net: add support for phys_port_name

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.

Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 23 insertions, 0 deletions

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 7e58bd7..cc5cf68 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,
 };