net: expose devlink port over rtnetlink

Expose devlink port handle related to netdev over rtnetlink. Introduce a
new nested IFLA attribute to carry the info. Call into devlink code to
fill-up the nest with existing devlink attributes that are used over
devlink netlink.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/devlink.h

@@ -1873,6 +1873,9 @@ int devlink_compat_phys_port_name_get(struct net_device *dev,
 int devlink_compat_switch_id_get(struct net_device *dev,
 				 struct netdev_phys_item_id *ppid);
 
+int devlink_nl_port_handle_fill(struct sk_buff *msg, struct devlink_port *devlink_port);
+size_t devlink_nl_port_handle_size(struct devlink_port *devlink_port);
+
 #else
 
 static inline struct devlink *devlink_try_get(struct devlink *devlink)
@@ -1909,6 +1912,17 @@ devlink_compat_switch_id_get(struct net_device *dev,
 	return -EOPNOTSUPP;
 }
 
+static inline int
+devlink_nl_port_handle_fill(struct sk_buff *msg, struct devlink_port *devlink_port)
+{
+	return 0;
+}
+
+static inline size_t devlink_nl_port_handle_size(struct devlink_port *devlink_port)
+{
+	return 0;
+}
+
 #endif
 
 #endif /* _NET_DEVLINK_H_ */

include/uapi/linux/if_link.h

@@ -372,6 +372,8 @@ enum {
 	IFLA_TSO_MAX_SEGS,
 	IFLA_ALLMULTI,		/* Allmulti count: > 0 means acts ALLMULTI */
 
+	IFLA_DEVLINK_PORT,
+
 	__IFLA_MAX
 };
 

net/core/devlink.c

@@ -880,6 +880,24 @@ static int devlink_nl_put_nested_handle(struct sk_buff *msg, struct devlink *dev
 	return -EMSGSIZE;
 }
 
+int devlink_nl_port_handle_fill(struct sk_buff *msg, struct devlink_port *devlink_port)
+{
+	if (devlink_nl_put_handle(msg, devlink_port->devlink))
+		return -EMSGSIZE;
+	if (nla_put_u32(msg, DEVLINK_ATTR_PORT_INDEX, devlink_port->index))
+		return -EMSGSIZE;
+	return 0;
+}
+
+size_t devlink_nl_port_handle_size(struct devlink_port *devlink_port)
+{
+	struct devlink *devlink = devlink_port->devlink;
+
+	return nla_total_size(strlen(devlink->dev->bus->name) + 1) /* DEVLINK_ATTR_BUS_NAME */
+	     + nla_total_size(strlen(dev_name(devlink->dev)) + 1) /* DEVLINK_ATTR_DEV_NAME */
+	     + nla_total_size(4); /* DEVLINK_ATTR_PORT_INDEX */
+}
+
 struct devlink_reload_combination {
 	enum devlink_reload_action action;
 	enum devlink_reload_limit limit;

net/core/rtnetlink.c

@@ -53,6 +53,7 @@
 #include <net/fib_rules.h>
 #include <net/rtnetlink.h>
 #include <net/net_namespace.h>
+#include <net/devlink.h>
 
 #include "dev.h"
 
@@ -1038,6 +1039,16 @@ static size_t rtnl_proto_down_size(const struct net_device *dev)
 	return size;
 }
 
+static size_t rtnl_devlink_port_size(const struct net_device *dev)
+{
+	size_t size = nla_total_size(0); /* nest IFLA_DEVLINK_PORT */
+
+	if (dev->devlink_port)
+		size += devlink_nl_port_handle_size(dev->devlink_port);
+
+	return size;
+}
+
 static noinline size_t if_nlmsg_size(const struct net_device *dev,
 				     u32 ext_filter_mask)
 {
@@ -1091,6 +1102,7 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
 	       + nla_total_size(4)  /* IFLA_MAX_MTU */
 	       + rtnl_prop_list_size(dev)
 	       + nla_total_size(MAX_ADDR_LEN) /* IFLA_PERM_ADDRESS */
+	       + rtnl_devlink_port_size(dev)
 	       + 0;
 }
 
@@ -1728,6 +1740,30 @@ static int rtnl_fill_proto_down(struct sk_buff *skb,
 	return -EMSGSIZE;
 }
 
+static int rtnl_fill_devlink_port(struct sk_buff *skb,
+				  const struct net_device *dev)
+{
+	struct nlattr *devlink_port_nest;
+	int ret;
+
+	devlink_port_nest = nla_nest_start(skb, IFLA_DEVLINK_PORT);
+	if (!devlink_port_nest)
+		return -EMSGSIZE;
+
+	if (dev->devlink_port) {
+		ret = devlink_nl_port_handle_fill(skb, dev->devlink_port);
+		if (ret < 0)
+			goto nest_cancel;
+	}
+
+	nla_nest_end(skb, devlink_port_nest);
+	return 0;
+
+nest_cancel:
+	nla_nest_cancel(skb, devlink_port_nest);
+	return ret;
+}
+
 static int rtnl_fill_ifinfo(struct sk_buff *skb,
 			    struct net_device *dev, struct net *src_net,
 			    int type, u32 pid, u32 seq, u32 change,
@@ -1865,6 +1901,9 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
 			   dev->dev.parent->bus->name))
 		goto nla_put_failure;
 
+	if (rtnl_fill_devlink_port(skb, dev))
+		goto nla_put_failure;
+
 	nlmsg_end(skb, nlh);
 	return 0;