summaryrefslogtreecommitdiff
path: root/sound/core/info.c
blob: 8c6bc5241df50c55a66c35a8b4e9d8863664d5af (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Information interface for ALSA driver
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#include <linux/init.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/info.h>
#include <linux/utsname.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
#include <stdarg.h>

int snd_info_check_reserved_words(const char *str)
{
	static const char * const reserved[] =
	{
		"version",
		"meminfo",
		"memdebug",
		"detect",
		"devices",
		"oss",
		"cards",
		"timers",
		"synth",
		"pcm",
		"seq",
		NULL
	};
	const char * const *xstr = reserved;

	while (*xstr) {
		if (!strcmp(*xstr, str))
			return 0;
		xstr++;
	}
	if (!strncmp(str, "card", 4))
		return 0;
	return 1;
}

static DEFINE_MUTEX(info_mutex);

struct snd_info_private_data {
	struct snd_info_buffer *rbuffer;
	struct snd_info_buffer *wbuffer;
	struct snd_info_entry *entry;
	void *file_private_data;
};

static int snd_info_version_init(void);
static void snd_info_disconnect(struct snd_info_entry *entry);

/*

 */

static struct snd_info_entry *snd_proc_root;
struct snd_info_entry *snd_seq_root;
EXPORT_SYMBOL(snd_seq_root);

#ifdef CONFIG_SND_OSSEMUL
struct snd_info_entry *snd_oss_root;
#endif

static int alloc_info_private(struct snd_info_entry *entry,
			      struct snd_info_private_data **ret)
{
	struct snd_info_private_data *data;

	if (!entry || !entry->p)
		return -ENODEV;
	if (!try_module_get(entry->module))
		return -EFAULT;
	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data) {
		module_put(entry->module);
		return -ENOMEM;
	}
	data->entry = entry;
	*ret = data;
	return 0;
}

static bool valid_pos(loff_t pos, size_t count)
{
	if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
		return false;
	if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
		return false;
	return true;
}

/*
 * file ops for binary proc files
 */
static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
{
	struct snd_info_private_data *data;
	struct snd_info_entry *entry;
	loff_t ret = -EINVAL, size;

	data = file->private_data;
	entry = data->entry;
	mutex_lock(&entry->access);
	if (entry->c.ops->llseek) {
		offset = entry->c.ops->llseek(entry,
					      data->file_private_data,
					      file, offset, orig);
		goto out;
	}

	size = entry->size;
	switch (orig) {
	case SEEK_SET:
		break;
	case SEEK_CUR:
		offset += file->f_pos;
		break;
	case SEEK_END:
		if (!size)
			goto out;
		offset += size;
		break;
	default:
		goto out;
	}
	if (offset < 0)
		goto out;
	if (size && offset > size)
		offset = size;
	file->f_pos = offset;
	ret = offset;
 out:
	mutex_unlock(&entry->access);
	return ret;
}

static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
				   size_t count, loff_t * offset)
{
	struct snd_info_private_data *data = file->private_data;
	struct snd_info_entry *entry = data->entry;
	size_t size;
	loff_t pos;

	pos = *offset;
	if (!valid_pos(pos, count))
		return -EIO;
	if (pos >= entry->size)
		return 0;
	size = entry->size - pos;
	size = min(count, size);
	size = entry->c.ops->read(entry, data->file_private_data,
				  file, buffer, size, pos);
	if ((ssize_t) size > 0)
		*offset = pos + size;
	return size;
}

static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer,
				    size_t count, loff_t * offset)
{
	struct snd_info_private_data *data = file->private_data;
	struct snd_info_entry *entry = data->entry;
	ssize_t size = 0;
	loff_t pos;

	pos = *offset;
	if (!valid_pos(pos, count))
		return -EIO;
	if (count > 0) {
		size_t maxsize = entry->size - pos;
		count = min(count, maxsize);
		size = entry->c.ops->write(entry, data->file_private_data,
					   file, buffer, count, pos);
	}
	if (size > 0)
		*offset = pos + size;
	return size;
}

static __poll_t snd_info_entry_poll(struct file *file, poll_table *wait)
{
	struct snd_info_private_data *data = file->private_data;
	struct snd_info_entry *entry = data->entry;
	__poll_t mask = 0;

	if (entry->c.ops->poll)
		return entry->c.ops->poll(entry,
					  data->file_private_data,
					  file, wait);
	if (entry->c.ops->read)
		mask |= EPOLLIN | EPOLLRDNORM;
	if (entry->c.ops->write)
		mask |= EPOLLOUT | EPOLLWRNORM;
	return mask;
}

static long snd_info_entry_ioctl(struct file *file, unsigned int cmd,
				unsigned long arg)
{
	struct snd_info_private_data *data = file->private_data;
	struct snd_info_entry *entry = data->entry;

	if (!entry->c.ops->ioctl)
		return -ENOTTY;
	return entry->c.ops->ioctl(entry, data->file_private_data,
				   file, cmd, arg);
}

static int snd_info_entry_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct inode *inode = file_inode(file);
	struct snd_info_private_data *data;
	struct snd_info_entry *entry;

	data = file->private_data;
	if (data == NULL)
		return 0;
	entry = data->entry;
	if (!entry->c.ops->mmap)
		return -ENXIO;
	return entry->c.ops->mmap(entry, data->file_private_data,
				  inode, file, vma);
}

static int snd_info_entry_open(struct inode *inode, struct file *file)
{
	struct snd_info_entry *entry = PDE_DATA(inode);
	struct snd_info_private_data *data;
	int mode, err;

	mutex_lock(&info_mutex);
	err = alloc_info_private(entry, &data);
	if (err < 0)
		goto unlock;

	mode = file->f_flags & O_ACCMODE;
	if (((mode == O_RDONLY || mode == O_RDWR) && !entry->c.ops->read) ||
	    ((mode == O_WRONLY || mode == O_RDWR) && !entry->c.ops->write)) {
		err = -ENODEV;
		goto error;
	}

	if (entry->c.ops->open) {
		err = entry->c.ops->open(entry, mode, &data->file_private_data);
		if (err < 0)
			goto error;
	}

	file->private_data = data;
	mutex_unlock(&info_mutex);
	return 0;

 error:
	kfree(data);
	module_put(entry->module);
 unlock:
	mutex_unlock(&info_mutex);
	return err;
}

static int snd_info_entry_release(struct inode *inode, struct file *file)
{
	struct snd_info_private_data *data = file->private_data;
	struct snd_info_entry *entry = data->entry;

	if (entry->c.ops->release)
		entry->c.ops->release(entry, file->f_flags & O_ACCMODE,
				      data->file_private_data);
	module_put(entry->module);
	kfree(data);
	return 0;
}

static const struct proc_ops snd_info_entry_operations =
{
	.proc_lseek	= snd_info_entry_llseek,
	.proc_read	= snd_info_entry_read,
	.proc_write	= snd_info_entry_write,
	.proc_poll	= snd_info_entry_poll,
	.proc_ioctl	= snd_info_entry_ioctl,
	.proc_mmap	= snd_info_entry_mmap,
	.proc_open	= snd_info_entry_open,
	.proc_release	= snd_info_entry_release,
};

/*
 * file ops for text proc files
 */
static ssize_t snd_info_text_entry_write(struct file *file,
					 const char __user *buffer,
					 size_t count, loff_t *offset)
{
	struct seq_file *m = file->private_data;
	struct snd_info_private_data *data = m->private;
	struct snd_info_entry *entry = data->entry;
	struct snd_info_buffer *buf;
	loff_t pos;
	size_t next;
	int err = 0;

	if (!entry->c.text.write)
		return -EIO;
	pos = *offset;
	if (!valid_pos(pos, count))
		return -EIO;
	next = pos + count;
	/* don't handle too large text inputs */
	if (next > 16 * 1024)
		return -EIO;
	mutex_lock(&entry->access);
	buf = data->wbuffer;
	if (!buf) {
		data->wbuffer = buf = kzalloc(sizeof(*buf), GFP_KERNEL);
		if (!buf) {
			err = -ENOMEM;
			goto error;
		}
	}
	if (next > buf->len) {
		char *nbuf = kvzalloc(PAGE_ALIGN(next), GFP_KERNEL);
		if (!nbuf) {
			err = -ENOMEM;
			goto error;
		}
		kvfree(buf->buffer);
		buf->buffer = nbuf;
		buf->len = PAGE_ALIGN(next);
	}
	if (copy_from_user(buf->buffer + pos, buffer, count)) {
		err = -EFAULT;
		goto error;
	}
	buf->size = next;
 error:
	mutex_unlock(&entry->access);
	if (err < 0)
		return err;
	*offset = next;
	return count;
}

static int snd_info_seq_show(struct seq_file *seq, void *p)
{
	struct snd_info_private_data *data = seq->private;
	struct snd_info_entry *entry = data->entry;

	if (!entry->c.text.read) {
		return -EIO;
	} else {
		data->rbuffer->buffer = (char *)seq; /* XXX hack! */
		entry->c.text.read(entry, data->rbuffer);
	}
	return 0;
}

static int snd_info_text_entry_open(struct inode *inode, struct file *file)
{
	struct snd_info_entry *entry = PDE_DATA(inode);
	struct snd_info_private_data *data;
	int err;

	mutex_lock(&info_mutex);
	err = alloc_info_private(entry, &data);
	if (err < 0)
		goto unlock;

	data->rbuffer = kzalloc(sizeof(*data->rbuffer), GFP_KERNEL);
	if (!data->rbuffer) {
		err = -ENOMEM;
		goto error;
	}
	if (entry->size)
		err = single_open_size(file, snd_info_seq_show, data,
				       entry->size);
	else
		err = single_open(file, snd_info_seq_show, data);
	if (err < 0)
		goto error;
	mutex_unlock(&info_mutex);
	return 0;

 error:
	kfree(data->rbuffer);
	kfree(data);
	module_put(entry->module);
 unlock:
	mutex_unlock(&info_mutex);
	return err;
}

static int snd_info_text_entry_release(struct inode *inode, struct file *file)
{
	struct seq_file *m = file->private_data;
	struct snd_info_private_data *data = m->private;
	struct snd_info_entry *entry = data->entry;

	if (data->wbuffer && entry->c.text.write)
		entry->c.text.write(entry, data->wbuffer);

	single_release(inode, file);
	kfree(data->rbuffer);
	if (data->wbuffer) {
		kvfree(data->wbuffer->buffer);
		kfree(data->wbuffer);
	}

	module_put(entry->module);
	kfree(data);
	return 0;
}

static const struct proc_ops snd_info_text_entry_ops =
{
	.proc_open	= snd_info_text_entry_open,
	.proc_release	= snd_info_text_entry_release,
	.proc_write	= snd_info_text_entry_write,
	.proc_lseek	= seq_lseek,
	.proc_read	= seq_read,
};

static struct snd_info_entry *create_subdir(struct module *mod,
					    const char *name)
{
	struct snd_info_entry *entry;

	entry = snd_info_create_module_entry(mod, name, NULL);
	if (!entry)
		return NULL;
	entry->mode = S_IFDIR | 0555;
	if (snd_info_register(entry) < 0) {
		snd_info_free_entry(entry);
		return NULL;
	}
	return entry;
}

static struct snd_info_entry *
snd_info_create_entry(const char *name, struct snd_info_entry *parent,
		      struct module *module);

int __init snd_info_init(void)
{
	snd_proc_root = snd_info_create_entry("asound", NULL, THIS_MODULE);
	if (!snd_proc_root)
		return -ENOMEM;
	snd_proc_root->mode = S_IFDIR | 0555;
	snd_proc_root->p = proc_mkdir("asound", NULL);
	if (!snd_proc_root->p)
		goto error;
#ifdef CONFIG_SND_OSSEMUL
	snd_oss_root = create_subdir(THIS_MODULE, "oss");
	if (!snd_oss_root)
		goto error;
#endif
#if IS_ENABLED(CONFIG_SND_SEQUENCER)
	snd_seq_root = create_subdir(THIS_MODULE, "seq");
	if (!snd_seq_root)
		goto error;
#endif
	if (snd_info_version_init() < 0 ||
	    snd_minor_info_init() < 0 ||
	    snd_minor_info_oss_init() < 0 ||
	    snd_card_info_init() < 0 ||
	    snd_info_minor_register() < 0)
		goto error;
	return 0;

 error:
	snd_info_free_entry(snd_proc_root);
	return -ENOMEM;
}

int __exit snd_info_done(void)
{
	snd_info_free_entry(snd_proc_root);
	return 0;
}

static void snd_card_id_read(struct snd_info_entry *entry,
			     struct snd_info_buffer *buffer)
{
	struct snd_card *card = entry->private_data;

	snd_iprintf(buffer, "%s\n", card->id);
}

/*
 * create a card proc file
 * called from init.c
 */
int snd_info_card_create(struct snd_card *card)
{
	char str[8];
	struct snd_info_entry *entry;

	if (snd_BUG_ON(!card))
		return -ENXIO;

	sprintf(str, "card%i", card->number);
	entry = create_subdir(card->module, str);
	if (!entry)
		return -ENOMEM;
	card->proc_root = entry;

	return snd_card_ro_proc_new(card, "id", card, snd_card_id_read);
}

/*
 * register the card proc file
 * called from init.c
 * can be called multiple times for reinitialization
 */
int snd_info_card_register(struct snd_card *card)
{
	struct proc_dir_entry *p;
	int err;

	if (snd_BUG_ON(!card))
		return -ENXIO;

	err = snd_info_register(card->proc_root);
	if (err < 0)
		return err;

	if (!strcmp(card->id, card->proc_root->name))
		return 0;

	if (card->proc_root_link)
		return 0;
	p = proc_symlink(card->id, snd_proc_root->p, card->proc_root->name);
	if (!p)
		return -ENOMEM;
	card->proc_root_link = p;
	return 0;
}

/*
 * called on card->id change
 */
void snd_info_card_id_change(struct snd_card *card)
{
	mutex_lock(&info_mutex);
	if (card->proc_root_link) {
		proc_remove(card->proc_root_link);
		card->proc_root_link = NULL;
	}
	if (strcmp(card->id, card->proc_root->name))
		card->proc_root_link = proc_symlink(card->id,
						    snd_proc_root->p,
						    card->proc_root->name);
	mutex_unlock(&info_mutex);
}

/*
 * de-register the card proc file
 * called from init.c
 */
void snd_info_card_disconnect(struct snd_card *card)
{
	if (!card)
		return;
	mutex_lock(&info_mutex);
	proc_remove(card->proc_root_link);
	card->proc_root_link = NULL;
	if (card->proc_root)
		snd_info_disconnect(card->proc_root);
	mutex_unlock(&info_mutex);
}

/*
 * release the card proc file resources
 * called from init.c
 */
int snd_info_card_free(struct snd_card *card)
{
	if (!card)
		return 0;
	snd_info_free_entry(card->proc_root);
	card->proc_root = NULL;
	return 0;
}


/**
 * snd_info_get_line - read one line from the procfs buffer
 * @buffer: the procfs buffer
 * @line: the buffer to store
 * @len: the max. buffer size
 *
 * Reads one line from the buffer and stores the string.
 *
 * Return: Zero if successful, or 1 if error or EOF.
 */
int snd_info_get_line(struct snd_info_buffer *buffer, char *line, int len)
{
	int c;

	if (snd_BUG_ON(!buffer || !buffer->buffer))
		return 1;
	if (len <= 0 || buffer->stop || buffer->error)
		return 1;
	while (!buffer->stop) {
		c = buffer->buffer[buffer->curr++];
		if (buffer->curr >= buffer->size)
			buffer->stop = 1;
		if (c == '\n')
			break;
		if (len > 1) {
			len--;
			*line++ = c;
		}
	}
	*line = '\0';
	return 0;
}
EXPORT_SYMBOL(snd_info_get_line);

/**
 * snd_info_get_str - parse a string token
 * @dest: the buffer to store the string token
 * @src: the original string
 * @len: the max. length of token - 1
 *
 * Parses the original string and copy a token to the given
 * string buffer.
 *
 * Return: The updated pointer of the original string so that
 * it can be used for the next call.
 */
const char *snd_info_get_str(char *dest, const char *src, int len)
{
	int c;

	while (*src == ' ' || *src == '\t')
		src++;
	if (*src == '"' || *src == '\'') {
		c = *src++;
		while (--len > 0 && *src && *src != c) {
			*dest++ = *src++;
		}
		if (*src == c)
			src++;
	} else {
		while (--len > 0 && *src && *src != ' ' && *src != '\t') {
			*dest++ = *src++;
		}
	}
	*dest = 0;
	while (*src == ' ' || *src == '\t')
		src++;
	return src;
}
EXPORT_SYMBOL(snd_info_get_str);

/*
 * snd_info_create_entry - create an info entry
 * @name: the proc file name
 * @parent: the parent directory
 *
 * Creates an info entry with the given file name and initializes as
 * the default state.
 *
 * Usually called from other functions such as
 * snd_info_create_card_entry().
 *
 * Return: The pointer of the new instance, or %NULL on failure.
 */
static struct snd_info_entry *
snd_info_create_entry(const char *name, struct snd_info_entry *parent,
		      struct module *module)
{
	struct snd_info_entry *entry;
	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (entry == NULL)
		return NULL;
	entry->name = kstrdup(name, GFP_KERNEL);
	if (entry->name == NULL) {
		kfree(entry);
		return NULL;
	}
	entry->mode = S_IFREG | 0444;
	entry->content = SNDRV_INFO_CONTENT_TEXT;
	mutex_init(&entry->access);
	INIT_LIST_HEAD(&entry->children);
	INIT_LIST_HEAD(&entry->list);
	entry->parent = parent;
	entry->module = module;
	if (parent) {
		mutex_lock(&parent->access);
		list_add_tail(&entry->list, &parent->children);
		mutex_unlock(&parent->access);
	}
	return entry;
}

/**
 * snd_info_create_module_entry - create an info entry for the given module
 * @module: the module pointer
 * @name: the file name
 * @parent: the parent directory
 *
 * Creates a new info entry and assigns it to the given module.
 *
 * Return: The pointer of the new instance, or %NULL on failure.
 */
struct snd_info_entry *snd_info_create_module_entry(struct module * module,
					       const char *name,
					       struct snd_info_entry *parent)
{
	if (!parent)
		parent = snd_proc_root;
	return snd_info_create_entry(name, parent, module);
}
EXPORT_SYMBOL(snd_info_create_module_entry);

/**
 * snd_info_create_card_entry - create an info entry for the given card
 * @card: the card instance
 * @name: the file name
 * @parent: the parent directory
 *
 * Creates a new info entry and assigns it to the given card.
 *
 * Return: The pointer of the new instance, or %NULL on failure.
 */
struct snd_info_entry *snd_info_create_card_entry(struct snd_card *card,
					     const char *name,
					     struct snd_info_entry * parent)
{
	if (!parent)
		parent = card->proc_root;
	return snd_info_create_entry(name, parent, card->module);
}
EXPORT_SYMBOL(snd_info_create_card_entry);

static void snd_info_disconnect(struct snd_info_entry *entry)
{
	struct snd_info_entry *p;

	if (!entry->p)
		return;
	list_for_each_entry(p, &entry->children, list)
		snd_info_disconnect(p);
	proc_remove(entry->p);
	entry->p = NULL;
}

/**
 * snd_info_free_entry - release the info entry
 * @entry: the info entry
 *
 * Releases the info entry.
 */
void snd_info_free_entry(struct snd_info_entry * entry)
{
	struct snd_info_entry *p, *n;

	if (!entry)
		return;
	if (entry->p) {
		mutex_lock(&info_mutex);
		snd_info_disconnect(entry);
		mutex_unlock(&info_mutex);
	}

	/* free all children at first */
	list_for_each_entry_safe(p, n, &entry->children, list)
		snd_info_free_entry(p);

	p = entry->parent;
	if (p) {
		mutex_lock(&p->access);
		list_del(&entry->list);
		mutex_unlock(&p->access);
	}
	kfree(entry->name);
	if (entry->private_free)
		entry->private_free(entry);
	kfree(entry);
}
EXPORT_SYMBOL(snd_info_free_entry);

static int __snd_info_register(struct snd_info_entry *entry)
{
	struct proc_dir_entry *root, *p = NULL;

	if (snd_BUG_ON(!entry))
		return -ENXIO;
	root = entry->parent == NULL ? snd_proc_root->p : entry->parent->p;
	mutex_lock(&info_mutex);
	if (entry->p || !root)
		goto unlock;
	if (S_ISDIR(entry->mode)) {
		p = proc_mkdir_mode(entry->name, entry->mode, root);
		if (!p) {
			mutex_unlock(&info_mutex);
			return -ENOMEM;
		}
	} else {
		const struct proc_ops *ops;
		if (entry->content == SNDRV_INFO_CONTENT_DATA)
			ops = &snd_info_entry_operations;
		else
			ops = &snd_info_text_entry_ops;
		p = proc_create_data(entry->name, entry->mode, root,
				     ops, entry);
		if (!p) {
			mutex_unlock(&info_mutex);
			return -ENOMEM;
		}
		proc_set_size(p, entry->size);
	}
	entry->p = p;
 unlock:
	mutex_unlock(&info_mutex);
	return 0;
}

/**
 * snd_info_register - register the info entry
 * @entry: the info entry
 *
 * Registers the proc info entry.
 * The all children entries are registered recursively.
 *
 * Return: Zero if successful, or a negative error code on failure.
 */
int snd_info_register(struct snd_info_entry *entry)
{
	struct snd_info_entry *p;
	int err;

	if (!entry->p) {
		err = __snd_info_register(entry);
		if (err < 0)
			return err;
	}

	list_for_each_entry(p, &entry->children, list) {
		err = snd_info_register(p);
		if (err < 0)
			return err;
	}

	return 0;
}
EXPORT_SYMBOL(snd_info_register);

/**
 * snd_card_rw_proc_new - Create a read/write text proc file entry for the card
 * @card: the card instance
 * @name: the file name
 * @private_data: the arbitrary private data
 * @read: the read callback
 * @write: the write callback, NULL for read-only
 *
 * This proc file entry will be registered via snd_card_register() call, and
 * it will be removed automatically at the card removal, too.
 */
int snd_card_rw_proc_new(struct snd_card *card, const char *name,
			 void *private_data,
			 void (*read)(struct snd_info_entry *,
				      struct snd_info_buffer *),
			 void (*write)(struct snd_info_entry *entry,
				       struct snd_info_buffer *buffer))
{
	struct snd_info_entry *entry;

	entry = snd_info_create_card_entry(card, name, card->proc_root);
	if (!entry)
		return -ENOMEM;
	snd_info_set_text_ops(entry, private_data, read);
	if (write) {
		entry->mode |= 0200;
		entry->c.text.write = write;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(snd_card_rw_proc_new);

/*

 */

static void snd_info_version_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
{
	snd_iprintf(buffer,
		    "Advanced Linux Sound Architecture Driver Version k%s.\n",
		    init_utsname()->release);
}

static int __init snd_info_version_init(void)
{
	struct snd_info_entry *entry;

	entry = snd_info_create_module_entry(THIS_MODULE, "version", NULL);
	if (entry == NULL)
		return -ENOMEM;
	entry->c.text.read = snd_info_version_read;
	return snd_info_register(entry); /* freed in error path */
}