bonding: Implement port churn-machine (AD standard 43.4.17).

The Churn Detection machines detect the situation where a port is operable,
but the Actor and Partner have not attached the link to an Aggregator and
brought the link into operation within a bound time period. Under normal
operation of the LACP, agreement between Actor and Partner should be reached
very rapidly. Continued failure to reach agreement can be symptomatic of
device failure.

Actor-churn-detection state-machine
Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com>

===================================

BEGIN=True + PortEnable=False
           |
           v
 +------------------------+   ActorPort.Sync=True  +------------------+
 |   ACTOR_CHURN_MONITOR  | ---------------------> |  NO_ACTOR_CHURN  |
 |========================|                        |==================|
 |    ActorChurn=False    |  ActorPort.Sync=False  | ActorChurn=False |
 | ActorChurn.Timer=Start | <--------------------- |                  |
 +------------------------+                        +------------------+
           |                                                ^
           |                                                |
  ActorChurn.Timer=Expired                                  |
           |                                       ActorPort.Sync=True
           |                                                |
           |                +-----------------+             |
           |                |   ACTOR_CHURN   |             |
           |                |=================|             |
           +--------------> | ActorChurn=True | ------------+
                            |                 |
                            +-----------------+

Similar for the Partner-churn-detection.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 55 insertions, 2 deletions

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 9b436696b95e..f61b2870cddf 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -38,6 +38,7 @@
 #define AD_STANDBY                 0x2
 #define AD_MAX_TX_IN_SECOND        3
 #define AD_COLLECTOR_MAX_DELAY     0
+#define AD_MONITOR_CHURNED         0x1000
 
 /* Timer definitions (43.4.4 in the 802.3ad standard) */
 #define AD_FAST_PERIODIC_TIME      1
@@ -1013,16 +1014,19 @@ static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port)
 	/* check if state machine should change state */
 
 	/* first, check if port was reinitialized */
-	if (port->sm_vars & AD_PORT_BEGIN)
+	if (port->sm_vars & AD_PORT_BEGIN) {
 		port->sm_rx_state = AD_RX_INITIALIZE;
+		port->sm_vars |= AD_MONITOR_CHURNED;
 	/* check if port is not enabled */
-	else if (!(port->sm_vars & AD_PORT_BEGIN)
+	} else if (!(port->sm_vars & AD_PORT_BEGIN)
 		 && !port->is_enabled && !(port->sm_vars & AD_PORT_MOVED))
 		port->sm_rx_state = AD_RX_PORT_DISABLED;
 	/* check if new lacpdu arrived */
 	else if (lacpdu && ((port->sm_rx_state == AD_RX_EXPIRED) ||
 		 (port->sm_rx_state == AD_RX_DEFAULTED) ||
 		 (port->sm_rx_state == AD_RX_CURRENT))) {
+		if (port->sm_rx_state != AD_RX_CURRENT)
+			port->sm_vars |= AD_MONITOR_CHURNED;
 		port->sm_rx_timer_counter = 0;
 		port->sm_rx_state = AD_RX_CURRENT;
 	} else {
@@ -1100,9 +1104,11 @@ static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port)
 			 */
 			port->partner_oper.port_state &= ~AD_STATE_SYNCHRONIZATION;
 			port->sm_vars &= ~AD_PORT_MATCHED;
+			port->partner_oper.port_state |= AD_STATE_LACP_TIMEOUT;
 			port->partner_oper.port_state |= AD_STATE_LACP_ACTIVITY;
 			port->sm_rx_timer_counter = __ad_timer_to_ticks(AD_CURRENT_WHILE_TIMER, (u16)(AD_SHORT_TIMEOUT));
 			port->actor_oper_port_state |= AD_STATE_EXPIRED;
+			port->sm_vars |= AD_MONITOR_CHURNED;
 			break;
 		case AD_RX_DEFAULTED:
 			__update_default_selected(port);
@@ -1132,6 +1138,45 @@ static void ad_rx_machine(struct lacpdu *lacpdu, struct port *port)
 }
 
 /**
+ * ad_churn_machine - handle port churn's state machine
+ * @port: the port we're looking at
+ *
+ */
+static void ad_churn_machine(struct port *port)
+{
+	if (port->sm_vars & AD_MONITOR_CHURNED) {
+		port->sm_vars &= ~AD_MONITOR_CHURNED;
+		port->sm_churn_actor_state = AD_CHURN_MONITOR;
+		port->sm_churn_partner_state = AD_CHURN_MONITOR;
+		port->sm_churn_actor_timer_counter =
+			__ad_timer_to_ticks(AD_ACTOR_CHURN_TIMER, 0);
+		 port->sm_churn_partner_timer_counter =
+			 __ad_timer_to_ticks(AD_PARTNER_CHURN_TIMER, 0);
+		return;
+	}
+	if (port->sm_churn_actor_timer_counter &&
+	    !(--port->sm_churn_actor_timer_counter) &&
+	    port->sm_churn_actor_state == AD_CHURN_MONITOR) {
+		if (port->actor_oper_port_state & AD_STATE_SYNCHRONIZATION) {
+			port->sm_churn_actor_state = AD_NO_CHURN;
+		} else {
+			port->churn_actor_count++;
+			port->sm_churn_actor_state = AD_CHURN;
+		}
+	}
+	if (port->sm_churn_partner_timer_counter &&
+	    !(--port->sm_churn_partner_timer_counter) &&
+	    port->sm_churn_partner_state == AD_CHURN_MONITOR) {
+		if (port->partner_oper.port_state & AD_STATE_SYNCHRONIZATION) {
+			port->sm_churn_partner_state = AD_NO_CHURN;
+		} else {
+			port->churn_partner_count++;
+			port->sm_churn_partner_state = AD_CHURN;
+		}
+	}
+}
+
+/**
  * ad_tx_machine - handle a port's tx state machine
  * @port: the port we're looking at
  */
@@ -1745,6 +1790,13 @@ static void ad_initialize_port(struct port *port, int lacp_fast)
 		port->next_port_in_aggregator = NULL;
 		port->transaction_id = 0;
 
+		port->sm_churn_actor_timer_counter = 0;
+		port->sm_churn_actor_state = 0;
+		port->churn_actor_count = 0;
+		port->sm_churn_partner_timer_counter = 0;
+		port->sm_churn_partner_state = 0;
+		port->churn_partner_count = 0;
+
 		memcpy(&port->lacpdu, &lacpdu, sizeof(lacpdu));
 	}
 }
@@ -2164,6 +2216,7 @@ void bond_3ad_state_machine_handler(struct work_struct *work)
 		ad_port_selection_logic(port, &update_slave_arr);
 		ad_mux_machine(port, &update_slave_arr);
 		ad_tx_machine(port);
+		ad_churn_machine(port);
 
 		/* turn off the BEGIN bit, since we already handled it */
 		if (port->sm_vars & AD_PORT_BEGIN)