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/malloc.h> 36 37 #include <dev/disk/dm/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. We 50 * simply use shared/exclusive locking to ensure this. 51 */ 52 53 static int dm_table_busy(dm_table_head_t *, uint8_t); 54 static void dm_table_unbusy(dm_table_head_t *); 55 56 /* 57 * Function to increment table user reference counter. Return id 58 * of table_id table. 59 * DM_TABLE_ACTIVE will return active table id. 60 * DM_TABLE_INACTIVE will return inactive table id. 61 */ 62 static int 63 dm_table_busy(dm_table_head_t * head, uint8_t table_id) 64 { 65 uint8_t id; 66 67 id = 0; 68 69 lockmgr(&head->table_mtx, LK_SHARED); 70 71 if (table_id == DM_TABLE_ACTIVE) 72 id = head->cur_active_table; 73 else 74 id = 1 - head->cur_active_table; 75 76 atomic_add_int(&head->io_cnt, 1); 77 78 return id; 79 } 80 /* 81 * Function release table lock and eventually wakeup all waiters. 82 */ 83 static void 84 dm_table_unbusy(dm_table_head_t * head) 85 { 86 KKASSERT(head->io_cnt != 0); 87 88 atomic_subtract_int(&head->io_cnt, 1); 89 90 lockmgr(&head->table_mtx, LK_RELEASE); 91 } 92 /* 93 * Return current active table to caller, increment io_cnt reference counter. 94 */ 95 dm_table_t * 96 dm_table_get_entry(dm_table_head_t * head, uint8_t table_id) 97 { 98 uint8_t id; 99 100 id = dm_table_busy(head, table_id); 101 102 return &head->tables[id]; 103 } 104 /* 105 * Decrement io reference counter and release shared lock. 106 */ 107 void 108 dm_table_release(dm_table_head_t * head, uint8_t table_id) 109 { 110 dm_table_unbusy(head); 111 } 112 /* 113 * Switch table from inactive to active mode. Have to wait until io_cnt is 0. 114 */ 115 void 116 dm_table_switch_tables(dm_table_head_t * head) 117 { 118 lockmgr(&head->table_mtx, LK_EXCLUSIVE); 119 120 head->cur_active_table = 1 - head->cur_active_table; 121 122 lockmgr(&head->table_mtx, LK_RELEASE); 123 } 124 /* 125 * Destroy all table data. This function can run when there are no 126 * readers on table lists. 127 */ 128 int 129 dm_table_destroy(dm_table_head_t * head, uint8_t table_id) 130 { 131 dm_table_t *tbl; 132 dm_table_entry_t *table_en; 133 uint8_t id; 134 135 lockmgr(&head->table_mtx, LK_EXCLUSIVE); 136 137 aprint_debug("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt); 138 139 if (table_id == DM_TABLE_ACTIVE) 140 id = head->cur_active_table; 141 else 142 id = 1 - head->cur_active_table; 143 144 tbl = &head->tables[id]; 145 146 while (!SLIST_EMPTY(tbl)) { /* List Deletion. */ 147 table_en = SLIST_FIRST(tbl); 148 /* 149 * Remove target specific config data. After successfull 150 * call table_en->target_config must be set to NULL. 151 */ 152 table_en->target->destroy(table_en); 153 154 SLIST_REMOVE_HEAD(tbl, next); 155 156 kfree(table_en, M_DM); 157 } 158 159 lockmgr(&head->table_mtx, LK_RELEASE); 160 161 return 0; 162 } 163 /* 164 * Return length of active table in device. 165 */ 166 uint64_t 167 dm_table_size(dm_table_head_t * head) 168 { 169 dm_table_t *tbl; 170 dm_table_entry_t *table_en; 171 uint64_t length; 172 uint8_t id; 173 174 length = 0; 175 176 id = dm_table_busy(head, DM_TABLE_ACTIVE); 177 178 /* Select active table */ 179 tbl = &head->tables[id]; 180 181 /* 182 * Find out what tables I want to select. 183 * if length => rawblkno then we should used that table. 184 */ 185 SLIST_FOREACH(table_en, tbl, next) { 186 length += table_en->length; 187 } 188 189 dm_table_unbusy(head); 190 191 return length; 192 } 193 /* 194 * Return > 0 if table is at least one table entry (returns number of entries) 195 * and return 0 if there is not. Target count returned from this function 196 * doesn't need to be true when userspace user receive it (after return 197 * there can be dm_dev_resume_ioctl), therfore this isonly informative. 198 */ 199 int 200 dm_table_get_target_count(dm_table_head_t * head, uint8_t table_id) 201 { 202 dm_table_entry_t *table_en; 203 dm_table_t *tbl; 204 uint32_t target_count; 205 uint8_t id; 206 207 target_count = 0; 208 209 id = dm_table_busy(head, table_id); 210 211 tbl = &head->tables[id]; 212 213 SLIST_FOREACH(table_en, tbl, next) 214 target_count++; 215 216 dm_table_unbusy(head); 217 218 return target_count; 219 } 220 221 222 /* 223 * Initialize table_head structures, I'm trying to keep this structure as 224 * opaque as possible. 225 */ 226 void 227 dm_table_head_init(dm_table_head_t * head) 228 { 229 head->cur_active_table = 0; 230 head->io_cnt = 0; 231 232 /* Initialize tables. */ 233 SLIST_INIT(&head->tables[0]); 234 SLIST_INIT(&head->tables[1]); 235 236 lockinit(&head->table_mtx, "dmtbl", 0, LK_CANRECURSE); 237 } 238 /* 239 * Destroy all variables in table_head 240 */ 241 void 242 dm_table_head_destroy(dm_table_head_t * head) 243 { 244 KKASSERT(lockcount(&head->table_mtx) == 0); 245 246 /* tables doens't exists when I call this routine, therefore it 247 * doesn't make sense to have io_cnt != 0 */ 248 KKASSERT(head->io_cnt == 0); 249 250 lockuninit(&head->table_mtx); 251 } 252