[NET]: Make NAPI polling independent of struct net_device objects.

Several devices have multiple independant RX queues per net
device, and some have a single interrupt doorbell for several
queues.

In either case, it's easier to support layouts like that if the
structure representing the poll is independant from the net
device itself.

The signature of the ->poll() call back goes from:

	int foo_poll(struct net_device *dev, int *budget)

to

	int foo_poll(struct napi_struct *napi, int budget)

The caller is returned the number of RX packets processed (or
the number of "NAPI credits" consumed if you want to get
abstract).  The callee no longer messes around bumping
dev->quota, *budget, etc. because that is all handled in the
caller upon return.

The napi_struct is to be embedded in the device driver private data
structures.

Furthermore, it is the driver's responsibility to disable all NAPI
instances in it's ->stop() device close handler.  Since the
napi_struct is privatized into the driver's private data structures,
only the driver knows how to get at all of the napi_struct instances
it may have per-device.

With lots of help and suggestions from Rusty Russell, Roland Dreier,
Michael Chan, Jeff Garzik, and Jamal Hadi Salim.

Bug fixes from Thomas Graf, Roland Dreier, Peter Zijlstra,
Joseph Fannin, Scott Wood, Hans J. Koch, and Michael Chan.

[ Ported to current tree and all drivers converted.  Integrated
  Stephen's follow-on kerneldoc additions, and restored poll_list
  handling to the old style to fix mutual exclusion issues.  -DaveM ]

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 16 deletions

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 4445810..70e551c 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -72,6 +72,7 @@ struct netfront_info {
 	struct list_head list;
 	struct net_device *netdev;
 
+	struct napi_struct napi;
 	struct net_device_stats stats;
 
 	struct xen_netif_tx_front_ring tx;
@@ -185,7 +186,8 @@ static int xennet_can_sg(struct net_device *dev)
 static void rx_refill_timeout(unsigned long data)
 {
 	struct net_device *dev = (struct net_device *)data;
-	netif_rx_schedule(dev);
+	struct netfront_info *np = netdev_priv(dev);
+	netif_rx_schedule(dev, &np->napi);
 }
 
 static int netfront_tx_slot_available(struct netfront_info *np)
@@ -342,12 +344,14 @@ static int xennet_open(struct net_device *dev)
 
 	memset(&np->stats, 0, sizeof(np->stats));
 
+	napi_enable(&np->napi);
+
 	spin_lock_bh(&np->rx_lock);
 	if (netif_carrier_ok(dev)) {
 		xennet_alloc_rx_buffers(dev);
 		np->rx.sring->rsp_event = np->rx.rsp_cons + 1;
 		if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
-			netif_rx_schedule(dev);
+			netif_rx_schedule(dev, &np->napi);
 	}
 	spin_unlock_bh(&np->rx_lock);
 
@@ -589,6 +593,7 @@ static int xennet_close(struct net_device *dev)
 {
 	struct netfront_info *np = netdev_priv(dev);
 	netif_stop_queue(np->netdev);
+	napi_disable(&np->napi);
 	return 0;
 }
 
@@ -872,15 +877,16 @@ static int handle_incoming_queue(struct net_device *dev,
 	return packets_dropped;
 }
 
-static int xennet_poll(struct net_device *dev, int *pbudget)
+static int xennet_poll(struct napi_struct *napi, int budget)
 {
-	struct netfront_info *np = netdev_priv(dev);
+	struct netfront_info *np = container_of(napi, struct netfront_info, napi);
+	struct net_device *dev = np->netdev;
 	struct sk_buff *skb;
 	struct netfront_rx_info rinfo;
 	struct xen_netif_rx_response *rx = &rinfo.rx;
 	struct xen_netif_extra_info *extras = rinfo.extras;
 	RING_IDX i, rp;
-	int work_done, budget, more_to_do = 1;
+	int work_done;
 	struct sk_buff_head rxq;
 	struct sk_buff_head errq;
 	struct sk_buff_head tmpq;
@@ -899,9 +905,6 @@ static int xennet_poll(struct net_device *dev, int *pbudget)
 	skb_queue_head_init(&errq);
 	skb_queue_head_init(&tmpq);
 
-	budget = *pbudget;
-	if (budget > dev->quota)
-		budget = dev->quota;
 	rp = np->rx.sring->rsp_prod;
 	rmb(); /* Ensure we see queued responses up to 'rp'. */
 
@@ -1006,22 +1009,21 @@ err:
 
 	xennet_alloc_rx_buffers(dev);
 
-	*pbudget   -= work_done;
-	dev->quota -= work_done;
-
 	if (work_done < budget) {
+		int more_to_do = 0;
+
 		local_irq_save(flags);
 
 		RING_FINAL_CHECK_FOR_RESPONSES(&np->rx, more_to_do);
 		if (!more_to_do)
-			__netif_rx_complete(dev);
+			__netif_rx_complete(dev, napi);
 
 		local_irq_restore(flags);
 	}
 
 	spin_unlock(&np->rx_lock);
 
-	return more_to_do;
+	return work_done;
 }
 
 static int xennet_change_mtu(struct net_device *dev, int mtu)
@@ -1201,10 +1203,9 @@ static struct net_device * __devinit xennet_create_dev(struct xenbus_device *dev
 	netdev->hard_start_xmit = xennet_start_xmit;
 	netdev->stop            = xennet_close;
 	netdev->get_stats       = xennet_get_stats;
-	netdev->poll            = xennet_poll;
+	netif_napi_add(netdev, &np->napi, xennet_poll, 64);
 	netdev->uninit          = xennet_uninit;
 	netdev->change_mtu	= xennet_change_mtu;
-	netdev->weight          = 64;
 	netdev->features        = NETIF_F_IP_CSUM;
 
 	SET_ETHTOOL_OPS(netdev, &xennet_ethtool_ops);
@@ -1349,7 +1350,7 @@ static irqreturn_t xennet_interrupt(int irq, void *dev_id)
 		xennet_tx_buf_gc(dev);
 		/* Under tx_lock: protects access to rx shared-ring indexes. */
 		if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
-			netif_rx_schedule(dev);
+			netif_rx_schedule(dev, &np->napi);
 	}
 
 	spin_unlock_irqrestore(&np->tx_lock, flags);