1 /* $NetBSD: dm_table.c,v 1.2 2008/12/19 15:24:03 haad Exp $ */ 2 3 /* 4 * Copyright (c) 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Adam Hamsik. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/types.h> 33 #include <sys/param.h> 34 35 #include <sys/kmem.h> 36 37 #include "dm.h" 38 39 /* 40 * There are two types of users of this interface: 41 * 42 * a) Readers such as 43 * dmstrategy, dmgetdisklabel, dmsize, dm_dev_status_ioctl, 44 * dm_table_deps_ioctl, dm_table_status_ioctl, dm_table_reload_ioctl 45 * 46 * b) Writers such as 47 * dm_dev_remove_ioctl, dm_dev_resume_ioctl, dm_table_clear_ioctl 48 * 49 * Writers can work with table_head only when there are no readers. I 50 * use reference counting on io_cnt. 51 * 52 */ 53 54 static int dm_table_busy(dm_table_head_t *, uint8_t ); 55 static void dm_table_unbusy(dm_table_head_t *); 56 57 /* 58 * Function to increment table user reference counter. Return id 59 * of table_id table. 60 * DM_TABLE_ACTIVE will return active table id. 61 * DM_TABLE_INACTIVE will return inactive table id. 62 */ 63 static int 64 dm_table_busy(dm_table_head_t *head, uint8_t table_id) 65 { 66 uint8_t id; 67 68 id = 0; 69 70 mutex_enter(&head->table_mtx); 71 72 if (table_id == DM_TABLE_ACTIVE) 73 id = head->cur_active_table; 74 else 75 id = 1 - head->cur_active_table; 76 77 head->io_cnt++; 78 79 mutex_exit(&head->table_mtx); 80 return id; 81 } 82 83 /* 84 * Function release table lock and eventually wakeup all waiters. 85 */ 86 static void 87 dm_table_unbusy(dm_table_head_t *head) 88 { 89 KASSERT(head->io_cnt != 0); 90 91 mutex_enter(&head->table_mtx); 92 93 if (--head->io_cnt == 0) 94 cv_broadcast(&head->table_cv); 95 96 mutex_exit(&head->table_mtx); 97 } 98 99 /* 100 * Return current active table to caller, increment io_cnt reference counter. 101 */ 102 dm_table_t * 103 dm_table_get_entry(dm_table_head_t *head, uint8_t table_id) 104 { 105 uint8_t id; 106 107 id = dm_table_busy(head, table_id); 108 109 return &head->tables[id]; 110 } 111 112 /* 113 * Decrement io reference counter and wake up all callers, with table_head cv. 114 */ 115 void 116 dm_table_release(dm_table_head_t *head, uint8_t table_id) 117 { 118 dm_table_unbusy(head); 119 } 120 121 /* 122 * Switch table from inactive to active mode. Have to wait until io_cnt is 0. 123 */ 124 void 125 dm_table_switch_tables(dm_table_head_t *head) 126 { 127 mutex_enter(&head->table_mtx); 128 129 while (head->io_cnt != 0) 130 cv_wait(&head->table_cv, &head->table_mtx); 131 132 head->cur_active_table = 1 - head->cur_active_table; 133 134 mutex_exit(&head->table_mtx); 135 } 136 137 /* 138 * Destroy all table data. This function can run when there are no 139 * readers on table lists. 140 * 141 * XXX Is it ok to call kmem_free and potentialy VOP_CLOSE with held mutex ?xs 142 */ 143 int 144 dm_table_destroy(dm_table_head_t *head, uint8_t table_id) 145 { 146 dm_table_t *tbl; 147 dm_table_entry_t *table_en; 148 uint8_t id; 149 150 mutex_enter(&head->table_mtx); 151 152 printf("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt); 153 154 while (head->io_cnt != 0) 155 cv_wait(&head->table_cv, &head->table_mtx); 156 157 if (table_id == DM_TABLE_ACTIVE) 158 id = head->cur_active_table; 159 else 160 id = 1 - head->cur_active_table; 161 162 tbl = &head->tables[id]; 163 164 while (!SLIST_EMPTY(tbl)) { /* List Deletion. */ 165 table_en = SLIST_FIRST(tbl); 166 /* 167 * Remove target specific config data. After successfull 168 * call table_en->target_config must be set to NULL. 169 */ 170 table_en->target->destroy(table_en); 171 172 SLIST_REMOVE_HEAD(tbl, next); 173 174 kmem_free(table_en, sizeof(*table_en)); 175 } 176 177 mutex_exit(&head->table_mtx); 178 179 return 0; 180 } 181 182 /* 183 * Return length of active table in device. 184 */ 185 uint64_t 186 dm_table_size(dm_table_head_t *head) 187 { 188 dm_table_t *tbl; 189 dm_table_entry_t *table_en; 190 uint64_t length; 191 uint8_t id; 192 193 length = 0; 194 195 id = dm_table_busy(head, DM_TABLE_ACTIVE); 196 197 /* Select active table */ 198 tbl = &head->tables[id]; 199 200 /* 201 * Find out what tables I want to select. 202 * if length => rawblkno then we should used that table. 203 */ 204 SLIST_FOREACH(table_en, tbl, next) 205 length += table_en->length; 206 207 dm_table_unbusy(head); 208 209 return length / DEV_BSIZE; 210 } 211 212 /* 213 * Return > 0 if table is at least one table entry (returns number of entries) 214 * and return 0 if there is not. Target count returned from this function 215 * doesn't need to be true when userspace user receive it (after return 216 * there can be dm_dev_resume_ioctl), therfore this isonly informative. 217 */ 218 int 219 dm_table_get_target_count(dm_table_head_t *head, uint8_t table_id) 220 { 221 dm_table_entry_t *table_en; 222 dm_table_t *tbl; 223 uint32_t target_count; 224 uint8_t id; 225 226 target_count = 0; 227 228 id = dm_table_busy(head, table_id); 229 230 tbl = &head->tables[id]; 231 232 SLIST_FOREACH(table_en, tbl, next) 233 target_count++; 234 235 dm_table_unbusy(head); 236 237 return target_count; 238 } 239 240 241 /* 242 * Initialize table_head structures, I'm trying to keep this structure as 243 * opaque as possible. 244 */ 245 void 246 dm_table_head_init(dm_table_head_t *head) 247 { 248 head->cur_active_table = 0; 249 head->io_cnt = 0; 250 251 /* Initialize tables. */ 252 SLIST_INIT(&head->tables[0]); 253 SLIST_INIT(&head->tables[1]); 254 255 mutex_init(&head->table_mtx, MUTEX_DEFAULT, IPL_NONE); 256 cv_init(&head->table_cv, "dm_io"); 257 } 258 259 /* 260 * Destroy all variables in table_head 261 */ 262 void 263 dm_table_head_destroy(dm_table_head_t *head) 264 { 265 KASSERT(!mutex_owned(&head->table_mtx)); 266 KASSERT(!cv_has_waiters(&head->table_cv)); 267 /* tables doens't exists when I call this routine, therefore 268 it doesn't make sense to have io_cnt != 0 */ 269 KASSERT(head->io_cnt == 0); 270 271 cv_destroy(&head->table_cv); 272 mutex_destroy(&head->table_mtx); 273 } 274