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 destory
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_KERNEL) == 0)
96		return 0;
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