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

From: David Ahern <[email-masked]>
Date: Mon, 16 Mar 2015 09:46:56 -0600

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 <[email-masked]>
Cc: Jiri Pirko <[email-masked]>
Cc: Scott Feldman <[email-masked]>
---
 include/linux/netdevice.h    | 13 +++++++++++++
 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, 76 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index dd1d069758be..47a773b9bee0 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -765,6 +765,15 @@ struct netdev_phys_item_id {
 	unsigned char id_len;
 };
 
+#define MAX_PHYS_ITEM_NAME_LEN 32
+
+/* This structure holds a unique name to identify some
+ * physical item (port for example) used by a netdevice.
+ */
+struct netdev_phys_item_name {
+	char str[MAX_PHYS_ITEM_NAME_LEN];
+};
+
 typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
 				       struct sk_buff *skb);
 
@@ -1159,6 +1168,8 @@ 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,
+							  struct netdev_phys_item_name *name);
 	void			(*ndo_add_vxlan_port)(struct  net_device *dev,
 						      sa_family_t sa_family,
 						      __be16 port);
@@ -2939,6 +2950,8 @@ 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,
+			   struct netdev_phys_item_name *name);
 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..38b04093e4c9 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,
+			   struct netdev_phys_item_name *name)
+{
+	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);
+}
+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..beecfd499341 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)) {
+		struct netdev_phys_item_name name;
+
+		ret = dev_get_phys_port_name(netdev, &name);
+		if (!ret)
+			ret = sprintf(buf, "%s\n", name.str);
+	}
+	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..6f4d17e13db7 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)
+{
+	struct netdev_phys_item_name name;
+	int err;
+
+	err = dev_get_phys_port_name(dev, &name);
+	if (err) {
+		if (err == -EOPNOTSUPP)
+			return 0;
+		return err;
+	}
+
+	if (nla_put(skb, IFLA_PHYS_PORT_NAME, strlen(name.str), name.str))
+		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