bonding: make ad_port_selection_logic() use bond_for_each_slave()

Currently, ad_port_selection_logic() uses

for (aggregator = __get_first_agg(port); aggregator;
     aggregator = __get_next_agg(aggregator)) {

construct, however it's suboptimal, difficult to read and understand.

Change it to a standard bond_for_each_slave(), so that we won't need
__get_first/next_agg() and have it more readable.

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

drivers/net/bonding/bond_3ad.c

@@ -1239,12 +1239,17 @@ static void ad_port_selection_logic(struct port *port)
 {
 	struct aggregator *aggregator, *free_aggregator = NULL, *temp_aggregator;
 	struct port *last_port = NULL, *curr_port;
+	struct list_head *iter;
+	struct bonding *bond;
+	struct slave *slave;
 	int found = 0;
 
 	// if the port is already Selected, do nothing
 	if (port->sm_vars & AD_PORT_SELECTED)
 		return;
 
+	bond = __get_bond_by_port(port);
+
 	// if the port is connected to other aggregator, detach it
 	if (port->aggregator) {
 		// detach the port from its former aggregator
@@ -1285,8 +1290,8 @@ static void ad_port_selection_logic(struct port *port)
 		}
 	}
 	// search on all aggregators for a suitable aggregator for this port
-	for (aggregator = __get_first_agg(port); aggregator;
-	     aggregator = __get_next_agg(aggregator)) {
+	bond_for_each_slave(bond, slave, iter) {
+		aggregator = &(SLAVE_AD_INFO(slave).aggregator);
 
 		// keep a free aggregator for later use(if needed)
 		if (!aggregator->lag_ports) {