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