netdev - [PATCH net] ip_gre: remove the incorrect mtu limit for ipgre tap

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Date:   Mon, 18 Dec 2017 14:24:35 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>
Cc:     davem@...emloft.net, Jarod Wilson <jarod@...hat.com>
Subject: [PATCH net] ip_gre: remove the incorrect mtu limit for ipgre tap

ipgre tap driver calls ether_setup(), after commit 61e84623ace3
("net: centralize net_device min/max MTU checking"), the range
of mtu is [min_mtu, max_mtu], which is [68, 1500] by default.

It causes the dev mtu of the ipgre tap device to not be greater
than 1500, this limit value is not correct for ipgre tap device.

Besides, it's .change_mtu already does the right check. So this
patch is just to set max_mtu as 0, and leave the check to it's
.change_mtu.

Fixes: 61e84623ace3 ("net: centralize net_device min/max MTU checking")
Reported-by: Jianlin Shi <jishi@...hat.com>
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/ipv4/ip_gre.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 9c17356..45ffd3d 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1310,6 +1310,7 @@ static const struct net_device_ops erspan_netdev_ops = {
 static void ipgre_tap_setup(struct net_device *dev)
 {
 	ether_setup(dev);
+	dev->max_mtu = 0;
 	dev->netdev_ops	= &gre_tap_netdev_ops;
 	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 	dev->priv_flags	|= IFF_LIVE_ADDR_CHANGE;
-- 
2.1.0