[NET] back: Simplify probing of new interfaces. There's no need

to watch for creation of the handle node in xenstore, as it is
written by xend when creating the backend directory as part of
the same transaction.
Signed-off-by: Keir Fraser <keir@xensource.com>

3 files changed, 33 insertions, 80 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 434ff6bcf2..34dd998663 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/common.h
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/common.h
@@ -106,7 +106,7 @@ typedef struct netif_st {
 
 void netif_disconnect(netif_t *netif);
 
-netif_t *netif_alloc(domid_t domid, unsigned int handle, u8 be_mac[ETH_ALEN]);
+netif_t *netif_alloc(domid_t domid, unsigned int handle);
 int netif_map(netif_t *netif, unsigned long tx_ring_ref,
 	      unsigned long rx_ring_ref, unsigned int evtchn);
 
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 d70955fd1b..a698ccc77b 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/interface.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/interface.c
@@ -126,7 +126,7 @@ static struct ethtool_ops network_ethtool_ops =
 	.get_link = ethtool_op_get_link,
 };
 
-netif_t *netif_alloc(domid_t domid, unsigned int handle, u8 be_mac[ETH_ALEN])
+netif_t *netif_alloc(domid_t domid, unsigned int handle)
 {
 	int err = 0, i;
 	struct net_device *dev;
@@ -169,20 +169,14 @@ netif_t *netif_alloc(domid_t domid, unsigned int handle, u8 be_mac[ETH_ALEN])
 		printk(KERN_WARNING "netbk: WARNING: device '%s' has non-zero "
 		       "queue length (%lu)!\n", dev->name, dev->tx_queue_len);
 
-	for (i = 0; i < ETH_ALEN; i++)
-		if (be_mac[i] != 0)
-			break;
-	if (i == ETH_ALEN) {
-		/*
-		 * Initialise a dummy MAC address. We choose the numerically
-		 * largest non-broadcast address to prevent the address getting
-		 * stolen by an Ethernet bridge for STP purposes.
-		 * (FE:FF:FF:FF:FF:FF)
-		 */ 
-		memset(dev->dev_addr, 0xFF, ETH_ALEN);
-		dev->dev_addr[0] &= ~0x01;
-	} else
-		memcpy(dev->dev_addr, be_mac, ETH_ALEN);
+	/*
+	 * Initialise a dummy MAC address. We choose the numerically
+	 * largest non-broadcast address to prevent the address getting
+	 * stolen by an Ethernet bridge for STP purposes.
+	 * (FE:FF:FF:FF:FF:FF)
+	 */ 
+	memset(dev->dev_addr, 0xFF, ETH_ALEN);
+	dev->dev_addr[0] &= ~0x01;
 
 	rtnl_lock();
 	err = register_netdevice(dev);
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 8592ab4cb4..c61821c8f9 100644
--- a/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c
@@ -28,29 +28,20 @@
     printk("netback/xenbus (%s:%d) " fmt ".\n", __FUNCTION__, __LINE__, ##args)
 #endif
 
-struct backend_info
-{
+struct backend_info {
 	struct xenbus_device *dev;
 	netif_t *netif;
-	struct xenbus_watch backend_watch;
 	enum xenbus_state frontend_state;
 };
 
 static int connect_rings(struct backend_info *);
 static void connect(struct backend_info *);
-static void maybe_connect(struct backend_info *);
-static void backend_changed(struct xenbus_watch *, const char **,
-			    unsigned int);
+static void backend_create_netif(struct backend_info *be);
 
 static int netback_remove(struct xenbus_device *dev)
 {
 	struct backend_info *be = dev->dev.driver_data;
 
-	if (be->backend_watch.node) {
-		unregister_xenbus_watch(&be->backend_watch);
-		kfree(be->backend_watch.node);
-		be->backend_watch.node = NULL;
-	}
 	if (be->netif) {
 		netif_disconnect(be->netif);
 		be->netif = NULL;
@@ -63,8 +54,7 @@ static int netback_remove(struct xenbus_device *dev)
 
 /**
  * Entry point to this code when a new device is created.  Allocate the basic
- * structures, and watch the store waiting for the hotplug scripts to tell us
- * the device's handle.  Switch to InitWait.
+ * structures and switch to InitWait.
  */
 static int netback_probe(struct xenbus_device *dev,
 			 const struct xenbus_device_id *id)
@@ -83,11 +73,6 @@ static int netback_probe(struct xenbus_device *dev,
 	be->dev = dev;
 	dev->dev.driver_data = be;
 
-	err = xenbus_watch_path2(dev, dev->nodename, "handle",
-				 &be->backend_watch, backend_changed);
-	if (err)
-		goto fail;
-
 	do {
 		err = xenbus_transaction_start(&xbt);
 		if (err) {
@@ -108,7 +93,8 @@ static int netback_probe(struct xenbus_device *dev,
 			goto abort_transaction;
 		}
 
-		err = xenbus_printf(xbt, dev->nodename, "feature-rx-copy", "%d", 1);
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-rx-copy", "%d", 1);
 		if (err) {
 			message = "writing feature-copying";
 			goto abort_transaction;
@@ -123,9 +109,11 @@ static int netback_probe(struct xenbus_device *dev,
 	}
 
 	err = xenbus_switch_state(dev, XenbusStateInitWait);
-	if (err) {
+	if (err)
 		goto fail;
-	}
+
+	/* This kicks hotplug scripts, so do it immediately. */
+	backend_create_netif(be);
 
 	return 0;
 
@@ -175,48 +163,30 @@ static int netback_uevent(struct xenbus_device *xdev, char **envp,
 }
 
 
-/**
- * Callback received when the hotplug scripts have placed the handle node.
- * Read it, and create a netif structure.  If the frontend is ready, connect.
- */
-static void backend_changed(struct xenbus_watch *watch,
-			    const char **vec, unsigned int len)
+static void backend_create_netif(struct backend_info *be)
 {
 	int err;
 	long handle;
-	struct backend_info *be
-		= container_of(watch, struct backend_info, backend_watch);
 	struct xenbus_device *dev = be->dev;
 
-	DPRINTK("");
+	if (be->netif != NULL)
+		return;
 
 	err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%li", &handle);
-	if (XENBUS_EXIST_ERR(err)) {
-		/* Since this watch will fire once immediately after it is
-		   registered, we expect this.  Ignore it, and wait for the
-		   hotplug scripts. */
-		return;
-	}
 	if (err != 1) {
 		xenbus_dev_fatal(dev, err, "reading handle");
 		return;
 	}
 
-	if (be->netif == NULL) {
-		u8 be_mac[ETH_ALEN] = { 0, 0, 0, 0, 0, 0 };
-
-		be->netif = netif_alloc(dev->otherend_id, handle, be_mac);
-		if (IS_ERR(be->netif)) {
-			err = PTR_ERR(be->netif);
-			be->netif = NULL;
-			xenbus_dev_fatal(dev, err, "creating interface");
-			return;
-		}
-
-		kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
-
-		maybe_connect(be);
+	be->netif = netif_alloc(dev->otherend_id, handle);
+	if (IS_ERR(be->netif)) {
+		err = PTR_ERR(be->netif);
+		be->netif = NULL;
+		xenbus_dev_fatal(dev, err, "creating interface");
+		return;
 	}
+
+	kobject_uevent(&dev->dev.kobj, KOBJ_ONLINE);
 }
 
 
@@ -249,11 +219,9 @@ static void frontend_changed(struct xenbus_device *dev,
 		break;
 
 	case XenbusStateConnected:
-		if (!be->netif) {
-			/* reconnect: setup be->netif */
-			backend_changed(&be->backend_watch, NULL, 0);
-		}
-		maybe_connect(be);
+		backend_create_netif(be);
+		if (be->netif)
+			connect(be);
 		break;
 
 	case XenbusStateClosing:
@@ -279,15 +247,6 @@ static void frontend_changed(struct xenbus_device *dev,
 }
 
 
-/* ** Connection ** */
-
-
-static void maybe_connect(struct backend_info *be)
-{
-	if (be->netif && (be->frontend_state == XenbusStateConnected))
-		connect(be);
-}
-
 static void xen_net_read_rate(struct xenbus_device *dev,
 			      unsigned long *bytes, unsigned long *usec)
 {