1 /* $NetBSD: dm_table.c,v 1.5 2010/01/04 00:19:08 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 * Function release table lock and eventually wakeup all waiters. 84 */ 85 static void 86 dm_table_unbusy(dm_table_head_t * head) 87 { 88 KASSERT(head->io_cnt != 0); 89 90 mutex_enter(&head->table_mtx); 91 92 if (--head->io_cnt == 0) 93 cv_broadcast(&head->table_cv); 94 95 mutex_exit(&head->table_mtx); 96 } 97 /* 98 * Return current active table to caller, increment io_cnt reference counter. 99 */ 100 dm_table_t * 101 dm_table_get_entry(dm_table_head_t * head, uint8_t table_id) 102 { 103 uint8_t id; 104 105 id = dm_table_busy(head, table_id); 106 107 return &head->tables[id]; 108 } 109 /* 110 * Decrement io reference counter and wake up all callers, with table_head cv. 111 */ 112 void 113 dm_table_release(dm_table_head_t * head, uint8_t table_id) 114 { 115 dm_table_unbusy(head); 116 } 117 /* 118 * Switch table from inactive to active mode. Have to wait until io_cnt is 0. 119 */ 120 void 121 dm_table_switch_tables(dm_table_head_t * head) 122 { 123 mutex_enter(&head->table_mtx); 124 125 while (head->io_cnt != 0) 126 cv_wait(&head->table_cv, &head->table_mtx); 127 128 head->cur_active_table = 1 - head->cur_active_table; 129 130 mutex_exit(&head->table_mtx); 131 } 132 /* 133 * Destroy all table data. This function can run when there are no 134 * readers on table lists. 135 * 136 * XXX Is it ok to call kmem_free and potentialy VOP_CLOSE with held mutex ?xs 137 */ 138 int 139 dm_table_destroy(dm_table_head_t * head, uint8_t table_id) 140 { 141 dm_table_t *tbl; 142 dm_table_entry_t *table_en; 143 uint8_t id; 144 145 mutex_enter(&head->table_mtx); 146 147 aprint_debug("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt); 148 149 while (head->io_cnt != 0) 150 cv_wait(&head->table_cv, &head->table_mtx); 151 152 if (table_id == DM_TABLE_ACTIVE) 153 id = head->cur_active_table; 154 else 155 id = 1 - head->cur_active_table; 156 157 tbl = &head->tables[id]; 158 159 while (!SLIST_EMPTY(tbl)) { /* List Deletion. */ 160 table_en = SLIST_FIRST(tbl); 161 /* 162 * Remove target specific config data. After successfull 163 * call table_en->target_config must be set to NULL. 164 */ 165 table_en->target->destroy(table_en); 166 167 SLIST_REMOVE_HEAD(tbl, next); 168 169 kmem_free(table_en, sizeof(*table_en)); 170 } 171 172 mutex_exit(&head->table_mtx); 173 174 return 0; 175 } 176 /* 177 * Return length of active table in device. 178 */ 179 uint64_t 180 dm_table_size(dm_table_head_t * head) 181 { 182 dm_table_t *tbl; 183 dm_table_entry_t *table_en; 184 uint64_t length; 185 uint8_t id; 186 187 length = 0; 188 189 id = dm_table_busy(head, DM_TABLE_ACTIVE); 190 191 /* Select active table */ 192 tbl = &head->tables[id]; 193 194 /* 195 * Find out what tables I want to select. 196 * if length => rawblkno then we should used that table. 197 */ 198 SLIST_FOREACH(table_en, tbl, next) 199 length += table_en->length; 200 201 dm_table_unbusy(head); 202 203 return length; 204 } 205 /* 206 * Return > 0 if table is at least one table entry (returns number of entries) 207 * and return 0 if there is not. Target count returned from this function 208 * doesn't need to be true when userspace user receive it (after return 209 * there can be dm_dev_resume_ioctl), therfore this isonly informative. 210 */ 211 int 212 dm_table_get_target_count(dm_table_head_t * head, uint8_t table_id) 213 { 214 dm_table_entry_t *table_en; 215 dm_table_t *tbl; 216 uint32_t target_count; 217 uint8_t id; 218 219 target_count = 0; 220 221 id = dm_table_busy(head, table_id); 222 223 tbl = &head->tables[id]; 224 225 SLIST_FOREACH(table_en, tbl, next) 226 target_count++; 227 228 dm_table_unbusy(head); 229 230 return target_count; 231 } 232 233 234 /* 235 * Initialize table_head structures, I'm trying to keep this structure as 236 * opaque as possible. 237 */ 238 void 239 dm_table_head_init(dm_table_head_t * head) 240 { 241 head->cur_active_table = 0; 242 head->io_cnt = 0; 243 244 /* Initialize tables. */ 245 SLIST_INIT(&head->tables[0]); 246 SLIST_INIT(&head->tables[1]); 247 248 mutex_init(&head->table_mtx, MUTEX_DEFAULT, IPL_NONE); 249 cv_init(&head->table_cv, "dm_io"); 250 } 251 /* 252 * Destroy all variables in table_head 253 */ 254 void 255 dm_table_head_destroy(dm_table_head_t * head) 256 { 257 KASSERT(!mutex_owned(&head->table_mtx)); 258 KASSERT(!cv_has_waiters(&head->table_cv)); 259 /* tables doens't exists when I call this routine, therefore it 260 * doesn't make sense to have io_cnt != 0 */ 261 KASSERT(head->io_cnt == 0); 262 263 cv_destroy(&head->table_cv); 264 mutex_destroy(&head->table_mtx); 265 } 266