net/bonding: Destroy bonding master when last slave is gone

When bonding enslaves non Ethernet devices it takes pointers to functions
in the module that owns the slaves. In this case it becomes unsafe
to keep the bonding master registered after last slave was unenslaved
because we don't know if the pointers are still valid.  Destroying the bond when slave_cnt is zero
ensures that these functions be used anymore.

Signed-off-by: Moni Shoua <monis at voltaire.com>
Acked-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 19fd35175a77..0e198dd87c20 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1257,6 +1257,8 @@ static int bond_compute_features(struct bonding *bond)
 static void bond_setup_by_slave(struct net_device *bond_dev,
                                 struct net_device *slave_dev)
 {
+        struct bonding *bond = bond_dev->priv;
+
         bond_dev->neigh_setup           = slave_dev->neigh_setup;
 
         bond_dev->type              = slave_dev->type;
@@ -1265,6 +1267,7 @@ static void bond_setup_by_slave(struct net_device *bond_dev,
 
         memcpy(bond_dev->broadcast, slave_dev->broadcast,
                 slave_dev->addr_len);
+        bond->setup_by_slave = 1;
 }
 
 /* enslave device <slave> to bond device <master> */
@@ -1828,6 +1831,35 @@ int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
 }
 
 /*
+* Destroy a bonding device.
+* Must be under rtnl_lock when this function is called.
+*/
+void bond_destroy(struct bonding *bond)
+{
+        bond_deinit(bond->dev);
+        bond_destroy_sysfs_entry(bond);
+        unregister_netdevice(bond->dev);
+}
+
+/*
+* First release a slave and than destroy the bond if no more slaves iare left.
+* Must be under rtnl_lock when this function is called.
+*/
+int  bond_release_and_destroy(struct net_device *bond_dev, struct net_device *slave_dev)
+{
+        struct bonding *bond = bond_dev->priv;
+        int ret;
+
+        ret = bond_release(bond_dev, slave_dev);
+        if ((ret == 0) && (bond->slave_cnt == 0)) {
+                printk(KERN_INFO DRV_NAME ": %s: destroying bond %s.\n",
+                       bond_dev->name, bond_dev->name);
+                bond_destroy(bond);
+        }
+        return ret;
+}
+
+/*
  * This function releases all slaves.
  */
 static int bond_release_all(struct net_device *bond_dev)
@@ -3325,6 +3357,11 @@ static int bond_slave_netdev_event(unsigned long event, struct net_device *slave
                  * ... Or is it this?
                  */
                 break;
+        case NETDEV_GOING_DOWN:
+                dprintk("slave %s is going down\n", slave_dev->name);
+                if (bond->setup_by_slave)
+                        bond_release_and_destroy(bond_dev, slave_dev);
+                break;
         case NETDEV_CHANGEMTU:
                 /*
                  * TODO: Should slaves be allowed to
@@ -4298,6 +4335,7 @@ static int bond_init(struct net_device *bond_dev, struct bond_params *params)
         bond->primary_slave = NULL;
         bond->dev = bond_dev;
         bond->send_grat_arp = 0;
+        bond->setup_by_slave = 0;
         INIT_LIST_HEAD(&bond->vlan_list);
 
         /* Initialize the device entry points */