sys/dev/disk/dm/dm_target.c

   1 /*        $NetBSD: dm_target.c,v 1.12 2010/01/04 00:14:41 haad Exp $      */
   2
   3 /*
   4  * Copyright (c) 2010-2011 Alex Hornung <alex@alexhornung.com>
   5  * Copyright (c) 2008 The NetBSD Foundation, Inc.
   6  * All rights reserved.
   7  *
   8  * This code is derived from software contributed to The NetBSD Foundation
   9  * by Adam Hamsik.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code Must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  30  * POSSIBILITY OF SUCH DAMAGE.
  31  */
  32
  33 #include <sys/malloc.h>
  34 #include <sys/module.h>
  35 #include <sys/linker.h>
  36 #include <cpu/atomic.h>
  37 #include <dev/disk/dm/dm.h>
  38 #include <dev/disk/dm/netbsd-dm.h>
  39
  40 static dm_target_t *dm_target_lookup_name(const char *);
  41
  42 static TAILQ_HEAD(, dm_target) dm_target_list;
  43
  44 static struct lock dm_target_mutex;
  45
  46 void
  47 dm_target_busy(dm_target_t *target)
  48 {
  49         atomic_add_int(&target->ref_cnt, 1);
  50 }
  51
  52 /*
  53  * Release reference counter on target.
  54  */
  55 void
  56 dm_target_unbusy(dm_target_t *target)
  57 {
  58         KKASSERT(target->ref_cnt > 0);
  59         atomic_subtract_int(&target->ref_cnt, 1);
  60 }
  61
  62 /*
  63  * Try to autoload the module for the requested target.
  64  */
  65 dm_target_t *
  66 dm_target_autoload(const char *dm_target_name)
  67 {
  68         char mod_name[128];
  69         dm_target_t *dmt;
  70         linker_file_t linker_file;
  71         int error;
  72
  73         ksnprintf(mod_name, sizeof(mod_name), "dm_target_%s", dm_target_name);
  74         error = linker_reference_module(mod_name, NULL, &linker_file);
  75         if (error != 0) {
  76                 kprintf("dm: could not autoload module for target %s\n",
  77                     dm_target_name);
  78                 return NULL;
  79         }
  80
  81         dmt = dm_target_lookup(dm_target_name);
  82         if (dmt == NULL) {
  83                 linker_release_module(NULL, NULL, linker_file);
  84                 return NULL;
  85         }
  86
  87         /* XXX: extra-big hack to allow users to kldunload the module */
  88         linker_file->userrefs = 1;
  89
  90         return dmt;
  91 }
  92
  93 /*
  94  * Lookup for target in global target list.
  95  */
  96 dm_target_t *
  97 dm_target_lookup(const char *dm_target_name)
  98 {
  99         dm_target_t *dmt;
 100
 101         dmt = NULL;
 102
 103         if (dm_target_name == NULL)
 104                 return NULL;
 105
 106         lockmgr(&dm_target_mutex, LK_EXCLUSIVE);
 107
 108         dmt = dm_target_lookup_name(dm_target_name);
 109         if (dmt != NULL)
 110                 dm_target_busy(dmt);
 111
 112         lockmgr(&dm_target_mutex, LK_RELEASE);
 113
 114         return dmt;
 115 }
 116
 117 /*
 118  * Search for name in TAILQ and return apropriate pointer.
 119  */
 120 static dm_target_t *
 121 dm_target_lookup_name(const char *dm_target_name)
 122 {
 123         dm_target_t *dm_target;
 124
 125         TAILQ_FOREACH(dm_target, &dm_target_list, dm_target_next) {
 126                 if (strcmp(dm_target_name, dm_target->name) == 0)
 127                         return dm_target;
 128         }
 129
 130         return NULL;
 131 }
 132
 133 /*
 134  * Insert new target struct into the TAILQ.
 135  * dm_target contains name, version, function pointer to specific target
 136  * functions.
 137  */
 138 int
 139 dm_target_insert(dm_target_t *dm_target)
 140 {
 141         dm_target_t *dmt;
 142
 143         if (dm_target->strategy == NULL) {
 144                 kprintf("dm: %s missing strategy\n", dm_target->name);
 145                 return EINVAL;
 146         }
 147
 148         lockmgr(&dm_target_mutex, LK_EXCLUSIVE);
 149
 150         dmt = dm_target_lookup_name(dm_target->name);
 151         if (dmt != NULL) {
 152                 kprintf("uhoh, target_insert EEXIST\n");
 153                 lockmgr(&dm_target_mutex, LK_RELEASE);
 154                 return EEXIST;
 155         }
 156         TAILQ_INSERT_TAIL(&dm_target_list, dm_target, dm_target_next);
 157
 158         lockmgr(&dm_target_mutex, LK_RELEASE);
 159
 160         return 0;
 161 }
 162
 163 /*
 164  * Remove target from TAILQ, target is selected with it's name.
 165  */
 166 int
 167 dm_target_remove(char *dm_target_name)
 168 {
 169         dm_target_t *dmt;
 170
 171         KKASSERT(dm_target_name != NULL);
 172
 173         lockmgr(&dm_target_mutex, LK_EXCLUSIVE);
 174
 175         dmt = dm_target_lookup_name(dm_target_name);
 176         if (dmt == NULL) {
 177                 lockmgr(&dm_target_mutex, LK_RELEASE);
 178                 return ENOENT;
 179         }
 180         if (dmt->ref_cnt > 0) {
 181                 lockmgr(&dm_target_mutex, LK_RELEASE);
 182                 return EBUSY;
 183         }
 184         TAILQ_REMOVE(&dm_target_list, dmt, dm_target_next);
 185
 186         lockmgr(&dm_target_mutex, LK_RELEASE);
 187
 188         dm_target_free(dmt);
 189
 190         return 0;
 191 }
 192
 193 /*
 194  * Allocate new target entry.
 195  */
 196 dm_target_t *
 197 dm_target_alloc(const char *name)
 198 {
 199         dm_target_t *dmt;
 200
 201         dmt = kmalloc(sizeof(*dmt), M_DM, M_WAITOK | M_ZERO);
 202         if (dmt == NULL)
 203                 return NULL;
 204
 205         if (name)
 206                 strlcpy(dmt->name, name, sizeof(dmt->name));
 207
 208         return dmt;
 209 }
 210
 211 int
 212 dm_target_free(dm_target_t *dmt)
 213 {
 214         KKASSERT(dmt != NULL);
 215
 216         kfree(dmt, M_DM);
 217
 218         return 0;
 219 }
 220
 221 /*
 222  * Return prop_array of dm_target dictionaries.
 223  */
 224 prop_array_t
 225 dm_target_prop_list(void)
 226 {
 227         prop_array_t target_array, ver;
 228         prop_dictionary_t target_dict;
 229         dm_target_t *dm_target;
 230
 231         size_t i;
 232
 233         target_array = prop_array_create();
 234
 235         lockmgr(&dm_target_mutex, LK_EXCLUSIVE);
 236
 237         TAILQ_FOREACH(dm_target, &dm_target_list, dm_target_next) {
 238
 239                 target_dict = prop_dictionary_create();
 240                 ver = prop_array_create();
 241                 prop_dictionary_set_cstring(target_dict, DM_TARGETS_NAME,
 242                     dm_target->name);
 243
 244                 for (i = 0; i < 3; i++)
 245                         prop_array_add_uint32(ver, dm_target->version[i]);
 246
 247                 prop_dictionary_set(target_dict, DM_TARGETS_VERSION, ver);
 248                 prop_array_add(target_array, target_dict);
 249
 250                 prop_object_release(ver);
 251                 prop_object_release(target_dict);
 252         }
 253
 254         lockmgr(&dm_target_mutex, LK_RELEASE);
 255
 256         return target_array;
 257 }
 258
 259 /*
 260  * Initialize dm_target subsystem.
 261  */
 262 int
 263 dm_target_init(void)
 264 {
 265         TAILQ_INIT(&dm_target_list);    /* initialize global target list */
 266         lockinit(&dm_target_mutex, "dmtrgt", 0, LK_CANRECURSE);
 267
 268         return 0;
 269 }
 270
 271 /*
 272  * Destroy all targets and remove them from queue.
 273  * This routine is called from dmdestroy, before module
 274  * is unloaded.
 275  */
 276 int
 277 dm_target_uninit(void)
 278 {
 279         dm_target_t *dm_target;
 280
 281         lockmgr(&dm_target_mutex, LK_EXCLUSIVE);
 282
 283         while ((dm_target = TAILQ_FIRST(&dm_target_list)) != NULL) {
 284                 TAILQ_REMOVE(&dm_target_list, dm_target, dm_target_next);
 285                 dm_target_free(dm_target);
 286         }
 287         KKASSERT(TAILQ_EMPTY(&dm_target_list));
 288
 289         lockmgr(&dm_target_mutex, LK_RELEASE);
 290
 291         lockuninit(&dm_target_mutex);
 292
 293         return 0;
 294 }