vlan: support "loose binding" to the underlying network device

Currently the UP/DOWN state of VLANs is synchronized to the state of the
underlying device, meaning all VLANs are set down once the underlying
device is set down. This causes all routes to the VLAN devices to vanish.

Add a flag to specify a "loose binding" mode, in which only the operstate
is transfered, but the VLAN device state is independant.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 2 deletions

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 1483243edf14..225aa2fac0e3 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -431,6 +431,7 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
         struct vlan_group *grp;
         int i, flgs;
         struct net_device *vlandev;
+        struct vlan_dev_info *vlan;
         LIST_HEAD(list);
 
         if (is_vlan_dev(dev))
@@ -507,7 +508,9 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
                         if (!(flgs & IFF_UP))
                                 continue;
 
-                        dev_change_flags(vlandev, flgs & ~IFF_UP);
+                        vlan = vlan_dev_info(vlandev);
+                        if (!(vlan->flags & VLAN_FLAG_LOOSE_BINDING))
+                                dev_change_flags(vlandev, flgs & ~IFF_UP);
                         vlan_transfer_operstate(dev, vlandev);
                 }
                 break;
@@ -523,7 +526,9 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
                         if (flgs & IFF_UP)
                                 continue;
 
-                        dev_change_flags(vlandev, flgs | IFF_UP);
+                        vlan = vlan_dev_info(vlandev);
+                        if (!(vlan->flags & VLAN_FLAG_LOOSE_BINDING))
+                                dev_change_flags(vlandev, flgs | IFF_UP);
                         vlan_transfer_operstate(dev, vlandev);
                 }
                 break;