bridge: implement rtnl_link_ops->get_size and rtnl_link_ops->fill_info

Allow rtnetlink users to get bridge master info in IFLA_INFO_DATA attr
This initial part implements forward_delay, hello_time, max_age options.
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_link.h

@@ -215,6 +215,18 @@ enum in6_addr_gen_mode {
 	IN6_ADDR_GEN_MODE_NONE,
 };
 
+/* Bridge section */
+
+enum {
+	IFLA_BR_UNSPEC,
+	IFLA_BR_FORWARD_DELAY,
+	IFLA_BR_HELLO_TIME,
+	IFLA_BR_MAX_AGE,
+	__IFLA_BR_MAX,
+};
+
+#define IFLA_BR_MAX	(__IFLA_BR_MAX - 1)
+
 enum {
 	BRIDGE_MODE_UNSPEC,
 	BRIDGE_MODE_HAIRPIN,

net/bridge/br_netlink.c

@@ -484,6 +484,29 @@ static size_t br_port_get_slave_size(const struct net_device *brdev,
 	return br_port_info_size();
 }
 
+static size_t br_get_size(const struct net_device *brdev)
+{
+	return nla_total_size(sizeof(u32)) +	/* IFLA_BR_FORWARD_DELAY  */
+	       nla_total_size(sizeof(u32)) +	/* IFLA_BR_HELLO_TIME */
+	       nla_total_size(sizeof(u32)) +	/* IFLA_BR_MAX_AGE */
+	       0;
+}
+
+static int br_fill_info(struct sk_buff *skb, const struct net_device *brdev)
+{
+	struct net_bridge *br = netdev_priv(brdev);
+	u32 forward_delay = jiffies_to_clock_t(br->forward_delay);
+	u32 hello_time = jiffies_to_clock_t(br->hello_time);
+	u32 age_time = jiffies_to_clock_t(br->max_age);
+
+	if (nla_put_u32(skb, IFLA_BR_FORWARD_DELAY, forward_delay) ||
+	    nla_put_u32(skb, IFLA_BR_HELLO_TIME, hello_time) ||
+	    nla_put_u32(skb, IFLA_BR_MAX_AGE, age_time))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
 static size_t br_get_link_af_size(const struct net_device *dev)
 {
 	struct net_port_vlans *pv;
@@ -514,6 +537,8 @@ struct rtnl_link_ops br_link_ops __read_mostly = {
 	.validate		= br_validate,
 	.newlink		= br_dev_newlink,
 	.dellink		= br_dev_delete,
+	.get_size		= br_get_size,
+	.fill_info		= br_fill_info,
 
 	.slave_maxtype		= IFLA_BRPORT_MAX,
 	.slave_policy		= br_port_policy,