Merge branch 'dsa-mtu'

Andrew Lunn says:

====================
Adjust MTU of DSA master interface

DSA makes use of additional headers to direct a frame in/out of a
specific port of the switch. When the slave interfaces uses an MTU of
1500, the master interface can be asked to handle frames with an MTU
of 1504, or 1508 bytes. Some Ethernet interfaces won't
transmit/receive frames which are bigger than their MTU.

Automate the increasing of the MTU on the master interface, by adding
to each tagging driver how much overhead they need, and then calling
dev_set_mtu() of the master interface to increase its MTU as needed.
====================

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

11 files changed, 27 insertions, 0 deletions

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 23690c44e167..6ee2e24e0a6e 100644
--- a/include/net/dsa.h
+++ b/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 {
diff --git a/net/dsa/master.c b/net/dsa/master.c
index c90ee3227dea..42f525bc68e2 100644
--- a/net/dsa/master.c
+++ b/net/dsa/master.c
@@ -158,8 +158,24 @@ static void dsa_master_ethtool_teardown(struct net_device *dev)
 	cpu_dp->orig_ethtool_ops = NULL;
 }
 
+void dsa_master_set_mtu(struct net_device *dev, struct dsa_port *cpu_dp)
+{
+	unsigned int mtu = ETH_DATA_LEN + cpu_dp->tag_ops->overhead;
+	int err;
+
+	rtnl_lock();
+	if (mtu <= dev->max_mtu) {
+		err = dev_set_mtu(dev, mtu);
+		if (err)
+			netdev_dbg(dev, "Unable to set MTU to include for DSA overheads\n");
+	}
+	rtnl_unlock();
+}
+
 int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp)
 {
+	dsa_master_set_mtu(dev,  cpu_dp);
+
 	/* If we use a tagging format that doesn't have an ethertype
 	 * field, make sure that all packets from this point on get
 	 * sent to the tag format's receive function.
diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
index 2b06bb91318b..4aa1d368a5ae 100644
--- a/net/dsa/tag_brcm.c
+++ b/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
diff --git a/net/dsa/tag_dsa.c b/net/dsa/tag_dsa.c
index cd13cfc542ce..8b2f92e3f3a2 100644
--- a/net/dsa/tag_dsa.c
+++ b/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,
 };
diff --git a/net/dsa/tag_edsa.c b/net/dsa/tag_edsa.c
index 4083326b806e..f5b87ee5c94e 100644
--- a/net/dsa/tag_edsa.c
+++ b/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,
 };
diff --git a/net/dsa/tag_gswip.c b/net/dsa/tag_gswip.c
index 49e9b73f1be3..cb6f82ffe5eb 100644
--- a/net/dsa/tag_gswip.c
+++ b/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,
 };
diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 0f62effad88f..96411f70ab9f 100644
--- a/net/dsa/tag_ksz.c
+++ b/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,
 };
diff --git a/net/dsa/tag_lan9303.c b/net/dsa/tag_lan9303.c
index 548c00254c07..f48889e46ff7 100644
--- a/net/dsa/tag_lan9303.c
+++ b/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,
 };
diff --git a/net/dsa/tag_mtk.c b/net/dsa/tag_mtk.c
index 11535bc70743..f39f4dfeda34 100644
--- a/net/dsa/tag_mtk.c
+++ b/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,
 };
diff --git a/net/dsa/tag_qca.c b/net/dsa/tag_qca.c
index 613f4ee97771..ed4f6dc26365 100644
--- a/net/dsa/tag_qca.c
+++ b/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,
 };
diff --git a/net/dsa/tag_trailer.c b/net/dsa/tag_trailer.c
index 56197f0d9608..b40756ed6e57 100644
--- a/net/dsa/tag_trailer.c
+++ b/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,
 };