[PATCH v3 1/3] net: add support for phys_port_name

[David Ahern <dsahern@gmail.com>]

Similar to port id allow netdevices to specify port names and export
the name via sysfs. Drivers can implement the netdevice operation to
assist udev in having sane default names for the devices using the
rule:

$ cat /etc/udev/rules.d/80-net-setup-link.rules
SUBSYSTEM=="net", ACTION=="add", ATTR{phys_port_name}!="",
NAME="$attr{phys_port_name}"

Use of phys_name versus phys_id was suggested-by Jiri Pirko.

v3:
- changed length from int to size_t, variable name from buf to name per
  Jiri's comment

v2:
- replaced netdev_phys_item_name with buffer and length per Jiri's comment

Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Scott Feldman <sfeldma@gmail.com>
---
 include/linux/netdevice.h    |  4 ++++
 include/uapi/linux/if_link.h |  1 +
 net/core/dev.c               | 18 ++++++++++++++++++
 net/core/net-sysfs.c         | 23 +++++++++++++++++++++++
 net/core/rtnetlink.c         | 21 +++++++++++++++++++++
 5 files changed, 67 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index dd1d069758be..52b519b408e6 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1159,6 +1159,8 @@ struct net_device_ops {
 						      bool new_carrier);
 	int			(*ndo_get_phys_port_id)(struct net_device *dev,
 							struct netdev_phys_item_id *ppid);
+	int			(*ndo_get_phys_port_name)(struct net_device *dev,
+							  char *name, size_t len);
 	void			(*ndo_add_vxlan_port)(struct  net_device *dev,
 						      sa_family_t sa_family,
 						      __be16 port);
@@ -2939,6 +2941,8 @@ int dev_set_mac_address(struct net_device *, struct sockaddr *);
 int dev_change_carrier(struct net_device *, bool new_carrier);
 int dev_get_phys_port_id(struct net_device *dev,
 			 struct netdev_phys_item_id *ppid);
+int dev_get_phys_port_name(struct net_device *dev,
+			   char *name, size_t len);
 struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *dev);
 struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 				    struct netdev_queue *txq, int *ret);
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 756436e1ce89..7158fd00a109 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -147,6 +147,7 @@ enum {
 	IFLA_CARRIER_CHANGES,
 	IFLA_PHYS_SWITCH_ID,
 	IFLA_LINK_NETNSID,
+	IFLA_PHYS_PORT_NAME,
 	__IFLA_MAX
 };
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 39fe369b46ad..a1f24151db5b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5912,6 +5912,24 @@ int dev_get_phys_port_id(struct net_device *dev,
 EXPORT_SYMBOL(dev_get_phys_port_id);
 
 /**
+ *	dev_get_phys_port_name - Get device physical port name
+ *	@dev: device
+ *	@name: port name
+ *
+ *	Get device physical port name
+ */
+int dev_get_phys_port_name(struct net_device *dev,
+			   char *name, size_t len)
+{
+	const struct net_device_ops *ops = dev->netdev_ops;
+
+	if (!ops->ndo_get_phys_port_name)
+		return -EOPNOTSUPP;
+	return ops->ndo_get_phys_port_name(dev, name, len);
+}
+EXPORT_SYMBOL(dev_get_phys_port_name);
+
+/**
  *	dev_new_index	-	allocate an ifindex
  *	@net: the applicable net namespace
  *
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index cf30620a88e1..b2a673870c4b 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -418,6 +418,28 @@ static ssize_t phys_port_id_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(phys_port_id);
 
+static ssize_t phys_port_name_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct net_device *netdev = to_net_dev(dev);
+	ssize_t ret = -EINVAL;
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	if (dev_isalive(netdev)) {
+		char name[IFNAMSIZ];
+
+		ret = dev_get_phys_port_name(netdev, name, sizeof(name));
+		if (!ret)
+			ret = sprintf(buf, "%s\n", name);
+	}
+	rtnl_unlock();
+
+	return ret;
+}
+static DEVICE_ATTR_RO(phys_port_name);
+
 static ssize_t phys_switch_id_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
@@ -465,6 +487,7 @@ static struct attribute *net_class_attrs[] = {
 	&dev_attr_tx_queue_len.attr,
 	&dev_attr_gro_flush_timeout.attr,
 	&dev_attr_phys_port_id.attr,
+	&dev_attr_phys_port_name.attr,
 	&dev_attr_phys_switch_id.attr,
 	NULL,
 };
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 25b4b5d23485..6abe634c666c 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -982,6 +982,24 @@ static int rtnl_phys_port_id_fill(struct sk_buff *skb, struct net_device *dev)
 	return 0;
 }
 
+static int rtnl_phys_port_name_fill(struct sk_buff *skb, struct net_device *dev)
+{
+	char name[IFNAMSIZ];
+	int err;
+
+	err = dev_get_phys_port_name(dev, name, sizeof(name));
+	if (err) {
+		if (err == -EOPNOTSUPP)
+			return 0;
+		return err;
+	}
+
+	if (nla_put(skb, IFLA_PHYS_PORT_NAME, strlen(name), name))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
 static int rtnl_phys_switch_id_fill(struct sk_buff *skb, struct net_device *dev)
 {
 	int err;
@@ -1072,6 +1090,9 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
 	if (rtnl_phys_port_id_fill(skb, dev))
 		goto nla_put_failure;
 
+	if (rtnl_phys_port_name_fill(skb, dev))
+		goto nla_put_failure;
+
 	if (rtnl_phys_switch_id_fill(skb, dev))
 		goto nla_put_failure;
 
-- 
2.2.1