bus.c 34 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /* Copyright(c) 2017-2018 Intel Corporation. All rights reserved. */
  3. #include <linux/memremap.h>
  4. #include <linux/device.h>
  5. #include <linux/mutex.h>
  6. #include <linux/list.h>
  7. #include <linux/slab.h>
  8. #include <linux/dax.h>
  9. #include <linux/io.h>
  10. #include "dax-private.h"
  11. #include "bus.h"
  12. static struct class *dax_class;
  13. static DEFINE_MUTEX(dax_bus_lock);
  14. #define DAX_NAME_LEN 30
  15. struct dax_id {
  16. struct list_head list;
  17. char dev_name[DAX_NAME_LEN];
  18. };
  19. static int dax_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
  20. {
  21. /*
  22. * We only ever expect to handle device-dax instances, i.e. the
  23. * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
  24. */
  25. return add_uevent_var(env, "MODALIAS=" DAX_DEVICE_MODALIAS_FMT, 0);
  26. }
  27. static struct dax_device_driver *to_dax_drv(struct device_driver *drv)
  28. {
  29. return container_of(drv, struct dax_device_driver, drv);
  30. }
  31. static struct dax_id *__dax_match_id(struct dax_device_driver *dax_drv,
  32. const char *dev_name)
  33. {
  34. struct dax_id *dax_id;
  35. lockdep_assert_held(&dax_bus_lock);
  36. list_for_each_entry(dax_id, &dax_drv->ids, list)
  37. if (sysfs_streq(dax_id->dev_name, dev_name))
  38. return dax_id;
  39. return NULL;
  40. }
  41. static int dax_match_id(struct dax_device_driver *dax_drv, struct device *dev)
  42. {
  43. int match;
  44. mutex_lock(&dax_bus_lock);
  45. match = !!__dax_match_id(dax_drv, dev_name(dev));
  46. mutex_unlock(&dax_bus_lock);
  47. return match;
  48. }
  49. enum id_action {
  50. ID_REMOVE,
  51. ID_ADD,
  52. };
  53. static ssize_t do_id_store(struct device_driver *drv, const char *buf,
  54. size_t count, enum id_action action)
  55. {
  56. struct dax_device_driver *dax_drv = to_dax_drv(drv);
  57. unsigned int region_id, id;
  58. char devname[DAX_NAME_LEN];
  59. struct dax_id *dax_id;
  60. ssize_t rc = count;
  61. int fields;
  62. fields = sscanf(buf, "dax%d.%d", &region_id, &id);
  63. if (fields != 2)
  64. return -EINVAL;
  65. sprintf(devname, "dax%d.%d", region_id, id);
  66. if (!sysfs_streq(buf, devname))
  67. return -EINVAL;
  68. mutex_lock(&dax_bus_lock);
  69. dax_id = __dax_match_id(dax_drv, buf);
  70. if (!dax_id) {
  71. if (action == ID_ADD) {
  72. dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
  73. if (dax_id) {
  74. strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
  75. list_add(&dax_id->list, &dax_drv->ids);
  76. } else
  77. rc = -ENOMEM;
  78. } else
  79. /* nothing to remove */;
  80. } else if (action == ID_REMOVE) {
  81. list_del(&dax_id->list);
  82. kfree(dax_id);
  83. } else
  84. /* dax_id already added */;
  85. mutex_unlock(&dax_bus_lock);
  86. if (rc < 0)
  87. return rc;
  88. if (action == ID_ADD)
  89. rc = driver_attach(drv);
  90. if (rc)
  91. return rc;
  92. return count;
  93. }
  94. static ssize_t new_id_store(struct device_driver *drv, const char *buf,
  95. size_t count)
  96. {
  97. return do_id_store(drv, buf, count, ID_ADD);
  98. }
  99. static DRIVER_ATTR_WO(new_id);
  100. static ssize_t remove_id_store(struct device_driver *drv, const char *buf,
  101. size_t count)
  102. {
  103. return do_id_store(drv, buf, count, ID_REMOVE);
  104. }
  105. static DRIVER_ATTR_WO(remove_id);
  106. static struct attribute *dax_drv_attrs[] = {
  107. &driver_attr_new_id.attr,
  108. &driver_attr_remove_id.attr,
  109. NULL,
  110. };
  111. ATTRIBUTE_GROUPS(dax_drv);
  112. static int dax_bus_match(struct device *dev, struct device_driver *drv);
  113. static bool is_static(struct dax_region *dax_region)
  114. {
  115. return (dax_region->res.flags & IORESOURCE_DAX_STATIC) != 0;
  116. }
  117. static u64 dev_dax_size(struct dev_dax *dev_dax)
  118. {
  119. u64 size = 0;
  120. int i;
  121. device_lock_assert(&dev_dax->dev);
  122. for (i = 0; i < dev_dax->nr_range; i++)
  123. size += range_len(&dev_dax->ranges[i].range);
  124. return size;
  125. }
  126. static int dax_bus_probe(struct device *dev)
  127. {
  128. struct dax_device_driver *dax_drv = to_dax_drv(dev->driver);
  129. struct dev_dax *dev_dax = to_dev_dax(dev);
  130. struct dax_region *dax_region = dev_dax->region;
  131. int rc;
  132. if (dev_dax_size(dev_dax) == 0 || dev_dax->id < 0)
  133. return -ENXIO;
  134. rc = dax_drv->probe(dev_dax);
  135. if (rc || is_static(dax_region))
  136. return rc;
  137. /*
  138. * Track new seed creation only after successful probe of the
  139. * previous seed.
  140. */
  141. if (dax_region->seed == dev)
  142. dax_region->seed = NULL;
  143. return 0;
  144. }
  145. static int dax_bus_remove(struct device *dev)
  146. {
  147. struct dax_device_driver *dax_drv = to_dax_drv(dev->driver);
  148. struct dev_dax *dev_dax = to_dev_dax(dev);
  149. return dax_drv->remove(dev_dax);
  150. }
  151. static struct bus_type dax_bus_type = {
  152. .name = "dax",
  153. .uevent = dax_bus_uevent,
  154. .match = dax_bus_match,
  155. .probe = dax_bus_probe,
  156. .remove = dax_bus_remove,
  157. .drv_groups = dax_drv_groups,
  158. };
  159. static int dax_bus_match(struct device *dev, struct device_driver *drv)
  160. {
  161. struct dax_device_driver *dax_drv = to_dax_drv(drv);
  162. /*
  163. * All but the 'device-dax' driver, which has 'match_always'
  164. * set, requires an exact id match.
  165. */
  166. if (dax_drv->match_always)
  167. return 1;
  168. return dax_match_id(dax_drv, dev);
  169. }
  170. /*
  171. * Rely on the fact that drvdata is set before the attributes are
  172. * registered, and that the attributes are unregistered before drvdata
  173. * is cleared to assume that drvdata is always valid.
  174. */
  175. static ssize_t id_show(struct device *dev,
  176. struct device_attribute *attr, char *buf)
  177. {
  178. struct dax_region *dax_region = dev_get_drvdata(dev);
  179. return sprintf(buf, "%d\n", dax_region->id);
  180. }
  181. static DEVICE_ATTR_RO(id);
  182. static ssize_t region_size_show(struct device *dev,
  183. struct device_attribute *attr, char *buf)
  184. {
  185. struct dax_region *dax_region = dev_get_drvdata(dev);
  186. return sprintf(buf, "%llu\n", (unsigned long long)
  187. resource_size(&dax_region->res));
  188. }
  189. static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
  190. region_size_show, NULL);
  191. static ssize_t region_align_show(struct device *dev,
  192. struct device_attribute *attr, char *buf)
  193. {
  194. struct dax_region *dax_region = dev_get_drvdata(dev);
  195. return sprintf(buf, "%u\n", dax_region->align);
  196. }
  197. static struct device_attribute dev_attr_region_align =
  198. __ATTR(align, 0400, region_align_show, NULL);
  199. #define for_each_dax_region_resource(dax_region, res) \
  200. for (res = (dax_region)->res.child; res; res = res->sibling)
  201. static unsigned long long dax_region_avail_size(struct dax_region *dax_region)
  202. {
  203. resource_size_t size = resource_size(&dax_region->res);
  204. struct resource *res;
  205. device_lock_assert(dax_region->dev);
  206. for_each_dax_region_resource(dax_region, res)
  207. size -= resource_size(res);
  208. return size;
  209. }
  210. static ssize_t available_size_show(struct device *dev,
  211. struct device_attribute *attr, char *buf)
  212. {
  213. struct dax_region *dax_region = dev_get_drvdata(dev);
  214. unsigned long long size;
  215. device_lock(dev);
  216. size = dax_region_avail_size(dax_region);
  217. device_unlock(dev);
  218. return sprintf(buf, "%llu\n", size);
  219. }
  220. static DEVICE_ATTR_RO(available_size);
  221. static ssize_t seed_show(struct device *dev,
  222. struct device_attribute *attr, char *buf)
  223. {
  224. struct dax_region *dax_region = dev_get_drvdata(dev);
  225. struct device *seed;
  226. ssize_t rc;
  227. if (is_static(dax_region))
  228. return -EINVAL;
  229. device_lock(dev);
  230. seed = dax_region->seed;
  231. rc = sprintf(buf, "%s\n", seed ? dev_name(seed) : "");
  232. device_unlock(dev);
  233. return rc;
  234. }
  235. static DEVICE_ATTR_RO(seed);
  236. static ssize_t create_show(struct device *dev,
  237. struct device_attribute *attr, char *buf)
  238. {
  239. struct dax_region *dax_region = dev_get_drvdata(dev);
  240. struct device *youngest;
  241. ssize_t rc;
  242. if (is_static(dax_region))
  243. return -EINVAL;
  244. device_lock(dev);
  245. youngest = dax_region->youngest;
  246. rc = sprintf(buf, "%s\n", youngest ? dev_name(youngest) : "");
  247. device_unlock(dev);
  248. return rc;
  249. }
  250. static ssize_t create_store(struct device *dev, struct device_attribute *attr,
  251. const char *buf, size_t len)
  252. {
  253. struct dax_region *dax_region = dev_get_drvdata(dev);
  254. unsigned long long avail;
  255. ssize_t rc;
  256. int val;
  257. if (is_static(dax_region))
  258. return -EINVAL;
  259. rc = kstrtoint(buf, 0, &val);
  260. if (rc)
  261. return rc;
  262. if (val != 1)
  263. return -EINVAL;
  264. device_lock(dev);
  265. avail = dax_region_avail_size(dax_region);
  266. if (avail == 0)
  267. rc = -ENOSPC;
  268. else {
  269. struct dev_dax_data data = {
  270. .dax_region = dax_region,
  271. .size = 0,
  272. .id = -1,
  273. };
  274. struct dev_dax *dev_dax = devm_create_dev_dax(&data);
  275. if (IS_ERR(dev_dax))
  276. rc = PTR_ERR(dev_dax);
  277. else {
  278. /*
  279. * In support of crafting multiple new devices
  280. * simultaneously multiple seeds can be created,
  281. * but only the first one that has not been
  282. * successfully bound is tracked as the region
  283. * seed.
  284. */
  285. if (!dax_region->seed)
  286. dax_region->seed = &dev_dax->dev;
  287. dax_region->youngest = &dev_dax->dev;
  288. rc = len;
  289. }
  290. }
  291. device_unlock(dev);
  292. return rc;
  293. }
  294. static DEVICE_ATTR_RW(create);
  295. void kill_dev_dax(struct dev_dax *dev_dax)
  296. {
  297. struct dax_device *dax_dev = dev_dax->dax_dev;
  298. struct inode *inode = dax_inode(dax_dev);
  299. kill_dax(dax_dev);
  300. unmap_mapping_range(inode->i_mapping, 0, 0, 1);
  301. }
  302. EXPORT_SYMBOL_GPL(kill_dev_dax);
  303. static void trim_dev_dax_range(struct dev_dax *dev_dax)
  304. {
  305. int i = dev_dax->nr_range - 1;
  306. struct range *range = &dev_dax->ranges[i].range;
  307. struct dax_region *dax_region = dev_dax->region;
  308. device_lock_assert(dax_region->dev);
  309. dev_dbg(&dev_dax->dev, "delete range[%d]: %#llx:%#llx\n", i,
  310. (unsigned long long)range->start,
  311. (unsigned long long)range->end);
  312. __release_region(&dax_region->res, range->start, range_len(range));
  313. if (--dev_dax->nr_range == 0) {
  314. kfree(dev_dax->ranges);
  315. dev_dax->ranges = NULL;
  316. }
  317. }
  318. static void free_dev_dax_ranges(struct dev_dax *dev_dax)
  319. {
  320. while (dev_dax->nr_range)
  321. trim_dev_dax_range(dev_dax);
  322. }
  323. static void unregister_dev_dax(void *dev)
  324. {
  325. struct dev_dax *dev_dax = to_dev_dax(dev);
  326. dev_dbg(dev, "%s\n", __func__);
  327. kill_dev_dax(dev_dax);
  328. free_dev_dax_ranges(dev_dax);
  329. device_del(dev);
  330. put_device(dev);
  331. }
  332. /* a return value >= 0 indicates this invocation invalidated the id */
  333. static int __free_dev_dax_id(struct dev_dax *dev_dax)
  334. {
  335. struct dax_region *dax_region = dev_dax->region;
  336. struct device *dev = &dev_dax->dev;
  337. int rc = dev_dax->id;
  338. device_lock_assert(dev);
  339. if (is_static(dax_region) || dev_dax->id < 0)
  340. return -1;
  341. ida_free(&dax_region->ida, dev_dax->id);
  342. dev_dax->id = -1;
  343. return rc;
  344. }
  345. static int free_dev_dax_id(struct dev_dax *dev_dax)
  346. {
  347. struct device *dev = &dev_dax->dev;
  348. int rc;
  349. device_lock(dev);
  350. rc = __free_dev_dax_id(dev_dax);
  351. device_unlock(dev);
  352. return rc;
  353. }
  354. static ssize_t delete_store(struct device *dev, struct device_attribute *attr,
  355. const char *buf, size_t len)
  356. {
  357. struct dax_region *dax_region = dev_get_drvdata(dev);
  358. struct dev_dax *dev_dax;
  359. struct device *victim;
  360. bool do_del = false;
  361. int rc;
  362. if (is_static(dax_region))
  363. return -EINVAL;
  364. victim = device_find_child_by_name(dax_region->dev, buf);
  365. if (!victim)
  366. return -ENXIO;
  367. device_lock(dev);
  368. device_lock(victim);
  369. dev_dax = to_dev_dax(victim);
  370. if (victim->driver || dev_dax_size(dev_dax))
  371. rc = -EBUSY;
  372. else {
  373. /*
  374. * Invalidate the device so it does not become active
  375. * again, but always preserve device-id-0 so that
  376. * /sys/bus/dax/ is guaranteed to be populated while any
  377. * dax_region is registered.
  378. */
  379. if (dev_dax->id > 0) {
  380. do_del = __free_dev_dax_id(dev_dax) >= 0;
  381. rc = len;
  382. if (dax_region->seed == victim)
  383. dax_region->seed = NULL;
  384. if (dax_region->youngest == victim)
  385. dax_region->youngest = NULL;
  386. } else
  387. rc = -EBUSY;
  388. }
  389. device_unlock(victim);
  390. /* won the race to invalidate the device, clean it up */
  391. if (do_del)
  392. devm_release_action(dev, unregister_dev_dax, victim);
  393. device_unlock(dev);
  394. put_device(victim);
  395. return rc;
  396. }
  397. static DEVICE_ATTR_WO(delete);
  398. static umode_t dax_region_visible(struct kobject *kobj, struct attribute *a,
  399. int n)
  400. {
  401. struct device *dev = container_of(kobj, struct device, kobj);
  402. struct dax_region *dax_region = dev_get_drvdata(dev);
  403. if (is_static(dax_region))
  404. if (a == &dev_attr_available_size.attr
  405. || a == &dev_attr_create.attr
  406. || a == &dev_attr_seed.attr
  407. || a == &dev_attr_delete.attr)
  408. return 0;
  409. return a->mode;
  410. }
  411. static struct attribute *dax_region_attributes[] = {
  412. &dev_attr_available_size.attr,
  413. &dev_attr_region_size.attr,
  414. &dev_attr_region_align.attr,
  415. &dev_attr_create.attr,
  416. &dev_attr_seed.attr,
  417. &dev_attr_delete.attr,
  418. &dev_attr_id.attr,
  419. NULL,
  420. };
  421. static const struct attribute_group dax_region_attribute_group = {
  422. .name = "dax_region",
  423. .attrs = dax_region_attributes,
  424. .is_visible = dax_region_visible,
  425. };
  426. static const struct attribute_group *dax_region_attribute_groups[] = {
  427. &dax_region_attribute_group,
  428. NULL,
  429. };
  430. static void dax_region_free(struct kref *kref)
  431. {
  432. struct dax_region *dax_region;
  433. dax_region = container_of(kref, struct dax_region, kref);
  434. kfree(dax_region);
  435. }
  436. void dax_region_put(struct dax_region *dax_region)
  437. {
  438. kref_put(&dax_region->kref, dax_region_free);
  439. }
  440. EXPORT_SYMBOL_GPL(dax_region_put);
  441. static void dax_region_unregister(void *region)
  442. {
  443. struct dax_region *dax_region = region;
  444. sysfs_remove_groups(&dax_region->dev->kobj,
  445. dax_region_attribute_groups);
  446. dax_region_put(dax_region);
  447. }
  448. struct dax_region *alloc_dax_region(struct device *parent, int region_id,
  449. struct range *range, int target_node, unsigned int align,
  450. unsigned long flags)
  451. {
  452. struct dax_region *dax_region;
  453. /*
  454. * The DAX core assumes that it can store its private data in
  455. * parent->driver_data. This WARN is a reminder / safeguard for
  456. * developers of device-dax drivers.
  457. */
  458. if (dev_get_drvdata(parent)) {
  459. dev_WARN(parent, "dax core failed to setup private data\n");
  460. return NULL;
  461. }
  462. if (!IS_ALIGNED(range->start, align)
  463. || !IS_ALIGNED(range_len(range), align))
  464. return NULL;
  465. dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
  466. if (!dax_region)
  467. return NULL;
  468. dev_set_drvdata(parent, dax_region);
  469. kref_init(&dax_region->kref);
  470. dax_region->id = region_id;
  471. dax_region->align = align;
  472. dax_region->dev = parent;
  473. dax_region->target_node = target_node;
  474. ida_init(&dax_region->ida);
  475. dax_region->res = (struct resource) {
  476. .start = range->start,
  477. .end = range->end,
  478. .flags = IORESOURCE_MEM | flags,
  479. };
  480. if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
  481. kfree(dax_region);
  482. return NULL;
  483. }
  484. kref_get(&dax_region->kref);
  485. if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
  486. return NULL;
  487. return dax_region;
  488. }
  489. EXPORT_SYMBOL_GPL(alloc_dax_region);
  490. static void dax_mapping_release(struct device *dev)
  491. {
  492. struct dax_mapping *mapping = to_dax_mapping(dev);
  493. struct dev_dax *dev_dax = to_dev_dax(dev->parent);
  494. ida_free(&dev_dax->ida, mapping->id);
  495. kfree(mapping);
  496. }
  497. static void unregister_dax_mapping(void *data)
  498. {
  499. struct device *dev = data;
  500. struct dax_mapping *mapping = to_dax_mapping(dev);
  501. struct dev_dax *dev_dax = to_dev_dax(dev->parent);
  502. struct dax_region *dax_region = dev_dax->region;
  503. dev_dbg(dev, "%s\n", __func__);
  504. device_lock_assert(dax_region->dev);
  505. dev_dax->ranges[mapping->range_id].mapping = NULL;
  506. mapping->range_id = -1;
  507. device_del(dev);
  508. put_device(dev);
  509. }
  510. static struct dev_dax_range *get_dax_range(struct device *dev)
  511. {
  512. struct dax_mapping *mapping = to_dax_mapping(dev);
  513. struct dev_dax *dev_dax = to_dev_dax(dev->parent);
  514. struct dax_region *dax_region = dev_dax->region;
  515. device_lock(dax_region->dev);
  516. if (mapping->range_id < 0) {
  517. device_unlock(dax_region->dev);
  518. return NULL;
  519. }
  520. return &dev_dax->ranges[mapping->range_id];
  521. }
  522. static void put_dax_range(struct dev_dax_range *dax_range)
  523. {
  524. struct dax_mapping *mapping = dax_range->mapping;
  525. struct dev_dax *dev_dax = to_dev_dax(mapping->dev.parent);
  526. struct dax_region *dax_region = dev_dax->region;
  527. device_unlock(dax_region->dev);
  528. }
  529. static ssize_t start_show(struct device *dev,
  530. struct device_attribute *attr, char *buf)
  531. {
  532. struct dev_dax_range *dax_range;
  533. ssize_t rc;
  534. dax_range = get_dax_range(dev);
  535. if (!dax_range)
  536. return -ENXIO;
  537. rc = sprintf(buf, "%#llx\n", dax_range->range.start);
  538. put_dax_range(dax_range);
  539. return rc;
  540. }
  541. static DEVICE_ATTR(start, 0400, start_show, NULL);
  542. static ssize_t end_show(struct device *dev,
  543. struct device_attribute *attr, char *buf)
  544. {
  545. struct dev_dax_range *dax_range;
  546. ssize_t rc;
  547. dax_range = get_dax_range(dev);
  548. if (!dax_range)
  549. return -ENXIO;
  550. rc = sprintf(buf, "%#llx\n", dax_range->range.end);
  551. put_dax_range(dax_range);
  552. return rc;
  553. }
  554. static DEVICE_ATTR(end, 0400, end_show, NULL);
  555. static ssize_t pgoff_show(struct device *dev,
  556. struct device_attribute *attr, char *buf)
  557. {
  558. struct dev_dax_range *dax_range;
  559. ssize_t rc;
  560. dax_range = get_dax_range(dev);
  561. if (!dax_range)
  562. return -ENXIO;
  563. rc = sprintf(buf, "%#lx\n", dax_range->pgoff);
  564. put_dax_range(dax_range);
  565. return rc;
  566. }
  567. static DEVICE_ATTR(page_offset, 0400, pgoff_show, NULL);
  568. static struct attribute *dax_mapping_attributes[] = {
  569. &dev_attr_start.attr,
  570. &dev_attr_end.attr,
  571. &dev_attr_page_offset.attr,
  572. NULL,
  573. };
  574. static const struct attribute_group dax_mapping_attribute_group = {
  575. .attrs = dax_mapping_attributes,
  576. };
  577. static const struct attribute_group *dax_mapping_attribute_groups[] = {
  578. &dax_mapping_attribute_group,
  579. NULL,
  580. };
  581. static struct device_type dax_mapping_type = {
  582. .release = dax_mapping_release,
  583. .groups = dax_mapping_attribute_groups,
  584. };
  585. static int devm_register_dax_mapping(struct dev_dax *dev_dax, int range_id)
  586. {
  587. struct dax_region *dax_region = dev_dax->region;
  588. struct dax_mapping *mapping;
  589. struct device *dev;
  590. int rc;
  591. device_lock_assert(dax_region->dev);
  592. if (dev_WARN_ONCE(&dev_dax->dev, !dax_region->dev->driver,
  593. "region disabled\n"))
  594. return -ENXIO;
  595. mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
  596. if (!mapping)
  597. return -ENOMEM;
  598. mapping->range_id = range_id;
  599. mapping->id = ida_alloc(&dev_dax->ida, GFP_KERNEL);
  600. if (mapping->id < 0) {
  601. kfree(mapping);
  602. return -ENOMEM;
  603. }
  604. dev_dax->ranges[range_id].mapping = mapping;
  605. dev = &mapping->dev;
  606. device_initialize(dev);
  607. dev->parent = &dev_dax->dev;
  608. dev->type = &dax_mapping_type;
  609. dev_set_name(dev, "mapping%d", mapping->id);
  610. rc = device_add(dev);
  611. if (rc) {
  612. put_device(dev);
  613. return rc;
  614. }
  615. rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_mapping,
  616. dev);
  617. if (rc)
  618. return rc;
  619. return 0;
  620. }
  621. static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
  622. resource_size_t size)
  623. {
  624. struct dax_region *dax_region = dev_dax->region;
  625. struct resource *res = &dax_region->res;
  626. struct device *dev = &dev_dax->dev;
  627. struct dev_dax_range *ranges;
  628. unsigned long pgoff = 0;
  629. struct resource *alloc;
  630. int i, rc;
  631. device_lock_assert(dax_region->dev);
  632. /* handle the seed alloc special case */
  633. if (!size) {
  634. if (dev_WARN_ONCE(dev, dev_dax->nr_range,
  635. "0-size allocation must be first\n"))
  636. return -EBUSY;
  637. /* nr_range == 0 is elsewhere special cased as 0-size device */
  638. return 0;
  639. }
  640. ranges = krealloc(dev_dax->ranges, sizeof(*ranges)
  641. * (dev_dax->nr_range + 1), GFP_KERNEL);
  642. if (!ranges)
  643. return -ENOMEM;
  644. alloc = __request_region(res, start, size, dev_name(dev), 0);
  645. if (!alloc) {
  646. /*
  647. * If this was an empty set of ranges nothing else
  648. * will release @ranges, so do it now.
  649. */
  650. if (!dev_dax->nr_range) {
  651. kfree(ranges);
  652. ranges = NULL;
  653. }
  654. dev_dax->ranges = ranges;
  655. return -ENOMEM;
  656. }
  657. for (i = 0; i < dev_dax->nr_range; i++)
  658. pgoff += PHYS_PFN(range_len(&ranges[i].range));
  659. dev_dax->ranges = ranges;
  660. ranges[dev_dax->nr_range++] = (struct dev_dax_range) {
  661. .pgoff = pgoff,
  662. .range = {
  663. .start = alloc->start,
  664. .end = alloc->end,
  665. },
  666. };
  667. dev_dbg(dev, "alloc range[%d]: %pa:%pa\n", dev_dax->nr_range - 1,
  668. &alloc->start, &alloc->end);
  669. /*
  670. * A dev_dax instance must be registered before mapping device
  671. * children can be added. Defer to devm_create_dev_dax() to add
  672. * the initial mapping device.
  673. */
  674. if (!device_is_registered(&dev_dax->dev))
  675. return 0;
  676. rc = devm_register_dax_mapping(dev_dax, dev_dax->nr_range - 1);
  677. if (rc)
  678. trim_dev_dax_range(dev_dax);
  679. return rc;
  680. }
  681. static int adjust_dev_dax_range(struct dev_dax *dev_dax, struct resource *res, resource_size_t size)
  682. {
  683. int last_range = dev_dax->nr_range - 1;
  684. struct dev_dax_range *dax_range = &dev_dax->ranges[last_range];
  685. struct dax_region *dax_region = dev_dax->region;
  686. bool is_shrink = resource_size(res) > size;
  687. struct range *range = &dax_range->range;
  688. struct device *dev = &dev_dax->dev;
  689. int rc;
  690. device_lock_assert(dax_region->dev);
  691. if (dev_WARN_ONCE(dev, !size, "deletion is handled by dev_dax_shrink\n"))
  692. return -EINVAL;
  693. rc = adjust_resource(res, range->start, size);
  694. if (rc)
  695. return rc;
  696. *range = (struct range) {
  697. .start = range->start,
  698. .end = range->start + size - 1,
  699. };
  700. dev_dbg(dev, "%s range[%d]: %#llx:%#llx\n", is_shrink ? "shrink" : "extend",
  701. last_range, (unsigned long long) range->start,
  702. (unsigned long long) range->end);
  703. return 0;
  704. }
  705. static ssize_t size_show(struct device *dev,
  706. struct device_attribute *attr, char *buf)
  707. {
  708. struct dev_dax *dev_dax = to_dev_dax(dev);
  709. unsigned long long size;
  710. device_lock(dev);
  711. size = dev_dax_size(dev_dax);
  712. device_unlock(dev);
  713. return sprintf(buf, "%llu\n", size);
  714. }
  715. static bool alloc_is_aligned(struct dev_dax *dev_dax, resource_size_t size)
  716. {
  717. /*
  718. * The minimum mapping granularity for a device instance is a
  719. * single subsection, unless the arch says otherwise.
  720. */
  721. return IS_ALIGNED(size, max_t(unsigned long, dev_dax->align, memremap_compat_align()));
  722. }
  723. static int dev_dax_shrink(struct dev_dax *dev_dax, resource_size_t size)
  724. {
  725. resource_size_t to_shrink = dev_dax_size(dev_dax) - size;
  726. struct dax_region *dax_region = dev_dax->region;
  727. struct device *dev = &dev_dax->dev;
  728. int i;
  729. for (i = dev_dax->nr_range - 1; i >= 0; i--) {
  730. struct range *range = &dev_dax->ranges[i].range;
  731. struct dax_mapping *mapping = dev_dax->ranges[i].mapping;
  732. struct resource *adjust = NULL, *res;
  733. resource_size_t shrink;
  734. shrink = min_t(u64, to_shrink, range_len(range));
  735. if (shrink >= range_len(range)) {
  736. devm_release_action(dax_region->dev,
  737. unregister_dax_mapping, &mapping->dev);
  738. trim_dev_dax_range(dev_dax);
  739. to_shrink -= shrink;
  740. if (!to_shrink)
  741. break;
  742. continue;
  743. }
  744. for_each_dax_region_resource(dax_region, res)
  745. if (strcmp(res->name, dev_name(dev)) == 0
  746. && res->start == range->start) {
  747. adjust = res;
  748. break;
  749. }
  750. if (dev_WARN_ONCE(dev, !adjust || i != dev_dax->nr_range - 1,
  751. "failed to find matching resource\n"))
  752. return -ENXIO;
  753. return adjust_dev_dax_range(dev_dax, adjust, range_len(range)
  754. - shrink);
  755. }
  756. return 0;
  757. }
  758. /*
  759. * Only allow adjustments that preserve the relative pgoff of existing
  760. * allocations. I.e. the dev_dax->ranges array is ordered by increasing pgoff.
  761. */
  762. static bool adjust_ok(struct dev_dax *dev_dax, struct resource *res)
  763. {
  764. struct dev_dax_range *last;
  765. int i;
  766. if (dev_dax->nr_range == 0)
  767. return false;
  768. if (strcmp(res->name, dev_name(&dev_dax->dev)) != 0)
  769. return false;
  770. last = &dev_dax->ranges[dev_dax->nr_range - 1];
  771. if (last->range.start != res->start || last->range.end != res->end)
  772. return false;
  773. for (i = 0; i < dev_dax->nr_range - 1; i++) {
  774. struct dev_dax_range *dax_range = &dev_dax->ranges[i];
  775. if (dax_range->pgoff > last->pgoff)
  776. return false;
  777. }
  778. return true;
  779. }
  780. static ssize_t dev_dax_resize(struct dax_region *dax_region,
  781. struct dev_dax *dev_dax, resource_size_t size)
  782. {
  783. resource_size_t avail = dax_region_avail_size(dax_region), to_alloc;
  784. resource_size_t dev_size = dev_dax_size(dev_dax);
  785. struct resource *region_res = &dax_region->res;
  786. struct device *dev = &dev_dax->dev;
  787. struct resource *res, *first;
  788. resource_size_t alloc = 0;
  789. int rc;
  790. if (dev->driver)
  791. return -EBUSY;
  792. if (size == dev_size)
  793. return 0;
  794. if (size > dev_size && size - dev_size > avail)
  795. return -ENOSPC;
  796. if (size < dev_size)
  797. return dev_dax_shrink(dev_dax, size);
  798. to_alloc = size - dev_size;
  799. if (dev_WARN_ONCE(dev, !alloc_is_aligned(dev_dax, to_alloc),
  800. "resize of %pa misaligned\n", &to_alloc))
  801. return -ENXIO;
  802. /*
  803. * Expand the device into the unused portion of the region. This
  804. * may involve adjusting the end of an existing resource, or
  805. * allocating a new resource.
  806. */
  807. retry:
  808. first = region_res->child;
  809. if (!first)
  810. return alloc_dev_dax_range(dev_dax, dax_region->res.start, to_alloc);
  811. rc = -ENOSPC;
  812. for (res = first; res; res = res->sibling) {
  813. struct resource *next = res->sibling;
  814. /* space at the beginning of the region */
  815. if (res == first && res->start > dax_region->res.start) {
  816. alloc = min(res->start - dax_region->res.start, to_alloc);
  817. rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, alloc);
  818. break;
  819. }
  820. alloc = 0;
  821. /* space between allocations */
  822. if (next && next->start > res->end + 1)
  823. alloc = min(next->start - (res->end + 1), to_alloc);
  824. /* space at the end of the region */
  825. if (!alloc && !next && res->end < region_res->end)
  826. alloc = min(region_res->end - res->end, to_alloc);
  827. if (!alloc)
  828. continue;
  829. if (adjust_ok(dev_dax, res)) {
  830. rc = adjust_dev_dax_range(dev_dax, res, resource_size(res) + alloc);
  831. break;
  832. }
  833. rc = alloc_dev_dax_range(dev_dax, res->end + 1, alloc);
  834. break;
  835. }
  836. if (rc)
  837. return rc;
  838. to_alloc -= alloc;
  839. if (to_alloc)
  840. goto retry;
  841. return 0;
  842. }
  843. static ssize_t size_store(struct device *dev, struct device_attribute *attr,
  844. const char *buf, size_t len)
  845. {
  846. ssize_t rc;
  847. unsigned long long val;
  848. struct dev_dax *dev_dax = to_dev_dax(dev);
  849. struct dax_region *dax_region = dev_dax->region;
  850. rc = kstrtoull(buf, 0, &val);
  851. if (rc)
  852. return rc;
  853. if (!alloc_is_aligned(dev_dax, val)) {
  854. dev_dbg(dev, "%s: size: %lld misaligned\n", __func__, val);
  855. return -EINVAL;
  856. }
  857. device_lock(dax_region->dev);
  858. if (!dax_region->dev->driver) {
  859. device_unlock(dax_region->dev);
  860. return -ENXIO;
  861. }
  862. device_lock(dev);
  863. rc = dev_dax_resize(dax_region, dev_dax, val);
  864. device_unlock(dev);
  865. device_unlock(dax_region->dev);
  866. return rc == 0 ? len : rc;
  867. }
  868. static DEVICE_ATTR_RW(size);
  869. static ssize_t range_parse(const char *opt, size_t len, struct range *range)
  870. {
  871. unsigned long long addr = 0;
  872. char *start, *end, *str;
  873. ssize_t rc = -EINVAL;
  874. str = kstrdup(opt, GFP_KERNEL);
  875. if (!str)
  876. return rc;
  877. end = str;
  878. start = strsep(&end, "-");
  879. if (!start || !end)
  880. goto err;
  881. rc = kstrtoull(start, 16, &addr);
  882. if (rc)
  883. goto err;
  884. range->start = addr;
  885. rc = kstrtoull(end, 16, &addr);
  886. if (rc)
  887. goto err;
  888. range->end = addr;
  889. err:
  890. kfree(str);
  891. return rc;
  892. }
  893. static ssize_t mapping_store(struct device *dev, struct device_attribute *attr,
  894. const char *buf, size_t len)
  895. {
  896. struct dev_dax *dev_dax = to_dev_dax(dev);
  897. struct dax_region *dax_region = dev_dax->region;
  898. size_t to_alloc;
  899. struct range r;
  900. ssize_t rc;
  901. rc = range_parse(buf, len, &r);
  902. if (rc)
  903. return rc;
  904. rc = -ENXIO;
  905. device_lock(dax_region->dev);
  906. if (!dax_region->dev->driver) {
  907. device_unlock(dax_region->dev);
  908. return rc;
  909. }
  910. device_lock(dev);
  911. to_alloc = range_len(&r);
  912. if (alloc_is_aligned(dev_dax, to_alloc))
  913. rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
  914. device_unlock(dev);
  915. device_unlock(dax_region->dev);
  916. return rc == 0 ? len : rc;
  917. }
  918. static DEVICE_ATTR_WO(mapping);
  919. static ssize_t align_show(struct device *dev,
  920. struct device_attribute *attr, char *buf)
  921. {
  922. struct dev_dax *dev_dax = to_dev_dax(dev);
  923. return sprintf(buf, "%d\n", dev_dax->align);
  924. }
  925. static ssize_t dev_dax_validate_align(struct dev_dax *dev_dax)
  926. {
  927. resource_size_t dev_size = dev_dax_size(dev_dax);
  928. struct device *dev = &dev_dax->dev;
  929. int i;
  930. if (dev_size > 0 && !alloc_is_aligned(dev_dax, dev_size)) {
  931. dev_dbg(dev, "%s: align %u invalid for size %pa\n",
  932. __func__, dev_dax->align, &dev_size);
  933. return -EINVAL;
  934. }
  935. for (i = 0; i < dev_dax->nr_range; i++) {
  936. size_t len = range_len(&dev_dax->ranges[i].range);
  937. if (!alloc_is_aligned(dev_dax, len)) {
  938. dev_dbg(dev, "%s: align %u invalid for range %d\n",
  939. __func__, dev_dax->align, i);
  940. return -EINVAL;
  941. }
  942. }
  943. return 0;
  944. }
  945. static ssize_t align_store(struct device *dev, struct device_attribute *attr,
  946. const char *buf, size_t len)
  947. {
  948. struct dev_dax *dev_dax = to_dev_dax(dev);
  949. struct dax_region *dax_region = dev_dax->region;
  950. unsigned long val, align_save;
  951. ssize_t rc;
  952. rc = kstrtoul(buf, 0, &val);
  953. if (rc)
  954. return -ENXIO;
  955. if (!dax_align_valid(val))
  956. return -EINVAL;
  957. device_lock(dax_region->dev);
  958. if (!dax_region->dev->driver) {
  959. device_unlock(dax_region->dev);
  960. return -ENXIO;
  961. }
  962. device_lock(dev);
  963. if (dev->driver) {
  964. rc = -EBUSY;
  965. goto out_unlock;
  966. }
  967. align_save = dev_dax->align;
  968. dev_dax->align = val;
  969. rc = dev_dax_validate_align(dev_dax);
  970. if (rc)
  971. dev_dax->align = align_save;
  972. out_unlock:
  973. device_unlock(dev);
  974. device_unlock(dax_region->dev);
  975. return rc == 0 ? len : rc;
  976. }
  977. static DEVICE_ATTR_RW(align);
  978. static int dev_dax_target_node(struct dev_dax *dev_dax)
  979. {
  980. struct dax_region *dax_region = dev_dax->region;
  981. return dax_region->target_node;
  982. }
  983. static ssize_t target_node_show(struct device *dev,
  984. struct device_attribute *attr, char *buf)
  985. {
  986. struct dev_dax *dev_dax = to_dev_dax(dev);
  987. return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
  988. }
  989. static DEVICE_ATTR_RO(target_node);
  990. static ssize_t resource_show(struct device *dev,
  991. struct device_attribute *attr, char *buf)
  992. {
  993. struct dev_dax *dev_dax = to_dev_dax(dev);
  994. struct dax_region *dax_region = dev_dax->region;
  995. unsigned long long start;
  996. if (dev_dax->nr_range < 1)
  997. start = dax_region->res.start;
  998. else
  999. start = dev_dax->ranges[0].range.start;
  1000. return sprintf(buf, "%#llx\n", start);
  1001. }
  1002. static DEVICE_ATTR(resource, 0400, resource_show, NULL);
  1003. static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
  1004. char *buf)
  1005. {
  1006. /*
  1007. * We only ever expect to handle device-dax instances, i.e. the
  1008. * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
  1009. */
  1010. return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
  1011. }
  1012. static DEVICE_ATTR_RO(modalias);
  1013. static ssize_t numa_node_show(struct device *dev,
  1014. struct device_attribute *attr, char *buf)
  1015. {
  1016. return sprintf(buf, "%d\n", dev_to_node(dev));
  1017. }
  1018. static DEVICE_ATTR_RO(numa_node);
  1019. static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
  1020. {
  1021. struct device *dev = container_of(kobj, struct device, kobj);
  1022. struct dev_dax *dev_dax = to_dev_dax(dev);
  1023. struct dax_region *dax_region = dev_dax->region;
  1024. if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
  1025. return 0;
  1026. if (a == &dev_attr_numa_node.attr && !IS_ENABLED(CONFIG_NUMA))
  1027. return 0;
  1028. if (a == &dev_attr_mapping.attr && is_static(dax_region))
  1029. return 0;
  1030. if ((a == &dev_attr_align.attr ||
  1031. a == &dev_attr_size.attr) && is_static(dax_region))
  1032. return 0444;
  1033. return a->mode;
  1034. }
  1035. static struct attribute *dev_dax_attributes[] = {
  1036. &dev_attr_modalias.attr,
  1037. &dev_attr_size.attr,
  1038. &dev_attr_mapping.attr,
  1039. &dev_attr_target_node.attr,
  1040. &dev_attr_align.attr,
  1041. &dev_attr_resource.attr,
  1042. &dev_attr_numa_node.attr,
  1043. NULL,
  1044. };
  1045. static const struct attribute_group dev_dax_attribute_group = {
  1046. .attrs = dev_dax_attributes,
  1047. .is_visible = dev_dax_visible,
  1048. };
  1049. static const struct attribute_group *dax_attribute_groups[] = {
  1050. &dev_dax_attribute_group,
  1051. NULL,
  1052. };
  1053. static void dev_dax_release(struct device *dev)
  1054. {
  1055. struct dev_dax *dev_dax = to_dev_dax(dev);
  1056. struct dax_region *dax_region = dev_dax->region;
  1057. struct dax_device *dax_dev = dev_dax->dax_dev;
  1058. put_dax(dax_dev);
  1059. free_dev_dax_id(dev_dax);
  1060. dax_region_put(dax_region);
  1061. kfree(dev_dax->pgmap);
  1062. kfree(dev_dax);
  1063. }
  1064. static const struct device_type dev_dax_type = {
  1065. .release = dev_dax_release,
  1066. .groups = dax_attribute_groups,
  1067. };
  1068. struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
  1069. {
  1070. struct dax_region *dax_region = data->dax_region;
  1071. struct device *parent = dax_region->dev;
  1072. struct dax_device *dax_dev;
  1073. struct dev_dax *dev_dax;
  1074. struct inode *inode;
  1075. struct device *dev;
  1076. int rc;
  1077. dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
  1078. if (!dev_dax)
  1079. return ERR_PTR(-ENOMEM);
  1080. if (is_static(dax_region)) {
  1081. if (dev_WARN_ONCE(parent, data->id < 0,
  1082. "dynamic id specified to static region\n")) {
  1083. rc = -EINVAL;
  1084. goto err_id;
  1085. }
  1086. dev_dax->id = data->id;
  1087. } else {
  1088. if (dev_WARN_ONCE(parent, data->id >= 0,
  1089. "static id specified to dynamic region\n")) {
  1090. rc = -EINVAL;
  1091. goto err_id;
  1092. }
  1093. rc = ida_alloc(&dax_region->ida, GFP_KERNEL);
  1094. if (rc < 0)
  1095. goto err_id;
  1096. dev_dax->id = rc;
  1097. }
  1098. dev_dax->region = dax_region;
  1099. dev = &dev_dax->dev;
  1100. device_initialize(dev);
  1101. dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id);
  1102. rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, data->size);
  1103. if (rc)
  1104. goto err_range;
  1105. if (data->pgmap) {
  1106. dev_WARN_ONCE(parent, !is_static(dax_region),
  1107. "custom dev_pagemap requires a static dax_region\n");
  1108. dev_dax->pgmap = kmemdup(data->pgmap,
  1109. sizeof(struct dev_pagemap), GFP_KERNEL);
  1110. if (!dev_dax->pgmap) {
  1111. rc = -ENOMEM;
  1112. goto err_pgmap;
  1113. }
  1114. }
  1115. /*
  1116. * No 'host' or dax_operations since there is no access to this
  1117. * device outside of mmap of the resulting character device.
  1118. */
  1119. dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
  1120. if (IS_ERR(dax_dev)) {
  1121. rc = PTR_ERR(dax_dev);
  1122. goto err_alloc_dax;
  1123. }
  1124. /* a device_dax instance is dead while the driver is not attached */
  1125. kill_dax(dax_dev);
  1126. dev_dax->dax_dev = dax_dev;
  1127. dev_dax->target_node = dax_region->target_node;
  1128. dev_dax->align = dax_region->align;
  1129. ida_init(&dev_dax->ida);
  1130. kref_get(&dax_region->kref);
  1131. inode = dax_inode(dax_dev);
  1132. dev->devt = inode->i_rdev;
  1133. if (data->subsys == DEV_DAX_BUS)
  1134. dev->bus = &dax_bus_type;
  1135. else
  1136. dev->class = dax_class;
  1137. dev->parent = parent;
  1138. dev->type = &dev_dax_type;
  1139. rc = device_add(dev);
  1140. if (rc) {
  1141. kill_dev_dax(dev_dax);
  1142. put_device(dev);
  1143. return ERR_PTR(rc);
  1144. }
  1145. rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
  1146. if (rc)
  1147. return ERR_PTR(rc);
  1148. /* register mapping device for the initial allocation range */
  1149. if (dev_dax->nr_range && range_len(&dev_dax->ranges[0].range)) {
  1150. rc = devm_register_dax_mapping(dev_dax, 0);
  1151. if (rc)
  1152. return ERR_PTR(rc);
  1153. }
  1154. return dev_dax;
  1155. err_alloc_dax:
  1156. kfree(dev_dax->pgmap);
  1157. err_pgmap:
  1158. free_dev_dax_ranges(dev_dax);
  1159. err_range:
  1160. free_dev_dax_id(dev_dax);
  1161. err_id:
  1162. kfree(dev_dax);
  1163. return ERR_PTR(rc);
  1164. }
  1165. EXPORT_SYMBOL_GPL(devm_create_dev_dax);
  1166. static int match_always_count;
  1167. int __dax_driver_register(struct dax_device_driver *dax_drv,
  1168. struct module *module, const char *mod_name)
  1169. {
  1170. struct device_driver *drv = &dax_drv->drv;
  1171. int rc = 0;
  1172. INIT_LIST_HEAD(&dax_drv->ids);
  1173. drv->owner = module;
  1174. drv->name = mod_name;
  1175. drv->mod_name = mod_name;
  1176. drv->bus = &dax_bus_type;
  1177. /* there can only be one default driver */
  1178. mutex_lock(&dax_bus_lock);
  1179. match_always_count += dax_drv->match_always;
  1180. if (match_always_count > 1) {
  1181. match_always_count--;
  1182. WARN_ON(1);
  1183. rc = -EINVAL;
  1184. }
  1185. mutex_unlock(&dax_bus_lock);
  1186. if (rc)
  1187. return rc;
  1188. return driver_register(drv);
  1189. }
  1190. EXPORT_SYMBOL_GPL(__dax_driver_register);
  1191. void dax_driver_unregister(struct dax_device_driver *dax_drv)
  1192. {
  1193. struct device_driver *drv = &dax_drv->drv;
  1194. struct dax_id *dax_id, *_id;
  1195. mutex_lock(&dax_bus_lock);
  1196. match_always_count -= dax_drv->match_always;
  1197. list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
  1198. list_del(&dax_id->list);
  1199. kfree(dax_id);
  1200. }
  1201. mutex_unlock(&dax_bus_lock);
  1202. driver_unregister(drv);
  1203. }
  1204. EXPORT_SYMBOL_GPL(dax_driver_unregister);
  1205. int __init dax_bus_init(void)
  1206. {
  1207. int rc;
  1208. if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
  1209. dax_class = class_create(THIS_MODULE, "dax");
  1210. if (IS_ERR(dax_class))
  1211. return PTR_ERR(dax_class);
  1212. }
  1213. rc = bus_register(&dax_bus_type);
  1214. if (rc)
  1215. class_destroy(dax_class);
  1216. return rc;
  1217. }
  1218. void __exit dax_bus_exit(void)
  1219. {
  1220. bus_unregister(&dax_bus_type);
  1221. class_destroy(dax_class);
  1222. }