path: root/net/8021q/vlan_dev.c
diff options
authorPaolo Abeni <pabeni@redhat.com>2016-07-14 18:00:10 +0200
committerDavid S. Miller <davem@davemloft.net>2016-07-16 20:15:02 -0700
commit18d3df3eab23796d7f852f9c6bb60962b8372ced (patch)
tree4871d69274a682be6379696208efafc622d3234d /net/8021q/vlan_dev.c
parentnet: bgmac: Fix infinite loop in bgmac_dma_tx_add() (diff)
vlan: use a valid default mtu value for vlan over macsec
macsec can't cope with mtu frames which need vlan tag insertion, and vlan device set the default mtu equal to the underlying dev's one. By default vlan over macsec devices use invalid mtu, dropping all the large packets. This patch adds a netif helper to check if an upper vlan device needs mtu reduction. The helper is used during vlan devices initialization to set a valid default and during mtu updating to forbid invalid, too bit, mtu values. The helper currently only check if the lower dev is a macsec device, if we get more users, we need to update only the helper (possibly reserving an additional IFF bit). Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/8021q/vlan_dev.c')
1 files changed, 6 insertions, 4 deletions
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 86ae75b77390..516b0e73263c 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -146,10 +146,12 @@ static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb,
static int vlan_dev_change_mtu(struct net_device *dev, int new_mtu)
- /* TODO: gotta make sure the underlying layer can handle it,
- * maybe an IFF_VLAN_CAPABLE flag for devices?
- */
- if (vlan_dev_priv(dev)->real_dev->mtu < new_mtu)
+ struct net_device *real_dev = vlan_dev_priv(dev)->real_dev;
+ unsigned int max_mtu = real_dev->mtu;
+ if (netif_reduces_vlan_mtu(real_dev))
+ max_mtu -= VLAN_HLEN;
+ if (max_mtu < new_mtu)
return -ERANGE;
dev->mtu = new_mtu;