net/bonding: Handlle wrong assumptions that slave is always an Ethernet device

bonding sometimes uses Ethernet constants (such as MTU and address length) which
are not good when it enslaves non Ethernet devices (such as InfiniBand).

Signed-off-by: Moni Shoua <monis at voltaire.com>
Acked-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 3eebfe2..7be2336 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1225,7 +1225,8 @@
 	struct slave *slave;
 	struct net_device *bond_dev = bond->dev;
 	unsigned long features = bond_dev->features;
-	unsigned short max_hard_header_len = ETH_HLEN;
+	unsigned short max_hard_header_len = max((u16)ETH_HLEN,
+						bond_dev->hard_header_len);
 	int i;
 
 	features &= ~(NETIF_F_ALL_CSUM | BOND_VLAN_FEATURES);
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index ca4e429..583c568 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -260,6 +260,7 @@
 	char command[IFNAMSIZ + 1] = { 0, };
 	char *ifname;
 	int i, res, found, ret = count;
+	u32 original_mtu;
 	struct slave *slave;
 	struct net_device *dev = NULL;
 	struct bonding *bond = to_bond(d);
@@ -325,6 +326,7 @@
 		}
 
 		/* Set the slave's MTU to match the bond */
+		original_mtu = dev->mtu;
 		if (dev->mtu != bond->dev->mtu) {
 			if (dev->change_mtu) {
 				res = dev->change_mtu(dev,
@@ -339,6 +341,9 @@
 		}
 		rtnl_lock();
 		res = bond_enslave(bond->dev, dev);
+		bond_for_each_slave(bond, slave, i)
+			if (strnicmp(slave->dev->name, ifname, IFNAMSIZ) == 0)
+				slave->original_mtu = original_mtu;
 		rtnl_unlock();
 		if (res) {
 			ret = res;
@@ -351,6 +356,7 @@
 		bond_for_each_slave(bond, slave, i)
 			if (strnicmp(slave->dev->name, ifname, IFNAMSIZ) == 0) {
 				dev = slave->dev;
+				original_mtu = slave->original_mtu;
 				break;
 			}
 		if (dev) {
@@ -365,9 +371,9 @@
 			}
 			/* set the slave MTU to the default */
 			if (dev->change_mtu) {
-				dev->change_mtu(dev, 1500);
+				dev->change_mtu(dev, original_mtu);
 			} else {
-				dev->mtu = 1500;
+				dev->mtu = original_mtu;
 			}
 		}
 		else {
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 5011ba9..ad9c632 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -156,6 +156,7 @@
 	s8     link;    /* one of BOND_LINK_XXXX */
 	s8     state;   /* one of BOND_STATE_XXXX */
 	u32    original_flags;
+	u32    original_mtu;
 	u32    link_failure_count;
 	u16    speed;
 	u8     duplex;