path: root/sound/core/pcm.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Digital Audio (PCM) abstract layer
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/time.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/nospec.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/pcm.h>
#include <sound/timer.h>
#include <sound/control.h>
#include <sound/info.h>

#include "pcm_local.h"

MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>, Abramo Bagnara <abramo@alsa-project.org>");
MODULE_DESCRIPTION("Midlevel PCM code for ALSA.");
MODULE_LICENSE("GPL");

static LIST_HEAD(snd_pcm_devices);
static DEFINE_MUTEX(register_mutex);
#if IS_ENABLED(CONFIG_SND_PCM_OSS)
static LIST_HEAD(snd_pcm_notify_list);
#endif

static int snd_pcm_free(struct snd_pcm *pcm);
static int snd_pcm_dev_free(struct snd_device *device);
static int snd_pcm_dev_register(struct snd_device *device);
static int snd_pcm_dev_disconnect(struct snd_device *device);

static struct snd_pcm *snd_pcm_get(struct snd_card *card, int device)
{
	struct snd_pcm *pcm;

	list_for_each_entry(pcm, &snd_pcm_devices, list) {
		if (pcm->card == card && pcm->device == device)
			return pcm;
	}
	return NULL;
}

static int snd_pcm_next(struct snd_card *card, int device)
{
	struct snd_pcm *pcm;

	list_for_each_entry(pcm, &snd_pcm_devices, list) {
		if (pcm->card == card && pcm->device > device)
			return pcm->device;
		else if (pcm->card->number > card->number)
			return -1;
	}
	return -1;
}

static int snd_pcm_add(struct snd_pcm *newpcm)
{
	struct snd_pcm *pcm;

	if (newpcm->internal)
		return 0;

	list_for_each_entry(pcm, &snd_pcm_devices, list) {
		if (pcm->card == newpcm->card && pcm->device == newpcm->device)
			return -EBUSY;
		if (pcm->card->number > newpcm->card->number ||
				(pcm->card == newpcm->card &&
				pcm->device > newpcm->device)) {
			list_add(&newpcm->list, pcm->list.prev);
			return 0;
		}
	}
	list_add_tail(&newpcm->list, &snd_pcm_devices);
	return 0;
}

static int snd_pcm_control_ioctl(struct snd_card *card,
				 struct snd_ctl_file *control,
				 unsigned int cmd, unsigned long arg)
{
	switch (cmd) {
	case SNDRV_CTL_IOCTL_PCM_NEXT_DEVICE:
		{
			int device;

			if (get_user(device, (int __user *)arg))
				return -EFAULT;
			scoped_guard(mutex, &register_mutex)
				device = snd_pcm_next(card, device);
			if (put_user(device, (int __user *)arg))
				return -EFAULT;
			return 0;
		}
	case SNDRV_CTL_IOCTL_PCM_INFO:
		{
			struct snd_pcm_info __user *info;
			unsigned int device, subdevice;
			int stream;
			struct snd_pcm *pcm;
			struct snd_pcm_str *pstr;
			struct snd_pcm_substream *substream;

			info = (struct snd_pcm_info __user *)arg;
			if (get_user(