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1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  net/9p/9p.c
4  *
5  *  9P entry point
6  *
7  *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
8  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
9  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/module.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
17 #include <linux/moduleparam.h>
18 #include <net/9p/9p.h>
19 #include <linux/fs.h>
20 #include <linux/parser.h>
21 #include <net/9p/client.h>
22 #include <net/9p/transport.h>
23 #include <linux/list.h>
24 #include <linux/spinlock.h>
25 
26 #ifdef CONFIG_NET_9P_DEBUG
27 unsigned int p9_debug_level;	/* feature-rific global debug level  */
28 EXPORT_SYMBOL(p9_debug_level);
29 module_param_named(debug, p9_debug_level, uint, 0);
30 MODULE_PARM_DESC(debug, "9P debugging level");
31 
_p9_debug(enum p9_debug_flags level,const char * func,const char * fmt,...)32 void _p9_debug(enum p9_debug_flags level, const char *func,
33 	       const char *fmt, ...)
34 {
35 	struct va_format vaf;
36 	va_list args;
37 
38 	if ((p9_debug_level & level) != level)
39 		return;
40 
41 	va_start(args, fmt);
42 
43 	vaf.fmt = fmt;
44 	vaf.va = &args;
45 
46 	if (level == P9_DEBUG_9P)
47 		pr_notice("(%8.8d) %pV", task_pid_nr(current), &vaf);
48 	else
49 		pr_notice("-- %s (%d): %pV", func, task_pid_nr(current), &vaf);
50 
51 	va_end(args);
52 }
53 EXPORT_SYMBOL(_p9_debug);
54 #endif
55 
56 /* Dynamic Transport Registration Routines */
57 
58 static DEFINE_SPINLOCK(v9fs_trans_lock);
59 static LIST_HEAD(v9fs_trans_list);
60 
61 /**
62  * v9fs_register_trans - register a new transport with 9p
63  * @m: structure describing the transport module and entry points
64  *
65  */
v9fs_register_trans(struct p9_trans_module * m)66 void v9fs_register_trans(struct p9_trans_module *m)
67 {
68 	spin_lock(&v9fs_trans_lock);
69 	list_add_tail(&m->list, &v9fs_trans_list);
70 	spin_unlock(&v9fs_trans_lock);
71 }
72 EXPORT_SYMBOL(v9fs_register_trans);
73 
74 /**
75  * v9fs_unregister_trans - unregister a 9p transport
76  * @m: the transport to remove
77  *
78  */
v9fs_unregister_trans(struct p9_trans_module * m)79 void v9fs_unregister_trans(struct p9_trans_module *m)
80 {
81 	spin_lock(&v9fs_trans_lock);
82 	list_del_init(&m->list);
83 	spin_unlock(&v9fs_trans_lock);
84 }
85 EXPORT_SYMBOL(v9fs_unregister_trans);
86 
87 /**
88  * v9fs_get_trans_by_name - get transport with the matching name
89  * @s: string identifying transport
90  *
91  */
v9fs_get_trans_by_name(char * s)92 struct p9_trans_module *v9fs_get_trans_by_name(char *s)
93 {
94 	struct p9_trans_module *t, *found = NULL;
95 
96 	spin_lock(&v9fs_trans_lock);
97 
98 	list_for_each_entry(t, &v9fs_trans_list, list)
99 		if (strcmp(t->name, s) == 0 &&
100 		    try_module_get(t->owner)) {
101 			found = t;
102 			break;
103 		}
104 
105 	spin_unlock(&v9fs_trans_lock);
106 	return found;
107 }
108 EXPORT_SYMBOL(v9fs_get_trans_by_name);
109 
110 /**
111  * v9fs_get_default_trans - get the default transport
112  *
113  */
114 
v9fs_get_default_trans(void)115 struct p9_trans_module *v9fs_get_default_trans(void)
116 {
117 	struct p9_trans_module *t, *found = NULL;
118 
119 	spin_lock(&v9fs_trans_lock);
120 
121 	list_for_each_entry(t, &v9fs_trans_list, list)
122 		if (t->def && try_module_get(t->owner)) {
123 			found = t;
124 			break;
125 		}
126 
127 	if (!found)
128 		list_for_each_entry(t, &v9fs_trans_list, list)
129 			if (try_module_get(t->owner)) {
130 				found = t;
131 				break;
132 			}
133 
134 	spin_unlock(&v9fs_trans_lock);
135 	return found;
136 }
137 EXPORT_SYMBOL(v9fs_get_default_trans);
138 
139 /**
140  * v9fs_put_trans - put trans
141  * @m: transport to put
142  *
143  */
v9fs_put_trans(struct p9_trans_module * m)144 void v9fs_put_trans(struct p9_trans_module *m)
145 {
146 	if (m)
147 		module_put(m->owner);
148 }
149 
150 /**
151  * init_p9 - Initialize module
152  *
153  */
init_p9(void)154 static int __init init_p9(void)
155 {
156 	int ret;
157 
158 	ret = p9_client_init();
159 	if (ret)
160 		return ret;
161 
162 	p9_error_init();
163 	pr_info("Installing 9P2000 support\n");
164 	p9_trans_fd_init();
165 
166 	return ret;
167 }
168 
169 /**
170  * exit_p9 - shutdown module
171  *
172  */
173 
exit_p9(void)174 static void __exit exit_p9(void)
175 {
176 	pr_info("Unloading 9P2000 support\n");
177 
178 	p9_trans_fd_exit();
179 	p9_client_exit();
180 }
181 
182 module_init(init_p9)
183 module_exit(exit_p9)
184 
185 MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
186 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
187 MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
188 MODULE_LICENSE("GPL");
189 MODULE_IMPORT_NS(VFS_internal_I_am_really_a_filesystem_and_am_NOT_a_driver);
190 MODULE_DESCRIPTION("Plan 9 Resource Sharing Support (9P2000)");
191