xref: /linux/sound/core/info.c (revision 2cfe9bbec56ea579135cdd92409fff371841904f) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Information interface for ALSA driver
4  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
5  */
6 
7 #include <linux/init.h>
8 #include <linux/time.h>
9 #include <linux/mm.h>
10 #include <linux/slab.h>
11 #include <linux/string.h>
12 #include <linux/module.h>
13 #include <sound/core.h>
14 #include <sound/minors.h>
15 #include <sound/info.h>
16 #include <linux/utsname.h>
17 #include <linux/proc_fs.h>
18 #include <linux/mutex.h>
19 
20 int snd_info_check_reserved_words(const char *str)
21 {
22 	static const char * const reserved[] =
23 	{
24 		"version",
25 		"meminfo",
26 		"memdebug",
27 		"detect",
28 		"devices",
29 		"oss",
30 		"cards",
31 		"timers",
32 		"synth",
33 		"pcm",
34 		"seq",
35 		NULL
36 	};
37 	const char * const *xstr = reserved;
38 
39 	while (*xstr) {
40 		if (!strcmp(*xstr, str))
41 			return 0;
42 		xstr++;
43 	}
44 	if (!strncmp(str, "card", 4))
45 		return 0;
46 	return 1;
47 }
48 
49 static DEFINE_MUTEX(info_mutex);
50 
51 struct snd_info_private_data {
52 	struct snd_info_buffer *rbuffer;
53 	struct snd_info_buffer *wbuffer;
54 	struct snd_info_entry *entry;
55 	void *file_private_data;
56 };
57 
58 static int snd_info_version_init(void);
59 static void snd_info_disconnect(struct snd_info_entry *entry);
60 
61 /*
62 
63  */
64 
65 static struct snd_info_entry *snd_proc_root;
66 struct snd_info_entry *snd_seq_root;
67 EXPORT_SYMBOL(snd_seq_root);
68 
69 #ifdef CONFIG_SND_OSSEMUL
70 struct snd_info_entry *snd_oss_root;
71 #endif
72 
73 static int alloc_info_private(struct snd_info_entry *entry,
74 			      struct snd_info_private_data **ret)
75 {
76 	struct snd_info_private_data *data;
77 
78 	if (!entry || !entry->p)
79 		return -ENODEV;
80 	if (!try_module_get(entry->module))
81 		return -EFAULT;
82 	data = kzalloc(sizeof(*data), GFP_KERNEL);
83 	if (!data) {
84 		module_put(entry->module);
85 		return -ENOMEM;
86 	}
87 	data->entry = entry;
88 	*ret = data;
89 	return 0;
90 }
91 
92 static bool valid_pos(loff_t pos, size_t count)
93 {
94 	if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
95 		return false;
96 	if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
97 		return false;
98 	return true;
99 }
100 
101 /*
102  * file ops for binary proc files
103  */
104 static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
105 {
106 	struct snd_info_private_data *data;
107 	struct snd_info_entry *entry;
108 	loff_t ret = -EINVAL, size;
109 
110 	data = file->private_data;
111 	entry = data->entry;
112 	mutex_lock(&entry->access);
113 	if (entry->c.ops->llseek) {
114 		offset = entry->c.ops->llseek(entry,
115 					      data->file_private_data,
116 					      file, offset, orig);
117 		goto out;
118 	}
119 
120 	size = entry->size;
121 	switch (orig) {
122 	case SEEK_SET:
123 		break;
124 	case SEEK_CUR:
125 		offset += file->f_pos;
126 		break;
127 	case SEEK_END:
128 		if (!size)
129 			goto out;
130 		offset += size;
131 		break;
132 	default:
133 		goto out;
134 	}
135 	if (offset < 0)
136 		goto out;
137 	if (size && offset > size)
138 		offset = size;
139 	file->f_pos = offset;
140 	ret = offset;
141  out:
142 	mutex_unlock(&entry->access);
143 	return ret;
144 }
145 
146 static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
147 				   size_t count, loff_t * offset)
148 {
149 	struct snd_info_private_data *data = file->private_data;
150 	struct snd_info_entry *entry = data->entry;
151 	size_t size;
152 	loff_t pos;
153 
154 	pos = *offset;
155 	if (!valid_pos(pos, count))
156 		return -EIO;
157 	if (pos >= entry->size)
158 		return 0;
159 	size = entry->size - pos;
160 	size = min(count, size);
161 	size = entry->c.ops->read(entry, data->file_private_data,
162 				  file, buffer, size, pos);
163 	if ((ssize_t) size > 0)
164 		*offset = pos + size;
165 	return size;
166 }
167 
168 static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer,
169 				    size_t count, loff_t * offset)
170 {
171 	struct snd_info_private_data *data = file->private_data;
172 	struct snd_info_entry *entry = data->entry;
173 	ssize_t size = 0;
174 	loff_t pos;
175 
176 	pos = *offset;
177 	if (!valid_pos(pos, count))
178 		return -EIO;
179 	if (count > 0) {
180 		size_t maxsize = entry->size - pos;
181 		count = min(count, maxsize);
182 		size = entry->c.ops->write(entry, data->file_private_data,
183 					   file, buffer, count, pos);
184 	}
185 	if (size > 0)
186 		*offset = pos + size;
187 	return size;
188 }
189 
190 static __poll_t snd_info_entry_poll(struct file *file, poll_table *wait)
191 {
192 	struct snd_info_private_data *data = file->private_data;
193 	struct snd_info_entry *entry = data->entry;
194 	__poll_t mask = 0;
195 
196 	if (entry->c.ops->poll)
197 		return entry->c.ops->poll(entry,
198 					  data->file_private_data,
199 					  file, wait);
200 	if (entry->c.ops->read)
201 		mask |= EPOLLIN | EPOLLRDNORM;
202 	if (entry->c.ops->write)
203 		mask |= EPOLLOUT | EPOLLWRNORM;
204 	return mask;
205 }
206 
207 static long snd_info_entry_ioctl(struct file *file, unsigned int cmd,
208 				unsigned long arg)
209 {
210 	struct snd_info_private_data *data = file->private_data;
211 	struct snd_info_entry *entry = data->entry;
212 
213 	if (!entry->c.ops->ioctl)
214 		return -ENOTTY;
215 	return entry->c.ops->ioctl(entry, data->file_private_data,
216 				   file, cmd, arg);
217 }
218 
219 static int snd_info_entry_mmap(struct file *file, struct vm_area_struct *vma)
220 {
221 	struct inode *inode = file_inode(file);
222 	struct snd_info_private_data *data;
223 	struct snd_info_entry *entry;
224 
225 	data = file->private_data;
226 	if (data == NULL)
227 		return 0;
228 	entry = data->entry;
229 	if (!entry->c.ops->mmap)
230 		return -ENXIO;
231 	return entry->c.ops->mmap(entry, data->file_private_data,
232 				  inode, file, vma);
233 }
234 
235 static int snd_info_entry_open(struct inode *inode, struct file *file)
236 {
237 	struct snd_info_entry *entry = pde_data(inode);
238 	struct snd_info_private_data *data;
239 	int mode, err;
240 
241 	mutex_lock(&info_mutex);
242 	err = alloc_info_private(entry, &data);
243 	if (err < 0)
244 		goto unlock;
245 
246 	mode = file->f_flags & O_ACCMODE;
247 	if (((mode == O_RDONLY || mode == O_RDWR) && !entry->c.ops->read) ||
248 	    ((mode == O_WRONLY || mode == O_RDWR) && !entry->c.ops->write)) {
249 		err = -ENODEV;
250 		goto error;
251 	}
252 
253 	if (entry->c.ops->open) {
254 		err = entry->c.ops->open(entry, mode, &data->file_private_data);
255 		if (err < 0)
256 			goto error;
257 	}
258 
259 	file->private_data = data;
260 	mutex_unlock(&info_mutex);
261 	return 0;
262 
263  error:
264 	kfree(data);
265 	module_put(entry->module);
266  unlock:
267 	mutex_unlock(&info_mutex);
268 	return err;
269 }
270 
271 static int snd_info_entry_release(struct inode *inode, struct file *file)
272 {
273 	struct snd_info_private_data *data = file->private_data;
274 	struct snd_info_entry *entry = data->entry;
275 
276 	if (entry->c.ops->release)
277 		entry->c.ops->release(entry, file->f_flags & O_ACCMODE,
278 				      data->file_private_data);
279 	module_put(entry->module);
280 	kfree(data);
281 	return 0;
282 }
283 
284 static const struct proc_ops snd_info_entry_operations =
285 {
286 	.proc_lseek	= snd_info_entry_llseek,
287 	.proc_read	= snd_info_entry_read,
288 	.proc_write	= snd_info_entry_write,
289 	.proc_poll	= snd_info_entry_poll,
290 	.proc_ioctl	= snd_info_entry_ioctl,
291 	.proc_mmap	= snd_info_entry_mmap,
292 	.proc_open	= snd_info_entry_open,
293 	.proc_release	= snd_info_entry_release,
294 };
295 
296 /*
297  * file ops for text proc files
298  */
299 static ssize_t snd_info_text_entry_write(struct file *file,
300 					 const char __user *buffer,
301 					 size_t count, loff_t *offset)
302 {
303 	struct seq_file *m = file->private_data;
304 	struct snd_info_private_data *data = m->private;
305 	struct snd_info_entry *entry = data->entry;
306 	struct snd_info_buffer *buf;
307 	loff_t pos;
308 	size_t next;
309 	int err = 0;
310 
311 	if (!entry->c.text.write)
312 		return -EIO;
313 	pos = *offset;
314 	if (!valid_pos(pos, count))
315 		return -EIO;
316 	next = pos + count;
317 	/* don't handle too large text inputs */
318 	if (next > 16 * 1024)
319 		return -EIO;
320 	mutex_lock(&entry->access);
321 	buf = data->wbuffer;
322 	if (!buf) {
323 		data->wbuffer = buf = kzalloc(sizeof(*buf), GFP_KERNEL);
324 		if (!buf) {
325 			err = -ENOMEM;
326 			goto error;
327 		}
328 	}
329 	if (next > buf->len) {
330 		char *nbuf = kvzalloc(PAGE_ALIGN(next), GFP_KERNEL);
331 		if (!nbuf) {
332 			err = -ENOMEM;
333 			goto error;
334 		}
335 		kvfree(buf->buffer);
336 		buf->buffer = nbuf;
337 		buf->len = PAGE_ALIGN(next);
338 	}
339 	if (copy_from_user(buf->buffer + pos, buffer, count)) {
340 		err = -EFAULT;
341 		goto error;
342 	}
343 	buf->size = next;
344  error:
345 	mutex_unlock(&entry->access);
346 	if (err < 0)
347 		return err;
348 	*offset = next;
349 	return count;
350 }
351 
352 static int snd_info_seq_show(struct seq_file *seq, void *p)
353 {
354 	struct snd_info_private_data *data = seq->private;
355 	struct snd_info_entry *entry = data->entry;
356 
357 	if (!entry->c.text.read) {
358 		return -EIO;
359 	} else {
360 		data->rbuffer->buffer = (char *)seq; /* XXX hack! */
361 		entry->c.text.read(entry, data->rbuffer);
362 	}
363 	return 0;
364 }
365 
366 static int snd_info_text_entry_open(struct inode *inode, struct file *file)
367 {
368 	struct snd_info_entry *entry = pde_data(inode);
369 	struct snd_info_private_data *data;
370 	int err;
371 
372 	mutex_lock(&info_mutex);
373 	err = alloc_info_private(entry, &data);
374 	if (err < 0)
375 		goto unlock;
376 
377 	data->rbuffer = kzalloc(sizeof(*data->rbuffer), GFP_KERNEL);
378 	if (!data->rbuffer) {
379 		err = -ENOMEM;
380 		goto error;
381 	}
382 	if (entry->size)
383 		err = single_open_size(file, snd_info_seq_show, data,
384 				       entry->size);
385 	else
386 		err = single_open(file, snd_info_seq_show, data);
387 	if (err < 0)
388 		goto error;
389 	mutex_unlock(&info_mutex);
390 	return 0;
391 
392  error:
393 	kfree(data->rbuffer);
394 	kfree(data);
395 	module_put(entry->module);
396  unlock:
397 	mutex_unlock(&info_mutex);
398 	return err;
399 }
400 
401 static int snd_info_text_entry_release(struct inode *inode, struct file *file)
402 {
403 	struct seq_file *m = file->private_data;
404 	struct snd_info_private_data *data = m->private;
405 	struct snd_info_entry *entry = data->entry;
406 
407 	if (data->wbuffer && entry->c.text.write)
408 		entry->c.text.write(entry, data->wbuffer);
409 
410 	single_release(inode, file);
411 	kfree(data->rbuffer);
412 	if (data->wbuffer) {
413 		kvfree(data->wbuffer->buffer);
414 		kfree(data->wbuffer);
415 	}
416 
417 	module_put(entry->module);
418 	kfree(data);
419 	return 0;
420 }
421 
422 static const struct proc_ops snd_info_text_entry_ops =
423 {
424 	.proc_open	= snd_info_text_entry_open,
425 	.proc_release	= snd_info_text_entry_release,
426 	.proc_write	= snd_info_text_entry_write,
427 	.proc_lseek	= seq_lseek,
428 	.proc_read	= seq_read,
429 };
430 
431 static struct snd_info_entry *create_subdir(struct module *mod,
432 					    const char *name)
433 {
434 	struct snd_info_entry *entry;
435 
436 	entry = snd_info_create_module_entry(mod, name, NULL);
437 	if (!entry)
438 		return NULL;
439 	entry->mode = S_IFDIR | 0555;
440 	if (snd_info_register(entry) < 0) {
441 		snd_info_free_entry(entry);
442 		return NULL;
443 	}
444 	return entry;
445 }
446 
447 static struct snd_info_entry *
448 snd_info_create_entry(const char *name, struct snd_info_entry *parent,
449 		      struct module *module);
450 
451 int __init snd_info_init(void)
452 {
453 	snd_proc_root = snd_info_create_entry("asound", NULL, THIS_MODULE);
454 	if (!snd_proc_root)
455 		return -ENOMEM;
456 	snd_proc_root->mode = S_IFDIR | 0555;
457 	snd_proc_root->p = proc_mkdir("asound", NULL);
458 	if (!snd_proc_root->p)
459 		goto error;
460 #ifdef CONFIG_SND_OSSEMUL
461 	snd_oss_root = create_subdir(THIS_MODULE, "oss");
462 	if (!snd_oss_root)
463 		goto error;
464 #endif
465 #if IS_ENABLED(CONFIG_SND_SEQUENCER)
466 	snd_seq_root = create_subdir(THIS_MODULE, "seq");
467 	if (!snd_seq_root)
468 		goto error;
469 #endif
470 	if (snd_info_version_init() < 0 ||
471 	    snd_minor_info_init() < 0 ||
472 	    snd_minor_info_oss_init() < 0 ||
473 	    snd_card_info_init() < 0 ||
474 	    snd_info_minor_register() < 0)
475 		goto error;
476 	return 0;
477 
478  error:
479 	snd_info_free_entry(snd_proc_root);
480 	return -ENOMEM;
481 }
482 
483 int __exit snd_info_done(void)
484 {
485 	snd_info_free_entry(snd_proc_root);
486 	return 0;
487 }
488 
489 static void snd_card_id_read(struct snd_info_entry *entry,
490 			     struct snd_info_buffer *buffer)
491 {
492 	struct snd_card *card = entry->private_data;
493 
494 	snd_iprintf(buffer, "%s\n", card->id);
495 }
496 
497 /*
498  * create a card proc file
499  * called from init.c
500  */
501 int snd_info_card_create(struct snd_card *card)
502 {
503 	char str[8];
504 	struct snd_info_entry *entry;
505 
506 	if (snd_BUG_ON(!card))
507 		return -ENXIO;
508 
509 	sprintf(str, "card%i", card->number);
510 	entry = create_subdir(card->module, str);
511 	if (!entry)
512 		return -ENOMEM;
513 	card->proc_root = entry;
514 
515 	return snd_card_ro_proc_new(card, "id", card, snd_card_id_read);
516 }
517 
518 /*
519  * register the card proc file
520  * called from init.c
521  * can be called multiple times for reinitialization
522  */
523 int snd_info_card_register(struct snd_card *card)
524 {
525 	struct proc_dir_entry *p;
526 	int err;
527 
528 	if (snd_BUG_ON(!card))
529 		return -ENXIO;
530 
531 	err = snd_info_register(card->proc_root);
532 	if (err < 0)
533 		return err;
534 
535 	if (!strcmp(card->id, card->proc_root->name))
536 		return 0;
537 
538 	if (card->proc_root_link)
539 		return 0;
540 	p = proc_symlink(card->id, snd_proc_root->p, card->proc_root->name);
541 	if (!p)
542 		return -ENOMEM;
543 	card->proc_root_link = p;
544 	return 0;
545 }
546 
547 /*
548  * called on card->id change
549  */
550 void snd_info_card_id_change(struct snd_card *card)
551 {
552 	mutex_lock(&info_mutex);
553 	if (card->proc_root_link) {
554 		proc_remove(card->proc_root_link);
555 		card->proc_root_link = NULL;
556 	}
557 	if (strcmp(card->id, card->proc_root->name))
558 		card->proc_root_link = proc_symlink(card->id,
559 						    snd_proc_root->p,
560 						    card->proc_root->name);
561 	mutex_unlock(&info_mutex);
562 }
563 
564 /*
565  * de-register the card proc file
566  * called from init.c
567  */
568 void snd_info_card_disconnect(struct snd_card *card)
569 {
570 	if (!card)
571 		return;
572 	mutex_lock(&info_mutex);
573 	proc_remove(card->proc_root_link);
574 	card->proc_root_link = NULL;
575 	if (card->proc_root)
576 		snd_info_disconnect(card->proc_root);
577 	mutex_unlock(&info_mutex);
578 }
579 
580 /*
581  * release the card proc file resources
582  * called from init.c
583  */
584 int snd_info_card_free(struct snd_card *card)
585 {
586 	if (!card)
587 		return 0;
588 	snd_info_free_entry(card->proc_root);
589 	card->proc_root = NULL;
590 	return 0;
591 }
592 
593 
594 /**
595  * snd_info_get_line - read one line from the procfs buffer
596  * @buffer: the procfs buffer
597  * @line: the buffer to store
598  * @len: the max. buffer size
599  *
600  * Reads one line from the buffer and stores the string.
601  *
602  * Return: Zero if successful, or 1 if error or EOF.
603  */
604 int snd_info_get_line(struct snd_info_buffer *buffer, char *line, int len)
605 {
606 	int c;
607 
608 	if (snd_BUG_ON(!buffer))
609 		return 1;
610 	if (!buffer->buffer)
611 		return 1;
612 	if (len <= 0 || buffer->stop || buffer->error)
613 		return 1;
614 	while (!buffer->stop) {
615 		c = buffer->buffer[buffer->curr++];
616 		if (buffer->curr >= buffer->size)
617 			buffer->stop = 1;
618 		if (c == '\n')
619 			break;
620 		if (len > 1) {
621 			len--;
622 			*line++ = c;
623 		}
624 	}
625 	*line = '\0';
626 	return 0;
627 }
628 EXPORT_SYMBOL(snd_info_get_line);
629 
630 /**
631  * snd_info_get_str - parse a string token
632  * @dest: the buffer to store the string token
633  * @src: the original string
634  * @len: the max. length of token - 1
635  *
636  * Parses the original string and copy a token to the given
637  * string buffer.
638  *
639  * Return: The updated pointer of the original string so that
640  * it can be used for the next call.
641  */
642 const char *snd_info_get_str(char *dest, const char *src, int len)
643 {
644 	int c;
645 
646 	while (*src == ' ' || *src == '\t')
647 		src++;
648 	if (*src == '"' || *src == '\'') {
649 		c = *src++;
650 		while (--len > 0 && *src && *src != c) {
651 			*dest++ = *src++;
652 		}
653 		if (*src == c)
654 			src++;
655 	} else {
656 		while (--len > 0 && *src && *src != ' ' && *src != '\t') {
657 			*dest++ = *src++;
658 		}
659 	}
660 	*dest = 0;
661 	while (*src == ' ' || *src == '\t')
662 		src++;
663 	return src;
664 }
665 EXPORT_SYMBOL(snd_info_get_str);
666 
667 /*
668  * snd_info_create_entry - create an info entry
669  * @name: the proc file name
670  * @parent: the parent directory
671  *
672  * Creates an info entry with the given file name and initializes as
673  * the default state.
674  *
675  * Usually called from other functions such as
676  * snd_info_create_card_entry().
677  *
678  * Return: The pointer of the new instance, or %NULL on failure.
679  */
680 static struct snd_info_entry *
681 snd_info_create_entry(const char *name, struct snd_info_entry *parent,
682 		      struct module *module)
683 {
684 	struct snd_info_entry *entry;
685 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
686 	if (entry == NULL)
687 		return NULL;
688 	entry->name = kstrdup(name, GFP_KERNEL);
689 	if (entry->name == NULL) {
690 		kfree(entry);
691 		return NULL;
692 	}
693 	entry->mode = S_IFREG | 0444;
694 	entry->content = SNDRV_INFO_CONTENT_TEXT;
695 	mutex_init(&entry->access);
696 	INIT_LIST_HEAD(&entry->children);
697 	INIT_LIST_HEAD(&entry->list);
698 	entry->parent = parent;
699 	entry->module = module;
700 	if (parent) {
701 		mutex_lock(&parent->access);
702 		list_add_tail(&entry->list, &parent->children);
703 		mutex_unlock(&parent->access);
704 	}
705 	return entry;
706 }
707 
708 /**
709  * snd_info_create_module_entry - create an info entry for the given module
710  * @module: the module pointer
711  * @name: the file name
712  * @parent: the parent directory
713  *
714  * Creates a new info entry and assigns it to the given module.
715  *
716  * Return: The pointer of the new instance, or %NULL on failure.
717  */
718 struct snd_info_entry *snd_info_create_module_entry(struct module * module,
719 					       const char *name,
720 					       struct snd_info_entry *parent)
721 {
722 	if (!parent)
723 		parent = snd_proc_root;
724 	return snd_info_create_entry(name, parent, module);
725 }
726 EXPORT_SYMBOL(snd_info_create_module_entry);
727 
728 /**
729  * snd_info_create_card_entry - create an info entry for the given card
730  * @card: the card instance
731  * @name: the file name
732  * @parent: the parent directory
733  *
734  * Creates a new info entry and assigns it to the given card.
735  *
736  * Return: The pointer of the new instance, or %NULL on failure.
737  */
738 struct snd_info_entry *snd_info_create_card_entry(struct snd_card *card,
739 					     const char *name,
740 					     struct snd_info_entry * parent)
741 {
742 	if (!parent)
743 		parent = card->proc_root;
744 	return snd_info_create_entry(name, parent, card->module);
745 }
746 EXPORT_SYMBOL(snd_info_create_card_entry);
747 
748 static void snd_info_disconnect(struct snd_info_entry *entry)
749 {
750 	struct snd_info_entry *p;
751 
752 	if (!entry->p)
753 		return;
754 	list_for_each_entry(p, &entry->children, list)
755 		snd_info_disconnect(p);
756 	proc_remove(entry->p);
757 	entry->p = NULL;
758 }
759 
760 /**
761  * snd_info_free_entry - release the info entry
762  * @entry: the info entry
763  *
764  * Releases the info entry.
765  */
766 void snd_info_free_entry(struct snd_info_entry * entry)
767 {
768 	struct snd_info_entry *p, *n;
769 
770 	if (!entry)
771 		return;
772 	if (entry->p) {
773 		mutex_lock(&info_mutex);
774 		snd_info_disconnect(entry);
775 		mutex_unlock(&info_mutex);
776 	}
777 
778 	/* free all children at first */
779 	list_for_each_entry_safe(p, n, &entry->children, list)
780 		snd_info_free_entry(p);
781 
782 	p = entry->parent;
783 	if (p) {
784 		mutex_lock(&p->access);
785 		list_del(&entry->list);
786 		mutex_unlock(&p->access);
787 	}
788 	kfree(entry->name);
789 	if (entry->private_free)
790 		entry->private_free(entry);
791 	kfree(entry);
792 }
793 EXPORT_SYMBOL(snd_info_free_entry);
794 
795 static int __snd_info_register(struct snd_info_entry *entry)
796 {
797 	struct proc_dir_entry *root, *p = NULL;
798 
799 	if (snd_BUG_ON(!entry))
800 		return -ENXIO;
801 	root = entry->parent == NULL ? snd_proc_root->p : entry->parent->p;
802 	mutex_lock(&info_mutex);
803 	if (entry->p || !root)
804 		goto unlock;
805 	if (S_ISDIR(entry->mode)) {
806 		p = proc_mkdir_mode(entry->name, entry->mode, root);
807 		if (!p) {
808 			mutex_unlock(&info_mutex);
809 			return -ENOMEM;
810 		}
811 	} else {
812 		const struct proc_ops *ops;
813 		if (entry->content == SNDRV_INFO_CONTENT_DATA)
814 			ops = &snd_info_entry_operations;
815 		else
816 			ops = &snd_info_text_entry_ops;
817 		p = proc_create_data(entry->name, entry->mode, root,
818 				     ops, entry);
819 		if (!p) {
820 			mutex_unlock(&info_mutex);
821 			return -ENOMEM;
822 		}
823 		proc_set_size(p, entry->size);
824 	}
825 	entry->p = p;
826  unlock:
827 	mutex_unlock(&info_mutex);
828 	return 0;
829 }
830 
831 /**
832  * snd_info_register - register the info entry
833  * @entry: the info entry
834  *
835  * Registers the proc info entry.
836  * The all children entries are registered recursively.
837  *
838  * Return: Zero if successful, or a negative error code on failure.
839  */
840 int snd_info_register(struct snd_info_entry *entry)
841 {
842 	struct snd_info_entry *p;
843 	int err;
844 
845 	if (!entry->p) {
846 		err = __snd_info_register(entry);
847 		if (err < 0)
848 			return err;
849 	}
850 
851 	list_for_each_entry(p, &entry->children, list) {
852 		err = snd_info_register(p);
853 		if (err < 0)
854 			return err;
855 	}
856 
857 	return 0;
858 }
859 EXPORT_SYMBOL(snd_info_register);
860 
861 /**
862  * snd_card_rw_proc_new - Create a read/write text proc file entry for the card
863  * @card: the card instance
864  * @name: the file name
865  * @private_data: the arbitrary private data
866  * @read: the read callback
867  * @write: the write callback, NULL for read-only
868  *
869  * This proc file entry will be registered via snd_card_register() call, and
870  * it will be removed automatically at the card removal, too.
871  *
872  * Return: zero if successful, or a negative error code
873  */
874 int snd_card_rw_proc_new(struct snd_card *card, const char *name,
875 			 void *private_data,
876 			 void (*read)(struct snd_info_entry *,
877 				      struct snd_info_buffer *),
878 			 void (*write)(struct snd_info_entry *entry,
879 				       struct snd_info_buffer *buffer))
880 {
881 	struct snd_info_entry *entry;
882 
883 	entry = snd_info_create_card_entry(card, name, card->proc_root);
884 	if (!entry)
885 		return -ENOMEM;
886 	snd_info_set_text_ops(entry, private_data, read);
887 	if (write) {
888 		entry->mode |= 0200;
889 		entry->c.text.write = write;
890 	}
891 	return 0;
892 }
893 EXPORT_SYMBOL_GPL(snd_card_rw_proc_new);
894 
895 /*
896 
897  */
898 
899 static void snd_info_version_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
900 {
901 	snd_iprintf(buffer,
902 		    "Advanced Linux Sound Architecture Driver Version k%s.\n",
903 		    init_utsname()->release);
904 }
905 
906 static int __init snd_info_version_init(void)
907 {
908 	struct snd_info_entry *entry;
909 
910 	entry = snd_info_create_module_entry(THIS_MODULE, "version", NULL);
911 	if (entry == NULL)
912 		return -ENOMEM;
913 	entry->c.text.read = snd_info_version_read;
914 	return snd_info_register(entry); /* freed in error path */
915 }
916