[TAP]: Configurable interface MTU.

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

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d279151f065d1a94183c819ee7146aec9fa9c586..d8b8e68ef70b98aaefeffeeee6aa6d3d78e25b6b 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -172,6 +172,18 @@ tun_net_mclist(struct net_device *dev)
        }
 }
 
+#define MIN_MTU 68
+#define MAX_MTU 65535
+
+static int
+tun_net_change_mtu(struct net_device *dev, int new_mtu)
+{
+       if (new_mtu < MIN_MTU || new_mtu + dev->hard_header_len > MAX_MTU)
+               return -EINVAL;
+       dev->mtu = new_mtu;
+       return 0;
+}
+
 /* Initialize net device. */
 static void tun_net_init(struct net_device *dev)
 {
@@ -183,6 +195,7 @@ static void tun_net_init(struct net_device *dev)
                dev->hard_header_len = 0;
                dev->addr_len = 0;
                dev->mtu = 1500;
+               dev->change_mtu = tun_net_change_mtu;
 
                /* Zero header length */
                dev->type = ARPHRD_NONE;
@@ -195,6 +208,7 @@ static void tun_net_init(struct net_device *dev)
                dev->set_multicast_list = tun_net_mclist;
 
                ether_setup(dev);
+               dev->change_mtu = tun_net_change_mtu;
 
                /* random address already created for us by tun_set_iff, use it */
                memcpy(dev->dev_addr, tun->dev_addr, min(sizeof(tun->dev_addr), sizeof(dev->dev_addr)) );