bonding: move bond-specific init after enslave happens

As Jiri noted, currently we first do all bonding-specific initialization
(specifically - bond_select_active_slave(bond)) before we actually attach
the slave (so that it becomes visible through bond_for_each_slave() and
friends). This might result in bond_select_active_slave() not seeing the
first/new slave and, thus, not actually selecting an active slave.

Fix this by moving all the bond-related init part after we've actually
completely initialized and linked (via bond_master_upper_dev_link()) the
new slave.

Also, remove the bond_(de/a)ttach_slave(), it's useless to have functions
to ++/-- one int.

After this we have all the initialization of the new slave *before*
linking, and all the stuff that needs to be done on bonding *after* it. It
has also a bonus effect - we can remove the locking on the new slave init
completely, and only use it for bond_select_active_slave().

Reported-by: Jiri Pirko <jiri@resnulli.us>
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Acked-by: Ding Tianhong@huawei.com
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -967,33 +967,6 @@ void bond_select_active_slave(struct bonding *bond)
 	}
 }
 
-/*--------------------------- slave list handling ---------------------------*/
-
-/*
- * This function attaches the slave to the end of list.
- *
- * bond->lock held for writing by caller.
- */
-static void bond_attach_slave(struct bonding *bond, struct slave *new_slave)
-{
-	bond->slave_cnt++;
-}
-
-/*
- * This function detaches the slave from the list.
- * WARNING: no check is made to verify if the slave effectively
- * belongs to <bond>.
- * Nothing is freed on return, structures are just unchained.
- * If any slave pointer in bond was pointing to <slave>,
- * it should be changed by the calling function.
- *
- * bond->lock held for writing by caller.
- */
-static void bond_detach_slave(struct bonding *bond, struct slave *slave)
-{
-	bond->slave_cnt--;
-}
-
 #ifdef CONFIG_NET_POLL_CONTROLLER
 static inline int slave_enable_netpoll(struct slave *slave)
 {
@@ -1471,22 +1444,13 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 		goto err_close;
 	}
 
-	write_lock_bh(&bond->lock);
-
 	prev_slave = bond_last_slave(bond);
-	bond_attach_slave(bond, new_slave);
 
 	new_slave->delay = 0;
 	new_slave->link_failure_count = 0;
 
-	write_unlock_bh(&bond->lock);
-
-	bond_compute_features(bond);
-
 	bond_update_speed_duplex(new_slave);
 
-	read_lock(&bond->lock);
-
 	new_slave->last_arp_rx = jiffies -
 		(msecs_to_jiffies(bond->params.arp_interval) + 1);
 	for (i = 0; i < BOND_MAX_ARP_TARGETS; i++)
@@ -1547,12 +1511,9 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 		}
 	}
 
-	write_lock_bh(&bond->curr_slave_lock);
-
 	switch (bond->params.mode) {
 	case BOND_MODE_ACTIVEBACKUP:
 		bond_set_slave_inactive_flags(new_slave);
-		bond_select_active_slave(bond);
 		break;
 	case BOND_MODE_8023AD:
 		/* in 802.3ad mode, the internal mechanism
@@ -1578,7 +1539,6 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	case BOND_MODE_ALB:
 		bond_set_active_slave(new_slave);
 		bond_set_slave_inactive_flags(new_slave);
-		bond_select_active_slave(bond);
 		break;
 	default:
 		pr_debug("This slave is always active in trunk mode\n");
@@ -1596,10 +1556,6 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 		break;
 	} /* switch(bond_mode) */
 
-	write_unlock_bh(&bond->curr_slave_lock);
-
-	bond_set_carrier(bond);
-
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	slave_dev->npinfo = bond->dev->npinfo;
 	if (slave_dev->npinfo) {
@@ -1614,8 +1570,6 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	}
 #endif
 
-	read_unlock(&bond->lock);
-
 	res = netdev_rx_handler_register(slave_dev, bond_handle_frame,
 					 new_slave);
 	if (res) {
@@ -1629,6 +1583,17 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 		goto err_unregister;
 	}
 
+	bond->slave_cnt++;
+	bond_compute_features(bond);
+	bond_set_carrier(bond);
+
+	if (USES_PRIMARY(bond->params.mode)) {
+		read_lock(&bond->lock);
+		write_lock_bh(&bond->curr_slave_lock);
+		bond_select_active_slave(bond);
+		write_unlock_bh(&bond->curr_slave_lock);
+		read_unlock(&bond->lock);
+	}
 
 	pr_info("%s: enslaving %s as a%s interface with a%s link.\n",
 		bond_dev->name, slave_dev->name,
@@ -1648,7 +1613,6 @@ err_detach:
 
 	vlan_vids_del_by_dev(slave_dev, bond_dev);
 	write_lock_bh(&bond->lock);
-	bond_detach_slave(bond, new_slave);
 	if (bond->primary_slave == new_slave)
 		bond->primary_slave = NULL;
 	if (bond->curr_active_slave == new_slave) {
@@ -1686,7 +1650,6 @@ err_free:
 	kfree(new_slave);
 
 err_undo_flags:
-	bond_compute_features(bond);
 	/* Enslave of first slave has failed and we need to fix master's mac */
 	if (!bond_has_slaves(bond) &&
 	    ether_addr_equal(bond_dev->dev_addr, slave_dev->dev_addr))
@@ -1740,6 +1703,9 @@ static int __bond_release_one(struct net_device *bond_dev,
 
 	write_unlock_bh(&bond->lock);
 
+	/* release the slave from its bond */
+	bond->slave_cnt--;
+
 	bond_upper_dev_unlink(bond_dev, slave_dev);
 	/* unregister rx_handler early so bond_handle_frame wouldn't be called
 	 * for this slave anymore.
@@ -1764,9 +1730,6 @@ static int __bond_release_one(struct net_device *bond_dev,
 
 	bond->current_arp_slave = NULL;
 
-	/* release the slave from its bond */
-	bond_detach_slave(bond, slave);
-
 	if (!all && !bond->params.fail_over_mac) {
 		if (ether_addr_equal(bond_dev->dev_addr, slave->perm_hwaddr) &&
 		    bond_has_slaves(bond))