net: remove 'fallback' argument from dev->ndo_select_queue()

After the previous patch, all the callers of ndo_select_queue()
provide as a 'fallback' argument netdev_pick_tx.
The only exceptions are nested calls to ndo_select_queue(),
which pass down the 'fallback' available in the current scope
- still netdev_pick_tx.

We can drop such argument and replace fallback() invocation with
netdev_pick_tx(). This avoids an indirect call per xmit packet
in some scenarios (TCP syn, UDP unconnected, XDP generic, pktgen)
with device drivers implementing such ndo. It also clean the code
a bit.

Tested with ixgbe and CONFIG_FCOE=m

With pktgen using queue xmit:
threads		vanilla 	patched
		(kpps)		(kpps)
1		2334		2428
2		4166		4278
4		7895		8100

 v1 -> v2:
 - rebased after helper's name change

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 6 insertions, 12 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 1a76b4fe9b97..357111431ec9 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3689,16 +3689,14 @@ get_cpus_map:
 }
 
 u16 dev_pick_tx_zero(struct net_device *dev, struct sk_buff *skb,
-                     struct net_device *sb_dev,
-                     select_queue_fallback_t fallback)
+                     struct net_device *sb_dev)
 {
         return 0;
 }
 EXPORT_SYMBOL(dev_pick_tx_zero);
 
 u16 dev_pick_tx_cpu_id(struct net_device *dev, struct sk_buff *skb,
-                       struct net_device *sb_dev,
-                       select_queue_fallback_t fallback)
+                       struct net_device *sb_dev)
 {
         return (u16)raw_smp_processor_id() % dev->real_num_tx_queues;
 }
@@ -3748,8 +3746,7 @@ struct netdev_queue *netdev_core_pick_tx(struct net_device *dev,
                 const struct net_device_ops *ops = dev->netdev_ops;
 
                 if (ops->ndo_select_queue)
-                        queue_index = ops->ndo_select_queue(dev, skb, sb_dev,
-                                                            netdev_pick_tx);
+                        queue_index = ops->ndo_select_queue(dev, skb, sb_dev);
                 else
                         queue_index = netdev_pick_tx(dev, skb, sb_dev);
 
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 4a6ff1482a9f..f0d97eba250b 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1133,8 +1133,7 @@ static void ieee80211_uninit(struct net_device *dev)
 
 static u16 ieee80211_netdev_select_queue(struct net_device *dev,
                                          struct sk_buff *skb,
-                                         struct net_device *sb_dev,
-                                         select_queue_fallback_t fallback)
+                                         struct net_device *sb_dev)
 {
         return ieee80211_select_queue(IEEE80211_DEV_TO_SUB_IF(dev), skb);
 }
@@ -1179,8 +1178,7 @@ static const struct net_device_ops ieee80211_dataif_ops = {
 
 static u16 ieee80211_monitor_select_queue(struct net_device *dev,
                                           struct sk_buff *skb,
-                                          struct net_device *sb_dev,
-                                          select_queue_fallback_t fallback)
+                                          struct net_device *sb_dev)
 {
         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
         struct ieee80211_local *local = sdata->local;
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index a8809dc0e1ab..741953b42f44 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -287,8 +287,7 @@ static u16 packet_pick_tx_queue(struct sk_buff *skb)
 #endif
         skb_record_rx_queue(skb, cpu % dev->real_num_tx_queues);
         if (ops->ndo_select_queue) {
-                queue_index = ops->ndo_select_queue(dev, skb, NULL,
-                                                    netdev_pick_tx);
+                queue_index = ops->ndo_select_queue(dev, skb, NULL);
                 queue_index = netdev_cap_txqueue(dev, queue_index);
         } else {
                 queue_index = netdev_pick_tx(dev, skb, NULL);