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geneve: Refine MTU limit

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Calculate the maximum MTU taking into account the size of headers
involved in GENEVE encapsulation, as for other tunnel types.

Changes in v3:
- Correct comment style
Changes in v2:
- Conform more closely to ip_tunnel_change_mtu
- Exclude GENEVE options from max MTU calculation

Signed-off-by: David Wragg <david@weave.works>
Acked-by: Jesse Gross <jesse@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Wragg 2016-02-18 17:43:29 +00:00 committed by David S. Miller
parent 7716682cc5
commit aeee0e66c6
1 changed files with 22 additions and 5 deletions
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27
drivers/net/geneve.c
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@ -1039,17 +1039,34 @@ static netdev_tx_t geneve_xmit(struct sk_buff *skb, struct net_device *dev)
return geneve_xmit_skb(skb, dev, info);
}
static int geneve_change_mtu(struct net_device *dev, int new_mtu)
static int __geneve_change_mtu(struct net_device *dev, int new_mtu, bool strict)
{
/* GENEVE overhead is not fixed, so we can't enforce a more
* precise max MTU.
/* The max_mtu calculation does not take account of GENEVE
* options, to avoid excluding potentially valid
* configurations.
*/
if (new_mtu < 68 || new_mtu > IP_MAX_MTU)
int max_mtu = IP_MAX_MTU - GENEVE_BASE_HLEN - sizeof(struct iphdr)
- dev->hard_header_len;
if (new_mtu < 68)
return -EINVAL;
if (new_mtu > max_mtu) {
if (strict)
return -EINVAL;
new_mtu = max_mtu;
}
dev->mtu = new_mtu;
return 0;
}
static int geneve_change_mtu(struct net_device *dev, int new_mtu)
{
return __geneve_change_mtu(dev, new_mtu, true);
}
static int geneve_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
{
struct ip_tunnel_info *info = skb_tunnel_info(skb);
@ -1459,7 +1476,7 @@ struct net_device *geneve_dev_create_fb(struct net *net, const char *name,
/* openvswitch users expect packet sizes to be unrestricted,
* so set the largest MTU we can.
*/
err = geneve_change_mtu(dev, IP_MAX_MTU);
err = __geneve_change_mtu(dev, IP_MAX_MTU, false);
if (err)
goto err;