drivers/nvdimm/dimm_devs.c

   1 /*
   2  * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  */
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14 #include <linux/vmalloc.h>
  15 #include <linux/device.h>
  16 #include <linux/ndctl.h>
  17 #include <linux/slab.h>
  18 #include <linux/io.h>
  19 #include <linux/fs.h>
  20 #include <linux/mm.h>
  21 #include "nd-core.h"
  22 #include "label.h"
  23 #include "nd.h"
  24
  25 static DEFINE_IDA(dimm_ida);
  26
  27 /*
  28  * Retrieve bus and dimm handle and return if this bus supports
  29  * get_config_data commands
  30  */
  31 int nvdimm_check_config_data(struct device *dev)
  32 {
  33         struct nvdimm *nvdimm = to_nvdimm(dev);
  34
  35         if (!nvdimm->cmd_mask ||
  36             !test_bit(ND_CMD_GET_CONFIG_DATA, &nvdimm->cmd_mask)) {
  37                 if (nvdimm->flags & NDD_ALIASING)
  38                         return -ENXIO;
  39                 else
  40                         return -ENOTTY;
  41         }
  42
  43         return 0;
  44 }
  45
  46 static int validate_dimm(struct nvdimm_drvdata *ndd)
  47 {
  48         int rc;
  49
  50         if (!ndd)
  51                 return -EINVAL;
  52
  53         rc = nvdimm_check_config_data(ndd->dev);
  54         if (rc)
  55                 dev_dbg(ndd->dev, "%pf: %s error: %d\n",
  56                                 __builtin_return_address(0), __func__, rc);
  57         return rc;
  58 }
  59
  60 /**
  61  * nvdimm_init_nsarea - determine the geometry of a dimm's namespace area
  62  * @nvdimm: dimm to initialize
  63  */
  64 int nvdimm_init_nsarea(struct nvdimm_drvdata *ndd)
  65 {
  66         struct nd_cmd_get_config_size *cmd = &ndd->nsarea;
  67         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
  68         struct nvdimm_bus_descriptor *nd_desc;
  69         int rc = validate_dimm(ndd);
  70
  71         if (rc)
  72                 return rc;
  73
  74         if (cmd->config_size)
  75                 return 0; /* already valid */
  76
  77         memset(cmd, 0, sizeof(*cmd));
  78         nd_desc = nvdimm_bus->nd_desc;
  79         return nd_desc->ndctl(nd_desc, to_nvdimm(ndd->dev),
  80                         ND_CMD_GET_CONFIG_SIZE, cmd, sizeof(*cmd), NULL);
  81 }
  82
  83 int nvdimm_init_config_data(struct nvdimm_drvdata *ndd)
  84 {
  85         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
  86         struct nd_cmd_get_config_data_hdr *cmd;
  87         struct nvdimm_bus_descriptor *nd_desc;
  88         int rc = validate_dimm(ndd);
  89         u32 max_cmd_size, config_size;
  90         size_t offset;
  91
  92         if (rc)
  93                 return rc;
  94
  95         if (ndd->data)
  96                 return 0;
  97
  98         if (ndd->nsarea.status || ndd->nsarea.max_xfer == 0
  99                         || ndd->nsarea.config_size < ND_LABEL_MIN_SIZE) {
 100                 dev_dbg(ndd->dev, "failed to init config data area: (%d:%d)\n",
 101                                 ndd->nsarea.max_xfer, ndd->nsarea.config_size);
 102                 return -ENXIO;
 103         }
 104
 105         ndd->data = kmalloc(ndd->nsarea.config_size, GFP_KERNEL);
 106         if (!ndd->data)
 107                 ndd->data = vmalloc(ndd->nsarea.config_size);
 108
 109         if (!ndd->data)
 110                 return -ENOMEM;
 111
 112         max_cmd_size = min_t(u32, PAGE_SIZE, ndd->nsarea.max_xfer);
 113         cmd = kzalloc(max_cmd_size + sizeof(*cmd), GFP_KERNEL);
 114         if (!cmd)
 115                 return -ENOMEM;
 116
 117         nd_desc = nvdimm_bus->nd_desc;
 118         for (config_size = ndd->nsarea.config_size, offset = 0;
 119                         config_size; config_size -= cmd->in_length,
 120                         offset += cmd->in_length) {
 121                 cmd->in_length = min(config_size, max_cmd_size);
 122                 cmd->in_offset = offset;
 123                 rc = nd_desc->ndctl(nd_desc, to_nvdimm(ndd->dev),
 124                                 ND_CMD_GET_CONFIG_DATA, cmd,
 125                                 cmd->in_length + sizeof(*cmd), NULL);
 126                 if (rc || cmd->status) {
 127                         rc = -ENXIO;
 128                         break;
 129                 }
 130                 memcpy(ndd->data + offset, cmd->out_buf, cmd->in_length);
 131         }
 132         dev_dbg(ndd->dev, "%s: len: %zu rc: %d\n", __func__, offset, rc);
 133         kfree(cmd);
 134
 135         return rc;
 136 }
 137
 138 int nvdimm_set_config_data(struct nvdimm_drvdata *ndd, size_t offset,
 139                 void *buf, size_t len)
 140 {
 141         int rc = validate_dimm(ndd);
 142         size_t max_cmd_size, buf_offset;
 143         struct nd_cmd_set_config_hdr *cmd;
 144         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
 145         struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;
 146
 147         if (rc)
 148                 return rc;
 149
 150         if (!ndd->data)
 151                 return -ENXIO;
 152
 153         if (offset + len > ndd->nsarea.config_size)
 154                 return -ENXIO;
 155
 156         max_cmd_size = min_t(u32, PAGE_SIZE, len);
 157         max_cmd_size = min_t(u32, max_cmd_size, ndd->nsarea.max_xfer);
 158         cmd = kzalloc(max_cmd_size + sizeof(*cmd) + sizeof(u32), GFP_KERNEL);
 159         if (!cmd)
 160                 return -ENOMEM;
 161
 162         for (buf_offset = 0; len; len -= cmd->in_length,
 163                         buf_offset += cmd->in_length) {
 164                 size_t cmd_size;
 165                 u32 *status;
 166
 167                 cmd->in_offset = offset + buf_offset;
 168                 cmd->in_length = min(max_cmd_size, len);
 169                 memcpy(cmd->in_buf, buf + buf_offset, cmd->in_length);
 170
 171                 /* status is output in the last 4-bytes of the command buffer */
 172                 cmd_size = sizeof(*cmd) + cmd->in_length + sizeof(u32);
 173                 status = ((void *) cmd) + cmd_size - sizeof(u32);
 174
 175                 rc = nd_desc->ndctl(nd_desc, to_nvdimm(ndd->dev),
 176                                 ND_CMD_SET_CONFIG_DATA, cmd, cmd_size, NULL);
 177                 if (rc || *status) {
 178                         rc = rc ? rc : -ENXIO;
 179                         break;
 180                 }
 181         }
 182         kfree(cmd);
 183
 184         return rc;
 185 }
 186
 187 static void nvdimm_release(struct device *dev)
 188 {
 189         struct nvdimm *nvdimm = to_nvdimm(dev);
 190
 191         ida_simple_remove(&dimm_ida, nvdimm->id);
 192         kfree(nvdimm);
 193 }
 194
 195 static struct device_type nvdimm_device_type = {
 196         .name = "nvdimm",
 197         .release = nvdimm_release,
 198 };
 199
 200 bool is_nvdimm(struct device *dev)
 201 {
 202         return dev->type == &nvdimm_device_type;
 203 }
 204
 205 struct nvdimm *to_nvdimm(struct device *dev)
 206 {
 207         struct nvdimm *nvdimm = container_of(dev, struct nvdimm, dev);
 208
 209         WARN_ON(!is_nvdimm(dev));
 210         return nvdimm;
 211 }
 212 EXPORT_SYMBOL_GPL(to_nvdimm);
 213
 214 struct nvdimm *nd_blk_region_to_dimm(struct nd_blk_region *ndbr)
 215 {
 216         struct nd_region *nd_region = &ndbr->nd_region;
 217         struct nd_mapping *nd_mapping = &nd_region->mapping[0];
 218
 219         return nd_mapping->nvdimm;
 220 }
 221 EXPORT_SYMBOL_GPL(nd_blk_region_to_dimm);
 222
 223 struct nvdimm_drvdata *to_ndd(struct nd_mapping *nd_mapping)
 224 {
 225         struct nvdimm *nvdimm = nd_mapping->nvdimm;
 226
 227         WARN_ON_ONCE(!is_nvdimm_bus_locked(&nvdimm->dev));
 228
 229         return dev_get_drvdata(&nvdimm->dev);
 230 }
 231 EXPORT_SYMBOL(to_ndd);
 232
 233 void nvdimm_drvdata_release(struct kref *kref)
 234 {
 235         struct nvdimm_drvdata *ndd = container_of(kref, typeof(*ndd), kref);
 236         struct device *dev = ndd->dev;
 237         struct resource *res, *_r;
 238
 239         dev_dbg(dev, "%s\n", __func__);
 240
 241         nvdimm_bus_lock(dev);
 242         for_each_dpa_resource_safe(ndd, res, _r)
 243                 nvdimm_free_dpa(ndd, res);
 244         nvdimm_bus_unlock(dev);
 245
 246         kvfree(ndd->data);
 247         kfree(ndd);
 248         put_device(dev);
 249 }
 250
 251 void get_ndd(struct nvdimm_drvdata *ndd)
 252 {
 253         kref_get(&ndd->kref);
 254 }
 255
 256 void put_ndd(struct nvdimm_drvdata *ndd)
 257 {
 258         if (ndd)
 259                 kref_put(&ndd->kref, nvdimm_drvdata_release);
 260 }
 261
 262 const char *nvdimm_name(struct nvdimm *nvdimm)
 263 {
 264         return dev_name(&nvdimm->dev);
 265 }
 266 EXPORT_SYMBOL_GPL(nvdimm_name);
 267
 268 struct kobject *nvdimm_kobj(struct nvdimm *nvdimm)
 269 {
 270         return &nvdimm->dev.kobj;
 271 }
 272 EXPORT_SYMBOL_GPL(nvdimm_kobj);
 273
 274 unsigned long nvdimm_cmd_mask(struct nvdimm *nvdimm)
 275 {
 276         return nvdimm->cmd_mask;
 277 }
 278 EXPORT_SYMBOL_GPL(nvdimm_cmd_mask);
 279
 280 void *nvdimm_provider_data(struct nvdimm *nvdimm)
 281 {
 282         if (nvdimm)
 283                 return nvdimm->provider_data;
 284         return NULL;
 285 }
 286 EXPORT_SYMBOL_GPL(nvdimm_provider_data);
 287
 288 static ssize_t commands_show(struct device *dev,
 289                 struct device_attribute *attr, char *buf)
 290 {
 291         struct nvdimm *nvdimm = to_nvdimm(dev);
 292         int cmd, len = 0;
 293
 294         if (!nvdimm->cmd_mask)
 295                 return sprintf(buf, "\n");
 296
 297         for_each_set_bit(cmd, &nvdimm->cmd_mask, BITS_PER_LONG)
 298                 len += sprintf(buf + len, "%s ", nvdimm_cmd_name(cmd));
 299         len += sprintf(buf + len, "\n");
 300         return len;
 301 }
 302 static DEVICE_ATTR_RO(commands);
 303
 304 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 305                 char *buf)
 306 {
 307         struct nvdimm *nvdimm = to_nvdimm(dev);
 308
 309         /*
 310          * The state may be in the process of changing, userspace should
 311          * quiesce probing if it wants a static answer
 312          */
 313         nvdimm_bus_lock(dev);
 314         nvdimm_bus_unlock(dev);
 315         return sprintf(buf, "%s\n", atomic_read(&nvdimm->busy)
 316                         ? "active" : "idle");
 317 }
 318 static DEVICE_ATTR_RO(state);
 319
 320 static ssize_t __available_slots_show(struct nvdimm_drvdata *ndd, char *buf)
 321 {
 322         struct device *dev;
 323         ssize_t rc;
 324         u32 nfree;
 325
 326         if (!ndd)
 327                 return -ENXIO;
 328
 329         dev = ndd->dev;
 330         nvdimm_bus_lock(dev);
 331         nfree = nd_label_nfree(ndd);
 332         if (nfree - 1 > nfree) {
 333                 dev_WARN_ONCE(dev, 1, "we ate our last label?\n");
 334                 nfree = 0;
 335         } else
 336                 nfree--;
 337         rc = sprintf(buf, "%d\n", nfree);
 338         nvdimm_bus_unlock(dev);
 339         return rc;
 340 }
 341
 342 static ssize_t available_slots_show(struct device *dev,
 343                                     struct device_attribute *attr, char *buf)
 344 {
 345         ssize_t rc;
 346
 347         device_lock(dev);
 348         rc = __available_slots_show(dev_get_drvdata(dev), buf);
 349         device_unlock(dev);
 350
 351         return rc;
 352 }
 353 static DEVICE_ATTR_RO(available_slots);
 354
 355 static struct attribute *nvdimm_attributes[] = {
 356         &dev_attr_state.attr,
 357         &dev_attr_commands.attr,
 358         &dev_attr_available_slots.attr,
 359         NULL,
 360 };
 361
 362 struct attribute_group nvdimm_attribute_group = {
 363         .attrs = nvdimm_attributes,
 364 };
 365 EXPORT_SYMBOL_GPL(nvdimm_attribute_group);
 366
 367 struct nvdimm *nvdimm_create(struct nvdimm_bus *nvdimm_bus, void *provider_data,
 368                 const struct attribute_group **groups, unsigned long flags,
 369                 unsigned long cmd_mask, int num_flush,
 370                 struct resource *flush_wpq)
 371 {
 372         struct nvdimm *nvdimm = kzalloc(sizeof(*nvdimm), GFP_KERNEL);
 373         struct device *dev;
 374
 375         if (!nvdimm)
 376                 return NULL;
 377
 378         nvdimm->id = ida_simple_get(&dimm_ida, 0, 0, GFP_KERNEL);
 379         if (nvdimm->id < 0) {
 380                 kfree(nvdimm);
 381                 return NULL;
 382         }
 383         nvdimm->provider_data = provider_data;
 384         nvdimm->flags = flags;
 385         nvdimm->cmd_mask = cmd_mask;
 386         nvdimm->num_flush = num_flush;
 387         nvdimm->flush_wpq = flush_wpq;
 388         atomic_set(&nvdimm->busy, 0);
 389         dev = &nvdimm->dev;
 390         dev_set_name(dev, "nmem%d", nvdimm->id);
 391         dev->parent = &nvdimm_bus->dev;
 392         dev->type = &nvdimm_device_type;
 393         dev->devt = MKDEV(nvdimm_major, nvdimm->id);
 394         dev->groups = groups;
 395         nd_device_register(dev);
 396
 397         return nvdimm;
 398 }
 399 EXPORT_SYMBOL_GPL(nvdimm_create);
 400
 401 int alias_dpa_busy(struct device *dev, void *data)
 402 {
 403         resource_size_t map_end, blk_start, new;
 404         struct blk_alloc_info *info = data;
 405         struct nd_mapping *nd_mapping;
 406         struct nd_region *nd_region;
 407         struct nvdimm_drvdata *ndd;
 408         struct resource *res;
 409         int i;
 410
 411         if (!is_nd_pmem(dev))
 412                 return 0;
 413
 414         nd_region = to_nd_region(dev);
 415         for (i = 0; i < nd_region->ndr_mappings; i++) {
 416                 nd_mapping  = &nd_region->mapping[i];
 417                 if (nd_mapping->nvdimm == info->nd_mapping->nvdimm)
 418                         break;
 419         }
 420
 421         if (i >= nd_region->ndr_mappings)
 422                 return 0;
 423
 424         ndd = to_ndd(nd_mapping);
 425         map_end = nd_mapping->start + nd_mapping->size - 1;
 426         blk_start = nd_mapping->start;
 427
 428         /*
 429          * In the allocation case ->res is set to free space that we are
 430          * looking to validate against PMEM aliasing collision rules
 431          * (i.e. BLK is allocated after all aliased PMEM).
 432          */
 433         if (info->res) {
 434                 if (info->res->start >= nd_mapping->start
 435                                 && info->res->start < map_end)
 436                         /* pass */;
 437                 else
 438                         return 0;
 439         }
 440
 441  retry:
 442         /*
 443          * Find the free dpa from the end of the last pmem allocation to
 444          * the end of the interleave-set mapping.
 445          */
 446         for_each_dpa_resource(ndd, res) {
 447                 if (strncmp(res->name, "pmem", 4) != 0)
 448                         continue;
 449                 if ((res->start >= blk_start && res->start < map_end)
 450                                 || (res->end >= blk_start
 451                                         && res->end <= map_end)) {
 452                         new = max(blk_start, min(map_end + 1, res->end + 1));
 453                         if (new != blk_start) {
 454                                 blk_start = new;
 455                                 goto retry;
 456                         }
 457                 }
 458         }
 459
 460         /* update the free space range with the probed blk_start */
 461         if (info->res && blk_start > info->res->start) {
 462                 info->res->start = max(info->res->start, blk_start);
 463                 if (info->res->start > info->res->end)
 464                         info->res->end = info->res->start - 1;
 465                 return 1;
 466         }
 467
 468         info->available -= blk_start - nd_mapping->start;
 469
 470         return 0;
 471 }
 472
 473 /**
 474  * nd_blk_available_dpa - account the unused dpa of BLK region
 475  * @nd_mapping: container of dpa-resource-root + labels
 476  *
 477  * Unlike PMEM, BLK namespaces can occupy discontiguous DPA ranges, but
 478  * we arrange for them to never start at an lower dpa than the last
 479  * PMEM allocation in an aliased region.
 480  */
 481 resource_size_t nd_blk_available_dpa(struct nd_region *nd_region)
 482 {
 483         struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&nd_region->dev);
 484         struct nd_mapping *nd_mapping = &nd_region->mapping[0];
 485         struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
 486         struct blk_alloc_info info = {
 487                 .nd_mapping = nd_mapping,
 488                 .available = nd_mapping->size,
 489                 .res = NULL,
 490         };
 491         struct resource *res;
 492
 493         if (!ndd)
 494                 return 0;
 495
 496         device_for_each_child(&nvdimm_bus->dev, &info, alias_dpa_busy);
 497
 498         /* now account for busy blk allocations in unaliased dpa */
 499         for_each_dpa_resource(ndd, res) {
 500                 if (strncmp(res->name, "blk", 3) != 0)
 501                         continue;
 502                 info.available -= resource_size(res);
 503         }
 504
 505         return info.available;
 506 }
 507
 508 /**
 509  * nd_pmem_available_dpa - for the given dimm+region account unallocated dpa
 510  * @nd_mapping: container of dpa-resource-root + labels
 511  * @nd_region: constrain available space check to this reference region
 512  * @overlap: calculate available space assuming this level of overlap
 513  *
 514  * Validate that a PMEM label, if present, aligns with the start of an
 515  * interleave set and truncate the available size at the lowest BLK
 516  * overlap point.
 517  *
 518  * The expectation is that this routine is called multiple times as it
 519  * probes for the largest BLK encroachment for any single member DIMM of
 520  * the interleave set.  Once that value is determined the PMEM-limit for
 521  * the set can be established.
 522  */
 523 resource_size_t nd_pmem_available_dpa(struct nd_region *nd_region,
 524                 struct nd_mapping *nd_mapping, resource_size_t *overlap)
 525 {
 526         resource_size_t map_start, map_end, busy = 0, available, blk_start;
 527         struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
 528         struct resource *res;
 529         const char *reason;
 530
 531         if (!ndd)
 532                 return 0;
 533
 534         map_start = nd_mapping->start;
 535         map_end = map_start + nd_mapping->size - 1;
 536         blk_start = max(map_start, map_end + 1 - *overlap);
 537         for_each_dpa_resource(ndd, res) {
 538                 if (res->start >= map_start && res->start < map_end) {
 539                         if (strncmp(res->name, "blk", 3) == 0)
 540                                 blk_start = min(blk_start,
 541                                                 max(map_start, res->start));
 542                         else if (res->end > map_end) {
 543                                 reason = "misaligned to iset";
 544                                 goto err;
 545                         } else
 546                                 busy += resource_size(res);
 547                 } else if (res->end >= map_start && res->end <= map_end) {
 548                         if (strncmp(res->name, "blk", 3) == 0) {
 549                                 /*
 550                                  * If a BLK allocation overlaps the start of
 551                                  * PMEM the entire interleave set may now only
 552                                  * be used for BLK.
 553                                  */
 554                                 blk_start = map_start;
 555                         } else
 556                                 busy += resource_size(res);
 557                 } else if (map_start > res->start && map_start < res->end) {
 558                         /* total eclipse of the mapping */
 559                         busy += nd_mapping->size;
 560                         blk_start = map_start;
 561                 }
 562         }
 563
 564         *overlap = map_end + 1 - blk_start;
 565         available = blk_start - map_start;
 566         if (busy < available)
 567                 return available - busy;
 568         return 0;
 569
 570  err:
 571         nd_dbg_dpa(nd_region, ndd, res, "%s\n", reason);
 572         return 0;
 573 }
 574
 575 void nvdimm_free_dpa(struct nvdimm_drvdata *ndd, struct resource *res)
 576 {
 577         WARN_ON_ONCE(!is_nvdimm_bus_locked(ndd->dev));
 578         kfree(res->name);
 579         __release_region(&ndd->dpa, res->start, resource_size(res));
 580 }
 581
 582 struct resource *nvdimm_allocate_dpa(struct nvdimm_drvdata *ndd,
 583                 struct nd_label_id *label_id, resource_size_t start,
 584                 resource_size_t n)
 585 {
 586         char *name = kmemdup(label_id, sizeof(*label_id), GFP_KERNEL);
 587         struct resource *res;
 588
 589         if (!name)
 590                 return NULL;
 591
 592         WARN_ON_ONCE(!is_nvdimm_bus_locked(ndd->dev));
 593         res = __request_region(&ndd->dpa, start, n, name, 0);
 594         if (!res)
 595                 kfree(name);
 596         return res;
 597 }
 598
 599 /**
 600  * nvdimm_allocated_dpa - sum up the dpa currently allocated to this label_id
 601  * @nvdimm: container of dpa-resource-root + labels
 602  * @label_id: dpa resource name of the form {pmem|blk}-<human readable uuid>
 603  */
 604 resource_size_t nvdimm_allocated_dpa(struct nvdimm_drvdata *ndd,
 605                 struct nd_label_id *label_id)
 606 {
 607         resource_size_t allocated = 0;
 608         struct resource *res;
 609
 610         for_each_dpa_resource(ndd, res)
 611                 if (strcmp(res->name, label_id->id) == 0)
 612                         allocated += resource_size(res);
 613
 614         return allocated;
 615 }
 616
 617 static int count_dimms(struct device *dev, void *c)
 618 {
 619         int *count = c;
 620
 621         if (is_nvdimm(dev))
 622                 (*count)++;
 623         return 0;
 624 }
 625
 626 int nvdimm_bus_check_dimm_count(struct nvdimm_bus *nvdimm_bus, int dimm_count)
 627 {
 628         int count = 0;
 629         /* Flush any possible dimm registration failures */
 630         nd_synchronize();
 631
 632         device_for_each_child(&nvdimm_bus->dev, &count, count_dimms);
 633         dev_dbg(&nvdimm_bus->dev, "%s: count: %d\n", __func__, count);
 634         if (count != dimm_count)
 635                 return -ENXIO;
 636         return 0;
 637 }
 638 EXPORT_SYMBOL_GPL(nvdimm_bus_check_dimm_count);
 639
 640 void __exit nvdimm_devs_exit(void)
 641 {
 642         ida_destroy(&dimm_ida);
 643 }