xen: add the Xenbus sysfs and virtual device hotplug driver
This communicates with the machine control software via a registry
residing in a controlling virtual machine. This allows dynamic
creation, destruction and modification of virtual device
configurations (network devices, block devices and CPUS, to name some
examples).
[ Greg, would you mind giving this a review? Thanks -J ]
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Greg KH <greg@kroah.com>
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
new file mode 100644
index 0000000..0b769f7
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -0,0 +1,935 @@
+/******************************************************************************
+ * Talks to Xen Store to figure out what devices we have.
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * Copyright (C) 2005 Mike Wray, Hewlett-Packard
+ * Copyright (C) 2005, 2006 XenSource Ltd
+ *
+ * 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 <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 "xenbus_comms.h"
+#include "xenbus_probe.h"
+
+int xen_store_evtchn;
+struct xenstore_domain_interface *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);
+
+/* 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)
+{
+ for (; *arr->devicetype != '\0'; arr++) {
+ if (!strcmp(arr->devicetype, dev->devicetype))
+ return arr;
+ }
+ return NULL;
+}
+
+int xenbus_match(struct device *_dev, struct device_driver *_drv)
+{
+ struct xenbus_driver *drv = to_xenbus_driver(_drv);
+
+ if (!drv->ids)
+ return 0;
+
+ return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
+}
+
+/* device/<type>/<id> => <type>-<id> */
+static int frontend_bus_id(char bus_id[BUS_ID_SIZE], const char *nodename)
+{
+ nodename = strchr(nodename, '/');
+ if (!nodename || strlen(nodename + 1) >= BUS_ID_SIZE) {
+ printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
+ return -EINVAL;
+ }
+
+ strlcpy(bus_id, nodename + 1, 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;
+}
+
+
+static void free_otherend_details(struct xenbus_device *dev)
+{
+ kfree(dev->otherend);
+ dev->otherend = NULL;
+}
+
+
+static void free_otherend_watch(struct xenbus_device *dev)
+{
+ if (dev->otherend_watch.node) {
+ unregister_xenbus_watch(&dev->otherend_watch);
+ kfree(dev->otherend_watch.node);
+ dev->otherend_watch.node = NULL;
+ }
+}
+
+
+int read_otherend_details(struct xenbus_device *xendev,
+ char *id_node, char *path_node)
+{
+ int err = xenbus_gather(XBT_NIL, xendev->nodename,
+ id_node, "%i", &xendev->otherend_id,
+ path_node, NULL, &xendev->otherend,
+ NULL);
+ if (err) {
+ xenbus_dev_fatal(xendev, err,
+ "reading other end details from %s",
+ xendev->nodename);
+ return err;
+ }
+ if (strlen(xendev->otherend) == 0 ||
+ !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
+ xenbus_dev_fatal(xendev, -ENOENT,
+ "unable to read other end from %s. "
+ "missing or inaccessible.",
+ xendev->nodename);
+ free_otherend_details(xendev);
+ return -ENOENT;
+ }
+
+ return 0;
+}
+
+
+static int read_backend_details(struct xenbus_device *xendev)
+{
+ return read_otherend_details(xendev, "backend-id", "backend");
+}
+
+
+/* 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,
+ .probe = xenbus_dev_probe,
+ .remove = xenbus_dev_remove,
+ .shutdown = xenbus_dev_shutdown,
+ },
+};
+
+static void otherend_changed(struct xenbus_watch *watch,
+ const char **vec, unsigned int len)
+{
+ struct xenbus_device *dev =
+ container_of(watch, struct xenbus_device, otherend_watch);
+ struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
+ enum xenbus_state state;
+
+ /* Protect us against watches firing on old details when the otherend
+ details change, say immediately after a resume. */
+ if (!dev->otherend ||
+ strncmp(dev->otherend, vec[XS_WATCH_PATH],
+ strlen(dev->otherend))) {
+ dev_dbg(&dev->dev, "Ignoring watch at %s", vec[XS_WATCH_PATH]);
+ return;
+ }
+
+ state = xenbus_read_driver_state(dev->otherend);
+
+ dev_dbg(&dev->dev, "state is %d, (%s), %s, %s",
+ state, xenbus_strstate(state), dev->otherend_watch.node,
+ vec[XS_WATCH_PATH]);
+
+ /*
+ * Ignore xenbus transitions during shutdown. This prevents us doing
+ * 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))
+ xenbus_frontend_closed(dev);
+ return;
+ }
+
+ 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");
+}
+
+
+int xenbus_dev_probe(struct device *_dev)
+{
+ struct xenbus_device *dev = to_xenbus_device(_dev);
+ struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
+ const struct xenbus_device_id *id;
+ int err;
+
+ DPRINTK("%s", dev->nodename);
+
+ if (!drv->probe) {
+ err = -ENODEV;
+ goto fail;
+ }
+
+ id = match_device(drv->ids, dev);
+ if (!id) {
+ err = -ENODEV;
+ goto fail;
+ }
+
+ err = talk_to_otherend(dev);
+ if (err) {
+ dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
+ dev->nodename);
+ return err;
+ }
+
+ err = drv->probe(dev, id);
+ if (err)
+ goto fail;
+
+ err = watch_otherend(dev);
+ if (err) {
+ dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
+ dev->nodename);
+ return err;
+ }
+
+ return 0;
+fail:
+ xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
+ xenbus_switch_state(dev, XenbusStateClosed);
+ return -ENODEV;
+}
+
+int xenbus_dev_remove(struct device *_dev)
+{
+ struct xenbus_device *dev = to_xenbus_device(_dev);
+ struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
+
+ DPRINTK("%s", dev->nodename);
+
+ free_otherend_watch(dev);
+ free_otherend_details(dev);
+
+ if (drv->remove)
+ drv->remove(dev);
+
+ xenbus_switch_state(dev, XenbusStateClosed);
+ return 0;
+}
+
+static void xenbus_dev_shutdown(struct device *_dev)
+{
+ struct xenbus_device *dev = to_xenbus_device(_dev);
+ unsigned long timeout = 5*HZ;
+
+ DPRINTK("%s", dev->nodename);
+
+ get_device(&dev->dev);
+ if (dev->state != XenbusStateConnected) {
+ printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
+ dev->nodename, xenbus_strstate(dev->state));
+ goto out;
+ }
+ xenbus_switch_state(dev, XenbusStateClosing);
+ timeout = wait_for_completion_timeout(&dev->down, timeout);
+ if (!timeout)
+ printk(KERN_INFO "%s: %s timeout closing device\n",
+ __func__, dev->nodename);
+ out:
+ put_device(&dev->dev);
+}
+
+int xenbus_register_driver_common(struct xenbus_driver *drv,
+ struct xen_bus_type *bus,
+ struct module *owner,
+ const char *mod_name)
+{
+ drv->driver.name = drv->name;
+ drv->driver.bus = &bus->bus;
+ drv->driver.owner = owner;
+ drv->driver.mod_name = mod_name;
+
+ 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);
+
+void xenbus_unregister_driver(struct xenbus_driver *drv)
+{
+ driver_unregister(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
+
+struct xb_find_info
+{
+ struct xenbus_device *dev;
+ const char *nodename;
+};
+
+static int cmp_dev(struct device *dev, void *data)
+{
+ struct xenbus_device *xendev = to_xenbus_device(dev);
+ struct xb_find_info *info = data;
+
+ if (!strcmp(xendev->nodename, info->nodename)) {
+ info->dev = xendev;
+ get_device(dev);
+ return 1;
+ }
+ return 0;
+}
+
+struct xenbus_device *xenbus_device_find(const char *nodename,
+ struct bus_type *bus)
+{
+ struct xb_find_info info = { .dev = NULL, .nodename = nodename };
+
+ bus_for_each_dev(bus, NULL, &info, cmp_dev);
+ return info.dev;
+}
+
+static int cleanup_dev(struct device *dev, void *data)
+{
+ struct xenbus_device *xendev = to_xenbus_device(dev);
+ struct xb_find_info *info = data;
+ int len = strlen(info->nodename);
+
+ DPRINTK("%s", info->nodename);
+
+ /* Match the info->nodename path, or any subdirectory of that path. */
+ if (strncmp(xendev->nodename, info->nodename, len))
+ return 0;
+
+ /* If the node name is longer, ensure it really is a subdirectory. */
+ if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
+ return 0;
+
+ info->dev = xendev;
+ get_device(dev);
+ return 1;
+}
+
+static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
+{
+ struct xb_find_info info = { .nodename = path };
+
+ do {
+ info.dev = NULL;
+ bus_for_each_dev(bus, NULL, &info, cleanup_dev);
+ if (info.dev) {
+ device_unregister(&info.dev->dev);
+ put_device(&info.dev->dev);
+ }
+ } while (info.dev);
+}
+
+static void xenbus_dev_release(struct device *dev)
+{
+ if (dev)
+ kfree(to_xenbus_device(dev));
+}
+
+static ssize_t xendev_show_nodename(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
+}
+DEVICE_ATTR(nodename, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_nodename, NULL);
+
+static ssize_t xendev_show_devtype(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
+}
+DEVICE_ATTR(devtype, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_devtype, NULL);
+
+
+int xenbus_probe_node(struct xen_bus_type *bus,
+ const char *type,
+ const char *nodename)
+{
+ int err;
+ struct xenbus_device *xendev;
+ size_t stringlen;
+ char *tmpstring;
+
+ enum xenbus_state state = xenbus_read_driver_state(nodename);
+
+ if (state != XenbusStateInitialising) {
+ /* Device is not new, so ignore it. This can happen if a
+ device is going away after switching to Closed. */
+ return 0;
+ }
+
+ stringlen = strlen(nodename) + 1 + strlen(type) + 1;
+ xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
+ if (!xendev)
+ return -ENOMEM;
+
+ xendev->state = XenbusStateInitialising;
+
+ /* Copy the strings into the extra space. */
+
+ tmpstring = (char *)(xendev + 1);
+ strcpy(tmpstring, nodename);
+ xendev->nodename = tmpstring;
+
+ tmpstring += strlen(tmpstring) + 1;
+ strcpy(tmpstring, type);
+ xendev->devicetype = tmpstring;
+ init_completion(&xendev->down);
+
+ xendev->dev.bus = &bus->bus;
+ xendev->dev.release = xenbus_dev_release;
+
+ err = bus->get_bus_id(xendev->dev.bus_id, xendev->nodename);
+ if (err)
+ goto fail;
+
+ /* Register with generic device framework. */
+ err = device_register(&xendev->dev);
+ if (err)
+ goto fail;
+
+ err = device_create_file(&xendev->dev, &dev_attr_nodename);
+ if (err)
+ goto fail_unregister;
+
+ err = device_create_file(&xendev->dev, &dev_attr_devtype);
+ if (err)
+ goto fail_remove_file;
+
+ return 0;
+fail_remove_file:
+ device_remove_file(&xendev->dev, &dev_attr_nodename);
+fail_unregister:
+ device_unregister(&xendev->dev);
+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;
+}
+
+static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
+{
+ int err = 0;
+ char **dir;
+ unsigned int dir_n = 0;
+ int i;
+
+ dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
+ if (IS_ERR(dir))
+ return PTR_ERR(dir);
+
+ for (i = 0; i < dir_n; i++) {
+ err = bus->probe(type, dir[i]);
+ if (err)
+ break;
+ }
+ kfree(dir);
+ return err;
+}
+
+int xenbus_probe_devices(struct xen_bus_type *bus)
+{
+ int err = 0;
+ char **dir;
+ unsigned int i, dir_n;
+
+ dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
+ if (IS_ERR(dir))
+ return PTR_ERR(dir);
+
+ for (i = 0; i < dir_n; i++) {
+ err = xenbus_probe_device_type(bus, dir[i]);
+ if (err)
+ break;
+ }
+ kfree(dir);
+ return err;
+}
+
+static unsigned int char_count(const char *str, char c)
+{
+ unsigned int i, ret = 0;
+
+ for (i = 0; str[i]; i++)
+ if (str[i] == c)
+ ret++;
+ return ret;
+}
+
+static int strsep_len(const char *str, char c, unsigned int len)
+{
+ unsigned int i;
+
+ for (i = 0; str[i]; i++)
+ if (str[i] == c) {
+ if (len == 0)
+ return i;
+ len--;
+ }
+ return (len == 0) ? i : -ERANGE;
+}
+
+void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
+{
+ int exists, rootlen;
+ struct xenbus_device *dev;
+ char type[BUS_ID_SIZE];
+ const char *p, *root;
+
+ if (char_count(node, '/') < 2)
+ return;
+
+ exists = xenbus_exists(XBT_NIL, node, "");
+ if (!exists) {
+ xenbus_cleanup_devices(node, &bus->bus);
+ return;
+ }
+
+ /* backend/<type>/... or device/<type>/... */
+ p = strchr(node, '/') + 1;
+ snprintf(type, BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
+ type[BUS_ID_SIZE-1] = '\0';
+
+ rootlen = strsep_len(node, '/', bus->levels);
+ if (rootlen < 0)
+ return;
+ root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
+ if (!root)
+ return;
+
+ dev = xenbus_device_find(root, &bus->bus);
+ if (!dev)
+ xenbus_probe_node(bus, type, root);
+ else
+ put_device(&dev->dev);
+
+ kfree(root);
+}
+
+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 suspend_dev(struct device *dev, void *data)
+{
+ int err = 0;
+ struct xenbus_driver *drv;
+ struct xenbus_device *xdev;
+
+ DPRINTK("");
+
+ 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);
+ if (err)
+ printk(KERN_WARNING
+ "xenbus: suspend %s failed: %i\n", dev->bus_id, err);
+ return 0;
+}
+
+static int suspend_cancel_dev(struct device *dev, void *data)
+{
+ int err = 0;
+ struct xenbus_driver *drv;
+ struct xenbus_device *xdev;
+
+ DPRINTK("");
+
+ if (dev->driver == NULL)
+ return 0;
+ drv = to_xenbus_driver(dev->driver);
+ xdev = container_of(dev, struct xenbus_device, dev);
+ if (drv->suspend_cancel)
+ err = drv->suspend_cancel(xdev);
+ if (err)
+ printk(KERN_WARNING
+ "xenbus: suspend_cancel %s failed: %i\n",
+ dev->bus_id, err);
+ return 0;
+}
+
+static int resume_dev(struct device *dev, void *data)
+{
+ int err;
+ struct xenbus_driver *drv;
+ struct xenbus_device *xdev;
+
+ DPRINTK("");
+
+ 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
+ "xenbus: resume (talk_to_otherend) %s failed: %i\n",
+ dev->bus_id, err);
+ return err;
+ }
+
+ xdev->state = XenbusStateInitialising;
+
+ if (drv->resume) {
+ err = drv->resume(xdev);
+ if (err) {
+ printk(KERN_WARNING
+ "xenbus: resume %s failed: %i\n",
+ dev->bus_id, err);
+ return err;
+ }
+ }
+
+ err = watch_otherend(xdev);
+ if (err) {
+ printk(KERN_WARNING
+ "xenbus_probe: resume (watch_otherend) %s failed: "
+ "%d.\n", dev->bus_id, err);
+ return err;
+ }
+
+ return 0;
+}
+
+void xenbus_suspend(void)
+{
+ DPRINTK("");
+
+ bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, suspend_dev);
+ xenbus_backend_suspend(suspend_dev);
+ xs_suspend();
+}
+EXPORT_SYMBOL_GPL(xenbus_suspend);
+
+void xenbus_resume(void)
+{
+ xb_init_comms();
+ xs_resume();
+ bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, resume_dev);
+ xenbus_backend_resume(resume_dev);
+}
+EXPORT_SYMBOL_GPL(xenbus_resume);
+
+void xenbus_suspend_cancel(void)
+{
+ xs_suspend_cancel();
+ bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, suspend_cancel_dev);
+ xenbus_backend_resume(suspend_cancel_dev);
+}
+EXPORT_SYMBOL_GPL(xenbus_suspend_cancel);
+
+/* A flag to determine if xenstored is 'ready' (i.e. has started) */
+int xenstored_ready = 0;
+
+
+int register_xenstore_notifier(struct notifier_block *nb)
+{
+ int ret = 0;
+
+ if (xenstored_ready > 0)
+ ret = nb->notifier_call(nb, 0, NULL);
+ else
+ blocking_notifier_chain_register(&xenstore_chain, nb);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(register_xenstore_notifier);
+
+void unregister_xenstore_notifier(struct notifier_block *nb)
+{
+ blocking_notifier_chain_unregister(&xenstore_chain, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
+
+void xenbus_probe(struct work_struct *unused)
+{
+ BUG_ON((xenstored_ready <= 0));
+
+ /* 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);
+}
+
+static int __init xenbus_probe_init(void)
+{
+ int err = 0;
+
+ DPRINTK("");
+
+ err = -ENODEV;
+ if (!is_running_on_xen())
+ 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;
+
+ /*
+ * Domain0 doesn't have a store_evtchn or store_mfn yet.
+ */
+ if (is_initial_xendomain()) {
+ /* dom0 not yet supported */
+ } else {
+ xenstored_ready = 1;
+ xen_store_evtchn = xen_start_info->store_evtchn;
+ xen_store_mfn = xen_start_info->store_mfn;
+ }
+ xen_store_interface = mfn_to_virt(xen_store_mfn);
+
+ /* Initialize the interface to xenstore. */
+ err = xs_init();
+ if (err) {
+ printk(KERN_WARNING
+ "XENBUS: Error initializing xenstore comms: %i\n", err);
+ goto out_unreg_back;
+ }
+
+ if (!is_initial_xendomain())
+ xenbus_probe(NULL);
+
+ return 0;
+
+ out_unreg_back:
+ xenbus_backend_bus_unregister();
+
+ out_unreg_front:
+ bus_unregister(&xenbus_frontend.bus);
+
+ out_error:
+ return err;
+}
+
+postcore_initcall(xenbus_probe_init);
+
+MODULE_LICENSE("GPL");
+
+static int is_disconnected_device(struct device *dev, void *data)
+{
+ struct xenbus_device *xendev = to_xenbus_device(dev);
+ struct device_driver *drv = data;
+
+ /*
+ * 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;
+
+ return (xendev->state != XenbusStateConnected);
+}
+
+static int exists_disconnected_device(struct device_driver *drv)
+{
+ return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
+ is_disconnected_device);
+}
+
+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) {
+ printk(KERN_WARNING "XENBUS: Timeout connecting "
+ "to device: %s (state %d)\n",
+ xendev->nodename, xendev->state);
+ }
+
+ return 0;
+}
+
+/* We only wait for device setup after most initcalls have run. */
+static int ready_to_wait_for_devices;
+
+/*
+ * On a 10 second 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 timeout = jiffies + 10*HZ;
+ struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
+
+ if (!ready_to_wait_for_devices || !is_running_on_xen())
+ return;
+
+ while (exists_disconnected_device(drv)) {
+ if (time_after(jiffies, timeout))
+ break;
+ schedule_timeout_interruptible(HZ/10);
+ }
+
+ bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
+ print_device_status);
+}
+
+#ifndef MODULE
+static int __init boot_wait_for_devices(void)
+{
+ ready_to_wait_for_devices = 1;
+ wait_for_devices(NULL);
+ return 0;
+}
+
+late_initcall(boot_wait_for_devices);
+#endif