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 = 0;
  69 static u32 next_free_user = MAX_USERID + 1;
  70 static spinlock_t reg_lock = SPIN_LOCK_UNLOCKED;
  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 = (struct tipc_user *)kmalloc(USER_LIST_SIZE, GFP_ATOMIC);
  86                 if (users) {
  87                         memset(users, 0, USER_LIST_SIZE);
  88                         for (i = 1; i <= MAX_USERID; i++) {
  89                                 users[i].next = i - 1;
  90                         }
  91                         next_free_user = MAX_USERID;
  92                 }
  93         }
  94         spin_unlock_bh(&reg_lock);
  95         return users ? TIPC_OK : -ENOMEM;
  96 }
  97
  98 /**
  99  * reg_callback - inform TIPC user about current operating mode
 100  */
 101
 102 static void reg_callback(struct tipc_user *user_ptr)
 103 {
 104         tipc_mode_event cb;
 105         void *arg;
 106
 107         spin_lock_bh(&reg_lock);
 108         cb = user_ptr->callback;
 109         arg = user_ptr->usr_handle;
 110         spin_unlock_bh(&reg_lock);
 111
 112         if (cb)
 113                 cb(arg, tipc_mode, tipc_own_addr);
 114 }
 115
 116 /**
 117  * tipc_reg_start - activate TIPC user registry
 118  */
 119
 120 int tipc_reg_start(void)
 121 {
 122         u32 u;
 123         int res;
 124
 125         if ((res = reg_init()))
 126                 return res;
 127
 128         for (u = 1; u <= MAX_USERID; u++) {
 129                 if (users[u].callback)
 130                         tipc_k_signal((Handler)reg_callback,
 131                                       (unsigned long)&users[u]);
 132         }
 133         return TIPC_OK;
 134 }
 135
 136 /**
 137  * tipc_reg_stop - shut down & delete TIPC user registry
 138  */
 139
 140 void tipc_reg_stop(void)
 141 {
 142         int id;
 143
 144         if (!users)
 145                 return;
 146
 147         for (id = 1; id <= MAX_USERID; id++) {
 148                 if (users[id].callback)
 149                         reg_callback(&users[id]);
 150         }
 151         kfree(users);
 152         users = 0;
 153 }
 154
 155 /**
 156  * tipc_attach - register a TIPC user
 157  *
 158  * NOTE: This routine may be called when TIPC is inactive.
 159  */
 160
 161 int tipc_attach(u32 *userid, tipc_mode_event cb, void *usr_handle)
 162 {
 163         struct tipc_user *user_ptr;
 164
 165         if ((tipc_mode == TIPC_NOT_RUNNING) && !cb)
 166                 return -ENOPROTOOPT;
 167         if (!users)
 168                 reg_init();
 169
 170         spin_lock_bh(&reg_lock);
 171         if (!next_free_user) {
 172                 spin_unlock_bh(&reg_lock);
 173                 return -EBUSY;
 174         }
 175         user_ptr = &users[next_free_user];
 176         *userid = next_free_user;
 177         next_free_user = user_ptr->next;
 178         user_ptr->next = -1;
 179         spin_unlock_bh(&reg_lock);
 180
 181         user_ptr->callback = cb;
 182         user_ptr->usr_handle = usr_handle;
 183         INIT_LIST_HEAD(&user_ptr->ports);
 184         atomic_inc(&tipc_user_count);
 185
 186         if (cb && (tipc_mode != TIPC_NOT_RUNNING))
 187                 tipc_k_signal((Handler)reg_callback, (unsigned long)user_ptr);
 188         return TIPC_OK;
 189 }
 190
 191 /**
 192  * tipc_detach - deregister a TIPC user
 193  */
 194
 195 void tipc_detach(u32 userid)
 196 {
 197         struct tipc_user *user_ptr;
 198         struct list_head ports_temp;
 199         struct user_port *up_ptr, *temp_up_ptr;
 200
 201         if ((userid == 0) || (userid > MAX_USERID))
 202                 return;
 203
 204         spin_lock_bh(&reg_lock);
 205         if ((!users) || (users[userid].next >= 0)) {
 206                 spin_unlock_bh(&reg_lock);
 207                 return;
 208         }
 209
 210         user_ptr = &users[userid];
 211         user_ptr->callback = NULL;
 212         INIT_LIST_HEAD(&ports_temp);
 213         list_splice(&user_ptr->ports, &ports_temp);
 214         user_ptr->next = next_free_user;
 215         next_free_user = userid;
 216         spin_unlock_bh(&reg_lock);
 217
 218         atomic_dec(&tipc_user_count);
 219
 220         list_for_each_entry_safe(up_ptr, temp_up_ptr, &ports_temp, uport_list) {
 221                 tipc_deleteport(up_ptr->ref);
 222         }
 223 }
 224
 225 /**
 226  * tipc_reg_add_port - register a user's driver port
 227  */
 228
 229 int tipc_reg_add_port(struct user_port *up_ptr)
 230 {
 231         struct tipc_user *user_ptr;
 232
 233         if (up_ptr->user_ref == 0)
 234                 return TIPC_OK;
 235         if (up_ptr->user_ref > MAX_USERID)
 236                 return -EINVAL;
 237         if ((tipc_mode == TIPC_NOT_RUNNING) || !users )
 238                 return -ENOPROTOOPT;
 239
 240         spin_lock_bh(&reg_lock);
 241         user_ptr = &users[up_ptr->user_ref];
 242         list_add(&up_ptr->uport_list, &user_ptr->ports);
 243         spin_unlock_bh(&reg_lock);
 244         return TIPC_OK;
 245 }
 246
 247 /**
 248  * tipc_reg_remove_port - deregister a user's driver port
 249  */
 250
 251 int tipc_reg_remove_port(struct user_port *up_ptr)
 252 {
 253         if (up_ptr->user_ref == 0)
 254                 return TIPC_OK;
 255         if (up_ptr->user_ref > MAX_USERID)
 256                 return -EINVAL;
 257         if (!users )
 258                 return -ENOPROTOOPT;
 259
 260         spin_lock_bh(&reg_lock);
 261         list_del_init(&up_ptr->uport_list);
 262         spin_unlock_bh(&reg_lock);
 263         return TIPC_OK;
 264 }
 265