[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;
		}

		queue_work(xenbus_frontend_wq, &xdev->work);

		return 0;
	}

	return xenbus_dev_resume(dev);
}

static int xenbus_frontend_dev_probe(struct device *dev)
{
	if (xen_store_domain_type == XS_LOCAL) {
		struct xenbus_device *xdev = to_xenbus_device(dev);
		INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume);
	}

	return xenbus_dev_probe(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_frontend_dev_probe,
		.remove		= xenbus_dev_remove,
		.shutdown	= xenbus_dev_shutdown,
		.dev_groups	= xenbus_dev_groups,

		.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, struct module *owner,
			       const char *mod_name)
{
	int ret;

	drv->read_otherend_details = read_backend_details;

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

	if (xen_store_domain_type == XS_LOCAL) {
		xenbus_frontend_wq = create_workqueue("xenbus_frontend");
		if (!xenbus_frontend_wq)
			pr_warn("create xenbus frontend workqueue failed, S3 resume is likely to fail\n");
	}

	return 0;
}
subsys_initcall(xenbus_probe_frontend_init);

#ifndef MODULE
static int __init boot_wait_for_devices(void)
{
	if (!xen_has_pv_devices())
		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
2abb2746 AC	118	queue_work(xenbus_frontend_wq, &xdev->work);
	119
	120	return 0;
	121	}
	122
	123	return xenbus_dev_resume(dev);
	124	}
	125
d7ead0c3 AC	126	static int xenbus_frontend_dev_probe(struct device *dev)
	127	{
	128	if (xen_store_domain_type == XS_LOCAL) {
	129	struct xenbus_device *xdev = to_xenbus_device(dev);
	130	INIT_WORK(&xdev->work, xenbus_frontend_delayed_resume);
	131	}
	132
	133	return xenbus_dev_probe(dev);
	134	}
	135
c7853aea	136	static const struct dev_pm_ops xenbus_pm_ops = {
b3e96c0c	137	.suspend = xenbus_dev_suspend,
2abb2746	138	.resume = xenbus_frontend_dev_resume,
b3e96c0c SR	139	.freeze = xenbus_dev_suspend,
	140	.thaw = xenbus_dev_cancel,
	141	.restore = xenbus_dev_resume,
c7853aea KS	142	};
c7853aea KS	143
2de06cc1 IC	144	static struct xen_bus_type xenbus_frontend = {
2de06cc1 IC	145	.root = "device",
6bac7f9f	146	.levels = 2, /* device/type/<id> */
2de06cc1 IC	147	.get_bus_id = frontend_bus_id,
	148	.probe = xenbus_probe_frontend,
	149	.otherend_changed = backend_changed,
	150	.bus = {
6bac7f9f IC	151	.name = "xen",
	152	.match = xenbus_match,
	153	.uevent = xenbus_uevent_frontend,
d7ead0c3	154	.probe = xenbus_frontend_dev_probe,
6bac7f9f IC	155	.remove = xenbus_dev_remove,
6bac7f9f IC	156	.shutdown = xenbus_dev_shutdown,
85dd9268	157	.dev_groups = xenbus_dev_groups,
6bac7f9f	158
c7853aea	159	.pm = &xenbus_pm_ops,
2de06cc1 IC	160	},
	161	};
	162
	163	static void frontend_changed(struct xenbus_watch *watch,
	164	const char **vec, unsigned int len)
	165	{
	166	DPRINTK("");
	167
	168	xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
	169	}
	170
	171
	172	/* We watch for devices appearing and vanishing. */
	173	static struct xenbus_watch fe_watch = {
	174	.node = "device",
	175	.callback = frontend_changed,
	176	};
	177
	178	static int read_backend_details(struct xenbus_device *xendev)
	179	{
	180	return xenbus_read_otherend_details(xendev, "backend-id", "backend");
	181	}
	182
3066616c	183	static int is_device_connecting(struct device dev, void data, bool ignore_nonessential)
2de06cc1 IC	184	{
	185	struct xenbus_device *xendev = to_xenbus_device(dev);
	186	struct device_driver *drv = data;
	187	struct xenbus_driver *xendrv;
	188
	189	/*
	190	* A device with no driver will never connect. We care only about
	191	* devices which should currently be in the process of connecting.
	192	*/
	193	if (!dev->driver)
	194	return 0;
	195
	196	/* Is this search limited to a particular driver? */
	197	if (drv && (dev->driver != drv))
	198	return 0;
	199
3066616c KRW	200	if (ignore_nonessential) {
	201	/* With older QEMU, for PVonHVM guests the guest config files
	202	* could contain: vfb = [ 'vnc=1, vnclisten=0.0.0.0']
	203	* which is nonsensical as there is no PV FB (there can be
	204	* a PVKB) running as HVM guest. */
	205
	206	if ((strncmp(xendev->nodename, "device/vkbd", 11) == 0))
	207	return 0;
	208
	209	if ((strncmp(xendev->nodename, "device/vfb", 10) == 0))
	210	return 0;
	211	}
2de06cc1 IC	212	xendrv = to_xenbus_driver(dev->driver);
	213	return (xendev->state < XenbusStateConnected \|\|
	214	(xendev->state == XenbusStateConnected &&
	215	xendrv->is_ready && !xendrv->is_ready(xendev)));
	216	}
3066616c KRW	217	static int essential_device_connecting(struct device dev, void data)
	218	{
	219	return is_device_connecting(dev, data, true /* ignore PV[KBB+FB] */);
	220	}
	221	static int non_essential_device_connecting(struct device dev, void data)
	222	{
	223	return is_device_connecting(dev, data, false);
	224	}
2de06cc1	225
3066616c	226	static int exists_essential_connecting_device(struct device_driver *drv)
2de06cc1 IC	227	{
2de06cc1 IC	228	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
3066616c KRW	229	essential_device_connecting);
	230	}
	231	static int exists_non_essential_connecting_device(struct device_driver *drv)
	232	{
	233	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
	234	non_essential_device_connecting);
2de06cc1 IC	235	}
	236
	237	static int print_device_status(struct device dev, void data)
	238	{
	239	struct xenbus_device *xendev = to_xenbus_device(dev);
	240	struct device_driver *drv = data;
	241
	242	/* Is this operation limited to a particular driver? */
	243	if (drv && (dev->driver != drv))
	244	return 0;
	245
	246	if (!dev->driver) {
	247	/* Information only: is this too noisy? */
283c0972	248	pr_info("Device with no driver: %s\n", xendev->nodename);
2de06cc1 IC	249	} else if (xendev->state < XenbusStateConnected) {
	250	enum xenbus_state rstate = XenbusStateUnknown;
	251	if (xendev->otherend)
	252	rstate = xenbus_read_driver_state(xendev->otherend);
283c0972 JP	253	pr_warn("Timeout connecting to device: %s (local state %d, remote state %d)\n",
283c0972 JP	254	xendev->nodename, xendev->state, rstate);
2de06cc1 IC	255	}
	256
	257	return 0;
	258	}
	259
	260	/* We only wait for device setup after most initcalls have run. */
	261	static int ready_to_wait_for_devices;
	262
3066616c KRW	263	static bool wait_loop(unsigned long start, unsigned int max_delay,
	264	unsigned int *seconds_waited)
	265	{
	266	if (time_after(jiffies, start + (seconds_waited+5)HZ)) {
	267	if (!*seconds_waited)
283c0972	268	pr_warn("Waiting for devices to initialise: ");
3066616c	269	*seconds_waited += 5;
283c0972 JP	270	pr_cont("%us...", max_delay - *seconds_waited);
	271	if (*seconds_waited == max_delay) {
	272	pr_cont("\n");
3066616c	273	return true;
283c0972	274	}
3066616c KRW	275	}
	276
	277	schedule_timeout_interruptible(HZ/10);
	278
	279	return false;
	280	}
2de06cc1 IC	281	/*
	282	* On a 5-minute timeout, wait for all devices currently configured. We need
	283	* to do this to guarantee that the filesystems and / or network devices
	284	* needed for boot are available, before we can allow the boot to proceed.
	285	*
	286	* This needs to be on a late_initcall, to happen after the frontend device
	287	* drivers have been initialised, but before the root fs is mounted.
	288	*
	289	* A possible improvement here would be to have the tools add a per-device
	290	* flag to the store entry, indicating whether it is needed at boot time.
	291	* This would allow people who knew what they were doing to accelerate their
	292	* boot slightly, but of course needs tools or manual intervention to set up
	293	* those flags correctly.
	294	*/
	295	static void wait_for_devices(struct xenbus_driver *xendrv)
	296	{
	297	unsigned long start = jiffies;
	298	struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
	299	unsigned int seconds_waited = 0;
	300
	301	if (!ready_to_wait_for_devices \|\| !xen_domain())
	302	return;
	303
3066616c KRW	304	while (exists_non_essential_connecting_device(drv))
	305	if (wait_loop(start, 30, &seconds_waited))
	306	break;
	307
	308	/* Skips PVKB and PVFB check.*/
	309	while (exists_essential_connecting_device(drv))
	310	if (wait_loop(start, 270, &seconds_waited))
	311	break;
2de06cc1 IC	312
	313	if (seconds_waited)
	314	printk("\n");
	315
	316	bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
	317	print_device_status);
	318	}
	319
95afae48 DV	320	int __xenbus_register_frontend(struct xenbus_driver drv, struct module owner,
95afae48 DV	321	const char *mod_name)
2de06cc1 IC	322	{
	323	int ret;
	324
	325	drv->read_otherend_details = read_backend_details;
	326
95afae48 DV	327	ret = xenbus_register_driver_common(drv, &xenbus_frontend,
95afae48 DV	328	owner, mod_name);
2de06cc1 IC	329	if (ret)
	330	return ret;
	331
	332	/* If this driver is loaded as a module wait for devices to attach. */
	333	wait_for_devices(drv);
	334
	335	return 0;
	336	}
95afae48	337	EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
2de06cc1	338
116df6f0 OH	339	static DECLARE_WAIT_QUEUE_HEAD(backend_state_wq);
	340	static int backend_state;
	341
	342	static void xenbus_reset_backend_state_changed(struct xenbus_watch *w,
	343	const char **v, unsigned int l)
	344	{
	345	xenbus_scanf(XBT_NIL, v[XS_WATCH_PATH], "", "%i", &backend_state);
	346	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
	347	v[XS_WATCH_PATH], xenbus_strstate(backend_state));
	348	wake_up(&backend_state_wq);
	349	}
	350
	351	static void xenbus_reset_wait_for_backend(char *be, int expected)
	352	{
	353	long timeout;
	354	timeout = wait_event_interruptible_timeout(backend_state_wq,
	355	backend_state == expected, 5 * HZ);
	356	if (timeout <= 0)
283c0972	357	pr_info("backend %s timed out\n", be);
116df6f0 OH	358	}
	359
	360	/*
	361	* Reset frontend if it is in Connected or Closed state.
	362	* Wait for backend to catch up.
	363	* State Connected happens during kdump, Closed after kexec.
	364	*/
	365	static void xenbus_reset_frontend(char fe, char be, int be_state)
	366	{
	367	struct xenbus_watch be_watch;
	368
	369	printk(KERN_DEBUG "XENBUS: backend %s %s\n",
	370	be, xenbus_strstate(be_state));
	371
	372	memset(&be_watch, 0, sizeof(be_watch));
	373	be_watch.node = kasprintf(GFP_NOIO \| __GFP_HIGH, "%s/state", be);
	374	if (!be_watch.node)
	375	return;
	376
	377	be_watch.callback = xenbus_reset_backend_state_changed;
	378	backend_state = XenbusStateUnknown;
	379
283c0972	380	pr_info("triggering reconnect on %s\n", be);
116df6f0 OH	381	register_xenbus_watch(&be_watch);
	382
	383	/* fall through to forward backend to state XenbusStateInitialising */
	384	switch (be_state) {
	385	case XenbusStateConnected:
	386	xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosing);
	387	xenbus_reset_wait_for_backend(be, XenbusStateClosing);
	388
	389	case XenbusStateClosing:
	390	xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateClosed);
	391	xenbus_reset_wait_for_backend(be, XenbusStateClosed);
	392
	393	case XenbusStateClosed:
	394	xenbus_printf(XBT_NIL, fe, "state", "%d", XenbusStateInitialising);
	395	xenbus_reset_wait_for_backend(be, XenbusStateInitWait);
	396	}
	397
	398	unregister_xenbus_watch(&be_watch);
283c0972	399	pr_info("reconnect done on %s\n", be);
116df6f0 OH	400	kfree(be_watch.node);
	401	}
	402
	403	static void xenbus_check_frontend(char class, char dev)
	404	{
	405	int be_state, fe_state, err;
	406	char backend, frontend;
	407
	408	frontend = kasprintf(GFP_NOIO \| __GFP_HIGH, "device/%s/%s", class, dev);
	409	if (!frontend)
	410	return;
	411
	412	err = xenbus_scanf(XBT_NIL, frontend, "state", "%i", &fe_state);
	413	if (err != 1)
	414	goto out;
	415
	416	switch (fe_state) {
	417	case XenbusStateConnected:
	418	case XenbusStateClosed:
	419	printk(KERN_DEBUG "XENBUS: frontend %s %s\n",
	420	frontend, xenbus_strstate(fe_state));
	421	backend = xenbus_read(XBT_NIL, frontend, "backend", NULL);
	422	if (!backend \|\| IS_ERR(backend))
	423	goto out;
	424	err = xenbus_scanf(XBT_NIL, backend, "state", "%i", &be_state);
	425	if (err == 1)
	426	xenbus_reset_frontend(frontend, backend, be_state);
	427	kfree(backend);
	428	break;
	429	default:
	430	break;
	431	}
	432	out:
	433	kfree(frontend);
	434	}
	435
	436	static void xenbus_reset_state(void)
	437	{
	438	char devclass, dev;
	439	int devclass_n, dev_n;
	440	int i, j;
	441
	442	devclass = xenbus_directory(XBT_NIL, "device", "", &devclass_n);
	443	if (IS_ERR(devclass))
	444	return;
	445
	446	for (i = 0; i < devclass_n; i++) {
	447	dev = xenbus_directory(XBT_NIL, "device", devclass[i], &dev_n);
	448	if (IS_ERR(dev))
	449	continue;
	450	for (j = 0; j < dev_n; j++)
	451	xenbus_check_frontend(devclass[i], dev[j]);
	452	kfree(dev);
	453	}
	454	kfree(devclass);
	455	}
	456
df660251 IC	457	static int frontend_probe_and_watch(struct notifier_block *notifier,
	458	unsigned long event,
	459	void *data)
	460	{
116df6f0 OH	461	/* reset devices in Connected or Closed state */
	462	if (xen_hvm_domain())
	463	xenbus_reset_state();
df660251 IC	464	/* Enumerate devices in xenstore and watch for changes. */
df660251 IC	465	xenbus_probe_devices(&xenbus_frontend);
df660251	466	register_xenbus_watch(&fe_watch);
0ff4fdf0	467
df660251 IC	468	return NOTIFY_DONE;
	469	}
	470
	471
2de06cc1 IC	472	static int __init xenbus_probe_frontend_init(void)
2de06cc1 IC	473	{
df660251 IC	474	static struct notifier_block xenstore_notifier = {
	475	.notifier_call = frontend_probe_and_watch
	476	};
2de06cc1 IC	477	int err;
	478
	479	DPRINTK("");
	480
	481	/* Register ourselves with the kernel bus subsystem */
	482	err = bus_register(&xenbus_frontend.bus);
0ff4fdf0	483	if (err)
2de06cc1	484	return err;
2de06cc1	485
df660251	486	register_xenstore_notifier(&xenstore_notifier);
2de06cc1	487
d7ead0c3 AC	488	if (xen_store_domain_type == XS_LOCAL) {
	489	xenbus_frontend_wq = create_workqueue("xenbus_frontend");
	490	if (!xenbus_frontend_wq)
	491	pr_warn("create xenbus frontend workqueue failed, S3 resume is likely to fail\n");
	492	}
2abb2746	493
2de06cc1 IC	494	return 0;
2de06cc1 IC	495	}
806f5463	496	subsys_initcall(xenbus_probe_frontend_init);
2de06cc1 IC	497
	498	#ifndef MODULE
	499	static int __init boot_wait_for_devices(void)
	500	{
51c71a3b	501	if (!xen_has_pv_devices())
2de06cc1 IC	502	return -ENODEV;
	503
	504	ready_to_wait_for_devices = 1;
	505	wait_for_devices(NULL);
	506	return 0;
	507	}
	508
	509	late_initcall(boot_wait_for_devices);
	510	#endif
1b31a143 JF	511
1b31a143 JF	512	MODULE_LICENSE("GPL");