net core: Add protodown support.

This patch introduces the proto_down flag that can be used by user space
applications to notify switch drivers that errors have been detected on the
device.

The switch driver can react to protodown notification by doing a phys down
on the associated switch port.
Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>
Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Wilson Kok <wkok@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1041,6 +1041,12 @@ typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
  *	TX queue.
  * int (*ndo_get_iflink)(const struct net_device *dev);
  *	Called to get the iflink value of this device.
+ * void (*ndo_change_proto_down)(struct net_device *dev,
+ *				  bool proto_down);
+ *	This function is used to pass protocol port error state information
+ *	to the switch driver. The switch driver can react to the proto_down
+ *      by doing a phys down on the associated switch port.
+ *
  */
 struct net_device_ops {
 	int			(*ndo_init)(struct net_device *dev);
@@ -1211,6 +1217,8 @@ struct net_device_ops {
 						      int queue_index,
 						      u32 maxrate);
 	int			(*ndo_get_iflink)(const struct net_device *dev);
+	int			(*ndo_change_proto_down)(struct net_device *dev,
+							 bool proto_down);
 };
 
 /**
@@ -1502,6 +1510,10 @@ enum netdev_priv_flags {
  *
  *	@qdisc_tx_busylock:	XXX: need comments on this one
  *
+ *	@proto_down:	protocol port state information can be sent to the
+ *			switch driver and used to set the phys state of the
+ *			switch port.
+ *
  *	FIXME: cleanup struct net_device such that network protocol info
  *	moves out.
  */
@@ -1762,6 +1774,7 @@ struct net_device {
 #endif
 	struct phy_device *phydev;
 	struct lock_class_key *qdisc_tx_busylock;
+	bool proto_down;
 };
 #define to_net_dev(d) container_of(d, struct net_device, dev)
 
@@ -2982,6 +2995,7 @@ 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);
+int dev_change_proto_down(struct net_device *dev, bool proto_down);
 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);

net/core/dev.c

@@ -6074,6 +6074,26 @@ int dev_get_phys_port_name(struct net_device *dev,
 }
 EXPORT_SYMBOL(dev_get_phys_port_name);
 
+/**
+ *	dev_change_proto_down - update protocol port state information
+ *	@dev: device
+ *	@proto_down: new value
+ *
+ *	This info can be used by switch drivers to set the phys state of the
+ *	port.
+ */
+int dev_change_proto_down(struct net_device *dev, bool proto_down)
+{
+	const struct net_device_ops *ops = dev->netdev_ops;
+
+	if (!ops->ndo_change_proto_down)
+		return -EOPNOTSUPP;
+	if (!netif_device_present(dev))
+		return -ENODEV;
+	return ops->ndo_change_proto_down(dev, proto_down);
+}
+EXPORT_SYMBOL(dev_change_proto_down);
+
 /**
  *	dev_new_index	-	allocate an ifindex
  *	@net: the applicable net namespace

net/core/net-sysfs.c

@@ -404,6 +404,19 @@ static ssize_t group_store(struct device *dev, struct device_attribute *attr,
 NETDEVICE_SHOW(group, fmt_dec);
 static DEVICE_ATTR(netdev_group, S_IRUGO | S_IWUSR, group_show, group_store);
 
+static int change_proto_down(struct net_device *dev, unsigned long proto_down)
+{
+	return dev_change_proto_down(dev, (bool) proto_down);
+}
+
+static ssize_t proto_down_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t len)
+{
+	return netdev_store(dev, attr, buf, len, change_proto_down);
+}
+NETDEVICE_SHOW_RW(proto_down, fmt_dec);
+
 static ssize_t phys_port_id_show(struct device *dev,
 				 struct device_attribute *attr, char *buf)
 {
@@ -501,6 +514,7 @@ static struct attribute *net_class_attrs[] = {
 	&dev_attr_phys_port_id.attr,
 	&dev_attr_phys_port_name.attr,
 	&dev_attr_phys_switch_id.attr,
+	&dev_attr_proto_down.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(net_class);