bonding: gratuitous ARP

Add support for generating gratuitous ARPs in bonding
active-backup mode when failovers occur.  Includes support for VLAN
tagging the ARPs as needed.

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>

1 files changed, 251 insertions, 32 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 269a5e4..545f6fe 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -475,7 +475,10 @@
  *        Solution is to move call to dev_remove_pack outside of the
  *        spinlock.
  *        Set version to 2.6.1.
- *
+ * 2005/06/05 - Jay Vosburgh <fubar@us.ibm.com>
+ * 	- Support for generating gratuitous ARPs in active-backup mode.
+ * 	  Includes support for VLAN tagging all bonding-generated ARPs
+ * 	  as needed.  Set version to 2.6.2.
  */
 
 //#define BONDING_DEBUG 1
@@ -519,6 +522,7 @@
 #include <linux/ethtool.h>
 #include <linux/if_vlan.h>
 #include <linux/if_bonding.h>
+#include <net/route.h>
 #include "bonding.h"
 #include "bond_3ad.h"
 #include "bond_alb.h"
@@ -574,7 +578,6 @@ static struct proc_dir_entry *bond_proc_dir = NULL;
 
 static u32 arp_target[BOND_MAX_ARP_TARGETS] = { 0, } ;
 static int arp_ip_count	= 0;
-static u32 my_ip	= 0;
 static int bond_mode	= BOND_MODE_ROUNDROBIN;
 static int lacp_fast	= 0;
 static int app_abi_ver	= 0;
@@ -611,6 +614,7 @@ static struct bond_parm_tbl bond_mode_tbl[] = {
 /*-------------------------- Forward declarations ---------------------------*/
 
 static inline void bond_set_mode_ops(struct net_device *bond_dev, int mode);
+static void bond_send_gratuitous_arp(struct bonding *bond);
 
 /*---------------------------- General routines -----------------------------*/
 
@@ -659,6 +663,7 @@ static int bond_add_vlan(struct bonding *bond, unsigned short vlan_id)
 
 	INIT_LIST_HEAD(&vlan->vlan_list);
 	vlan->vlan_id = vlan_id;
+	vlan->vlan_ip = 0;
 
 	write_lock_bh(&bond->lock);
 
@@ -1468,16 +1473,6 @@ static void bond_change_active_slave(struct bonding *bond, struct slave *new_act
 		}
 	}
 
-	if (bond->params.mode == BOND_MODE_ACTIVEBACKUP) {
-		if (old_active) {
-			bond_set_slave_inactive_flags(old_active);
-		}
-
-		if (new_active) {
-			bond_set_slave_active_flags(new_active);
-		}
-	}
-
 	if (USES_PRIMARY(bond->params.mode)) {
 		bond_mc_swap(bond, new_active, old_active);
 	}
@@ -1488,6 +1483,17 @@ static void bond_change_active_slave(struct bonding *bond, struct slave *new_act
 	} else {
 		bond->curr_active_slave = new_active;
 	}
+
+	if (bond->params.mode == BOND_MODE_ACTIVEBACKUP) {
+		if (old_active) {
+			bond_set_slave_inactive_flags(old_active);
+		}
+
+		if (new_active) {
+			bond_set_slave_active_flags(new_active);
+		}
+		bond_send_gratuitous_arp(bond);
+	}
 }
 
 /**
@@ -2694,15 +2700,180 @@ out:
 	read_unlock(&bond->lock);
 }
 
+
+static u32 bond_glean_dev_ip(struct net_device *dev)
+{
+	struct in_device *idev;
+	struct in_ifaddr *ifa;
+	u32 addr = 0;
+
+	if (!dev)
+		return 0;
+
+	rcu_read_lock();
+	idev = __in_dev_get(dev);
+	if (!idev)
+		goto out;
+
+	ifa = idev->ifa_list;
+	if (!ifa)
+		goto out;
+
+	addr = ifa->ifa_local;
+out:
+	rcu_read_unlock();
+	return addr;
+}
+
+static int bond_has_ip(struct bonding *bond)
+{
+	struct vlan_entry *vlan, *vlan_next;
+
+	if (bond->master_ip)
+		return 1;
+
+	if (list_empty(&bond->vlan_list))
+		return 0;
+
+	list_for_each_entry_safe(vlan, vlan_next, &bond->vlan_list,
+				 vlan_list) {
+		if (vlan->vlan_ip)
+			return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * We go to the (large) trouble of VLAN tagging ARP frames because
+ * switches in VLAN mode (especially if ports are configured as
+ * "native" to a VLAN) might not pass non-tagged frames.
+ */
+static void bond_arp_send(struct net_device *slave_dev, int arp_op, u32 dest_ip, u32 src_ip, unsigned short vlan_id)
+{
+	struct sk_buff *skb;
+
+	dprintk("arp %d on slave %s: dst %x src %x vid %d\n", arp_op,
+	       slave_dev->name, dest_ip, src_ip, vlan_id);
+	       
+	skb = arp_create(arp_op, ETH_P_ARP, dest_ip, slave_dev, src_ip,
+			 NULL, slave_dev->dev_addr, NULL);
+
+	if (!skb) {
+		printk(KERN_ERR DRV_NAME ": ARP packet allocation failed\n");
+		return;
+	}
+	if (vlan_id) {
+		skb = vlan_put_tag(skb, vlan_id);
+		if (!skb) {
+			printk(KERN_ERR DRV_NAME ": failed to insert VLAN tag\n");
+			return;
+		}
+	}
+	arp_xmit(skb);
+}
+
+
 static void bond_arp_send_all(struct bonding *bond, struct slave *slave)
 {
-	int i;
+	int i, vlan_id, rv;
 	u32 *targets = bond->params.arp_targets;
+	struct vlan_entry *vlan, *vlan_next;
+	struct net_device *vlan_dev;
+	struct flowi fl;
+	struct rtable *rt;
 
 	for (i = 0; (i < BOND_MAX_ARP_TARGETS) && targets[i]; i++) {
-		arp_send(ARPOP_REQUEST, ETH_P_ARP, targets[i], slave->dev,
-			 my_ip, NULL, slave->dev->dev_addr,
-			 NULL);
+		dprintk("basa: target %x\n", targets[i]);
+		if (list_empty(&bond->vlan_list)) {
+			dprintk("basa: empty vlan: arp_send\n");
+			bond_arp_send(slave->dev, ARPOP_REQUEST, targets[i],
+				      bond->master_ip, 0);
+			continue;
+		}
+
+		/*
+		 * If VLANs are configured, we do a route lookup to
+		 * determine which VLAN interface would be used, so we
+		 * can tag the ARP with the proper VLAN tag.
+		 */
+		memset(&fl, 0, sizeof(fl));
+		fl.fl4_dst = targets[i];
+		fl.fl4_tos = RTO_ONLINK;
+
+		rv = ip_route_output_key(&rt, &fl);
+		if (rv) {
+			if (net_ratelimit()) {
+				printk(KERN_WARNING DRV_NAME
+			     ": %s: no route to arp_ip_target %u.%u.%u.%u\n",
+				       bond->dev->name, NIPQUAD(fl.fl4_dst));
+			}
+			continue;
+		}
+
+		/*
+		 * This target is not on a VLAN
+		 */
+		if (rt->u.dst.dev == bond->dev) {
+			dprintk("basa: rtdev == bond->dev: arp_send\n");
+			bond_arp_send(slave->dev, ARPOP_REQUEST, targets[i],
+				      bond->master_ip, 0);
+			continue;
+		}
+
+		vlan_id = 0;
+		list_for_each_entry_safe(vlan, vlan_next, &bond->vlan_list,
+					 vlan_list) {
+			vlan_dev = bond->vlgrp->vlan_devices[vlan->vlan_id];
+			if (vlan_dev == rt->u.dst.dev) {
+				vlan_id = vlan->vlan_id;
+				dprintk("basa: vlan match on %s %d\n",
+				       vlan_dev->name, vlan_id);
+				break;
+			}
+		}
+
+		if (vlan_id) {
+			bond_arp_send(slave->dev, ARPOP_REQUEST, targets[i],
+				      vlan->vlan_ip, vlan_id);
+			continue;
+		}
+
+		if (net_ratelimit()) {
+			printk(KERN_WARNING DRV_NAME
+	       ": %s: no path to arp_ip_target %u.%u.%u.%u via rt.dev %s\n",
+			       bond->dev->name, NIPQUAD(fl.fl4_dst),
+			       rt->u.dst.dev ? rt->u.dst.dev->name : "NULL");
+		}
+	}
+}
+
+/*
+ * Kick out a gratuitous ARP for an IP on the bonding master plus one
+ * for each VLAN above us.
+ */
+static void bond_send_gratuitous_arp(struct bonding *bond)
+{
+	struct slave *slave = bond->curr_active_slave;
+	struct vlan_entry *vlan;
+	struct net_device *vlan_dev;
+
+	dprintk("bond_send_grat_arp: bond %s slave %s\n", bond->dev->name,
+				slave ? slave->dev->name : "NULL");
+	if (!slave)
+		return;
+
+	if (bond->master_ip) {
+		bond_arp_send(slave->dev, ARPOP_REPLY, bond->master_ip,
+				  bond->master_ip, 0);
+	}
+
+	list_for_each_entry(vlan, &bond->vlan_list, vlan_list) {
+		vlan_dev = bond->vlgrp->vlan_devices[vlan->vlan_id];
+		if (vlan->vlan_ip) {
+			bond_arp_send(slave->dev, ARPOP_REPLY, vlan->vlan_ip,
+				      vlan->vlan_ip, vlan->vlan_id);
+		}
 	}
 }
 
@@ -2781,7 +2952,7 @@ static void bond_loadbalance_arp_mon(struct net_device *bond_dev)
 			 */
 			if (((jiffies - slave->dev->trans_start) >= (2*delta_in_ticks)) ||
 			    (((jiffies - slave->dev->last_rx) >= (2*delta_in_ticks)) &&
-			     my_ip)) {
+			     bond_has_ip(bond))) {
 
 				slave->link  = BOND_LINK_DOWN;
 				slave->state = BOND_STATE_BACKUP;
@@ -2920,7 +3091,7 @@ static void bond_activebackup_arp_mon(struct net_device *bond_dev)
 			if ((slave != bond->curr_active_slave) &&
 			    (!bond->current_arp_slave) &&
 			    (((jiffies - slave->dev->last_rx) >= 3*delta_in_ticks) &&
-			     my_ip)) {
+			     bond_has_ip(bond))) {
 				/* a backup slave has gone down; three times
 				 * the delta allows the current slave to be
 				 * taken out before the backup slave.
@@ -2966,8 +3137,8 @@ static void bond_activebackup_arp_mon(struct net_device *bond_dev)
 		 * if it is up and needs to take over as the curr_active_slave
 		 */
 		if ((((jiffies - slave->dev->trans_start) >= (2*delta_in_ticks)) ||
-		     (((jiffies - slave->dev->last_rx) >= (2*delta_in_ticks)) &&
-		      my_ip)) &&
+	    (((jiffies - slave->dev->last_rx) >= (2*delta_in_ticks)) &&
+	     bond_has_ip(bond))) &&
 		    ((jiffies - slave->jiffies) >= 2*delta_in_ticks)) {
 
 			slave->link  = BOND_LINK_DOWN;
@@ -3019,7 +3190,7 @@ static void bond_activebackup_arp_mon(struct net_device *bond_dev)
 		/* the current slave must tx an arp to ensure backup slaves
 		 * rx traffic
 		 */
-		if (slave && my_ip) {
+		if (slave && bond_has_ip(bond)) {
 			bond_arp_send_all(bond, slave);
 		}
 	}
@@ -3471,10 +3642,67 @@ static int bond_netdev_event(struct notifier_block *this, unsigned long event, v
 	return NOTIFY_DONE;
 }
 
+/*
+ * bond_inetaddr_event: handle inetaddr notifier chain events.
+ *
+ * We keep track of device IPs primarily to use as source addresses in
+ * ARP monitor probes (rather than spewing out broadcasts all the time).
+ *
+ * We track one IP for the main device (if it has one), plus one per VLAN.
+ */
+static int bond_inetaddr_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	struct in_ifaddr *ifa = ptr;
+	struct net_device *vlan_dev, *event_dev = ifa->ifa_dev->dev;
+	struct bonding *bond, *bond_next;
+	struct vlan_entry *vlan, *vlan_next;
+
+	list_for_each_entry_safe(bond, bond_next, &bond_dev_list, bond_list) {
+		if (bond->dev == event_dev) {
+			switch (event) {
+			case NETDEV_UP:
+				bond->master_ip = ifa->ifa_local;
+				return NOTIFY_OK;
+			case NETDEV_DOWN:
+				bond->master_ip = bond_glean_dev_ip(bond->dev);
+				return NOTIFY_OK;
+			default:
+				return NOTIFY_DONE;
+			}
+		}
+
+		if (list_empty(&bond->vlan_list))
+			continue;
+
+		list_for_each_entry_safe(vlan, vlan_next, &bond->vlan_list,
+					 vlan_list) {
+			vlan_dev = bond->vlgrp->vlan_devices[vlan->vlan_id];
+			if (vlan_dev == event_dev) {
+				switch (event) {
+				case NETDEV_UP:
+					vlan->vlan_ip = ifa->ifa_local;
+					return NOTIFY_OK;
+				case NETDEV_DOWN:
+					vlan->vlan_ip =
+						bond_glean_dev_ip(vlan_dev);
+					return NOTIFY_OK;
+				default:
+					return NOTIFY_DONE;
+				}
+			}
+		}
+	}
+	return NOTIFY_DONE;
+}
+
 static struct notifier_block bond_netdev_notifier = {
 	.notifier_call = bond_netdev_event,
 };
 
+static struct notifier_block bond_inetaddr_notifier = {
+	.notifier_call = bond_inetaddr_event,
+};
+
 /*-------------------------- Packet type handling ---------------------------*/
 
 /* register to receive lacpdus on a bond */
@@ -4060,17 +4288,6 @@ static int bond_xmit_activebackup(struct sk_buff *skb, struct net_device *bond_d
 	struct bonding *bond = bond_dev->priv;
 	int res = 1;
 
-	/* if we are sending arp packets, try to at least
-	   identify our own ip address */
-	if (bond->params.arp_interval && !my_ip &&
-		(skb->protocol == __constant_htons(ETH_P_ARP))) {
-		char *the_ip = (char *)skb->data +
-				sizeof(struct ethhdr) +
-				sizeof(struct arphdr) +
-				ETH_ALEN;
-		memcpy(&my_ip, the_ip, 4);
-	}
-
 	read_lock(&bond->lock);
 	read_lock(&bond->curr_slave_lock);
 
@@ -4669,6 +4886,7 @@ static int __init bonding_init(void)
 
 	rtnl_unlock();
 	register_netdevice_notifier(&bond_netdev_notifier);
+	register_inetaddr_notifier(&bond_inetaddr_notifier);
 
 	return 0;
 
@@ -4684,6 +4902,7 @@ out_err:
 static void __exit bonding_exit(void)
 {
 	unregister_netdevice_notifier(&bond_netdev_notifier);
+	unregister_inetaddr_notifier(&bond_inetaddr_notifier);
 
 	rtnl_lock();
 	bond_free_all();