9p: implement proper trans module refcounting and unregistration
[linux-2.6.git] / net / 9p / mod.c
1 /*
2  *  net/9p/9p.c
3  *
4  *  9P entry point
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/moduleparam.h>
29 #include <net/9p/9p.h>
30 #include <linux/fs.h>
31 #include <linux/parser.h>
32 #include <net/9p/transport.h>
33 #include <linux/list.h>
34 #include <linux/spinlock.h>
35
36 #ifdef CONFIG_NET_9P_DEBUG
37 unsigned int p9_debug_level = 0;        /* feature-rific global debug level  */
38 EXPORT_SYMBOL(p9_debug_level);
39 module_param_named(debug, p9_debug_level, uint, 0);
40 MODULE_PARM_DESC(debug, "9P debugging level");
41 #endif
42
43 /*
44  * Dynamic Transport Registration Routines
45  *
46  */
47
48 static DEFINE_SPINLOCK(v9fs_trans_lock);
49 static LIST_HEAD(v9fs_trans_list);
50
51 /**
52  * v9fs_register_trans - register a new transport with 9p
53  * @m: structure describing the transport module and entry points
54  *
55  */
56 void v9fs_register_trans(struct p9_trans_module *m)
57 {
58         spin_lock(&v9fs_trans_lock);
59         list_add_tail(&m->list, &v9fs_trans_list);
60         spin_unlock(&v9fs_trans_lock);
61 }
62 EXPORT_SYMBOL(v9fs_register_trans);
63
64 /**
65  * v9fs_unregister_trans - unregister a 9p transport
66  * @m: the transport to remove
67  *
68  */
69 void v9fs_unregister_trans(struct p9_trans_module *m)
70 {
71         spin_lock(&v9fs_trans_lock);
72         list_del_init(&m->list);
73         spin_unlock(&v9fs_trans_lock);
74 }
75 EXPORT_SYMBOL(v9fs_unregister_trans);
76
77 /**
78  * v9fs_get_trans_by_name - get transport with the matching name
79  * @name: string identifying transport
80  *
81  */
82 struct p9_trans_module *v9fs_get_trans_by_name(const substring_t *name)
83 {
84         struct p9_trans_module *t, *found = NULL;
85
86         spin_lock(&v9fs_trans_lock);
87
88         list_for_each_entry(t, &v9fs_trans_list, list)
89                 if (strncmp(t->name, name->from, name->to-name->from) == 0 &&
90                     try_module_get(t->owner)) {
91                         found = t;
92                         break;
93                 }
94
95         spin_unlock(&v9fs_trans_lock);
96         return found;
97 }
98 EXPORT_SYMBOL(v9fs_get_trans_by_name);
99
100 /**
101  * v9fs_get_default_trans - get the default transport
102  *
103  */
104
105 struct p9_trans_module *v9fs_get_default_trans(void)
106 {
107         struct p9_trans_module *t, *found = NULL;
108
109         spin_lock(&v9fs_trans_lock);
110
111         list_for_each_entry(t, &v9fs_trans_list, list)
112                 if (t->def && try_module_get(t->owner)) {
113                         found = t;
114                         break;
115                 }
116
117         if (!found)
118                 list_for_each_entry(t, &v9fs_trans_list, list)
119                         if (try_module_get(t->owner)) {
120                                 found = t;
121                                 break;
122                         }
123
124         spin_unlock(&v9fs_trans_lock);
125         return found;
126 }
127 EXPORT_SYMBOL(v9fs_get_default_trans);
128
129 /**
130  * v9fs_put_trans - put trans
131  * @m: transport to put
132  *
133  */
134 void v9fs_put_trans(struct p9_trans_module *m)
135 {
136         if (m)
137                 module_put(m->owner);
138 }
139
140 /**
141  * v9fs_init - Initialize module
142  *
143  */
144 static int __init init_p9(void)
145 {
146         int ret = 0;
147
148         p9_error_init();
149         printk(KERN_INFO "Installing 9P2000 support\n");
150         p9_trans_fd_init();
151
152         return ret;
153 }
154
155 /**
156  * v9fs_init - shutdown module
157  *
158  */
159
160 static void __exit exit_p9(void)
161 {
162         printk(KERN_INFO "Unloading 9P2000 support\n");
163
164         p9_trans_fd_exit();
165 }
166
167 module_init(init_p9)
168 module_exit(exit_p9)
169
170 MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
171 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
172 MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
173 MODULE_LICENSE("GPL");