1 /******************************************************************************
2 * Talks to Xen Store to figure out what devices we have.
4 * Copyright (C) 2005 Rusty Russell, IBM Corporation
5 * Copyright (C) 2005 Mike Wray, Hewlett-Packard
6 * Copyright (C) 2005, 2006 XenSource Ltd
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License version 2
10 * as published by the Free Software Foundation; or, when distributed
11 * separately from the Linux kernel or incorporated into other
12 * software packages, subject to the following license:
14 * Permission is hereby granted, free of charge, to any person obtaining a copy
15 * of this source file (the "Software"), to deal in the Software without
16 * restriction, including without limitation the rights to use, copy, modify,
17 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
18 * and to permit persons to whom the Software is furnished to do so, subject to
19 * the following conditions:
21 * The above copyright notice and this permission notice shall be included in
22 * all copies or substantial portions of the Software.
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
25 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
26 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
27 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
28 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
29 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
33 #define DPRINTK(fmt, args...) \
34 pr_debug("xenbus_probe (%s:%d) " fmt ".\n", \
35 __func__, __LINE__, ##args)
37 #include <linux/kernel.h>
38 #include <linux/err.h>
39 #include <linux/string.h>
40 #include <linux/ctype.h>
41 #include <linux/fcntl.h>
43 #include <linux/notifier.h>
44 #include <linux/kthread.h>
45 #include <linux/mutex.h>
49 #include <asm/pgtable.h>
50 #include <asm/xen/hypervisor.h>
51 #include <xen/xenbus.h>
52 #include <xen/events.h>
55 #include "xenbus_comms.h"
56 #include "xenbus_probe.h"
59 struct xenstore_domain_interface *xen_store_interface;
60 static unsigned long xen_store_mfn;
62 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
64 static void wait_for_devices(struct xenbus_driver *xendrv);
66 static int xenbus_probe_frontend(const char *type, const char *name);
68 static void xenbus_dev_shutdown(struct device *_dev);
70 /* If something in array of ids matches this device, return it. */
71 static const struct xenbus_device_id *
72 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
74 for (; *arr->devicetype != '\0'; arr++) {
75 if (!strcmp(arr->devicetype, dev->devicetype))
81 int xenbus_match(struct device *_dev, struct device_driver *_drv)
83 struct xenbus_driver *drv = to_xenbus_driver(_drv);
88 return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
91 /* device/<type>/<id> => <type>-<id> */
92 static int frontend_bus_id(char bus_id[BUS_ID_SIZE], const char *nodename)
94 nodename = strchr(nodename, '/');
95 if (!nodename || strlen(nodename + 1) >= BUS_ID_SIZE) {
96 printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
100 strlcpy(bus_id, nodename + 1, BUS_ID_SIZE);
101 if (!strchr(bus_id, '/')) {
102 printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
105 *strchr(bus_id, '/') = '-';
110 static void free_otherend_details(struct xenbus_device *dev)
112 kfree(dev->otherend);
113 dev->otherend = NULL;
117 static void free_otherend_watch(struct xenbus_device *dev)
119 if (dev->otherend_watch.node) {
120 unregister_xenbus_watch(&dev->otherend_watch);
121 kfree(dev->otherend_watch.node);
122 dev->otherend_watch.node = NULL;
127 int read_otherend_details(struct xenbus_device *xendev,
128 char *id_node, char *path_node)
130 int err = xenbus_gather(XBT_NIL, xendev->nodename,
131 id_node, "%i", &xendev->otherend_id,
132 path_node, NULL, &xendev->otherend,
135 xenbus_dev_fatal(xendev, err,
136 "reading other end details from %s",
140 if (strlen(xendev->otherend) == 0 ||
141 !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
142 xenbus_dev_fatal(xendev, -ENOENT,
143 "unable to read other end from %s. "
144 "missing or inaccessible.",
146 free_otherend_details(xendev);
154 static int read_backend_details(struct xenbus_device *xendev)
156 return read_otherend_details(xendev, "backend-id", "backend");
160 /* Bus type for frontend drivers. */
161 static struct xen_bus_type xenbus_frontend = {
163 .levels = 2, /* device/type/<id> */
164 .get_bus_id = frontend_bus_id,
165 .probe = xenbus_probe_frontend,
168 .match = xenbus_match,
169 .probe = xenbus_dev_probe,
170 .remove = xenbus_dev_remove,
171 .shutdown = xenbus_dev_shutdown,
175 static void otherend_changed(struct xenbus_watch *watch,
176 const char **vec, unsigned int len)
178 struct xenbus_device *dev =
179 container_of(watch, struct xenbus_device, otherend_watch);
180 struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
181 enum xenbus_state state;
183 /* Protect us against watches firing on old details when the otherend
184 details change, say immediately after a resume. */
185 if (!dev->otherend ||
186 strncmp(dev->otherend, vec[XS_WATCH_PATH],
187 strlen(dev->otherend))) {
188 dev_dbg(&dev->dev, "Ignoring watch at %s", vec[XS_WATCH_PATH]);
192 state = xenbus_read_driver_state(dev->otherend);
194 dev_dbg(&dev->dev, "state is %d, (%s), %s, %s",
195 state, xenbus_strstate(state), dev->otherend_watch.node,
199 * Ignore xenbus transitions during shutdown. This prevents us doing
200 * work that can fail e.g., when the rootfs is gone.
202 if (system_state > SYSTEM_RUNNING) {
203 struct xen_bus_type *bus = bus;
204 bus = container_of(dev->dev.bus, struct xen_bus_type, bus);
205 /* If we're frontend, drive the state machine to Closed. */
206 /* This should cause the backend to release our resources. */
207 if ((bus == &xenbus_frontend) && (state == XenbusStateClosing))
208 xenbus_frontend_closed(dev);
212 if (drv->otherend_changed)
213 drv->otherend_changed(dev, state);
217 static int talk_to_otherend(struct xenbus_device *dev)
219 struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
221 free_otherend_watch(dev);
222 free_otherend_details(dev);
224 return drv->read_otherend_details(dev);
228 static int watch_otherend(struct xenbus_device *dev)
230 return xenbus_watch_pathfmt(dev, &dev->otherend_watch, otherend_changed,
231 "%s/%s", dev->otherend, "state");
235 int xenbus_dev_probe(struct device *_dev)
237 struct xenbus_device *dev = to_xenbus_device(_dev);
238 struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
239 const struct xenbus_device_id *id;
242 DPRINTK("%s", dev->nodename);
249 id = match_device(drv->ids, dev);
255 err = talk_to_otherend(dev);
257 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
262 err = drv->probe(dev, id);
266 err = watch_otherend(dev);
268 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
275 xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
276 xenbus_switch_state(dev, XenbusStateClosed);
280 int xenbus_dev_remove(struct device *_dev)
282 struct xenbus_device *dev = to_xenbus_device(_dev);
283 struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
285 DPRINTK("%s", dev->nodename);
287 free_otherend_watch(dev);
288 free_otherend_details(dev);
293 xenbus_switch_state(dev, XenbusStateClosed);
297 static void xenbus_dev_shutdown(struct device *_dev)
299 struct xenbus_device *dev = to_xenbus_device(_dev);
300 unsigned long timeout = 5*HZ;
302 DPRINTK("%s", dev->nodename);
304 get_device(&dev->dev);
305 if (dev->state != XenbusStateConnected) {
306 printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
307 dev->nodename, xenbus_strstate(dev->state));
310 xenbus_switch_state(dev, XenbusStateClosing);
311 timeout = wait_for_completion_timeout(&dev->down, timeout);
313 printk(KERN_INFO "%s: %s timeout closing device\n",
314 __func__, dev->nodename);
316 put_device(&dev->dev);
319 int xenbus_register_driver_common(struct xenbus_driver *drv,
320 struct xen_bus_type *bus,
321 struct module *owner,
322 const char *mod_name)
324 drv->driver.name = drv->name;
325 drv->driver.bus = &bus->bus;
326 drv->driver.owner = owner;
327 drv->driver.mod_name = mod_name;
329 return driver_register(&drv->driver);
332 int __xenbus_register_frontend(struct xenbus_driver *drv,
333 struct module *owner, const char *mod_name)
337 drv->read_otherend_details = read_backend_details;
339 ret = xenbus_register_driver_common(drv, &xenbus_frontend,
344 /* If this driver is loaded as a module wait for devices to attach. */
345 wait_for_devices(drv);
349 EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
351 void xenbus_unregister_driver(struct xenbus_driver *drv)
353 driver_unregister(&drv->driver);
355 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
359 struct xenbus_device *dev;
360 const char *nodename;
363 static int cmp_dev(struct device *dev, void *data)
365 struct xenbus_device *xendev = to_xenbus_device(dev);
366 struct xb_find_info *info = data;
368 if (!strcmp(xendev->nodename, info->nodename)) {
376 struct xenbus_device *xenbus_device_find(const char *nodename,
377 struct bus_type *bus)
379 struct xb_find_info info = { .dev = NULL, .nodename = nodename };
381 bus_for_each_dev(bus, NULL, &info, cmp_dev);
385 static int cleanup_dev(struct device *dev, void *data)
387 struct xenbus_device *xendev = to_xenbus_device(dev);
388 struct xb_find_info *info = data;
389 int len = strlen(info->nodename);
391 DPRINTK("%s", info->nodename);
393 /* Match the info->nodename path, or any subdirectory of that path. */
394 if (strncmp(xendev->nodename, info->nodename, len))
397 /* If the node name is longer, ensure it really is a subdirectory. */
398 if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
406 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
408 struct xb_find_info info = { .nodename = path };
412 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
414 device_unregister(&info.dev->dev);
415 put_device(&info.dev->dev);
420 static void xenbus_dev_release(struct device *dev)
423 kfree(to_xenbus_device(dev));
426 static ssize_t xendev_show_nodename(struct device *dev,
427 struct device_attribute *attr, char *buf)
429 return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
431 DEVICE_ATTR(nodename, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_nodename, NULL);
433 static ssize_t xendev_show_devtype(struct device *dev,
434 struct device_attribute *attr, char *buf)
436 return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
438 DEVICE_ATTR(devtype, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_devtype, NULL);
441 int xenbus_probe_node(struct xen_bus_type *bus,
443 const char *nodename)
446 struct xenbus_device *xendev;
450 enum xenbus_state state = xenbus_read_driver_state(nodename);
452 if (state != XenbusStateInitialising) {
453 /* Device is not new, so ignore it. This can happen if a
454 device is going away after switching to Closed. */
458 stringlen = strlen(nodename) + 1 + strlen(type) + 1;
459 xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
463 xendev->state = XenbusStateInitialising;
465 /* Copy the strings into the extra space. */
467 tmpstring = (char *)(xendev + 1);
468 strcpy(tmpstring, nodename);
469 xendev->nodename = tmpstring;
471 tmpstring += strlen(tmpstring) + 1;
472 strcpy(tmpstring, type);
473 xendev->devicetype = tmpstring;
474 init_completion(&xendev->down);
476 xendev->dev.bus = &bus->bus;
477 xendev->dev.release = xenbus_dev_release;
479 err = bus->get_bus_id(xendev->dev.bus_id, xendev->nodename);
483 /* Register with generic device framework. */
484 err = device_register(&xendev->dev);
488 err = device_create_file(&xendev->dev, &dev_attr_nodename);
490 goto fail_unregister;
492 err = device_create_file(&xendev->dev, &dev_attr_devtype);
494 goto fail_remove_file;
498 device_remove_file(&xendev->dev, &dev_attr_nodename);
500 device_unregister(&xendev->dev);
506 /* device/<typename>/<name> */
507 static int xenbus_probe_frontend(const char *type, const char *name)
512 nodename = kasprintf(GFP_KERNEL, "%s/%s/%s",
513 xenbus_frontend.root, type, name);
517 DPRINTK("%s", nodename);
519 err = xenbus_probe_node(&xenbus_frontend, type, nodename);
524 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
528 unsigned int dir_n = 0;
531 dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
535 for (i = 0; i < dir_n; i++) {
536 err = bus->probe(type, dir[i]);
544 int xenbus_probe_devices(struct xen_bus_type *bus)
548 unsigned int i, dir_n;
550 dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
554 for (i = 0; i < dir_n; i++) {
555 err = xenbus_probe_device_type(bus, dir[i]);
563 static unsigned int char_count(const char *str, char c)
565 unsigned int i, ret = 0;
567 for (i = 0; str[i]; i++)
573 static int strsep_len(const char *str, char c, unsigned int len)
577 for (i = 0; str[i]; i++)
583 return (len == 0) ? i : -ERANGE;
586 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
589 struct xenbus_device *dev;
590 char type[BUS_ID_SIZE];
591 const char *p, *root;
593 if (char_count(node, '/') < 2)
596 exists = xenbus_exists(XBT_NIL, node, "");
598 xenbus_cleanup_devices(node, &bus->bus);
602 /* backend/<type>/... or device/<type>/... */
603 p = strchr(node, '/') + 1;
604 snprintf(type, BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
605 type[BUS_ID_SIZE-1] = '\0';
607 rootlen = strsep_len(node, '/', bus->levels);
610 root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
614 dev = xenbus_device_find(root, &bus->bus);
616 xenbus_probe_node(bus, type, root);
618 put_device(&dev->dev);
623 static void frontend_changed(struct xenbus_watch *watch,
624 const char **vec, unsigned int len)
628 xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
631 /* We watch for devices appearing and vanishing. */
632 static struct xenbus_watch fe_watch = {
634 .callback = frontend_changed,
637 static int suspend_dev(struct device *dev, void *data)
640 struct xenbus_driver *drv;
641 struct xenbus_device *xdev;
645 if (dev->driver == NULL)
647 drv = to_xenbus_driver(dev->driver);
648 xdev = container_of(dev, struct xenbus_device, dev);
650 err = drv->suspend(xdev);
653 "xenbus: suspend %s failed: %i\n", dev->bus_id, err);
657 static int suspend_cancel_dev(struct device *dev, void *data)
660 struct xenbus_driver *drv;
661 struct xenbus_device *xdev;
665 if (dev->driver == NULL)
667 drv = to_xenbus_driver(dev->driver);
668 xdev = container_of(dev, struct xenbus_device, dev);
669 if (drv->suspend_cancel)
670 err = drv->suspend_cancel(xdev);
673 "xenbus: suspend_cancel %s failed: %i\n",
678 static int resume_dev(struct device *dev, void *data)
681 struct xenbus_driver *drv;
682 struct xenbus_device *xdev;
686 if (dev->driver == NULL)
689 drv = to_xenbus_driver(dev->driver);
690 xdev = container_of(dev, struct xenbus_device, dev);
692 err = talk_to_otherend(xdev);
695 "xenbus: resume (talk_to_otherend) %s failed: %i\n",
700 xdev->state = XenbusStateInitialising;
703 err = drv->resume(xdev);
706 "xenbus: resume %s failed: %i\n",
712 err = watch_otherend(xdev);
715 "xenbus_probe: resume (watch_otherend) %s failed: "
716 "%d.\n", dev->bus_id, err);
723 void xenbus_suspend(void)
727 bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, suspend_dev);
728 xenbus_backend_suspend(suspend_dev);
731 EXPORT_SYMBOL_GPL(xenbus_suspend);
733 void xenbus_resume(void)
737 bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, resume_dev);
738 xenbus_backend_resume(resume_dev);
740 EXPORT_SYMBOL_GPL(xenbus_resume);
742 void xenbus_suspend_cancel(void)
745 bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, suspend_cancel_dev);
746 xenbus_backend_resume(suspend_cancel_dev);
748 EXPORT_SYMBOL_GPL(xenbus_suspend_cancel);
750 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
751 int xenstored_ready = 0;
754 int register_xenstore_notifier(struct notifier_block *nb)
758 if (xenstored_ready > 0)
759 ret = nb->notifier_call(nb, 0, NULL);
761 blocking_notifier_chain_register(&xenstore_chain, nb);
765 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
767 void unregister_xenstore_notifier(struct notifier_block *nb)
769 blocking_notifier_chain_unregister(&xenstore_chain, nb);
771 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
773 void xenbus_probe(struct work_struct *unused)
775 BUG_ON((xenstored_ready <= 0));
777 /* Enumerate devices in xenstore and watch for changes. */
778 xenbus_probe_devices(&xenbus_frontend);
779 register_xenbus_watch(&fe_watch);
780 xenbus_backend_probe_and_watch();
782 /* Notify others that xenstore is up */
783 blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
786 static int __init xenbus_probe_init(void)
793 if (!is_running_on_xen())
796 /* Register ourselves with the kernel bus subsystem */
797 err = bus_register(&xenbus_frontend.bus);
801 err = xenbus_backend_bus_register();
803 goto out_unreg_front;
806 * Domain0 doesn't have a store_evtchn or store_mfn yet.
808 if (is_initial_xendomain()) {
809 /* dom0 not yet supported */
812 xen_store_evtchn = xen_start_info->store_evtchn;
813 xen_store_mfn = xen_start_info->store_mfn;
815 xen_store_interface = mfn_to_virt(xen_store_mfn);
817 /* Initialize the interface to xenstore. */
821 "XENBUS: Error initializing xenstore comms: %i\n", err);
825 if (!is_initial_xendomain())
831 xenbus_backend_bus_unregister();
834 bus_unregister(&xenbus_frontend.bus);
840 postcore_initcall(xenbus_probe_init);
842 MODULE_LICENSE("GPL");
844 static int is_disconnected_device(struct device *dev, void *data)
846 struct xenbus_device *xendev = to_xenbus_device(dev);
847 struct device_driver *drv = data;
850 * A device with no driver will never connect. We care only about
851 * devices which should currently be in the process of connecting.
856 /* Is this search limited to a particular driver? */
857 if (drv && (dev->driver != drv))
860 return (xendev->state != XenbusStateConnected);
863 static int exists_disconnected_device(struct device_driver *drv)
865 return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
866 is_disconnected_device);
869 static int print_device_status(struct device *dev, void *data)
871 struct xenbus_device *xendev = to_xenbus_device(dev);
872 struct device_driver *drv = data;
874 /* Is this operation limited to a particular driver? */
875 if (drv && (dev->driver != drv))
879 /* Information only: is this too noisy? */
880 printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
882 } else if (xendev->state != XenbusStateConnected) {
883 printk(KERN_WARNING "XENBUS: Timeout connecting "
884 "to device: %s (state %d)\n",
885 xendev->nodename, xendev->state);
891 /* We only wait for device setup after most initcalls have run. */
892 static int ready_to_wait_for_devices;
895 * On a 10 second timeout, wait for all devices currently configured. We need
896 * to do this to guarantee that the filesystems and / or network devices
897 * needed for boot are available, before we can allow the boot to proceed.
899 * This needs to be on a late_initcall, to happen after the frontend device
900 * drivers have been initialised, but before the root fs is mounted.
902 * A possible improvement here would be to have the tools add a per-device
903 * flag to the store entry, indicating whether it is needed at boot time.
904 * This would allow people who knew what they were doing to accelerate their
905 * boot slightly, but of course needs tools or manual intervention to set up
906 * those flags correctly.
908 static void wait_for_devices(struct xenbus_driver *xendrv)
910 unsigned long timeout = jiffies + 10*HZ;
911 struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
913 if (!ready_to_wait_for_devices || !is_running_on_xen())
916 while (exists_disconnected_device(drv)) {
917 if (time_after(jiffies, timeout))
919 schedule_timeout_interruptible(HZ/10);
922 bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
923 print_device_status);
927 static int __init boot_wait_for_devices(void)
929 ready_to_wait_for_devices = 1;
930 wait_for_devices(NULL);
934 late_initcall(boot_wait_for_devices);