net: Add ops->ndo_xmit_flush()

Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/dlci.c

@@ -193,7 +193,7 @@ static netdev_tx_t dlci_transmit(struct sk_buff *skb, struct net_device *dev)
 	struct dlci_local *dlp = netdev_priv(dev);
 
 	if (skb)
-		dlp->slave->netdev_ops->ndo_start_xmit(skb, dlp->slave);
+		netdev_start_xmit(skb, dlp->slave);
 	return NETDEV_TX_OK;
 }
 

drivers/usb/gadget/function/f_ncm.c

@@ -1101,7 +1101,7 @@ static void ncm_tx_tasklet(unsigned long data)
 	/* Only send if data is available. */
 	if (ncm->skb_tx_data) {
 		ncm->timer_force_tx = true;
-		ncm->netdev->netdev_ops->ndo_start_xmit(NULL, ncm->netdev);
+		netdev_start_xmit(NULL, ncm->netdev);
 		ncm->timer_force_tx = false;
 	}
 }

include/linux/netdevice.h

@@ -782,6 +782,19 @@ typedef u16 (*select_queue_fallback_t)(struct net_device *dev,
  *        (can also return NETDEV_TX_LOCKED iff NETIF_F_LLTX)
  *	Required can not be NULL.
  *
+ * void (*ndo_xmit_flush)(struct net_device *dev, u16 queue);
+ *	A driver implements this function when it wishes to support
+ *	deferred TX queue flushing.  The idea is that the expensive
+ *	operation to trigger TX queue processing can be done after
+ *	N calls to ndo_start_xmit rather than being done every single
+ *	time.  In this regime ndo_start_xmit will be called one or more
+ *	times, and then a final ndo_xmit_flush call will be made to
+ *	have the driver tell the device about the new pending TX queue
+ *	entries.  The kernel keeps track of which queues need flushing
+ *	by monitoring skb->queue_mapping of the packets it submits to
+ *	ndo_start_xmit.  This is the queue value that will be passed
+ *	to ndo_xmit_flush.
+ *
  * u16 (*ndo_select_queue)(struct net_device *dev, struct sk_buff *skb,
  *                         void *accel_priv, select_queue_fallback_t fallback);
  *	Called to decide which queue to when device supports multiple
@@ -1005,6 +1018,7 @@ struct net_device_ops {
 	int			(*ndo_stop)(struct net_device *dev);
 	netdev_tx_t		(*ndo_start_xmit) (struct sk_buff *skb,
 						   struct net_device *dev);
+	void			(*ndo_xmit_flush)(struct net_device *dev, u16 queue);
 	u16			(*ndo_select_queue)(struct net_device *dev,
 						    struct sk_buff *skb,
 						    void *accel_priv,
@@ -3430,6 +3444,27 @@ int __init dev_proc_init(void);
 #define dev_proc_init() 0
 #endif
 
+static inline netdev_tx_t __netdev_start_xmit(const struct net_device_ops *ops,
+					      struct sk_buff *skb, struct net_device *dev)
+{
+	netdev_tx_t ret;
+	u16 q;
+
+	q = skb->queue_mapping;
+	ret = ops->ndo_start_xmit(skb, dev);
+	if (dev_xmit_complete(ret) && ops->ndo_xmit_flush)
+		ops->ndo_xmit_flush(dev, q);
+
+	return ret;
+}
+
+static inline netdev_tx_t netdev_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	const struct net_device_ops *ops = dev->netdev_ops;
+
+	return __netdev_start_xmit(ops, skb, dev);
+}
+
 int netdev_class_create_file_ns(struct class_attribute *class_attr,
 				const void *ns);
 void netdev_class_remove_file_ns(struct class_attribute *class_attr,

net/atm/mpc.c

@@ -599,7 +599,7 @@ static netdev_tx_t mpc_send_packet(struct sk_buff *skb,
 	}
 
 non_ip:
-	return mpc->old_ops->ndo_start_xmit(skb, dev);
+	return __netdev_start_xmit(mpc->old_ops, skb, dev);
 }
 
 static int atm_mpoa_vcc_attach(struct atm_vcc *vcc, void __user *arg)

net/core/dev.c

@@ -2602,7 +2602,6 @@ EXPORT_SYMBOL(netif_skb_features);
 int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 			struct netdev_queue *txq)
 {
-	const struct net_device_ops *ops = dev->netdev_ops;
 	int rc = NETDEV_TX_OK;
 	unsigned int skb_len;
 
@@ -2667,7 +2666,7 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 
 		skb_len = skb->len;
 		trace_net_dev_start_xmit(skb, dev);
-		rc = ops->ndo_start_xmit(skb, dev);
+		rc = netdev_start_xmit(skb, dev);
 		trace_net_dev_xmit(skb, rc, dev, skb_len);
 		if (rc == NETDEV_TX_OK)
 			txq_trans_update(txq);
@@ -2686,7 +2685,7 @@ gso:
 
 		skb_len = nskb->len;
 		trace_net_dev_start_xmit(nskb, dev);
-		rc = ops->ndo_start_xmit(nskb, dev);
+		rc = netdev_start_xmit(nskb, dev);
 		trace_net_dev_xmit(nskb, rc, dev, skb_len);
 		if (unlikely(rc != NETDEV_TX_OK)) {
 			if (rc & ~NETDEV_TX_MASK)

net/core/netpoll.c

@@ -72,7 +72,6 @@ module_param(carrier_timeout, uint, 0644);
 static int netpoll_start_xmit(struct sk_buff *skb, struct net_device *dev,
 			      struct netdev_queue *txq)
 {
-	const struct net_device_ops *ops = dev->netdev_ops;
 	int status = NETDEV_TX_OK;
 	netdev_features_t features;
 
@@ -92,7 +91,7 @@ static int netpoll_start_xmit(struct sk_buff *skb, struct net_device *dev,
 		skb->vlan_tci = 0;
 	}
 
-	status = ops->ndo_start_xmit(skb, dev);
+	status = netdev_start_xmit(skb, dev);
 	if (status == NETDEV_TX_OK)
 		txq_trans_update(txq);
 

net/core/pktgen.c

@@ -3285,8 +3285,6 @@ static void pktgen_wait_for_skb(struct pktgen_dev *pkt_dev)
 static void pktgen_xmit(struct pktgen_dev *pkt_dev)
 {
 	struct net_device *odev = pkt_dev->odev;
-	netdev_tx_t (*xmit)(struct sk_buff *, struct net_device *)
-		= odev->netdev_ops->ndo_start_xmit;
 	struct netdev_queue *txq;
 	u16 queue_map;
 	int ret;
@@ -3339,7 +3337,7 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
 		goto unlock;
 	}
 	atomic_inc(&(pkt_dev->skb->users));
-	ret = (*xmit)(pkt_dev->skb, odev);
+	ret = netdev_start_xmit(pkt_dev->skb, odev);
 
 	switch (ret) {
 	case NETDEV_TX_OK:

net/packet/af_packet.c

@@ -240,7 +240,6 @@ static void __fanout_link(struct sock *sk, struct packet_sock *po);
 static int packet_direct_xmit(struct sk_buff *skb)
 {
 	struct net_device *dev = skb->dev;
-	const struct net_device_ops *ops = dev->netdev_ops;
 	netdev_features_t features;
 	struct netdev_queue *txq;
 	int ret = NETDEV_TX_BUSY;
@@ -262,7 +261,7 @@ static int packet_direct_xmit(struct sk_buff *skb)
 
 	HARD_TX_LOCK(dev, txq, smp_processor_id());
 	if (!netif_xmit_frozen_or_drv_stopped(txq)) {
-		ret = ops->ndo_start_xmit(skb, dev);
+		ret = netdev_start_xmit(skb, dev);
 		if (ret == NETDEV_TX_OK)
 			txq_trans_update(txq);
 	}

net/sched/sch_teql.c

@@ -301,7 +301,6 @@ restart:
 	do {
 		struct net_device *slave = qdisc_dev(q);
 		struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0);
-		const struct net_device_ops *slave_ops = slave->netdev_ops;
 
 		if (slave_txq->qdisc_sleeping != q)
 			continue;
@@ -317,7 +316,7 @@ restart:
 				unsigned int length = qdisc_pkt_len(skb);
 
 				if (!netif_xmit_frozen_or_stopped(slave_txq) &&
-				    slave_ops->ndo_start_xmit(skb, slave) == NETDEV_TX_OK) {
+				    netdev_start_xmit(skb, slave) == NETDEV_TX_OK) {
 					txq_trans_update(slave_txq);
 					__netif_tx_unlock(slave_txq);
 					master->slaves = NEXT_SLAVE(q);