gre: Move MTU setting out of ipgre_tunnel_bind_dev

This patch moves the dev->mtu setting out of ipgre_tunnel_bind_dev.
This is in prepartion of using rtnl_link where we'll need to make
the MTU setting conditional on whether the user has supplied an
MTU.  This also requires the move of the ipgre_tunnel_bind_dev
call out of the dev->init function so that we can access the user
parameters later.

This patch also adds a check to prevent setting the MTU below
the minimum of 68.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index fd192d676955fde161200bc37c4bc07650292a00..80622dd6fb3f7cec0b01b95c4fb6f5dfd86a6079 100644 (file)
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -119,6 +119,7 @@
 
 static int ipgre_tunnel_init(struct net_device *dev);
 static void ipgre_tunnel_setup(struct net_device *dev);
+static int ipgre_tunnel_bind_dev(struct net_device *dev);
 
 /* Fallback tunnel: no source, no destination, no key, no options */
 
@@ -289,6 +290,8 @@ static struct ip_tunnel * ipgre_tunnel_locate(struct net *net,
        nt = netdev_priv(dev);
        nt->parms = *parms;
 
+       dev->mtu = ipgre_tunnel_bind_dev(dev);
+
        if (register_netdevice(dev) < 0)
                goto failed_free;
 
@@ -773,7 +776,7 @@ tx_error:
        return 0;
 }
 
-static void ipgre_tunnel_bind_dev(struct net_device *dev)
+static int ipgre_tunnel_bind_dev(struct net_device *dev)
 {
        struct net_device *tdev = NULL;
        struct ip_tunnel *tunnel;
@@ -821,9 +824,14 @@ static void ipgre_tunnel_bind_dev(struct net_device *dev)
                        addend += 4;
        }
        dev->needed_headroom = addend + hlen;
-       dev->mtu = mtu - dev->hard_header_len - addend;
+       mtu -= dev->hard_header_len - addend;
+
+       if (mtu < 68)
+               mtu = 68;
+
        tunnel->hlen = addend;
 
+       return mtu;
 }
 
 static int
@@ -917,7 +925,7 @@ ipgre_tunnel_ioctl (struct net_device *dev, struct ifreq *ifr, int cmd)
                                t->parms.iph.frag_off = p.iph.frag_off;
                                if (t->parms.link != p.link) {
                                        t->parms.link = p.link;
-                                       ipgre_tunnel_bind_dev(dev);
+                                       dev->mtu = ipgre_tunnel_bind_dev(dev);
                                        netdev_state_change(dev);
                                }
                        }
@@ -1108,8 +1116,6 @@ static int ipgre_tunnel_init(struct net_device *dev)
        memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
        memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 
-       ipgre_tunnel_bind_dev(dev);
-
        if (iph->daddr) {
 #ifdef CONFIG_NET_IPGRE_BROADCAST
                if (ipv4_is_multicast(iph->daddr)) {