Commit c95b819a authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ec2a5652

net/ipv4/ip_gre.c

+8 −7
Original line number Diff line number Diff line
@@ -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;

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