net/bonding: Delay sending of gratuitous ARP to avoid failure

Delay sending a gratuitous_arp when LINK_STATE_LINKWATCH_PENDING bit
in dev->state field is on. This improves the chances for the arp packet to
be transmitted.

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>

drivers/net/bonding/bond_main.c

@@ -1103,7 +1103,13 @@ void bond_change_active_slave(struct bonding *bond, struct slave *new_active)
 		if (new_active && !bond->do_set_mac_addr)
 			memcpy(bond->dev->dev_addr,  new_active->dev->dev_addr,
 				new_active->dev->addr_len);
-
+		if (bond->curr_active_slave &&
+			test_bit(__LINK_STATE_LINKWATCH_PENDING,
+					&bond->curr_active_slave->dev->state)) {
+			dprintk("delaying gratuitous arp on %s\n",
+				bond->curr_active_slave->dev->name);
+			bond->send_grat_arp = 1;
+		} else
 			bond_send_gratuitous_arp(bond);
 	}
 }
@@ -2073,6 +2079,17 @@ void bond_mii_monitor(struct net_device *bond_dev)
 	 * program could monitor the link itself if needed.
 	 */
 
+	if (bond->send_grat_arp) {
+		if (bond->curr_active_slave && test_bit(__LINK_STATE_LINKWATCH_PENDING,
+				&bond->curr_active_slave->dev->state))
+			dprintk("Needs to send gratuitous arp but not yet\n");
+		else {
+			dprintk("sending delayed gratuitous arp on on %s\n",
+				bond->curr_active_slave->dev->name);
+			bond_send_gratuitous_arp(bond);
+			bond->send_grat_arp = 0;
+		}
+	}
 	read_lock(&bond->curr_slave_lock);
 	oldcurrent = bond->curr_active_slave;
 	read_unlock(&bond->curr_slave_lock);
@@ -4280,6 +4297,7 @@ static int bond_init(struct net_device *bond_dev, struct bond_params *params)
 	bond->current_arp_slave = NULL;
 	bond->primary_slave = NULL;
 	bond->dev = bond_dev;
+	bond->send_grat_arp = 0;
 	INIT_LIST_HEAD(&bond->vlan_list);
 
 	/* Initialize the device entry points */

drivers/net/bonding/bonding.h

@@ -187,6 +187,7 @@ struct bonding {
 	struct   timer_list arp_timer;
 	s8       kill_timers;
 	s8       do_set_mac_addr;
+	s8	 send_grat_arp;
 	struct   net_device_stats stats;
 #ifdef CONFIG_PROC_FS
 	struct   proc_dir_entry *proc_entry;