drivers/xen/xenbus/xenbus_probe_frontend.c

   1 #define DPRINTK(fmt, args...)                           \
   2         pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
   3                  __func__, __LINE__, ##args)
   4
   5 #include <linux/kernel.h>
   6 #include <linux/err.h>
   7 #include <linux/string.h>
   8 #include <linux/ctype.h>
   9 #include <linux/fcntl.h>
  10 #include <linux/mm.h>
  11 #include <linux/proc_fs.h>
  12 #include <linux/notifier.h>
  13 #include <linux/kthread.h>
  14 #include <linux/mutex.h>
  15 #include <linux/io.h>
  16 #include <linux/module.h>
  17
  18 #include <asm/page.h>
  19 #include <asm/pgtable.h>
  20 #include <asm/xen/hypervisor.h>
  21 #include <xen/xenbus.h>
  22 #include <xen/events.h>
  23 #include <xen/page.h>
  24
  25 #include <xen/platform_pci.h>
  26
  27 #include "xenbus_comms.h"
  28 #include "xenbus_probe.h"
  29
  30
  31 /* device/<type>/<id> => <type>-<id> */
  32 static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
  33 {
  34         nodename = strchr(nodename, '/');
  35         if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
  36                 printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
  37                 return -EINVAL;
  38         }
  39
  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);
  43                 return -EINVAL;
  44         }
  45         *strchr(bus_id, '/') = '-';
  46         return 0;
  47 }
  48
  49 /* device/<typename>/<name> */
  50 static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
  51                                  const char *name)
  52 {
  53         char *nodename;
  54         int err;
  55
  56         nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
  57         if (!nodename)
  58                 return -ENOMEM;
  59
  60         DPRINTK("%s", nodename);
  61
  62         err = xenbus_probe_node(bus, type, nodename);
  63         kfree(nodename);
  64         return err;
  65 }
  66
  67 static int xenbus_uevent_frontend(struct device *_dev,
  68                                   struct kobj_uevent_env *env)
  69 {
  70         struct xenbus_device *dev = to_xenbus_device(_dev);
  71
  72         if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
  73                 return -ENOMEM;
  74
  75         return 0;
  76 }
  77
  78
  79 static void backend_changed(struct xenbus_watch *watch,
  80                             const char **vec, unsigned int len)
  81 {
  82         xenbus_otherend_changed(watch, vec, len, 1);
  83 }
  84
  85 static const struct dev_pm_ops xenbus_pm_ops = {
  86         .suspend        = xenbus_dev_suspend,
  87         .resume         = xenbus_dev_resume,
  88         .freeze         = xenbus_dev_suspend,
  89         .thaw           = xenbus_dev_cancel,
  90         .restore        = xenbus_dev_resume,
  91 };
  92
  93 static struct xen_bus_type xenbus_frontend = {
  94         .root = "device",
  95         .levels = 2,            /* device/type/<id> */
  96         .get_bus_id = frontend_bus_id,
  97         .probe = xenbus_probe_frontend,
  98         .otherend_changed = backend_changed,
  99         .bus = {
 100                 .name           = "xen",
 101                 .match          = xenbus_match,
 102                 .uevent         = xenbus_uevent_frontend,
 103                 .probe          = xenbus_dev_probe,
 104                 .remove         = xenbus_dev_remove,
 105                 .shutdown       = xenbus_dev_shutdown,
 106                 .dev_attrs      = xenbus_dev_attrs,
 107
 108                 .pm             = &xenbus_pm_ops,
 109         },
 110 };
 111
 112 static void frontend_changed(struct xenbus_watch *watch,
 113                              const char **vec, unsigned int len)
 114 {
 115         DPRINTK("");
 116
 117         xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
 118 }
 119
 120
 121 /* We watch for devices appearing and vanishing. */
 122 static struct xenbus_watch fe_watch = {
 123         .node = "device",
 124         .callback = frontend_changed,
 125 };
 126
 127 static int read_backend_details(struct xenbus_device *xendev)
 128 {
 129         return xenbus_read_otherend_details(xendev, "backend-id", "backend");
 130 }
 131
 132 static int is_device_connecting(struct device *dev, void *data)
 133 {
 134         struct xenbus_device *xendev = to_xenbus_device(dev);
 135         struct device_driver *drv = data;
 136         struct xenbus_driver *xendrv;
 137
 138         /*
 139          * A device with no driver will never connect. We care only about
 140          * devices which should currently be in the process of connecting.
 141          */
 142         if (!dev->driver)
 143                 return 0;
 144
 145         /* Is this search limited to a particular driver? */
 146         if (drv && (dev->driver != drv))
 147                 return 0;
 148
 149         xendrv = to_xenbus_driver(dev->driver);
 150         return (xendev->state < XenbusStateConnected ||
 151                 (xendev->state == XenbusStateConnected &&
 152                  xendrv->is_ready && !xendrv->is_ready(xendev)));
 153 }
 154
 155 static int exists_connecting_device(struct device_driver *drv)
 156 {
 157         return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
 158                                 is_device_connecting);
 159 }
 160
 161 static int print_device_status(struct device *dev, void *data)
 162 {
 163         struct xenbus_device *xendev = to_xenbus_device(dev);
 164         struct device_driver *drv = data;
 165
 166         /* Is this operation limited to a particular driver? */
 167         if (drv && (dev->driver != drv))
 168                 return 0;
 169
 170         if (!dev->driver) {
 171                 /* Information only: is this too noisy? */
 172                 printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
 173                        xendev->nodename);
 174         } else if (xendev->state < XenbusStateConnected) {
 175                 enum xenbus_state rstate = XenbusStateUnknown;
 176                 if (xendev->otherend)
 177                         rstate = xenbus_read_driver_state(xendev->otherend);
 178                 printk(KERN_WARNING "XENBUS: Timeout connecting "
 179                        "to device: %s (local state %d, remote state %d)\n",
 180                        xendev->nodename, xendev->state, rstate);
 181         }
 182
 183         return 0;
 184 }
 185
 186 /* We only wait for device setup after most initcalls have run. */
 187 static int ready_to_wait_for_devices;
 188
 189 /*
 190  * On a 5-minute timeout, wait for all devices currently configured.  We need
 191  * to do this to guarantee that the filesystems and / or network devices
 192  * needed for boot are available, before we can allow the boot to proceed.
 193  *
 194  * This needs to be on a late_initcall, to happen after the frontend device
 195  * drivers have been initialised, but before the root fs is mounted.
 196  *
 197  * A possible improvement here would be to have the tools add a per-device
 198  * flag to the store entry, indicating whether it is needed at boot time.
 199  * This would allow people who knew what they were doing to accelerate their
 200  * boot slightly, but of course needs tools or manual intervention to set up
 201  * those flags correctly.
 202  */
 203 static void wait_for_devices(struct xenbus_driver *xendrv)
 204 {
 205         unsigned long start = jiffies;
 206         struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
 207         unsigned int seconds_waited = 0;
 208
 209         if (!ready_to_wait_for_devices || !xen_domain())
 210                 return;
 211
 212         while (exists_connecting_device(drv)) {
 213                 if (time_after(jiffies, start + (seconds_waited+5)*HZ)) {
 214                         if (!seconds_waited)
 215                                 printk(KERN_WARNING "XENBUS: Waiting for "
 216                                        "devices to initialise: ");
 217                         seconds_waited += 5;
 218                         printk("%us...", 300 - seconds_waited);
 219                         if (seconds_waited == 300)
 220                                 break;
 221                 }
 222
 223                 schedule_timeout_interruptible(HZ/10);
 224         }
 225
 226         if (seconds_waited)
 227                 printk("\n");
 228
 229         bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
 230                          print_device_status);
 231 }
 232
 233 int xenbus_register_frontend(struct xenbus_driver *drv)
 234 {
 235         int ret;
 236
 237         drv->read_otherend_details = read_backend_details;
 238
 239         ret = xenbus_register_driver_common(drv, &xenbus_frontend);
 240         if (ret)
 241                 return ret;
 242
 243         /* If this driver is loaded as a module wait for devices to attach. */
 244         wait_for_devices(drv);
 245
 246         return 0;
 247 }
 248 EXPORT_SYMBOL_GPL(xenbus_register_frontend);
 249
 250 static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
 251 static int backend_state;
 252
 253 static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
 254                                         const char **v, unsigned int l)
 255 {
 256         xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
 257         printk(KERN_DEBUG "XENBUS: backend %s %s\n",
 258                         v[XS_WATCH_PATH], xenbus_strstate(backend_state));
 259         wake_up(&backend_state_wq);
 260 }
 261
 262 static void xenbus_reset_wait_for_backend(char *be, int expected)
 263 {
 264         long timeout;
 265         timeout = wait_event_interruptible_timeout(backend_state_wq,
 266                         backend_state == expected, 5 * HZ);
 267         if (timeout <= 0)
 268                 printk(KERN_INFO "XENBUS: backend %s timed out.\n", be);
 269 }
 270
 271 /*
 272  * Reset frontend if it is in Connected or Closed state.
 273  * Wait for backend to catch up.
 274  * State Connected happens during kdump, Closed after kexec.
 275  */
 276 static void xenbus_reset_frontend(char *fe, char *be, int be_state)
 277 {
 278         struct xenbus_watch be_watch;
 279
 280         printk(KERN_DEBUG "XENBUS: backend %s %s\n",
 281                         be, xenbus_strstate(be_state));
 282
 283         memset(&be_watch, 0, sizeof(be_watch));
 284         be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
 285         if (!be_watch.node)
 286                 return;
 287
 288         be_watch.callback = xenbus_reset_backend_state_changed;
 289         backend_state = XenbusStateUnknown;
 290
 291         printk(KERN_INFO "XENBUS: triggering reconnect on %s\n", be);
 292         register_xenbus_watch(&be_watch);
 293
 294         /* fall through to forward backend to state XenbusStateInitialising */
 295         switch (be_state) {
 296         case XenbusStateConnected:
 297                 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
 298                 xenbus_reset_wait_for_backend(be, XenbusStateClosing);
 299
 300         case XenbusStateClosing:
 301                 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
 302                 xenbus_reset_wait_for_backend(be, XenbusStateClosed);
 303
 304         case XenbusStateClosed:
 305                 xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
 306                 xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
 307         }
 308
 309         unregister_xenbus_watch(&be_watch);
 310         printk(KERN_INFO "XENBUS: reconnect done on %s\n", be);
 311         kfree(be_watch.node);
 312 }
 313
 314 static void xenbus_check_frontend(char *class, char *dev)
 315 {
 316         int be_state, fe_state, err;
 317         char *backend, *frontend;
 318
 319         frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
 320         if (!frontend)
 321                 return;
 322
 323         err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
 324         if (err != 1)
 325                 goto out;
 326
 327         switch (fe_state) {
 328         case XenbusStateConnected:
 329         case XenbusStateClosed:
 330                 printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
 331                                 frontend, xenbus_strstate(fe_state));
 332                 backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
 333                 if (!backend || IS_ERR(backend))
 334                         goto out;
 335                 err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
 336                 if (err == 1)
 337                         xenbus_reset_frontend(frontend, backend, be_state);
 338                 kfree(backend);
 339                 break;
 340         default:
 341                 break;
 342         }
 343 out:
 344         kfree(frontend);
 345 }
 346
 347 static void xenbus_reset_state(void)
 348 {
 349         char **devclass, **dev;
 350         int devclass_n, dev_n;
 351         int i, j;
 352
 353         devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
 354         if (IS_ERR(devclass))
 355                 return;
 356
 357         for (i = 0; i < devclass_n; i++) {
 358                 dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
 359                 if (IS_ERR(dev))
 360                         continue;
 361                 for (j = 0; j < dev_n; j++)
 362                         xenbus_check_frontend(devclass[i], dev[j]);
 363                 kfree(dev);
 364         }
 365         kfree(devclass);
 366 }
 367
 368 static int frontend_probe_and_watch(struct notifier_block *notifier,
 369                                    unsigned long event,
 370                                    void *data)
 371 {
 372         /* reset devices in Connected or Closed state */
 373         if (xen_hvm_domain())
 374                 xenbus_reset_state();
 375         /* Enumerate devices in xenstore and watch for changes. */
 376         xenbus_probe_devices(&xenbus_frontend);
 377         register_xenbus_watch(&fe_watch);
 378
 379         return NOTIFY_DONE;
 380 }
 381
 382
 383 static int __init xenbus_probe_frontend_init(void)
 384 {
 385         static struct notifier_block xenstore_notifier = {
 386                 .notifier_call = frontend_probe_and_watch
 387         };
 388         int err;
 389
 390         DPRINTK("");
 391
 392         /* Register ourselves with the kernel bus subsystem */
 393         err = bus_register(&xenbus_frontend.bus);
 394         if (err)
 395                 return err;
 396
 397         register_xenstore_notifier(&xenstore_notifier);
 398
 399         return 0;
 400 }
 401 subsys_initcall(xenbus_probe_frontend_init);
 402
 403 #ifndef MODULE
 404 static int __init boot_wait_for_devices(void)
 405 {
 406         if (xen_hvm_domain() && !xen_platform_pci_unplug)
 407                 return -ENODEV;
 408
 409         ready_to_wait_for_devices = 1;
 410         wait_for_devices(NULL);
 411         return 0;
 412 }
 413
 414 late_initcall(boot_wait_for_devices);
 415 #endif
 416
 417 MODULE_LICENSE("GPL");