[netdrvr bonding] fix long failover in 802.3ad mode

This patch fixes the bug reported by Jay on April 3rd regarding long
failover time when releasing the last slave in the active aggregator. The
fix, as suggested by Jay, is to follow the spec recommendation and send a
LACPDU to the partner saying this port is no longer aggregatable and
therefore trigger an immediate re-selection of a new aggregator instead of
waiting the entire expiration timeout.

drivers/net/bonding/bond_3ad.c

@@ -721,7 +721,7 @@ static void __attach_bond_to_agg(struct port *port)
 }
 
 /**
- * __detach_bond_to_agg
+ * __detach_bond_from_agg
  * @port: the port we're looking at
  *
  * Handle the detaching of the port's control parser/multiplexer from the
@@ -828,6 +828,55 @@ static struct aggregator *__get_active_agg(struct aggregator *aggregator)
 	return retval;
 }
 
+/**
+ * __update_lacpdu_from_port - update a port's lacpdu fields
+ * @port: the port we're looking at
+ *
+ */
+static inline void __update_lacpdu_from_port(struct port *port)
+{
+	struct lacpdu *lacpdu = &port->lacpdu;
+
+	/* update current actual Actor parameters */
+	/* lacpdu->subtype                   initialized
+	 * lacpdu->version_number            initialized
+	 * lacpdu->tlv_type_actor_info       initialized
+	 * lacpdu->actor_information_length  initialized
+	 */
+
+	lacpdu->actor_system_priority = port->actor_system_priority;
+	lacpdu->actor_system = port->actor_system;
+	lacpdu->actor_key = port->actor_oper_port_key;
+	lacpdu->actor_port_priority = port->actor_port_priority;
+	lacpdu->actor_port = port->actor_port_number;
+	lacpdu->actor_state = port->actor_oper_port_state;
+
+	/* lacpdu->reserved_3_1              initialized
+	 * lacpdu->tlv_type_partner_info     initialized
+	 * lacpdu->partner_information_length initialized
+	 */
+
+	lacpdu->partner_system_priority = port->partner_oper_system_priority;
+	lacpdu->partner_system = port->partner_oper_system;
+	lacpdu->partner_key = port->partner_oper_key;
+	lacpdu->partner_port_priority = port->partner_oper_port_priority;
+	lacpdu->partner_port = port->partner_oper_port_number;
+	lacpdu->partner_state = port->partner_oper_port_state;
+
+	/* lacpdu->reserved_3_2              initialized
+	 * lacpdu->tlv_type_collector_info   initialized
+	 * lacpdu->collector_information_length initialized
+	 * collector_max_delay                initialized
+	 * reserved_12[12]                   initialized
+	 * tlv_type_terminator               initialized
+	 * terminator_length                 initialized
+	 * reserved_50[50]                   initialized
+	 */
+
+	/* Convert all non u8 parameters to Big Endian for transmit */
+	__ntohs_lacpdu(lacpdu);
+}
+
 //////////////////////////////////////////////////////////////////////////////////////
 // ================= main 802.3ad protocol code ======================================
 //////////////////////////////////////////////////////////////////////////////////////
@@ -1177,43 +1226,11 @@ static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port)
  */
 static void ad_tx_machine(struct port *port)
 {
-	struct lacpdu *lacpdu = &port->lacpdu;
-
 	// check if tx timer expired, to verify that we do not send more than 3 packets per second
 	if (port->sm_tx_timer_counter && !(--port->sm_tx_timer_counter)) {
 		// check if there is something to send
 		if (port->ntt && (port->sm_vars & AD_PORT_LACP_ENABLED)) {
-			//update current actual Actor parameters
-			//lacpdu->subtype                   initialized
-			//lacpdu->version_number            initialized
-			//lacpdu->tlv_type_actor_info       initialized
-			//lacpdu->actor_information_length  initialized
-			lacpdu->actor_system_priority = port->actor_system_priority;
-			lacpdu->actor_system = port->actor_system;
-			lacpdu->actor_key = port->actor_oper_port_key;
-			lacpdu->actor_port_priority = port->actor_port_priority;
-			lacpdu->actor_port = port->actor_port_number;
-			lacpdu->actor_state = port->actor_oper_port_state;
-			//lacpdu->reserved_3_1              initialized
-			//lacpdu->tlv_type_partner_info     initialized
-			//lacpdu->partner_information_length initialized
-			lacpdu->partner_system_priority = port->partner_oper_system_priority;
-			lacpdu->partner_system = port->partner_oper_system;
-			lacpdu->partner_key = port->partner_oper_key;
-			lacpdu->partner_port_priority = port->partner_oper_port_priority;
-			lacpdu->partner_port = port->partner_oper_port_number;
-			lacpdu->partner_state = port->partner_oper_port_state;
-			//lacpdu->reserved_3_2              initialized
-			//lacpdu->tlv_type_collector_info   initialized
-			//lacpdu->collector_information_length initialized
-			//collector_max_delay                initialized
-			//reserved_12[12]                   initialized
-			//tlv_type_terminator               initialized
-			//terminator_length                 initialized
-			//reserved_50[50]                   initialized
-
-			// We need to convert all non u8 parameters to Big Endian for transmit
-			__ntohs_lacpdu(lacpdu);
+			__update_lacpdu_from_port(port);
 			// send the lacpdu
 			if (ad_lacpdu_send(port) >= 0) {
 				BOND_PRINT_DBG(("Sent LACPDU on port %d", port->actor_port_number));
@@ -1971,13 +1988,13 @@ void bond_3ad_unbind_slave(struct slave *slave)
 		return;
 	}
 
-	// disable the port
-	ad_disable_collecting_distributing(port);
+	BOND_PRINT_DBG(("Unbinding Link Aggregation Group %d", aggregator->aggregator_identifier));
 
-	// deinitialize port's locks if necessary(os-specific)
-	__deinitialize_port_locks(port);
+	/* Tell the partner that this port is not suitable for aggregation */
+	port->actor_oper_port_state &= ~AD_STATE_AGGREGATION;
+	__update_lacpdu_from_port(port);
+	ad_lacpdu_send(port);
 
-	BOND_PRINT_DBG(("Unbinding Link Aggregation Group %d", aggregator->aggregator_identifier));
 	// check if this aggregator is occupied
 	if (aggregator->lag_ports) {
 		// check if there are other ports related to this aggregator except