mlxsw: spectrum: Add couple of lower device helper functions

Add functions that iterate over lower devices and find port device.
As a dependency add netdev_for_each_all_lower_dev and
netdev_for_each_all_lower_dev_rcu macro with
netdev_all_lower_get_next and netdev_all_lower_get_next_rcu shelpers.

Also, add functions to return mlxsw struct according to lower device
found and mlxsw_port struct with a reference to lower device.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 46 insertions, 0 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index aba10d2a8bc3..a4f3b0a9aeaf 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5445,6 +5445,52 @@ void *netdev_lower_get_next(struct net_device *dev, struct list_head **iter)
 EXPORT_SYMBOL(netdev_lower_get_next);
 
 /**
+ * netdev_all_lower_get_next - Get the next device from all lower neighbour list
+ * @dev: device
+ * @iter: list_head ** of the current position
+ *
+ * Gets the next netdev_adjacent from the dev's all lower neighbour
+ * list, starting from iter position. The caller must hold RTNL lock or
+ * its own locking that guarantees that the neighbour all lower
+ * list will remain unchanged.
+ */
+struct net_device *netdev_all_lower_get_next(struct net_device *dev, struct list_head **iter)
+{
+        struct netdev_adjacent *lower;
+
+        lower = list_entry(*iter, struct netdev_adjacent, list);
+
+        if (&lower->list == &dev->all_adj_list.lower)
+                return NULL;
+
+        *iter = lower->list.next;
+
+        return lower->dev;
+}
+EXPORT_SYMBOL(netdev_all_lower_get_next);
+
+/**
+ * netdev_all_lower_get_next_rcu - Get the next device from all
+ *                                 lower neighbour list, RCU variant
+ * @dev: device
+ * @iter: list_head ** of the current position
+ *
+ * Gets the next netdev_adjacent from the dev's all lower neighbour
+ * list, starting from iter position. The caller must hold RCU read lock.
+ */
+struct net_device *netdev_all_lower_get_next_rcu(struct net_device *dev,
+                                                 struct list_head **iter)
+{
+        struct netdev_adjacent *lower;
+
+        lower = list_first_or_null_rcu(&dev->all_adj_list.lower,
+                                       struct netdev_adjacent, list);
+
+        return lower ? lower->dev : NULL;
+}
+EXPORT_SYMBOL(netdev_all_lower_get_next_rcu);
+
+/**
  * netdev_lower_get_first_private_rcu - Get the first ->private from the
  *                                     lower neighbour list, RCU
  *                                     variant