net: add change_carrier netdev op

This allows a driver to register change_carrier callback which will be
called whenever user will like to change carrier state. This is useful
for devices like dummy, gre, team and so on.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 31 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c599e4782d45..0e1b92a0c1ec 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -891,6 +891,14 @@ struct netdev_fcoe_hbainfo {
  * int (*ndo_bridge_setlink)(struct net_device *dev, struct nlmsghdr *nlh)
  * int (*ndo_bridge_getlink)(struct sk_buff *skb, u32 pid, u32 seq,
  *                           struct net_device *dev)
+ *
+ * int (*ndo_change_carrier)(struct net_device *dev, bool new_carrier);
+ *      Called to change device carrier. Soft-devices (like dummy, team, etc)
+ *      which do not represent real hardware may define this to allow their
+ *      userspace components to manage their virtual carrier state. Devices
+ *      that determine carrier state from physical hardware properties (eg
+ *      network cables) or protocol-dependent mechanisms (eg
+ *      USB_CDC_NOTIFY_NETWORK_CONNECTION) should NOT implement this function.
  */
 struct net_device_ops {
         int                     (*ndo_init)(struct net_device *dev);
@@ -1008,6 +1016,8 @@ struct net_device_ops {
         int                     (*ndo_bridge_getlink)(struct sk_buff *skb,
                                                       u32 pid, u32 seq,
                                                       struct net_device *dev);
+        int                     (*ndo_change_carrier)(struct net_device *dev,
+                                                      bool new_carrier);
 };
 
 /*
@@ -2194,6 +2204,8 @@ extern int		dev_set_mtu(struct net_device *, int);
 extern void             dev_set_group(struct net_device *, int);
 extern int              dev_set_mac_address(struct net_device *,
                                             struct sockaddr *);
+extern int              dev_change_carrier(struct net_device *,
+                                           bool new_carrier);
 extern int              dev_hard_start_xmit(struct sk_buff *skb,
                                             struct net_device *dev,
                                             struct netdev_queue *txq);
diff --git a/net/core/dev.c b/net/core/dev.c
index 515473ee52cb..21c5b976dcf3 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5027,6 +5027,25 @@ int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa)
 }
 EXPORT_SYMBOL(dev_set_mac_address);
 
+/**
+ *      dev_change_carrier - Change device carrier
+ *      @dev: device
+ *      @new_carries: new value
+ *
+ *      Change device carrier
+ */
+int dev_change_carrier(struct net_device *dev, bool new_carrier)
+{
+        const struct net_device_ops *ops = dev->netdev_ops;
+
+        if (!ops->ndo_change_carrier)
+                return -EOPNOTSUPP;
+        if (!netif_device_present(dev))
+                return -ENODEV;
+        return ops->ndo_change_carrier(dev, new_carrier);
+}
+EXPORT_SYMBOL(dev_change_carrier);
+
 /*
  *      Perform the SIOCxIFxxx calls, inside rcu_read_lock()
  */