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gre: Use needed_headroom 

Now that we have dev->needed_headroom, we can use it instead of
having a bogus dev->hard_header_len.  This also allows us to
include dev->hard_header_len in the MTU computation so that when
we do have a meaningful hard_harder_len in future it is included
automatically in figuring out the MTU.

Incidentally, this fixes a bug where we ignored the needed_headroom
field of the underlying device in calculating our own hard_header_len.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2008-10-09 11:58:54 -07:00 committed by David S. Miller
parent ec2a5652ea
commit c95b819ad7
1 changed files with 8 additions and 7 deletions
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15
net/ipv4/ip_gre.c
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@ -637,7 +637,7 @@ static int ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
df = tiph->frag_off;
if (df)
mtu = dst_mtu(&rt->u.dst) - tunnel->hlen;
mtu = dst_mtu(&rt->u.dst) - dev->hard_header_len - tunnel->hlen;
else
mtu = skb->dst ? dst_mtu(skb->dst) : dev->mtu;
@ -785,7 +785,7 @@ static void ipgre_tunnel_bind_dev(struct net_device *dev)
tunnel = netdev_priv(dev);
iph = &tunnel->parms.iph;
/* Guess output device to choose reasonable mtu and hard_header_len */
/* Guess output device to choose reasonable mtu and needed_headroom */
if (iph->daddr) {
struct flowi fl = { .oif = tunnel->parms.link,
@ -806,7 +806,7 @@ static void ipgre_tunnel_bind_dev(struct net_device *dev)
tdev = __dev_get_by_index(dev_net(dev), tunnel->parms.link);
if (tdev) {
hlen = tdev->hard_header_len;
hlen = tdev->hard_header_len + tdev->needed_headroom;
mtu = tdev->mtu;
}
dev->iflink = tunnel->parms.link;
@ -820,8 +820,8 @@ static void ipgre_tunnel_bind_dev(struct net_device *dev)
if (tunnel->parms.o_flags&GRE_SEQ)
addend += 4;
}
dev->hard_header_len = hlen + addend;
dev->mtu = mtu - addend;
dev->needed_headroom = addend + hlen;
dev->mtu = mtu - dev->hard_header_len - addend;
tunnel->hlen = addend;
}
@ -959,7 +959,8 @@ done:
static int ipgre_tunnel_change_mtu(struct net_device *dev, int new_mtu)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
if (new_mtu < 68 || new_mtu > 0xFFF8 - tunnel->hlen)
if (new_mtu < 68 ||
new_mtu > 0xFFF8 - dev->hard_header_len - tunnel->hlen)
return -EINVAL;
dev->mtu = new_mtu;
return 0;
@ -1085,7 +1086,7 @@ static void ipgre_tunnel_setup(struct net_device *dev)
dev->change_mtu = ipgre_tunnel_change_mtu;
dev->type = ARPHRD_IPGRE;
dev->hard_header_len = LL_MAX_HEADER + sizeof(struct iphdr) + 4;
dev->needed_headroom = LL_MAX_HEADER + sizeof(struct iphdr) + 4;
dev->mtu = ETH_DATA_LEN - sizeof(struct iphdr) - 4;
dev->flags = IFF_NOARP;
dev->iflink = 0;