[deliverable/linux.git] / drivers / xen / xenbus / xenbus_probe_frontend.c

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#define DPRINTK(fmt, ...)				\
	pr_debug("(%s:%d) " fmt "\n",			\
		 __func__, __LINE__, ##__VA_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/proc_fs.h>
#include <linux/notifier.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <linux/module.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 <xen/xen.h>

#include <xen/platform_pci.h>

#include "xenbus_comms.h"
#include "xenbus_probe.h"


static struct workqueue_struct *xenbus_frontend_wq;

/* device/<type>/<id> => <type>-<id> */
static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
{
	nodename = strchr(nodename, '/');
	if (!nodename || strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
		pr_warn("bad frontend %s\n", nodename);
		return -EINVAL;
	}

	strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
	if (!strchr(bus_id, '/')) {
		pr_warn("bus_id %s no slash\n", bus_id);
		return -EINVAL;
	}
	*strchr(bus_id, '/') = '-';
	return 0;
}

/* device/<typename>/<name> */
static int xenbus_probe_frontend(struct xen_bus_type *bus, const char *type,
				 const char *name)
{
	char *nodename;
	int err;

	/* ignore console/0 */
	if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) {
		DPRINTK("Ignoring buggy device entry console/0");
		return 0;
	}

	nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
	if (!nodename)
		return -ENOMEM;

	DPRINTK("%s", nodename);

	err = xenbus_probe_node(bus, type, nodename);
	kfree(nodename);
	return err;
}

static int xenbus_uevent_frontend(struct device *_dev,
				  struct kobj_uevent_env *env)
{
	struct xenbus_device *dev = to_xenbus_device(_dev);

	if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
		return -ENOMEM;

	return 0;
}


static void backend_changed(struct xenbus_watch *watch,
			    const char **vec, unsigned int len)
{
	xenbus_otherend_changed(watch, vec, len, 1);
}

static void xenbus_frontend_delayed_resume(struct work_struct *w)
{
	struct xenbus_device *xdev = container_of(w, struct xenbus_device, work);

	xenbus_dev_resume(&xdev->dev);
}

static int xenbus_frontend_dev_resume(struct device *dev)
{
	/*
	 * If xenstored is running in this domain, we cannot access the backend
	 * state at the moment, so we need to defer xenbus_dev_resume
	 */
	if (xen_store_domain_type == XS_LOCAL) {
		struct xenbus_device *xdev = to_xenbus_device(dev);

		if (!xenbus_frontend_wq) {
			pr_err("%s: no workqueue to process delayed resume\n",
			       xdev->nodename);
			return -EFAULT;
		}

		INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume);
		queue_work(xenbus_frontend_wq, &xdev->work);

		return 0;
	}

	return xenbus_dev_resume(dev);
}

static const struct dev_pm_ops xenbus_pm_ops = {
	.suspend	= xenbus_dev_suspend,
	.resume		= xenbus_frontend_dev_resume,
	.freeze		= xenbus_dev_suspend,
	.thaw		= xenbus_dev_cancel,
	.restore	= xenbus_dev_resume,
};

static struct xen_bus_type xenbus_frontend = {
	.root = "device",
	.levels = 2,		/* device/type/<id> */
	.get_bus_id = frontend_bus_id,
	.probe = xenbus_probe_frontend,
	.otherend_changed = backend_changed,
	.bus = {
		.name		= "xen",
		.match		= xenbus_match,
		.uevent		= xenbus_uevent_frontend,
		.probe		= xenbus_dev_probe,
		.remove		= xenbus_dev_remove,
		.shutdown	= xenbus_dev_shutdown,
		.dev_attrs	= xenbus_dev_attrs,

		.pm		= &xenbus_pm_ops,
	},
};

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 read_backend_details(struct xenbus_device *xendev)
{
	return xenbus_read_otherend_details(xendev, "backend-id", "backend");
}

static int is_device_connecting(struct device *dev, void *data, bool ignore_nonessential)
{
	struct xenbus_device *xendev = to_xenbus_device(dev);
	struct device_driver *drv = data;
	struct xenbus_driver *xendrv;

	/*
	 * 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;

	if (ignore_nonessential) {
		/* With older QEMU, for PVonHVM guests the guest config files
		 * could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
		 * which is nonsensical as there is no PV FB (there can be
		 * a PVKB) running as HVM guest. */

		if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
			return 0;

		if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
			return 0;
	}
	xendrv = to_xenbus_driver(dev->driver);
	return (xendev->state < XenbusStateConnected ||
		(xendev->state == XenbusStateConnected &&
		 xendrv->is_ready && !xendrv->is_ready(xendev)));
}
static int essential_device_connecting(struct device *dev, void *data)
{
	return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);
}
static int non_essential_device_connecting(struct device *dev, void *data)
{
	return is_device_connecting(dev, data, false);
}

static int exists_essential_connecting_device(struct device_driver *drv)
{
	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
				essential_device_connecting);
}
static int exists_non_essential_connecting_device(struct device_driver *drv)
{
	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
				non_essential_device_connecting);
}

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? */
		pr_info("Device with no driver: %s\n", xendev->nodename);
	} else if (xendev->state < XenbusStateConnected) {
		enum xenbus_state rstate = XenbusStateUnknown;
		if (xendev->otherend)
			rstate = xenbus_read_driver_state(xendev->otherend);
		pr_warn("Timeout connecting to device: %s (local state %d, remote state %d)\n",
			xendev->nodename, xendev->state, rstate);
	}

	return 0;
}

/* We only wait for device setup after most initcalls have run. */
static int ready_to_wait_for_devices;

static bool wait_loop(unsigned long start, unsigned int max_delay,
		     unsigned int *seconds_waited)
{
	if (time_after(jiffies, start + (*seconds_waited+5)*HZ)) {
		if (!*seconds_waited)
			pr_warn("Waiting for devices to initialise: ");
		*seconds_waited += 5;
		pr_cont("%us...", max_delay - *seconds_waited);
		if (*seconds_waited == max_delay) {
			pr_cont("\n");
			return true;
		}
	}

	schedule_timeout_interruptible(HZ/10);

	return false;
}
/*
 * On a 5-minute 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 start = jiffies;
	struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
	unsigned int seconds_waited = 0;

	if (!ready_to_wait_for_devices || !xen_domain())
		return;

	while (exists_non_essential_connecting_device(drv))
		if (wait_loop(start, 30, &seconds_waited))
			break;

	/* Skips PVKB and PVFB check.*/
	while (exists_essential_connecting_device(drv))
		if (wait_loop(start, 270, &seconds_waited))
			break;

	if (seconds_waited)
		printk("\n");

	bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
			 print_device_status);
}

int xenbus_register_frontend(struct xenbus_driver *drv)
{
	int ret;

	drv->read_otherend_details = read_backend_details;

	ret = xenbus_register_driver_common(drv, &xenbus_frontend);
	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);

static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
static int backend_state;

static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
					const char **v, unsigned int l)
{
	xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
			v[XS_WATCH_PATH], xenbus_strstate(backend_state));
	wake_up(&backend_state_wq);
}

static void xenbus_reset_wait_for_backend(char *be, int expected)
{
	long timeout;
	timeout = wait_event_interruptible_timeout(backend_state_wq,
			backend_state == expected, 5 * HZ);
	if (timeout <= 0)
		pr_info("backend %s timed out\n", be);
}

/*
 * Reset frontend if it is in Connected or Closed state.
 * Wait for backend to catch up.
 * State Connected happens during kdump, Closed after kexec.
 */
static void xenbus_reset_frontend(char *fe, char *be, int be_state)
{
	struct xenbus_watch be_watch;

	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
			be, xenbus_strstate(be_state));

	memset(&be_watch, 0, sizeof(be_watch));
	be_watch.node = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/state", be);
	if (!be_watch.node)
		return;

	be_watch.callback = xenbus_reset_backend_state_changed;
	backend_state = XenbusStateUnknown;

	pr_info("triggering reconnect on %s\n", be);
	register_xenbus_watch(&be_watch);

	/* fall through to forward backend to state XenbusStateInitialising */
	switch (be_state) {
	case XenbusStateConnected:
		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
		xenbus_reset_wait_for_backend(be, XenbusStateClosing);

	case XenbusStateClosing:
		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
		xenbus_reset_wait_for_backend(be, XenbusStateClosed);

	case XenbusStateClosed:
		xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
		xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
	}

	unregister_xenbus_watch(&be_watch);
	pr_info("reconnect done on %s\n", be);
	kfree(be_watch.node);
}

static void xenbus_check_frontend(char *class, char *dev)
{
	int be_state, fe_state, err;
	char *backend, *frontend;

	frontend = kasprintf(GFP_NOIO | __GFP_HIGH, "device/%s/%s", class, dev);
	if (!frontend)
		return;

	err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
	if (err != 1)
		goto out;

	switch (fe_state) {
	case XenbusStateConnected:
	case XenbusStateClosed:
		printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
				frontend, xenbus_strstate(fe_state));
		backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
		if (!backend || IS_ERR(backend))
			goto out;
		err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
		if (err == 1)
			xenbus_reset_frontend(frontend, backend, be_state);
		kfree(backend);
		break;
	default:
		break;
	}
out:
	kfree(frontend);
}

static void xenbus_reset_state(void)
{
	char **devclass, **dev;
	int devclass_n, dev_n;
	int i, j;

	devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
	if (IS_ERR(devclass))
		return;

	for (i = 0; i < devclass_n; i++) {
		dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
		if (IS_ERR(dev))
			continue;
		for (j = 0; j < dev_n; j++)
			xenbus_check_frontend(devclass[i], dev[j]);
		kfree(dev);
	}
	kfree(devclass);
}

static int frontend_probe_and_watch(struct notifier_block *notifier,
				   unsigned long event,
				   void *data)
{
	/* reset devices in Connected or Closed state */
	if (xen_hvm_domain())
		xenbus_reset_state();
	/* Enumerate devices in xenstore and watch for changes. */
	xenbus_probe_devices(&xenbus_frontend);
	register_xenbus_watch(&fe_watch);

	return NOTIFY_DONE;
}


static int __init xenbus_probe_frontend_init(void)
{
	static struct notifier_block xenstore_notifier = {
		.notifier_call = frontend_probe_and_watch
	};
	int err;

	DPRINTK("");

	/* Register ourselves with the kernel bus subsystem */
	err = bus_register(&xenbus_frontend.bus);
	if (err)
		return err;

	register_xenstore_notifier(&xenstore_notifier);

	xenbus_frontend_wq = create_workqueue("xenbus_frontend");

	return 0;
}
subsys_initcall(xenbus_probe_frontend_init);

#ifndef MODULE
static int __init boot_wait_for_devices(void)
{
	if (xen_hvm_domain() && !xen_platform_pci_unplug)
		return -ENODEV;

	ready_to_wait_for_devices = 1;
	wait_for_devices(NULL);
	return 0;
}

late_initcall(boot_wait_for_devices);
#endif

MODULE_LICENSE("GPL");
Commit	Line	Data
283c0972 JP	1	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	2
	3	#define DPRINTK(fmt, ...) \
	4	pr_debug("(%s:%d) " fmt "\n", \
	5	__func__, __LINE__, ##__VA_ARGS__)
2de06cc1 IC	6
	7	#include <linux/kernel.h>
	8	#include <linux/err.h>
	9	#include <linux/string.h>
	10	#include <linux/ctype.h>
	11	#include <linux/fcntl.h>
	12	#include <linux/mm.h>
	13	#include <linux/proc_fs.h>
	14	#include <linux/notifier.h>
	15	#include <linux/kthread.h>
	16	#include <linux/mutex.h>
	17	#include <linux/io.h>
72ee5112	18	#include <linux/module.h>
2de06cc1 IC	19
	20	#include <asm/page.h>
	21	#include <asm/pgtable.h>
	22	#include <asm/xen/hypervisor.h>
	23	#include <xen/xenbus.h>
	24	#include <xen/events.h>
	25	#include <xen/page.h>
4d9310e3	26	#include <xen/xen.h>
2de06cc1 IC	27
	28	#include <xen/platform_pci.h>
	29
	30	#include "xenbus_comms.h"
	31	#include "xenbus_probe.h"
	32
	33
2abb2746 AC	34	static struct workqueue_struct *xenbus_frontend_wq;
2abb2746 AC	35
2de06cc1 IC	36	/* device/<type>/<id> => <type>-<id> */
	37	static int frontend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
	38	{
	39	nodename = strchr(nodename, '/');
	40	if (!nodename \|\| strlen(nodename + 1) >= XEN_BUS_ID_SIZE) {
283c0972	41	pr_warn("bad frontend %s\n", nodename);
2de06cc1 IC	42	return -EINVAL;
	43	}
	44
	45	strlcpy(bus_id, nodename + 1, XEN_BUS_ID_SIZE);
	46	if (!strchr(bus_id, '/')) {
283c0972	47	pr_warn("bus_id %s no slash\n", bus_id);
2de06cc1 IC	48	return -EINVAL;
	49	}
	50	*strchr(bus_id, '/') = '-';
	51	return 0;
	52	}
	53
	54	/* device/<typename>/<name> */
6bac7f9f IC	55	static int xenbus_probe_frontend(struct xen_bus_type bus, const char type,
6bac7f9f IC	56	const char *name)
2de06cc1 IC	57	{
	58	char *nodename;
	59	int err;
	60
42c46e6b SS	61	/* ignore console/0 */
	62	if (!strncmp(type, "console", 7) && !strncmp(name, "0", 1)) {
	63	DPRINTK("Ignoring buggy device entry console/0");
	64	return 0;
	65	}
	66
2de06cc1 IC	67	nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, name);
	68	if (!nodename)
	69	return -ENOMEM;
	70
	71	DPRINTK("%s", nodename);
	72
	73	err = xenbus_probe_node(bus, type, nodename);
	74	kfree(nodename);
	75	return err;
	76	}
	77
6bac7f9f IC	78	static int xenbus_uevent_frontend(struct device *_dev,
6bac7f9f IC	79	struct kobj_uevent_env *env)
df660251 IC	80	{
	81	struct xenbus_device *dev = to_xenbus_device(_dev);
	82
	83	if (add_uevent_var(env, "MODALIAS=xen:%s", dev->devicetype))
	84	return -ENOMEM;
	85
	86	return 0;
	87	}
	88
	89
2de06cc1 IC	90	static void backend_changed(struct xenbus_watch *watch,
	91	const char **vec, unsigned int len)
	92	{
	93	xenbus_otherend_changed(watch, vec, len, 1);
	94	}
	95
2abb2746 AC	96	static void xenbus_frontend_delayed_resume(struct work_struct *w)
	97	{
	98	struct xenbus_device *xdev = container_of(w, struct xenbus_device, work);
	99
	100	xenbus_dev_resume(&xdev->dev);
	101	}
	102
	103	static int xenbus_frontend_dev_resume(struct device *dev)
	104	{
	105	/*
	106	* If xenstored is running in this domain, we cannot access the backend
	107	* state at the moment, so we need to defer xenbus_dev_resume
	108	*/
	109	if (xen_store_domain_type == XS_LOCAL) {
	110	struct xenbus_device *xdev = to_xenbus_device(dev);
	111
	112	if (!xenbus_frontend_wq) {
	113	pr_err("%s: no workqueue to process delayed resume\n",
	114	xdev->nodename);
	115	return -EFAULT;
	116	}
	117
	118	INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume);
	119	queue_work(xenbus_frontend_wq, &xdev->work);
	120
	121	return 0;
	122	}
	123
	124	return xenbus_dev_resume(dev);
	125	}
	126
c7853aea	127	static const struct dev_pm_ops xenbus_pm_ops = {
b3e96c0c	128	.suspend = xenbus_dev_suspend,
2abb2746	129	.resume = xenbus_frontend_dev_resume,
b3e96c0c SR	130	.freeze = xenbus_dev_suspend,
	131	.thaw = xenbus_dev_cancel,
	132	.restore = xenbus_dev_resume,
c7853aea KS	133	};
c7853aea KS	134
2de06cc1 IC	135	static struct xen_bus_type xenbus_frontend = {
2de06cc1 IC	136	.root = "device",
6bac7f9f	137	.levels = 2, /* device/type/<id> */
2de06cc1 IC	138	.get_bus_id = frontend_bus_id,
	139	.probe = xenbus_probe_frontend,
	140	.otherend_changed = backend_changed,
	141	.bus = {
6bac7f9f IC	142	.name = "xen",
	143	.match = xenbus_match,
	144	.uevent = xenbus_uevent_frontend,
	145	.probe = xenbus_dev_probe,
	146	.remove = xenbus_dev_remove,
	147	.shutdown = xenbus_dev_shutdown,
cc85e933	148	.dev_attrs = xenbus_dev_attrs,
6bac7f9f	149
c7853aea	150	.pm = &xenbus_pm_ops,
2de06cc1 IC	151	},
	152	};
	153
	154	static void frontend_changed(struct xenbus_watch *watch,
	155	const char **vec, unsigned int len)
	156	{
	157	DPRINTK("");
	158
	159	xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
	160	}
	161
	162
	163	/* We watch for devices appearing and vanishing. */
	164	static struct xenbus_watch fe_watch = {
	165	.node = "device",
	166	.callback = frontend_changed,
	167	};
	168
	169	static int read_backend_details(struct xenbus_device *xendev)
	170	{
	171	return xenbus_read_otherend_details(xendev, "backend-id", "backend");
	172	}
	173
3066616c	174	static int is_device_connecting(struct device dev, void data, bool ignore_nonessential)
2de06cc1 IC	175	{
	176	struct xenbus_device *xendev = to_xenbus_device(dev);
	177	struct device_driver *drv = data;
	178	struct xenbus_driver *xendrv;
	179
	180	/*
	181	* A device with no driver will never connect. We care only about
	182	* devices which should currently be in the process of connecting.
	183	*/
	184	if (!dev->driver)
	185	return 0;
	186
	187	/* Is this search limited to a particular driver? */
	188	if (drv && (dev->driver != drv))
	189	return 0;
	190
3066616c KRW	191	if (ignore_nonessential) {
	192	/* With older QEMU, for PVonHVM guests the guest config files
	193	* could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
	194	* which is nonsensical as there is no PV FB (there can be
	195	* a PVKB) running as HVM guest. */
	196
	197	if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
	198	return 0;
	199
	200	if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
	201	return 0;
	202	}
2de06cc1 IC	203	xendrv = to_xenbus_driver(dev->driver);
	204	return (xendev->state < XenbusStateConnected \|\|
	205	(xendev->state == XenbusStateConnected &&
	206	xendrv->is_ready && !xendrv->is_ready(xendev)));
	207	}
3066616c KRW	208	static int essential_device_connecting(struct device dev, void data)
	209	{
	210	return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);
	211	}
	212	static int non_essential_device_connecting(struct device dev, void data)
	213	{
	214	return is_device_connecting(dev, data, false);
	215	}
2de06cc1	216
3066616c	217	static int exists_essential_connecting_device(struct device_driver *drv)
2de06cc1 IC	218	{
2de06cc1 IC	219	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
3066616c KRW	220	essential_device_connecting);
	221	}
	222	static int exists_non_essential_connecting_device(struct device_driver *drv)
	223	{
	224	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
	225	non_essential_device_connecting);
2de06cc1 IC	226	}
	227
	228	static int print_device_status(struct device dev, void data)
	229	{
	230	struct xenbus_device *xendev = to_xenbus_device(dev);
	231	struct device_driver *drv = data;
	232
	233	/* Is this operation limited to a particular driver? */
	234	if (drv && (dev->driver != drv))
	235	return 0;
	236
	237	if (!dev->driver) {
	238	/* Information only: is this too noisy? */
283c0972	239	pr_info("Device with no driver: %s\n", xendev->nodename);
2de06cc1 IC	240	} else if (xendev->state < XenbusStateConnected) {
	241	enum xenbus_state rstate = XenbusStateUnknown;
	242	if (xendev->otherend)
	243	rstate = xenbus_read_driver_state(xendev->otherend);
283c0972 JP	244	pr_warn("Timeout connecting to device: %s (local state %d, remote state %d)\n",
283c0972 JP	245	xendev->nodename, xendev->state, rstate);
2de06cc1 IC	246	}
	247
	248	return 0;
	249	}
	250
	251	/* We only wait for device setup after most initcalls have run. */
	252	static int ready_to_wait_for_devices;
	253
3066616c KRW	254	static bool wait_loop(unsigned long start, unsigned int max_delay,
	255	unsigned int *seconds_waited)
	256	{
	257	if (time_after(jiffies, start + (seconds_waited+5)HZ)) {
	258	if (!*seconds_waited)
283c0972	259	pr_warn("Waiting for devices to initialise: ");
3066616c	260	*seconds_waited += 5;
283c0972 JP	261	pr_cont("%us...", max_delay - *seconds_waited);
	262	if (*seconds_waited == max_delay) {
	263	pr_cont("\n");
3066616c	264	return true;
283c0972	265	}
3066616c KRW	266	}
	267
	268	schedule_timeout_interruptible(HZ/10);
	269
	270	return false;
	271	}
2de06cc1 IC	272	/*
	273	* On a 5-minute timeout, wait for all devices currently configured. We need
	274	* to do this to guarantee that the filesystems and / or network devices
	275	* needed for boot are available, before we can allow the boot to proceed.
	276	*
	277	* This needs to be on a late_initcall, to happen after the frontend device
	278	* drivers have been initialised, but before the root fs is mounted.
	279	*
	280	* A possible improvement here would be to have the tools add a per-device
	281	* flag to the store entry, indicating whether it is needed at boot time.
	282	* This would allow people who knew what they were doing to accelerate their
	283	* boot slightly, but of course needs tools or manual intervention to set up
	284	* those flags correctly.
	285	*/
	286	static void wait_for_devices(struct xenbus_driver *xendrv)
	287	{
	288	unsigned long start = jiffies;
	289	struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
	290	unsigned int seconds_waited = 0;
	291
	292	if (!ready_to_wait_for_devices \|\| !xen_domain())
	293	return;
	294
3066616c KRW	295	while (exists_non_essential_connecting_device(drv))
	296	if (wait_loop(start, 30, &seconds_waited))
	297	break;
	298
	299	/* Skips PVKB and PVFB check.*/
	300	while (exists_essential_connecting_device(drv))
	301	if (wait_loop(start, 270, &seconds_waited))
	302	break;
2de06cc1 IC	303
	304	if (seconds_waited)
	305	printk("\n");
	306
	307	bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
	308	print_device_status);
	309	}
	310
73db144b	311	int xenbus_register_frontend(struct xenbus_driver *drv)
2de06cc1 IC	312	{
	313	int ret;
	314
	315	drv->read_otherend_details = read_backend_details;
	316
73db144b	317	ret = xenbus_register_driver_common(drv, &xenbus_frontend);
2de06cc1 IC	318	if (ret)
	319	return ret;
	320
	321	/* If this driver is loaded as a module wait for devices to attach. */
	322	wait_for_devices(drv);
	323
	324	return 0;
	325	}
73db144b	326	EXPORT_SYMBOL_GPL(xenbus_register_frontend);
2de06cc1	327
116df6f0 OH	328	static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
	329	static int backend_state;
	330
	331	static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
	332	const char **v, unsigned int l)
	333	{
	334	xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
	335	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
	336	v[XS_WATCH_PATH], xenbus_strstate(backend_state));
	337	wake_up(&backend_state_wq);
	338	}
	339
	340	static void xenbus_reset_wait_for_backend(char *be, int expected)
	341	{
	342	long timeout;
	343	timeout = wait_event_interruptible_timeout(backend_state_wq,
	344	backend_state == expected, 5 * HZ);
	345	if (timeout <= 0)
283c0972	346	pr_info("backend %s timed out\n", be);
116df6f0 OH	347	}
	348
	349	/*
	350	* Reset frontend if it is in Connected or Closed state.
	351	* Wait for backend to catch up.
	352	* State Connected happens during kdump, Closed after kexec.
	353	*/
	354	static void xenbus_reset_frontend(char fe, char be, int be_state)
	355	{
	356	struct xenbus_watch be_watch;
	357
	358	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
	359	be, xenbus_strstate(be_state));
	360
	361	memset(&be_watch, 0, sizeof(be_watch));
	362	be_watch.node = kasprintf(GFP_NOIO \| __GFP_HIGH, "%s/state", be);
	363	if (!be_watch.node)
	364	return;
	365
	366	be_watch.callback = xenbus_reset_backend_state_changed;
	367	backend_state = XenbusStateUnknown;
	368
283c0972	369	pr_info("triggering reconnect on %s\n", be);
116df6f0 OH	370	register_xenbus_watch(&be_watch);
	371
	372	/* fall through to forward backend to state XenbusStateInitialising */
	373	switch (be_state) {
	374	case XenbusStateConnected:
	375	xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
	376	xenbus_reset_wait_for_backend(be, XenbusStateClosing);
	377
	378	case XenbusStateClosing:
	379	xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
	380	xenbus_reset_wait_for_backend(be, XenbusStateClosed);
	381
	382	case XenbusStateClosed:
	383	xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
	384	xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
	385	}
	386
	387	unregister_xenbus_watch(&be_watch);
283c0972	388	pr_info("reconnect done on %s\n", be);
116df6f0 OH	389	kfree(be_watch.node);
	390	}
	391
	392	static void xenbus_check_frontend(char class, char dev)
	393	{
	394	int be_state, fe_state, err;
	395	char backend, frontend;
	396
	397	frontend = kasprintf(GFP_NOIO \| __GFP_HIGH, "device/%s/%s", class, dev);
	398	if (!frontend)
	399	return;
	400
	401	err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
	402	if (err != 1)
	403	goto out;
	404
	405	switch (fe_state) {
	406	case XenbusStateConnected:
	407	case XenbusStateClosed:
	408	printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
	409	frontend, xenbus_strstate(fe_state));
	410	backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
	411	if (!backend \|\| IS_ERR(backend))
	412	goto out;
	413	err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
	414	if (err == 1)
	415	xenbus_reset_frontend(frontend, backend, be_state);
	416	kfree(backend);
	417	break;
	418	default:
	419	break;
	420	}
	421	out:
	422	kfree(frontend);
	423	}
	424
	425	static void xenbus_reset_state(void)
	426	{
	427	char devclass, dev;
	428	int devclass_n, dev_n;
	429	int i, j;
	430
	431	devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
	432	if (IS_ERR(devclass))
	433	return;
	434
	435	for (i = 0; i < devclass_n; i++) {
	436	dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
	437	if (IS_ERR(dev))
	438	continue;
	439	for (j = 0; j < dev_n; j++)
	440	xenbus_check_frontend(devclass[i], dev[j]);
	441	kfree(dev);
	442	}
	443	kfree(devclass);
	444	}
	445
df660251 IC	446	static int frontend_probe_and_watch(struct notifier_block *notifier,
	447	unsigned long event,
	448	void *data)
	449	{
116df6f0 OH	450	/* reset devices in Connected or Closed state */
	451	if (xen_hvm_domain())
	452	xenbus_reset_state();
df660251 IC	453	/* Enumerate devices in xenstore and watch for changes. */
df660251 IC	454	xenbus_probe_devices(&xenbus_frontend);
df660251	455	register_xenbus_watch(&fe_watch);
0ff4fdf0	456
df660251 IC	457	return NOTIFY_DONE;
	458	}
	459
	460
2de06cc1 IC	461	static int __init xenbus_probe_frontend_init(void)
2de06cc1 IC	462	{
df660251 IC	463	static struct notifier_block xenstore_notifier = {
	464	.notifier_call = frontend_probe_and_watch
	465	};
2de06cc1 IC	466	int err;
	467
	468	DPRINTK("");
	469
	470	/* Register ourselves with the kernel bus subsystem */
	471	err = bus_register(&xenbus_frontend.bus);
0ff4fdf0	472	if (err)
2de06cc1	473	return err;
2de06cc1	474
df660251	475	register_xenstore_notifier(&xenstore_notifier);
2de06cc1	476
2abb2746 AC	477	xenbus_frontend_wq = create_workqueue("xenbus_frontend");
2abb2746 AC	478
2de06cc1 IC	479	return 0;
2de06cc1 IC	480	}
806f5463	481	subsys_initcall(xenbus_probe_frontend_init);
2de06cc1 IC	482
	483	#ifndef MODULE
	484	static int __init boot_wait_for_devices(void)
	485	{
	486	if (xen_hvm_domain() && !xen_platform_pci_unplug)
	487	return -ENODEV;
	488
	489	ready_to_wait_for_devices = 1;
	490	wait_for_devices(NULL);
	491	return 0;
	492	}
	493
	494	late_initcall(boot_wait_for_devices);
	495	#endif
1b31a143 JF	496
1b31a143 JF	497	MODULE_LICENSE("GPL");