bonding: properly unset current_arp_slave on slave link up

When a slave comes up, we're unsetting the current_arp_slave without
removing active flags from it, which can lead to situations where we have
more than one slave with active flags in active-backup mode.

To avoid this situation we must remove the active flags from a slave before
removing it as a current_arp_slave.

Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -3010,7 +3010,11 @@ static void bond_ab_arp_commit(struct bonding *bond, int delta_in_ticks)
 					   trans_start + delta_in_ticks)) ||
 			    bond->curr_active_slave != slave) {
 				slave->link = BOND_LINK_UP;
-				bond->current_arp_slave = NULL;
+				if (bond->current_arp_slave) {
+					bond_set_slave_inactive_flags(
+						bond->current_arp_slave);
+					bond->current_arp_slave = NULL;
+				}
 
 				pr_info("%s: link status definitely up for interface %s.\n",
 					bond->dev->name, slave->dev->name);