bonding: add min links parameter to 802.3ad

This adds support for a configuring the minimum number of links that
must be active before asserting carrier. It is similar to the Cisco
EtherChannel min-links feature. This allows setting the minimum number
of member ports that must be up (link-up state) before marking the
bond device as up (carrier on). This is useful for situations where
higher level services such as clustering want to ensure a minimum
number of low bandwidth links are active before switchover.

See:
   http://bugzilla.vyatta.com/show_bug.cgi?id=7196

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
index 77da2e849623..a047eb973e3b 100644
--- a/drivers/net/bonding/bond_3ad.c
+++ b/drivers/net/bonding/bond_3ad.c
@@ -2342,8 +2342,17 @@ void bond_3ad_handle_link_change(struct slave *slave, char link)
  */
 int bond_3ad_set_carrier(struct bonding *bond)
 {
-        if (__get_active_agg(&(SLAVE_AD_INFO(bond->first_slave).aggregator))) {
-                if (!netif_carrier_ok(bond->dev)) {
+        struct aggregator *active;
+
+        active = __get_active_agg(&(SLAVE_AD_INFO(bond->first_slave).aggregator));
+        if (active) {
+                /* are enough slaves available to consider link up? */
+                if (active->num_of_ports < bond->params.min_links) {
+                        if (netif_carrier_ok(bond->dev)) {
+                                netif_carrier_off(bond->dev);
+                                return 1;
+                        }
+                } else if (!netif_carrier_ok(bond->dev)) {
                         netif_carrier_on(bond->dev);
                         return 1;
                 }