bonding: remap muticast addresses without using dev_close() and dev_open()

This patch fixes commit e36b9d16c6a6d0f59803b3ef04ff3c22c3844c10. The approach
there is to call dev_close()/dev_open() whenever the device type is changed in
order to remap the device IP multicast addresses to HW multicast addresses.
This approach suffers from 2 drawbacks:

*. It assumes tha the device is UP when calling dev_close(), or otherwise
dev_close() has no affect. It is worth to mention that initscripts (Redhat)
and sysconfig (Suse) doesn't act the same in this matter.
*. dev_close() has other side affects, like deleting entries from the routing
table, which might be unnecessary.

The fix here is to directly remap the IP multicast addresses to HW multicast
addresses for a bonding device that changes its type, and nothing else.

Reported-by: Jason Gunthorpe <[e-mail]>
Signed-off-by: Moni Shoua <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/bonding/bond_main.c

···
 			write_unlock_bh(&bond->curr_slave_lock);
 			read_unlock(&bond->lock);
 
-			netdev_bonding_change(bond->dev);
+			netdev_bonding_change(bond->dev, NETDEV_BONDING_FAILOVER);
 
 			read_lock(&bond->lock);
 			write_lock_bh(&bond->curr_slave_lock);
···
 	 */
 	if (bond->slave_cnt == 0) {
 		if (bond_dev->type != slave_dev->type) {
-			dev_close(bond_dev);
 			pr_debug("%s: change device type from %d to %d\n",
 				bond_dev->name, bond_dev->type, slave_dev->type);
+
+			netdev_bonding_change(bond_dev, NETDEV_BONDING_OLDTYPE);
+
 			if (slave_dev->type != ARPHRD_ETHER)
 				bond_setup_by_slave(bond_dev, slave_dev);
 			else
 				ether_setup(bond_dev);
-			dev_open(bond_dev);
+
+			netdev_bonding_change(bond_dev, NETDEV_BONDING_NEWTYPE);
 		}
 	} else if (bond_dev->type != slave_dev->type) {
 		pr_err(DRV_NAME ": %s ether type (%d) is different "

include/linux/igmp.h

···
 extern void ip_mc_destroy_dev(struct in_device *);
 extern void ip_mc_up(struct in_device *);
 extern void ip_mc_down(struct in_device *);
+extern void ip_mc_unmap(struct in_device *);
+extern void ip_mc_remap(struct in_device *);
 extern void ip_mc_dec_group(struct in_device *in_dev, __be32 addr);
 extern void ip_mc_inc_group(struct in_device *in_dev, __be32 addr);
 extern void ip_mc_rejoin_group(struct ip_mc_list *im);

include/linux/netdevice.h

···
 extern int		dev_set_promiscuity(struct net_device *dev, int inc);
 extern int		dev_set_allmulti(struct net_device *dev, int inc);
 extern void		netdev_state_change(struct net_device *dev);
-extern void		netdev_bonding_change(struct net_device *dev);
+extern void		netdev_bonding_change(struct net_device *dev,
+					      unsigned long event);
 extern void		netdev_features_change(struct net_device *dev);
 /* Load a device via the kmod */
 extern void		dev_load(struct net *net, const char *name);

include/linux/notifier.h

···
 #define NETDEV_FEAT_CHANGE	0x000B
 #define NETDEV_BONDING_FAILOVER 0x000C
 #define NETDEV_PRE_UP		0x000D
+#define NETDEV_BONDING_OLDTYPE  0x000E
+#define NETDEV_BONDING_NEWTYPE  0x000F
 
 #define SYS_DOWN	0x0001	/* Notify of system down */
 #define SYS_RESTART	SYS_DOWN

include/net/addrconf.h

···
 extern int ipv6_dev_mc_dec(struct net_device *dev, const struct in6_addr *addr);
 extern void ipv6_mc_up(struct inet6_dev *idev);
 extern void ipv6_mc_down(struct inet6_dev *idev);
+extern void ipv6_mc_unmap(struct inet6_dev *idev);
+extern void ipv6_mc_remap(struct inet6_dev *idev);
 extern void ipv6_mc_init_dev(struct inet6_dev *idev);
 extern void ipv6_mc_destroy_dev(struct inet6_dev *idev);
 extern void addrconf_dad_failure(struct inet6_ifaddr *ifp);

net/core/dev.c

···
 }
 EXPORT_SYMBOL(netdev_state_change);
 
-void netdev_bonding_change(struct net_device *dev)
+void netdev_bonding_change(struct net_device *dev, unsigned long event)
 {
-	call_netdevice_notifiers(NETDEV_BONDING_FAILOVER, dev);
+	call_netdevice_notifiers(event, dev);
 }
 EXPORT_SYMBOL(netdev_bonding_change);
 

net/ipv4/devinet.c

···
 	case NETDEV_DOWN:
 		ip_mc_down(in_dev);
 		break;
+	case NETDEV_BONDING_OLDTYPE:
+		ip_mc_unmap(in_dev);
+		break;
+	case NETDEV_BONDING_NEWTYPE:
+		ip_mc_remap(in_dev);
+		break;
 	case NETDEV_CHANGEMTU:
 		if (inetdev_valid_mtu(dev->mtu))
 			break;

net/ipv4/igmp.c

···
 	}
 }
 
+/* Device changing type */
+
+void ip_mc_unmap(struct in_device *in_dev)
+{
+	struct ip_mc_list *i;
+
+	ASSERT_RTNL();
+
+	for (i = in_dev->mc_list; i; i = i->next)
+		igmp_group_dropped(i);
+}
+
+void ip_mc_remap(struct in_device *in_dev)
+{
+	struct ip_mc_list *i;
+
+	ASSERT_RTNL();
+
+	for (i = in_dev->mc_list; i; i = i->next)
+		igmp_group_added(i);
+}
+
 /* Device going down */
 
 void ip_mc_down(struct in_device *in_dev)

net/ipv6/addrconf.c

···
 static void addrconf_join_anycast(struct inet6_ifaddr *ifp);
 static void addrconf_leave_anycast(struct inet6_ifaddr *ifp);
 
+static void addrconf_bonding_change(struct net_device *dev,
+				    unsigned long event);
 static int addrconf_ifdown(struct net_device *dev, int how);
 
 static void addrconf_dad_start(struct inet6_ifaddr *ifp, u32 flags);
···
 				return notifier_from_errno(err);
 		}
 		break;
+	case NETDEV_BONDING_OLDTYPE:
+	case NETDEV_BONDING_NEWTYPE:
+		addrconf_bonding_change(dev, event);
+		break;
 	}
 
 	return NOTIFY_OK;
···
 	.notifier_call = addrconf_notify,
 	.priority = 0
 };
+
+static void addrconf_bonding_change(struct net_device *dev, unsigned long event)
+{
+	struct inet6_dev *idev;
+	ASSERT_RTNL();
+
+	idev = __in6_dev_get(dev);
+
+	if (event == NETDEV_BONDING_NEWTYPE)
+		ipv6_mc_remap(idev);
+	else if (event == NETDEV_BONDING_OLDTYPE)
+		ipv6_mc_unmap(idev);
+}
 
 static int addrconf_ifdown(struct net_device *dev, int how)
 {

net/ipv6/mcast.c

···
 	ma_put(ma);
 }
 
+/* Device changing type */
+
+void ipv6_mc_unmap(struct inet6_dev *idev)
+{
+	struct ifmcaddr6 *i;
+
+	/* Install multicast list, except for all-nodes (already installed) */
+
+	read_lock_bh(&idev->lock);
+	for (i = idev->mc_list; i; i = i->next)
+		igmp6_group_dropped(i);
+	read_unlock_bh(&idev->lock);
+}
+
+void ipv6_mc_remap(struct inet6_dev *idev)
+{
+	ipv6_mc_up(idev);
+}
+
 /* Device going down */
 
 void ipv6_mc_down(struct inet6_dev *idev)