init.c

linux 内核源代码

/*
 *  Initialization routines
 *  Copyright (c) by Jaroslav Kysela <[e-mail]>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <sound/driver.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/ctype.h>
#include <linux/pm.h>

#include <sound/core.h>
#include <sound/control.h>
#include <sound/info.h>

static DEFINE_SPINLOCK(shutdown_lock);
static LIST_HEAD(shutdown_files);

static const struct file_operations snd_shutdown_f_ops;

static unsigned int snd_cards_lock;	/* locked for registering/using */
struct snd_card *snd_cards[SNDRV_CARDS];
EXPORT_SYMBOL(snd_cards);

static DEFINE_MUTEX(snd_card_mutex);

#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int free_flag);
EXPORT_SYMBOL(snd_mixer_oss_notify_callback);
#endif

#ifdef CONFIG_PROC_FS
static void snd_card_id_read(struct snd_info_entry *entry,
			     struct snd_info_buffer *buffer)
{
	snd_iprintf(buffer, "%s\n", entry->card->id);
}

static inline int init_info_for_card(struct snd_card *card)
{
	int err;
	struct snd_info_entry *entry;

	if ((err = snd_info_card_register(card)) < 0) {
		snd_printd("unable to create card info\n");
		return err;
	}
	if ((entry = snd_info_create_card_entry(card, "id", card->proc_root)) == NULL) {
		snd_printd("unable to create card entry\n");
		return err;
	}
	entry->c.text.read = snd_card_id_read;
	if (snd_info_register(entry) < 0) {
		snd_info_free_entry(entry);
		entry = NULL;
	}
	card->proc_id = entry;
	return 0;
}
#else /* !CONFIG_PROC_FS */
#define init_info_for_card(card)
#endif

/**
 *  snd_card_new - create and initialize a soundcard structure
 *  @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
 *  @xid: card identification (ASCII string)
 *  @module: top level module for locking
 *  @extra_size: allocate this extra size after the main soundcard structure
 *
 *  Creates and initializes a soundcard structure.
 *
 *  Returns kmallocated snd_card structure. Creates the ALSA control interface
 *  (which is blocked until snd_card_register function is called).
 */
struct snd_card *snd_card_new(int idx, const char *xid,
			 struct module *module, int extra_size)
{
	struct snd_card *card;
	int err;

	if (extra_size < 0)
		extra_size = 0;
	card = kzalloc(sizeof(*card) + extra_size, GFP_KERNEL);
	if (card == NULL)
		return NULL;
	if (xid) {
		if (!snd_info_check_reserved_words(xid))
			goto __error;
		strlcpy(card->id, xid, sizeof(card->id));
	}
	err = 0;
	mutex_lock(&snd_card_mutex);
	if (idx < 0) {
		int idx2;
		for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++)
			/* idx == -1 == 0xffff means: take any free slot */
			if (~snd_cards_lock & idx & 1<<idx2) {
				idx = idx2;
				if (idx >= snd_ecards_limit)
					snd_ecards_limit = idx + 1;
				break;
			}
	} else {
		 if (idx < snd_ecards_limit) {
			if (snd_cards_lock & (1 << idx))
				err = -EBUSY;	/* invalid */
		} else {
			if (idx < SNDRV_CARDS)
				snd_ecards_limit = idx + 1; /* increase the limit */
			else
				err = -ENODEV;
		}
	}
	if (idx < 0 || err < 0) {
		mutex_unlock(&snd_card_mutex);
		snd_printk(KERN_ERR "cannot find the slot for index %d (range 0-%i), error: %d\n",
			 idx, snd_ecards_limit - 1, err);
		goto __error;
	}
	snd_cards_lock |= 1 << idx;		/* lock it */
	mutex_unlock(&snd_card_mutex);
	card->number = idx;
	card->module = module;
	INIT_LIST_HEAD(&card->devices);
	init_rwsem(&card->controls_rwsem);
	rwlock_init(&card->ctl_files_rwlock);
	INIT_LIST_HEAD(&card->controls);
	INIT_LIST_HEAD(&card->ctl_files);
	spin_lock_init(&card->files_lock);
	init_waitqueue_head(&card->shutdown_sleep);
#ifdef CONFIG_PM
	mutex_init(&card->power_lock);
	init_waitqueue_head(&card->power_sleep);
#endif
	/* the control interface cannot be accessed from the user space until */
	/* snd_cards_bitmask and snd_cards are set with snd_card_register */
	if ((err = snd_ctl_create(card)) < 0) {
		snd_printd("unable to register control minors\n");
		goto __error;
	}
	if ((err = snd_info_card_create(card)) < 0) {
		snd_printd("unable to create card info\n");
		goto __error_ctl;
	}
	if (extra_size > 0)
		card->private_data = (char *)card + sizeof(struct snd_card);
	return card;

      __error_ctl:
	snd_device_free_all(card, SNDRV_DEV_CMD_PRE);
      __error:
	kfree(card);
      	return NULL;
}

EXPORT_SYMBOL(snd_card_new);

/* return non-zero if a card is already locked */
int snd_card_locked(int card)
{
	int locked;

	mutex_lock(&snd_card_mutex);
	locked = snd_cards_lock & (1 << card);
	mutex_unlock(&snd_card_mutex);
	return locked;
}

static loff_t snd_disconnect_llseek(struct file *file, loff_t offset, int orig)
{
	return -ENODEV;
}

static ssize_t snd_disconnect_read(struct file *file, char __user *buf,
				   size_t count, loff_t *offset)
{
	return -ENODEV;
}

static ssize_t snd_disconnect_write(struct file *file, const char __user *buf,
				    size_t count, loff_t *offset)
{
	return -ENODEV;
}

static int snd_disconnect_release(struct inode *inode, struct file *file)
{
	struct snd_monitor_file *df = NULL, *_df;

	spin_lock(&shutdown_lock);
	list_for_each_entry(_df, &shutdown_files, shutdown_list) {
		if (_df->file == file) {
			df = _df;
			break;
		}
	}
	spin_unlock(&shutdown_lock);

	if (likely(df))
		return df->disconnected_f_op->release(inode, file);

	panic("%s(%p, %p) failed!", __FUNCTION__, inode, file);
}

static unsigned int snd_disconnect_poll(struct file * file, poll_table * wait)
{
	return POLLERR | POLLNVAL;
}

static long snd_disconnect_ioctl(struct file *file,
				 unsigned int cmd, unsigned long arg)
{
	return -ENODEV;
}

static int snd_disconnect_mmap(struct file *file, struct vm_area_struct *vma)
{
	return -ENODEV;
}

static int snd_disconnect_fasync(int fd, struct file *file, int on)
{
	return -ENODEV;
}

static const struct file_operations snd_shutdown_f_ops =
{
	.owner = 	THIS_MODULE,
	.llseek =	snd_disconnect_llseek,
	.read = 	snd_disconnect_read,
	.write =	snd_disconnect_write,
	.release =	snd_disconnect_release,
	.poll =		snd_disconnect_poll,
	.unlocked_ioctl = snd_disconnect_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = snd_disconnect_ioctl,
#endif
	.mmap =		snd_disconnect_mmap,
	.fasync =	snd_disconnect_fasync
};

/**
 *  snd_card_disconnect - disconnect all APIs from the file-operations (user space)
 *  @card: soundcard structure
 *
 *  Disconnects all APIs from the file-operations (user space).
 *
 *  Returns zero, otherwise a negative error code.
 *
 *  Note: The current implementation replaces all active file->f_op with special
 *        dummy file operations (they do nothing except release).
 */
int snd_card_disconnect(struct snd_card *card)
{
	struct snd_monitor_file *mfile;
	struct file *file;
	int err;

	spin_lock(&card->files_lock);
	if (card->shutdown) {
		spin_unlock(&card->files_lock);
		return 0;
	}
	card->shutdown = 1;
	spin_unlock(&card->files_lock);

	/* phase 1: disable fops (user space) operations for ALSA API */
	mutex_lock(&snd_card_mutex);
	snd_cards[card->number] = NULL;
	mutex_unlock(&snd_card_mutex);
	
	/* phase 2: replace file->f_op with special dummy operations */
	
	spin_lock(&card->files_lock);
	mfile = card->files;
	while (mfile) {
		file = mfile->file;

		/* it's critical part, use endless loop */
		/* we have no room to fail */
		mfile->disconnected_f_op = mfile->file->f_op;

		spin_lock(&shutdown_lock);
		list_add(&mfile->shutdown_list, &shutdown_files);
		spin_unlock(&shutdown_lock);

		fops_get(&snd_shutdown_f_ops);
		mfile->file->f_op = &snd_shutdown_f_ops;
		
		mfile = mfile->next;
	}
	spin_unlock(&card->files_lock);	

	/* phase 3: notify all connected devices about disconnection */
	/* at this point, they cannot respond to any calls except release() */

#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
	if (snd_mixer_oss_notify_callback)
		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_DISCONNECT);
#endif

	/* notify all devices that we are disconnected */
	err = snd_device_disconnect_all(card);
	if (err < 0)
		snd_printk(KERN_ERR "not all devices for card %i can be disconnected\n", card->number);

	snd_info_card_disconnect(card);
	return 0;	
}

EXPORT_SYMBOL(snd_card_disconnect);

/**
 *  snd_card_free - frees given soundcard structure
 *  @card: soundcard structure
 *
 *  This function releases the soundcard structure and the all assigned
 *  devices automatically.  That is, you don't have to release the devices
 *  by yourself.
 *
 *  Returns zero. Frees all associated devices and frees the control
 *  interface associated to given soundcard.
 */
static int snd_card_do_free(struct snd_card *card)
{
#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
	if (snd_mixer_oss_notify_callback)
		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE);
#endif
	if (snd_device_free_all(card, SNDRV_DEV_CMD_PRE) < 0) {
		snd_printk(KERN_ERR "unable to free all devices (pre)\n");
		/* Fatal, but this situation should never occur */
	}
	if (snd_device_free_all(card, SNDRV_DEV_CMD_NORMAL) < 0) {
		snd_printk(KERN_ERR "unable to free all devices (normal)\n");
		/* Fatal, but this situation should never occur */
	}
	if (snd_device_free_all(card, SNDRV_DEV_CMD_POST) < 0) {
		snd_printk(KERN_ERR "unable to free all devices (post)\n");
		/* Fatal, but this situation should never occur */
	}
	if (card->private_free)
		card->private_free(card);
	snd_info_free_entry(card->proc_id);
	if (snd_info_card_free(card) < 0) {
		snd_printk(KERN_WARNING "unable to free card info\n");
		/* Not fatal error */
	}
#ifndef CONFIG_SYSFS_DEPRECATED
	if (card->card_dev)
		device_unregister(card->card_dev);
#endif
	kfree(card);
	return 0;
}

static int snd_card_free_prepare(struct snd_card *card)
{
	if (card == NULL)
		return -EINVAL;
	(void) snd_card_disconnect(card);
	mutex_lock(&snd_card_mutex);
	snd_cards[card->number] = NULL;
	snd_cards_lock &= ~(1 << card->number);
	mutex_unlock(&snd_card_mutex);
#ifdef CONFIG_PM
	wake_up(&card->power_sleep);
#endif
	return 0;
}

int snd_card_free_when_closed(struct snd_card *card)
{
	int free_now = 0;
	int ret = snd_card_free_prepare(card);
	if (ret)
		return ret;

	spin_lock(&card->files_lock);
	if (card->files == NULL)
		free_now = 1;
	else