[PATCH net 1/2] bonding: 3ad: fix carrier when no valid slaves

[Louis Scalbert <louis.scalbert@6wind.com>]

When an 802.3ad (LACP) bonding interface has no slaves in the
collecting/distributing state, the bonding master may still report
carrier as up. In this situation, no slave is actually able to transmit
or receive traffic.

As a result, upper-layer daemons consider the interface operational
while traffic is effectively blackholed.

Fix this by asserting carrier only when at least 'min_links' slaves are
in the collecting/distributing state (or collecting only if the
coupled_control default behavior is disabled).

Fixes: 655f8919d549 ("bonding: add min links parameter to 802.3ad")
Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>
---
 drivers/net/bonding/bond_3ad.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index af7f74cfdc08..7d7661972c5e 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -745,6 +745,22 @@ static void __set_agg_ports_ready(struct aggregator *aggregator, int val)
 	}
 }
 
+static int __agg_valid_ports(struct aggregator *agg)
+{
+	struct port *port;
+	int valid = 0;
+
+	for (port = agg->lag_ports; port;
+	     port = port->next_port_in_aggregator) {
+		if (port->actor_oper_port_state & LACP_STATE_COLLECTING &&
+		    (!port->slave->bond->params.coupled_control ||
+		     port->actor_oper_port_state & LACP_STATE_DISTRIBUTING))
+			valid++;
+	}
+
+	return valid;
+}
+
 static int __agg_active_ports(struct aggregator *agg)
 {
 	struct port *port;
@@ -2120,6 +2136,7 @@ static void ad_enable_collecting_distributing(struct port *port,
 			  port->actor_port_number,
 			  port->aggregator->aggregator_identifier);
 		__enable_port(port);
+		bond_3ad_set_carrier(port->slave->bond);
 		/* Slave array needs update */
 		*update_slave_arr = true;
 		/* Should notify peers if possible */
@@ -2141,6 +2158,7 @@ static void ad_disable_collecting_distributing(struct port *port,
 			  port->actor_port_number,
 			  port->aggregator->aggregator_identifier);
 		__disable_port(port);
+		bond_3ad_set_carrier(port->slave->bond);
 		/* Slave array needs an update */
 		*update_slave_arr = true;
 	}
@@ -2819,8 +2837,8 @@ int bond_3ad_set_carrier(struct bonding *bond)
 	}
 	active = __get_active_agg(&(SLAVE_AD_INFO(first_slave)->aggregator));
 	if (active) {
-		/* are enough slaves available to consider link up? */
-		if (__agg_active_ports(active) < bond->params.min_links) {
+		/* are enough slaves in collecting (and distributing) state to consider link up? */
+		if (__agg_valid_ports(active) < bond->params.min_links) {
 			if (netif_carrier_ok(bond->dev)) {
 				netif_carrier_off(bond->dev);
 				goto out;
-- 
2.39.2