While GENEVE allows variable length options, the maximum length of the
options is 63 * 4 bytes. So we can reasonably set an MTU limit other
than IP_MAX_MTU, as the other tunnel devices do.
Signed-off-by: David Wragg <david@weave.works>
---
drivers/net/geneve.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 028e387..f57f9bc 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -37,6 +37,9 @@ MODULE_PARM_DESC(log_ecn_error, "Log packets received with
corrupted ECN");
#define GENEVE_VER 0
#define GENEVE_BASE_HLEN (sizeof(struct udphdr) + sizeof(struct genevehdr))
+#define GENEVE_MAX_OPTIONS_LEN (63 * 4)
+#define GENEVE_MAX_MTU (IP_MAX_MTU - sizeof(struct iphdr) - GENEVE_BASE_HLEN \
+ - GENEVE_MAX_OPTIONS_LEN)
/* per-network namespace private data for this module */
struct geneve_net {
@@ -1041,11 +1044,9 @@ static netdev_tx_t geneve_xmit(struct sk_buff *skb,
struct net_device *dev)
static int geneve_change_mtu(struct net_device *dev, int new_mtu)
{
- /* GENEVE overhead is not fixed, so we can't enforce a more
- * precise max MTU.
- */
- if (new_mtu < 68 || new_mtu > IP_MAX_MTU)
+ if (new_mtu < 68 || new_mtu > GENEVE_MAX_MTU)
return -EINVAL;
+
dev->mtu = new_mtu;
return 0;
}
@@ -1459,7 +1460,7 @@ 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, GENEVE_MAX_MTU);
if (err)
goto err;
--
2.5.0
_______________________________________________
dev mailing list
dev@openvswitch.org
http://openvswitch.org/mailman/listinfo/dev
