1 #define DPRINTK(fmt, args...) \
2 pr_debug("xenbus_probe (%s:%d) " fmt ".\n", \
3 __func__, __LINE__, ##args)
5 #include <linux/kernel.h>
7 #include <linux/string.h>
8 #include <linux/ctype.h>
9 #include <linux/fcntl.h>
11 #include <linux/proc_fs.h>
12 #include <linux/notifier.h>
13 #include <linux/kthread.h>
14 #include <linux/mutex.h>
16 #include <linux/module.h>
19 #include <asm/pgtable.h>
20 #include <asm/xen/hypervisor.h>
21 #include <xen/xenbus.h>
22 #include <xen/events.h>
25 #include <xen/platform_pci.h>
27 #include "xenbus_comms.h"
28 #include "xenbus_probe.h"
31 /* device/<type>/<id> => <type>-<id> */
32 static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
34 nodename = strchr(nodename, '/');
35 if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
36 printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
40 strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
41 if (!strchr(bus_id, '/')) {
42 printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
45 *strchr(bus_id, '/') = '-';
49 /* device/<typename>/<name> */
50 static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
56 /* ignore console/0 */
57 if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) {
58 DPRINTK("Ignoring buggy device entry console/0");
62 nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
66 DPRINTK("%s", nodename);
68 err = xenbus_probe_node(bus, type, nodename);
73 static int xenbus_uevent_frontend(struct device *_dev,
74 struct kobj_uevent_env *env)
76 struct xenbus_device *dev = to_xenbus_device(_dev);
78 if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
85 static void backend_changed(struct xenbus_watch *watch,
86 const char **vec, unsigned int len)
88 xenbus_otherend_changed(watch, vec, len, 1);
91 static const struct dev_pm_ops xenbus_pm_ops = {
92 .suspend = xenbus_dev_suspend,
93 .resume = xenbus_dev_resume,
94 .freeze = xenbus_dev_suspend,
95 .thaw = xenbus_dev_cancel,
96 .restore = xenbus_dev_resume,
99 static struct xen_bus_type xenbus_frontend = {
101 .levels = 2, /* device/type/<id> */
102 .get_bus_id = frontend_bus_id,
103 .probe = xenbus_probe_frontend,
104 .otherend_changed = backend_changed,
107 .match = xenbus_match,
108 .uevent = xenbus_uevent_frontend,
109 .probe = xenbus_dev_probe,
110 .remove = xenbus_dev_remove,
111 .shutdown = xenbus_dev_shutdown,
112 .dev_attrs = xenbus_dev_attrs,
114 .pm = &xenbus_pm_ops,
118 static void frontend_changed(struct xenbus_watch *watch,
119 const char **vec, unsigned int len)
123 xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
127 /* We watch for devices appearing and vanishing. */
128 static struct xenbus_watch fe_watch = {
130 .callback = frontend_changed,
133 static int read_backend_details(struct xenbus_device *xendev)
135 return xenbus_read_otherend_details(xendev, "backend-id", "backend");
138 static int is_device_connecting(struct device *dev, void *data)
140 struct xenbus_device *xendev = to_xenbus_device(dev);
141 struct device_driver *drv = data;
142 struct xenbus_driver *xendrv;
145 * A device with no driver will never connect. We care only about
146 * devices which should currently be in the process of connecting.
151 /* Is this search limited to a particular driver? */
152 if (drv && (dev->driver != drv))
155 xendrv = to_xenbus_driver(dev->driver);
156 return (xendev->state < XenbusStateConnected ||
157 (xendev->state == XenbusStateConnected &&
158 xendrv->is_ready && !xendrv->is_ready(xendev)));
161 static int exists_connecting_device(struct device_driver *drv)
163 return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
164 is_device_connecting);
167 static int print_device_status(struct device *dev, void *data)
169 struct xenbus_device *xendev = to_xenbus_device(dev);
170 struct device_driver *drv = data;
172 /* Is this operation limited to a particular driver? */
173 if (drv && (dev->driver != drv))
177 /* Information only: is this too noisy? */
178 printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
180 } else if (xendev->state < XenbusStateConnected) {
181 enum xenbus_state rstate = XenbusStateUnknown;
182 if (xendev->otherend)
183 rstate = xenbus_read_driver_state(xendev->otherend);
184 printk(KERN_WARNING "XENBUS: Timeout connecting "
185 "to device: %s (local state %d, remote state %d)\n",
186 xendev->nodename, xendev->state, rstate);
192 /* We only wait for device setup after most initcalls have run. */
193 static int ready_to_wait_for_devices;
196 * On a 5-minute timeout, wait for all devices currently configured. We need
197 * to do this to guarantee that the filesystems and / or network devices
198 * needed for boot are available, before we can allow the boot to proceed.
200 * This needs to be on a late_initcall, to happen after the frontend device
201 * drivers have been initialised, but before the root fs is mounted.
203 * A possible improvement here would be to have the tools add a per-device
204 * flag to the store entry, indicating whether it is needed at boot time.
205 * This would allow people who knew what they were doing to accelerate their
206 * boot slightly, but of course needs tools or manual intervention to set up
207 * those flags correctly.
209 static void wait_for_devices(struct xenbus_driver *xendrv)
211 unsigned long start = jiffies;
212 struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
213 unsigned int seconds_waited = 0;
215 if (!ready_to_wait_for_devices || !xen_domain())
218 while (exists_connecting_device(drv)) {
219 if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
221 printk(KERN_WARNING "XENBUS: Waiting for "
222 "devices to initialise: ");
224 printk("%us...", 300 - seconds_waited);
225 if (seconds_waited == 300)
229 schedule_timeout_interruptible(HZ/10);
235 bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
236 print_device_status);
239 int xenbus_register_frontend(struct xenbus_driver *drv)
243 drv->read_otherend_details = read_backend_details;
245 ret = xenbus_register_driver_common(drv, &xenbus_frontend);
249 /* If this driver is loaded as a module wait for devices to attach. */
250 wait_for_devices(drv);
254 EXPORT_SYMBOL_GPL(xenbus_register_frontend);
256 static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
257 static int backend_state;
259 static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
260 const char **v, unsigned int l)
262 xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
263 printk(KERN_DEBUG "XENBUS: backend %s %s\n",
264 v[XS_WATCH_PATH], xenbus_strstate(backend_state));
265 wake_up(&backend_state_wq);
268 static void xenbus_reset_wait_for_backend(char *be, int expected)
271 timeout = wait_event_interruptible_timeout(backend_state_wq,
272 backend_state == expected, 5 * HZ);
274 printk(KERN_INFO "XENBUS: backend %s timed out.\n", be);
278 * Reset frontend if it is in Connected or Closed state.
279 * Wait for backend to catch up.
280 * State Connected happens during kdump, Closed after kexec.
282 static void xenbus_reset_frontend(char *fe, char *be, int be_state)
284 struct xenbus_watch be_watch;
286 printk(KERN_DEBUG "XENBUS: backend %s %s\n",
287 be, xenbus_strstate(be_state));
289 memset(&be_watch, 0, sizeof(be_watch));
290 be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
294 be_watch.callback = xenbus_reset_backend_state_changed;
295 backend_state = XenbusStateUnknown;
297 printk(KERN_INFO "XENBUS: triggering reconnect on %s\n", be);
298 register_xenbus_watch(&be_watch);
300 /* fall through to forward backend to state XenbusStateInitialising */
302 case XenbusStateConnected:
303 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
304 xenbus_reset_wait_for_backend(be, XenbusStateClosing);
306 case XenbusStateClosing:
307 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
308 xenbus_reset_wait_for_backend(be, XenbusStateClosed);
310 case XenbusStateClosed:
311 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
312 xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
315 unregister_xenbus_watch(&be_watch);
316 printk(KERN_INFO "XENBUS: reconnect done on %s\n", be);
317 kfree(be_watch.node);
320 static void xenbus_check_frontend(char *class, char *dev)
322 int be_state, fe_state, err;
323 char *backend, *frontend;
325 frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
329 err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
334 case XenbusStateConnected:
335 case XenbusStateClosed:
336 printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
337 frontend, xenbus_strstate(fe_state));
338 backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
339 if (!backend || IS_ERR(backend))
341 err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
343 xenbus_reset_frontend(frontend, backend, be_state);
353 static void xenbus_reset_state(void)
355 char **devclass, **dev;
356 int devclass_n, dev_n;
359 devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
360 if (IS_ERR(devclass))
363 for (i = 0; i < devclass_n; i++) {
364 dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
367 for (j = 0; j < dev_n; j++)
368 xenbus_check_frontend(devclass[i], dev[j]);
374 static int frontend_probe_and_watch(struct notifier_block *notifier,
378 /* reset devices in Connected or Closed state */
379 if (xen_hvm_domain())
380 xenbus_reset_state();
381 /* Enumerate devices in xenstore and watch for changes. */
382 xenbus_probe_devices(&xenbus_frontend);
383 register_xenbus_watch(&fe_watch);
389 static int __init xenbus_probe_frontend_init(void)
391 static struct notifier_block xenstore_notifier = {
392 .notifier_call = frontend_probe_and_watch
398 /* Register ourselves with the kernel bus subsystem */
399 err = bus_register(&xenbus_frontend.bus);
403 register_xenstore_notifier(&xenstore_notifier);
407 subsys_initcall(xenbus_probe_frontend_init);
410 static int __init boot_wait_for_devices(void)
412 if (xen_hvm_domain() && !xen_platform_pci_unplug)
415 ready_to_wait_for_devices = 1;
416 wait_for_devices(NULL);
420 late_initcall(boot_wait_for_devices);
423 MODULE_LICENSE("GPL");