drivers/dax/device.c

   1 /*
   2  * Copyright(c) 2016 - 2017 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 #include <linux/pagemap.h>
  14 #include <linux/module.h>
  15 #include <linux/device.h>
  16 #include <linux/pfn_t.h>
  17 #include <linux/cdev.h>
  18 #include <linux/slab.h>
  19 #include <linux/dax.h>
  20 #include <linux/fs.h>
  21 #include <linux/mm.h>
  22 #include "dax.h"
  23
  24 static struct class *dax_class;
  25
  26 /**
  27  * struct dax_region - mapping infrastructure for dax devices
  28  * @id: kernel-wide unique region for a memory range
  29  * @base: linear address corresponding to @res
  30  * @kref: to pin while other agents have a need to do lookups
  31  * @dev: parent device backing this region
  32  * @align: allocation and mapping alignment for child dax devices
  33  * @res: physical address range of the region
  34  * @pfn_flags: identify whether the pfns are paged back or not
  35  */
  36 struct dax_region {
  37         int id;
  38         struct ida ida;
  39         void *base;
  40         struct kref kref;
  41         struct device *dev;
  42         unsigned int align;
  43         struct resource res;
  44         unsigned long pfn_flags;
  45 };
  46
  47 /**
  48  * struct dev_dax - instance data for a subdivision of a dax region
  49  * @region - parent region
  50  * @dax_dev - core dax functionality
  51  * @dev - device core
  52  * @id - child id in the region
  53  * @num_resources - number of physical address extents in this device
  54  * @res - array of physical address ranges
  55  */
  56 struct dev_dax {
  57         struct dax_region *region;
  58         struct dax_device *dax_dev;
  59         struct device dev;
  60         int id;
  61         int num_resources;
  62         struct resource res[0];
  63 };
  64
  65 static ssize_t id_show(struct device *dev,
  66                 struct device_attribute *attr, char *buf)
  67 {
  68         struct dax_region *dax_region;
  69         ssize_t rc = -ENXIO;
  70
  71         device_lock(dev);
  72         dax_region = dev_get_drvdata(dev);
  73         if (dax_region)
  74                 rc = sprintf(buf, "%d\n", dax_region->id);
  75         device_unlock(dev);
  76
  77         return rc;
  78 }
  79 static DEVICE_ATTR_RO(id);
  80
  81 static ssize_t region_size_show(struct device *dev,
  82                 struct device_attribute *attr, char *buf)
  83 {
  84         struct dax_region *dax_region;
  85         ssize_t rc = -ENXIO;
  86
  87         device_lock(dev);
  88         dax_region = dev_get_drvdata(dev);
  89         if (dax_region)
  90                 rc = sprintf(buf, "%llu\n", (unsigned long long)
  91                                 resource_size(&dax_region->res));
  92         device_unlock(dev);
  93
  94         return rc;
  95 }
  96 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
  97                 region_size_show, NULL);
  98
  99 static ssize_t align_show(struct device *dev,
 100                 struct device_attribute *attr, char *buf)
 101 {
 102         struct dax_region *dax_region;
 103         ssize_t rc = -ENXIO;
 104
 105         device_lock(dev);
 106         dax_region = dev_get_drvdata(dev);
 107         if (dax_region)
 108                 rc = sprintf(buf, "%u\n", dax_region->align);
 109         device_unlock(dev);
 110
 111         return rc;
 112 }
 113 static DEVICE_ATTR_RO(align);
 114
 115 static struct attribute *dax_region_attributes[] = {
 116         &dev_attr_region_size.attr,
 117         &dev_attr_align.attr,
 118         &dev_attr_id.attr,
 119         NULL,
 120 };
 121
 122 static const struct attribute_group dax_region_attribute_group = {
 123         .name = "dax_region",
 124         .attrs = dax_region_attributes,
 125 };
 126
 127 static const struct attribute_group *dax_region_attribute_groups[] = {
 128         &dax_region_attribute_group,
 129         NULL,
 130 };
 131
 132 static void dax_region_free(struct kref *kref)
 133 {
 134         struct dax_region *dax_region;
 135
 136         dax_region = container_of(kref, struct dax_region, kref);
 137         kfree(dax_region);
 138 }
 139
 140 void dax_region_put(struct dax_region *dax_region)
 141 {
 142         kref_put(&dax_region->kref, dax_region_free);
 143 }
 144 EXPORT_SYMBOL_GPL(dax_region_put);
 145
 146 static void dax_region_unregister(void *region)
 147 {
 148         struct dax_region *dax_region = region;
 149
 150         sysfs_remove_groups(&dax_region->dev->kobj,
 151                         dax_region_attribute_groups);
 152         dax_region_put(dax_region);
 153 }
 154
 155 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 156                 struct resource *res, unsigned int align, void *addr,
 157                 unsigned long pfn_flags)
 158 {
 159         struct dax_region *dax_region;
 160
 161         /*
 162          * The DAX core assumes that it can store its private data in
 163          * parent->driver_data. This WARN is a reminder / safeguard for
 164          * developers of device-dax drivers.
 165          */
 166         if (dev_get_drvdata(parent)) {
 167                 dev_WARN(parent, "dax core failed to setup private data\n");
 168                 return NULL;
 169         }
 170
 171         if (!IS_ALIGNED(res->start, align)
 172                         || !IS_ALIGNED(resource_size(res), align))
 173                 return NULL;
 174
 175         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 176         if (!dax_region)
 177                 return NULL;
 178
 179         dev_set_drvdata(parent, dax_region);
 180         memcpy(&dax_region->res, res, sizeof(*res));
 181         dax_region->pfn_flags = pfn_flags;
 182         kref_init(&dax_region->kref);
 183         dax_region->id = region_id;
 184         ida_init(&dax_region->ida);
 185         dax_region->align = align;
 186         dax_region->dev = parent;
 187         dax_region->base = addr;
 188         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 189                 kfree(dax_region);
 190                 return NULL;;
 191         }
 192
 193         kref_get(&dax_region->kref);
 194         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 195                 return NULL;
 196         return dax_region;
 197 }
 198 EXPORT_SYMBOL_GPL(alloc_dax_region);
 199
 200 static struct dev_dax *to_dev_dax(struct device *dev)
 201 {
 202         return container_of(dev, struct dev_dax, dev);
 203 }
 204
 205 static ssize_t size_show(struct device *dev,
 206                 struct device_attribute *attr, char *buf)
 207 {
 208         struct dev_dax *dev_dax = to_dev_dax(dev);
 209         unsigned long long size = 0;
 210         int i;
 211
 212         for (i = 0; i < dev_dax->num_resources; i++)
 213                 size += resource_size(&dev_dax->res[i]);
 214
 215         return sprintf(buf, "%llu\n", size);
 216 }
 217 static DEVICE_ATTR_RO(size);
 218
 219 static struct attribute *dev_dax_attributes[] = {
 220         &dev_attr_size.attr,
 221         NULL,
 222 };
 223
 224 static const struct attribute_group dev_dax_attribute_group = {
 225         .attrs = dev_dax_attributes,
 226 };
 227
 228 static const struct attribute_group *dax_attribute_groups[] = {
 229         &dev_dax_attribute_group,
 230         NULL,
 231 };
 232
 233 static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
 234                 const char *func)
 235 {
 236         struct dax_region *dax_region = dev_dax->region;
 237         struct device *dev = &dev_dax->dev;
 238         unsigned long mask;
 239
 240         if (!dax_alive(dev_dax->dax_dev))
 241                 return -ENXIO;
 242
 243         /* prevent private mappings from being established */
 244         if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
 245                 dev_info(dev, "%s: %s: fail, attempted private mapping\n",
 246                                 current->comm, func);
 247                 return -EINVAL;
 248         }
 249
 250         mask = dax_region->align - 1;
 251         if (vma->vm_start & mask || vma->vm_end & mask) {
 252                 dev_info(dev, "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
 253                                 current->comm, func, vma->vm_start, vma->vm_end,
 254                                 mask);
 255                 return -EINVAL;
 256         }
 257
 258         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
 259                         && (vma->vm_flags & VM_DONTCOPY) == 0) {
 260                 dev_info(dev, "%s: %s: fail, dax range requires MADV_DONTFORK\n",
 261                                 current->comm, func);
 262                 return -EINVAL;
 263         }
 264
 265         if (!vma_is_dax(vma)) {
 266                 dev_info(dev, "%s: %s: fail, vma is not DAX capable\n",
 267                                 current->comm, func);
 268                 return -EINVAL;
 269         }
 270
 271         return 0;
 272 }
 273
 274 static phys_addr_t pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 275                 unsigned long size)
 276 {
 277         struct resource *res;
 278         phys_addr_t phys;
 279         int i;
 280
 281         for (i = 0; i < dev_dax->num_resources; i++) {
 282                 res = &dev_dax->res[i];
 283                 phys = pgoff * PAGE_SIZE + res->start;
 284                 if (phys >= res->start && phys <= res->end)
 285                         break;
 286                 pgoff -= PHYS_PFN(resource_size(res));
 287         }
 288
 289         if (i < dev_dax->num_resources) {
 290                 res = &dev_dax->res[i];
 291                 if (phys + size - 1 <= res->end)
 292                         return phys;
 293         }
 294
 295         return -1;
 296 }
 297
 298 static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 299 {
 300         struct device *dev = &dev_dax->dev;
 301         struct dax_region *dax_region;
 302         int rc = VM_FAULT_SIGBUS;
 303         phys_addr_t phys;
 304         pfn_t pfn;
 305         unsigned int fault_size = PAGE_SIZE;
 306
 307         if (check_vma(dev_dax, vmf->vma, __func__))
 308                 return VM_FAULT_SIGBUS;
 309
 310         dax_region = dev_dax->region;
 311         if (dax_region->align > PAGE_SIZE) {
 312                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 313                         __func__, dax_region->align, fault_size);
 314                 return VM_FAULT_SIGBUS;
 315         }
 316
 317         if (fault_size != dax_region->align)
 318                 return VM_FAULT_SIGBUS;
 319
 320         phys = pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
 321         if (phys == -1) {
 322                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 323                                 vmf->pgoff);
 324                 return VM_FAULT_SIGBUS;
 325         }
 326
 327         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 328
 329         rc = vm_insert_mixed(vmf->vma, vmf->address, pfn);
 330
 331         if (rc == -ENOMEM)
 332                 return VM_FAULT_OOM;
 333         if (rc < 0 && rc != -EBUSY)
 334                 return VM_FAULT_SIGBUS;
 335
 336         return VM_FAULT_NOPAGE;
 337 }
 338
 339 static int __dev_dax_pmd_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 340 {
 341         unsigned long pmd_addr = vmf->address & PMD_MASK;
 342         struct device *dev = &dev_dax->dev;
 343         struct dax_region *dax_region;
 344         phys_addr_t phys;
 345         pgoff_t pgoff;
 346         pfn_t pfn;
 347         unsigned int fault_size = PMD_SIZE;
 348
 349         if (check_vma(dev_dax, vmf->vma, __func__))
 350                 return VM_FAULT_SIGBUS;
 351
 352         dax_region = dev_dax->region;
 353         if (dax_region->align > PMD_SIZE) {
 354                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 355                         __func__, dax_region->align, fault_size);
 356                 return VM_FAULT_SIGBUS;
 357         }
 358
 359         /* dax pmd mappings require pfn_t_devmap() */
 360         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 361                 dev_dbg(dev, "%s: region lacks devmap flags\n", __func__);
 362                 return VM_FAULT_SIGBUS;
 363         }
 364
 365         if (fault_size < dax_region->align)
 366                 return VM_FAULT_SIGBUS;
 367         else if (fault_size > dax_region->align)
 368                 return VM_FAULT_FALLBACK;
 369
 370         /* if we are outside of the VMA */
 371         if (pmd_addr < vmf->vma->vm_start ||
 372                         (pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
 373                 return VM_FAULT_SIGBUS;
 374
 375         pgoff = linear_page_index(vmf->vma, pmd_addr);
 376         phys = pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
 377         if (phys == -1) {
 378                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 379                                 pgoff);
 380                 return VM_FAULT_SIGBUS;
 381         }
 382
 383         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 384
 385         return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, pfn,
 386                         vmf->flags & FAULT_FLAG_WRITE);
 387 }
 388
 389 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 390 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 391 {
 392         unsigned long pud_addr = vmf->address & PUD_MASK;
 393         struct device *dev = &dev_dax->dev;
 394         struct dax_region *dax_region;
 395         phys_addr_t phys;
 396         pgoff_t pgoff;
 397         pfn_t pfn;
 398         unsigned int fault_size = PUD_SIZE;
 399
 400
 401         if (check_vma(dev_dax, vmf->vma, __func__))
 402                 return VM_FAULT_SIGBUS;
 403
 404         dax_region = dev_dax->region;
 405         if (dax_region->align > PUD_SIZE) {
 406                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 407                         __func__, dax_region->align, fault_size);
 408                 return VM_FAULT_SIGBUS;
 409         }
 410
 411         /* dax pud mappings require pfn_t_devmap() */
 412         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 413                 dev_dbg(dev, "%s: region lacks devmap flags\n", __func__);
 414                 return VM_FAULT_SIGBUS;
 415         }
 416
 417         if (fault_size < dax_region->align)
 418                 return VM_FAULT_SIGBUS;
 419         else if (fault_size > dax_region->align)
 420                 return VM_FAULT_FALLBACK;
 421
 422         /* if we are outside of the VMA */
 423         if (pud_addr < vmf->vma->vm_start ||
 424                         (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
 425                 return VM_FAULT_SIGBUS;
 426
 427         pgoff = linear_page_index(vmf->vma, pud_addr);
 428         phys = pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
 429         if (phys == -1) {
 430                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 431                                 pgoff);
 432                 return VM_FAULT_SIGBUS;
 433         }
 434
 435         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 436
 437         return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, pfn,
 438                         vmf->flags & FAULT_FLAG_WRITE);
 439 }
 440 #else
 441 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 442 {
 443         return VM_FAULT_FALLBACK;
 444 }
 445 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 446
 447 static int dev_dax_huge_fault(struct vm_fault *vmf,
 448                 enum page_entry_size pe_size)
 449 {
 450         int rc, id;
 451         struct file *filp = vmf->vma->vm_file;
 452         struct dev_dax *dev_dax = filp->private_data;
 453
 454         dev_dbg(&dev_dax->dev, "%s: %s: %s (%#lx - %#lx) size = %d\n", __func__,
 455                         current->comm, (vmf->flags & FAULT_FLAG_WRITE)
 456                         ? "write" : "read",
 457                         vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 458
 459         id = dax_read_lock();
 460         switch (pe_size) {
 461         case PE_SIZE_PTE:
 462                 rc = __dev_dax_pte_fault(dev_dax, vmf);
 463                 break;
 464         case PE_SIZE_PMD:
 465                 rc = __dev_dax_pmd_fault(dev_dax, vmf);
 466                 break;
 467         case PE_SIZE_PUD:
 468                 rc = __dev_dax_pud_fault(dev_dax, vmf);
 469                 break;
 470         default:
 471                 rc = VM_FAULT_SIGBUS;
 472         }
 473         dax_read_unlock(id);
 474
 475         return rc;
 476 }
 477
 478 static int dev_dax_fault(struct vm_fault *vmf)
 479 {
 480         return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 481 }
 482
 483 static const struct vm_operations_struct dax_vm_ops = {
 484         .fault = dev_dax_fault,
 485         .huge_fault = dev_dax_huge_fault,
 486 };
 487
 488 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 489 {
 490         struct dev_dax *dev_dax = filp->private_data;
 491         int rc, id;
 492
 493         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 494
 495         /*
 496          * We lock to check dax_dev liveness and will re-check at
 497          * fault time.
 498          */
 499         id = dax_read_lock();
 500         rc = check_vma(dev_dax, vma, __func__);
 501         dax_read_unlock(id);
 502         if (rc)
 503                 return rc;
 504
 505         vma->vm_ops = &dax_vm_ops;
 506         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 507         return 0;
 508 }
 509
 510 /* return an unmapped area aligned to the dax region specified alignment */
 511 static unsigned long dax_get_unmapped_area(struct file *filp,
 512                 unsigned long addr, unsigned long len, unsigned long pgoff,
 513                 unsigned long flags)
 514 {
 515         unsigned long off, off_end, off_align, len_align, addr_align, align;
 516         struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 517         struct dax_region *dax_region;
 518
 519         if (!dev_dax || addr)
 520                 goto out;
 521
 522         dax_region = dev_dax->region;
 523         align = dax_region->align;
 524         off = pgoff << PAGE_SHIFT;
 525         off_end = off + len;
 526         off_align = round_up(off, align);
 527
 528         if ((off_end <= off_align) || ((off_end - off_align) < align))
 529                 goto out;
 530
 531         len_align = len + align;
 532         if ((off + len_align) < off)
 533                 goto out;
 534
 535         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 536                         pgoff, flags);
 537         if (!IS_ERR_VALUE(addr_align)) {
 538                 addr_align += (off - addr_align) & (align - 1);
 539                 return addr_align;
 540         }
 541  out:
 542         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 543 }
 544
 545 static int dax_open(struct inode *inode, struct file *filp)
 546 {
 547         struct dax_device *dax_dev = inode_dax(inode);
 548         struct inode *__dax_inode = dax_inode(dax_dev);
 549         struct dev_dax *dev_dax = dax_get_private(dax_dev);
 550
 551         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 552         inode->i_mapping = __dax_inode->i_mapping;
 553         inode->i_mapping->host = __dax_inode;
 554         filp->f_mapping = inode->i_mapping;
 555         filp->private_data = dev_dax;
 556         inode->i_flags = S_DAX;
 557
 558         return 0;
 559 }
 560
 561 static int dax_release(struct inode *inode, struct file *filp)
 562 {
 563         struct dev_dax *dev_dax = filp->private_data;
 564
 565         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 566         return 0;
 567 }
 568
 569 static const struct file_operations dax_fops = {
 570         .llseek = noop_llseek,
 571         .owner = THIS_MODULE,
 572         .open = dax_open,
 573         .release = dax_release,
 574         .get_unmapped_area = dax_get_unmapped_area,
 575         .mmap = dax_mmap,
 576 };
 577
 578 static void dev_dax_release(struct device *dev)
 579 {
 580         struct dev_dax *dev_dax = to_dev_dax(dev);
 581         struct dax_region *dax_region = dev_dax->region;
 582         struct dax_device *dax_dev = dev_dax->dax_dev;
 583
 584         ida_simple_remove(&dax_region->ida, dev_dax->id);
 585         dax_region_put(dax_region);
 586         put_dax(dax_dev);
 587         kfree(dev_dax);
 588 }
 589
 590 static void kill_dev_dax(struct dev_dax *dev_dax)
 591 {
 592         struct dax_device *dax_dev = dev_dax->dax_dev;
 593         struct inode *inode = dax_inode(dax_dev);
 594
 595         kill_dax(dax_dev);
 596         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 597 }
 598
 599 static void unregister_dev_dax(void *dev)
 600 {
 601         struct dev_dax *dev_dax = to_dev_dax(dev);
 602         struct dax_device *dax_dev = dev_dax->dax_dev;
 603         struct inode *inode = dax_inode(dax_dev);
 604         struct cdev *cdev = inode->i_cdev;
 605
 606         dev_dbg(dev, "%s\n", __func__);
 607
 608         kill_dev_dax(dev_dax);
 609         cdev_device_del(cdev, dev);
 610         put_device(dev);
 611 }
 612
 613 struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
 614                 struct resource *res, int count)
 615 {
 616         struct device *parent = dax_region->dev;
 617         struct dax_device *dax_dev;
 618         struct dev_dax *dev_dax;
 619         struct inode *inode;
 620         struct device *dev;
 621         struct cdev *cdev;
 622         int rc = 0, i;
 623
 624         dev_dax = kzalloc(sizeof(*dev_dax) + sizeof(*res) * count, GFP_KERNEL);
 625         if (!dev_dax)
 626                 return ERR_PTR(-ENOMEM);
 627
 628         for (i = 0; i < count; i++) {
 629                 if (!IS_ALIGNED(res[i].start, dax_region->align)
 630                                 || !IS_ALIGNED(resource_size(&res[i]),
 631                                         dax_region->align)) {
 632                         rc = -EINVAL;
 633                         break;
 634                 }
 635                 dev_dax->res[i].start = res[i].start;
 636                 dev_dax->res[i].end = res[i].end;
 637         }
 638
 639         if (i < count)
 640                 goto err_id;
 641
 642         dev_dax->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 643         if (dev_dax->id < 0) {
 644                 rc = dev_dax->id;
 645                 goto err_id;
 646         }
 647
 648         dax_dev = alloc_dax(dev_dax, NULL);
 649         if (!dax_dev)
 650                 goto err_dax;
 651
 652         /* from here on we're committed to teardown via dax_dev_release() */
 653         dev = &dev_dax->dev;
 654         device_initialize(dev);
 655
 656         inode = dax_inode(dax_dev);
 657         cdev = inode->i_cdev;
 658         cdev_init(cdev, &dax_fops);
 659         cdev->owner = parent->driver->owner;
 660
 661         dev_dax->num_resources = count;
 662         dev_dax->dax_dev = dax_dev;
 663         dev_dax->region = dax_region;
 664         kref_get(&dax_region->kref);
 665
 666         dev->devt = inode->i_rdev;
 667         dev->class = dax_class;
 668         dev->parent = parent;
 669         dev->groups = dax_attribute_groups;
 670         dev->release = dev_dax_release;
 671         dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id);
 672
 673         rc = cdev_device_add(cdev, dev);
 674         if (rc) {
 675                 kill_dev_dax(dev_dax);
 676                 put_device(dev);
 677                 return ERR_PTR(rc);
 678         }
 679
 680         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 681         if (rc)
 682                 return ERR_PTR(rc);
 683
 684         return dev_dax;
 685
 686  err_dax:
 687         ida_simple_remove(&dax_region->ida, dev_dax->id);
 688  err_id:
 689         kfree(dev_dax);
 690
 691         return ERR_PTR(rc);
 692 }
 693 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
 694
 695 static int __init dax_init(void)
 696 {
 697         dax_class = class_create(THIS_MODULE, "dax");
 698         return PTR_ERR_OR_ZERO(dax_class);
 699 }
 700
 701 static void __exit dax_exit(void)
 702 {
 703         class_destroy(dax_class);
 704 }
 705
 706 MODULE_AUTHOR("Intel Corporation");
 707 MODULE_LICENSE("GPL v2");
 708 subsys_initcall(dax_init);
 709 module_exit(dax_exit);