[PATCH V4 mlx5-next 01/15] net/core: Introduce netdev_get_xmit_slave

[Maor Gottlieb <maorg@mellanox.com>]

Add new ndo to get the xmit slave of master device.
Caller should call dev_put() when it no longer works with
slave netdevice.
User can ask to get the xmit slave assume all the slaves can
transmit by set all_slaves arg to true.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
---
 include/linux/netdevice.h |  6 ++++++
 net/core/dev.c            | 30 ++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 130a668049ab..d1206f08e099 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1389,6 +1389,9 @@ struct net_device_ops {
 						 struct netlink_ext_ack *extack);
 	int			(*ndo_del_slave)(struct net_device *dev,
 						 struct net_device *slave_dev);
+	struct net_device*	(*ndo_get_xmit_slave)(struct net_device *dev,
+						      struct sk_buff *skb,
+						      bool all_slaves);
 	netdev_features_t	(*ndo_fix_features)(struct net_device *dev,
 						    netdev_features_t features);
 	int			(*ndo_set_features)(struct net_device *dev,
@@ -2731,6 +2734,9 @@ void netdev_freemem(struct net_device *dev);
 void synchronize_net(void);
 int init_dummy_netdev(struct net_device *dev);
 
+struct net_device *netdev_get_xmit_slave(struct net_device *dev,
+					 struct sk_buff *skb,
+					 bool all_slaves);
 struct net_device *dev_get_by_index(struct net *net, int ifindex);
 struct net_device *__dev_get_by_index(struct net *net, int ifindex);
 struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
diff --git a/net/core/dev.c b/net/core/dev.c
index 9c9e763bfe0e..294553551ba5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7785,6 +7785,36 @@ void netdev_bonding_info_change(struct net_device *dev,
 }
 EXPORT_SYMBOL(netdev_bonding_info_change);
 
+/**
+ * netdev_get_xmit_slave - Get the xmit slave of master device
+ * @skb: The packet
+ * @all_slaves: assume all the slaves are active
+ *
+ * This can be called from any context and does its own locking.
+ * The returned handle has the usage count incremented and the caller must
+ * use dev_put() to release it when it is no longer needed.
+ * %NULL is returned if no slave is found.
+ */
+
+struct net_device *netdev_get_xmit_slave(struct net_device *dev,
+					 struct sk_buff *skb,
+					 bool all_slaves)
+{
+	const struct net_device_ops *ops = dev->netdev_ops;
+	struct net_device *slave_dev;
+
+	if (!ops->ndo_get_xmit_slave)
+		return NULL;
+
+	rcu_read_lock();
+	slave_dev = ops->ndo_get_xmit_slave(dev, skb, all_slaves);
+	if (slave_dev)
+		dev_hold(slave_dev);
+	rcu_read_unlock();
+	return slave_dev;
+}
+EXPORT_SYMBOL(netdev_get_xmit_slave);
+
 static void netdev_adjacent_add_links(struct net_device *dev)
 {
 	struct netdev_adjacent *iter;
-- 
2.17.2