/*
   *  net/9p/util.c
   *
   *  This file contains some helper functions
   *
   *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
   *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License version 2
   *  as published by the Free Software Foundation.
   *
   *  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:
   *  Free Software Foundation
   *  51 Franklin Street, Fifth Floor
   *  Boston, MA  02111-1301  USA
   *
   */
  
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/fs.h>
  #include <linux/sched.h>
  #include <linux/parser.h>
  #include <linux/idr.h>
  #include <linux/slab.h>
  #include <net/9p/9p.h>
  
  /**
   * struct p9_idpool - per-connection accounting for tag idpool
   * @lock: protects the pool
   * @pool: idr to allocate tag id from
   *
   */
  
  struct p9_idpool {
  	spinlock_t lock;
  	struct idr pool;
  };
  
  /**
   * p9_idpool_create - create a new per-connection id pool
   *
   */
  
  struct p9_idpool *p9_idpool_create(void)
  {
  	struct p9_idpool *p;
  
  	p = kmalloc(sizeof(struct p9_idpool), GFP_KERNEL);
  	if (!p)
  		return ERR_PTR(-ENOMEM);
  
  	spin_lock_init(&p->lock);
  	idr_init(&p->pool);
  
  	return p;
  }
  EXPORT_SYMBOL(p9_idpool_create);
  
  /**
   * p9_idpool_destroy - create a new per-connection id pool
   * @p: idpool to destroy
   */
  
  void p9_idpool_destroy(struct p9_idpool *p)
  {
  	idr_destroy(&p->pool);
  	kfree(p);
  }
  EXPORT_SYMBOL(p9_idpool_destroy);
  
  /**
   * p9_idpool_get - allocate numeric id from pool
   * @p: pool to allocate from
   *
   * Bugs: This seems to be an awful generic function, should it be in idr.c with
   *            the lock included in struct idr?
   */
  
  int p9_idpool_get(struct p9_idpool *p)
  {
  	int i;
  	unsigned long flags;
  
  	idr_preload(GFP_NOFS);
  	spin_lock_irqsave(&p->lock, flags);
  
  	/* no need to store exactly p, we just need something non-null */
  	i = idr_alloc(&p->pool, p, 0, 0, GFP_NOWAIT);
  
  	spin_unlock_irqrestore(&p->lock, flags);
  	idr_preload_end();
  	if (i < 0)
  		return -1;
  
  	p9_debug(P9_DEBUG_MUX, " id %d pool %p
  ", i, p);
  	return i;
  }
  EXPORT_SYMBOL(p9_idpool_get);
  
  /**
   * p9_idpool_put - release numeric id from pool
   * @id: numeric id which is being released
   * @p: pool to release id into
   *
   * Bugs: This seems to be an awful generic function, should it be in idr.c with
   *            the lock included in struct idr?
   */
  
  void p9_idpool_put(int id, struct p9_idpool *p)
  {
  	unsigned long flags;
  
  	p9_debug(P9_DEBUG_MUX, " id %d pool %p
  ", id, p);
  
  	spin_lock_irqsave(&p->lock, flags);
  	idr_remove(&p->pool, id);
  	spin_unlock_irqrestore(&p->lock, flags);
  }
  EXPORT_SYMBOL(p9_idpool_put);
  
  /**
   * p9_idpool_check - check if the specified id is available
   * @id: id to check
   * @p: pool to check
   */
  
  int p9_idpool_check(int id, struct p9_idpool *p)
  {
  	return idr_find(&p->pool, id) != NULL;
  }
  EXPORT_SYMBOL(p9_idpool_check);