sunvnet: allow admin to set sunvnet MTU

This patch allows an admin to set the MTU on a sunvnet device to arbitrary
values between the minimum (68) and maximum (65535) IPv4 packet sizes.
Signed-off-by: David L Stevens <david.stevens@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/ldc.c

@@ -2159,7 +2159,7 @@ int ldc_map_single(struct ldc_channel *lp,
 	state.pte_idx = (base - iommu->page_table);
 	state.nc = 0;
 	fill_cookies(&state, (pa & PAGE_MASK), (pa & ~PAGE_MASK), len);
-	BUG_ON(state.nc != 1);
+	BUG_ON(state.nc > ncookies);
 
 	return state.nc;
 }

drivers/net/ethernet/sun/sunvnet.c

@@ -913,6 +913,9 @@ static int vnet_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (unlikely(!skb))
 		goto out_dropped;
 
+	if (skb->len > port->rmtu)
+		goto out_dropped;
+
 	spin_lock_irqsave(&port->vio.lock, flags);
 
 	dr = &port->vio.drings[VIO_DRIVER_TX_RING];
@@ -944,7 +947,7 @@ static int vnet_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	skb = NULL;
 
 	err = ldc_map_single(port->vio.lp, start, nlen,
-			     port->tx_bufs[txi].cookies, 2,
+			     port->tx_bufs[txi].cookies, VNET_MAXCOOKIES,
 			     (LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_RW));
 	if (err < 0) {
 		netdev_info(dev, "tx buffer map error %d\n", err);
@@ -1182,7 +1185,7 @@ static void vnet_set_rx_mode(struct net_device *dev)
 
 static int vnet_change_mtu(struct net_device *dev, int new_mtu)
 {
-	if (new_mtu != ETH_DATA_LEN)
+	if (new_mtu < 68 || new_mtu > 65535)
 		return -EINVAL;
 
 	dev->mtu = new_mtu;

drivers/net/ethernet/sun/sunvnet.h

@@ -16,7 +16,7 @@
  */
 #define	VNET_CLEAN_TIMEOUT		((HZ/100)+1)
 
-#define VNET_MAXPACKET			1518ULL /* ETH_FRAMELEN + VLAN_HDR */
+#define VNET_MAXPACKET			(65535ULL + ETH_HLEN + VLAN_HLEN)
 #define VNET_TX_RING_SIZE		512
 #define VNET_TX_WAKEUP_THRESH(dr)	((dr)->pending / 4)
 
@@ -26,10 +26,12 @@
  */
 #define VNET_PACKET_SKIP		6
 
+#define VNET_MAXCOOKIES			(VNET_MAXPACKET/PAGE_SIZE + 1)
+
 struct vnet_tx_entry {
 	struct sk_buff		*skb;
 	unsigned int		ncookies;
-	struct ldc_trans_cookie	cookies[2];
+	struct ldc_trans_cookie	cookies[VNET_MAXCOOKIES];
 };
 
 struct vnet;