1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *  9P entry point
4 *
5 *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
6 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
7 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/module.h>
13#include <linux/kmod.h>
14#include <linux/errno.h>
15#include <linux/sched.h>
16#include <linux/moduleparam.h>
17#include <net/9p/9p.h>
18#include <linux/fs.h>
19#include <linux/parser.h>
20#include <net/9p/client.h>
21#include <net/9p/transport.h>
22#include <linux/list.h>
23#include <linux/spinlock.h>
24
25#ifdef CONFIG_NET_9P_DEBUG
26unsigned int p9_debug_level;	/* feature-rific global debug level  */
27EXPORT_SYMBOL(p9_debug_level);
28module_param_named(debug, p9_debug_level, uint, 0);
29MODULE_PARM_DESC(debug, "9P debugging level");
30
31void _p9_debug(enum p9_debug_flags level, const char *func,
32	       const char *fmt, ...)
33{
34	struct va_format vaf;
35	va_list args;
36
37	if ((p9_debug_level & level) != level)
38		return;
39
40	va_start(args, fmt);
41
42	vaf.fmt = fmt;
43	vaf.va = &args;
44
45	if (level == P9_DEBUG_9P)
46		pr_notice("(%8.8d) %pV", task_pid_nr(current), &vaf);
47	else
48		pr_notice("-- %s (%d): %pV", func, task_pid_nr(current), &vaf);
49
50	va_end(args);
51}
52EXPORT_SYMBOL(_p9_debug);
53#endif
54
55/* Dynamic Transport Registration Routines */
56
57static DEFINE_SPINLOCK(v9fs_trans_lock);
58static LIST_HEAD(v9fs_trans_list);
59
60/**
61 * v9fs_register_trans - register a new transport with 9p
62 * @m: structure describing the transport module and entry points
63 *
64 */
65void v9fs_register_trans(struct p9_trans_module *m)
66{
67	spin_lock(&v9fs_trans_lock);
68	list_add_tail(&m->list, &v9fs_trans_list);
69	spin_unlock(&v9fs_trans_lock);
70}
71EXPORT_SYMBOL(v9fs_register_trans);
72
73/**
74 * v9fs_unregister_trans - unregister a 9p transport
75 * @m: the transport to remove
76 *
77 */
78void v9fs_unregister_trans(struct p9_trans_module *m)
79{
80	spin_lock(&v9fs_trans_lock);
81	list_del_init(&m->list);
82	spin_unlock(&v9fs_trans_lock);
83}
84EXPORT_SYMBOL(v9fs_unregister_trans);
85
86static struct p9_trans_module *_p9_get_trans_by_name(const char *s)
87{
88	struct p9_trans_module *t, *found = NULL;
89
90	spin_lock(&v9fs_trans_lock);
91
92	list_for_each_entry(t, &v9fs_trans_list, list)
93		if (strcmp(t->name, s) == 0 &&
94		    try_module_get(t->owner)) {
95			found = t;
96			break;
97		}
98
99	spin_unlock(&v9fs_trans_lock);
100
101	return found;
102}
103
104/**
105 * v9fs_get_trans_by_name - get transport with the matching name
106 * @s: string identifying transport
107 *
108 */
109struct p9_trans_module *v9fs_get_trans_by_name(const char *s)
110{
111	struct p9_trans_module *found = NULL;
112
113	found = _p9_get_trans_by_name(s);
114
115#ifdef CONFIG_MODULES
116	if (!found) {
117		request_module("9p-%s", s);
118		found = _p9_get_trans_by_name(s);
119	}
120#endif
121
122	return found;
123}
124EXPORT_SYMBOL(v9fs_get_trans_by_name);
125
126static const char * const v9fs_default_transports[] = {
127	"virtio", "tcp", "fd", "unix", "xen", "rdma",
128};
129
130/**
131 * v9fs_get_default_trans - get the default transport
132 *
133 */
134
135struct p9_trans_module *v9fs_get_default_trans(void)
136{
137	struct p9_trans_module *t, *found = NULL;
138	int i;
139
140	spin_lock(&v9fs_trans_lock);
141
142	list_for_each_entry(t, &v9fs_trans_list, list)
143		if (t->def && try_module_get(t->owner)) {
144			found = t;
145			break;
146		}
147
148	if (!found)
149		list_for_each_entry(t, &v9fs_trans_list, list)
150			if (try_module_get(t->owner)) {
151				found = t;
152				break;
153			}
154
155	spin_unlock(&v9fs_trans_lock);
156
157	for (i = 0; !found && i < ARRAY_SIZE(v9fs_default_transports); i++)
158		found = v9fs_get_trans_by_name(v9fs_default_transports[i]);
159
160	return found;
161}
162EXPORT_SYMBOL(v9fs_get_default_trans);
163
164/**
165 * v9fs_put_trans - put trans
166 * @m: transport to put
167 *
168 */
169void v9fs_put_trans(struct p9_trans_module *m)
170{
171	if (m)
172		module_put(m->owner);
173}
174
175/**
176 * init_p9 - Initialize module
177 *
178 */
179static int __init init_p9(void)
180{
181	int ret;
182
183	ret = p9_client_init();
184	if (ret)
185		return ret;
186
187	p9_error_init();
188	pr_info("Installing 9P2000 support\n");
189
190	return ret;
191}
192
193/**
194 * exit_p9 - shutdown module
195 *
196 */
197
198static void __exit exit_p9(void)
199{
200	pr_info("Unloading 9P2000 support\n");
201
202	p9_client_exit();
203}
204
205module_init(init_p9)
206module_exit(exit_p9)
207
208MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
209MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
210MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
211MODULE_LICENSE("GPL");
212MODULE_DESCRIPTION("Plan 9 Resource Sharing Support (9P2000)");
213