net: dsa: Add overhead to tag protocol ops.

Each DSA tag protocol needs to add additional headers to the Ethernet
frame in order to direct it towards a specific switch egress port. It
must also remove the head from a frame received from a
switch. Indicate the maximum size of these headers in the tag protocol
ops structure, so the core can take these overheads into account.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -113,6 +113,7 @@ struct dsa_device_ops {
 			       struct packet_type *pt);
 	int (*flow_dissect)(const struct sk_buff *skb, __be16 *proto,
 			    int *offset);
+	unsigned int overhead;
 };
 
 struct dsa_switch_tree {

net/dsa/tag_brcm.c

@@ -174,6 +174,7 @@ static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 const struct dsa_device_ops brcm_netdev_ops = {
 	.xmit	= brcm_tag_xmit,
 	.rcv	= brcm_tag_rcv,
+	.overhead = BRCM_TAG_LEN,
 };
 #endif
 
@@ -196,5 +197,6 @@ static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
 const struct dsa_device_ops brcm_prepend_netdev_ops = {
 	.xmit	= brcm_tag_xmit_prepend,
 	.rcv	= brcm_tag_rcv_prepend,
+	.overhead = BRCM_TAG_LEN,
 };
 #endif

net/dsa/tag_dsa.c

@@ -149,4 +149,5 @@ static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
 const struct dsa_device_ops dsa_netdev_ops = {
 	.xmit	= dsa_xmit,
 	.rcv	= dsa_rcv,
+	.overhead = DSA_HLEN,
 };

net/dsa/tag_edsa.c

@@ -168,4 +168,5 @@ static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
 const struct dsa_device_ops edsa_netdev_ops = {
 	.xmit	= edsa_xmit,
 	.rcv	= edsa_rcv,
+	.overhead = EDSA_HLEN,
 };

net/dsa/tag_gswip.c

@@ -106,4 +106,5 @@ static struct sk_buff *gswip_tag_rcv(struct sk_buff *skb,
 const struct dsa_device_ops gswip_netdev_ops = {
 	.xmit = gswip_tag_xmit,
 	.rcv = gswip_tag_rcv,
+	.overhead = GSWIP_RX_HEADER_LEN,
 };

net/dsa/tag_ksz.c

@@ -99,4 +99,5 @@ static struct sk_buff *ksz_rcv(struct sk_buff *skb, struct net_device *dev,
 const struct dsa_device_ops ksz_netdev_ops = {
 	.xmit	= ksz_xmit,
 	.rcv	= ksz_rcv,
+	.overhead = KSZ_INGRESS_TAG_LEN,
 };

net/dsa/tag_lan9303.c

@@ -140,4 +140,5 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 const struct dsa_device_ops lan9303_netdev_ops = {
 	.xmit = lan9303_xmit,
 	.rcv = lan9303_rcv,
+	.overhead = LAN9303_TAG_LEN,
 };

net/dsa/tag_mtk.c

@@ -109,4 +109,5 @@ const struct dsa_device_ops mtk_netdev_ops = {
 	.xmit		= mtk_tag_xmit,
 	.rcv		= mtk_tag_rcv,
 	.flow_dissect	= mtk_tag_flow_dissect,
+	.overhead	= MTK_HDR_LEN,
 };

net/dsa/tag_qca.c

@@ -101,4 +101,5 @@ static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 const struct dsa_device_ops qca_netdev_ops = {
 	.xmit	= qca_tag_xmit,
 	.rcv	= qca_tag_rcv,
+	.overhead = QCA_HDR_LEN,
 };

net/dsa/tag_trailer.c

@@ -84,4 +84,5 @@ static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev,
 const struct dsa_device_ops trailer_netdev_ops = {
 	.xmit	= trailer_xmit,
 	.rcv	= trailer_rcv,
+	.overhead = 4,
 };