6 files changed, 696 insertions, 314 deletions

diff --git a/drivers/xen/xenbus/Makefile b/drivers/xen/xenbus/Makefile
index 5571f5b84223..8dca685358b4 100644
--- a/drivers/xen/xenbus/Makefile
+++ b/drivers/xen/xenbus/Makefile
@@ -5,3 +5,8 @@ xenbus-objs += xenbus_client.o
 xenbus-objs += xenbus_comms.o
 xenbus-objs += xenbus_xs.o
 xenbus-objs += xenbus_probe.o
+
+xenbus-be-objs-$(CONFIG_XEN_BACKEND) += xenbus_probe_backend.o
+xenbus-objs += $(xenbus-be-objs-y)
+
+obj-$(CONFIG_XEN_XENBUS_FRONTEND) += xenbus_probe_frontend.o
diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 7e49527189b6..cdacf923e073 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -50,6 +50,8 @@ const char *xenbus_strstate(enum xenbus_state state)
                 [ XenbusStateConnected    ] = "Connected",
                 [ XenbusStateClosing      ] = "Closing",
                 [ XenbusStateClosed       ] = "Closed",
+                [XenbusStateReconfiguring] = "Reconfiguring",
+                [XenbusStateReconfigured] = "Reconfigured",
         };
         return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
 }
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index d409495876f1..739769551e33 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -56,7 +56,6 @@
 #include <xen/events.h>
 #include <xen/page.h>
 
-#include <xen/platform_pci.h>
 #include <xen/hvm.h>
 
 #include "xenbus_comms.h"
@@ -64,22 +63,15 @@
 
 
 int xen_store_evtchn;
-EXPORT_SYMBOL(xen_store_evtchn);
+EXPORT_SYMBOL_GPL(xen_store_evtchn);
 
 struct xenstore_domain_interface *xen_store_interface;
+EXPORT_SYMBOL_GPL(xen_store_interface);
+
 static unsigned long xen_store_mfn;
 
 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
 
-static void wait_for_devices(struct xenbus_driver *xendrv);
-
-static int xenbus_probe_frontend(const char *type, const char *name);
-
-static void xenbus_dev_shutdown(struct device *_dev);
-
-static int xenbus_dev_suspend(struct device *dev, pm_message_t state);
-static int xenbus_dev_resume(struct device *dev);
-
 /* If something in array of ids matches this device, return it. */
 static const struct xenbus_device_id *
 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
@@ -100,34 +92,7 @@ int xenbus_match(struct device *_dev, struct device_driver *_drv)
 
         return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
 }
-
-static int xenbus_uevent(struct device *_dev, struct kobj_uevent_env *env)
-{
-        struct xenbus_device *dev = to_xenbus_device(_dev);
-
-        if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
-                return -ENOMEM;
-
-        return 0;
-}
-
-/* device/<type>/<id> => <type>-<id> */
-static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
-{
-        nodename = strchr(nodename, '/');
-        if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
-                printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
-                return -EINVAL;
-        }
-
-        strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
-        if (!strchr(bus_id, '/')) {
-                printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
-                return -EINVAL;
-        }
-        *strchr(bus_id, '/') = '-';
-        return 0;
-}
+EXPORT_SYMBOL_GPL(xenbus_match);
 
 
 static void free_otherend_details(struct xenbus_device *dev)
@@ -147,7 +112,30 @@ static void free_otherend_watch(struct xenbus_device *dev)
 }
 
 
-int read_otherend_details(struct xenbus_device *xendev,
+static int talk_to_otherend(struct xenbus_device *dev)
+{
+        struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
+
+        free_otherend_watch(dev);
+        free_otherend_details(dev);
+
+        return drv->read_otherend_details(dev);
+}
+
+
+
+static int watch_otherend(struct xenbus_device *dev)
+{
+        struct xen_bus_type *bus =
+                container_of(dev->dev.bus, struct xen_bus_type, bus);
+
+        return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
+                                    bus->otherend_changed,
+                                    "%s/%s", dev->otherend, "state");
+}
+
+
+int xenbus_read_otherend_details(struct xenbus_device *xendev,
                                  char *id_node, char *path_node)
 {
         int err = xenbus_gather(XBT_NIL, xendev->nodename,
@@ -172,39 +160,11 @@ int read_otherend_details(struct xenbus_device *xendev,
 
         return 0;
 }
+EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
 
-
-static int read_backend_details(struct xenbus_device *xendev)
-{
-        return read_otherend_details(xendev, "backend-id", "backend");
-}
-
-static struct device_attribute xenbus_dev_attrs[] = {
-        __ATTR_NULL
-};
-
-/* Bus type for frontend drivers. */
-static struct xen_bus_type xenbus_frontend = {
-        .root = "device",
-        .levels = 2,            /* device/type/<id> */
-        .get_bus_id = frontend_bus_id,
-        .probe = xenbus_probe_frontend,
-        .bus = {
-                .name      = "xen",
-                .match     = xenbus_match,
-                .uevent    = xenbus_uevent,
-                .probe     = xenbus_dev_probe,
-                .remove    = xenbus_dev_remove,
-                .shutdown  = xenbus_dev_shutdown,
-                .dev_attrs = xenbus_dev_attrs,
-
-                .suspend   = xenbus_dev_suspend,
-                .resume    = xenbus_dev_resume,
-        },
-};
-
-static void otherend_changed(struct xenbus_watch *watch,
-                             const char **vec, unsigned int len)
+void xenbus_otherend_changed(struct xenbus_watch *watch,
+                             const char **vec, unsigned int len,
+                             int ignore_on_shutdown)
 {
         struct xenbus_device *dev =
                 container_of(watch, struct xenbus_device, otherend_watch);
@@ -232,11 +192,7 @@ static void otherend_changed(struct xenbus_watch *watch,
          * work that can fail e.g., when the rootfs is gone.
          */
         if (system_state > SYSTEM_RUNNING) {
-                struct xen_bus_type *bus = bus;
-                bus = container_of(dev->dev.bus, struct xen_bus_type, bus);
-                /* If we're frontend, drive the state machine to Closed. */
-                /* This should cause the backend to release our resources. */
-                if ((bus == &xenbus_frontend) && (state == XenbusStateClosing))
+                if (ignore_on_shutdown && (state == XenbusStateClosing))
                         xenbus_frontend_closed(dev);
                 return;
         }
@@ -244,25 +200,7 @@ static void otherend_changed(struct xenbus_watch *watch,
         if (drv->otherend_changed)
                 drv->otherend_changed(dev, state);
 }
-
-
-static int talk_to_otherend(struct xenbus_device *dev)
-{
-        struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
-
-        free_otherend_watch(dev);
-        free_otherend_details(dev);
-
-        return drv->read_otherend_details(dev);
-}
-
-
-static int watch_otherend(struct xenbus_device *dev)
-{
-        return xenbus_watch_pathfmt(dev, &dev->otherend_watch, otherend_changed,
-                                    "%s/%s", dev->otherend, "state");
-}
-
+EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
 
 int xenbus_dev_probe(struct device *_dev)
 {
@@ -306,8 +244,9 @@ int xenbus_dev_probe(struct device *_dev)
 fail:
         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
         xenbus_switch_state(dev, XenbusStateClosed);
-        return -ENODEV;
+        return err;
 }
+EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 
 int xenbus_dev_remove(struct device *_dev)
 {
@@ -325,8 +264,9 @@ int xenbus_dev_remove(struct device *_dev)
         xenbus_switch_state(dev, XenbusStateClosed);
         return 0;
 }
+EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 
-static void xenbus_dev_shutdown(struct device *_dev)
+void xenbus_dev_shutdown(struct device *_dev)
 {
         struct xenbus_device *dev = to_xenbus_device(_dev);
         unsigned long timeout = 5*HZ;
@@ -347,6 +287,7 @@ static void xenbus_dev_shutdown(struct device *_dev)
  out:
         put_device(&dev->dev);
 }
+EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 
 int xenbus_register_driver_common(struct xenbus_driver *drv,
                                   struct xen_bus_type *bus,
@@ -360,25 +301,7 @@ int xenbus_register_driver_common(struct xenbus_driver *drv,
 
         return driver_register(&drv->driver);
 }
-
-int __xenbus_register_frontend(struct xenbus_driver *drv,
-                               struct module *owner, const char *mod_name)
-{
-        int ret;
-
-        drv->read_otherend_details = read_backend_details;
-
-        ret = xenbus_register_driver_common(drv, &xenbus_frontend,
-                                            owner, mod_name);
-        if (ret)
-                return ret;
-
-        /* If this driver is loaded as a module wait for devices to attach. */
-        wait_for_devices(drv);
-
-        return 0;
-}
-EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
+EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 
 void xenbus_unregister_driver(struct xenbus_driver *drv)
 {
@@ -549,24 +472,7 @@ fail:
         kfree(xendev);
         return err;
 }
-
-/* device/<typename>/<name> */
-static int xenbus_probe_frontend(const char *type, const char *name)
-{
-        char *nodename;
-        int err;
-
-        nodename = kasprintf(GFP_KERNEL, "%s/%s/%s",
-                             xenbus_frontend.root, type, name);
-        if (!nodename)
-                return -ENOMEM;
-
-        DPRINTK("%s", nodename);
-
-        err = xenbus_probe_node(&xenbus_frontend, type, nodename);
-        kfree(nodename);
-        return err;
-}
+EXPORT_SYMBOL_GPL(xenbus_probe_node);
 
 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 {
@@ -580,10 +486,11 @@ static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
                 return PTR_ERR(dir);
 
         for (i = 0; i < dir_n; i++) {
-                err = bus->probe(type, dir[i]);
+                err = bus->probe(bus, type, dir[i]);
                 if (err)
                         break;
         }
+
         kfree(dir);
         return err;
 }
@@ -603,9 +510,11 @@ int xenbus_probe_devices(struct xen_bus_type *bus)
                 if (err)
                         break;
         }
+
         kfree(dir);
         return err;
 }
+EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 
 static unsigned int char_count(const char *str, char c)
 {
@@ -668,54 +577,39 @@ void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 }
 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 
-static void frontend_changed(struct xenbus_watch *watch,
-                             const char **vec, unsigned int len)
-{
-        DPRINTK("");
-
-        xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
-}
-
-/* We watch for devices appearing and vanishing. */
-static struct xenbus_watch fe_watch = {
-        .node = "device",
-        .callback = frontend_changed,
-};
-
-static int xenbus_dev_suspend(struct device *dev, pm_message_t state)
+int xenbus_dev_suspend(struct device *dev)
 {
         int err = 0;
         struct xenbus_driver *drv;
-        struct xenbus_device *xdev;
+        struct xenbus_device *xdev
+                = container_of(dev, struct xenbus_device, dev);
 
-        DPRINTK("");
+        DPRINTK("%s", xdev->nodename);
 
         if (dev->driver == NULL)
                 return 0;
         drv = to_xenbus_driver(dev->driver);
-        xdev = container_of(dev, struct xenbus_device, dev);
         if (drv->suspend)
-                err = drv->suspend(xdev, state);
+                err = drv->suspend(xdev);
         if (err)
                 printk(KERN_WARNING
                        "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
         return 0;
 }
+EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 
-static int xenbus_dev_resume(struct device *dev)
+int xenbus_dev_resume(struct device *dev)
 {
         int err;
         struct xenbus_driver *drv;
-        struct xenbus_device *xdev;
+        struct xenbus_device *xdev
+                = container_of(dev, struct xenbus_device, dev);
 
-        DPRINTK("");
+        DPRINTK("%s", xdev->nodename);
 
         if (dev->driver == NULL)
                 return 0;
-
         drv = to_xenbus_driver(dev->driver);
-        xdev = container_of(dev, struct xenbus_device, dev);
-
         err = talk_to_otherend(xdev);
         if (err) {
                 printk(KERN_WARNING
@@ -746,6 +640,15 @@ static int xenbus_dev_resume(struct device *dev)
 
         return 0;
 }
+EXPORT_SYMBOL_GPL(xenbus_dev_resume);
+
+int xenbus_dev_cancel(struct device *dev)
+{
+        /* Do nothing */
+        DPRINTK("cancel");
+        return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 
 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 int xenstored_ready = 0;
@@ -774,11 +677,6 @@ void xenbus_probe(struct work_struct *unused)
 {
         xenstored_ready = 1;
 
-        /* Enumerate devices in xenstore and watch for changes. */
-        xenbus_probe_devices(&xenbus_frontend);
-        register_xenbus_watch(&fe_watch);
-        xenbus_backend_probe_and_watch();
-
         /* Notify others that xenstore is up */
         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 }
@@ -801,27 +699,43 @@ device_initcall(xenbus_probe_initcall);
 static int __init xenbus_init(void)
 {
         int err = 0;
+        unsigned long page = 0;
 
         DPRINTK("");
 
         err = -ENODEV;
         if (!xen_domain())
-                goto out_error;
-
-        /* Register ourselves with the kernel bus subsystem */
-        err = bus_register(&xenbus_frontend.bus);
-        if (err)
-                goto out_error;
-
-        err = xenbus_backend_bus_register();
-        if (err)
-                goto out_unreg_front;
+                return err;
 
         /*
          * Domain0 doesn't have a store_evtchn or store_mfn yet.
          */
         if (xen_initial_domain()) {
-                /* dom0 not yet supported */
+                struct evtchn_alloc_unbound alloc_unbound;
+
+                /* Allocate Xenstore page */
+                page = get_zeroed_page(GFP_KERNEL);
+                if (!page)
+                        goto out_error;
+
+                xen_store_mfn = xen_start_info->store_mfn =
+                        pfn_to_mfn(virt_to_phys((void *)page) >>
+                                   PAGE_SHIFT);
+
+                /* Next allocate a local port which xenstored can bind to */
+                alloc_unbound.dom        = DOMID_SELF;
+                alloc_unbound.remote_dom = 0;
+
+                err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
+                                                  &alloc_unbound);
+                if (err == -ENOSYS)
+                        goto out_error;
+
+                BUG_ON(err);
+                xen_store_evtchn = xen_start_info->store_evtchn =
+                        alloc_unbound.port;
+
+                xen_store_interface = mfn_to_virt(xen_store_mfn);
         } else {
                 if (xen_hvm_domain()) {
                         uint64_t v = 0;
@@ -847,7 +761,7 @@ static int __init xenbus_init(void)
         if (err) {
                 printk(KERN_WARNING
                        "XENBUS: Error initializing xenstore comms: %i\n", err);
-                goto out_unreg_back;
+                goto out_error;
         }
 
 #ifdef CONFIG_XEN_COMPAT_XENFS
@@ -860,131 +774,13 @@ static int __init xenbus_init(void)
 
         return 0;
 
-  out_unreg_back:
-        xenbus_backend_bus_unregister();
-
-  out_unreg_front:
-        bus_unregister(&xenbus_frontend.bus);
-
   out_error:
+        if (page != 0)
+                free_page(page);
+
         return err;
 }
 
 postcore_initcall(xenbus_init);
 
 MODULE_LICENSE("GPL");
-
-static int is_device_connecting(struct device *dev, void *data)
-{
-        struct xenbus_device *xendev = to_xenbus_device(dev);
-        struct device_driver *drv = data;
-        struct xenbus_driver *xendrv;
-
-        /*
-         * A device with no driver will never connect. We care only about
-         * devices which should currently be in the process of connecting.
-         */
-        if (!dev->driver)
-                return 0;
-
-        /* Is this search limited to a particular driver? */
-        if (drv && (dev->driver != drv))
-                return 0;
-
-        xendrv = to_xenbus_driver(dev->driver);
-        return (xendev->state < XenbusStateConnected ||
-                (xendev->state == XenbusStateConnected &&
-                 xendrv->is_ready && !xendrv->is_ready(xendev)));
-}
-
-static int exists_connecting_device(struct device_driver *drv)
-{
-        return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
-                                is_device_connecting);
-}
-
-static int print_device_status(struct device *dev, void *data)
-{
-        struct xenbus_device *xendev = to_xenbus_device(dev);
-        struct device_driver *drv = data;
-
-        /* Is this operation limited to a particular driver? */
-        if (drv && (dev->driver != drv))
-                return 0;
-
-        if (!dev->driver) {
-                /* Information only: is this too noisy? */
-                printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
-                       xendev->nodename);
-        } else if (xendev->state < XenbusStateConnected) {
-                enum xenbus_state rstate = XenbusStateUnknown;
-                if (xendev->otherend)
-                        rstate = xenbus_read_driver_state(xendev->otherend);
-                printk(KERN_WARNING "XENBUS: Timeout connecting "
-                       "to device: %s (local state %d, remote state %d)\n",
-                       xendev->nodename, xendev->state, rstate);
-        }
-
-        return 0;
-}
-
-/* We only wait for device setup after most initcalls have run. */
-static int ready_to_wait_for_devices;
-
-/*
- * On a 5-minute timeout, wait for all devices currently configured.  We need
- * to do this to guarantee that the filesystems and / or network devices
- * needed for boot are available, before we can allow the boot to proceed.
- *
- * This needs to be on a late_initcall, to happen after the frontend device
- * drivers have been initialised, but before the root fs is mounted.
- *
- * A possible improvement here would be to have the tools add a per-device
- * flag to the store entry, indicating whether it is needed at boot time.
- * This would allow people who knew what they were doing to accelerate their
- * boot slightly, but of course needs tools or manual intervention to set up
- * those flags correctly.
- */
-static void wait_for_devices(struct xenbus_driver *xendrv)
-{
-        unsigned long start = jiffies;
-        struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
-        unsigned int seconds_waited = 0;
-
-        if (!ready_to_wait_for_devices || !xen_domain())
-                return;
-
-        while (exists_connecting_device(drv)) {
-                if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
-                        if (!seconds_waited)
-                                printk(KERN_WARNING "XENBUS: Waiting for "
-                                       "devices to initialise: ");
-                        seconds_waited += 5;
-                        printk("%us...", 300 - seconds_waited);
-                        if (seconds_waited == 300)
-                                break;
-                }
-
-                schedule_timeout_interruptible(HZ/10);
-        }
-
-        if (seconds_waited)
-                printk("\n");
-
-        bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
-                         print_device_status);
-}
-
-#ifndef MODULE
-static int __init boot_wait_for_devices(void)
-{
-        if (xen_hvm_domain() && !xen_platform_pci_unplug)
-                return -ENODEV;
-
-        ready_to_wait_for_devices = 1;
-        wait_for_devices(NULL);
-        return 0;
-}
-
-late_initcall(boot_wait_for_devices);
-#endif
diff --git a/drivers/xen/xenbus/xenbus_probe.h b/drivers/xen/xenbus/xenbus_probe.h
index 6c5e3185a6a2..888b9900ca08 100644
--- a/drivers/xen/xenbus/xenbus_probe.h
+++ b/drivers/xen/xenbus/xenbus_probe.h
@@ -36,26 +36,15 @@
 
 #define XEN_BUS_ID_SIZE                 20
 
-#ifdef CONFIG_XEN_BACKEND
-extern void xenbus_backend_suspend(int (*fn)(struct device *, void *));
-extern void xenbus_backend_resume(int (*fn)(struct device *, void *));
-extern void xenbus_backend_probe_and_watch(void);
-extern int xenbus_backend_bus_register(void);
-extern void xenbus_backend_bus_unregister(void);
-#else
-static inline void xenbus_backend_suspend(int (*fn)(struct device *, void *)) {}
-static inline void xenbus_backend_resume(int (*fn)(struct device *, void *)) {}
-static inline void xenbus_backend_probe_and_watch(void) {}
-static inline int xenbus_backend_bus_register(void) { return 0; }
-static inline void xenbus_backend_bus_unregister(void) {}
-#endif
-
 struct xen_bus_type
 {
         char *root;
         unsigned int levels;
         int (*get_bus_id)(char bus_id[XEN_BUS_ID_SIZE], const char *nodename);
-        int (*probe)(const char *type, const char *dir);
+        int (*probe)(struct xen_bus_type *bus, const char *type,
+                     const char *dir);
+        void (*otherend_changed)(struct xenbus_watch *watch, const char **vec,
+                                 unsigned int len);
         struct bus_type bus;
 };
 
@@ -73,4 +62,17 @@ extern int xenbus_probe_devices(struct xen_bus_type *bus);
 
 extern void xenbus_dev_changed(const char *node, struct xen_bus_type *bus);
 
+extern void xenbus_dev_shutdown(struct device *_dev);
+
+extern int xenbus_dev_suspend(struct device *dev);
+extern int xenbus_dev_resume(struct device *dev);
+extern int xenbus_dev_cancel(struct device *dev);
+
+extern void xenbus_otherend_changed(struct xenbus_watch *watch,
+                                    const char **vec, unsigned int len,
+                                    int ignore_on_shutdown);
+
+extern int xenbus_read_otherend_details(struct xenbus_device *xendev,
+                                        char *id_node, char *path_node);
+
 #endif
diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c
new file mode 100644
index 000000000000..6cf467bf63ec
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe_backend.c
@@ -0,0 +1,276 @@
+/******************************************************************************
+ * Talks to Xen Store to figure out what devices we have (backend half).
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * Copyright (C) 2005 Mike Wray, Hewlett-Packard
+ * Copyright (C) 2005, 2006 XenSource Ltd
+ * Copyright (C) 2007 Solarflare Communications, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#define DPRINTK(fmt, args...)                           \
+        pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
+                 __func__, __LINE__, ##args)
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/notifier.h>
+
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/hypervisor.h>
+#include <xen/xenbus.h>
+#include <xen/features.h>
+
+#include "xenbus_comms.h"
+#include "xenbus_probe.h"
+
+/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
+static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
+{
+        int domid, err;
+        const char *devid, *type, *frontend;
+        unsigned int typelen;
+
+        type = strchr(nodename, '/');
+        if (!type)
+                return -EINVAL;
+        type++;
+        typelen = strcspn(type, "/");
+        if (!typelen || type[typelen] != '/')
+                return -EINVAL;
+
+        devid = strrchr(nodename, '/') + 1;
+
+        err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
+                            "frontend", NULL, &frontend,
+                            NULL);
+        if (err)
+                return err;
+        if (strlen(frontend) == 0)
+                err = -ERANGE;
+        if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
+                err = -ENOENT;
+        kfree(frontend);
+
+        if (err)
+                return err;
+
+        if (snprintf(bus_id, XEN_BUS_ID_SIZE, "%.*s-%i-%s",
+                     typelen, type, domid, devid) >= XEN_BUS_ID_SIZE)
+                return -ENOSPC;
+        return 0;
+}
+
+static int xenbus_uevent_backend(struct device *dev,
+                                 struct kobj_uevent_env *env)
+{
+        struct xenbus_device *xdev;
+        struct xenbus_driver *drv;
+        struct xen_bus_type *bus;
+
+        DPRINTK("");
+
+        if (dev == NULL)
+                return -ENODEV;
+
+        xdev = to_xenbus_device(dev);
+        bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
+        if (xdev == NULL)
+                return -ENODEV;
+
+        /* stuff we want to pass to /sbin/hotplug */
+        if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype))
+                return -ENOMEM;
+
+        if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename))
+                return -ENOMEM;
+
+        if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root))
+                return -ENOMEM;
+
+        if (dev->driver) {
+                drv = to_xenbus_driver(dev->driver);
+                if (drv && drv->uevent)
+                        return drv->uevent(xdev, env);
+        }
+
+        return 0;
+}
+
+/* backend/<typename>/<frontend-uuid>/<name> */
+static int xenbus_probe_backend_unit(struct xen_bus_type *bus,
+                                     const char *dir,
+                                     const char *type,
+                                     const char *name)
+{
+        char *nodename;
+        int err;
+
+        nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
+        if (!nodename)
+                return -ENOMEM;
+
+        DPRINTK("%s\n", nodename);
+
+        err = xenbus_probe_node(bus, type, nodename);
+        kfree(nodename);
+        return err;
+}
+
+/* backend/<typename>/<frontend-domid> */
+static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
+                                const char *domid)
+{
+        char *nodename;
+        int err = 0;
+        char **dir;
+        unsigned int i, dir_n = 0;
+
+        DPRINTK("");
+
+        nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid);
+        if (!nodename)
+                return -ENOMEM;
+
+        dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
+        if (IS_ERR(dir)) {
+                kfree(nodename);
+                return PTR_ERR(dir);
+        }
+
+        for (i = 0; i < dir_n; i++) {
+                err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]);
+                if (err)
+                        break;
+        }
+        kfree(dir);
+        kfree(nodename);
+        return err;
+}
+
+static void frontend_changed(struct xenbus_watch *watch,
+                            const char **vec, unsigned int len)
+{
+        xenbus_otherend_changed(watch, vec, len, 0);
+}
+
+static struct device_attribute xenbus_backend_dev_attrs[] = {
+        __ATTR_NULL
+};
+
+static struct xen_bus_type xenbus_backend = {
+        .root = "backend",
+        .levels = 3,            /* backend/type/<frontend>/<id> */
+        .get_bus_id = backend_bus_id,
+        .probe = xenbus_probe_backend,
+        .otherend_changed = frontend_changed,
+        .bus = {
+                .name           = "xen-backend",
+                .match          = xenbus_match,
+                .uevent         = xenbus_uevent_backend,
+                .probe          = xenbus_dev_probe,
+                .remove         = xenbus_dev_remove,
+                .shutdown       = xenbus_dev_shutdown,
+                .dev_attrs      = xenbus_backend_dev_attrs,
+        },
+};
+
+static void backend_changed(struct xenbus_watch *watch,
+                            const char **vec, unsigned int len)
+{
+        DPRINTK("");
+
+        xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
+}
+
+static struct xenbus_watch be_watch = {
+        .node = "backend",
+        .callback = backend_changed,
+};
+
+static int read_frontend_details(struct xenbus_device *xendev)
+{
+        return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
+}
+
+int xenbus_dev_is_online(struct xenbus_device *dev)
+{
+        int rc, val;
+
+        rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val);
+        if (rc != 1)
+                val = 0; /* no online node present */
+
+        return val;
+}
+EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
+
+int __xenbus_register_backend(struct xenbus_driver *drv,
+                              struct module *owner, const char *mod_name)
+{
+        drv->read_otherend_details = read_frontend_details;
+
+        return xenbus_register_driver_common(drv, &xenbus_backend,
+                                             owner, mod_name);
+}
+EXPORT_SYMBOL_GPL(__xenbus_register_backend);
+
+static int backend_probe_and_watch(struct notifier_block *notifier,
+                                   unsigned long event,
+                                   void *data)
+{
+        /* Enumerate devices in xenstore and watch for changes. */
+        xenbus_probe_devices(&xenbus_backend);
+        register_xenbus_watch(&be_watch);
+
+        return NOTIFY_DONE;
+}
+
+static int __init xenbus_probe_backend_init(void)
+{
+        static struct notifier_block xenstore_notifier = {
+                .notifier_call = backend_probe_and_watch
+        };
+        int err;
+
+        DPRINTK("");
+
+        /* Register ourselves with the kernel bus subsystem */
+        err = bus_register(&xenbus_backend.bus);
+        if (err)
+                return err;
+
+        register_xenstore_notifier(&xenstore_notifier);
+
+        return 0;
+}
+subsys_initcall(xenbus_probe_backend_init);
diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
new file mode 100644
index 000000000000..b6a2690c9d49
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
@@ -0,0 +1,301 @@
+#define DPRINTK(fmt, args...)                           \
+        pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
+                 __func__, __LINE__, ##args)
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/proc_fs.h>
+#include <linux/notifier.h>
+#include <linux/kthread.h>
+#include <linux/mutex.h>
+#include <linux/io.h>
+
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/xenbus.h>
+#include <xen/events.h>
+#include <xen/page.h>
+
+#include <xen/platform_pci.h>
+
+#include "xenbus_comms.h"
+#include "xenbus_probe.h"
+
+
+/* device/<type>/<id> => <type>-<id> */
+static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
+{
+        nodename = strchr(nodename, '/');
+        if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
+                printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
+                return -EINVAL;
+        }
+
+        strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
+        if (!strchr(bus_id, '/')) {
+                printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
+                return -EINVAL;
+        }
+        *strchr(bus_id, '/') = '-';
+        return 0;
+}
+
+/* device/<typename>/<name> */
+static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
+                                 const char *name)
+{
+        char *nodename;
+        int err;
+
+        nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
+        if (!nodename)
+                return -ENOMEM;
+
+        DPRINTK("%s", nodename);
+
+        err = xenbus_probe_node(bus, type, nodename);
+        kfree(nodename);
+        return err;
+}
+
+static int xenbus_uevent_frontend(struct device *_dev,
+                                  struct kobj_uevent_env *env)
+{
+        struct xenbus_device *dev = to_xenbus_device(_dev);
+
+        if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
+                return -ENOMEM;
+
+        return 0;
+}
+
+
+static void backend_changed(struct xenbus_watch *watch,
+                            const char **vec, unsigned int len)
+{
+        xenbus_otherend_changed(watch, vec, len, 1);
+}
+
+static struct device_attribute xenbus_frontend_dev_attrs[] = {
+        __ATTR_NULL
+};
+
+static const struct dev_pm_ops xenbus_pm_ops = {
+        .suspend        = xenbus_dev_suspend,
+        .resume         = xenbus_dev_resume,
+        .freeze         = xenbus_dev_suspend,
+        .thaw           = xenbus_dev_cancel,
+        .restore        = xenbus_dev_resume,
+};
+
+static struct xen_bus_type xenbus_frontend = {
+        .root = "device",
+        .levels = 2,            /* device/type/<id> */
+        .get_bus_id = frontend_bus_id,
+        .probe = xenbus_probe_frontend,
+        .otherend_changed = backend_changed,
+        .bus = {
+                .name           = "xen",
+                .match          = xenbus_match,
+                .uevent         = xenbus_uevent_frontend,
+                .probe          = xenbus_dev_probe,
+                .remove         = xenbus_dev_remove,
+                .shutdown       = xenbus_dev_shutdown,
+                .dev_attrs      = xenbus_frontend_dev_attrs,
+
+                .pm             = &xenbus_pm_ops,
+        },
+};
+
+static void frontend_changed(struct xenbus_watch *watch,
+                             const char **vec, unsigned int len)
+{
+        DPRINTK("");
+
+        xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
+}
+
+
+/* We watch for devices appearing and vanishing. */
+static struct xenbus_watch fe_watch = {
+        .node = "device",
+        .callback = frontend_changed,
+};
+
+static int read_backend_details(struct xenbus_device *xendev)
+{
+        return xenbus_read_otherend_details(xendev, "backend-id", "backend");
+}
+
+static int is_device_connecting(struct device *dev, void *data)
+{
+        struct xenbus_device *xendev = to_xenbus_device(dev);
+        struct device_driver *drv = data;
+        struct xenbus_driver *xendrv;
+
+        /*
+         * A device with no driver will never connect. We care only about
+         * devices which should currently be in the process of connecting.
+         */
+        if (!dev->driver)
+                return 0;
+
+        /* Is this search limited to a particular driver? */
+        if (drv && (dev->driver != drv))
+                return 0;
+
+        xendrv = to_xenbus_driver(dev->driver);
+        return (xendev->state < XenbusStateConnected ||
+                (xendev->state == XenbusStateConnected &&
+                 xendrv->is_ready && !xendrv->is_ready(xendev)));
+}
+
+static int exists_connecting_device(struct device_driver *drv)
+{
+        return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
+                                is_device_connecting);
+}
+
+static int print_device_status(struct device *dev, void *data)
+{
+        struct xenbus_device *xendev = to_xenbus_device(dev);
+        struct device_driver *drv = data;
+
+        /* Is this operation limited to a particular driver? */
+        if (drv && (dev->driver != drv))
+                return 0;
+
+        if (!dev->driver) {
+                /* Information only: is this too noisy? */
+                printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
+                       xendev->nodename);
+        } else if (xendev->state < XenbusStateConnected) {
+                enum xenbus_state rstate = XenbusStateUnknown;
+                if (xendev->otherend)
+                        rstate = xenbus_read_driver_state(xendev->otherend);
+                printk(KERN_WARNING "XENBUS: Timeout connecting "
+                       "to device: %s (local state %d, remote state %d)\n",
+                       xendev->nodename, xendev->state, rstate);
+        }
+
+        return 0;
+}
+
+/* We only wait for device setup after most initcalls have run. */
+static int ready_to_wait_for_devices;
+
+/*
+ * On a 5-minute timeout, wait for all devices currently configured.  We need
+ * to do this to guarantee that the filesystems and / or network devices
+ * needed for boot are available, before we can allow the boot to proceed.
+ *
+ * This needs to be on a late_initcall, to happen after the frontend device
+ * drivers have been initialised, but before the root fs is mounted.
+ *
+ * A possible improvement here would be to have the tools add a per-device
+ * flag to the store entry, indicating whether it is needed at boot time.
+ * This would allow people who knew what they were doing to accelerate their
+ * boot slightly, but of course needs tools or manual intervention to set up
+ * those flags correctly.
+ */
+static void wait_for_devices(struct xenbus_driver *xendrv)
+{
+        unsigned long start = jiffies;
+        struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
+        unsigned int seconds_waited = 0;
+
+        if (!ready_to_wait_for_devices || !xen_domain())
+                return;
+
+        while (exists_connecting_device(drv)) {
+                if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
+                        if (!seconds_waited)
+                                printk(KERN_WARNING "XENBUS: Waiting for "
+                                       "devices to initialise: ");
+                        seconds_waited += 5;
+                        printk("%us...", 300 - seconds_waited);
+                        if (seconds_waited == 300)
+                                break;
+                }
+
+                schedule_timeout_interruptible(HZ/10);
+        }
+
+        if (seconds_waited)
+                printk("\n");
+
+        bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
+                         print_device_status);
+}
+
+int __xenbus_register_frontend(struct xenbus_driver *drv,
+                               struct module *owner, const char *mod_name)
+{
+        int ret;
+
+        drv->read_otherend_details = read_backend_details;
+
+        ret = xenbus_register_driver_common(drv, &xenbus_frontend,
+                                            owner, mod_name);
+        if (ret)
+                return ret;
+
+        /* If this driver is loaded as a module wait for devices to attach. */
+        wait_for_devices(drv);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
+
+static int frontend_probe_and_watch(struct notifier_block *notifier,
+                                   unsigned long event,
+                                   void *data)
+{
+        /* Enumerate devices in xenstore and watch for changes. */
+        xenbus_probe_devices(&xenbus_frontend);
+        register_xenbus_watch(&fe_watch);
+
+        return NOTIFY_DONE;
+}
+
+
+static int __init xenbus_probe_frontend_init(void)
+{
+        static struct notifier_block xenstore_notifier = {
+                .notifier_call = frontend_probe_and_watch
+        };
+        int err;
+
+        DPRINTK("");
+
+        /* Register ourselves with the kernel bus subsystem */
+        err = bus_register(&xenbus_frontend.bus);
+        if (err)
+                return err;
+
+        register_xenstore_notifier(&xenstore_notifier);
+
+        return 0;
+}
+subsys_initcall(xenbus_probe_frontend_init);
+
+#ifndef MODULE
+static int __init boot_wait_for_devices(void)
+{
+        if (xen_hvm_domain() && !xen_platform_pci_unplug)
+                return -ENODEV;
+
+        ready_to_wait_for_devices = 1;
+        wait_for_devices(NULL);
+        return 0;
+}
+
+late_initcall(boot_wait_for_devices);
+#endif
+
+MODULE_LICENSE("GPL");