netdevice: move netdev_cap_txqueue for shared usage to header

In order to allow users to invoke netdev_cap_txqueue, it needs to
be moved into netdevice.h header file. While at it, also add kernel
doc header to document the API.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -2278,6 +2278,26 @@ static inline void netdev_reset_queue(struct net_device *dev_queue)
 	netdev_tx_reset_queue(netdev_get_tx_queue(dev_queue, 0));
 }
 
+/**
+ * 	netdev_cap_txqueue - check if selected tx queue exceeds device queues
+ * 	@dev: network device
+ * 	@queue_index: given tx queue index
+ *
+ * 	Returns 0 if given tx queue index >= number of device tx queues,
+ * 	otherwise returns the originally passed tx queue index.
+ */
+static inline u16 netdev_cap_txqueue(struct net_device *dev, u16 queue_index)
+{
+	if (unlikely(queue_index >= dev->real_num_tx_queues)) {
+		net_warn_ratelimited("%s selects TX queue %d, but real number of TX queues is %d\n",
+				     dev->name, queue_index,
+				     dev->real_num_tx_queues);
+		return 0;
+	}
+
+	return queue_index;
+}
+
 /**
  *	netif_running - test if up
  *	@dev: network device

net/core/flow_dissector.c

@@ -323,17 +323,6 @@ u32 __skb_get_poff(const struct sk_buff *skb)
 	return poff;
 }
 
-static inline u16 dev_cap_txqueue(struct net_device *dev, u16 queue_index)
-{
-	if (unlikely(queue_index >= dev->real_num_tx_queues)) {
-		net_warn_ratelimited("%s selects TX queue %d, but real number of TX queues is %d\n",
-				     dev->name, queue_index,
-				     dev->real_num_tx_queues);
-		return 0;
-	}
-	return queue_index;
-}
-
 static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
 {
 #ifdef CONFIG_XPS
@@ -408,7 +397,7 @@ struct netdev_queue *netdev_pick_tx(struct net_device *dev,
 			queue_index = __netdev_pick_tx(dev, skb);
 
 		if (!accel_priv)
-			queue_index = dev_cap_txqueue(dev, queue_index);
+			queue_index = netdev_cap_txqueue(dev, queue_index);
 	}
 
 	skb_set_queue_mapping(skb, queue_index);