blob: d1d56eca1061c7c112fba35a7a39c0c294b72fcb [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * w1_family.c
3 *
4 * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
5 *
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21
22#include <linux/spinlock.h>
23#include <linux/list.h>
24#include <linux/delay.h>
25
26#include "w1_family.h"
27
28DEFINE_SPINLOCK(w1_flock);
29static LIST_HEAD(w1_families);
30
31static int w1_check_family(struct w1_family *f)
32{
33 if (!f->fops->rname || !f->fops->rbin || !f->fops->rval || !f->fops->rvalname)
34 return -EINVAL;
35
36 return 0;
37}
38
39int w1_register_family(struct w1_family *newf)
40{
41 struct list_head *ent, *n;
42 struct w1_family *f;
43 int ret = 0;
44
45 if (w1_check_family(newf))
46 return -EINVAL;
47
48 spin_lock(&w1_flock);
49 list_for_each_safe(ent, n, &w1_families) {
50 f = list_entry(ent, struct w1_family, family_entry);
51
52 if (f->fid == newf->fid) {
53 ret = -EEXIST;
54 break;
55 }
56 }
57
58 if (!ret) {
59 atomic_set(&newf->refcnt, 0);
60 newf->need_exit = 0;
61 list_add_tail(&newf->family_entry, &w1_families);
62 }
63
64 spin_unlock(&w1_flock);
65
66 return ret;
67}
68
69void w1_unregister_family(struct w1_family *fent)
70{
71 struct list_head *ent, *n;
72 struct w1_family *f;
73
74 spin_lock(&w1_flock);
75 list_for_each_safe(ent, n, &w1_families) {
76 f = list_entry(ent, struct w1_family, family_entry);
77
78 if (f->fid == fent->fid) {
79 list_del(&fent->family_entry);
80 break;
81 }
82 }
83
84 fent->need_exit = 1;
85
86 spin_unlock(&w1_flock);
87
88 while (atomic_read(&fent->refcnt)) {
89 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
90 fent->fid, atomic_read(&fent->refcnt));
91
92 if (msleep_interruptible(1000))
93 flush_signals(current);
94 }
95}
96
97/*
98 * Should be called under w1_flock held.
99 */
100struct w1_family * w1_family_registered(u8 fid)
101{
102 struct list_head *ent, *n;
103 struct w1_family *f = NULL;
104 int ret = 0;
105
106 list_for_each_safe(ent, n, &w1_families) {
107 f = list_entry(ent, struct w1_family, family_entry);
108
109 if (f->fid == fid) {
110 ret = 1;
111 break;
112 }
113 }
114
115 return (ret) ? f : NULL;
116}
117
118void w1_family_put(struct w1_family *f)
119{
120 spin_lock(&w1_flock);
121 __w1_family_put(f);
122 spin_unlock(&w1_flock);
123}
124
125void __w1_family_put(struct w1_family *f)
126{
127 if (atomic_dec_and_test(&f->refcnt))
128 f->need_exit = 1;
129}
130
131void w1_family_get(struct w1_family *f)
132{
133 spin_lock(&w1_flock);
134 __w1_family_get(f);
135 spin_unlock(&w1_flock);
136
137}
138
139void __w1_family_get(struct w1_family *f)
140{
141 smp_mb__before_atomic_inc();
142 atomic_inc(&f->refcnt);
143 smp_mb__after_atomic_inc();
144}
145
146EXPORT_SYMBOL(w1_family_get);
147EXPORT_SYMBOL(w1_family_put);
148EXPORT_SYMBOL(w1_family_registered);
149EXPORT_SYMBOL(w1_unregister_family);
150EXPORT_SYMBOL(w1_register_family);