[PATCH net] bonding: Prevent IPv6 link local address on enslaved devices

[Karl Heiss <kheiss@gmail.com>]

Upstream commit 1f718f0f4f97 ("bonding: populate neighbour's private on
enslave") undoes the fix provided by commit c2edacf80e15 ("bonding / ipv6: no
addrconf for slaves separately from master") by effectively setting
the slave flag after the slave has been opened.  If the slave comes up quickly
enough, it will go through the IPv6 addrconf before the slave flag has been
set and will get a link local IPv6 address.

Set IFF_SLAVE before dev_open() and clear it after dev_close() to ensure that
addrconf knows to ignore on state change.

Fixes: 1f718f0f4f97 ("bonding: populate neighbour's private on enslave")

Signed-off-by: Karl Heiss <kheiss@gmail.com>
---
 drivers/net/bonding/bond_main.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 9e0f8a7..200358e 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1207,7 +1207,6 @@ static int bond_master_upper_dev_link(struct net_device *bond_dev,
 	err = netdev_master_upper_dev_link_private(slave_dev, bond_dev, slave);
 	if (err)
 		return err;
-	slave_dev->flags |= IFF_SLAVE;
 	rtmsg_ifinfo(RTM_NEWLINK, slave_dev, IFF_SLAVE, GFP_KERNEL);
 	return 0;
 }
@@ -1216,7 +1215,6 @@ static void bond_upper_dev_unlink(struct net_device *bond_dev,
 				  struct net_device *slave_dev)
 {
 	netdev_upper_dev_unlink(slave_dev, bond_dev);
-	slave_dev->flags &= ~IFF_SLAVE;
 	rtmsg_ifinfo(RTM_NEWLINK, slave_dev, IFF_SLAVE, GFP_KERNEL);
 }
 
@@ -1465,6 +1463,9 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 		}
 	}
 
+	/* set slave flag before open to prevent IPv6 addrconf */
+	slave_dev->flags |= IFF_SLAVE;
+
 	/* open the slave since the application closed it */
 	res = dev_open(slave_dev);
 	if (res) {
@@ -1725,6 +1726,7 @@ err_close:
 	dev_close(slave_dev);
 
 err_restore_mac:
+	slave_dev->flags &= ~IFF_SLAVE;
 	if (!bond->params.fail_over_mac ||
 	    BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
 		/* XXX TODO - fom follow mode needs to change master's
@@ -1906,6 +1908,8 @@ static int __bond_release_one(struct net_device *bond_dev,
 	/* close slave before restoring its mac address */
 	dev_close(slave_dev);
 
+	slave_dev->flags &= ~IFF_SLAVE;
+
 	if (bond->params.fail_over_mac != BOND_FOM_ACTIVE ||
 	    BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
 		/* restore original ("permanent") mac address */
-- 
1.7.1