summaryrefslogtreecommitdiffstats
path: root/drivers/xen/xenbus/xenbus_probe.c
blob: d42e25d5968dcf48acd5448a7a6af56d21abd5fb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
/******************************************************************************
 * Talks to Xen Store to figure out what devices we have.
 *
 * Copyright (C) 2005 Rusty Russell, IBM Corporation
 * Copyright (C) 2005 Mike Wray, Hewlett-Packard
 * Copyright (C) 2005, 2006 XenSource Ltd
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#define DPRINTK(fmt, args...)				\
	pr_debug("xenbus_probe (%s:%d) " fmt ".\n",	\
		 __func__, __LINE__, ##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 <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 "xenbus_comms.h"
#include "xenbus_probe.h"


int xen_store_evtchn;
EXPORT_SYMBOL(xen_store_evtchn);

struct xenstore_domain_interface *xen_store_interface;
static unsigned long xen_store_mfn;

static BLOCKING_NOTIFIER_HEAD(xenstore_chain);

static void wait_for_devices(struct xenbus_driver *xendrv);

static int xenbus_probe_frontend(const char *type, const char *name);

static void xenbus_dev_shutdown(struct device *_dev);

static int xenbus_dev_suspend(struct device *dev, pm_message_t state);
static int xenbus_dev_resume(struct device *dev);

/* If something in array of ids matches this device, return it. */
static const struct xenbus_device_id *
match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
{
	for (; *arr->devicetype != '\0'; arr++) {
		if (!strcmp(arr->devicetype, dev->devicetype))
			return arr;
	}
	return NULL;
}

int xenbus_match(struct device *_dev, struct device_driver *_drv)
{
	struct xenbus_driver *drv = to_xenbus_driver(_drv);

	if (!drv->ids)
		return 0;

	return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
}

static int xenbus_uevent(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;
}

/* 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) {
		printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
		return -EINVAL;
	}

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


static void free_otherend_details(struct xenbus_device *dev)
{
	kfree(dev->otherend);
	dev->otherend = NULL;
}


static void free_otherend_watch(struct xenbus_device *dev)
{
	if (dev->otherend_watch.node) {
		unregister_xenbus_watch(&dev->otherend_watch);
		kfree(dev->otherend_watch.node);
		dev->otherend_watch.node = NULL;
	}
}


int read_otherend_details(struct xenbus_device *xendev,
				 char *id_node, char *path_node)
{
	int err = xenbus_gather(XBT_NIL, xendev->nodename,
				id_node, "%i", &xendev->otherend_id,
				path_node, NULL, &xendev->otherend,
				NULL);
	if (err) {
		xenbus_dev_fatal(xendev, err,
				 "reading other end details from %s",
				 xendev->nodename);
		return err;
	}
	if (strlen(xendev->otherend) == 0 ||
	    !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
		xenbus_dev_fatal(xendev, -ENOENT,
				 "unable to read other end from %s.  "
				 "missing or inaccessible.",
				 xendev->nodename);
		free_otherend_details(xendev);
		return -ENOENT;
	}

	return 0;
}


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

static struct device_attribute xenbus_dev_attrs[] = {
	__ATTR_NULL
};

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

		.suspend   = xenbus_dev_suspend,
		.resume    = xenbus_dev_resume,
	},
};

static void otherend_changed(struct xenbus_watch *watch,
			     const char **vec, unsigned int len)
{
	struct xenbus_device *dev =
		container_of(watch, struct xenbus_device, otherend_watch);
	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
	enum xenbus_state state;

	/* Protect us against watches firing on old details when the otherend
	   details change, say immediately after a resume. */
	if (!dev->otherend ||
	    strncmp(dev->otherend, vec[XS_WATCH_PATH],
		    strlen(dev->otherend))) {
		dev_dbg(&dev->dev, "Ignoring watch at %s\n",
			vec[XS_WATCH_PATH]);
		return;
	}

	state = xenbus_read_driver_state(dev->otherend);

	dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
		state, xenbus_strstate(state), dev->otherend_watch.node,
		vec[XS_WATCH_PATH]);

	/*
	 * Ignore xenbus transitions during shutdown. This prevents us doing
	 * work that can fail e.g., when the rootfs is gone.
	 */
	if (system_state > SYSTEM_RUNNING) {
		struct xen_bus_type *bus = bus;
		bus = container_of(dev->dev.bus, struct xen_bus_type, bus);
		/* If we're frontend, drive the state machine to Closed. */
		/* This should cause the backend to release our resources. */
		if ((bus == &xenbus_frontend) && (state == XenbusStateClosing))
			xenbus_frontend_closed(dev);
		return;
	}

	if (drv->otherend_changed)
		drv->otherend_changed(dev, state);
}


static int talk_to_otherend(struct xenbus_device *dev)
{
	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);

	free_otherend_watch(dev);
	free_otherend_details(dev);

	return drv->read_otherend_details(dev);
}


static int watch_otherend(struct xenbus_device *dev)
{
	return xenbus_watch_pathfmt(dev, &dev->otherend_watch, otherend_changed,
				    "%s/%s", dev->otherend, "state");
}


int xenbus_dev_probe(struct device *_dev)
{
	struct xenbus_device *dev = to_xenbus_device(_dev);
	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
	const struct xenbus_device_id *id;
	int err;

	DPRINTK("%s", dev->nodename);

	if (!drv->probe) {
		err = -ENODEV;
		goto fail;
	}

	id = match_device(drv->ids, dev);
	if (!id) {
		err = -ENODEV;
		goto fail;
	}

	err = talk_to_otherend(dev);
	if (err) {
		dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
			 dev->nodename);
		return err;
	}

	err = drv->probe(dev, id);
	if (err)
		goto fail;

	err = watch_otherend(dev);
	if (err) {
		dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
		       dev->nodename);
		return err;
	}

	return 0;
fail:
	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
	xenbus_switch_state(dev, XenbusStateClosed);
	return -ENODEV;
}

int xenbus_dev_remove(struct device *_dev)
{
	struct xenbus_device *dev = to_xenbus_device(_dev);
	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);

	DPRINTK("%s", dev->nodename);

	free_otherend_watch(dev);
	free_otherend_details(dev);

	if (drv->remove)
		drv->remove(dev);

	xenbus_switch_state(dev, XenbusStateClosed);
	return 0;
}

static void xenbus_dev_shutdown(struct device *_dev)
{
	struct xenbus_device *dev = to_xenbus_device(_dev);
	unsigned long timeout = 5*HZ;

	DPRINTK("%s", dev->nodename);

	get_device(&dev->dev);
	if (dev->state != XenbusStateConnected) {
		printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
		       dev->nodename, xenbus_strstate(dev->state));
		goto out;
	}
	xenbus_switch_state(dev, XenbusStateClosing);
	timeout = wait_for_completion_timeout(&dev->down, timeout);
	if (!timeout)
		printk(KERN_INFO "%s: %s timeout closing device\n",
		       __func__, dev->nodename);
 out:
	put_device(&dev->dev);
}

int xenbus_register_driver_common(struct xenbus_driver *drv,
				  struct xen_bus_type *bus,
				  struct module *owner,
				  const char *mod_name)
{
	drv->driver.name = drv->name;
	drv->driver.bus = &bus->bus;
	drv->driver.owner = owner;
	drv->driver.mod_name = mod_name;

	return driver_register(&drv->driver);
}

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);

void xenbus_unregister_driver(struct xenbus_driver *drv)
{
	driver_unregister(&drv->driver);
}
EXPORT_SYMBOL_GPL(xenbus_unregister_driver);

struct xb_find_info
{
	struct xenbus_device *dev;
	const char *nodename;
};

static int cmp_dev(struct device *dev, void *data)
{
	struct xenbus_device *xendev = to_xenbus_device(dev);
	struct xb_find_info *info = data;

	if (!strcmp(xendev->nodename, info->nodename)) {
		info->dev = xendev;
		get_device(dev);
		return 1;
	}
	return 0;
}

struct xenbus_device *xenbus_device_find(const char *nodename,
					 struct bus_type *bus)
{
	struct xb_find_info info = { .dev = NULL, .nodename = nodename };

	bus_for_each_dev(bus, NULL, &info, cmp_dev);
	return info.dev;
}

static int cleanup_dev(struct device *dev, void *data)
{
	struct xenbus_device *xendev = to_xenbus_device(dev);
	struct xb_find_info *info = data;
	int len = strlen(info->nodename);

	DPRINTK("%s", info->nodename);

	/* Match the info->nodename path, or any subdirectory of that path. */
	if (strncmp(xendev->nodename, info->nodename, len))
		return 0;

	/* If the node name is longer, ensure it really is a subdirectory. */
	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
		return 0;

	info->dev = xendev;
	get_device(dev);
	return 1;
}

static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
{
	struct xb_find_info info = { .nodename = path };

	do {
		info.dev = NULL;
		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
		if (info.dev) {
			device_unregister(&info.dev->dev);
			put_device(&info.dev->dev);
		}
	} while (info.dev);
}

static void xenbus_dev_release(struct device *dev)
{
	if (dev)
		kfree(to_xenbus_device(dev));
}

static ssize_t xendev_show_nodename(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
}
DEVICE_ATTR(nodename, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_nodename, NULL);

static ssize_t xendev_show_devtype(struct device *dev,
				   struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
}
DEVICE_ATTR(devtype, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_devtype, NULL);

static ssize_t xendev_show_modalias(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "xen:%s\n", to_xenbus_device(dev)->devicetype);
}
DEVICE_ATTR(modalias, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_modalias, NULL);

int xenbus_probe_node(struct xen_bus_type *bus,
		      const char *type,
		      const char *nodename)
{
	char devname[XEN_BUS_ID_SIZE];
	int err;
	struct xenbus_device *xendev;
	size_t stringlen;
	char *tmpstring;

	enum xenbus_state state = xenbus_read_driver_state(nodename);

	if (state != XenbusStateInitialising) {
		/* Device is not new, so ignore it.  This can happen if a
		   device is going away after switching to Closed.  */
		return 0;
	}

	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
	if (!xendev)
		return -ENOMEM;

	xendev->state = XenbusStateInitialising;

	/* Copy the strings into the extra space. */

	tmpstring = (char *)(xendev + 1);
	strcpy(tmpstring, nodename);
	xendev->nodename = tmpstring;

	tmpstring += strlen(tmpstring) + 1;
	strcpy(tmpstring, type);
	xendev->devicetype = tmpstring;
	init_completion(&xendev->down);

	xendev->dev.bus = &bus->bus;
	xendev->dev.release = xenbus_dev_release;

	err = bus->get_bus_id(devname, xendev->nodename);
	if (err)
		goto fail;

	dev_set_name(&xendev->dev, devname);

	/* Register with generic device framework. */
	err = device_register(&xendev->dev);
	if (err)
		goto fail;

	err = device_create_file(&xendev->dev, &dev_attr_nodename);
	if (err)
		goto fail_unregister;

	err = device_create_file(&xendev->dev, &dev_attr_devtype);
	if (err)
		goto fail_remove_nodename;

	err = device_create_file(&xendev->dev, &dev_attr_modalias);
	if (err)
		goto fail_remove_devtype;

	return 0;
fail_remove_devtype:
	device_remove_file(&xendev->dev, &dev_attr_devtype);
fail_remove_nodename:
	device_remove_file(&xendev->dev, &dev_attr_nodename);
fail_unregister:
	device_unregister(&xendev->dev);
fail:
	kfree(xendev);
	return err;
}

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

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

	DPRINTK("%s", nodename);

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

static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
{
	int err = 0;
	char **dir;
	unsigned int dir_n = 0;
	int i;

	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
	if (IS_ERR(dir))
		return PTR_ERR(dir);

	for (i = 0; i < dir_n; i++) {
		err = bus->probe(type, dir[i]);
		if (err)
			break;
	}
	kfree(dir);
	return err;
}

int xenbus_probe_devices(struct xen_bus_type *bus)
{
	int err = 0;
	char **dir;
	unsigned int i, dir_n;

	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
	if (IS_ERR(dir))
		return PTR_ERR(dir);

	for (i = 0; i < dir_n; i++) {
		err = xenbus_probe_device_type(bus, dir[i]);
		if (err)
			break;
	}
	kfree(dir);
	return err;
}

static unsigned int char_count(const char *str, char c)
{
	unsigned int i, ret = 0;

	for (i = 0; str[i]; i++)
		if (str[i] == c)
			ret++;
	return ret;
}

static int strsep_len(const char *str, char c, unsigned int len)
{
	unsigned int i;

	for (i = 0; str[i]; i++)
		if (str[i] == c) {
			if (len == 0)
				return i;
			len--;
		}
	return (len == 0) ? i : -ERANGE;
}

void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
{
	int exists, rootlen;
	struct xenbus_device *dev;
	char type[XEN_BUS_ID_SIZE];
	const char *p, *root;

	if (char_count(node, '/') < 2)
		return;

	exists = xenbus_exists(XBT_NIL, node, "");
	if (!exists) {
		xenbus_cleanup_devices(node, &bus->bus);
		return;
	}

	/* backend/<type>/... or device/<type>/... */
	p = strchr(node, '/') + 1;
	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
	type[XEN_BUS_ID_SIZE-1] = '\0';

	rootlen = strsep_len(node, '/', bus->levels);
	if (rootlen < 0)
		return;
	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
	if (!root)
		return;

	dev = xenbus_device_find(root, &bus->bus);
	if (!dev)
		xenbus_probe_node(bus, type, root);
	else
		put_device(&dev->dev);

	kfree(root);
}
EXPORT_SYMBOL_GPL(xenbus_dev_changed);

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 xenbus_dev_suspend(struct device *dev, pm_message_t state)
{
	int err = 0;
	struct xenbus_driver *drv;
	struct xenbus_device *xdev;

	DPRINTK("");

	if (dev->driver == NULL)
		return 0;
	drv = to_xenbus_driver(dev->driver);
	xdev = container_of(dev, struct xenbus_device, dev);
	if (drv->suspend)
		err = drv->suspend(xdev, state);
	if (err)
		printk(KERN_WARNING
		       "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
	return 0;
}

static int xenbus_dev_resume(struct device *dev)
{
	int err;
	struct xenbus_driver *drv;
	struct xenbus_device *xdev;

	DPRINTK("");

	if (dev->driver == NULL)
		return 0;

	drv = to_xenbus_driver(dev->driver);
	xdev = container_of(dev, struct xenbus_device, dev);

	err = talk_to_otherend(xdev);
	if (err) {
		printk(KERN_WARNING
		       "xenbus: resume (talk_to_otherend) %s failed: %i\n",
		       dev_name(dev), err);
		return err;
	}

	xdev->state = XenbusStateInitialising;

	if (drv->resume) {
		err = drv->resume(xdev);
		if (err) {
			printk(KERN_WARNING
			       "xenbus: resume %s failed: %i\n",
			       dev_name(dev), err);
			return err;
		}
	}

	err = watch_otherend(xdev);
	if (err) {
		printk(KERN_WARNING
		       "xenbus_probe: resume (watch_otherend) %s failed: "
		       "%d.\n", dev_name(dev), err);
		return err;
	}

	return 0;
}

/* A flag to determine if xenstored is 'ready' (i.e. has started) */
int xenstored_ready = 0;


int register_xenstore_notifier(struct notifier_block *nb)
{
	int ret = 0;

	if (xenstored_ready > 0)
		ret = nb->notifier_call(nb, 0, NULL);
	else
		blocking_notifier_chain_register(&xenstore_chain, nb);

	return ret;
}
EXPORT_SYMBOL_GPL(register_xenstore_notifier);

void unregister_xenstore_notifier(struct notifier_block *nb)
{
	blocking_notifier_chain_unregister(&xenstore_chain, nb);
}
EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);

void xenbus_probe(struct work_struct *unused)
{
	BUG_ON((xenstored_ready <= 0));

	/* Enumerate devices in xenstore and watch for changes. */
	xenbus_probe_devices(&xenbus_frontend);
	register_xenbus_watch(&fe_watch);
	xenbus_backend_probe_and_watch();

	/* Notify others that xenstore is up */
	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
}

static int __init xenbus_probe_init(void)
{
	int err = 0;

	DPRINTK("");

	err = -ENODEV;
	if (!xen_domain())
		goto out_error;

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

	err = xenbus_backend_bus_register();
	if (err)
		goto out_unreg_front;

	/*
	 * Domain0 doesn't have a store_evtchn or store_mfn yet.
	 */
	if (xen_initial_domain()) {
		/* dom0 not yet supported */
	} else {
		xenstored_ready = 1;
		xen_store_evtchn = xen_start_info->store_evtchn;
		xen_store_mfn = xen_start_info->store_mfn;
	}
	xen_store_interface = mfn_to_virt(xen_store_mfn);

	/* Initialize the interface to xenstore. */
	err = xs_init();
	if (err) {
		printk(KERN_WARNING
		       "XENBUS: Error initializing xenstore comms: %i\n", err);
		goto out_unreg_back;
	}

	if (!xen_initial_domain())
		xenbus_probe(NULL);

#ifdef CONFIG_XEN_COMPAT_XENFS
	/*
	 * Create xenfs mountpoint in /proc for compatibility with
	 * utilities that expect to find "xenbus" under "/proc/xen".
	 */
	proc_mkdir("xen", NULL);
#endif

	return 0;

  out_unreg_back:
	xenbus_backend_bus_unregister();

  out_unreg_front:
	bus_unregister(&xenbus_frontend.bus);

  out_error:
	return err;
}

postcore_initcall(xenbus_probe_init);

MODULE_LICENSE("GPL");

static int is_disconnected_device(struct device *dev, void *data)
{
	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;

	xendrv = to_xenbus_driver(dev->driver);
	return (xendev->state != XenbusStateConnected ||
		(xendrv->is_ready && !xendrv->is_ready(xendev)));
}

static int exists_disconnected_device(struct device_driver *drv)
{
	return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
				is_disconnected_device);
}

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? */
		printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
		       xendev->nodename);
	} else if (xendev->state != XenbusStateConnected) {
		printk(KERN_WARNING "XENBUS: Timeout connecting "
		       "to device: %s (state %d)\n",
		       xendev->nodename, xendev->state);
	}

	return 0;
}

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

/*
 * On a 10 second 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 timeout = jiffies + 10*HZ;
	struct device_driver *drv = xendrv ? &xendrv->driver : NULL;

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

	while (exists_disconnected_device(drv)) {
		if (time_after(jiffies, timeout))
			break;
		schedule_timeout_interruptible(HZ/10);
	}

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

#ifndef MODULE
static int __init boot_wait_for_devices(void)
{
	ready_to_wait_for_devices = 1;
	wait_for_devices(NULL);
	return 0;
}

late_initcall(boot_wait_for_devices);
#endif
OpenPOWER on IntegriCloud