = cpu_dp->index;
 	int count = 0;
 
 	if (ops && ops->get_sset_count && ops->get_ethtool_stats) {
@@ -28,15 +28,14 @@ static void dsa_master_get_ethtool_stats(struct net_device *dev,
 	}
 
 	if (ds->ops->get_ethtool_stats)
-		ds->ops->get_ethtool_stats(ds, port->index, data + count);
+		ds->ops->get_ethtool_stats(ds, port, data + count);
 }
 
 static int dsa_master_get_sset_count(struct net_device *dev, int sset)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *port = dst->cpu_dp;
-	struct dsa_switch *ds = port->ds;
-	const struct ethtool_ops *ops = port->orig_ethtool_ops;
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
+	const struct ethtool_ops *ops = cpu_dp->orig_ethtool_ops;
+	struct dsa_switch *ds = cpu_dp->ds;
 	int count = 0;
 
 	if (ops && ops->get_sset_count)
@@ -51,17 +50,17 @@ static int dsa_master_get_sset_count(struct net_device *dev, int sset)
 static void dsa_master_get_strings(struct net_device *dev, uint32_t stringset,
 				   uint8_t *data)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *port = dst->cpu_dp;
-	struct dsa_switch *ds = port->ds;
-	const struct ethtool_ops *ops = port->orig_ethtool_ops;
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
+	const struct ethtool_ops *ops = cpu_dp->orig_ethtool_ops;
+	struct dsa_switch *ds = cpu_dp->ds;
+	int port = cpu_dp->index;
 	int len = ETH_GSTRING_LEN;
 	int mcount = 0, count;
 	unsigned int i;
 	uint8_t pfx[4];
 	uint8_t *ndata;
 
-	snprintf(pfx, sizeof(pfx), "p%.2d", port->index);
+	snprintf(pfx, sizeof(pfx), "p%.2d", port);
 	/* We do not want to be NULL-terminated, since this is a prefix */
 	pfx[sizeof(pfx) - 1] = '_';
 
@@ -76,7 +75,7 @@ static void dsa_master_get_strings(struct net_device *dev, uint32_t stringset,
 		 * the output after to prepend our CPU port prefix we
 		 * constructed earlier
 		 */
-		ds->ops->get_strings(ds, port->index, ndata);
+		ds->ops->get_strings(ds, port, ndata);
 		count = ds->ops->get_sset_count(ds);
 		for (i = 0; i < count; i++) {
 			memmove(ndata + (i * len + sizeof(pfx)),
@@ -88,18 +87,17 @@ static void dsa_master_get_strings(struct net_device *dev, uint32_t stringset,
 
 int dsa_master_ethtool_setup(struct net_device *dev)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *port = dst->cpu_dp;
-	struct dsa_switch *ds = port->ds;
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
+	struct dsa_switch *ds = cpu_dp->ds;
 	struct ethtool_ops *ops;
 
 	ops = devm_kzalloc(ds->dev, sizeof(*ops), GFP_KERNEL);
 	if (!ops)
 		return -ENOMEM;
 
-	port->orig_ethtool_ops = dev->ethtool_ops;
-	if (port->orig_ethtool_ops)
-		memcpy(ops, port->orig_ethtool_ops, sizeof(*ops));
+	cpu_dp->orig_ethtool_ops = dev->ethtool_ops;
+	if (cpu_dp->orig_ethtool_ops)
+		memcpy(ops, cpu_dp->orig_ethtool_ops, sizeof(*ops));
 
 	ops->get_sset_count = dsa_master_get_sset_count;
 	ops->get_ethtool_stats = dsa_master_get_ethtool_stats;
@@ -112,9 +110,8 @@ int dsa_master_ethtool_setup(struct net_device *dev)
 
 void dsa_master_ethtool_restore(struct net_device *dev)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *port = dst->cpu_dp;
+	struct dsa_port *cpu_dp = dev->dsa_ptr;
 
-	dev->ethtool_ops = port->orig_ethtool_ops;
-	port->orig_ethtool_ops = NULL;
+	dev->ethtool_ops = cpu_dp->orig_ethtool_ops;
+	cpu_dp->orig_ethtool_ops = NULL;
 }
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index bf8800de13c1..4b634db05cee 100644
--- a/net/dsa/slave.c
+++ b/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;
diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
index dbb016434ace..8e4bdb9d9ae3 100644
--- a/net/dsa/tag_brcm.c
+++ b/net/dsa/tag_brcm.c
@@ -92,9 +92,6 @@ static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb, struct net_device *dev
 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 				    struct packet_type *pt)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *cpu_dp = dsa_get_cpu_port(dst);
-	struct dsa_switch *ds = cpu_dp->ds;
 	int source_port;
 	u8 *brcm_tag;
 
@@ -117,8 +114,8 @@ static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 	/* Locate which port this is coming from */
 	source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
 
-	/* Validate port against switch setup, either the port is totally */
-	if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
+	skb->dev = dsa_master_get_slave(dev, 0, source_port);
+	if (!skb->dev)
 		return NULL;
 
 	/* Remove Broadcom tag and update checksum */
@@ -129,8 +126,6 @@ static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 		skb->data - ETH_HLEN - BRCM_TAG_LEN,
 		2 * ETH_ALEN);
 
-	skb->dev = ds->ports[source_port].netdev;
-
 	return skb;
 }
 
diff --git a/net/dsa/tag_dsa.c b/net/dsa/tag_dsa.c
index fbf9ca954773..c77218f173d1 100644
--- a/net/dsa/tag_dsa.c
+++ b/net/dsa/tag_dsa.c
@@ -67,8 +67,6 @@ static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
 static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
 			       struct packet_type *pt)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_switch *ds;
 	u8 *dsa_header;
 	int source_device;
 	int source_port;
@@ -93,18 +91,8 @@ static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
 	source_device = dsa_header[0] & 0x1f;
 	source_port = (dsa_header[1] >> 3) & 0x1f;
 
-	/*
-	 * Check that the source device exists and that the source
-	 * port is a registered DSA port.
-	 */
-	if (source_device >= DSA_MAX_SWITCHES)
-		return NULL;
-
-	ds = dst->ds[source_device];
-	if (!ds)
-		return NULL;
-
-	if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
+	skb->dev = dsa_master_get_slave(dev, source_device, source_port);
+	if (!skb->dev)
 		return NULL;
 
 	/*
@@ -153,8 +141,6 @@ static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
 			2 * ETH_ALEN);
 	}
 
-	skb->dev = ds->ports[source_port].netdev;
-
 	return skb;
 }
 
diff --git a/net/dsa/tag_edsa.c b/net/dsa/tag_edsa.c
index 76367ba1b2e2..0b83cbe0c9e8 100644
--- a/net/dsa/tag_edsa.c
+++ b/net/dsa/tag_edsa.c
@@ -80,8 +80,6 @@ static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
 static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
 				struct packet_type *pt)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_switch *ds;
 	u8 *edsa_header;
 	int source_device;
 	int source_port;
@@ -106,18 +104,8 @@ static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
 	source_device = edsa_header[0] & 0x1f;
 	source_port = (edsa_header[1] >> 3) & 0x1f;
 
-	/*
-	 * Check that the source device exists and that the source
-	 * port is a registered DSA port.
-	 */
-	if (source_device >= DSA_MAX_SWITCHES)
-		return NULL;
-
-	ds = dst->ds[source_device];
-	if (!ds)
-		return NULL;
-
-	if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
+	skb->dev = dsa_master_get_slave(dev, source_device, source_port);
+	if (!skb->dev)
 		return NULL;
 
 	/*
@@ -172,8 +160,6 @@ static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
 			2 * ETH_ALEN);
 	}
 
-	skb->dev = ds->ports[source_port].netdev;
-
 	return skb;
 }
 
diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 010ca0a336c4..b241c990cde0 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -80,22 +80,19 @@ static struct sk_buff *ksz_xmit(struct sk_buff *skb, struct net_device *dev)
 static struct sk_buff *ksz_rcv(struct sk_buff *skb, struct net_device *dev,
 			       struct packet_type *pt)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *cpu_dp = dsa_get_cpu_port(dst);
-	struct dsa_switch *ds = cpu_dp->ds;
 	u8 *tag;
 	int source_port;
 
 	tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN;
 
 	source_port = tag[0] & 7;
-	if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
+
+	skb->dev = dsa_master_get_slave(dev, 0, source_port);
+	if (!skb->dev)
 		return NULL;
 
 	pskb_trim_rcsum(skb, skb->len - KSZ_EGRESS_TAG_LEN);
 
-	skb->dev = ds->ports[source_port].netdev;
-
 	return skb;
 }
 
diff --git a/net/dsa/tag_lan9303.c b/net/dsa/tag_lan9303.c
index 0b9826105e42..4f211e56c81f 100644
--- a/net/dsa/tag_lan9303.c
+++ b/net/dsa/tag_lan9303.c
@@ -71,17 +71,8 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 			struct packet_type *pt)
 {
 	u16 *lan9303_tag;
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_switch *ds;
 	unsigned int source_port;
 
-	ds = dst->ds[0];
-
-	if (unlikely(!ds)) {
-		dev_warn_ratelimited(&dev->dev, "Dropping packet, due to missing DSA switch device\n");
-		return NULL;
-	}
-
 	if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
 		dev_warn_ratelimited(&dev->dev,
 				     "Dropping packet, cannot pull\n");
@@ -103,16 +94,12 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 
 	source_port = ntohs(lan9303_tag[1]) & 0x3;
 
-	if (source_port >= ds->num_ports) {
+	skb->dev = dsa_master_get_slave(dev, 0, source_port);
+	if (!skb->dev) {
 		dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n");
 		return NULL;
 	}
 
-	if (!ds->ports[source_port].netdev) {
-		dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid netdev or device\n");
-		return NULL;
-	}
-
 	/* remove the special VLAN tag between the MAC addresses
 	 * and the current ethertype field.
 	 */
@@ -120,9 +107,6 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 	memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN),
 		2 * ETH_ALEN);
 
-	/* forward the packet to the dedicated interface */
-	skb->dev = ds->ports[source_port].netdev;
-
 	return skb;
 }
 
diff --git a/net/dsa/tag_mtk.c b/net/dsa/tag_mtk.c
index ec8ee5f43255..968586c5d40e 100644
--- a/net/dsa/tag_mtk.c
+++ b/net/dsa/tag_mtk.c
@@ -46,8 +46,6 @@ static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
 static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 				   struct packet_type *pt)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_switch *ds;
 	int port;
 	__be16 *phdr, hdr;
 
@@ -68,20 +66,12 @@ static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 		skb->data - ETH_HLEN - MTK_HDR_LEN,
 		2 * ETH_ALEN);
 
-	/* This protocol doesn't support cascading multiple
-	 * switches so it's safe to assume the switch is first
-	 * in the tree.
-	 */
-	ds = dst->ds[0];
-	if (!ds)
-		return NULL;
-
 	/* Get source port information */
 	port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
-	if (!ds->ports[port].netdev)
-		return NULL;
 
-	skb->dev = ds->ports[port].netdev;
+	skb->dev = dsa_master_get_slave(dev, 0, port);
+	if (!skb->dev)
+		return NULL;
 
 	return skb;
 }
diff --git a/net/dsa/tag_qca.c b/net/dsa/tag_qca.c
index 1d4c70711c0f..8d33d9ebf910 100644
--- a/net/dsa/tag_qca.c
+++ b/net/dsa/tag_qca.c
@@ -65,9 +65,6 @@ static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
 static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 				   struct packet_type *pt)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *cpu_dp = dsa_get_cpu_port(dst);
-	struct dsa_switch *ds;
 	u8 ver;
 	int port;
 	__be16 *phdr, hdr;
@@ -92,20 +89,12 @@ static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 	memmove(skb->data - ETH_HLEN, skb->data - ETH_HLEN - QCA_HDR_LEN,
 		ETH_HLEN - QCA_HDR_LEN);
 
-	/* This protocol doesn't support cascading multiple switches so it's
-	 * safe to assume the switch is first in the tree
-	 */
-	ds = cpu_dp->ds;
-	if (!ds)
-		return NULL;
-
 	/* Get source port information */
 	port = (hdr & QCA_HDR_RECV_SOURCE_PORT_MASK);
-	if (!ds->ports[port].netdev)
-		return NULL;
 
-	/* Update skb & forward the frame accordingly */
-	skb->dev = ds->ports[port].netdev;
+	skb->dev = dsa_master_get_slave(dev, 0, port);
+	if (!skb->dev)
+		return NULL;
 
 	return skb;
 }
diff --git a/net/dsa/tag_trailer.c b/net/dsa/tag_trailer.c
index d2fd4923aa3e..61668be267f5 100644
--- a/net/dsa/tag_trailer.c
+++ b/net/dsa/tag_trailer.c
@@ -58,9 +58,6 @@ static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
 static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev,
 				   struct packet_type *pt)
 {
-	struct dsa_switch_tree *dst = dev->dsa_ptr;
-	struct dsa_port *cpu_dp = dsa_get_cpu_port(dst);
-	struct dsa_switch *ds = cpu_dp->ds;
 	u8 *trailer;
 	int source_port;
 
@@ -73,13 +70,13 @@ static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev,
 		return NULL;
 
 	source_port = trailer[1] & 7;
-	if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
+
+	skb->dev = dsa_master_get_slave(dev, 0, source_port);
+	if (!skb->dev)
 		return NULL;
 
 	pskb_trim_rcsum(skb, skb->len - 4);
 
-	skb->dev = ds->ports[source_port].netdev;
-
 	return skb;
 }