ipvlan: fix IFLA_MTU ignored on NEWLINK

[ Upstream commit 30877961b1cdd6fdca783c2e8c4f0f47e95dc58c ]

Commit 296d48568042 ("ipvlan: inherit MTU from master device") adjusted
the mtu from the master device when creating a ipvlan device, but it
would also override the mtu value set in rtnl_create_link. It causes
IFLA_MTU param not to take effect.

So this patch is to not adjust the mtu if IFLA_MTU param is set when
creating a ipvlan device.

Fixes: 296d48568042 ("ipvlan: inherit MTU from master device")
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index c74893c..e7f7a1a 100644 (file)
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -546,7 +546,8 @@ int ipvlan_link_new(struct net *src_net, struct net_device *dev,
        ipvlan->dev = dev;
        ipvlan->port = port;
        ipvlan->sfeatures = IPVLAN_FEATURES;
-       ipvlan_adjust_mtu(ipvlan, phy_dev);
+       if (!tb[IFLA_MTU])
+               ipvlan_adjust_mtu(ipvlan, phy_dev);
        INIT_LIST_HEAD(&ipvlan->addrs);
 
        /* If the port-id base is at the MAX value, then wrap it around and