net/tipc/user_reg.c

   1 /*
   2  * net/tipc/user_reg.c: TIPC user registry code
   3  *
   4  * Copyright (c) 2000-2006, Ericsson AB
   5  * Copyright (c) 2004-2005, Wind River Systems
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the names of the copyright holders nor the names of its
  17  *    contributors may be used to endorse or promote products derived from
  18  *    this software without specific prior written permission.
  19  *
  20  * Alternatively, this software may be distributed under the terms of the
  21  * GNU General Public License ("GPL") version 2 as published by the Free
  22  * Software Foundation.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34  * POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "core.h"
  38 #include "user_reg.h"
  39
  40 /*
  41  * TIPC user registry keeps track of users of the tipc_port interface.
  42  *
  43  * The registry utilizes an array of "TIPC user" entries;
  44  * a user's ID is the index of their associated array entry.
  45  * Array entry 0 is not used, so userid 0 is not valid;
  46  * TIPC sometimes uses this value to denote an anonymous user.
  47  * The list of free entries is initially chained from last entry to entry 1.
  48  */
  49
  50 /**
  51  * struct tipc_user - registered TIPC user info
  52  * @next: index of next free registry entry (or -1 for an allocated entry)
  53  * @callback: ptr to routine to call when TIPC mode changes (NULL if none)
  54  * @usr_handle: user-defined value passed to callback routine
  55  * @ports: list of user ports owned by the user
  56  */
  57
  58 struct tipc_user {
  59         int next;
  60         tipc_mode_event callback;
  61         void *usr_handle;
  62         struct list_head ports;
  63 };
  64
  65 #define MAX_USERID 64
  66 #define USER_LIST_SIZE ((MAX_USERID + 1) * sizeof(struct tipc_user))
  67
  68 static struct tipc_user *users = NULL;
  69 static u32 next_free_user = MAX_USERID + 1;
  70 static DEFINE_SPINLOCK(reg_lock);
  71
  72 /**
  73  * reg_init - create TIPC user registry (but don't activate it)
  74  *
  75  * If registry has been pre-initialized it is left "as is".
  76  * NOTE: This routine may be called when TIPC is inactive.
  77  */
  78
  79 static int reg_init(void)
  80 {
  81         u32 i;
  82
  83         spin_lock_bh(&reg_lock);
  84         if (!users) {
  85                 users = kzalloc(USER_LIST_SIZE, GFP_ATOMIC);
  86                 if (users) {
  87                         for (i = 1; i <= MAX_USERID; i++) {
  88                                 users[i].next = i - 1;
  89                         }
  90                         next_free_user = MAX_USERID;
  91                 }
  92         }
  93         spin_unlock_bh(&reg_lock);
  94         return users ? 0 : -ENOMEM;
  95 }
  96
  97 /**
  98  * reg_callback - inform TIPC user about current operating mode
  99  */
 100
 101 static void reg_callback(struct tipc_user *user_ptr)
 102 {
 103         tipc_mode_event cb;
 104         void *arg;
 105
 106         spin_lock_bh(&reg_lock);
 107         cb = user_ptr->callback;
 108         arg = user_ptr->usr_handle;
 109         spin_unlock_bh(&reg_lock);
 110
 111         if (cb)
 112                 cb(arg, tipc_mode, tipc_own_addr);
 113 }
 114
 115 /**
 116  * tipc_reg_start - activate TIPC user registry
 117  */
 118
 119 int tipc_reg_start(void)
 120 {
 121         u32 u;
 122         int res;
 123
 124         if ((res = reg_init()))
 125                 return res;
 126
 127         for (u = 1; u <= MAX_USERID; u++) {
 128                 if (users[u].callback)
 129                         tipc_k_signal((Handler)reg_callback,
 130                                       (unsigned long)&users[u]);
 131         }
 132         return 0;
 133 }
 134
 135 /**
 136  * tipc_reg_stop - shut down & delete TIPC user registry
 137  */
 138
 139 void tipc_reg_stop(void)
 140 {
 141         int id;
 142
 143         if (!users)
 144                 return;
 145
 146         for (id = 1; id <= MAX_USERID; id++) {
 147                 if (users[id].callback)
 148                         reg_callback(&users[id]);
 149         }
 150         kfree(users);
 151         users = NULL;
 152 }
 153
 154 /**
 155  * tipc_attach - register a TIPC user
 156  *
 157  * NOTE: This routine may be called when TIPC is inactive.
 158  */
 159
 160 int tipc_attach(u32 *userid, tipc_mode_event cb, void *usr_handle)
 161 {
 162         struct tipc_user *user_ptr;
 163
 164         if ((tipc_mode == TIPC_NOT_RUNNING) && !cb)
 165                 return -ENOPROTOOPT;
 166         if (!users)
 167                 reg_init();
 168
 169         spin_lock_bh(&reg_lock);
 170         if (!next_free_user) {
 171                 spin_unlock_bh(&reg_lock);
 172                 return -EBUSY;
 173         }
 174         user_ptr = &users[next_free_user];
 175         *userid = next_free_user;
 176         next_free_user = user_ptr->next;
 177         user_ptr->next = -1;
 178         spin_unlock_bh(&reg_lock);
 179
 180         user_ptr->callback = cb;
 181         user_ptr->usr_handle = usr_handle;
 182         INIT_LIST_HEAD(&user_ptr->ports);
 183         atomic_inc(&tipc_user_count);
 184
 185         if (cb && (tipc_mode != TIPC_NOT_RUNNING))
 186                 tipc_k_signal((Handler)reg_callback, (unsigned long)user_ptr);
 187         return 0;
 188 }
 189
 190 /**
 191  * tipc_detach - deregister a TIPC user
 192  */
 193
 194 void tipc_detach(u32 userid)
 195 {
 196         struct tipc_user *user_ptr;
 197         struct list_head ports_temp;
 198         struct user_port *up_ptr, *temp_up_ptr;
 199
 200         if ((userid == 0) || (userid > MAX_USERID))
 201                 return;
 202
 203         spin_lock_bh(&reg_lock);
 204         if ((!users) || (users[userid].next >= 0)) {
 205                 spin_unlock_bh(&reg_lock);
 206                 return;
 207         }
 208
 209         user_ptr = &users[userid];
 210         user_ptr->callback = NULL;
 211         INIT_LIST_HEAD(&ports_temp);
 212         list_splice(&user_ptr->ports, &ports_temp);
 213         user_ptr->next = next_free_user;
 214         next_free_user = userid;
 215         spin_unlock_bh(&reg_lock);
 216
 217         atomic_dec(&tipc_user_count);
 218
 219         list_for_each_entry_safe(up_ptr, temp_up_ptr, &ports_temp, uport_list) {
 220                 tipc_deleteport(up_ptr->ref);
 221         }
 222 }
 223
 224 /**
 225  * tipc_reg_add_port - register a user's driver port
 226  */
 227
 228 int tipc_reg_add_port(struct user_port *up_ptr)
 229 {
 230         struct tipc_user *user_ptr;
 231
 232         if (up_ptr->user_ref == 0)
 233                 return 0;
 234         if (up_ptr->user_ref > MAX_USERID)
 235                 return -EINVAL;
 236         if ((tipc_mode == TIPC_NOT_RUNNING) || !users )
 237                 return -ENOPROTOOPT;
 238
 239         spin_lock_bh(&reg_lock);
 240         user_ptr = &users[up_ptr->user_ref];
 241         list_add(&up_ptr->uport_list, &user_ptr->ports);
 242         spin_unlock_bh(&reg_lock);
 243         return 0;
 244 }
 245
 246 /**
 247  * tipc_reg_remove_port - deregister a user's driver port
 248  */
 249
 250 int tipc_reg_remove_port(struct user_port *up_ptr)
 251 {
 252         if (up_ptr->user_ref == 0)
 253                 return 0;
 254         if (up_ptr->user_ref > MAX_USERID)
 255                 return -EINVAL;
 256         if (!users )
 257                 return -ENOPROTOOPT;
 258
 259         spin_lock_bh(&reg_lock);
 260         list_del_init(&up_ptr->uport_list);
 261         spin_unlock_bh(&reg_lock);
 262         return 0;
 263 }
 264