summaryrefslogtreecommitdiffstats
path: root/lib/kobject.c
blob: 4572809d1b959d416fa8b5857e78741e32ca6c24 (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
/*
 * kobject.c - library routines for handling generic kernel objects
 *
 * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>
 *
 * This file is released under the GPLv2.
 *
 *
 * Please see the file Documentation/kobject.txt for critical information
 * about using the kobject interface.
 */

#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/module.h>
#include <linux/stat.h>
#include <linux/slab.h>

/**
 *	populate_dir - populate directory with attributes.
 *	@kobj:	object we're working on.
 *
 *	Most subsystems have a set of default attributes that 
 *	are associated with an object that registers with them.
 *	This is a helper called during object registration that 
 *	loops through the default attributes of the subsystem 
 *	and creates attributes files for them in sysfs.
 *
 */

static int populate_dir(struct kobject * kobj)
{
	struct kobj_type * t = get_ktype(kobj);
	struct attribute * attr;
	int error = 0;
	int i;
	
	if (t && t->default_attrs) {
		for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
			if ((error = sysfs_create_file(kobj,attr)))
				break;
		}
	}
	return error;
}

static int create_dir(struct kobject * kobj, struct dentry *shadow_parent)
{
	int error = 0;
	if (kobject_name(kobj)) {
		error = sysfs_create_dir(kobj, shadow_parent);
		if (!error) {
			if ((error = populate_dir(kobj)))
				sysfs_remove_dir(kobj);
		}
	}
	return error;
}

static inline struct kobject * to_kobj(struct list_head * entry)
{
	return container_of(entry,struct kobject,entry);
}

static int get_kobj_path_length(struct kobject *kobj)
{
	int length = 1;
	struct kobject * parent = kobj;

	/* walk up the ancestors until we hit the one pointing to the 
	 * root.
	 * Add 1 to strlen for leading '/' of each level.
	 */
	do {
		if (kobject_name(parent) == NULL)
			return 0;
		length += strlen(kobject_name(parent)) + 1;
		parent = parent->parent;
	} while (parent);
	return length;
}

static void fill_kobj_path(struct kobject *kobj, char *path, int length)
{
	struct kobject * parent;

	--length;
	for (parent = kobj; parent; parent = parent->parent) {
		int cur = strlen(kobject_name(parent));
		/* back up enough to print this name with '/' */
		length -= cur;
		strncpy (path + length, kobject_name(parent), cur);
		*(path + --length) = '/';
	}

	pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
}

/**
 * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
 *
 * @kobj:	kobject in question, with which to build the path
 * @gfp_mask:	the allocation type used to allocate the path
 *
 * The result must be freed by the caller with kfree().
 */
char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
{
	char *path;
	int len;

	len = get_kobj_path_length(kobj);
	if (len == 0)
		return NULL;
	path = kzalloc(len, gfp_mask);
	if (!path)
		return NULL;
	fill_kobj_path(kobj, path, len);

	return path;
}
EXPORT_SYMBOL_GPL(kobject_get_path);

/**
 *	kobject_init - initialize object.
 *	@kobj:	object in question.
 */
void kobject_init(struct kobject * kobj)
{
	if (!kobj)
		return;
	kref_init(&kobj->kref);
	INIT_LIST_HEAD(&kobj->entry);
	init_waitqueue_head(&kobj->poll);
	kobj->kset = kset_get(kobj->kset);
}


/**
 *	unlink - remove kobject from kset list.
 *	@kobj:	kobject.
 *
 *	Remove the kobject from the kset list and decrement
 *	its parent's refcount.
 *	This is separated out, so we can use it in both 
 *	kobject_del() and kobject_add() on error.
 */

static void unlink(struct kobject * kobj)
{
	if (kobj->kset) {
		spin_lock(&kobj->kset->list_lock);
		list_del_init(&kobj->entry);
		spin_unlock(&kobj->kset->list_lock);
	}
	kobject_put(kobj);
}

/**
 *	kobject_add - add an object to the hierarchy.
 *	@kobj:	object.
 *	@shadow_parent: sysfs directory to add to.
 */

int kobject_shadow_add(struct kobject * kobj, struct dentry *shadow_parent)
{
	int error = 0;
	struct kobject * parent;

	if (!(kobj = kobject_get(kobj)))
		return -ENOENT;
	if (!kobj->k_name)
		kobj->k_name = kobj->name;
	if (!kobj->k_name) {
		pr_debug("kobject attempted to be registered with no name!\n");
		WARN_ON(1);
		return -EINVAL;
	}
	parent = kobject_get(kobj->parent);

	pr_debug("kobject %s: registering. parent: %s, set: %s\n",
		 kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>", 
		 kobj->kset ? kobj->kset->kobj.name : "<NULL>" );

	if (kobj->kset) {
		spin_lock(&kobj->kset->list_lock);

		if (!parent)
			parent = kobject_get(&kobj->kset->kobj);

		list_add_tail(&kobj->entry,&kobj->kset->list);
		spin_unlock(&kobj->kset->list_lock);
	}
	kobj->parent = parent;

	error = create_dir(kobj, shadow_parent);
	if (error) {
		/* unlink does the kobject_put() for us */
		unlink(kobj);
		kobject_put(parent);

		/* be noisy on error issues */
		if (error == -EEXIST)
			printk("kobject_add failed for %s with -EEXIST, "
			       "don't try to register things with the "
			       "same name in the same directory.\n",
			       kobject_name(kobj));
		else
			printk("kobject_add failed for %s (%d)\n",
			       kobject_name(kobj), error);
		 dump_stack();
	}

	return error;
}

/**
 *	kobject_add - add an object to the hierarchy.
 *	@kobj:	object.
 */
int kobject_add(struct kobject * kobj)
{
	return kobject_shadow_add(kobj, NULL);
}


/**
 *	kobject_register - initialize and add an object.
 *	@kobj:	object in question.
 */

int kobject_register(struct kobject * kobj)
{
	int error = -EINVAL;
	if (kobj) {
		kobject_init(kobj);
		error = kobject_add(kobj);
		if (!error)
			kobject_uevent(kobj, KOBJ_ADD);
	}
	return error;
}


/**
 *	kobject_set_name - Set the name of an object
 *	@kobj:	object.
 *	@fmt:	format string used to build the name
 *
 *	If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
 *	string that @kobj->k_name points to. Otherwise, use the static 
 *	@kobj->name array.
 */
int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
{
	int error = 0;
	int limit = KOBJ_NAME_LEN;
	int need;
	va_list args;
	char * name;

	/* 
	 * First, try the static array 
	 */
	va_start(args,fmt);
	need = vsnprintf(kobj->name,limit,fmt,args);
	va_end(args);
	if (need < limit) 
		name = kobj->name;
	else {
		/* 
		 * Need more space? Allocate it and try again 
		 */
		limit = need + 1;
		name = kmalloc(limit,GFP_KERNEL);
		if (!name) {
			error = -ENOMEM;
			goto Done;
		}
		va_start(args,fmt);
		need = vsnprintf(name,limit,fmt,args);
		va_end(args);

		/* Still? Give up. */
		if (need >= limit) {
			kfree(name);
			error = -EFAULT;
			goto Done;
		}
	}

	/* Free the old name, if necessary. */
	if (kobj->k_name && kobj->k_name != kobj->name)
		kfree(kobj->k_name);

	/* Now, set the new name */
	kobj->k_name = name;
 Done:
	return error;
}

EXPORT_SYMBOL(kobject_set_name);


/**
 *	kobject_rename - change the name of an object
 *	@kobj:	object in question.
 *	@new_name: object's new name
 */

int kobject_rename(struct kobject * kobj, const char *new_name)
{
	int error = 0;

	kobj = kobject_get(kobj);
	if (!kobj)
		return -EINVAL;
	if (!kobj->parent)
		return -EINVAL;
	error = sysfs_rename_dir(kobj, kobj->parent->dentry, new_name);
	kobject_put(kobj);

	return error;
}

/**
 *	kobject_rename - change the name of an object
 *	@kobj:	object in question.
 *	@new_parent: object's new parent
 *	@new_name: object's new name
 */

int kobject_shadow_rename(struct kobject * kobj, struct dentry *new_parent,
			  const char *new_name)
{
	int error = 0;

	kobj = kobject_get(kobj);
	if (!kobj)
		return -EINVAL;
	error = sysfs_rename_dir(kobj, new_parent, new_name);
	kobject_put(kobj);

	return error;
}

/**
 *	kobject_move - move object to another parent
 *	@kobj:	object in question.
 *	@new_parent: object's new parent (can be NULL)
 */

int kobject_move(struct kobject *kobj, struct kobject *new_parent)
{
	int error;
	struct kobject *old_parent;
	const char *devpath = NULL;
	char *devpath_string = NULL;
	char *envp[2];

	kobj = kobject_get(kobj);
	if (!kobj)
		return -EINVAL;
	new_parent = kobject_get(new_parent);
	if (!new_parent) {
		if (kobj->kset)
			new_parent = kobject_get(&kobj->kset->kobj);
	}
	/* old object path */
	devpath = kobject_get_path(kobj, GFP_KERNEL);
	if (!devpath) {
		error = -ENOMEM;
		goto out;
	}
	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
	if (!devpath_string) {
		error = -ENOMEM;
		goto out;
	}
	sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
	envp[0] = devpath_string;
	envp[1] = NULL;
	error = sysfs_move_dir(kobj, new_parent);
	if (error)
		goto out;
	old_parent = kobj->parent;
	kobj->parent = new_parent;
	kobject_put(old_parent);
	kobject_uevent_env(kobj, KOBJ_MOVE, envp);
out:
	kobject_put(kobj);
	kfree(devpath_string);
	kfree(devpath);
	return error;
}

/**
 *	kobject_del - unlink kobject from hierarchy.
 * 	@kobj:	object.
 */

void kobject_del(struct kobject * kobj)
{
	if (!kobj)
		return;
	sysfs_remove_dir(kobj);
	unlink(kobj);
}

/**
 *	kobject_unregister - remove object from hierarchy and decrement refcount.
 *	@kobj:	object going away.
 */

void kobject_unregister(struct kobject * kobj)
{
	if (!kobj)
		return;
	pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
	kobject_uevent(kobj, KOBJ_REMOVE);
	kobject_del(kobj);
	kobject_put(kobj);
}

/**
 *	kobject_get - increment refcount for object.
 *	@kobj:	object.
 */

struct kobject * kobject_get(struct kobject * kobj)
{
	if (kobj)
		kref_get(&kobj->kref);
	return kobj;
}

/**
 *	kobject_cleanup - free kobject resources. 
 *	@kobj:	object.
 */

void kobject_cleanup(struct kobject * kobj)
{
	struct kobj_type * t = get_ktype(kobj);
	struct kset * s = kobj->kset;
	struct kobject * parent = kobj->parent;

	pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
	if (kobj->k_name != kobj->name)
		kfree(kobj->k_name);
	kobj->k_name = NULL;
	if (t && t->release)
		t->release(kobj);
	if (s)
		kset_put(s);
	kobject_put(parent);
}

static void kobject_release(struct kref *kref)
{
	kobject_cleanup(container_of(kref, struct kobject, kref));
}

/**
 *	kobject_put - decrement refcount for object.
 *	@kobj:	object.
 *
 *	Decrement the refcount, and if 0, call kobject_cleanup().
 */
void kobject_put(struct kobject * kobj)
{
	if (kobj)
		kref_put(&kobj->kref, kobject_release);
}


static void dir_release(struct kobject *kobj)
{
	kfree(kobj);
}

static struct kobj_type dir_ktype = {
	.release	= dir_release,
	.sysfs_ops	= NULL,
	.default_attrs	= NULL,
};

/**
 *	kobject_add_dir - add sub directory of object.
 *	@parent:	object in which a directory is created.
 *	@name:	directory name.
 *
 *	Add a plain directory object as child of given object.
 */
struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
{
	struct kobject *k;
	int ret;

	if (!parent)
		return NULL;

	k = kzalloc(sizeof(*k), GFP_KERNEL);
	if (!k)
		return NULL;

	k->parent = parent;
	k->ktype = &dir_ktype;
	kobject_set_name(k, name);
	ret = kobject_register(k);
	if (ret < 0) {
		printk(KERN_WARNING "kobject_add_dir: "
			"kobject_register error: %d\n", ret);
		kobject_del(k);
		return NULL;
	}

	return k;
}

/**
 *	kset_init - initialize a kset for use
 *	@k:	kset 
 */

void kset_init(struct kset * k)
{
	kobject_init(&k->kobj);
	INIT_LIST_HEAD(&k->list);
	spin_lock_init(&k->list_lock);
}


/**
 *	kset_add - add a kset object to the hierarchy.
 *	@k:	kset.
 *
 *	Simply, this adds the kset's embedded kobject to the 
 *	hierarchy. 
 *	We also try to make sure that the kset's embedded kobject
 *	has a parent before it is added. We only care if the embedded
 *	kobject is not part of a kset itself, since kobject_add()
 *	assigns a parent in that case. 
 *	If that is the case, and the kset has a controlling subsystem,
 *	then we set the kset's parent to be said subsystem. 
 */

int kset_add(struct kset * k)
{
	if (!k->kobj.parent && !k->kobj.kset && k->subsys)
		k->kobj.parent = &k->subsys->kset.kobj;

	return kobject_add(&k->kobj);
}


/**
 *	kset_register - initialize and add a kset.
 *	@k:	kset.
 */

int kset_register(struct kset * k)
{
	if (!k)
		return -EINVAL;
	kset_init(k);
	return kset_add(k);
}


/**
 *	kset_unregister - remove a kset.
 *	@k:	kset.
 */

void kset_unregister(struct kset * k)
{
	if (!k)
		return;
	kobject_unregister(&k->kobj);
}


/**
 *	kset_find_obj - search for object in kset.
 *	@kset:	kset we're looking in.
 *	@name:	object's name.
 *
 *	Lock kset via @kset->subsys, and iterate over @kset->list,
 *	looking for a matching kobject. If matching object is found
 *	take a reference and return the object.
 */

struct kobject * kset_find_obj(struct kset * kset, const char * name)
{
	struct list_head * entry;
	struct kobject * ret = NULL;

	spin_lock(&kset->list_lock);
	list_for_each(entry,&kset->list) {
		struct kobject * k = to_kobj(entry);
		if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
			ret = kobject_get(k);
			break;
		}
	}
	spin_unlock(&kset->list_lock);
	return ret;
}


void subsystem_init(struct subsystem * s)
{
	init_rwsem(&s->rwsem);
	kset_init(&s->kset);
}

/**
 *	subsystem_register - register a subsystem.
 *	@s:	the subsystem we're registering.
 *
 *	Once we register the subsystem, we want to make sure that 
 *	the kset points back to this subsystem for correct usage of 
 *	the rwsem. 
 */

int subsystem_register(struct subsystem * s)
{
	int error;

	if (!s)
		return -EINVAL;

	subsystem_init(s);
	pr_debug("subsystem %s: registering\n",s->kset.kobj.name);

	if (!(error = kset_add(&s->kset))) {
		if (!s->kset.subsys)
			s->kset.subsys = s;
	}
	return error;
}

void subsystem_unregister(struct subsystem * s)
{
	if (!s)
		return;
	pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
	kset_unregister(&s->kset);
}


/**
 *	subsystem_create_file - export sysfs attribute file.
 *	@s:	subsystem.
 *	@a:	subsystem attribute descriptor.
 */

int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
{
	int error = 0;

	if (!s || !a)
		return -EINVAL;

	if (subsys_get(s)) {
		error = sysfs_create_file(&s->kset.kobj,&a->attr);
		subsys_put(s);
	}
	return error;
}


/**
 *	subsystem_remove_file - remove sysfs attribute file.
 *	@s:	subsystem.
 *	@a:	attribute desciptor.
 */
#if 0
void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
{
	if (subsys_get(s)) {
		sysfs_remove_file(&s->kset.kobj,&a->attr);
		subsys_put(s);
	}
}
#endif  /*  0  */

EXPORT_SYMBOL(kobject_init);
EXPORT_SYMBOL(kobject_register);
EXPORT_SYMBOL(kobject_unregister);
EXPORT_SYMBOL(kobject_get);
EXPORT_SYMBOL(kobject_put);
EXPORT_SYMBOL(kobject_add);
EXPORT_SYMBOL(kobject_del);

EXPORT_SYMBOL(kset_register);
EXPORT_SYMBOL(kset_unregister);

EXPORT_SYMBOL(subsystem_register);
EXPORT_SYMBOL(subsystem_unregister);
EXPORT_SYMBOL(subsys_create_file);
OpenPOWER on IntegriCloud