linux: Use fake carrier flag for netfront/netback rather than the real

netif_carrier_XXX() functions. This makes network bringup much faster.
Signed-off-by: Keir Fraser <keir@xensource.com>

5 files changed, 69 insertions, 44 deletions

diff --git a/linux-2.6-xen-sparse/drivers/xen/netback/common.h b/linux-2.6-xen-sparse/drivers/xen/netback/common.h
index 170d2772cf..861c5faeac 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/common.h
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/common.h
@@ -99,9 +99,21 @@ typedef struct netif_st {
 	struct net_device *dev;
 	struct net_device_stats stats;
 
+	unsigned int carrier;
+
 	wait_queue_head_t waiting_to_free;
 } netif_t;
 
+/*
+ * Implement our own carrier flag: the network stack's version causes delays
+ * when the carrier is re-enabled (in particular, dev_activate() may not
+ * immediately be called, which can cause packet loss; also the etherbridge
+ * can be rather lazy in activating its port).
+ */
+#define netback_carrier_on(netif)	((netif)->carrier = 1)
+#define netback_carrier_off(netif)	((netif)->carrier = 0)
+#define netback_carrier_ok(netif)	((netif)->carrier)
+
 #define NET_TX_RING_SIZE __RING_SIZE((netif_tx_sring_t *)0, PAGE_SIZE)
 #define NET_RX_RING_SIZE __RING_SIZE((netif_rx_sring_t *)0, PAGE_SIZE)
 
@@ -120,7 +132,8 @@ int netif_map(netif_t *netif, unsigned long tx_ring_ref,
 
 void netif_xenbus_init(void);
 
-#define netif_schedulable(dev) (netif_running(dev) && netif_carrier_ok(dev))
+#define netif_schedulable(netif)				\
+	(netif_running((netif)->dev) && netback_carrier_ok(netif))
 
 void netif_schedule_work(netif_t *netif);
 void netif_deschedule_work(netif_t *netif);
diff --git a/linux-2.6-xen-sparse/drivers/xen/netback/interface.c b/linux-2.6-xen-sparse/drivers/xen/netback/interface.c
index 8bf951117f..610891fc29 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/interface.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/interface.c
@@ -66,16 +66,19 @@ static void __netif_down(netif_t *netif)
 static int net_open(struct net_device *dev)
 {
 	netif_t *netif = netdev_priv(dev);
-	if (netif_carrier_ok(dev))
+	if (netback_carrier_ok(netif)) {
 		__netif_up(netif);
+		netif_start_queue(dev);
+	}
 	return 0;
 }
 
 static int net_close(struct net_device *dev)
 {
 	netif_t *netif = netdev_priv(dev);
-	if (netif_carrier_ok(dev))
+	if (netback_carrier_ok(netif))
 		__netif_down(netif);
+	netif_stop_queue(dev);
 	return 0;
 }
 
@@ -138,8 +141,6 @@ netif_t *netif_alloc(domid_t domid, unsigned int handle)
 		return ERR_PTR(-ENOMEM);
 	}
 
-	netif_carrier_off(dev);
-
 	netif = netdev_priv(dev);
 	memset(netif, 0, sizeof(*netif));
 	netif->domid  = domid;
@@ -148,6 +149,8 @@ netif_t *netif_alloc(domid_t domid, unsigned int handle)
 	init_waitqueue_head(&netif->waiting_to_free);
 	netif->dev = dev;
 
+	netback_carrier_off(netif);
+
 	netif->credit_bytes = netif->remaining_credit = ~0UL;
 	netif->credit_usec  = 0UL;
 	init_timer(&netif->credit_timeout);
@@ -285,7 +288,7 @@ int netif_map(netif_t *netif, unsigned long tx_ring_ref,
 	netif_get(netif);
 
 	rtnl_lock();
-	netif_carrier_on(netif->dev);
+	netback_carrier_on(netif);
 	if (netif_running(netif->dev))
 		__netif_up(netif);
 	rtnl_unlock();
@@ -302,9 +305,10 @@ err_rx:
 
 void netif_disconnect(netif_t *netif)
 {
-	if (netif_carrier_ok(netif->dev)) {
+	if (netback_carrier_ok(netif)) {
 		rtnl_lock();
-		netif_carrier_off(netif->dev);
+		netback_carrier_off(netif);
+		netif_carrier_off(netif->dev); /* discard queued packets */
 		if (netif_running(netif->dev))
 			__netif_down(netif);
 		rtnl_unlock();
diff --git a/linux-2.6-xen-sparse/drivers/xen/netback/netback.c b/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
index 837dd260ab..df72a6433a 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/netback.c
@@ -38,7 +38,7 @@
 #include <xen/balloon.h>
 #include <xen/interface/memory.h>
 
-/*#define NETBE_DEBUG_INTERRUPT*/
+#define NETBE_DEBUG_INTERRUPT
 
 /* extra field used in struct page */
 #define netif_page_index(pg) (*(long *)&(pg)->mapping)
@@ -234,7 +234,7 @@ static inline int netbk_queue_full(netif_t *netif)
 static void tx_queue_callback(unsigned long data)
 {
 	netif_t *netif = (netif_t *)data;
-	if (netif_schedulable(netif->dev))
+	if (netif_schedulable(netif))
 		netif_wake_queue(netif->dev);
 }
 
@@ -245,7 +245,7 @@ int netif_be_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	BUG_ON(skb->dev != dev);
 
 	/* Drop the packet if the target domain has no receive buffers. */
-	if (unlikely(!netif_schedulable(dev) || netbk_queue_full(netif)))
+	if (unlikely(!netif_schedulable(netif) || netbk_queue_full(netif)))
 		goto drop;
 
 	/*
@@ -684,7 +684,7 @@ static void net_rx_action(unsigned long unused)
 		}
 
 		if (netif_queue_stopped(netif->dev) &&
-		    netif_schedulable(netif->dev) &&
+		    netif_schedulable(netif) &&
 		    !netbk_queue_full(netif))
 			netif_wake_queue(netif->dev);
 
@@ -742,7 +742,7 @@ static void add_to_net_schedule_list_tail(netif_t *netif)
 
 	spin_lock_irq(&net_schedule_list_lock);
 	if (!__on_net_schedule_list(netif) &&
-	    likely(netif_schedulable(netif->dev))) {
+	    likely(netif_schedulable(netif))) {
 		list_add_tail(&netif->list, &net_schedule_list);
 		netif_get(netif);
 	}
@@ -1340,7 +1340,7 @@ irqreturn_t netif_be_int(int irq, void *dev_id, struct pt_regs *regs)
 	add_to_net_schedule_list_tail(netif);
 	maybe_schedule_tx_action();
 
-	if (netif_schedulable(netif->dev) && !netbk_queue_full(netif))
+	if (netif_schedulable(netif) && !netbk_queue_full(netif))
 		netif_wake_queue(netif->dev);
 
 	return IRQ_HANDLED;
diff --git a/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c b/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c
index 12a3dc26f8..50bc909309 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c
@@ -338,9 +338,7 @@ static void connect(struct backend_info *be)
 
 	xenbus_switch_state(dev, XenbusStateConnected);
 
-	/* May not get a kick from the frontend, so start the tx_queue now. */
-	if (!netbk_can_queue(be->netif->dev))
-		netif_wake_queue(be->netif->dev);
+	netif_wake_queue(be->netif->dev);
 }
 
 
diff --git a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
index ea503adfd0..17d1daf658 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
@@ -154,6 +154,7 @@ struct netfront_info {
 
 	unsigned int irq;
 	unsigned int copying_receiver;
+	unsigned int carrier;
 
 	/* Receive-ring batched refills. */
 #define RX_MIN_TARGET 8
@@ -193,6 +194,15 @@ struct netfront_rx_info {
 };
 
 /*
+ * Implement our own carrier flag: the network stack's version causes delays
+ * when the carrier is re-enabled (in particular, dev_activate() may not
+ * immediately be called, which can cause packet loss).
+ */
+#define netfront_carrier_on(netif)	((netif)->carrier = 1)
+#define netfront_carrier_off(netif)	((netif)->carrier = 0)
+#define netfront_carrier_ok(netif)	((netif)->carrier)
+
+/*
  * Access macros for acquiring freeing slots in tx_skbs[].
  */
 
@@ -590,6 +600,22 @@ static int send_fake_arp(struct net_device *dev)
 	return dev_queue_xmit(skb);
 }
 
+static inline int netfront_tx_slot_available(struct netfront_info *np)
+{
+	return ((np->tx.req_prod_pvt - np->tx.rsp_cons) <
+		(TX_MAX_TARGET - MAX_SKB_FRAGS - 2));
+}
+
+static inline void network_maybe_wake_tx(struct net_device *dev)
+{
+	struct netfront_info *np = netdev_priv(dev);
+
+	if (unlikely(netif_queue_stopped(dev)) &&
+	    netfront_tx_slot_available(np) &&
+	    likely(netif_running(dev)))
+		netif_wake_queue(dev);
+}
+
 static int network_open(struct net_device *dev)
 {
 	struct netfront_info *np = netdev_priv(dev);
@@ -597,7 +623,7 @@ static int network_open(struct net_device *dev)
 	memset(&np->stats, 0, sizeof(np->stats));
 
 	spin_lock(&np->rx_lock);
-	if (netif_carrier_ok(dev)) {
+	if (netfront_carrier_ok(np)) {
 		network_alloc_rx_buffers(dev);
 		np->rx.sring->rsp_event = np->rx.rsp_cons + 1;
 		if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
@@ -605,27 +631,11 @@ static int network_open(struct net_device *dev)
 	}
 	spin_unlock(&np->rx_lock);
 
-	netif_start_queue(dev);
+	network_maybe_wake_tx(dev);
 
 	return 0;
 }
 
-static inline int netfront_tx_slot_available(struct netfront_info *np)
-{
-	return ((np->tx.req_prod_pvt - np->tx.rsp_cons) <
-		(TX_MAX_TARGET - MAX_SKB_FRAGS - 2));
-}
-
-static inline void network_maybe_wake_tx(struct net_device *dev)
-{
-	struct netfront_info *np = netdev_priv(dev);
-
-	if (unlikely(netif_queue_stopped(dev)) &&
-	    netfront_tx_slot_available(np) &&
-	    likely(netif_running(dev)))
-		netif_wake_queue(dev);
-}
-
 static void network_tx_buf_gc(struct net_device *dev)
 {
 	RING_IDX cons, prod;
@@ -633,7 +643,7 @@ static void network_tx_buf_gc(struct net_device *dev)
 	struct netfront_info *np = netdev_priv(dev);
 	struct sk_buff *skb;
 
-	BUG_ON(!netif_carrier_ok(dev));
+	BUG_ON(!netfront_carrier_ok(np));
 
 	do {
 		prod = np->tx.sring->rsp_prod;
@@ -703,7 +713,7 @@ static void network_alloc_rx_buffers(struct net_device *dev)
 	int nr_flips;
 	netif_rx_request_t *req;
 
-	if (unlikely(!netif_carrier_ok(dev)))
+	if (unlikely(!netfront_carrier_ok(np)))
 		return;
 
 	/*
@@ -934,7 +944,7 @@ static int network_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	spin_lock_irq(&np->tx_lock);
 
-	if (unlikely(!netif_carrier_ok(dev) ||
+	if (unlikely(!netfront_carrier_ok(np) ||
 		     (frags > 1 && !xennet_can_sg(dev)) ||
 		     netif_needs_gso(dev, skb))) {
 		spin_unlock_irq(&np->tx_lock);
@@ -1024,7 +1034,7 @@ static irqreturn_t netif_int(int irq, void *dev_id, struct pt_regs *ptregs)
 
 	spin_lock_irqsave(&np->tx_lock, flags);
 
-	if (likely(netif_carrier_ok(dev))) {
+	if (likely(netfront_carrier_ok(np))) {
 		network_tx_buf_gc(dev);
 		/* Under tx_lock: protects access to rx shared-ring indexes. */
 		if (RING_HAS_UNCONSUMED_RESPONSES(&np->rx))
@@ -1299,7 +1309,7 @@ static int netif_poll(struct net_device *dev, int *pbudget)
 
 	spin_lock(&np->rx_lock);
 
-	if (unlikely(!netif_carrier_ok(dev))) {
+	if (unlikely(!netfront_carrier_ok(np))) {
 		spin_unlock(&np->rx_lock);
 		return 0;
 	}
@@ -1317,7 +1327,7 @@ static int netif_poll(struct net_device *dev, int *pbudget)
 	work_done = 0;
 	while ((i != rp) && (work_done < budget)) {
 		memcpy(rx, RING_GET_RESPONSE(&np->rx, i), sizeof(*rx));
-		memset(extras, 0, sizeof(extras));
+		memset(extras, 0, sizeof(rinfo.extras));
 
 		err = xennet_get_responses(np, &rinfo, rp, &tmpq,
 					   &pages_flipped);
@@ -1744,7 +1754,7 @@ static int network_connect(struct net_device *dev)
 	 * domain a kick because we've probably just requeued some
 	 * packets.
 	 */
-	netif_carrier_on(dev);
+	netfront_carrier_on(np);
 	notify_remote_via_irq(np->irq);
 	network_tx_buf_gc(dev);
 	network_alloc_rx_buffers(dev);
@@ -1989,7 +1999,7 @@ static struct net_device * __devinit create_netdev(struct xenbus_device *dev)
 
 	np->netdev = netdev;
 
-	netif_carrier_off(netdev);
+	netfront_carrier_off(np);
 
 	return netdev;
 
@@ -2023,7 +2033,7 @@ static void netif_disconnect_backend(struct netfront_info *info)
 	/* Stop old i/f to prevent errors whilst we rebuild the state. */
 	spin_lock_irq(&info->tx_lock);
 	spin_lock(&info->rx_lock);
-	netif_carrier_off(info->netdev);
+	netfront_carrier_off(info);
 	spin_unlock(&info->rx_lock);
 	spin_unlock_irq(&info->tx_lock);