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, 33 insertions, 0 deletions

diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index 03d1196b844d..b60835f58650 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/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,
 };