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  * @ports: list of user ports owned by the user
  54  */
  55
  56 struct tipc_user {
  57         int next;
  58         struct list_head ports;
  59 };
  60
  61 #define MAX_USERID 64
  62 #define USER_LIST_SIZE ((MAX_USERID + 1) * sizeof(struct tipc_user))
  63
  64 static struct tipc_user *users = NULL;
  65 static u32 next_free_user = MAX_USERID + 1;
  66 static DEFINE_SPINLOCK(reg_lock);
  67
  68 /**
  69  * reg_init - create TIPC user registry (but don't activate it)
  70  *
  71  * If registry has been pre-initialized it is left "as is".
  72  * NOTE: This routine may be called when TIPC is inactive.
  73  */
  74
  75 static int reg_init(void)
  76 {
  77         u32 i;
  78
  79         spin_lock_bh(&reg_lock);
  80         if (!users) {
  81                 users = kzalloc(USER_LIST_SIZE, GFP_ATOMIC);
  82                 if (users) {
  83                         for (i = 1; i <= MAX_USERID; i++) {
  84                                 users[i].next = i - 1;
  85                         }
  86                         next_free_user = MAX_USERID;
  87                 }
  88         }
  89         spin_unlock_bh(&reg_lock);
  90         return users ? 0 : -ENOMEM;
  91 }
  92
  93 /**
  94  * tipc_reg_start - activate TIPC user registry
  95  */
  96
  97 int tipc_reg_start(void)
  98 {
  99         return reg_init();
 100 }
 101
 102 /**
 103  * tipc_reg_stop - shut down & delete TIPC user registry
 104  */
 105
 106 void tipc_reg_stop(void)
 107 {
 108         if (!users)
 109                 return;
 110
 111         kfree(users);
 112         users = NULL;
 113 }
 114
 115 /**
 116  * tipc_attach - register a TIPC user
 117  *
 118  * NOTE: This routine may be called when TIPC is inactive.
 119  */
 120
 121 int tipc_attach(u32 *userid)
 122 {
 123         struct tipc_user *user_ptr;
 124
 125         if (!users)
 126                 reg_init();
 127
 128         spin_lock_bh(&reg_lock);
 129         if (!next_free_user) {
 130                 spin_unlock_bh(&reg_lock);
 131                 return -EBUSY;
 132         }
 133         user_ptr = &users[next_free_user];
 134         *userid = next_free_user;
 135         next_free_user = user_ptr->next;
 136         user_ptr->next = -1;
 137         spin_unlock_bh(&reg_lock);
 138
 139         INIT_LIST_HEAD(&user_ptr->ports);
 140         atomic_inc(&tipc_user_count);
 141
 142         return 0;
 143 }
 144
 145 /**
 146  * tipc_detach - deregister a TIPC user
 147  */
 148
 149 void tipc_detach(u32 userid)
 150 {
 151         struct tipc_user *user_ptr;
 152         struct list_head ports_temp;
 153         struct user_port *up_ptr, *temp_up_ptr;
 154
 155         if ((userid == 0) || (userid > MAX_USERID))
 156                 return;
 157
 158         spin_lock_bh(&reg_lock);
 159         if ((!users) || (users[userid].next >= 0)) {
 160                 spin_unlock_bh(&reg_lock);
 161                 return;
 162         }
 163
 164         user_ptr = &users[userid];
 165         INIT_LIST_HEAD(&ports_temp);
 166         list_splice(&user_ptr->ports, &ports_temp);
 167         user_ptr->next = next_free_user;
 168         next_free_user = userid;
 169         spin_unlock_bh(&reg_lock);
 170
 171         atomic_dec(&tipc_user_count);
 172
 173         list_for_each_entry_safe(up_ptr, temp_up_ptr, &ports_temp, uport_list) {
 174                 tipc_deleteport(up_ptr->ref);
 175         }
 176 }
 177
 178 /**
 179  * tipc_reg_add_port - register a user's driver port
 180  */
 181
 182 int tipc_reg_add_port(struct user_port *up_ptr)
 183 {
 184         struct tipc_user *user_ptr;
 185
 186         if (up_ptr->user_ref == 0)
 187                 return 0;
 188         if (up_ptr->user_ref > MAX_USERID)
 189                 return -EINVAL;
 190         if ((tipc_mode == TIPC_NOT_RUNNING) || !users )
 191                 return -ENOPROTOOPT;
 192
 193         spin_lock_bh(&reg_lock);
 194         user_ptr = &users[up_ptr->user_ref];
 195         list_add(&up_ptr->uport_list, &user_ptr->ports);
 196         spin_unlock_bh(&reg_lock);
 197         return 0;
 198 }
 199
 200 /**
 201  * tipc_reg_remove_port - deregister a user's driver port
 202  */
 203
 204 int tipc_reg_remove_port(struct user_port *up_ptr)
 205 {
 206         if (up_ptr->user_ref == 0)
 207                 return 0;
 208         if (up_ptr->user_ref > MAX_USERID)
 209                 return -EINVAL;
 210         if (!users )
 211                 return -ENOPROTOOPT;
 212
 213         spin_lock_bh(&reg_lock);
 214         list_del_init(&up_ptr->uport_list);
 215         spin_unlock_bh(&reg_lock);
 216         return 0;
 217 }
 218