netdevice: add queue selection fallback handler for ndo_select_queue

Add a new argument for ndo_select_queue() callback that passes a
fallback handler. This gets invoked through netdev_pick_tx();
fallback handler is currently __netdev_pick_tx() as most drivers
invoke this function within their customized implementation in
case for skbs that don't need any special handling. This fallback
handler can then be replaced on other call-sites with different
queue selection methods (e.g. in packet sockets, pktgen etc).

This also has the nice side-effect that __netdev_pick_tx() is
then only invoked from netdev_pick_tx() and export of that
function to modules can be undone.

Suggested-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 3 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 21d4e6be8949..1de9c136b066 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -752,6 +752,9 @@ struct netdev_phys_port_id {
         unsigned char id_len;
 };
 
+typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
+                                       struct sk_buff *skb);
+
 /*
  * This structure defines the management hooks for network devices.
  * The following hooks can be defined; unless noted otherwise, they are
@@ -783,7 +786,7 @@ struct netdev_phys_port_id {
  *      Required can not be NULL.
  *
  * u16 (*ndo_select_queue)(struct net_device *dev, struct sk_buff *skb,
- *                         void *accel_priv);
+ *                         void *accel_priv, select_queue_fallback_t fallback);
  *      Called to decide which queue to when device supports multiple
  *      transmit queues.
  *
@@ -1005,7 +1008,8 @@ struct net_device_ops {
                                                    struct net_device *dev);
         u16                     (*ndo_select_queue)(struct net_device *dev,
                                                     struct sk_buff *skb,
-                                                    void *accel_priv);
+                                                    void *accel_priv,
+                                                    select_queue_fallback_t fallback);
         void                    (*ndo_change_rx_flags)(struct net_device *dev,
                                                        int flags);
         void                    (*ndo_set_rx_mode)(struct net_device *dev);
@@ -1551,7 +1555,6 @@ static inline void netdev_for_each_tx_queue(struct net_device *dev,
 struct netdev_queue *netdev_pick_tx(struct net_device *dev,
                                     struct sk_buff *skb,
                                     void *accel_priv);
-u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb);
 
 /*
  * Net namespace inlines