text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *  ALSA sequencer Memory Manager
   *  Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
   *                        Jaroslav Kysela <perex@perex.cz>
   *                2000 by Takashi Iwai <tiwai@suse.de>
   */
  
  #include <linux/init.h>
  #include <linux/export.h>
  #include <linux/slab.h>
  #include <linux/sched/signal.h>
  #include <linux/mm.h>
  #include <sound/core.h>
  
  #include <sound/seq_kernel.h>
  #include "seq_memory.h"
  #include "seq_queue.h"
  #include "seq_info.h"
  #include "seq_lock.h"
  
  static inline int snd_seq_pool_available(struct snd_seq_pool *pool)
  {
  	return pool->total_elements - atomic_read(&pool->counter);
  }
  
  static inline int snd_seq_output_ok(struct snd_seq_pool *pool)
  {
  	return snd_seq_pool_available(pool) >= pool->room;
  }
  
  /*
   * Variable length event:
   * The event like sysex uses variable length type.
   * The external data may be stored in three different formats.
   * 1) kernel space
   *    This is the normal case.
   *      ext.data.len = length
   *      ext.data.ptr = buffer pointer
   * 2) user space
   *    When an event is generated via read(), the external data is
   *    kept in user space until expanded.
   *      ext.data.len = length | SNDRV_SEQ_EXT_USRPTR
   *      ext.data.ptr = userspace pointer
   * 3) chained cells
   *    When the variable length event is enqueued (in prioq or fifo),
   *    the external data is decomposed to several cells.
   *      ext.data.len = length | SNDRV_SEQ_EXT_CHAINED
   *      ext.data.ptr = the additiona cell head
   *         -> cell.next -> cell.next -> ..
   */
  
  /*
   * exported:
   * call dump function to expand external data.
   */
  
  static int get_var_len(const struct snd_seq_event *event)
  {
  	if ((event->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
  		return -EINVAL;
  
  	return event->data.ext.len & ~SNDRV_SEQ_EXT_MASK;
  }
  
  int snd_seq_dump_var_event(const struct snd_seq_event *event,
  			   snd_seq_dump_func_t func, void *private_data)
  {
  	int len, err;
  	struct snd_seq_event_cell *cell;
  
  	len = get_var_len(event);
  	if (len <= 0)
  		return len;
  
  	if (event->data.ext.len & SNDRV_SEQ_EXT_USRPTR) {
  		char buf[32];
  		char __user *curptr = (char __force __user *)event->data.ext.ptr;
  		while (len > 0) {
  			int size = sizeof(buf);
  			if (len < size)
  				size = len;
  			if (copy_from_user(buf, curptr, size))
  				return -EFAULT;
  			err = func(private_data, buf, size);
  			if (err < 0)
  				return err;
  			curptr += size;
  			len -= size;
  		}
  		return 0;
  	}
  	if (!(event->data.ext.len & SNDRV_SEQ_EXT_CHAINED))
  		return func(private_data, event->data.ext.ptr, len);
  
  	cell = (struct snd_seq_event_cell *)event->data.ext.ptr;
  	for (; len > 0 && cell; cell = cell->next) {
  		int size = sizeof(struct snd_seq_event);
  		if (len < size)
  			size = len;
  		err = func(private_data, &cell->event, size);
  		if (err < 0)
  			return err;
  		len -= size;
  	}
  	return 0;
  }
  EXPORT_SYMBOL(snd_seq_dump_var_event);
  
  
  /*
   * exported:
   * expand the variable length event to linear buffer space.
   */
  
  static int seq_copy_in_kernel(char **bufptr, const void *src, int size)
  {
  	memcpy(*bufptr, src, size);
  	*bufptr += size;
  	return 0;
  }
  
  static int seq_copy_in_user(char __user **bufptr, const void *src, int size)
  {
  	if (copy_to_user(*bufptr, src, size))
  		return -EFAULT;
  	*bufptr += size;
  	return 0;
  }
  
  int snd_seq_expand_var_event(const struct snd_seq_event *event, int count, char *buf,
  			     int in_kernel, int size_aligned)
  {
  	int len, newlen;
  	int err;
  
  	len = get_var_len(event);
  	if (len < 0)
  		return len;
  	newlen = len;
  	if (size_aligned > 0)
  		newlen = roundup(len, size_aligned);
  	if (count < newlen)
  		return -EAGAIN;
  
  	if (event->data.ext.len & SNDRV_SEQ_EXT_USRPTR) {
  		if (! in_kernel)
  			return -EINVAL;
  		if (copy_from_user(buf, (void __force __user *)event->data.ext.ptr, len))
  			return -EFAULT;
  		return newlen;
  	}
  	err = snd_seq_dump_var_event(event,
  				     in_kernel ? (snd_seq_dump_func_t)seq_copy_in_kernel :
  				     (snd_seq_dump_func_t)seq_copy_in_user,
  				     &buf);
  	return err < 0 ? err : newlen;
  }
  EXPORT_SYMBOL(snd_seq_expand_var_event);
  
  /*
   * release this cell, free extended data if available
   */
  
  static inline void free_cell(struct snd_seq_pool *pool,
  			     struct snd_seq_event_cell *cell)
  {
  	cell->next = pool->free;
  	pool->free = cell;
  	atomic_dec(&pool->counter);
  }
  
  void snd_seq_cell_free(struct snd_seq_event_cell * cell)
  {
  	unsigned long flags;
  	struct snd_seq_pool *pool;
  
  	if (snd_BUG_ON(!cell))
  		return;
  	pool = cell->pool;
  	if (snd_BUG_ON(!pool))
  		return;
  
  	spin_lock_irqsave(&pool->lock, flags);
  	free_cell(pool, cell);
  	if (snd_seq_ev_is_variable(&cell->event)) {
  		if (cell->event.data.ext.len & SNDRV_SEQ_EXT_CHAINED) {
  			struct snd_seq_event_cell *curp, *nextptr;
  			curp = cell->event.data.ext.ptr;
  			for (; curp; curp = nextptr) {
  				nextptr = curp->next;
  				curp->next = pool->free;
  				free_cell(pool, curp);
  			}
  		}
  	}
  	if (waitqueue_active(&pool->output_sleep)) {
  		/* has enough space now? */
  		if (snd_seq_output_ok(pool))
  			wake_up(&pool->output_sleep);
  	}
  	spin_unlock_irqrestore(&pool->lock, flags);
  }
  
  
  /*
   * allocate an event cell.
   */
  static int snd_seq_cell_alloc(struct snd_seq_pool *pool,
  			      struct snd_seq_event_cell **cellp,
  			      int nonblock, struct file *file,
  			      struct mutex *mutexp)
  {
  	struct snd_seq_event_cell *cell;
  	unsigned long flags;
  	int err = -EAGAIN;
  	wait_queue_entry_t wait;
  
  	if (pool == NULL)
  		return -EINVAL;
  
  	*cellp = NULL;
  
  	init_waitqueue_entry(&wait, current);
  	spin_lock_irqsave(&pool->lock, flags);
  	if (pool->ptr == NULL) {	/* not initialized */
  		pr_debug("ALSA: seq: pool is not initialized\n");
  		err = -EINVAL;
  		goto __error;
  	}
  	while (pool->free == NULL && ! nonblock && ! pool->closing) {
  
  		set_current_state(TASK_INTERRUPTIBLE);
  		add_wait_queue(&pool->output_sleep, &wait);
  		spin_unlock_irqrestore(&pool->lock, flags);
  		if (mutexp)
  			mutex_unlock(mutexp);
  		schedule();
  		if (mutexp)
  			mutex_lock(mutexp);
  		spin_lock_irqsave(&pool->lock, flags);
  		remove_wait_queue(&pool->output_sleep, &wait);
  		/* interrupted? */
  		if (signal_pending(current)) {
  			err = -ERESTARTSYS;
  			goto __error;
  		}
  	}
  	if (pool->closing) { /* closing.. */
  		err = -ENOMEM;
  		goto __error;
  	}
  
  	cell = pool->free;
  	if (cell) {
  		int used;
  		pool->free = cell->next;
  		atomic_inc(&pool->counter);
  		used = atomic_read(&pool->counter);
  		if (pool->max_used < used)
  			pool->max_used = used;
  		pool->event_alloc_success++;
  		/* clear cell pointers */
  		cell->next = NULL;
  		err = 0;
  	} else
  		pool->event_alloc_failures++;
  	*cellp = cell;
  
  __error:
  	spin_unlock_irqrestore(&pool->lock, flags);
  	return err;
  }
  
  
  /*
   * duplicate the event to a cell.
   * if the event has external data, the data is decomposed to additional
   * cells.
   */
  int snd_seq_event_dup(struct snd_seq_pool *pool, struct snd_seq_event *event,
  		      struct snd_seq_event_cell **cellp, int nonblock,
  		      struct file *file, struct mutex *mutexp)
  {
  	int ncells, err;
  	unsigned int extlen;
  	struct snd_seq_event_cell *cell;
  
  	*cellp = NULL;
  
  	ncells = 0;
  	extlen = 0;
  	if (snd_seq_ev_is_variable(event)) {
  		extlen = event->data.ext.len & ~SNDRV_SEQ_EXT_MASK;
  		ncells = DIV_ROUND_UP(extlen, sizeof(struct snd_seq_event));
  	}
  	if (ncells >= pool->total_elements)
  		return -ENOMEM;
  
  	err = snd_seq_cell_alloc(pool, &cell, nonblock, file, mutexp);
  	if (err < 0)
  		return err;
  
  	/* copy the event */
  	cell->event = *event;
  
  	/* decompose */
  	if (snd_seq_ev_is_variable(event)) {
  		int len = extlen;
  		int is_chained = event->data.ext.len & SNDRV_SEQ_EXT_CHAINED;
  		int is_usrptr = event->data.ext.len & SNDRV_SEQ_EXT_USRPTR;
  		struct snd_seq_event_cell *src, *tmp, *tail;
  		char *buf;
  
  		cell->event.data.ext.len = extlen | SNDRV_SEQ_EXT_CHAINED;
  		cell->event.data.ext.ptr = NULL;
  
  		src = (struct snd_seq_event_cell *)event->data.ext.ptr;
  		buf = (char *)event->data.ext.ptr;
  		tail = NULL;
  
  		while (ncells-- > 0) {
  			int size = sizeof(struct snd_seq_event);
  			if (len < size)
  				size = len;
  			err = snd_seq_cell_alloc(pool, &tmp, nonblock, file,
  						 mutexp);
  			if (err < 0)
  				goto __error;
  			if (cell->event.data.ext.ptr == NULL)
  				cell->event.data.ext.ptr = tmp;
  			if (tail)
  				tail->next = tmp;
  			tail = tmp;
  			/* copy chunk */
  			if (is_chained && src) {
  				tmp->event = src->event;
  				src = src->next;
  			} else if (is_usrptr) {
  				if (copy_from_user(&tmp->event, (char __force __user *)buf, size)) {
  					err = -EFAULT;
  					goto __error;
  				}
  			} else {
  				memcpy(&tmp->event, buf, size);
  			}
  			buf += size;
  			len -= size;
  		}
  	}
  
  	*cellp = cell;
  	return 0;
  
  __error:
  	snd_seq_cell_free(cell);
  	return err;
  }
    
  
  /* poll wait */
  int snd_seq_pool_poll_wait(struct snd_seq_pool *pool, struct file *file,
  			   poll_table *wait)
  {
  	poll_wait(file, &pool->output_sleep, wait);
  	return snd_seq_output_ok(pool);
  }
  
  
  /* allocate room specified number of events */
  int snd_seq_pool_init(struct snd_seq_pool *pool)
  {
  	int cell;
  	struct snd_seq_event_cell *cellptr;
  
  	if (snd_BUG_ON(!pool))
  		return -EINVAL;
  
  	cellptr = kvmalloc_array(sizeof(struct snd_seq_event_cell), pool->size,
  				 GFP_KERNEL);
  	if (!cellptr)
  		return -ENOMEM;
  
  	/* add new cells to the free cell list */
  	spin_lock_irq(&pool->lock);
  	if (pool->ptr) {
  		spin_unlock_irq(&pool->lock);
  		kvfree(cellptr);
  		return 0;
  	}
  
  	pool->ptr = cellptr;
  	pool->free = NULL;
  
  	for (cell = 0; cell < pool->size; cell++) {
  		cellptr = pool->ptr + cell;
  		cellptr->pool = pool;
  		cellptr->next = pool->free;
  		pool->free = cellptr;
  	}
  	pool->room = (pool->size + 1) / 2;
  
  	/* init statistics */
  	pool->max_used = 0;
  	pool->total_elements = pool->size;
  	spin_unlock_irq(&pool->lock);
  	return 0;
  }
  
  /* refuse the further insertion to the pool */
  void snd_seq_pool_mark_closing(struct snd_seq_pool *pool)
  {
  	unsigned long flags;
  
  	if (snd_BUG_ON(!pool))
  		return;
  	spin_lock_irqsave(&pool->lock, flags);
  	pool->closing = 1;
  	spin_unlock_irqrestore(&pool->lock, flags);
  }
  
  /* remove events */
  int snd_seq_pool_done(struct snd_seq_pool *pool)
  {
  	struct snd_seq_event_cell *ptr;
  
  	if (snd_BUG_ON(!pool))
  		return -EINVAL;
  
  	/* wait for closing all threads */
  	if (waitqueue_active(&pool->output_sleep))
  		wake_up(&pool->output_sleep);
  
  	while (atomic_read(&pool->counter) > 0)
  		schedule_timeout_uninterruptible(1);
  	
  	/* release all resources */
  	spin_lock_irq(&pool->lock);
  	ptr = pool->ptr;
  	pool->ptr = NULL;
  	pool->free = NULL;
  	pool->total_elements = 0;
  	spin_unlock_irq(&pool->lock);
  
  	kvfree(ptr);
  
  	spin_lock_irq(&pool->lock);
  	pool->closing = 0;
  	spin_unlock_irq(&pool->lock);
  
  	return 0;
  }
  
  
  /* init new memory pool */
  struct snd_seq_pool *snd_seq_pool_new(int poolsize)
  {
  	struct snd_seq_pool *pool;
  
  	/* create pool block */
  	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
  	if (!pool)
  		return NULL;
  	spin_lock_init(&pool->lock);
  	pool->ptr = NULL;
  	pool->free = NULL;
  	pool->total_elements = 0;
  	atomic_set(&pool->counter, 0);
  	pool->closing = 0;
  	init_waitqueue_head(&pool->output_sleep);
  	
  	pool->size = poolsize;
  
  	/* init statistics */
  	pool->max_used = 0;
  	return pool;
  }
  
  /* remove memory pool */
  int snd_seq_pool_delete(struct snd_seq_pool **ppool)
  {
  	struct snd_seq_pool *pool = *ppool;
  
  	*ppool = NULL;
  	if (pool == NULL)
  		return 0;
  	snd_seq_pool_mark_closing(pool);
  	snd_seq_pool_done(pool);
  	kfree(pool);
  	return 0;
  }
  
  /* exported to seq_clientmgr.c */
  void snd_seq_info_pool(struct snd_info_buffer *buffer,
  		       struct snd_seq_pool *pool, char *space)
  {
  	if (pool == NULL)
  		return;
  	snd_iprintf(buffer, "%sPool size          : %d\n", space, pool->total_elements);
  	snd_iprintf(buffer, "%sCells in use       : %d\n", space, atomic_read(&pool->counter));
  	snd_iprintf(buffer, "%sPeak cells in use  : %d\n", space, pool->max_used);
  	snd_iprintf(buffer, "%sAlloc success      : %d\n", space, pool->event_alloc_success);
  	snd_iprintf(buffer, "%sAlloc failures     : %d\n", space, pool->event_alloc_failures);
  }
  