When create a new vxlan link, example:
  ip link add vtap mtu 1440 type vxlan vni 1 dev eth0

The argument "mtu" has no effect, because it is not set to conf->mtu. The
default value is used in vxlan_dev_configure function.

This problem was introduced by commit 0dfbdf4102b9 (vxlan: Factor out device
configuration).

Fixes: 0dfbdf4102b9 (vxlan: Factor out device configuration)

Signed-off-by:  Chen Haiquan <redacted>
---
 drivers/net/vxlan.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 8ff30c3..f999db2 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c

@@ -3086,6 +3086,9 @@ static int vxlan_newlink(struct net *src_net, struct net_device *dev,
        if (data[IFLA_VXLAN_REMCSUM_NOPARTIAL])
                conf.flags |= VXLAN_F_REMCSUM_NOPARTIAL;

+       if (tb[IFLA_MTU])
+               conf.mtu = nla_get_u32(tb[IFLA_MTU]);
+