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>

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;
 		}

drivers/net/bonding/bond_main.c

@@ -98,6 +98,7 @@ static char *mode;
 static char *primary;
 static char *primary_reselect;
 static char *lacp_rate;
+static int min_links;
 static char *ad_select;
 static char *xmit_hash_policy;
 static int arp_interval = BOND_LINK_ARP_INTERV;
@@ -150,6 +151,9 @@ module_param(ad_select, charp, 0);
 MODULE_PARM_DESC(ad_select, "803.ad aggregation selection logic; "
 			    "0 for stable (default), 1 for bandwidth, "
 			    "2 for count");
+module_param(min_links, int, 0);
+MODULE_PARM_DESC(min_links, "Minimum number of available links before turning on carrier");
+
 module_param(xmit_hash_policy, charp, 0);
 MODULE_PARM_DESC(xmit_hash_policy, "balance-xor and 802.3ad hashing method; "
 				   "0 for layer 2 (default), 1 for layer 3+4, "
@@ -4798,6 +4802,7 @@ static int bond_check_params(struct bond_params *params)
 	params->tx_queues = tx_queues;
 	params->all_slaves_active = all_slaves_active;
 	params->resend_igmp = resend_igmp;
+	params->min_links = min_links;
 
 	if (primary) {
 		strncpy(params->primary, primary, IFNAMSIZ);

drivers/net/bonding/bond_procfs.c

@@ -125,6 +125,7 @@ static void bond_info_show_master(struct seq_file *seq)
 		seq_puts(seq, "\n802.3ad info\n");
 		seq_printf(seq, "LACP rate: %s\n",
 			   (bond->params.lacp_fast) ? "fast" : "slow");
+		seq_printf(seq, "Min links: %d\n", bond->params.min_links);
 		seq_printf(seq, "Aggregator selection policy (ad_select): %s\n",
 			   ad_select_tbl[bond->params.ad_select].modename);
 

drivers/net/bonding/bond_sysfs.c

@@ -819,6 +819,38 @@ out:
 static DEVICE_ATTR(lacp_rate, S_IRUGO | S_IWUSR,
 		   bonding_show_lacp, bonding_store_lacp);
 
+static ssize_t bonding_show_min_links(struct device *d,
+				      struct device_attribute *attr,
+				      char *buf)
+{
+	struct bonding *bond = to_bond(d);
+
+	return sprintf(buf, "%d\n", bond->params.min_links);
+}
+
+static ssize_t bonding_store_min_links(struct device *d,
+				       struct device_attribute *attr,
+				       const char *buf, size_t count)
+{
+	struct bonding *bond = to_bond(d);
+	int ret;
+	unsigned int new_value;
+
+	ret = kstrtouint(buf, 0, &new_value);
+	if (ret < 0) {
+		pr_err("%s: Ignoring invalid min links value %s.\n",
+		       bond->dev->name, buf);
+		return ret;
+	}
+
+	pr_info("%s: Setting min links value to %u\n",
+		bond->dev->name, new_value);
+	bond->params.min_links = new_value;
+	return count;
+}
+static DEVICE_ATTR(min_links, S_IRUGO | S_IWUSR,
+		   bonding_show_min_links, bonding_store_min_links);
+
 static ssize_t bonding_show_ad_select(struct device *d,
 				      struct device_attribute *attr,
 				      char *buf)
@@ -1601,6 +1633,7 @@ static struct attribute *per_bond_attrs[] = {
 	&dev_attr_queue_id.attr,
 	&dev_attr_all_slaves_active.attr,
 	&dev_attr_resend_igmp.attr,
+	&dev_attr_min_links.attr,
 	NULL,
 };
 

drivers/net/bonding/bonding.h

@@ -147,6 +147,7 @@ struct bond_params {
 	int updelay;
 	int downdelay;
 	int lacp_fast;
+	unsigned int min_links;
 	int ad_select;
 	char primary[IFNAMSIZ];
 	int primary_reselect;