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 <net/9p/9p.h>
34
35 /**
36 * struct p9_idpool - per-connection accounting for tag idpool
37 * @lock: protects the pool
38 * @pool: idr to allocate tag id from
39 *
40 */
41
42 struct p9_idpool {
43 spinlock_t lock;
44 struct idr pool;
45 };
46
47 /**
48 * p9_idpool_create - create a new per-connection id pool
49 *
50 */
51
p9_idpool_create(void)52 struct p9_idpool *p9_idpool_create(void)
53 {
54 struct p9_idpool *p;
55
56 p = kmalloc(sizeof(struct p9_idpool), GFP_KERNEL);
57 if (!p)
58 return ERR_PTR(-ENOMEM);
59
60 spin_lock_init(&p->lock);
61 idr_init(&p->pool);
62
63 return p;
64 }
65 EXPORT_SYMBOL(p9_idpool_create);
66
67 /**
68 * p9_idpool_destroy - create a new per-connection id pool
69 * @p: idpool to destory
70 */
71
p9_idpool_destroy(struct p9_idpool * p)72 void p9_idpool_destroy(struct p9_idpool *p)
73 {
74 idr_destroy(&p->pool);
75 kfree(p);
76 }
77 EXPORT_SYMBOL(p9_idpool_destroy);
78
79 /**
80 * p9_idpool_get - allocate numeric id from pool
81 * @p: pool to allocate from
82 *
83 * Bugs: This seems to be an awful generic function, should it be in idr.c with
84 * the lock included in struct idr?
85 */
86
p9_idpool_get(struct p9_idpool * p)87 int p9_idpool_get(struct p9_idpool *p)
88 {
89 int i = 0;
90 int error;
91 unsigned long flags;
92
93 retry:
94 if (idr_pre_get(&p->pool, GFP_KERNEL) == 0)
95 return 0;
96
97 spin_lock_irqsave(&p->lock, flags);
98
99 /* no need to store exactly p, we just need something non-null */
100 error = idr_get_new(&p->pool, p, &i);
101 spin_unlock_irqrestore(&p->lock, flags);
102
103 if (error == -EAGAIN)
104 goto retry;
105 else if (error)
106 return -1;
107
108 P9_DPRINTK(P9_DEBUG_MUX, " id %d pool %p\n", i, p);
109 return i;
110 }
111 EXPORT_SYMBOL(p9_idpool_get);
112
113 /**
114 * p9_idpool_put - release numeric id from pool
115 * @id: numeric id which is being released
116 * @p: pool to release id into
117 *
118 * Bugs: This seems to be an awful generic function, should it be in idr.c with
119 * the lock included in struct idr?
120 */
121
p9_idpool_put(int id,struct p9_idpool * p)122 void p9_idpool_put(int id, struct p9_idpool *p)
123 {
124 unsigned long flags;
125
126 P9_DPRINTK(P9_DEBUG_MUX, " id %d pool %p\n", id, p);
127
128 spin_lock_irqsave(&p->lock, flags);
129 idr_remove(&p->pool, id);
130 spin_unlock_irqrestore(&p->lock, flags);
131 }
132 EXPORT_SYMBOL(p9_idpool_put);
133
134 /**
135 * p9_idpool_check - check if the specified id is available
136 * @id: id to check
137 * @p: pool to check
138 */
139
p9_idpool_check(int id,struct p9_idpool * p)140 int p9_idpool_check(int id, struct p9_idpool *p)
141 {
142 return idr_find(&p->pool, id) != NULL;
143 }
144 EXPORT_SYMBOL(p9_idpool_check);
145
146