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-private.h"
  23 #include "dax.h"
  24
  25 static struct class *dax_class;
  26
  27 /*
  28  * Rely on the fact that drvdata is set before the attributes are
  29  * registered, and that the attributes are unregistered before drvdata
  30  * is cleared to assume that drvdata is always valid.
  31  */
  32 static ssize_t id_show(struct device *dev,
  33                 struct device_attribute *attr, char *buf)
  34 {
  35         struct dax_region *dax_region = dev_get_drvdata(dev);
  36
  37         return sprintf(buf, "%d\n", dax_region->id);
  38 }
  39 static DEVICE_ATTR_RO(id);
  40
  41 static ssize_t region_size_show(struct device *dev,
  42                 struct device_attribute *attr, char *buf)
  43 {
  44         struct dax_region *dax_region = dev_get_drvdata(dev);
  45
  46         return sprintf(buf, "%llu\n", (unsigned long long)
  47                         resource_size(&dax_region->res));
  48 }
  49 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
  50                 region_size_show, NULL);
  51
  52 static ssize_t align_show(struct device *dev,
  53                 struct device_attribute *attr, char *buf)
  54 {
  55         struct dax_region *dax_region = dev_get_drvdata(dev);
  56
  57         return sprintf(buf, "%u\n", dax_region->align);
  58 }
  59 static DEVICE_ATTR_RO(align);
  60
  61 static struct attribute *dax_region_attributes[] = {
  62         &dev_attr_region_size.attr,
  63         &dev_attr_align.attr,
  64         &dev_attr_id.attr,
  65         NULL,
  66 };
  67
  68 static const struct attribute_group dax_region_attribute_group = {
  69         .name = "dax_region",
  70         .attrs = dax_region_attributes,
  71 };
  72
  73 static const struct attribute_group *dax_region_attribute_groups[] = {
  74         &dax_region_attribute_group,
  75         NULL,
  76 };
  77
  78 static void dax_region_free(struct kref *kref)
  79 {
  80         struct dax_region *dax_region;
  81
  82         dax_region = container_of(kref, struct dax_region, kref);
  83         kfree(dax_region);
  84 }
  85
  86 void dax_region_put(struct dax_region *dax_region)
  87 {
  88         kref_put(&dax_region->kref, dax_region_free);
  89 }
  90 EXPORT_SYMBOL_GPL(dax_region_put);
  91
  92 static void dax_region_unregister(void *region)
  93 {
  94         struct dax_region *dax_region = region;
  95
  96         sysfs_remove_groups(&dax_region->dev->kobj,
  97                         dax_region_attribute_groups);
  98         dax_region_put(dax_region);
  99 }
 100
 101 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 102                 struct resource *res, unsigned int align, void *addr,
 103                 unsigned long pfn_flags)
 104 {
 105         struct dax_region *dax_region;
 106
 107         /*
 108          * The DAX core assumes that it can store its private data in
 109          * parent->driver_data. This WARN is a reminder / safeguard for
 110          * developers of device-dax drivers.
 111          */
 112         if (dev_get_drvdata(parent)) {
 113                 dev_WARN(parent, "dax core failed to setup private data\n");
 114                 return NULL;
 115         }
 116
 117         if (!IS_ALIGNED(res->start, align)
 118                         || !IS_ALIGNED(resource_size(res), align))
 119                 return NULL;
 120
 121         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 122         if (!dax_region)
 123                 return NULL;
 124
 125         dev_set_drvdata(parent, dax_region);
 126         memcpy(&dax_region->res, res, sizeof(*res));
 127         dax_region->pfn_flags = pfn_flags;
 128         kref_init(&dax_region->kref);
 129         dax_region->id = region_id;
 130         ida_init(&dax_region->ida);
 131         dax_region->align = align;
 132         dax_region->dev = parent;
 133         dax_region->base = addr;
 134         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 135                 kfree(dax_region);
 136                 return NULL;
 137         }
 138
 139         kref_get(&dax_region->kref);
 140         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 141                 return NULL;
 142         return dax_region;
 143 }
 144 EXPORT_SYMBOL_GPL(alloc_dax_region);
 145
 146 static struct dev_dax *to_dev_dax(struct device *dev)
 147 {
 148         return container_of(dev, struct dev_dax, dev);
 149 }
 150
 151 static ssize_t size_show(struct device *dev,
 152                 struct device_attribute *attr, char *buf)
 153 {
 154         struct dev_dax *dev_dax = to_dev_dax(dev);
 155         unsigned long long size = 0;
 156         int i;
 157
 158         for (i = 0; i < dev_dax->num_resources; i++)
 159                 size += resource_size(&dev_dax->res[i]);
 160
 161         return sprintf(buf, "%llu\n", size);
 162 }
 163 static DEVICE_ATTR_RO(size);
 164
 165 static struct attribute *dev_dax_attributes[] = {
 166         &dev_attr_size.attr,
 167         NULL,
 168 };
 169
 170 static const struct attribute_group dev_dax_attribute_group = {
 171         .attrs = dev_dax_attributes,
 172 };
 173
 174 static const struct attribute_group *dax_attribute_groups[] = {
 175         &dev_dax_attribute_group,
 176         NULL,
 177 };
 178
 179 static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
 180                 const char *func)
 181 {
 182         struct dax_region *dax_region = dev_dax->region;
 183         struct device *dev = &dev_dax->dev;
 184         unsigned long mask;
 185
 186         if (!dax_alive(dev_dax->dax_dev))
 187                 return -ENXIO;
 188
 189         /* prevent private mappings from being established */
 190         if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
 191                 dev_info(dev, "%s: %s: fail, attempted private mapping\n",
 192                                 current->comm, func);
 193                 return -EINVAL;
 194         }
 195
 196         mask = dax_region->align - 1;
 197         if (vma->vm_start & mask || vma->vm_end & mask) {
 198                 dev_info(dev, "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
 199                                 current->comm, func, vma->vm_start, vma->vm_end,
 200                                 mask);
 201                 return -EINVAL;
 202         }
 203
 204         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
 205                         && (vma->vm_flags & VM_DONTCOPY) == 0) {
 206                 dev_info(dev, "%s: %s: fail, dax range requires MADV_DONTFORK\n",
 207                                 current->comm, func);
 208                 return -EINVAL;
 209         }
 210
 211         if (!vma_is_dax(vma)) {
 212                 dev_info(dev, "%s: %s: fail, vma is not DAX capable\n",
 213                                 current->comm, func);
 214                 return -EINVAL;
 215         }
 216
 217         return 0;
 218 }
 219
 220 /* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
 221 __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 222                 unsigned long size)
 223 {
 224         struct resource *res;
 225         /* gcc-4.6.3-nolibc for i386 complains that this is uninitialized */
 226         phys_addr_t uninitialized_var(phys);
 227         int i;
 228
 229         for (i = 0; i < dev_dax->num_resources; i++) {
 230                 res = &dev_dax->res[i];
 231                 phys = pgoff * PAGE_SIZE + res->start;
 232                 if (phys >= res->start && phys <= res->end)
 233                         break;
 234                 pgoff -= PHYS_PFN(resource_size(res));
 235         }
 236
 237         if (i < dev_dax->num_resources) {
 238                 res = &dev_dax->res[i];
 239                 if (phys + size - 1 <= res->end)
 240                         return phys;
 241         }
 242
 243         return -1;
 244 }
 245
 246 static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 247 {
 248         struct device *dev = &dev_dax->dev;
 249         struct dax_region *dax_region;
 250         int rc = VM_FAULT_SIGBUS;
 251         phys_addr_t phys;
 252         pfn_t pfn;
 253         unsigned int fault_size = PAGE_SIZE;
 254
 255         if (check_vma(dev_dax, vmf->vma, __func__))
 256                 return VM_FAULT_SIGBUS;
 257
 258         dax_region = dev_dax->region;
 259         if (dax_region->align > PAGE_SIZE) {
 260                 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 261                         dax_region->align, fault_size);
 262                 return VM_FAULT_SIGBUS;
 263         }
 264
 265         if (fault_size != dax_region->align)
 266                 return VM_FAULT_SIGBUS;
 267
 268         phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
 269         if (phys == -1) {
 270                 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", vmf->pgoff);
 271                 return VM_FAULT_SIGBUS;
 272         }
 273
 274         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 275
 276         rc = vm_insert_mixed(vmf->vma, vmf->address, pfn);
 277
 278         if (rc == -ENOMEM)
 279                 return VM_FAULT_OOM;
 280         if (rc < 0 && rc != -EBUSY)
 281                 return VM_FAULT_SIGBUS;
 282
 283         return VM_FAULT_NOPAGE;
 284 }
 285
 286 static int __dev_dax_pmd_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 287 {
 288         unsigned long pmd_addr = vmf->address & PMD_MASK;
 289         struct device *dev = &dev_dax->dev;
 290         struct dax_region *dax_region;
 291         phys_addr_t phys;
 292         pgoff_t pgoff;
 293         pfn_t pfn;
 294         unsigned int fault_size = PMD_SIZE;
 295
 296         if (check_vma(dev_dax, vmf->vma, __func__))
 297                 return VM_FAULT_SIGBUS;
 298
 299         dax_region = dev_dax->region;
 300         if (dax_region->align > PMD_SIZE) {
 301                 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 302                         dax_region->align, fault_size);
 303                 return VM_FAULT_SIGBUS;
 304         }
 305
 306         /* dax pmd mappings require pfn_t_devmap() */
 307         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 308                 dev_dbg(dev, "region lacks devmap flags\n");
 309                 return VM_FAULT_SIGBUS;
 310         }
 311
 312         if (fault_size < dax_region->align)
 313                 return VM_FAULT_SIGBUS;
 314         else if (fault_size > dax_region->align)
 315                 return VM_FAULT_FALLBACK;
 316
 317         /* if we are outside of the VMA */
 318         if (pmd_addr < vmf->vma->vm_start ||
 319                         (pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
 320                 return VM_FAULT_SIGBUS;
 321
 322         pgoff = linear_page_index(vmf->vma, pmd_addr);
 323         phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
 324         if (phys == -1) {
 325                 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 326                 return VM_FAULT_SIGBUS;
 327         }
 328
 329         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 330
 331         return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, pfn,
 332                         vmf->flags & FAULT_FLAG_WRITE);
 333 }
 334
 335 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 336 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 337 {
 338         unsigned long pud_addr = vmf->address & PUD_MASK;
 339         struct device *dev = &dev_dax->dev;
 340         struct dax_region *dax_region;
 341         phys_addr_t phys;
 342         pgoff_t pgoff;
 343         pfn_t pfn;
 344         unsigned int fault_size = PUD_SIZE;
 345
 346
 347         if (check_vma(dev_dax, vmf->vma, __func__))
 348                 return VM_FAULT_SIGBUS;
 349
 350         dax_region = dev_dax->region;
 351         if (dax_region->align > PUD_SIZE) {
 352                 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 353                         dax_region->align, fault_size);
 354                 return VM_FAULT_SIGBUS;
 355         }
 356
 357         /* dax pud mappings require pfn_t_devmap() */
 358         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 359                 dev_dbg(dev, "region lacks devmap flags\n");
 360                 return VM_FAULT_SIGBUS;
 361         }
 362
 363         if (fault_size < dax_region->align)
 364                 return VM_FAULT_SIGBUS;
 365         else if (fault_size > dax_region->align)
 366                 return VM_FAULT_FALLBACK;
 367
 368         /* if we are outside of the VMA */
 369         if (pud_addr < vmf->vma->vm_start ||
 370                         (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
 371                 return VM_FAULT_SIGBUS;
 372
 373         pgoff = linear_page_index(vmf->vma, pud_addr);
 374         phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
 375         if (phys == -1) {
 376                 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 377                 return VM_FAULT_SIGBUS;
 378         }
 379
 380         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 381
 382         return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, pfn,
 383                         vmf->flags & FAULT_FLAG_WRITE);
 384 }
 385 #else
 386 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 387 {
 388         return VM_FAULT_FALLBACK;
 389 }
 390 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 391
 392 static int dev_dax_huge_fault(struct vm_fault *vmf,
 393                 enum page_entry_size pe_size)
 394 {
 395         int rc, id;
 396         struct file *filp = vmf->vma->vm_file;
 397         struct dev_dax *dev_dax = filp->private_data;
 398
 399         dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
 400                         (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
 401                         vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 402
 403         id = dax_read_lock();
 404         switch (pe_size) {
 405         case PE_SIZE_PTE:
 406                 rc = __dev_dax_pte_fault(dev_dax, vmf);
 407                 break;
 408         case PE_SIZE_PMD:
 409                 rc = __dev_dax_pmd_fault(dev_dax, vmf);
 410                 break;
 411         case PE_SIZE_PUD:
 412                 rc = __dev_dax_pud_fault(dev_dax, vmf);
 413                 break;
 414         default:
 415                 rc = VM_FAULT_SIGBUS;
 416         }
 417         dax_read_unlock(id);
 418
 419         return rc;
 420 }
 421
 422 static int dev_dax_fault(struct vm_fault *vmf)
 423 {
 424         return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 425 }
 426
 427 static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
 428 {
 429         struct file *filp = vma->vm_file;
 430         struct dev_dax *dev_dax = filp->private_data;
 431         struct dax_region *dax_region = dev_dax->region;
 432
 433         if (!IS_ALIGNED(addr, dax_region->align))
 434                 return -EINVAL;
 435         return 0;
 436 }
 437
 438 static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
 439 {
 440         struct file *filp = vma->vm_file;
 441         struct dev_dax *dev_dax = filp->private_data;
 442         struct dax_region *dax_region = dev_dax->region;
 443
 444         return dax_region->align;
 445 }
 446
 447 static const struct vm_operations_struct dax_vm_ops = {
 448         .fault = dev_dax_fault,
 449         .huge_fault = dev_dax_huge_fault,
 450         .split = dev_dax_split,
 451         .pagesize = dev_dax_pagesize,
 452 };
 453
 454 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 455 {
 456         struct dev_dax *dev_dax = filp->private_data;
 457         int rc, id;
 458
 459         dev_dbg(&dev_dax->dev, "trace\n");
 460
 461         /*
 462          * We lock to check dax_dev liveness and will re-check at
 463          * fault time.
 464          */
 465         id = dax_read_lock();
 466         rc = check_vma(dev_dax, vma, __func__);
 467         dax_read_unlock(id);
 468         if (rc)
 469                 return rc;
 470
 471         vma->vm_ops = &dax_vm_ops;
 472         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 473         return 0;
 474 }
 475
 476 /* return an unmapped area aligned to the dax region specified alignment */
 477 static unsigned long dax_get_unmapped_area(struct file *filp,
 478                 unsigned long addr, unsigned long len, unsigned long pgoff,
 479                 unsigned long flags)
 480 {
 481         unsigned long off, off_end, off_align, len_align, addr_align, align;
 482         struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 483         struct dax_region *dax_region;
 484
 485         if (!dev_dax || addr)
 486                 goto out;
 487
 488         dax_region = dev_dax->region;
 489         align = dax_region->align;
 490         off = pgoff << PAGE_SHIFT;
 491         off_end = off + len;
 492         off_align = round_up(off, align);
 493
 494         if ((off_end <= off_align) || ((off_end - off_align) < align))
 495                 goto out;
 496
 497         len_align = len + align;
 498         if ((off + len_align) < off)
 499                 goto out;
 500
 501         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 502                         pgoff, flags);
 503         if (!IS_ERR_VALUE(addr_align)) {
 504                 addr_align += (off - addr_align) & (align - 1);
 505                 return addr_align;
 506         }
 507  out:
 508         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 509 }
 510
 511 static int dax_open(struct inode *inode, struct file *filp)
 512 {
 513         struct dax_device *dax_dev = inode_dax(inode);
 514         struct inode *__dax_inode = dax_inode(dax_dev);
 515         struct dev_dax *dev_dax = dax_get_private(dax_dev);
 516
 517         dev_dbg(&dev_dax->dev, "trace\n");
 518         inode->i_mapping = __dax_inode->i_mapping;
 519         inode->i_mapping->host = __dax_inode;
 520         filp->f_mapping = inode->i_mapping;
 521         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 522         filp->private_data = dev_dax;
 523         inode->i_flags = S_DAX;
 524
 525         return 0;
 526 }
 527
 528 static int dax_release(struct inode *inode, struct file *filp)
 529 {
 530         struct dev_dax *dev_dax = filp->private_data;
 531
 532         dev_dbg(&dev_dax->dev, "trace\n");
 533         return 0;
 534 }
 535
 536 static const struct file_operations dax_fops = {
 537         .llseek = noop_llseek,
 538         .owner = THIS_MODULE,
 539         .open = dax_open,
 540         .release = dax_release,
 541         .get_unmapped_area = dax_get_unmapped_area,
 542         .mmap = dax_mmap,
 543 };
 544
 545 static void dev_dax_release(struct device *dev)
 546 {
 547         struct dev_dax *dev_dax = to_dev_dax(dev);
 548         struct dax_region *dax_region = dev_dax->region;
 549         struct dax_device *dax_dev = dev_dax->dax_dev;
 550
 551         if (dev_dax->id >= 0)
 552                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 553         dax_region_put(dax_region);
 554         put_dax(dax_dev);
 555         kfree(dev_dax);
 556 }
 557
 558 static void kill_dev_dax(struct dev_dax *dev_dax)
 559 {
 560         struct dax_device *dax_dev = dev_dax->dax_dev;
 561         struct inode *inode = dax_inode(dax_dev);
 562
 563         kill_dax(dax_dev);
 564         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 565 }
 566
 567 static void unregister_dev_dax(void *dev)
 568 {
 569         struct dev_dax *dev_dax = to_dev_dax(dev);
 570         struct dax_device *dax_dev = dev_dax->dax_dev;
 571         struct inode *inode = dax_inode(dax_dev);
 572         struct cdev *cdev = inode->i_cdev;
 573
 574         dev_dbg(dev, "trace\n");
 575
 576         kill_dev_dax(dev_dax);
 577         cdev_device_del(cdev, dev);
 578         put_device(dev);
 579 }
 580
 581 struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
 582                 int id, struct resource *res, int count)
 583 {
 584         struct device *parent = dax_region->dev;
 585         struct dax_device *dax_dev;
 586         struct dev_dax *dev_dax;
 587         struct inode *inode;
 588         struct device *dev;
 589         struct cdev *cdev;
 590         int rc, i;
 591
 592         if (!count)
 593                 return ERR_PTR(-EINVAL);
 594
 595         dev_dax = kzalloc(sizeof(*dev_dax) + sizeof(*res) * count, GFP_KERNEL);
 596         if (!dev_dax)
 597                 return ERR_PTR(-ENOMEM);
 598
 599         for (i = 0; i < count; i++) {
 600                 if (!IS_ALIGNED(res[i].start, dax_region->align)
 601                                 || !IS_ALIGNED(resource_size(&res[i]),
 602                                         dax_region->align)) {
 603                         rc = -EINVAL;
 604                         break;
 605                 }
 606                 dev_dax->res[i].start = res[i].start;
 607                 dev_dax->res[i].end = res[i].end;
 608         }
 609
 610         if (i < count)
 611                 goto err_id;
 612
 613         if (id < 0) {
 614                 id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 615                 dev_dax->id = id;
 616                 if (id < 0) {
 617                         rc = id;
 618                         goto err_id;
 619                 }
 620         } else {
 621                 /* region provider owns @id lifetime */
 622                 dev_dax->id = -1;
 623         }
 624
 625         /*
 626          * No 'host' or dax_operations since there is no access to this
 627          * device outside of mmap of the resulting character device.
 628          */
 629         dax_dev = alloc_dax(dev_dax, NULL, NULL);
 630         if (!dax_dev) {
 631                 rc = -ENOMEM;
 632                 goto err_dax;
 633         }
 634
 635         /* from here on we're committed to teardown via dax_dev_release() */
 636         dev = &dev_dax->dev;
 637         device_initialize(dev);
 638
 639         inode = dax_inode(dax_dev);
 640         cdev = inode->i_cdev;
 641         cdev_init(cdev, &dax_fops);
 642         cdev->owner = parent->driver->owner;
 643
 644         dev_dax->num_resources = count;
 645         dev_dax->dax_dev = dax_dev;
 646         dev_dax->region = dax_region;
 647         kref_get(&dax_region->kref);
 648
 649         dev->devt = inode->i_rdev;
 650         dev->class = dax_class;
 651         dev->parent = parent;
 652         dev->groups = dax_attribute_groups;
 653         dev->release = dev_dax_release;
 654         dev_set_name(dev, "dax%d.%d", dax_region->id, id);
 655
 656         rc = cdev_device_add(cdev, dev);
 657         if (rc) {
 658                 kill_dev_dax(dev_dax);
 659                 put_device(dev);
 660                 return ERR_PTR(rc);
 661         }
 662
 663         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 664         if (rc)
 665                 return ERR_PTR(rc);
 666
 667         return dev_dax;
 668
 669  err_dax:
 670         if (dev_dax->id >= 0)
 671                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 672  err_id:
 673         kfree(dev_dax);
 674
 675         return ERR_PTR(rc);
 676 }
 677 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
 678
 679 static int __init dax_init(void)
 680 {
 681         dax_class = class_create(THIS_MODULE, "dax");
 682         return PTR_ERR_OR_ZERO(dax_class);
 683 }
 684
 685 static void __exit dax_exit(void)
 686 {
 687         class_destroy(dax_class);
 688 }
 689
 690 MODULE_AUTHOR("Intel Corporation");
 691 MODULE_LICENSE("GPL v2");
 692 subsys_initcall(dax_init);
 693 module_exit(dax_exit);