Quelle  pcm_native.c   Sprache: C

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

#include <linux/compat.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/time.h>
#include <linux/pm_qos.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/vmalloc.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/info.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/timer.h>
#include <sound/minors.h>
#include <linux/uio.h>
#include <linux/delay.h>
#include <linux/bitops.h>

#include "pcm_local.h"

#ifdef CONFIG_SND_DEBUG
#define CREATE_TRACE_POINTS
#include "pcm_param_trace.h"
#else
#define trace_hw_mask_param_enabled()  0
#define trace_hw_interval_param_enabled() 0
#define trace_hw_mask_param(substream, type, index, prev, curr)
#define trace_hw_interval_param(substream, type, index, prev, curr)
#endif

/*
 *  Compatibility
 */

struct snd_pcm_hw_params_old {
 unsigned int flags;
 unsigned int masks[SNDRV_PCM_HW_PARAM_SUBFORMAT -
      SNDRV_PCM_HW_PARAM_ACCESS + 1];
 struct snd_interval intervals[SNDRV_PCM_HW_PARAM_TICK_TIME -
     SNDRV_PCM_HW_PARAM_SAMPLE_BITS + 1];
 unsigned int rmask;
 unsigned int cmask;
 unsigned int info;
 unsigned int msbits;
 unsigned int rate_num;
 unsigned int rate_den;
 snd_pcm_uframes_t fifo_size;
 unsigned char reserved[64];
};

#ifdef CONFIG_SND_SUPPORT_OLD_API
#define SNDRV_PCM_IOCTL_HW_REFINE_OLD _IOWR('A', 0x10, struct snd_pcm_hw_params_old)
#define SNDRV_PCM_IOCTL_HW_PARAMS_OLD _IOWR('A', 0x11, struct snd_pcm_hw_params_old)

static int snd_pcm_hw_refine_old_user(struct snd_pcm_substream *substream,
          struct snd_pcm_hw_params_old __user * _oparams);
static int snd_pcm_hw_params_old_user(struct snd_pcm_substream *substream,
          struct snd_pcm_hw_params_old __user * _oparams);
#endif
static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream);

/*
 *
 */

static DECLARE_RWSEM(snd_pcm_link_rwsem);

void snd_pcm_group_init(struct snd_pcm_group *group)
{
 spin_lock_init(&group->lock);
 mutex_init(&group->mutex);
 INIT_LIST_HEAD(&group->substreams);
 refcount_set(&group->refs, 1);
}

/* define group lock helpers */
#define DEFINE_PCM_GROUP_LOCK(action, bh_lock, bh_unlock, mutex_action) \
static void snd_pcm_group_ ## action(struct snd_pcm_group *group, bool nonatomic) \
{ \
 if (nonatomic) { \
  mutex_ ## mutex_action(&group->mutex); \
 } else { \
  if (IS_ENABLED(CONFIG_PREEMPT_RT) && bh_lock)   \
   local_bh_disable();   \
  spin_ ## action(&group->lock);   \
  if (IS_ENABLED(CONFIG_PREEMPT_RT) && bh_unlock) \
   local_bh_enable();                      \
 }       \
}

DEFINE_PCM_GROUP_LOCK(lock, false, false, lock);
DEFINE_PCM_GROUP_LOCK(unlock, false, false, unlock);
DEFINE_PCM_GROUP_LOCK(lock_irq, true, false, lock);
DEFINE_PCM_GROUP_LOCK(unlock_irq, false, true, unlock);

/**
 * snd_pcm_stream_lock - Lock the PCM stream
 * @substream: PCM substream
 *
 * This locks the PCM stream's spinlock or mutex depending on the nonatomic
 * flag of the given substream.  This also takes the global link rw lock
 * (or rw sem), too, for avoiding the race with linked streams.
 */
void snd_pcm_stream_lock(struct snd_pcm_substream *substream)
{
 snd_pcm_group_lock(&substream->self_group, substream->pcm->nonatomic);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_lock);

/**
 * snd_pcm_stream_unlock - Unlock the PCM stream
 * @substream: PCM substream
 *
 * This unlocks the PCM stream that has been locked via snd_pcm_stream_lock().
 */
void snd_pcm_stream_unlock(struct snd_pcm_substream *substream)
{
 snd_pcm_group_unlock(&substream->self_group, substream->pcm->nonatomic);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock);

/**
 * snd_pcm_stream_lock_irq - Lock the PCM stream
 * @substream: PCM substream
 *
 * This locks the PCM stream like snd_pcm_stream_lock() and disables the local
 * IRQ (only when nonatomic is false).  In nonatomic case, this is identical
 * as snd_pcm_stream_lock().
 */
void snd_pcm_stream_lock_irq(struct snd_pcm_substream *substream)
{
 snd_pcm_group_lock_irq(&substream->self_group,
          substream->pcm->nonatomic);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_lock_irq);

static void snd_pcm_stream_lock_nested(struct snd_pcm_substream *substream)
{
 struct snd_pcm_group *group = &substream->self_group;

 if (substream->pcm->nonatomic)
  mutex_lock_nested(&group->mutex, SINGLE_DEPTH_NESTING);
 else
  spin_lock_nested(&group->lock, SINGLE_DEPTH_NESTING);
}

/**
 * snd_pcm_stream_unlock_irq - Unlock the PCM stream
 * @substream: PCM substream
 *
 * This is a counter-part of snd_pcm_stream_lock_irq().
 */
void snd_pcm_stream_unlock_irq(struct snd_pcm_substream *substream)
{
 snd_pcm_group_unlock_irq(&substream->self_group,
     substream->pcm->nonatomic);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irq);

unsigned long _snd_pcm_stream_lock_irqsave(struct snd_pcm_substream *substream)
{
 unsigned long flags = 0;
 if (substream->pcm->nonatomic)
  mutex_lock(&substream->self_group.mutex);
 else
  spin_lock_irqsave(&substream->self_group.lock, flags);
 return flags;
}
EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave);

unsigned long _snd_pcm_stream_lock_irqsave_nested(struct snd_pcm_substream *substream)
{
 unsigned long flags = 0;
 if (substream->pcm->nonatomic)
  mutex_lock_nested(&substream->self_group.mutex,
      SINGLE_DEPTH_NESTING);
 else
  spin_lock_irqsave_nested(&substream->self_group.lock, flags,
      SINGLE_DEPTH_NESTING);
 return flags;
}
EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave_nested);

/**
 * snd_pcm_stream_unlock_irqrestore - Unlock the PCM stream
 * @substream: PCM substream
 * @flags: irq flags
 *
 * This is a counter-part of snd_pcm_stream_lock_irqsave().
 */
void snd_pcm_stream_unlock_irqrestore(struct snd_pcm_substream *substream,
          unsigned long flags)
{
 if (substream->pcm->nonatomic)
  mutex_unlock(&substream->self_group.mutex);
 else
  spin_unlock_irqrestore(&substream->self_group.lock, flags);
}
EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock_irqrestore);

/* Run PCM ioctl ops */
static int snd_pcm_ops_ioctl(struct snd_pcm_substream *substream,
        unsigned cmd, void *arg)
{
 if (substream->ops->ioctl)
  return substream->ops->ioctl(substream, cmd, arg);
 else
  return snd_pcm_lib_ioctl(substream, cmd, arg);
}

int snd_pcm_info(struct snd_pcm_substream *substream, struct snd_pcm_info *info)
{
 struct snd_pcm *pcm = substream->pcm;
 struct snd_pcm_str *pstr = substream->pstr;

 memset(info, 0, sizeof(*info));
 info->card = pcm->card->number;
 info->device = pcm->device;
 info->stream = substream->stream;
 info->subdevice = substream->number;
 strscpy(info->id, pcm->id, sizeof(info->id));
 strscpy(info->name, pcm->name, sizeof(info->name));
 info->dev_class = pcm->dev_class;
 info->dev_subclass = pcm->dev_subclass;
 info->subdevices_count = pstr->substream_count;
 info->subdevices_avail = pstr->substream_count - pstr->substream_opened;
 strscpy(info->subname, substream->name, sizeof(info->subname));

 return 0;
}

int snd_pcm_info_user(struct snd_pcm_substream *substream,
        struct snd_pcm_info __user * _info)
{
 struct snd_pcm_info *info __free(kfree) = NULL;
 int err;

 info = kmalloc(sizeof(*info), GFP_KERNEL);
 if (! info)
  return -ENOMEM;
 err = snd_pcm_info(substream, info);
 if (err >= 0) {
  if (copy_to_user(_info, info, sizeof(*info)))
   err = -EFAULT;
 }
 return err;
}

/* macro for simplified cast */
#define PARAM_MASK_BIT(b) (1U << (__force int)(b))

static bool hw_support_mmap(struct snd_pcm_substream *substream)
{
 struct snd_dma_buffer *dmabuf;

 if (!(substream->runtime->hw.info & SNDRV_PCM_INFO_MMAP))
  return false;

 if (substream->ops->mmap || substream->ops->page)
  return true;

 dmabuf = snd_pcm_get_dma_buf(substream);
 if (!dmabuf)
  dmabuf = &substream->dma_buffer;
 switch (dmabuf->dev.type) {
 case SNDRV_DMA_TYPE_UNKNOWN:
  /* we can't know the device, so just assume that the driver does
 * everything right
 */
  return true;
 case SNDRV_DMA_TYPE_CONTINUOUS:
 case SNDRV_DMA_TYPE_VMALLOC:
  return true;
 default:
  return dma_can_mmap(dmabuf->dev.dev);
 }
}

static int constrain_mask_params(struct snd_pcm_substream *substream,
     struct snd_pcm_hw_params *params)
{
 struct snd_pcm_hw_constraints *constrs =
     &substream->runtime->hw_constraints;
 struct snd_mask *m;
 unsigned int k;
 struct snd_mask old_mask __maybe_unused;
 int changed;

 for (k = SNDRV_PCM_HW_PARAM_FIRST_MASK; k <= SNDRV_PCM_HW_PARAM_LAST_MASK; k++) {
  m = hw_param_mask(params, k);
  if (snd_mask_empty(m))
   return -EINVAL;

  /* This parameter is not requested to change by a caller. */
  if (!(params->rmask & PARAM_MASK_BIT(k)))
   continue;

  if (trace_hw_mask_param_enabled())
   old_mask = *m;

  changed = snd_mask_refine(m, constrs_mask(constrs, k));
  if (changed < 0)
   return changed;
  if (changed == 0)
   continue;

  /* Set corresponding flag so that the caller gets it. */
  trace_hw_mask_param(substream, k, 0, &old_mask, m);
  params->cmask |= PARAM_MASK_BIT(k);
 }

 return 0;
}

static int constrain_interval_params(struct snd_pcm_substream *substream,
         struct snd_pcm_hw_params *params)
{
 struct snd_pcm_hw_constraints *constrs =
     &substream->runtime->hw_constraints;
 struct snd_interval *i;
 unsigned int k;
 struct snd_interval old_interval __maybe_unused;
 int changed;

 for (k = SNDRV_PCM_HW_PARAM_FIRST_INTERVAL; k <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; k++) {
  i = hw_param_interval(params, k);
  if (snd_interval_empty(i))
   return -EINVAL;

  /* This parameter is not requested to change by a caller. */
  if (!(params->rmask & PARAM_MASK_BIT(k)))
   continue;

  if (trace_hw_interval_param_enabled())
   old_interval = *i;

  changed = snd_interval_refine(i, constrs_interval(constrs, k));
  if (changed < 0)
   return changed;
  if (changed == 0)
   continue;

  /* Set corresponding flag so that the caller gets it. */
  trace_hw_interval_param(substream, k, 0, &old_interval, i);
  params->cmask |= PARAM_MASK_BIT(k);
 }

 return 0;
}

static int constrain_params_by_rules(struct snd_pcm_substream *substream,
         struct snd_pcm_hw_params *params)
{
 struct snd_pcm_hw_constraints *constrs =
     &substream->runtime->hw_constraints;
 unsigned int k;
 unsigned int *rstamps __free(kfree) = NULL;
 unsigned int vstamps[SNDRV_PCM_HW_PARAM_LAST_INTERVAL + 1];
 unsigned int stamp;
 struct snd_pcm_hw_rule *r;
 unsigned int d;
 struct snd_mask old_mask __maybe_unused;
 struct snd_interval old_interval __maybe_unused;
 bool again;
 int changed, err = 0;

 /*
 * Each application of rule has own sequence number.
 *
 * Each member of 'rstamps' array represents the sequence number of
 * recent application of corresponding rule.
 */
 rstamps = kcalloc(constrs->rules_num, sizeof(unsigned int), GFP_KERNEL);
 if (!rstamps)
  return -ENOMEM;

 /*
 * Each member of 'vstamps' array represents the sequence number of
 * recent application of rule in which corresponding parameters were
 * changed.
 *
 * In initial state, elements corresponding to parameters requested by
 * a caller is 1. For unrequested parameters, corresponding members
 * have 0 so that the parameters are never changed anymore.
 */
 for (k = 0; k <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; k++)
  vstamps[k] = (params->rmask & PARAM_MASK_BIT(k)) ? 1 : 0;

 /* Due to the above design, actual sequence number starts at 2. */
 stamp = 2;
retry:
 /* Apply all rules in order. */
 again = false;
 for (k = 0; k < constrs->rules_num; k++) {
  r = &constrs->rules[k];

  /*
 * Check condition bits of this rule. When the rule has
 * some condition bits, parameter without the bits is
 * never processed. SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP
 * is an example of the condition bits.
 */
  if (r->cond && !(r->cond & params->flags))
   continue;

  /*
 * The 'deps' array includes maximum four dependencies
 * to SNDRV_PCM_HW_PARAM_XXXs for this rule. The fifth
 * member of this array is a sentinel and should be
 * negative value.
 *
 * This rule should be processed in this time when dependent
 * parameters were changed at former applications of the other
 * rules.
 */
  for (d = 0; r->deps[d] >= 0; d++) {
   if (vstamps[r->deps[d]] > rstamps[k])
    break;
  }
  if (r->deps[d] < 0)
   continue;

  if (trace_hw_mask_param_enabled()) {
   if (hw_is_mask(r->var))
    old_mask = *hw_param_mask(params, r->var);
  }
  if (trace_hw_interval_param_enabled()) {
   if (hw_is_interval(r->var))
    old_interval = *hw_param_interval(params, r->var);
  }

  changed = r->func(params, r);
  if (changed < 0)
   return changed;

  /*
 * When the parameter is changed, notify it to the caller
 * by corresponding returned bit, then preparing for next
 * iteration.
 */
  if (changed && r->var >= 0) {
   if (hw_is_mask(r->var)) {
    trace_hw_mask_param(substream, r->var,
     k + 1, &old_mask,
     hw_param_mask(params, r->var));
   }
   if (hw_is_interval(r->var)) {
    trace_hw_interval_param(substream, r->var,
     k + 1, &old_interval,
     hw_param_interval(params, r->var));
   }

   params->cmask |= PARAM_MASK_BIT(r->var);
   vstamps[r->var] = stamp;
   again = true;
  }

  rstamps[k] = stamp++;
 }

 /* Iterate to evaluate all rules till no parameters are changed. */
 if (again)
  goto retry;

 return err;
}

static int fixup_unreferenced_params(struct snd_pcm_substream *substream,
         struct snd_pcm_hw_params *params)
{
 const struct snd_interval *i;
 const struct snd_mask *m;
 struct snd_mask *m_rw;
 int err;

 if (!params->msbits) {
  i = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_SAMPLE_BITS);
  if (snd_interval_single(i))
   params->msbits = snd_interval_value(i);
  m = hw_param_mask_c(params, SNDRV_PCM_HW_PARAM_FORMAT);
  if (snd_mask_single(m)) {
   snd_pcm_format_t format = (__force snd_pcm_format_t)snd_mask_min(m);
   params->msbits = snd_pcm_format_width(format);
  }
 }

 if (params->msbits) {
  m = hw_param_mask_c(params, SNDRV_PCM_HW_PARAM_FORMAT);
  if (snd_mask_single(m)) {
   snd_pcm_format_t format = (__force snd_pcm_format_t)snd_mask_min(m);

   if (snd_pcm_format_linear(format) &&
       snd_pcm_format_width(format) != params->msbits) {
    m_rw = hw_param_mask(params, SNDRV_PCM_HW_PARAM_SUBFORMAT);
    snd_mask_reset(m_rw,
            (__force unsigned)SNDRV_PCM_SUBFORMAT_MSBITS_MAX);
    if (snd_mask_empty(m_rw))
     return -EINVAL;
   }
  }
 }

 if (!params->rate_den) {
  i = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
  if (snd_interval_single(i)) {
   params->rate_num = snd_interval_value(i);
   params->rate_den = 1;
  }
 }

 if (!params->fifo_size) {
  m = hw_param_mask_c(params, SNDRV_PCM_HW_PARAM_FORMAT);
  i = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_CHANNELS);
  if (snd_mask_single(m) && snd_interval_single(i)) {
   err = snd_pcm_ops_ioctl(substream,
      SNDRV_PCM_IOCTL1_FIFO_SIZE,
      params);
   if (err < 0)
    return err;
  }
 }

 if (!params->info) {
  params->info = substream->runtime->hw.info;
  params->info &= ~(SNDRV_PCM_INFO_FIFO_IN_FRAMES |
      SNDRV_PCM_INFO_DRAIN_TRIGGER);
  if (!hw_support_mmap(substream))
   params->info &= ~(SNDRV_PCM_INFO_MMAP |
       SNDRV_PCM_INFO_MMAP_VALID);
 }

 err = snd_pcm_ops_ioctl(substream,
    SNDRV_PCM_IOCTL1_SYNC_ID,
    params);
 if (err < 0)
  return err;

 return 0;
}

int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
        struct snd_pcm_hw_params *params)
{
 int err;

 params->info = 0;
 params->fifo_size = 0;
 if (params->rmask & PARAM_MASK_BIT(SNDRV_PCM_HW_PARAM_SAMPLE_BITS))
  params->msbits = 0;
 if (params->rmask & PARAM_MASK_BIT(SNDRV_PCM_HW_PARAM_RATE)) {
  params->rate_num = 0;
  params->rate_den = 0;
 }

 err = constrain_mask_params(substream, params);
 if (err < 0)
  return err;

 err = constrain_interval_params(substream, params);
 if (err < 0)
  return err;

 err = constrain_params_by_rules(substream, params);
 if (err < 0)
  return err;

 params->rmask = 0;

 return 0;
}
EXPORT_SYMBOL(snd_pcm_hw_refine);

static int snd_pcm_hw_refine_user(struct snd_pcm_substream *substream,
      struct snd_pcm_hw_params __user * _params)
{
 struct snd_pcm_hw_params *params __free(kfree) = NULL;
 int err;

 params = memdup_user(_params, sizeof(*params));
 if (IS_ERR(params))
  return PTR_ERR(params);

 err = snd_pcm_hw_refine(substream, params);
 if (err < 0)
  return err;

 err = fixup_unreferenced_params(substream, params);
 if (err < 0)
  return err;

 if (copy_to_user(_params, params, sizeof(*params)))
  return -EFAULT;
 return 0;
}

static int period_to_usecs(struct snd_pcm_runtime *runtime)
{
 int usecs;

 if (! runtime->rate)
  return -1; /* invalid */

 /* take 75% of period time as the deadline */
 usecs = (750000 / runtime->rate) * runtime->period_size;
 usecs += ((750000 % runtime->rate) * runtime->period_size) /
  runtime->rate;

 return usecs;
}

static void snd_pcm_set_state(struct snd_pcm_substream *substream,
         snd_pcm_state_t state)
{
 guard(pcm_stream_lock_irq)(substream);
 if (substream->runtime->state != SNDRV_PCM_STATE_DISCONNECTED)
  __snd_pcm_set_state(substream->runtime, state);
}

static inline void snd_pcm_timer_notify(struct snd_pcm_substream *substream,
     int event)
{
#ifdef CONFIG_SND_PCM_TIMER
 if (substream->timer)
  snd_timer_notify(substream->timer, event,
     &substream->runtime->trigger_tstamp);
#endif
}

void snd_pcm_sync_stop(struct snd_pcm_substream *substream, bool sync_irq)
{
 if (substream->runtime && substream->runtime->stop_operating) {
  substream->runtime->stop_operating = false;
  if (substream->ops && substream->ops->sync_stop)
   substream->ops->sync_stop(substream);
  else if (sync_irq && substream->pcm->card->sync_irq > 0)
   synchronize_irq(substream->pcm->card->sync_irq);
 }
}

/**
 * snd_pcm_hw_params_choose - choose a configuration defined by @params
 * @pcm: PCM instance
 * @params: the hw_params instance
 *
 * Choose one configuration from configuration space defined by @params.
 * The configuration chosen is that obtained fixing in this order:
 * first access, first format, first subformat, min channels,
 * min rate, min period time, max buffer size, min tick time
 *
 * Return: Zero if successful, or a negative error code on failure.
 */
static int snd_pcm_hw_params_choose(struct snd_pcm_substream *pcm,
        struct snd_pcm_hw_params *params)
{
 static const int vars[] = {
  SNDRV_PCM_HW_PARAM_ACCESS,
  SNDRV_PCM_HW_PARAM_FORMAT,
  SNDRV_PCM_HW_PARAM_SUBFORMAT,
  SNDRV_PCM_HW_PARAM_CHANNELS,
  SNDRV_PCM_HW_PARAM_RATE,
  SNDRV_PCM_HW_PARAM_PERIOD_TIME,
  SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
  SNDRV_PCM_HW_PARAM_TICK_TIME,
  -1
 };
 const int *v;
 struct snd_mask old_mask __maybe_unused;
 struct snd_interval old_interval __maybe_unused;
 int changed;

 for (v = vars; *v != -1; v++) {
  /* Keep old parameter to trace. */
  if (trace_hw_mask_param_enabled()) {
   if (hw_is_mask(*v))
    old_mask = *hw_param_mask(params, *v);
  }
  if (trace_hw_interval_param_enabled()) {
   if (hw_is_interval(*v))
    old_interval = *hw_param_interval(params, *v);
  }
  if (*v != SNDRV_PCM_HW_PARAM_BUFFER_SIZE)
   changed = snd_pcm_hw_param_first(pcm, params, *v, NULL);
  else
   changed = snd_pcm_hw_param_last(pcm, params, *v, NULL);
  if (changed < 0)
   return changed;
  if (changed == 0)
   continue;

  /* Trace the changed parameter. */
  if (hw_is_mask(*v)) {
   trace_hw_mask_param(pcm, *v, 0, &old_mask,
         hw_param_mask(params, *v));
  }
  if (hw_is_interval(*v)) {
   trace_hw_interval_param(pcm, *v, 0, &old_interval,
      hw_param_interval(params, *v));
  }
 }

 return 0;
}

/* acquire buffer_mutex; if it's in r/w operation, return -EBUSY, otherwise
 * block the further r/w operations
 */
static int snd_pcm_buffer_access_lock(struct snd_pcm_runtime *runtime)
{
 if (!atomic_dec_unless_positive(&runtime->buffer_accessing))
  return -EBUSY;
 mutex_lock(&runtime->buffer_mutex);
 return 0; /* keep buffer_mutex, unlocked by below */
}

/* release buffer_mutex and clear r/w access flag */
static void snd_pcm_buffer_access_unlock(struct snd_pcm_runtime *runtime)
{
 mutex_unlock(&runtime->buffer_mutex);
 atomic_inc(&runtime->buffer_accessing);
}

/* fill the PCM buffer with the current silence format; called from pcm_oss.c */
void snd_pcm_runtime_buffer_set_silence(struct snd_pcm_runtime *runtime)
{
 snd_pcm_buffer_access_lock(runtime);
 if (runtime->dma_area)
  snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
        bytes_to_samples(runtime, runtime->dma_bytes));
 snd_pcm_buffer_access_unlock(runtime);
}
EXPORT_SYMBOL_GPL(snd_pcm_runtime_buffer_set_silence);

#if IS_ENABLED(CONFIG_SND_PCM_OSS)
#define is_oss_stream(substream) ((substream)->oss.oss)
#else
#define is_oss_stream(substream) false
#endif

static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
        struct snd_pcm_hw_params *params)
{
 struct snd_pcm_runtime *runtime;
 int err, usecs;
 unsigned int bits;
 snd_pcm_uframes_t frames;

 if (PCM_RUNTIME_CHECK(substream))
  return -ENXIO;
 runtime = substream->runtime;
 err = snd_pcm_buffer_access_lock(runtime);
 if (err < 0)
  return err;
 scoped_guard(pcm_stream_lock_irq, substream) {
  switch (runtime->state) {
  case SNDRV_PCM_STATE_OPEN:
  case SNDRV_PCM_STATE_SETUP:
  case SNDRV_PCM_STATE_PREPARED:
   if (!is_oss_stream(substream) &&
       atomic_read(&substream->mmap_count))
    err = -EBADFD;
   break;
  default:
   err = -EBADFD;
   break;
  }
 }
 if (err)
  goto unlock;

 snd_pcm_sync_stop(substream, true);

 params->rmask = ~0U;
 err = snd_pcm_hw_refine(substream, params);
 if (err < 0)
  goto _error;

 err = snd_pcm_hw_params_choose(substream, params);
 if (err < 0)
  goto _error;

 err = fixup_unreferenced_params(substream, params);
 if (err < 0)
  goto _error;

 if (substream->managed_buffer_alloc) {
  err = snd_pcm_lib_malloc_pages(substream,
            params_buffer_bytes(params));
  if (err < 0)
   goto _error;
  runtime->buffer_changed = err > 0;
 }

 if (substream->ops->hw_params != NULL) {
  err = substream->ops->hw_params(substream, params);
  if (err < 0)
   goto _error;
 }

 runtime->access = params_access(params);
 runtime->format = params_format(params);
 runtime->subformat = params_subformat(params);
 runtime->channels = params_channels(params);
 runtime->rate = params_rate(params);
 runtime->period_size = params_period_size(params);
 runtime->periods = params_periods(params);
 runtime->buffer_size = params_buffer_size(params);
 runtime->info = params->info;
 runtime->rate_num = params->rate_num;
 runtime->rate_den = params->rate_den;
 runtime->no_period_wakeup =
   (params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP) &&
   (params->flags & SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP);

 bits = snd_pcm_format_physical_width(runtime->format);
 runtime->sample_bits = bits;
 bits *= runtime->channels;
 runtime->frame_bits = bits;
 frames = 1;
 while (bits % 8 != 0) {
  bits *= 2;
  frames *= 2;
 }
 runtime->byte_align = bits / 8;
 runtime->min_align = frames;

 /* Default sw params */
 runtime->tstamp_mode = SNDRV_PCM_TSTAMP_NONE;
 runtime->period_step = 1;
 runtime->control->avail_min = runtime->period_size;
 runtime->start_threshold = 1;
 runtime->stop_threshold = runtime->buffer_size;
 runtime->silence_threshold = 0;
 runtime->silence_size = 0;
 runtime->boundary = runtime->buffer_size;
 while (runtime->boundary * 2 <= LONG_MAX - runtime->buffer_size)
  runtime->boundary *= 2;

 /* clear the buffer for avoiding possible kernel info leaks */
 if (runtime->dma_area && !substream->ops->copy) {
  size_t size = runtime->dma_bytes;

  if (runtime->info & SNDRV_PCM_INFO_MMAP)
   size = PAGE_ALIGN(size);
  memset(runtime->dma_area, 0, size);
 }

 snd_pcm_timer_resolution_change(substream);
 snd_pcm_set_state(substream, SNDRV_PCM_STATE_SETUP);

 if (cpu_latency_qos_request_active(&substream->latency_pm_qos_req))
  cpu_latency_qos_remove_request(&substream->latency_pm_qos_req);
 usecs = period_to_usecs(runtime);
 if (usecs >= 0)
  cpu_latency_qos_add_request(&substream->latency_pm_qos_req,
         usecs);
 err = 0;
 _error:
 if (err) {
  /* hardware might be unusable from this time,
 * so we force application to retry to set
 * the correct hardware parameter settings
 */
  snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
  if (substream->ops->hw_free != NULL)
   substream->ops->hw_free(substream);
  if (substream->managed_buffer_alloc)
   snd_pcm_lib_free_pages(substream);
 }
 unlock:
 snd_pcm_buffer_access_unlock(runtime);
 return err;
}

static int snd_pcm_hw_params_user(struct snd_pcm_substream *substream,
      struct snd_pcm_hw_params __user * _params)
{
 struct snd_pcm_hw_params *params __free(kfree) = NULL;
 int err;

 params = memdup_user(_params, sizeof(*params));
 if (IS_ERR(params))
  return PTR_ERR(params);

 err = snd_pcm_hw_params(substream, params);
 if (err < 0)
  return err;

 if (copy_to_user(_params, params, sizeof(*params)))
  return -EFAULT;
 return err;
}

static int do_hw_free(struct snd_pcm_substream *substream)
{
 int result = 0;

 snd_pcm_sync_stop(substream, true);
 if (substream->ops->hw_free)
  result = substream->ops->hw_free(substream);
 if (substream->managed_buffer_alloc)
  snd_pcm_lib_free_pages(substream);
 return result;
}

static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
{
 struct snd_pcm_runtime *runtime;
 int result = 0;

 if (PCM_RUNTIME_CHECK(substream))
  return -ENXIO;
 runtime = substream->runtime;
 result = snd_pcm_buffer_access_lock(runtime);
 if (result < 0)
  return result;
 scoped_guard(pcm_stream_lock_irq, substream) {
  switch (runtime->state) {
  case SNDRV_PCM_STATE_SETUP:
  case SNDRV_PCM_STATE_PREPARED:
   if (atomic_read(&substream->mmap_count))
    result = -EBADFD;
   break;
  default:
   result = -EBADFD;
   break;
  }
 }
 if (result)
  goto unlock;
 result = do_hw_free(substream);
 snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
 cpu_latency_qos_remove_request(&substream->latency_pm_qos_req);
 unlock:
 snd_pcm_buffer_access_unlock(runtime);
 return result;
}

static int snd_pcm_sw_params(struct snd_pcm_substream *substream,
        struct snd_pcm_sw_params *params)
{
 struct snd_pcm_runtime *runtime;
 int err;

 if (PCM_RUNTIME_CHECK(substream))
  return -ENXIO;
 runtime = substream->runtime;
 scoped_guard(pcm_stream_lock_irq, substream) {
  if (runtime->state == SNDRV_PCM_STATE_OPEN)
   return -EBADFD;
 }

 if (params->tstamp_mode < 0 ||
     params->tstamp_mode > SNDRV_PCM_TSTAMP_LAST)
  return -EINVAL;
 if (params->proto >= SNDRV_PROTOCOL_VERSION(2, 0, 12) &&
     params->tstamp_type > SNDRV_PCM_TSTAMP_TYPE_LAST)
  return -EINVAL;
 if (params->avail_min == 0)
  return -EINVAL;
 if (params->silence_size >= runtime->boundary) {
  if (params->silence_threshold != 0)
   return -EINVAL;
 } else {
  if (params->silence_size > params->silence_threshold)
   return -EINVAL;
  if (params->silence_threshold > runtime->buffer_size)
   return -EINVAL;
 }
 err = 0;
 scoped_guard(pcm_stream_lock_irq, substream) {
  runtime->tstamp_mode = params->tstamp_mode;
  if (params->proto >= SNDRV_PROTOCOL_VERSION(2, 0, 12))
   runtime->tstamp_type = params->tstamp_type;
  runtime->period_step = params->period_step;
  runtime->control->avail_min = params->avail_min;
  runtime->start_threshold = params->start_threshold;
  runtime->stop_threshold = params->stop_threshold;
  runtime->silence_threshold = params->silence_threshold;
  runtime->silence_size = params->silence_size;
  params->boundary = runtime->boundary;
  if (snd_pcm_running(substream)) {
   if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
       runtime->silence_size > 0)
    snd_pcm_playback_silence(substream, ULONG_MAX);
   err = snd_pcm_update_state(substream, runtime);
  }
 }
 return err;
}

static int snd_pcm_sw_params_user(struct snd_pcm_substream *substream,
      struct snd_pcm_sw_params __user * _params)
{
 struct snd_pcm_sw_params params;
 int err;
 if (copy_from_user(¶ms, _params, sizeof(params)))
  return -EFAULT;
 err = snd_pcm_sw_params(substream, ¶ms);
 if (copy_to_user(_params, ¶ms, sizeof(params)))
  return -EFAULT;
 return err;
}

static inline snd_pcm_uframes_t
snd_pcm_calc_delay(struct snd_pcm_substream *substream)
{
 snd_pcm_uframes_t delay;

 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
  delay = snd_pcm_playback_hw_avail(substream->runtime);
 else
  delay = snd_pcm_capture_avail(substream->runtime);
 return delay + substream->runtime->delay;
}

int snd_pcm_status64(struct snd_pcm_substream *substream,
       struct snd_pcm_status64 *status)
{
 struct snd_pcm_runtime *runtime = substream->runtime;

 guard(pcm_stream_lock_irq)(substream);

 snd_pcm_unpack_audio_tstamp_config(status->audio_tstamp_data,
     &runtime->audio_tstamp_config);

 /* backwards compatible behavior */
 if (runtime->audio_tstamp_config.type_requested ==
  SNDRV_PCM_AUDIO_TSTAMP_TYPE_COMPAT) {
  if (runtime->hw.info & SNDRV_PCM_INFO_HAS_WALL_CLOCK)
   runtime->audio_tstamp_config.type_requested =
    SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK;
  else
   runtime->audio_tstamp_config.type_requested =
    SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT;
  runtime->audio_tstamp_report.valid = 0;
 } else
  runtime->audio_tstamp_report.valid = 1;

 status->state = runtime->state;
 status->suspended_state = runtime->suspended_state;
 if (status->state == SNDRV_PCM_STATE_OPEN)
  return 0;
 status->trigger_tstamp_sec = runtime->trigger_tstamp.tv_sec;
 status->trigger_tstamp_nsec = runtime->trigger_tstamp.tv_nsec;
 if (snd_pcm_running(substream)) {
  snd_pcm_update_hw_ptr(substream);
  if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) {
   status->tstamp_sec = runtime->status->tstamp.tv_sec;
   status->tstamp_nsec =
    runtime->status->tstamp.tv_nsec;
   status->driver_tstamp_sec =
    runtime->driver_tstamp.tv_sec;
   status->driver_tstamp_nsec =
    runtime->driver_tstamp.tv_nsec;
   status->audio_tstamp_sec =
    runtime->status->audio_tstamp.tv_sec;
   status->audio_tstamp_nsec =
    runtime->status->audio_tstamp.tv_nsec;
   if (runtime->audio_tstamp_report.valid == 1)
    /* backwards compatibility, no report provided in COMPAT mode */
    snd_pcm_pack_audio_tstamp_report(&status->audio_tstamp_data,
        &status->audio_tstamp_accuracy,
        &runtime->audio_tstamp_report);

   goto _tstamp_end;
  }
 } else {
  /* get tstamp only in fallback mode and only if enabled */
  if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) {
   struct timespec64 tstamp;

   snd_pcm_gettime(runtime, &tstamp);
   status->tstamp_sec = tstamp.tv_sec;
   status->tstamp_nsec = tstamp.tv_nsec;
  }
 }
 _tstamp_end:
 status->appl_ptr = runtime->control->appl_ptr;
 status->hw_ptr = runtime->status->hw_ptr;
 status->avail = snd_pcm_avail(substream);
 status->delay = snd_pcm_running(substream) ?
  snd_pcm_calc_delay(substream) : 0;
 status->avail_max = runtime->avail_max;
 status->overrange = runtime->overrange;
 runtime->avail_max = 0;
 runtime->overrange = 0;
 return 0;
}

static int snd_pcm_status_user64(struct snd_pcm_substream *substream,
     struct snd_pcm_status64 __user * _status,
     bool ext)
{
 struct snd_pcm_status64 status;
 int res;

 memset(&status, 0, sizeof(status));
 /*
 * with extension, parameters are read/write,
 * get audio_tstamp_data from user,
 * ignore rest of status structure
 */
 if (ext && get_user(status.audio_tstamp_data,
    (u32 __user *)(&_status->audio_tstamp_data)))
  return -EFAULT;
 res = snd_pcm_status64(substream, &status);
 if (res < 0)
  return res;
 if (copy_to_user(_status, &status, sizeof(status)))
  return -EFAULT;
 return 0;
}

static int snd_pcm_status_user32(struct snd_pcm_substream *substream,
     struct snd_pcm_status32 __user * _status,
     bool ext)
{
 struct snd_pcm_status64 status64;
 struct snd_pcm_status32 status32;
 int res;

 memset(&status64, 0, sizeof(status64));
 memset(&status32, 0, sizeof(status32));
 /*
 * with extension, parameters are read/write,
 * get audio_tstamp_data from user,
 * ignore rest of status structure
 */
 if (ext && get_user(status64.audio_tstamp_data,
       (u32 __user *)(&_status->audio_tstamp_data)))
  return -EFAULT;
 res = snd_pcm_status64(substream, &status64);
 if (res < 0)
  return res;

 status32 = (struct snd_pcm_status32) {
  .state = status64.state,
  .trigger_tstamp_sec = status64.trigger_tstamp_sec,
  .trigger_tstamp_nsec = status64.trigger_tstamp_nsec,
  .tstamp_sec = status64.tstamp_sec,
  .tstamp_nsec = status64.tstamp_nsec,
  .appl_ptr = status64.appl_ptr,
  .hw_ptr = status64.hw_ptr,
  .delay = status64.delay,
  .avail = status64.avail,
  .avail_max = status64.avail_max,
  .overrange = status64.overrange,
  .suspended_state = status64.suspended_state,
  .audio_tstamp_data = status64.audio_tstamp_data,
  .audio_tstamp_sec = status64.audio_tstamp_sec,
  .audio_tstamp_nsec = status64.audio_tstamp_nsec,
  .driver_tstamp_sec = status64.audio_tstamp_sec,
  .driver_tstamp_nsec = status64.audio_tstamp_nsec,
  .audio_tstamp_accuracy = status64.audio_tstamp_accuracy,
 };

 if (copy_to_user(_status, &status32, sizeof(status32)))
  return -EFAULT;

 return 0;
}

static int snd_pcm_channel_info(struct snd_pcm_substream *substream,
    struct snd_pcm_channel_info * info)
{
 struct snd_pcm_runtime *runtime;
 unsigned int channel;
 
 channel = info->channel;
 runtime = substream->runtime;
 scoped_guard(pcm_stream_lock_irq, substream) {
  if (runtime->state == SNDRV_PCM_STATE_OPEN)
   return -EBADFD;
 }
 if (channel >= runtime->channels)
  return -EINVAL;
 memset(info, 0, sizeof(*info));
 info->channel = channel;
 return snd_pcm_ops_ioctl(substream, SNDRV_PCM_IOCTL1_CHANNEL_INFO, info);
}

static int snd_pcm_channel_info_user(struct snd_pcm_substream *substream,
         struct snd_pcm_channel_info __user * _info)
{
 struct snd_pcm_channel_info info;
 int res;
 
 if (copy_from_user(&info, _info, sizeof(info)))
  return -EFAULT;
 res = snd_pcm_channel_info(substream, &info);
 if (res < 0)
  return res;
 if (copy_to_user(_info, &info, sizeof(info)))
  return -EFAULT;
 return 0;
}

static void snd_pcm_trigger_tstamp(struct snd_pcm_substream *substream)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (runtime->trigger_master == NULL)
  return;
 if (runtime->trigger_master == substream) {
  if (!runtime->trigger_tstamp_latched)
   snd_pcm_gettime(runtime, &runtime->trigger_tstamp);
 } else {
  snd_pcm_trigger_tstamp(runtime->trigger_master);
  runtime->trigger_tstamp = runtime->trigger_master->runtime->trigger_tstamp;
 }
 runtime->trigger_master = NULL;
}

#define ACTION_ARG_IGNORE (__force snd_pcm_state_t)0

struct action_ops {
 int (*pre_action)(struct snd_pcm_substream *substream,
     snd_pcm_state_t state);
 int (*do_action)(struct snd_pcm_substream *substream,
    snd_pcm_state_t state);
 void (*undo_action)(struct snd_pcm_substream *substream,
       snd_pcm_state_t state);
 void (*post_action)(struct snd_pcm_substream *substream,
       snd_pcm_state_t state);
};

/*
 *  this functions is core for handling of linked stream
 *  Note: the stream state might be changed also on failure
 *  Note2: call with calling stream lock + link lock
 */
static int snd_pcm_action_group(const struct action_ops *ops,
    struct snd_pcm_substream *substream,
    snd_pcm_state_t state,
    bool stream_lock)
{
 struct snd_pcm_substream *s = NULL;
 struct snd_pcm_substream *s1;
 int res = 0, depth = 1;

 snd_pcm_group_for_each_entry(s, substream) {
  if (s != substream) {
   if (!stream_lock)
    mutex_lock_nested(&s->runtime->buffer_mutex, depth);
   else if (s->pcm->nonatomic)
    mutex_lock_nested(&s->self_group.mutex, depth);
   else
    spin_lock_nested(&s->self_group.lock, depth);
   depth++;
  }
  res = ops->pre_action(s, state);
  if (res < 0)
   goto _unlock;
 }
 snd_pcm_group_for_each_entry(s, substream) {
  res = ops->do_action(s, state);
  if (res < 0) {
   if (ops->undo_action) {
    snd_pcm_group_for_each_entry(s1, substream) {
     if (s1 == s) /* failed stream */
      break;
     ops->undo_action(s1, state);
    }
   }
   s = NULL; /* unlock all */
   goto _unlock;
  }
 }
 snd_pcm_group_for_each_entry(s, substream) {
  ops->post_action(s, state);
 }
 _unlock:
 /* unlock streams */
 snd_pcm_group_for_each_entry(s1, substream) {
  if (s1 != substream) {
   if (!stream_lock)
    mutex_unlock(&s1->runtime->buffer_mutex);
   else if (s1->pcm->nonatomic)
    mutex_unlock(&s1->self_group.mutex);
   else
    spin_unlock(&s1->self_group.lock);
  }
  if (s1 == s) /* end */
   break;
 }
 return res;
}

/*
 *  Note: call with stream lock
 */
static int snd_pcm_action_single(const struct action_ops *ops,
     struct snd_pcm_substream *substream,
     snd_pcm_state_t state)
{
 int res;
 
 res = ops->pre_action(substream, state);
 if (res < 0)
  return res;
 res = ops->do_action(substream, state);
 if (res == 0)
  ops->post_action(substream, state);
 else if (ops->undo_action)
  ops->undo_action(substream, state);
 return res;
}

static void snd_pcm_group_assign(struct snd_pcm_substream *substream,
     struct snd_pcm_group *new_group)
{
 substream->group = new_group;
 list_move(&substream->link_list, &new_group->substreams);
}

/*
 * Unref and unlock the group, but keep the stream lock;
 * when the group becomes empty and no longer referred, destroy itself
 */
static void snd_pcm_group_unref(struct snd_pcm_group *group,
    struct snd_pcm_substream *substream)
{
 bool do_free;

 if (!group)
  return;
 do_free = refcount_dec_and_test(&group->refs);
 snd_pcm_group_unlock(group, substream->pcm->nonatomic);
 if (do_free)
  kfree(group);
}

/*
 * Lock the group inside a stream lock and reference it;
 * return the locked group object, or NULL if not linked
 */
static struct snd_pcm_group *
snd_pcm_stream_group_ref(struct snd_pcm_substream *substream)
{
 bool nonatomic = substream->pcm->nonatomic;
 struct snd_pcm_group *group;
 bool trylock;

 for (;;) {
  if (!snd_pcm_stream_linked(substream))
   return NULL;
  group = substream->group;
  /* block freeing the group object */
  refcount_inc(&group->refs);

  trylock = nonatomic ? mutex_trylock(&group->mutex) :
   spin_trylock(&group->lock);
  if (trylock)
   break; /* OK */

  /* re-lock for avoiding ABBA deadlock */
  snd_pcm_stream_unlock(substream);
  snd_pcm_group_lock(group, nonatomic);
  snd_pcm_stream_lock(substream);

  /* check the group again; the above opens a small race window */
  if (substream->group == group)
   break; /* OK */
  /* group changed, try again */
  snd_pcm_group_unref(group, substream);
 }
 return group;
}

/*
 *  Note: call with stream lock
 */
static int snd_pcm_action(const struct action_ops *ops,
     struct snd_pcm_substream *substream,
     snd_pcm_state_t state)
{
 struct snd_pcm_group *group;
 int res;

 group = snd_pcm_stream_group_ref(substream);
 if (group)
  res = snd_pcm_action_group(ops, substream, state, true);
 else
  res = snd_pcm_action_single(ops, substream, state);
 snd_pcm_group_unref(group, substream);
 return res;
}

/*
 *  Note: don't use any locks before
 */
static int snd_pcm_action_lock_irq(const struct action_ops *ops,
       struct snd_pcm_substream *substream,
       snd_pcm_state_t state)
{
 guard(pcm_stream_lock_irq)(substream);
 return snd_pcm_action(ops, substream, state);
}

/*
 */
static int snd_pcm_action_nonatomic(const struct action_ops *ops,
        struct snd_pcm_substream *substream,
        snd_pcm_state_t state)
{
 int res;

 /* Guarantee the group members won't change during non-atomic action */
 guard(rwsem_read)(&snd_pcm_link_rwsem);
 res = snd_pcm_buffer_access_lock(substream->runtime);
 if (res < 0)
  return res;
 if (snd_pcm_stream_linked(substream))
  res = snd_pcm_action_group(ops, substream, state, false);
 else
  res = snd_pcm_action_single(ops, substream, state);
 snd_pcm_buffer_access_unlock(substream->runtime);
 return res;
}

/*
 * start callbacks
 */
static int snd_pcm_pre_start(struct snd_pcm_substream *substream,
        snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (runtime->state != SNDRV_PCM_STATE_PREPARED)
  return -EBADFD;
 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
     !snd_pcm_playback_data(substream))
  return -EPIPE;
 runtime->trigger_tstamp_latched = false;
 runtime->trigger_master = substream;
 return 0;
}

static int snd_pcm_do_start(struct snd_pcm_substream *substream,
       snd_pcm_state_t state)
{
 int err;

 if (substream->runtime->trigger_master != substream)
  return 0;
 err = substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_START);
 /* XRUN happened during the start */
 if (err == -EPIPE)
  __snd_pcm_set_state(substream->runtime, SNDRV_PCM_STATE_XRUN);
 return err;
}

static void snd_pcm_undo_start(struct snd_pcm_substream *substream,
          snd_pcm_state_t state)
{
 if (substream->runtime->trigger_master == substream) {
  substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
  substream->runtime->stop_operating = true;
 }
}

static void snd_pcm_post_start(struct snd_pcm_substream *substream,
          snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 snd_pcm_trigger_tstamp(substream);
 runtime->hw_ptr_jiffies = jiffies;
 runtime->hw_ptr_buffer_jiffies = (runtime->buffer_size * HZ) / 
           runtime->rate;
 __snd_pcm_set_state(runtime, state);
 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
     runtime->silence_size > 0)
  snd_pcm_playback_silence(substream, ULONG_MAX);
 snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTART);
}

static const struct action_ops snd_pcm_action_start = {
 .pre_action = snd_pcm_pre_start,
 .do_action = snd_pcm_do_start,
 .undo_action = snd_pcm_undo_start,
 .post_action = snd_pcm_post_start
};

/**
 * snd_pcm_start - start all linked streams
 * @substream: the PCM substream instance
 *
 * Return: Zero if successful, or a negative error code.
 * The stream lock must be acquired before calling this function.
 */
int snd_pcm_start(struct snd_pcm_substream *substream)
{
 return snd_pcm_action(&snd_pcm_action_start, substream,
         SNDRV_PCM_STATE_RUNNING);
}

/* take the stream lock and start the streams */
static int snd_pcm_start_lock_irq(struct snd_pcm_substream *substream)
{
 return snd_pcm_action_lock_irq(&snd_pcm_action_start, substream,
           SNDRV_PCM_STATE_RUNNING);
}

/*
 * stop callbacks
 */
static int snd_pcm_pre_stop(struct snd_pcm_substream *substream,
       snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (runtime->state == SNDRV_PCM_STATE_OPEN)
  return -EBADFD;
 runtime->trigger_master = substream;
 return 0;
}

static int snd_pcm_do_stop(struct snd_pcm_substream *substream,
      snd_pcm_state_t state)
{
 if (substream->runtime->trigger_master == substream &&
     snd_pcm_running(substream)) {
  substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
  substream->runtime->stop_operating = true;
 }
 return 0; /* unconditionally stop all substreams */
}

static void snd_pcm_post_stop(struct snd_pcm_substream *substream,
         snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (runtime->state != state) {
  snd_pcm_trigger_tstamp(substream);
  __snd_pcm_set_state(runtime, state);
  snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTOP);
 }
 wake_up(&runtime->sleep);
 wake_up(&runtime->tsleep);
}

static const struct action_ops snd_pcm_action_stop = {
 .pre_action = snd_pcm_pre_stop,
 .do_action = snd_pcm_do_stop,
 .post_action = snd_pcm_post_stop
};

/**
 * snd_pcm_stop - try to stop all running streams in the substream group
 * @substream: the PCM substream instance
 * @state: PCM state after stopping the stream
 *
 * The state of each stream is then changed to the given state unconditionally.
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_pcm_stop(struct snd_pcm_substream *substream, snd_pcm_state_t state)
{
 return snd_pcm_action(&snd_pcm_action_stop, substream, state);
}
EXPORT_SYMBOL(snd_pcm_stop);

/**
 * snd_pcm_drain_done - stop the DMA only when the given stream is playback
 * @substream: the PCM substream
 *
 * After stopping, the state is changed to SETUP.
 * Unlike snd_pcm_stop(), this affects only the given stream.
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_pcm_drain_done(struct snd_pcm_substream *substream)
{
 return snd_pcm_action_single(&snd_pcm_action_stop, substream,
         SNDRV_PCM_STATE_SETUP);
}

/**
 * snd_pcm_stop_xrun - stop the running streams as XRUN
 * @substream: the PCM substream instance
 *
 * This stops the given running substream (and all linked substreams) as XRUN.
 * Unlike snd_pcm_stop(), this function takes the substream lock by itself.
 *
 * Return: Zero if successful, or a negative error code.
 */
int snd_pcm_stop_xrun(struct snd_pcm_substream *substream)
{
 guard(pcm_stream_lock_irqsave)(substream);
 if (substream->runtime && snd_pcm_running(substream))
  __snd_pcm_xrun(substream);
 return 0;
}
EXPORT_SYMBOL_GPL(snd_pcm_stop_xrun);

/*
 * pause callbacks: pass boolean (to start pause or resume) as state argument
 */
#define pause_pushed(state) (__force bool)(state)

static int snd_pcm_pre_pause(struct snd_pcm_substream *substream,
        snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (!(runtime->info & SNDRV_PCM_INFO_PAUSE))
  return -ENOSYS;
 if (pause_pushed(state)) {
  if (runtime->state != SNDRV_PCM_STATE_RUNNING)
   return -EBADFD;
 } else if (runtime->state != SNDRV_PCM_STATE_PAUSED)
  return -EBADFD;
 runtime->trigger_master = substream;
 return 0;
}

static int snd_pcm_do_pause(struct snd_pcm_substream *substream,
       snd_pcm_state_t state)
{
 if (substream->runtime->trigger_master != substream)
  return 0;
 /* The jiffies check in snd_pcm_update_hw_ptr*() is done by
 * a delta between the current jiffies, this gives a large enough
 * delta, effectively to skip the check once.
 */
 substream->runtime->hw_ptr_jiffies = jiffies - HZ * 1000;
 return substream->ops->trigger(substream,
           pause_pushed(state) ?
           SNDRV_PCM_TRIGGER_PAUSE_PUSH :
           SNDRV_PCM_TRIGGER_PAUSE_RELEASE);
}

static void snd_pcm_undo_pause(struct snd_pcm_substream *substream,
          snd_pcm_state_t state)
{
 if (substream->runtime->trigger_master == substream)
  substream->ops->trigger(substream,
     pause_pushed(state) ?
     SNDRV_PCM_TRIGGER_PAUSE_RELEASE :
     SNDRV_PCM_TRIGGER_PAUSE_PUSH);
}

static void snd_pcm_post_pause(struct snd_pcm_substream *substream,
          snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 snd_pcm_trigger_tstamp(substream);
 if (pause_pushed(state)) {
  __snd_pcm_set_state(runtime, SNDRV_PCM_STATE_PAUSED);
  snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MPAUSE);
  wake_up(&runtime->sleep);
  wake_up(&runtime->tsleep);
 } else {
  __snd_pcm_set_state(runtime, SNDRV_PCM_STATE_RUNNING);
  snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MCONTINUE);
 }
}

static const struct action_ops snd_pcm_action_pause = {
 .pre_action = snd_pcm_pre_pause,
 .do_action = snd_pcm_do_pause,
 .undo_action = snd_pcm_undo_pause,
 .post_action = snd_pcm_post_pause
};

/*
 * Push/release the pause for all linked streams.
 */
static int snd_pcm_pause(struct snd_pcm_substream *substream, bool push)
{
 return snd_pcm_action(&snd_pcm_action_pause, substream,
         (__force snd_pcm_state_t)push);
}

static int snd_pcm_pause_lock_irq(struct snd_pcm_substream *substream,
      bool push)
{
 return snd_pcm_action_lock_irq(&snd_pcm_action_pause, substream,
           (__force snd_pcm_state_t)push);
}

#ifdef CONFIG_PM
/* suspend callback: state argument ignored */

static int snd_pcm_pre_suspend(struct snd_pcm_substream *substream,
          snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 switch (runtime->state) {
 case SNDRV_PCM_STATE_SUSPENDED:
  return -EBUSY;
 /* unresumable PCM state; return -EBUSY for skipping suspend */
 case SNDRV_PCM_STATE_OPEN:
 case SNDRV_PCM_STATE_SETUP:
 case SNDRV_PCM_STATE_DISCONNECTED:
  return -EBUSY;
 }
 runtime->trigger_master = substream;
 return 0;
}

static int snd_pcm_do_suspend(struct snd_pcm_substream *substream,
         snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (runtime->trigger_master != substream)
  return 0;
 if (! snd_pcm_running(substream))
  return 0;
 substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_SUSPEND);
 runtime->stop_operating = true;
 return 0; /* suspend unconditionally */
}

static void snd_pcm_post_suspend(struct snd_pcm_substream *substream,
     snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 snd_pcm_trigger_tstamp(substream);
 runtime->suspended_state = runtime->state;
 runtime->status->suspended_state = runtime->suspended_state;
 __snd_pcm_set_state(runtime, SNDRV_PCM_STATE_SUSPENDED);
 snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSUSPEND);
 wake_up(&runtime->sleep);
 wake_up(&runtime->tsleep);
}

static const struct action_ops snd_pcm_action_suspend = {
 .pre_action = snd_pcm_pre_suspend,
 .do_action = snd_pcm_do_suspend,
 .post_action = snd_pcm_post_suspend
};

/*
 * snd_pcm_suspend - trigger SUSPEND to all linked streams
 * @substream: the PCM substream
 *
 * After this call, all streams are changed to SUSPENDED state.
 *
 * Return: Zero if successful, or a negative error code.
 */
static int snd_pcm_suspend(struct snd_pcm_substream *substream)
{
 guard(pcm_stream_lock_irqsave)(substream);
 return snd_pcm_action(&snd_pcm_action_suspend, substream,
         ACTION_ARG_IGNORE);
}

/**
 * snd_pcm_suspend_all - trigger SUSPEND to all substreams in the given pcm
 * @pcm: the PCM instance
 *
 * After this call, all streams are changed to SUSPENDED state.
 *
 * Return: Zero if successful (or @pcm is %NULL), or a negative error code.
 */
int snd_pcm_suspend_all(struct snd_pcm *pcm)
{
 struct snd_pcm_substream *substream;
 int stream, err = 0;

 if (! pcm)
  return 0;

 for_each_pcm_substream(pcm, stream, substream) {
  /* FIXME: the open/close code should lock this as well */
  if (!substream->runtime)
   continue;

  /*
 * Skip BE dai link PCM's that are internal and may
 * not have their substream ops set.
 */
  if (!substream->ops)
   continue;

  err = snd_pcm_suspend(substream);
  if (err < 0 && err != -EBUSY)
   return err;
 }

 for_each_pcm_substream(pcm, stream, substream)
  snd_pcm_sync_stop(substream, false);

 return 0;
}
EXPORT_SYMBOL(snd_pcm_suspend_all);

/* resume callbacks: state argument ignored */

static int snd_pcm_pre_resume(struct snd_pcm_substream *substream,
         snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (runtime->state != SNDRV_PCM_STATE_SUSPENDED)
  return -EBADFD;
 if (!(runtime->info & SNDRV_PCM_INFO_RESUME))
  return -ENOSYS;
 runtime->trigger_master = substream;
 return 0;
}

static int snd_pcm_do_resume(struct snd_pcm_substream *substream,
        snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (runtime->trigger_master != substream)
  return 0;
 /* DMA not running previously? */
 if (runtime->suspended_state != SNDRV_PCM_STATE_RUNNING &&
     (runtime->suspended_state != SNDRV_PCM_STATE_DRAINING ||
      substream->stream != SNDRV_PCM_STREAM_PLAYBACK))
  return 0;
 return substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_RESUME);
}

static void snd_pcm_undo_resume(struct snd_pcm_substream *substream,
    snd_pcm_state_t state)
{
 if (substream->runtime->trigger_master == substream &&
     snd_pcm_running(substream))
  substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_SUSPEND);
}

static void snd_pcm_post_resume(struct snd_pcm_substream *substream,
    snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 snd_pcm_trigger_tstamp(substream);
 __snd_pcm_set_state(runtime, runtime->suspended_state);
 snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MRESUME);
}

static const struct action_ops snd_pcm_action_resume = {
 .pre_action = snd_pcm_pre_resume,
 .do_action = snd_pcm_do_resume,
 .undo_action = snd_pcm_undo_resume,
 .post_action = snd_pcm_post_resume
};

static int snd_pcm_resume(struct snd_pcm_substream *substream)
{
 return snd_pcm_action_lock_irq(&snd_pcm_action_resume, substream,
           ACTION_ARG_IGNORE);
}

#else

static int snd_pcm_resume(struct snd_pcm_substream *substream)
{
 return -ENOSYS;
}

#endif /* CONFIG_PM */

/*
 * xrun ioctl
 *
 * Change the RUNNING stream(s) to XRUN state.
 */
static int snd_pcm_xrun(struct snd_pcm_substream *substream)
{
 struct snd_pcm_runtime *runtime = substream->runtime;

 guard(pcm_stream_lock_irq)(substream);
 switch (runtime->state) {
 case SNDRV_PCM_STATE_XRUN:
  return 0; /* already there */
 case SNDRV_PCM_STATE_RUNNING:
  __snd_pcm_xrun(substream);
  return 0;
 default:
  return -EBADFD;
 }
}

/*
 * reset ioctl
 */
/* reset callbacks:  state argument ignored */
static int snd_pcm_pre_reset(struct snd_pcm_substream *substream,
        snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 switch (runtime->state) {
 case SNDRV_PCM_STATE_RUNNING:
 case SNDRV_PCM_STATE_PREPARED:
 case SNDRV_PCM_STATE_PAUSED:
 case SNDRV_PCM_STATE_SUSPENDED:
  return 0;
 default:
  return -EBADFD;
 }
}

static int snd_pcm_do_reset(struct snd_pcm_substream *substream,
       snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 int err = snd_pcm_ops_ioctl(substream, SNDRV_PCM_IOCTL1_RESET, NULL);
 if (err < 0)
  return err;
 guard(pcm_stream_lock_irq)(substream);
 runtime->hw_ptr_base = 0;
 runtime->hw_ptr_interrupt = runtime->status->hw_ptr -
  runtime->status->hw_ptr % runtime->period_size;
 runtime->silence_start = runtime->status->hw_ptr;
 runtime->silence_filled = 0;
 return 0;
}

static void snd_pcm_post_reset(struct snd_pcm_substream *substream,
          snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 guard(pcm_stream_lock_irq)(substream);
 runtime->control->appl_ptr = runtime->status->hw_ptr;
 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
     runtime->silence_size > 0)
  snd_pcm_playback_silence(substream, ULONG_MAX);
}

static const struct action_ops snd_pcm_action_reset = {
 .pre_action = snd_pcm_pre_reset,
 .do_action = snd_pcm_do_reset,
 .post_action = snd_pcm_post_reset
};

static int snd_pcm_reset(struct snd_pcm_substream *substream)
{
 return snd_pcm_action_nonatomic(&snd_pcm_action_reset, substream,
     ACTION_ARG_IGNORE);
}

/*
 * prepare ioctl
 */
/* pass f_flags as state argument */
static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream,
          snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 int f_flags = (__force int)state;

 if (runtime->state == SNDRV_PCM_STATE_OPEN ||
     runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
  return -EBADFD;
 if (snd_pcm_running(substream))
  return -EBUSY;
 substream->f_flags = f_flags;
 return 0;
}

static int snd_pcm_do_prepare(struct snd_pcm_substream *substream,
         snd_pcm_state_t state)
{
 int err;
 snd_pcm_sync_stop(substream, true);
 err = substream->ops->prepare(substream);
 if (err < 0)
  return err;
 return snd_pcm_do_reset(substream, state);
}

static void snd_pcm_post_prepare(struct snd_pcm_substream *substream,
     snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 runtime->control->appl_ptr = runtime->status->hw_ptr;
 snd_pcm_set_state(substream, SNDRV_PCM_STATE_PREPARED);
}

static const struct action_ops snd_pcm_action_prepare = {
 .pre_action = snd_pcm_pre_prepare,
 .do_action = snd_pcm_do_prepare,
 .post_action = snd_pcm_post_prepare
};

/**
 * snd_pcm_prepare - prepare the PCM substream to be triggerable
 * @substream: the PCM substream instance
 * @file: file to refer f_flags
 *
 * Return: Zero if successful, or a negative error code.
 */
static int snd_pcm_prepare(struct snd_pcm_substream *substream,
      struct file *file)
{
 int f_flags;

 if (file)
  f_flags = file->f_flags;
 else
  f_flags = substream->f_flags;

 scoped_guard(pcm_stream_lock_irq, substream) {
  switch (substream->runtime->state) {
  case SNDRV_PCM_STATE_PAUSED:
   snd_pcm_pause(substream, false);
   fallthrough;
  case SNDRV_PCM_STATE_SUSPENDED:
   snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
   break;
  }
 }

 return snd_pcm_action_nonatomic(&snd_pcm_action_prepare,
     substream,
     (__force snd_pcm_state_t)f_flags);
}

/*
 * drain ioctl
 */

/* drain init callbacks: state argument ignored */
static int snd_pcm_pre_drain_init(struct snd_pcm_substream *substream,
      snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 switch (runtime->state) {
 case SNDRV_PCM_STATE_OPEN:
 case SNDRV_PCM_STATE_DISCONNECTED:
 case SNDRV_PCM_STATE_SUSPENDED:
  return -EBADFD;
 }
 runtime->trigger_master = substream;
 return 0;
}

static int snd_pcm_do_drain_init(struct snd_pcm_substream *substream,
     snd_pcm_state_t state)
{
 struct snd_pcm_runtime *runtime = substream->runtime;
 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
  switch (runtime->state) {
  case SNDRV_PCM_STATE_PREPARED:
   /* start playback stream if possible */
   if (! snd_pcm_playback_empty(substream)) {
    snd_pcm_do_start(substream, SNDRV_PCM_STATE_DRAINING);
    snd_pcm_post_start(substream, SNDRV_PCM_STATE_DRAINING);
   } else {
    __snd_pcm_set_state(runtime, SNDRV_PCM_STATE_SETUP);
   }
   break;
  case SNDRV_PCM_STATE_RUNNING:
   __snd_pcm_set_state(runtime, SNDRV_PCM_STATE_DRAINING);
   break;
  case SNDRV_PCM_STATE_XRUN:
   __snd_pcm_set_state(runtime, SNDRV_PCM_STATE_SETUP);
   break;
  default:
   break;
  }
 } else {
  /* stop running stream */
  if (runtime->state == SNDRV_PCM_STATE_RUNNING) {
   snd_pcm_state_t new_state;

   new_state = snd_pcm_capture_avail(runtime) > 0 ?
    SNDRV_PCM_STATE_DRAINING : SNDRV_PCM_STATE_SETUP;
   snd_pcm_do_stop(substream, new_state);
   snd_pcm_post_stop(substream, new_state);
  }
 }

 if (runtime->state == SNDRV_PCM_STATE_DRAINING &&
     runtime->trigger_master == substream &&
     (runtime->hw.info & SNDRV_PCM_INFO_DRAIN_TRIGGER))
  return substream->ops->trigger(substream,
            SNDRV_PCM_TRIGGER_DRAIN);

 return 0;
}

static void snd_pcm_post_drain_init(struct snd_pcm_substream *substream,
        snd_pcm_state_t state)
{
}

static const struct action_ops snd_pcm_action_drain_init = {
 .pre_action = snd_pcm_pre_drain_init,
 .do_action = snd_pcm_do_drain_init,
 .post_action = snd_pcm_post_drain_init
};

/*
 * Drain the stream(s).
 * When the substream is linked, sync until the draining of all playback streams
 * is finished.
 * After this call, all streams are supposed to be either SETUP or DRAINING
 * (capture only) state.
 */
static int snd_pcm_drain(struct snd_pcm_substream *substream,
    struct file *file)
{
 struct snd_card *card;
 struct snd_pcm_runtime *runtime;
 struct snd_pcm_substream *s;
 struct snd_pcm_group *group;
 wait_queue_entry_t wait;
 int result = 0;
 int nonblock = 0;

 card = substream->pcm->card;
 runtime = substream->runtime;

 if (runtime->state == SNDRV_PCM_STATE_OPEN)
  return -EBADFD;

 if (file) {
  if (file->f_flags & O_NONBLOCK)
   nonblock = 1;
 } else if (substream->f_flags & O_NONBLOCK)
  nonblock = 1;

 snd_pcm_stream_lock_irq(substream);
 /* resume pause */
 if (runtime->state == SNDRV_PCM_STATE_PAUSED)
  snd_pcm_pause(substream, false);

 /* pre-start/stop - all running streams are changed to DRAINING state */
 result = snd_pcm_action(&snd_pcm_action_drain_init, substream,
    ACTION_ARG_IGNORE);
 if (result < 0)
  goto unlock;
 /* in non-blocking, we don't wait in ioctl but let caller poll */
 if (nonblock) {
  result = -EAGAIN;
  goto unlock;
 }

 for (;;) {
  long tout;
  struct snd_pcm_runtime *to_check;
  if (signal_pending(current)) {
   result = -ERESTARTSYS;
   break;
  }
  /* find a substream to drain */
  to_check = NULL;
  group = snd_pcm_stream_group_ref(substream);
  snd_pcm_group_for_each_entry(s, substream) {
   if (s->stream != SNDRV_PCM_STREAM_PLAYBACK)
    continue;
   runtime = s->runtime;
   if (runtime->state == SNDRV_PCM_STATE_DRAINING) {
    to_check = runtime;
    break;
   }
  }
  snd_pcm_group_unref(group, substream);
  if (!to_check)
   break; /* all drained */
  init_waitqueue_entry(&wait, current);
  set_current_state(TASK_INTERRUPTIBLE);
  add_wait_queue(&to_check->sleep, &wait);
  snd_pcm_stream_unlock_irq(substream);
  if (runtime->no_period_wakeup)
   tout = MAX_SCHEDULE_TIMEOUT;
  else {
   tout = 100;
   if (runtime->rate) {
    long t = runtime->buffer_size * 1100 / runtime->rate;
    tout = max(t, tout);
   }
   tout = msecs_to_jiffies(tout);
  }
  tout = schedule_timeout(tout);

  snd_pcm_stream_lock_irq(substream);
  group = snd_pcm_stream_group_ref(substream);
  snd_pcm_group_for_each_entry(s, substream) {
   if (s->runtime == to_check) {
    remove_wait_queue(&to_check->sleep, &wait);
    break;
   }
  }
  snd_pcm_group_unref(group, substream);

  if (card->shutdown) {
   result = -ENODEV;
   break;
  }
  if (tout == 0) {
   if (substream->runtime->state == SNDRV_PCM_STATE_SUSPENDED)
    result = -ESTRPIPE;
   else {
    dev_dbg(substream->pcm->card->dev,
     "playback drain timeout (DMA or IRQ trouble?)\n");
    snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
    result = -EIO;
   }
   break;
  }
 }

 unlock:
 snd_pcm_stream_unlock_irq(substream);

 return result;
}

/*
 * drop ioctl
 *
 * Immediately put all linked substreams into SETUP state.
 */
static int snd_pcm_drop(struct snd_pcm_substream *substream)
{
 struct snd_pcm_runtime *runtime;
 int result = 0;
 
 if (PCM_RUNTIME_CHECK(substream))
  return -ENXIO;
 runtime = substream->runtime;

 if (runtime->state == SNDRV_PCM_STATE_OPEN ||
     runtime->state == SNDRV_PCM_STATE_DISCONNECTED)
  return -EBADFD;

 guard(pcm_stream_lock_irq)(substream);
 /* resume pause */
 if (runtime->state == SNDRV_PCM_STATE_PAUSED)
  snd_pcm_pause(substream, false);

 snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
 /* runtime->control->appl_ptr = runtime->status->hw_ptr; */

 return result;
}


static bool is_pcm_file(struct file *file)
{
 struct inode *inode = file_inode(file);
 struct snd_pcm *pcm;
 unsigned int minor;

 if (!S_ISCHR(inode->i_mode) || imajor(inode) != snd_major)
  return false;
 minor = iminor(inode);
 pcm = snd_lookup_minor_data(minor, SNDRV_DEVICE_TYPE_PCM_PLAYBACK);
 if (!pcm)
  pcm = snd_lookup_minor_data(minor, SNDRV_DEVICE_TYPE_PCM_CAPTURE);
 if (!pcm)
  return false;
 snd_card_unref(pcm->card);
 return true;
}

/*
 * PCM link handling
 */
static int snd_pcm_link(struct snd_pcm_substream *substream, int fd)
{
 struct snd_pcm_file *pcm_file;
 struct snd_pcm_substream *substream1;
 struct snd_pcm_group *group __free(kfree) = NULL;
 struct snd_pcm_group *target_group;
 bool nonatomic = substream->pcm->nonatomic;
 CLASS(fd, f)(fd);

 if (fd_empty(f))
  return -EBADFD;
 if (!is_pcm_file(fd_file(f)))
  return -EBADFD;

 pcm_file = fd_file(f)->private_data;
 substream1 = pcm_file->substream;

 if (substream == substream1)
  return -EINVAL;

 group = kzalloc(sizeof(*group), GFP_KERNEL);
 if (!group)
  return -ENOMEM;
 snd_pcm_group_init(group);

 guard(rwsem_write)(&snd_pcm_link_rwsem);
 if (substream->runtime->state == SNDRV_PCM_STATE_OPEN ||
     substream->runtime->state != substream1->runtime->state ||
     substream->pcm->nonatomic != substream1->pcm->nonatomic)
  return -EBADFD;
 if (snd_pcm_stream_linked(substream1))
  return -EALREADY;

 scoped_guard(pcm_stream_lock_irq, substream) {
  if (!snd_pcm_stream_linked(substream)) {
   snd_pcm_group_assign(substream, group);
   group = NULL; /* assigned, don't free this one below */
  }
  target_group = substream->group;
 }

 snd_pcm_group_lock_irq(target_group, nonatomic);
 snd_pcm_stream_lock_nested(substream1);
 snd_pcm_group_assign(substream1, target_group);
 refcount_inc(&target_group->refs);
 snd_pcm_stream_unlock(substream1);
 snd_pcm_group_unlock_irq(target_group, nonatomic);
 return 0;
}

static void relink_to_local(struct snd_pcm_substream *substream)
{
 snd_pcm_stream_lock_nested(substream);
 snd_pcm_group_assign(substream, &substream->self_group);
 snd_pcm_stream_unlock(substream);
}

static int snd_pcm_unlink(struct snd_pcm_substream *substream)
{
 struct snd_pcm_group *group;
 bool nonatomic = substream->pcm->nonatomic;
 bool do_free = false;

 guard(rwsem_write)(&snd_pcm_link_rwsem);

 if (!snd_pcm_stream_linked(substream))
  return -EALREADY;

 group = substream->group;
 snd_pcm_group_lock_irq(group, nonatomic);

 relink_to_local(substream);
 refcount_dec(&group->refs);

 /* detach the last stream, too */
 if (list_is_singular(&group->substreams)) {
  relink_to_local(list_first_entry(&group->substreams,
       struct snd_pcm_substream,
       link_list));
  do_free = refcount_dec_and_test(&group->refs);
 }

 snd_pcm_group_unlock_irq(group, nonatomic);
 if (do_free)
  kfree(group);
 return 0;
}

/*
 * hw configurator
 */
static int snd_pcm_hw_rule_mul(struct snd_pcm_hw_params *params,
          struct snd_pcm_hw_rule *rule)
{
 struct snd_interval t;
 snd_interval_mul(hw_param_interval_c(params, rule->deps[0]),
       hw_param_interval_c(params, rule->deps[1]), &t);
 return snd_interval_refine(hw_param_interval(params, rule->var), &t);
}

static int snd_pcm_hw_rule_div(struct snd_pcm_hw_params *params,
          struct snd_pcm_hw_rule *rule)
{
 struct snd_interval t;
--> --------------------

--> maximum size reached

--> --------------------