1 /*
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/sched.h> /* schedule_timeout() */
25 #include <linux/delay.h>
26
27 #include "w1_family.h"
28 #include "w1.h"
29
30 DEFINE_SPINLOCK(w1_flock);
31 static LIST_HEAD(w1_families);
32
33 int w1_register_family(struct w1_family *newf)
34 {
35 struct list_head *ent, *n;
36 struct w1_family *f;
37 int ret = 0;
38
39 spin_lock(&w1_flock);
40 list_for_each_safe(ent, n, &w1_families) {
41 f = list_entry(ent, struct w1_family, family_entry);
42
43 if (f->fid == newf->fid) {
44 ret = -EEXIST;
45 break;
46 }
47 }
48
49 if (!ret) {
50 atomic_set(&newf->refcnt, 0);
51 newf->need_exit = 0;
52 list_add_tail(&newf->family_entry, &w1_families);
53 }
54 spin_unlock(&w1_flock);
55
56 w1_reconnect_slaves(newf);
57
58 return ret;
59 }
60
61 void w1_unregister_family(struct w1_family *fent)
62 {
63 struct list_head *ent, *n;
64 struct w1_family *f;
65
66 spin_lock(&w1_flock);
67 list_for_each_safe(ent, n, &w1_families) {
68 f = list_entry(ent, struct w1_family, family_entry);
69
70 if (f->fid == fent->fid) {
71 list_del(&fent->family_entry);
72 break;
73 }
74 }
75
76 fent->need_exit = 1;
77
78 spin_unlock(&w1_flock);
79
80 while (atomic_read(&fent->refcnt)) {
81 printk(KERN_INFO "Waiting for family %u to become free: refcnt=%d.\n",
82 fent->fid, atomic_read(&fent->refcnt));
83
84 if (msleep_interruptible(1000))
85 flush_signals(current);
86 }
87 }
88
89 /*
90 * Should be called under w1_flock held.
91 */
92 struct w1_family * w1_family_registered(u8 fid)
93 {
94 struct list_head *ent, *n;
95 struct w1_family *f = NULL;
96 int ret = 0;
97
98 list_for_each_safe(ent, n, &w1_families) {
99 f = list_entry(ent, struct w1_family, family_entry);
100
101 if (f->fid == fid) {
102 ret = 1;
103 break;
104 }
105 }
106
107 return (ret) ? f : NULL;
108 }
109
110 static void __w1_family_put(struct w1_family *f)
111 {
112 if (atomic_dec_and_test(&f->refcnt))
113 f->need_exit = 1;
114 }
115
116 void w1_family_put(struct w1_family *f)
117 {
118 spin_lock(&w1_flock);
119 __w1_family_put(f);
120 spin_unlock(&w1_flock);
121 }
122
123 #if 0
124 void w1_family_get(struct w1_family *f)
125 {
126 spin_lock(&w1_flock);
127 __w1_family_get(f);
128 spin_unlock(&w1_flock);
129 }
130 #endif /* 0 */
131
132 void __w1_family_get(struct w1_family *f)
133 {
134 smp_mb__before_atomic_inc();
135 atomic_inc(&f->refcnt);
136 smp_mb__after_atomic_inc();
137 }
138
139 EXPORT_SYMBOL(w1_unregister_family);
140 EXPORT_SYMBOL(w1_register_family);
141
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