init.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *  Initialization routines
   4 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   5 */
   6
   7#include <linux/init.h>
   8#include <linux/sched.h>
   9#include <linux/module.h>
  10#include <linux/device.h>
  11#include <linux/file.h>
  12#include <linux/slab.h>
  13#include <linux/time.h>
  14#include <linux/ctype.h>
  15#include <linux/pm.h>
  16#include <linux/debugfs.h>
  17#include <linux/completion.h>
  18#include <linux/interrupt.h>
  19
  20#include <sound/core.h>
  21#include <sound/control.h>
  22#include <sound/info.h>
  23
  24/* monitor files for graceful shutdown (hotplug) */
  25struct snd_monitor_file {
  26	struct file *file;
  27	const struct file_operations *disconnected_f_op;
  28	struct list_head shutdown_list;	/* still need to shutdown */
  29	struct list_head list;	/* link of monitor files */
  30};
  31
  32static DEFINE_SPINLOCK(shutdown_lock);
  33static LIST_HEAD(shutdown_files);
  34
  35static const struct file_operations snd_shutdown_f_ops;
  36
  37/* locked for registering/using */
  38static DECLARE_BITMAP(snd_cards_lock, SNDRV_CARDS);
  39static struct snd_card *snd_cards[SNDRV_CARDS];
  40
  41static DEFINE_MUTEX(snd_card_mutex);
  42
  43static char *slots[SNDRV_CARDS];
  44module_param_array(slots, charp, NULL, 0444);
  45MODULE_PARM_DESC(slots, "Module names assigned to the slots.");
  46
  47/* return non-zero if the given index is reserved for the given
  48 * module via slots option
  49 */
  50static int module_slot_match(struct module *module, int idx)
  51{
  52	int match = 1;
  53#ifdef CONFIG_MODULES
  54	const char *s1, *s2;
  55
  56	if (!module || !*module->name || !slots[idx])
  57		return 0;
  58
  59	s1 = module->name;
  60	s2 = slots[idx];
  61	if (*s2 == '!') {
  62		match = 0; /* negative match */
  63		s2++;
  64	}
  65	/* compare module name strings
  66	 * hyphens are handled as equivalent with underscore
  67	 */
  68	for (;;) {
  69		char c1 = *s1++;
  70		char c2 = *s2++;
  71		if (c1 == '-')
  72			c1 = '_';
  73		if (c2 == '-')
  74			c2 = '_';
  75		if (c1 != c2)
  76			return !match;
  77		if (!c1)
  78			break;
  79	}
  80#endif /* CONFIG_MODULES */
  81	return match;
  82}
  83
  84#if IS_ENABLED(CONFIG_SND_MIXER_OSS)
  85int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int free_flag);
  86EXPORT_SYMBOL(snd_mixer_oss_notify_callback);
  87#endif
  88
  89static int check_empty_slot(struct module *module, int slot)
  90{
  91	return !slots[slot] || !*slots[slot];
  92}
  93
  94/* return an empty slot number (>= 0) found in the given bitmask @mask.
  95 * @mask == -1 == 0xffffffff means: take any free slot up to 32
  96 * when no slot is available, return the original @mask as is.
  97 */
  98static int get_slot_from_bitmask(int mask, int (*check)(struct module *, int),
  99				 struct module *module)
 100{
 101	int slot;
 102
 103	for (slot = 0; slot < SNDRV_CARDS; slot++) {
 104		if (slot < 32 && !(mask & (1U << slot)))
 105			continue;
 106		if (!test_bit(slot, snd_cards_lock)) {
 107			if (check(module, slot))
 108				return slot; /* found */
 109		}
 110	}
 111	return mask; /* unchanged */
 112}
 113
 114/* the default release callback set in snd_device_alloc() */
 115static void default_release_alloc(struct device *dev)
 116{
 117	kfree(dev);
 118}
 119
 120/**
 121 * snd_device_alloc - Allocate and initialize struct device for sound devices
 122 * @dev_p: pointer to store the allocated device
 123 * @card: card to assign, optional
 124 *
 125 * For releasing the allocated device, call put_device().
 126 */
 127int snd_device_alloc(struct device **dev_p, struct snd_card *card)
 128{
 129	struct device *dev;
 130
 131	*dev_p = NULL;
 132	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 133	if (!dev)
 134		return -ENOMEM;
 135	device_initialize(dev);
 136	if (card)
 137		dev->parent = &card->card_dev;
 138	dev->class = &sound_class;
 139	dev->release = default_release_alloc;
 140	*dev_p = dev;
 141	return 0;
 142}
 143EXPORT_SYMBOL_GPL(snd_device_alloc);
 144
 145static int snd_card_init(struct snd_card *card, struct device *parent,
 146			 int idx, const char *xid, struct module *module,
 147			 size_t extra_size);
 148static int snd_card_do_free(struct snd_card *card);
 149static const struct attribute_group card_dev_attr_group;
 150
 151static void release_card_device(struct device *dev)
 152{
 153	snd_card_do_free(dev_to_snd_card(dev));
 154}
 155
 156/**
 157 *  snd_card_new - create and initialize a soundcard structure
 158 *  @parent: the parent device object
 159 *  @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
 160 *  @xid: card identification (ASCII string)
 161 *  @module: top level module for locking
 162 *  @extra_size: allocate this extra size after the main soundcard structure
 163 *  @card_ret: the pointer to store the created card instance
 164 *
 165 *  The function allocates snd_card instance via kzalloc with the given
 166 *  space for the driver to use freely.  The allocated struct is stored
 167 *  in the given card_ret pointer.
 168 *
 169 *  Return: Zero if successful or a negative error code.
 170 */
 171int snd_card_new(struct device *parent, int idx, const char *xid,
 172		    struct module *module, int extra_size,
 173		    struct snd_card **card_ret)
 174{
 175	struct snd_card *card;
 176	int err;
 177
 178	if (snd_BUG_ON(!card_ret))
 179		return -EINVAL;
 180	*card_ret = NULL;
 181
 182	if (extra_size < 0)
 183		extra_size = 0;
 184	card = kzalloc(sizeof(*card) + extra_size, GFP_KERNEL);
 185	if (!card)
 186		return -ENOMEM;
 187
 188	err = snd_card_init(card, parent, idx, xid, module, extra_size);
 189	if (err < 0)
 190		return err; /* card is freed by error handler */
 191
 192	*card_ret = card;
 193	return 0;
 194}
 195EXPORT_SYMBOL(snd_card_new);
 196
 197static void __snd_card_release(struct device *dev, void *data)
 198{
 199	snd_card_free(data);
 200}
 201
 202/**
 203 * snd_devm_card_new - managed snd_card object creation
 204 * @parent: the parent device object
 205 * @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
 206 * @xid: card identification (ASCII string)
 207 * @module: top level module for locking
 208 * @extra_size: allocate this extra size after the main soundcard structure
 209 * @card_ret: the pointer to store the created card instance
 210 *
 211 * This function works like snd_card_new() but manages the allocated resource
 212 * via devres, i.e. you don't need to free explicitly.
 213 *
 214 * When a snd_card object is created with this function and registered via
 215 * snd_card_register(), the very first devres action to call snd_card_free()
 216 * is added automatically.  In that way, the resource disconnection is assured
 217 * at first, then released in the expected order.
 218 *
 219 * If an error happens at the probe before snd_card_register() is called and
 220 * there have been other devres resources, you'd need to free the card manually
 221 * via snd_card_free() call in the error; otherwise it may lead to UAF due to
 222 * devres call orders.  You can use snd_card_free_on_error() helper for
 223 * handling it more easily.
 224 *
 225 * Return: zero if successful, or a negative error code
 226 */
 227int snd_devm_card_new(struct device *parent, int idx, const char *xid,
 228		      struct module *module, size_t extra_size,
 229		      struct snd_card **card_ret)
 230{
 231	struct snd_card *card;
 232	int err;
 233
 234	*card_ret = NULL;
 235	card = devres_alloc(__snd_card_release, sizeof(*card) + extra_size,
 236			    GFP_KERNEL);
 237	if (!card)
 238		return -ENOMEM;
 239	card->managed = true;
 240	err = snd_card_init(card, parent, idx, xid, module, extra_size);
 241	if (err < 0) {
 242		devres_free(card); /* in managed mode, we need to free manually */
 243		return err;
 244	}
 245
 246	devres_add(parent, card);
 247	*card_ret = card;
 248	return 0;
 249}
 250EXPORT_SYMBOL_GPL(snd_devm_card_new);
 251
 252/**
 253 * snd_card_free_on_error - a small helper for handling devm probe errors
 254 * @dev: the managed device object
 255 * @ret: the return code from the probe callback
 256 *
 257 * This function handles the explicit snd_card_free() call at the error from
 258 * the probe callback.  It's just a small helper for simplifying the error
 259 * handling with the managed devices.
 260 *
 261 * Return: zero if successful, or a negative error code
 262 */
 263int snd_card_free_on_error(struct device *dev, int ret)
 264{
 265	struct snd_card *card;
 266
 267	if (!ret)
 268		return 0;
 269	card = devres_find(dev, __snd_card_release, NULL, NULL);
 270	if (card)
 271		snd_card_free(card);
 272	return ret;
 273}
 274EXPORT_SYMBOL_GPL(snd_card_free_on_error);
 275
 276static int snd_card_init(struct snd_card *card, struct device *parent,
 277			 int idx, const char *xid, struct module *module,
 278			 size_t extra_size)
 279{
 280	int err;
 281
 282	if (extra_size > 0)
 283		card->private_data = (char *)card + sizeof(struct snd_card);
 284	if (xid)
 285		strscpy(card->id, xid, sizeof(card->id));
 286	err = 0;
 287	scoped_guard(mutex, &snd_card_mutex) {
 288		if (idx < 0) /* first check the matching module-name slot */
 289			idx = get_slot_from_bitmask(idx, module_slot_match, module);
 290		if (idx < 0) /* if not matched, assign an empty slot */
 291			idx = get_slot_from_bitmask(idx, check_empty_slot, module);
 292		if (idx < 0)
 293			err = -ENODEV;
 294		else if (idx < snd_ecards_limit) {
 295			if (test_bit(idx, snd_cards_lock))
 296				err = -EBUSY;	/* invalid */
 297		} else if (idx >= SNDRV_CARDS)
 298			err = -ENODEV;
 299		if (!err) {
 300			set_bit(idx, snd_cards_lock);		/* lock it */
 301			if (idx >= snd_ecards_limit)
 302				snd_ecards_limit = idx + 1; /* increase the limit */
 303		}
 304	}
 305	if (err < 0) {
 306		dev_err(parent, "cannot find the slot for index %d (range 0-%i), error: %d\n",
 307			idx, snd_ecards_limit - 1, err);
 308		if (!card->managed)
 309			kfree(card); /* manually free here, as no destructor called */
 310		return err;
 311	}
 312	card->dev = parent;
 313	card->number = idx;
 314	WARN_ON(IS_MODULE(CONFIG_SND) && !module);
 315	card->module = module;
 316	INIT_LIST_HEAD(&card->devices);
 317	init_rwsem(&card->controls_rwsem);
 318	rwlock_init(&card->controls_rwlock);
 319	INIT_LIST_HEAD(&card->controls);
 320	INIT_LIST_HEAD(&card->ctl_files);
 321#ifdef CONFIG_SND_CTL_FAST_LOOKUP
 322	xa_init(&card->ctl_numids);
 323	xa_init(&card->ctl_hash);
 324#endif
 325	spin_lock_init(&card->files_lock);
 326	INIT_LIST_HEAD(&card->files_list);
 327	mutex_init(&card->memory_mutex);
 328#ifdef CONFIG_PM
 329	init_waitqueue_head(&card->power_sleep);
 330	init_waitqueue_head(&card->power_ref_sleep);
 331	atomic_set(&card->power_ref, 0);
 332#endif
 333	init_waitqueue_head(&card->remove_sleep);
 334	card->sync_irq = -1;
 335
 336	device_initialize(&card->card_dev);
 337	card->card_dev.parent = parent;
 338	card->card_dev.class = &sound_class;
 339	card->card_dev.release = release_card_device;
 340	card->card_dev.groups = card->dev_groups;
 341	card->dev_groups[0] = &card_dev_attr_group;
 342	err = kobject_set_name(&card->card_dev.kobj, "card%d", idx);
 343	if (err < 0)
 344		goto __error;
 345
 346	snprintf(card->irq_descr, sizeof(card->irq_descr), "%s:%s",
 347		 dev_driver_string(card->dev), dev_name(&card->card_dev));
 348
 349	/* the control interface cannot be accessed from the user space until */
 350	/* snd_cards_bitmask and snd_cards are set with snd_card_register */
 351	err = snd_ctl_create(card);
 352	if (err < 0) {
 353		dev_err(parent, "unable to register control minors\n");
 354		goto __error;
 355	}
 356	err = snd_info_card_create(card);
 357	if (err < 0) {
 358		dev_err(parent, "unable to create card info\n");
 359		goto __error_ctl;
 360	}
 361
 362#ifdef CONFIG_SND_DEBUG
 363	card->debugfs_root = debugfs_create_dir(dev_name(&card->card_dev),
 364						sound_debugfs_root);
 365#endif
 366	return 0;
 367
 368      __error_ctl:
 369	snd_device_free_all(card);
 370      __error:
 371	put_device(&card->card_dev);
 372  	return err;
 373}
 374
 375/**
 376 * snd_card_ref - Get the card object from the index
 377 * @idx: the card index
 378 *
 379 * Returns a card object corresponding to the given index or NULL if not found.
 380 * Release the object via snd_card_unref().
 381 *
 382 * Return: a card object or NULL
 383 */
 384struct snd_card *snd_card_ref(int idx)
 385{
 386	struct snd_card *card;
 387
 388	guard(mutex)(&snd_card_mutex);
 389	card = snd_cards[idx];
 390	if (card)
 391		get_device(&card->card_dev);
 392	return card;
 393}
 394EXPORT_SYMBOL_GPL(snd_card_ref);
 395
 396/* return non-zero if a card is already locked */
 397int snd_card_locked(int card)
 398{
 399	guard(mutex)(&snd_card_mutex);
 400	return test_bit(card, snd_cards_lock);
 401}
 402
 403static loff_t snd_disconnect_llseek(struct file *file, loff_t offset, int orig)
 404{
 405	return -ENODEV;
 406}
 407
 408static ssize_t snd_disconnect_read(struct file *file, char __user *buf,
 409				   size_t count, loff_t *offset)
 410{
 411	return -ENODEV;
 412}
 413
 414static ssize_t snd_disconnect_write(struct file *file, const char __user *buf,
 415				    size_t count, loff_t *offset)
 416{
 417	return -ENODEV;
 418}
 419
 420static int snd_disconnect_release(struct inode *inode, struct file *file)
 421{
 422	struct snd_monitor_file *df = NULL, *_df;
 423
 424	scoped_guard(spinlock, &shutdown_lock) {
 425		list_for_each_entry(_df, &shutdown_files, shutdown_list) {
 426			if (_df->file == file) {
 427				df = _df;
 428				list_del_init(&df->shutdown_list);
 429				break;
 430			}
 431		}
 432	}
 433
 434	if (likely(df)) {
 435		if ((file->f_flags & FASYNC) && df->disconnected_f_op->fasync)
 436			df->disconnected_f_op->fasync(-1, file, 0);
 437		return df->disconnected_f_op->release(inode, file);
 438	}
 439
 440	panic("%s(%p, %p) failed!", __func__, inode, file);
 441}
 442
 443static __poll_t snd_disconnect_poll(struct file * file, poll_table * wait)
 444{
 445	return EPOLLERR | EPOLLNVAL;
 446}
 447
 448static long snd_disconnect_ioctl(struct file *file,
 449				 unsigned int cmd, unsigned long arg)
 450{
 451	return -ENODEV;
 452}
 453
 454static int snd_disconnect_mmap(struct file *file, struct vm_area_struct *vma)
 455{
 456	return -ENODEV;
 457}
 458
 459static int snd_disconnect_fasync(int fd, struct file *file, int on)
 460{
 461	return -ENODEV;
 462}
 463
 464static const struct file_operations snd_shutdown_f_ops =
 465{
 466	.owner = 	THIS_MODULE,
 467	.llseek =	snd_disconnect_llseek,
 468	.read = 	snd_disconnect_read,
 469	.write =	snd_disconnect_write,
 470	.release =	snd_disconnect_release,
 471	.poll =		snd_disconnect_poll,
 472	.unlocked_ioctl = snd_disconnect_ioctl,
 473#ifdef CONFIG_COMPAT
 474	.compat_ioctl = snd_disconnect_ioctl,
 475#endif
 476	.mmap =		snd_disconnect_mmap,
 477	.fasync =	snd_disconnect_fasync
 478};
 479
 480/**
 481 *  snd_card_disconnect - disconnect all APIs from the file-operations (user space)
 482 *  @card: soundcard structure
 483 *
 484 *  Disconnects all APIs from the file-operations (user space).
 485 *
 486 *  Return: Zero, otherwise a negative error code.
 487 *
 488 *  Note: The current implementation replaces all active file->f_op with special
 489 *        dummy file operations (they do nothing except release).
 490 */
 491void snd_card_disconnect(struct snd_card *card)
 492{
 493	struct snd_monitor_file *mfile;
 494
 495	if (!card)
 496		return;
 497
 498	scoped_guard(spinlock, &card->files_lock) {
 499		if (card->shutdown)
 500			return;
 501		card->shutdown = 1;
 502
 503		/* replace file->f_op with special dummy operations */
 504		list_for_each_entry(mfile, &card->files_list, list) {
 505			/* it's critical part, use endless loop */
 506			/* we have no room to fail */
 507			mfile->disconnected_f_op = mfile->file->f_op;
 508
 509			scoped_guard(spinlock, &shutdown_lock)
 510				list_add(&mfile->shutdown_list, &shutdown_files);
 511
 512			mfile->file->f_op = &snd_shutdown_f_ops;
 513			fops_get(mfile->file->f_op);
 514		}
 515	}
 516
 517#ifdef CONFIG_PM
 518	/* wake up sleepers here before other callbacks for avoiding potential
 519	 * deadlocks with other locks (e.g. in kctls);
 520	 * then this notifies the shutdown and sleepers would abort immediately
 521	 */
 522	wake_up_all(&card->power_sleep);
 523#endif
 524
 525	/* notify all connected devices about disconnection */
 526	/* at this point, they cannot respond to any calls except release() */
 527
 528#if IS_ENABLED(CONFIG_SND_MIXER_OSS)
 529	if (snd_mixer_oss_notify_callback)
 530		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_DISCONNECT);
 531#endif
 532
 533	/* notify all devices that we are disconnected */
 534	snd_device_disconnect_all(card);
 535
 536	if (card->sync_irq > 0)
 537		synchronize_irq(card->sync_irq);
 538
 539	snd_info_card_disconnect(card);
 540#ifdef CONFIG_SND_DEBUG
 541	debugfs_remove(card->debugfs_root);
 542	card->debugfs_root = NULL;
 543#endif
 544
 545	if (card->registered) {
 546		device_del(&card->card_dev);
 547		card->registered = false;
 548	}
 549
 550	/* disable fops (user space) operations for ALSA API */
 551	scoped_guard(mutex, &snd_card_mutex) {
 552		snd_cards[card->number] = NULL;
 553		clear_bit(card->number, snd_cards_lock);
 554	}
 555
 556	snd_power_sync_ref(card);
 557}
 558EXPORT_SYMBOL(snd_card_disconnect);
 559
 560/**
 561 * snd_card_disconnect_sync - disconnect card and wait until files get closed
 562 * @card: card object to disconnect
 563 *
 564 * This calls snd_card_disconnect() for disconnecting all belonging components
 565 * and waits until all pending files get closed.
 566 * It assures that all accesses from user-space finished so that the driver
 567 * can release its resources gracefully.
 568 */
 569void snd_card_disconnect_sync(struct snd_card *card)
 570{
 571	snd_card_disconnect(card);
 572
 573	guard(spinlock_irq)(&card->files_lock);
 574	wait_event_lock_irq(card->remove_sleep,
 575			    list_empty(&card->files_list),
 576			    card->files_lock);
 577}
 578EXPORT_SYMBOL_GPL(snd_card_disconnect_sync);
 579
 580static int snd_card_do_free(struct snd_card *card)
 581{
 582	card->releasing = true;
 583#if IS_ENABLED(CONFIG_SND_MIXER_OSS)
 584	if (snd_mixer_oss_notify_callback)
 585		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE);
 586#endif
 587	snd_device_free_all(card);
 588	if (card->private_free)
 589		card->private_free(card);
 590	if (snd_info_card_free(card) < 0) {
 591		dev_warn(card->dev, "unable to free card info\n");
 592		/* Not fatal error */
 593	}
 594	if (card->release_completion)
 595		complete(card->release_completion);
 596	if (!card->managed)
 597		kfree(card);
 598	return 0;
 599}
 600
 601/**
 602 * snd_card_free_when_closed - Disconnect the card, free it later eventually
 603 * @card: soundcard structure
 604 *
 605 * Unlike snd_card_free(), this function doesn't try to release the card
 606 * resource immediately, but tries to disconnect at first.  When the card
 607 * is still in use, the function returns before freeing the resources.
 608 * The card resources will be freed when the refcount gets to zero.
 609 *
 610 * Return: zero if successful, or a negative error code
 611 */
 612void snd_card_free_when_closed(struct snd_card *card)
 613{
 614	if (!card)
 615		return;
 616
 617	snd_card_disconnect(card);
 618	put_device(&card->card_dev);
 619	return;
 620}
 621EXPORT_SYMBOL(snd_card_free_when_closed);
 622
 623/**
 624 * snd_card_free - frees given soundcard structure
 625 * @card: soundcard structure
 626 *
 627 * This function releases the soundcard structure and the all assigned
 628 * devices automatically.  That is, you don't have to release the devices
 629 * by yourself.
 630 *
 631 * This function waits until the all resources are properly released.
 632 *
 633 * Return: Zero. Frees all associated devices and frees the control
 634 * interface associated to given soundcard.
 635 */
 636void snd_card_free(struct snd_card *card)
 637{
 638	DECLARE_COMPLETION_ONSTACK(released);
 639
 640	/* The call of snd_card_free() is allowed from various code paths;
 641	 * a manual call from the driver and the call via devres_free, and
 642	 * we need to avoid double-free. Moreover, the release via devres
 643	 * may call snd_card_free() twice due to its nature, we need to have
 644	 * the check here at the beginning.
 645	 */
 646	if (card->releasing)
 647		return;
 648
 649	card->release_completion = &released;
 650	snd_card_free_when_closed(card);
 651
 652	/* wait, until all devices are ready for the free operation */
 653	wait_for_completion(&released);
 654}
 655EXPORT_SYMBOL(snd_card_free);
 656
 657/* check, if the character is in the valid ASCII range */
 658static inline bool safe_ascii_char(char c)
 659{
 660	return isascii(c) && isalnum(c);
 661}
 662
 663/* retrieve the last word of shortname or longname */
 664static const char *retrieve_id_from_card_name(const char *name)
 665{
 666	const char *spos = name;
 667
 668	while (*name) {
 669		if (isspace(*name) && safe_ascii_char(name[1]))
 670			spos = name + 1;
 671		name++;
 672	}
 673	return spos;
 674}
 675
 676/* return true if the given id string doesn't conflict any other card ids */
 677static bool card_id_ok(struct snd_card *card, const char *id)
 678{
 679	int i;
 680	if (!snd_info_check_reserved_words(id))
 681		return false;
 682	for (i = 0; i < snd_ecards_limit; i++) {
 683		if (snd_cards[i] && snd_cards[i] != card &&
 684		    !strcmp(snd_cards[i]->id, id))
 685			return false;
 686	}
 687	return true;
 688}
 689
 690/* copy to card->id only with valid letters from nid */
 691static void copy_valid_id_string(struct snd_card *card, const char *src,
 692				 const char *nid)
 693{
 694	char *id = card->id;
 695
 696	while (*nid && !safe_ascii_char(*nid))
 697		nid++;
 698	if (isdigit(*nid))
 699		*id++ = isalpha(*src) ? *src : 'D';
 700	while (*nid && (size_t)(id - card->id) < sizeof(card->id) - 1) {
 701		if (safe_ascii_char(*nid))
 702			*id++ = *nid;
 703		nid++;
 704	}
 705	*id = 0;
 706}
 707
 708/* Set card->id from the given string
 709 * If the string conflicts with other ids, add a suffix to make it unique.
 710 */
 711static void snd_card_set_id_no_lock(struct snd_card *card, const char *src,
 712				    const char *nid)
 713{
 714	int len, loops;
 715	bool is_default = false;
 716	char *id;
 717	
 718	copy_valid_id_string(card, src, nid);
 719	id = card->id;
 720
 721 again:
 722	/* use "Default" for obviously invalid strings
 723	 * ("card" conflicts with proc directories)
 724	 */
 725	if (!*id || !strncmp(id, "card", 4)) {
 726		strscpy(card->id, "Default");
 727		is_default = true;
 728	}
 729
 730	len = strlen(id);
 731	for (loops = 0; loops < SNDRV_CARDS; loops++) {
 732		char sfxstr[5]; /* "_012" */
 733		int sfxlen, slen;
 734
 735		if (card_id_ok(card, id))
 736			return; /* OK */
 737
 738		/* Add _XYZ suffix */
 739		sfxlen = scnprintf(sfxstr, sizeof(sfxstr), "_%X", loops + 1);
 740		if (len + sfxlen >= sizeof(card->id))
 741			slen = sizeof(card->id) - sfxlen - 1;
 742		else
 743			slen = len;
 744		strscpy(id + slen, sfxstr, sizeof(card->id) - slen);
 745	}
 746	/* fallback to the default id */
 747	if (!is_default) {
 748		*id = 0;
 749		goto again;
 750	}
 751	/* last resort... */
 752	dev_err(card->dev, "unable to set card id (%s)\n", id);
 753	if (card->proc_root->name)
 754		strscpy(card->id, card->proc_root->name, sizeof(card->id));
 755}
 756
 757/**
 758 *  snd_card_set_id - set card identification name
 759 *  @card: soundcard structure
 760 *  @nid: new identification string
 761 *
 762 *  This function sets the card identification and checks for name
 763 *  collisions.
 764 */
 765void snd_card_set_id(struct snd_card *card, const char *nid)
 766{
 767	/* check if user specified own card->id */
 768	if (card->id[0] != '\0')
 769		return;
 770	guard(mutex)(&snd_card_mutex);
 771	snd_card_set_id_no_lock(card, nid, nid);
 772}
 773EXPORT_SYMBOL(snd_card_set_id);
 774
 775static ssize_t id_show(struct device *dev,
 776		       struct device_attribute *attr, char *buf)
 777{
 778	struct snd_card *card = container_of(dev, struct snd_card, card_dev);
 779	return sysfs_emit(buf, "%s\n", card->id);
 780}
 781
 782static ssize_t id_store(struct device *dev, struct device_attribute *attr,
 783			const char *buf, size_t count)
 784{
 785	struct snd_card *card = container_of(dev, struct snd_card, card_dev);
 786	char buf1[sizeof(card->id)];
 787	size_t copy = count > sizeof(card->id) - 1 ?
 788					sizeof(card->id) - 1 : count;
 789	size_t idx;
 790	int c;
 791
 792	for (idx = 0; idx < copy; idx++) {
 793		c = buf[idx];
 794		if (!safe_ascii_char(c) && c != '_' && c != '-')
 795			return -EINVAL;
 796	}
 797	memcpy(buf1, buf, copy);
 798	buf1[copy] = '\0';
 799	guard(mutex)(&snd_card_mutex);
 800	if (!card_id_ok(NULL, buf1))
 801		return -EEXIST;
 802	strscpy(card->id, buf1);
 803	snd_info_card_id_change(card);
 804
 805	return count;
 806}
 807
 808static DEVICE_ATTR_RW(id);
 809
 810static ssize_t number_show(struct device *dev,
 811			   struct device_attribute *attr, char *buf)
 812{
 813	struct snd_card *card = container_of(dev, struct snd_card, card_dev);
 814	return sysfs_emit(buf, "%i\n", card->number);
 815}
 816
 817static DEVICE_ATTR_RO(number);
 818
 819static struct attribute *card_dev_attrs[] = {
 820	&dev_attr_id.attr,
 821	&dev_attr_number.attr,
 822	NULL
 823};
 824
 825static const struct attribute_group card_dev_attr_group = {
 826	.attrs	= card_dev_attrs,
 827};
 828
 829/**
 830 * snd_card_add_dev_attr - Append a new sysfs attribute group to card
 831 * @card: card instance
 832 * @group: attribute group to append
 833 *
 834 * Return: zero if successful, or a negative error code
 835 */
 836int snd_card_add_dev_attr(struct snd_card *card,
 837			  const struct attribute_group *group)
 838{
 839	int i;
 840
 841	/* loop for (arraysize-1) here to keep NULL at the last entry */
 842	for (i = 0; i < ARRAY_SIZE(card->dev_groups) - 1; i++) {
 843		if (!card->dev_groups[i]) {
 844			card->dev_groups[i] = group;
 845			return 0;
 846		}
 847	}
 848
 849	dev_err(card->dev, "Too many groups assigned\n");
 850	return -ENOSPC;
 851}
 852EXPORT_SYMBOL_GPL(snd_card_add_dev_attr);
 853
 854static void trigger_card_free(void *data)
 855{
 856	snd_card_free(data);
 857}
 858
 859/**
 860 *  snd_card_register - register the soundcard
 861 *  @card: soundcard structure
 862 *
 863 *  This function registers all the devices assigned to the soundcard.
 864 *  Until calling this, the ALSA control interface is blocked from the
 865 *  external accesses.  Thus, you should call this function at the end
 866 *  of the initialization of the card.
 867 *
 868 *  Return: Zero otherwise a negative error code if the registration failed.
 869 */
 870int snd_card_register(struct snd_card *card)
 871{
 872	int err;
 873
 874	if (snd_BUG_ON(!card))
 875		return -EINVAL;
 876
 877	if (!card->registered) {
 878		err = device_add(&card->card_dev);
 879		if (err < 0)
 880			return err;
 881		card->registered = true;
 882	} else {
 883		if (card->managed)
 884			devm_remove_action(card->dev, trigger_card_free, card);
 885	}
 886
 887	if (card->managed) {
 888		err = devm_add_action(card->dev, trigger_card_free, card);
 889		if (err < 0)
 890			return err;
 891	}
 892
 893	err = snd_device_register_all(card);
 894	if (err < 0)
 895		return err;
 896	scoped_guard(mutex, &snd_card_mutex) {
 897		if (snd_cards[card->number]) {
 898			/* already registered */
 899			return snd_info_card_register(card); /* register pending info */
 900		}
 901		if (*card->id) {
 902			/* make a unique id name from the given string */
 903			char tmpid[sizeof(card->id)];
 904
 905			memcpy(tmpid, card->id, sizeof(card->id));
 906			snd_card_set_id_no_lock(card, tmpid, tmpid);
 907		} else {
 908			/* create an id from either shortname or longname */
 909			const char *src;
 910
 911			src = *card->shortname ? card->shortname : card->longname;
 912			snd_card_set_id_no_lock(card, src,
 913						retrieve_id_from_card_name(src));
 914		}
 915		snd_cards[card->number] = card;
 916	}
 917	err = snd_info_card_register(card);
 918	if (err < 0)
 919		return err;
 920
 921#if IS_ENABLED(CONFIG_SND_MIXER_OSS)
 922	if (snd_mixer_oss_notify_callback)
 923		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_REGISTER);
 924#endif
 925	return 0;
 926}
 927EXPORT_SYMBOL(snd_card_register);
 928
 929#ifdef CONFIG_SND_PROC_FS
 930static void snd_card_info_read(struct snd_info_entry *entry,
 931			       struct snd_info_buffer *buffer)
 932{
 933	int idx, count;
 934	struct snd_card *card;
 935
 936	for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
 937		guard(mutex)(&snd_card_mutex);
 938		card = snd_cards[idx];
 939		if (card) {
 940			count++;
 941			snd_iprintf(buffer, "%2i [%-15s]: %s - %s\n",
 942					idx,
 943					card->id,
 944					card->driver,
 945					card->shortname);
 946			snd_iprintf(buffer, "                      %s\n",
 947					card->longname);
 948		}
 949	}
 950	if (!count)
 951		snd_iprintf(buffer, "--- no soundcards ---\n");
 952}
 953
 954#ifdef CONFIG_SND_OSSEMUL
 955void snd_card_info_read_oss(struct snd_info_buffer *buffer)
 956{
 957	int idx, count;
 958	struct snd_card *card;
 959
 960	for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
 961		guard(mutex)(&snd_card_mutex);
 962		card = snd_cards[idx];
 963		if (card) {
 964			count++;
 965			snd_iprintf(buffer, "%s\n", card->longname);
 966		}
 967	}
 968	if (!count) {
 969		snd_iprintf(buffer, "--- no soundcards ---\n");
 970	}
 971}
 972
 973#endif
 974
 975#ifdef CONFIG_MODULES
 976static void snd_card_module_info_read(struct snd_info_entry *entry,
 977				      struct snd_info_buffer *buffer)
 978{
 979	int idx;
 980	struct snd_card *card;
 981
 982	for (idx = 0; idx < SNDRV_CARDS; idx++) {
 983		guard(mutex)(&snd_card_mutex);
 984		card = snd_cards[idx];
 985		if (card)
 986			snd_iprintf(buffer, "%2i %s\n",
 987				    idx, card->module->name);
 988	}
 989}
 990#endif
 991
 992int __init snd_card_info_init(void)
 993{
 994	struct snd_info_entry *entry;
 995
 996	entry = snd_info_create_module_entry(THIS_MODULE, "cards", NULL);
 997	if (! entry)
 998		return -ENOMEM;
 999	entry->c.text.read = snd_card_info_read;
1000	if (snd_info_register(entry) < 0)
1001		return -ENOMEM; /* freed in error path */
1002
1003#ifdef CONFIG_MODULES
1004	entry = snd_info_create_module_entry(THIS_MODULE, "modules", NULL);
1005	if (!entry)
1006		return -ENOMEM;
1007	entry->c.text.read = snd_card_module_info_read;
1008	if (snd_info_register(entry) < 0)
1009		return -ENOMEM; /* freed in error path */
1010#endif
1011
1012	return 0;
1013}
1014#endif /* CONFIG_SND_PROC_FS */
1015
1016/**
1017 *  snd_component_add - add a component string
1018 *  @card: soundcard structure
1019 *  @component: the component id string
1020 *
1021 *  This function adds the component id string to the supported list.
1022 *  The component can be referred from the alsa-lib.
1023 *
1024 *  Return: Zero otherwise a negative error code.
1025 */
1026  
1027int snd_component_add(struct snd_card *card, const char *component)
1028{
1029	char *ptr;
1030	int len = strlen(component);
1031
1032	ptr = strstr(card->components, component);
1033	if (ptr != NULL) {
1034		if (ptr[len] == '\0' || ptr[len] == ' ')	/* already there */
1035			return 1;
1036	}
1037	if (strlen(card->components) + 1 + len + 1 > sizeof(card->components)) {
1038		snd_BUG();
1039		return -ENOMEM;
1040	}
1041	if (card->components[0] != '\0')
1042		strcat(card->components, " ");
1043	strcat(card->components, component);
1044	return 0;
1045}
1046EXPORT_SYMBOL(snd_component_add);
1047
1048/**
1049 *  snd_card_file_add - add the file to the file list of the card
1050 *  @card: soundcard structure
1051 *  @file: file pointer
1052 *
1053 *  This function adds the file to the file linked-list of the card.
1054 *  This linked-list is used to keep tracking the connection state,
1055 *  and to avoid the release of busy resources by hotplug.
1056 *
1057 *  Return: zero or a negative error code.
1058 */
1059int snd_card_file_add(struct snd_card *card, struct file *file)
1060{
1061	struct snd_monitor_file *mfile;
1062
1063	mfile = kmalloc(sizeof(*mfile), GFP_KERNEL);
1064	if (mfile == NULL)
1065		return -ENOMEM;
1066	mfile->file = file;
1067	mfile->disconnected_f_op = NULL;
1068	INIT_LIST_HEAD(&mfile->shutdown_list);
1069	guard(spinlock)(&card->files_lock);
1070	if (card->shutdown) {
1071		kfree(mfile);
1072		return -ENODEV;
1073	}
1074	list_add(&mfile->list, &card->files_list);
1075	get_device(&card->card_dev);
1076	return 0;
1077}
1078EXPORT_SYMBOL(snd_card_file_add);
1079
1080/**
1081 *  snd_card_file_remove - remove the file from the file list
1082 *  @card: soundcard structure
1083 *  @file: file pointer
1084 *
1085 *  This function removes the file formerly added to the card via
1086 *  snd_card_file_add() function.
1087 *  If all files are removed and snd_card_free_when_closed() was
1088 *  called beforehand, it processes the pending release of
1089 *  resources.
1090 *
1091 *  Return: Zero or a negative error code.
1092 */
1093int snd_card_file_remove(struct snd_card *card, struct file *file)
1094{
1095	struct snd_monitor_file *mfile, *found = NULL;
1096
1097	scoped_guard(spinlock, &card->files_lock) {
1098		list_for_each_entry(mfile, &card->files_list, list) {
1099			if (mfile->file == file) {
1100				list_del(&mfile->list);
1101				scoped_guard(spinlock, &shutdown_lock)
1102					list_del(&mfile->shutdown_list);
1103				if (mfile->disconnected_f_op)
1104					fops_put(mfile->disconnected_f_op);
1105				found = mfile;
1106				break;
1107			}
1108		}
1109		if (list_empty(&card->files_list))
1110			wake_up_all(&card->remove_sleep);
1111	}
1112	if (!found) {
1113		dev_err(card->dev, "card file remove problem (%p)\n", file);
1114		return -ENOENT;
1115	}
1116	kfree(found);
1117	put_device(&card->card_dev);
1118	return 0;
1119}
1120EXPORT_SYMBOL(snd_card_file_remove);
1121
1122#ifdef CONFIG_PM
1123/**
1124 * snd_power_ref_and_wait - wait until the card gets powered up
1125 * @card: soundcard structure
1126 *
1127 * Take the power_ref reference count of the given card, and
1128 * wait until the card gets powered up to SNDRV_CTL_POWER_D0 state.
1129 * The refcount is down again while sleeping until power-up, hence this
1130 * function can be used for syncing the floating control ops accesses,
1131 * typically around calling control ops.
1132 *
1133 * The caller needs to pull down the refcount via snd_power_unref() later
1134 * no matter whether the error is returned from this function or not.
1135 *
1136 * Return: Zero if successful, or a negative error code.
1137 */
1138int snd_power_ref_and_wait(struct snd_card *card)
1139{
1140	snd_power_ref(card);
1141	if (snd_power_get_state(card) == SNDRV_CTL_POWER_D0)
1142		return 0;
1143	wait_event_cmd(card->power_sleep,
1144		       card->shutdown ||
1145		       snd_power_get_state(card) == SNDRV_CTL_POWER_D0,
1146		       snd_power_unref(card), snd_power_ref(card));
1147	return card->shutdown ? -ENODEV : 0;
1148}
1149EXPORT_SYMBOL_GPL(snd_power_ref_and_wait);
1150
1151/**
1152 * snd_power_wait - wait until the card gets powered up (old form)
1153 * @card: soundcard structure
1154 *
1155 * Wait until the card gets powered up to SNDRV_CTL_POWER_D0 state.
1156 *
1157 * Return: Zero if successful, or a negative error code.
1158 */
1159int snd_power_wait(struct snd_card *card)
1160{
1161	int ret;
1162
1163	ret = snd_power_ref_and_wait(card);
1164	snd_power_unref(card);
1165	return ret;
1166}
1167EXPORT_SYMBOL(snd_power_wait);
1168#endif /* CONFIG_PM */