net/9p/mod.c

   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
  26 unsigned int p9_debug_level;    /* feature-rific global debug level  */
  27 EXPORT_SYMBOL(p9_debug_level);
  28 module_param_named(debug, p9_debug_level, uint, 0);
  29 MODULE_PARM_DESC(debug, "9P debugging level");
  30
  31 void _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 }
  52 EXPORT_SYMBOL(_p9_debug);
  53 #endif
  54
  55 /* Dynamic Transport Registration Routines */
  56
  57 static DEFINE_SPINLOCK(v9fs_trans_lock);
  58 static 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  */
  65 void 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 }
  71 EXPORT_SYMBOL(v9fs_register_trans);
  72
  73 /**
  74  * v9fs_unregister_trans - unregister a 9p transport
  75  * @m: the transport to remove
  76  *
  77  */
  78 void 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 }
  84 EXPORT_SYMBOL(v9fs_unregister_trans);
  85
  86 static 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  */
 109 struct 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 }
 124 EXPORT_SYMBOL(v9fs_get_trans_by_name);
 125
 126 static 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
 135 struct 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 }
 162 EXPORT_SYMBOL(v9fs_get_default_trans);
 163
 164 /**
 165  * v9fs_put_trans - put trans
 166  * @m: transport to put
 167  *
 168  */
 169 void 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  */
 179 static 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
 198 static void __exit exit_p9(void)
 199 {
 200         pr_info("Unloading 9P2000 support\n");
 201
 202         p9_client_exit();
 203 }
 204
 205 module_init(init_p9)
 206 module_exit(exit_p9)
 207
 208 MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
 209 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
 210 MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
 211 MODULE_LICENSE("GPL");
 212 MODULE_DESCRIPTION("Plan 9 Resource Sharing Support (9P2000)");