Commit 701470ba authored by Sven Eckelmann's avatar Sven Eckelmann Committed by David S. Miller
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batman-adv: Revert "use core MTU range checking in misc drivers"

The maximum MTU is defined via the slave devices of an batman-adv
interface. Thus it is not possible to calculate the max_mtu during the
creation of the batman-adv device when no slave devices are attached. Doing
so would for example break non-fragmentation setups which then
(incorrectly) allow an MTU of 1500 even when underlying device cannot
transport 1500 bytes + batman-adv headers.

Checking the dynamically calculated max_mtu via the minimum of the slave
devices MTU during .ndo_change_mtu is also used by the bridge interface.

Cc: Jarod Wilson <>
Fixes: b3e3893e

 ("net: use core MTU range checking in misc drivers")
Signed-off-by: default avatarSven Eckelmann <>
Signed-off-by: default avatarDavid S. Miller <>
parent f806f772
......@@ -158,6 +158,17 @@ static int batadv_interface_set_mac_addr(struct net_device *dev, void *p)
return 0;
static int batadv_interface_change_mtu(struct net_device *dev, int new_mtu)
/* check ranges */
if ((new_mtu < 68) || (new_mtu > batadv_hardif_min_mtu(dev)))
return -EINVAL;
dev->mtu = new_mtu;
return 0;
* batadv_interface_set_rx_mode - set the rx mode of a device
* @dev: registered network device to modify
......@@ -909,6 +920,7 @@ static const struct net_device_ops batadv_netdev_ops = {
.ndo_vlan_rx_add_vid = batadv_interface_add_vid,
.ndo_vlan_rx_kill_vid = batadv_interface_kill_vid,
.ndo_set_mac_address = batadv_interface_set_mac_addr,
.ndo_change_mtu = batadv_interface_change_mtu,
.ndo_set_rx_mode = batadv_interface_set_rx_mode,
.ndo_start_xmit = batadv_interface_tx,
.ndo_validate_addr = eth_validate_addr,
......@@ -975,7 +987,6 @@ struct net_device *batadv_softif_create(struct net *net, const char *name)
dev_net_set(soft_iface, net);
soft_iface->rtnl_link_ops = &batadv_link_ops;
soft_iface->max_mtu = batadv_hardif_min_mtu(soft_iface);
ret = register_netdevice(soft_iface);
if (ret < 0) {
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