bonding: add primary attribute netlink support

Add IFLA_BOND_PRIMARY to allow get/set of bonding parameter
primary via netlink.

Signed-off-by: Scott Feldman <sfeldma@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
index 990793d..9445243 100644
--- a/drivers/net/bonding/bond_netlink.c
+++ b/drivers/net/bonding/bond_netlink.c
@@ -32,6 +32,7 @@
 	[IFLA_BOND_ARP_IP_TARGET]	= { .type = NLA_NESTED },
 	[IFLA_BOND_ARP_VALIDATE]	= { .type = NLA_U32 },
 	[IFLA_BOND_ARP_ALL_TARGETS]	= { .type = NLA_U32 },
+	[IFLA_BOND_PRIMARY]		= { .type = NLA_U32 },
 };
 
 static int bond_validate(struct nlattr *tb[], struct nlattr *data[])
@@ -154,6 +155,19 @@
 		if (err)
 			return err;
 	}
+	if (data[IFLA_BOND_PRIMARY]) {
+		int ifindex = nla_get_u32(data[IFLA_BOND_PRIMARY]);
+		struct net_device *dev;
+		char *primary = "";
+
+		dev = __dev_get_by_index(dev_net(bond_dev), ifindex);
+		if (dev)
+			primary = dev->name;
+
+		err = bond_option_primary_set(bond, primary);
+		if (err)
+			return err;
+	}
 	return 0;
 }
 
@@ -182,6 +196,7 @@
 		nla_total_size(sizeof(u32)) * BOND_MAX_ARP_TARGETS +
 		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_ARP_VALIDATE */
 		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_ARP_ALL_TARGETS */
+		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_PRIMARY */
 		0;
 }
 
@@ -241,6 +256,11 @@
 			bond->params.arp_all_targets))
 		goto nla_put_failure;
 
+	if (bond->primary_slave &&
+	    nla_put_u32(skb, IFLA_BOND_PRIMARY,
+			bond->primary_slave->dev->ifindex))
+		goto nla_put_failure;
+
 	return 0;
 
 nla_put_failure: