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[Xen-changelog] [xen-3.0.3-testing] [NET] back: Simplify probing of new interfaces. There's no need



# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1160755827 -3600
# Node ID efea4c3b8bccda8ec040e73e9a15f1d741a35cc5
# Parent  d2f13c8b081999b05e5137e2387c6291a1e59e05
[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@xxxxxxxxxxxxx>
---
 linux-2.6-xen-sparse/drivers/xen/netback/common.h    |    2 
 linux-2.6-xen-sparse/drivers/xen/netback/interface.c |   24 +----
 linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c    |   89 +++++--------------
 3 files changed, 34 insertions(+), 81 deletions(-)

diff -r d2f13c8b0819 -r efea4c3b8bcc 
linux-2.6-xen-sparse/drivers/xen/netback/common.h
--- a/linux-2.6-xen-sparse/drivers/xen/netback/common.h Fri Oct 13 17:07:39 
2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/common.h Fri Oct 13 17:10:27 
2006 +0100
@@ -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 -r d2f13c8b0819 -r efea4c3b8bcc 
linux-2.6-xen-sparse/drivers/xen/netback/interface.c
--- a/linux-2.6-xen-sparse/drivers/xen/netback/interface.c      Fri Oct 13 
17:07:39 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/interface.c      Fri Oct 13 
17:10:27 2006 +0100
@@ -126,7 +126,7 @@ static struct ethtool_ops network_ethtoo
        .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, unsi
                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 -r d2f13c8b0819 -r efea4c3b8bcc 
linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c
--- a/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c Fri Oct 13 17:07:39 
2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c Fri Oct 13 17:10:27 
2006 +0100
@@ -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_
 
 /**
  * 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_d
        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_d
                        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_d
        }
 
        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_
 }
 
 
-/**
- * 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 xenb
                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 xenb
 }
 
 
-/* ** 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)
 {

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