[PATCH net-next V3 1/8] net: netdevice: Add operation ndo_sk_get_lower_dev

[Tariq Toukan]

ndo_sk_get_lower_dev returns the lower netdev that corresponds to
a given socket.
Additionally, we implement a helper netdev_sk_get_lowest_dev() to get
the lowest one in chain.

Signed-off-by: Tariq Toukan <tar...@nvidia.com>
Reviewed-by: Boris Pismenny <bor...@nvidia.com>
---
 include/linux/netdevice.h |  4 ++++
 net/core/dev.c            | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5b949076ed23..02dcef4d66e2 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1398,6 +1398,8 @@ struct net_device_ops {
        struct net_device*      (*ndo_get_xmit_slave)(struct net_device *dev,
                                                      struct sk_buff *skb,
                                                      bool all_slaves);
+       struct net_device*      (*ndo_sk_get_lower_dev)(struct net_device *dev,
+                                                       struct sock *sk);
        netdev_features_t       (*ndo_fix_features)(struct net_device *dev,
                                                    netdev_features_t features);
        int                     (*ndo_set_features)(struct net_device *dev,
@@ -2858,6 +2860,8 @@ 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 *netdev_sk_get_lowest_dev(struct net_device *dev,
+                                           struct sock *sk);
 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 bae35c1ae192..6b90520a01b1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8105,6 +8105,39 @@ struct net_device *netdev_get_xmit_slave(struct 
net_device *dev,
 }
 EXPORT_SYMBOL(netdev_get_xmit_slave);
 
+static struct net_device *netdev_sk_get_lower_dev(struct net_device *dev,
+                                                 struct sock *sk)
+{
+       const struct net_device_ops *ops = dev->netdev_ops;
+
+       if (!ops->ndo_sk_get_lower_dev)
+               return NULL;
+       return ops->ndo_sk_get_lower_dev(dev, sk);
+}
+
+/**
+ * netdev_sk_get_lowest_dev - Get the lowest device in chain given device and 
socket
+ * @dev: device
+ * @sk: the socket
+ *
+ * %NULL is returned if no lower device is found.
+ */
+
+struct net_device *netdev_sk_get_lowest_dev(struct net_device *dev,
+                                           struct sock *sk)
+{
+       struct net_device *lower;
+
+       lower = netdev_sk_get_lower_dev(dev, sk);
+       while (lower) {
+               dev = lower;
+               lower = netdev_sk_get_lower_dev(dev, sk);
+       }
+
+       return dev;
+}
+EXPORT_SYMBOL(netdev_sk_get_lowest_dev);
+
 static void netdev_adjacent_add_links(struct net_device *dev)
 {
        struct netdev_adjacent *iter;
-- 
2.21.0