1/*
  2 *  net/9p/util.c
  3 *
  4 *  This file contains some helper functions
  5 *
  6 *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
  7 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
  8 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
  9 *
 10 *  This program is free software; you can redistribute it and/or modify
 11 *  it under the terms of the GNU General Public License version 2
 12 *  as published by the Free Software Foundation.
 13 *
 14 *  This program is distributed in the hope that it will be useful,
 15 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 16 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 17 *  GNU General Public License for more details.
 18 *
 19 *  You should have received a copy of the GNU General Public License
 20 *  along with this program; if not, write to:
 21 *  Free Software Foundation
 22 *  51 Franklin Street, Fifth Floor
 23 *  Boston, MA  02111-1301  USA
 24 *
 25 */
 26
 27#include <linux/module.h>
 28#include <linux/errno.h>
 29#include <linux/fs.h>
 30#include <linux/sched.h>
 31#include <linux/parser.h>
 32#include <linux/idr.h>
 33#include <linux/slab.h>
 34#include <net/9p/9p.h>
 35
 36/**
 37 * struct p9_idpool - per-connection accounting for tag idpool
 38 * @lock: protects the pool
 39 * @pool: idr to allocate tag id from
 40 *
 41 */
 42
 43struct p9_idpool {
 44	spinlock_t lock;
 45	struct idr pool;
 46};
 47
 48/**
 49 * p9_idpool_create - create a new per-connection id pool
 50 *
 51 */
 52
 53struct p9_idpool *p9_idpool_create(void)
 54{
 55	struct p9_idpool *p;
 56
 57	p = kmalloc(sizeof(struct p9_idpool), GFP_KERNEL);
 58	if (!p)
 59		return ERR_PTR(-ENOMEM);
 60
 61	spin_lock_init(&p->lock);
 62	idr_init(&p->pool);
 63
 64	return p;
 65}
 66EXPORT_SYMBOL(p9_idpool_create);
 67
 68/**
 69 * p9_idpool_destroy - create a new per-connection id pool
 70 * @p: idpool to destroy
 71 */
 72
 73void p9_idpool_destroy(struct p9_idpool *p)
 74{
 75	idr_destroy(&p->pool);
 76	kfree(p);
 77}
 78EXPORT_SYMBOL(p9_idpool_destroy);
 79
 80/**
 81 * p9_idpool_get - allocate numeric id from pool
 82 * @p: pool to allocate from
 83 *
 84 * Bugs: This seems to be an awful generic function, should it be in idr.c with
 85 *            the lock included in struct idr?
 86 */
 87
 88int p9_idpool_get(struct p9_idpool *p)
 89{
 90	int i = 0;
 91	int error;
 92	unsigned long flags;
 93
 94retry:
 95	if (idr_pre_get(&p->pool, GFP_NOFS) == 0)
 96		return -1;
 97
 98	spin_lock_irqsave(&p->lock, flags);
 99
100	/* no need to store exactly p, we just need something non-null */
101	error = idr_get_new(&p->pool, p, &i);
102	spin_unlock_irqrestore(&p->lock, flags);
103
104	if (error == -EAGAIN)
105		goto retry;
106	else if (error)
107		return -1;
108
109	P9_DPRINTK(P9_DEBUG_MUX, " id %d pool %p\n", i, p);
110	return i;
111}
112EXPORT_SYMBOL(p9_idpool_get);
113
114/**
115 * p9_idpool_put - release numeric id from pool
116 * @id: numeric id which is being released
117 * @p: pool to release id into
118 *
119 * Bugs: This seems to be an awful generic function, should it be in idr.c with
120 *            the lock included in struct idr?
121 */
122
123void p9_idpool_put(int id, struct p9_idpool *p)
124{
125	unsigned long flags;
126
127	P9_DPRINTK(P9_DEBUG_MUX, " id %d pool %p\n", id, p);
128
129	spin_lock_irqsave(&p->lock, flags);
130	idr_remove(&p->pool, id);
131	spin_unlock_irqrestore(&p->lock, flags);
132}
133EXPORT_SYMBOL(p9_idpool_put);
134
135/**
136 * p9_idpool_check - check if the specified id is available
137 * @id: id to check
138 * @p: pool to check
139 */
140
141int p9_idpool_check(int id, struct p9_idpool *p)
142{
143	return idr_find(&p->pool, id) != NULL;
144}
145EXPORT_SYMBOL(p9_idpool_check);
146