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>

2 files changed, 7 insertions, 6 deletions

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 87577d447554..75fe83f590ea 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -372,7 +372,7 @@ static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
 #endif
 }
 
-u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
+static u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
 {
         struct sock *sk = skb->sk;
         int queue_index = sk_tx_queue_get(sk);
@@ -392,7 +392,6 @@ u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
 
         return queue_index;
 }
-EXPORT_SYMBOL(__netdev_pick_tx);
 
 struct netdev_queue *netdev_pick_tx(struct net_device *dev,
                                     struct sk_buff *skb,
@@ -403,8 +402,8 @@ struct netdev_queue *netdev_pick_tx(struct net_device *dev,
         if (dev->real_num_tx_queues != 1) {
                 const struct net_device_ops *ops = dev->netdev_ops;
                 if (ops->ndo_select_queue)
-                        queue_index = ops->ndo_select_queue(dev, skb,
-                                                            accel_priv);
+                        queue_index = ops->ndo_select_queue(dev, skb, accel_priv,
+                                                            __netdev_pick_tx);
                 else
                         queue_index = __netdev_pick_tx(dev, skb);
 
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index d6d1f1df9119..ce1c44370610 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1057,7 +1057,8 @@ static void ieee80211_uninit(struct net_device *dev)
 
 static u16 ieee80211_netdev_select_queue(struct net_device *dev,
                                          struct sk_buff *skb,
-                                         void *accel_priv)
+                                         void *accel_priv,
+                                         select_queue_fallback_t fallback)
 {
         return ieee80211_select_queue(IEEE80211_DEV_TO_SUB_IF(dev), skb);
 }
@@ -1075,7 +1076,8 @@ static const struct net_device_ops ieee80211_dataif_ops = {
 
 static u16 ieee80211_monitor_select_queue(struct net_device *dev,
                                           struct sk_buff *skb,
-                                          void *accel_priv)
+                                          void *accel_priv,
+                                          select_queue_fallback_t fallback)
 {
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
         struct ieee80211_local *local = sdata->local;