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