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_ratelimited(dev,
 192                                 "%s: %s: fail, attempted private mapping\n",
 193                                 current->comm, func);
 194                 return -EINVAL;
 195         }
 196
 197         mask = dax_region->align - 1;
 198         if (vma->vm_start & mask || vma->vm_end & mask) {
 199                 dev_info_ratelimited(dev,
 200                                 "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
 201                                 current->comm, func, vma->vm_start, vma->vm_end,
 202                                 mask);
 203                 return -EINVAL;
 204         }
 205
 206         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
 207                         && (vma->vm_flags & VM_DONTCOPY) == 0) {
 208                 dev_info_ratelimited(dev,
 209                                 "%s: %s: fail, dax range requires MADV_DONTFORK\n",
 210                                 current->comm, func);
 211                 return -EINVAL;
 212         }
 213
 214         if (!vma_is_dax(vma)) {
 215                 dev_info_ratelimited(dev,
 216                                 "%s: %s: fail, vma is not DAX capable\n",
 217                                 current->comm, func);
 218                 return -EINVAL;
 219         }
 220
 221         return 0;
 222 }
 223
 224 /* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
 225 __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 226                 unsigned long size)
 227 {
 228         struct resource *res;
 229         /* gcc-4.6.3-nolibc for i386 complains that this is uninitialized */
 230         phys_addr_t uninitialized_var(phys);
 231         int i;
 232
 233         for (i = 0; i < dev_dax->num_resources; i++) {
 234                 res = &dev_dax->res[i];
 235                 phys = pgoff * PAGE_SIZE + res->start;
 236                 if (phys >= res->start && phys <= res->end)
 237                         break;
 238                 pgoff -= PHYS_PFN(resource_size(res));
 239         }
 240
 241         if (i < dev_dax->num_resources) {
 242                 res = &dev_dax->res[i];
 243                 if (phys + size - 1 <= res->end)
 244                         return phys;
 245         }
 246
 247         return -1;
 248 }
 249
 250 static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 251 {
 252         struct device *dev = &dev_dax->dev;
 253         struct dax_region *dax_region;
 254         int rc = VM_FAULT_SIGBUS;
 255         phys_addr_t phys;
 256         pfn_t pfn;
 257         unsigned int fault_size = PAGE_SIZE;
 258
 259         if (check_vma(dev_dax, vmf->vma, __func__))
 260                 return VM_FAULT_SIGBUS;
 261
 262         dax_region = dev_dax->region;
 263         if (dax_region->align > PAGE_SIZE) {
 264                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 265                         __func__, dax_region->align, fault_size);
 266                 return VM_FAULT_SIGBUS;
 267         }
 268
 269         if (fault_size != dax_region->align)
 270                 return VM_FAULT_SIGBUS;
 271
 272         phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
 273         if (phys == -1) {
 274                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 275                                 vmf->pgoff);
 276                 return VM_FAULT_SIGBUS;
 277         }
 278
 279         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 280
 281         rc = vm_insert_mixed(vmf->vma, vmf->address, pfn);
 282
 283         if (rc == -ENOMEM)
 284                 return VM_FAULT_OOM;
 285         if (rc < 0 && rc != -EBUSY)
 286                 return VM_FAULT_SIGBUS;
 287
 288         return VM_FAULT_NOPAGE;
 289 }
 290
 291 static int __dev_dax_pmd_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 292 {
 293         unsigned long pmd_addr = vmf->address & PMD_MASK;
 294         struct device *dev = &dev_dax->dev;
 295         struct dax_region *dax_region;
 296         phys_addr_t phys;
 297         pgoff_t pgoff;
 298         pfn_t pfn;
 299         unsigned int fault_size = PMD_SIZE;
 300
 301         if (check_vma(dev_dax, vmf->vma, __func__))
 302                 return VM_FAULT_SIGBUS;
 303
 304         dax_region = dev_dax->region;
 305         if (dax_region->align > PMD_SIZE) {
 306                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 307                         __func__, dax_region->align, fault_size);
 308                 return VM_FAULT_SIGBUS;
 309         }
 310
 311         /* dax pmd mappings require pfn_t_devmap() */
 312         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 313                 dev_dbg(dev, "%s: region lacks devmap flags\n", __func__);
 314                 return VM_FAULT_SIGBUS;
 315         }
 316
 317         if (fault_size < dax_region->align)
 318                 return VM_FAULT_SIGBUS;
 319         else if (fault_size > dax_region->align)
 320                 return VM_FAULT_FALLBACK;
 321
 322         /* if we are outside of the VMA */
 323         if (pmd_addr < vmf->vma->vm_start ||
 324                         (pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
 325                 return VM_FAULT_SIGBUS;
 326
 327         pgoff = linear_page_index(vmf->vma, pmd_addr);
 328         phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
 329         if (phys == -1) {
 330                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 331                                 pgoff);
 332                 return VM_FAULT_SIGBUS;
 333         }
 334
 335         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 336
 337         return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, pfn,
 338                         vmf->flags & FAULT_FLAG_WRITE);
 339 }
 340
 341 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 342 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 343 {
 344         unsigned long pud_addr = vmf->address & PUD_MASK;
 345         struct device *dev = &dev_dax->dev;
 346         struct dax_region *dax_region;
 347         phys_addr_t phys;
 348         pgoff_t pgoff;
 349         pfn_t pfn;
 350         unsigned int fault_size = PUD_SIZE;
 351
 352
 353         if (check_vma(dev_dax, vmf->vma, __func__))
 354                 return VM_FAULT_SIGBUS;
 355
 356         dax_region = dev_dax->region;
 357         if (dax_region->align > PUD_SIZE) {
 358                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 359                         __func__, dax_region->align, fault_size);
 360                 return VM_FAULT_SIGBUS;
 361         }
 362
 363         /* dax pud mappings require pfn_t_devmap() */
 364         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 365                 dev_dbg(dev, "%s: region lacks devmap flags\n", __func__);
 366                 return VM_FAULT_SIGBUS;
 367         }
 368
 369         if (fault_size < dax_region->align)
 370                 return VM_FAULT_SIGBUS;
 371         else if (fault_size > dax_region->align)
 372                 return VM_FAULT_FALLBACK;
 373
 374         /* if we are outside of the VMA */
 375         if (pud_addr < vmf->vma->vm_start ||
 376                         (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
 377                 return VM_FAULT_SIGBUS;
 378
 379         pgoff = linear_page_index(vmf->vma, pud_addr);
 380         phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
 381         if (phys == -1) {
 382                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 383                                 pgoff);
 384                 return VM_FAULT_SIGBUS;
 385         }
 386
 387         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 388
 389         return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, pfn,
 390                         vmf->flags & FAULT_FLAG_WRITE);
 391 }
 392 #else
 393 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 394 {
 395         return VM_FAULT_FALLBACK;
 396 }
 397 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 398
 399 static int dev_dax_huge_fault(struct vm_fault *vmf,
 400                 enum page_entry_size pe_size)
 401 {
 402         int rc, id;
 403         struct file *filp = vmf->vma->vm_file;
 404         struct dev_dax *dev_dax = filp->private_data;
 405
 406         dev_dbg(&dev_dax->dev, "%s: %s: %s (%#lx - %#lx) size = %d\n", __func__,
 407                         current->comm, (vmf->flags & FAULT_FLAG_WRITE)
 408                         ? "write" : "read",
 409                         vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 410
 411         id = dax_read_lock();
 412         switch (pe_size) {
 413         case PE_SIZE_PTE:
 414                 rc = __dev_dax_pte_fault(dev_dax, vmf);
 415                 break;
 416         case PE_SIZE_PMD:
 417                 rc = __dev_dax_pmd_fault(dev_dax, vmf);
 418                 break;
 419         case PE_SIZE_PUD:
 420                 rc = __dev_dax_pud_fault(dev_dax, vmf);
 421                 break;
 422         default:
 423                 rc = VM_FAULT_SIGBUS;
 424         }
 425         dax_read_unlock(id);
 426
 427         return rc;
 428 }
 429
 430 static int dev_dax_fault(struct vm_fault *vmf)
 431 {
 432         return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 433 }
 434
 435 static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
 436 {
 437         struct file *filp = vma->vm_file;
 438         struct dev_dax *dev_dax = filp->private_data;
 439         struct dax_region *dax_region = dev_dax->region;
 440
 441         if (!IS_ALIGNED(addr, dax_region->align))
 442                 return -EINVAL;
 443         return 0;
 444 }
 445
 446 static const struct vm_operations_struct dax_vm_ops = {
 447         .fault = dev_dax_fault,
 448         .huge_fault = dev_dax_huge_fault,
 449         .split = dev_dax_split,
 450 };
 451
 452 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 453 {
 454         struct dev_dax *dev_dax = filp->private_data;
 455         int rc, id;
 456
 457         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 458
 459         /*
 460          * We lock to check dax_dev liveness and will re-check at
 461          * fault time.
 462          */
 463         id = dax_read_lock();
 464         rc = check_vma(dev_dax, vma, __func__);
 465         dax_read_unlock(id);
 466         if (rc)
 467                 return rc;
 468
 469         vma->vm_ops = &dax_vm_ops;
 470         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 471         return 0;
 472 }
 473
 474 /* return an unmapped area aligned to the dax region specified alignment */
 475 static unsigned long dax_get_unmapped_area(struct file *filp,
 476                 unsigned long addr, unsigned long len, unsigned long pgoff,
 477                 unsigned long flags)
 478 {
 479         unsigned long off, off_end, off_align, len_align, addr_align, align;
 480         struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 481         struct dax_region *dax_region;
 482
 483         if (!dev_dax || addr)
 484                 goto out;
 485
 486         dax_region = dev_dax->region;
 487         align = dax_region->align;
 488         off = pgoff << PAGE_SHIFT;
 489         off_end = off + len;
 490         off_align = round_up(off, align);
 491
 492         if ((off_end <= off_align) || ((off_end - off_align) < align))
 493                 goto out;
 494
 495         len_align = len + align;
 496         if ((off + len_align) < off)
 497                 goto out;
 498
 499         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 500                         pgoff, flags);
 501         if (!IS_ERR_VALUE(addr_align)) {
 502                 addr_align += (off - addr_align) & (align - 1);
 503                 return addr_align;
 504         }
 505  out:
 506         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 507 }
 508
 509 static int dax_open(struct inode *inode, struct file *filp)
 510 {
 511         struct dax_device *dax_dev = inode_dax(inode);
 512         struct inode *__dax_inode = dax_inode(dax_dev);
 513         struct dev_dax *dev_dax = dax_get_private(dax_dev);
 514
 515         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 516         inode->i_mapping = __dax_inode->i_mapping;
 517         inode->i_mapping->host = __dax_inode;
 518         filp->f_mapping = inode->i_mapping;
 519         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 520         filp->private_data = dev_dax;
 521         inode->i_flags = S_DAX;
 522
 523         return 0;
 524 }
 525
 526 static int dax_release(struct inode *inode, struct file *filp)
 527 {
 528         struct dev_dax *dev_dax = filp->private_data;
 529
 530         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 531         return 0;
 532 }
 533
 534 static const struct file_operations dax_fops = {
 535         .llseek = noop_llseek,
 536         .owner = THIS_MODULE,
 537         .open = dax_open,
 538         .release = dax_release,
 539         .get_unmapped_area = dax_get_unmapped_area,
 540         .mmap = dax_mmap,
 541 };
 542
 543 static void dev_dax_release(struct device *dev)
 544 {
 545         struct dev_dax *dev_dax = to_dev_dax(dev);
 546         struct dax_region *dax_region = dev_dax->region;
 547         struct dax_device *dax_dev = dev_dax->dax_dev;
 548
 549         if (dev_dax->id >= 0)
 550                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 551         dax_region_put(dax_region);
 552         put_dax(dax_dev);
 553         kfree(dev_dax);
 554 }
 555
 556 static void kill_dev_dax(struct dev_dax *dev_dax)
 557 {
 558         struct dax_device *dax_dev = dev_dax->dax_dev;
 559         struct inode *inode = dax_inode(dax_dev);
 560
 561         kill_dax(dax_dev);
 562         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 563 }
 564
 565 static void unregister_dev_dax(void *dev)
 566 {
 567         struct dev_dax *dev_dax = to_dev_dax(dev);
 568         struct dax_device *dax_dev = dev_dax->dax_dev;
 569         struct inode *inode = dax_inode(dax_dev);
 570         struct cdev *cdev = inode->i_cdev;
 571
 572         dev_dbg(dev, "%s\n", __func__);
 573
 574         kill_dev_dax(dev_dax);
 575         cdev_device_del(cdev, dev);
 576         put_device(dev);
 577 }
 578
 579 struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
 580                 int id, struct resource *res, int count)
 581 {
 582         struct device *parent = dax_region->dev;
 583         struct dax_device *dax_dev;
 584         struct dev_dax *dev_dax;
 585         struct inode *inode;
 586         struct device *dev;
 587         struct cdev *cdev;
 588         int rc, i;
 589
 590         if (!count)
 591                 return ERR_PTR(-EINVAL);
 592
 593         dev_dax = kzalloc(sizeof(*dev_dax) + sizeof(*res) * count, GFP_KERNEL);
 594         if (!dev_dax)
 595                 return ERR_PTR(-ENOMEM);
 596
 597         for (i = 0; i < count; i++) {
 598                 if (!IS_ALIGNED(res[i].start, dax_region->align)
 599                                 || !IS_ALIGNED(resource_size(&res[i]),
 600                                         dax_region->align)) {
 601                         rc = -EINVAL;
 602                         break;
 603                 }
 604                 dev_dax->res[i].start = res[i].start;
 605                 dev_dax->res[i].end = res[i].end;
 606         }
 607
 608         if (i < count)
 609                 goto err_id;
 610
 611         if (id < 0) {
 612                 id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 613                 dev_dax->id = id;
 614                 if (id < 0) {
 615                         rc = id;
 616                         goto err_id;
 617                 }
 618         } else {
 619                 /* region provider owns @id lifetime */
 620                 dev_dax->id = -1;
 621         }
 622
 623         /*
 624          * No 'host' or dax_operations since there is no access to this
 625          * device outside of mmap of the resulting character device.
 626          */
 627         dax_dev = alloc_dax(dev_dax, NULL, NULL);
 628         if (!dax_dev) {
 629                 rc = -ENOMEM;
 630                 goto err_dax;
 631         }
 632
 633         /* from here on we're committed to teardown via dax_dev_release() */
 634         dev = &dev_dax->dev;
 635         device_initialize(dev);
 636
 637         inode = dax_inode(dax_dev);
 638         cdev = inode->i_cdev;
 639         cdev_init(cdev, &dax_fops);
 640         cdev->owner = parent->driver->owner;
 641
 642         dev_dax->num_resources = count;
 643         dev_dax->dax_dev = dax_dev;
 644         dev_dax->region = dax_region;
 645         kref_get(&dax_region->kref);
 646
 647         dev->devt = inode->i_rdev;
 648         dev->class = dax_class;
 649         dev->parent = parent;
 650         dev->groups = dax_attribute_groups;
 651         dev->release = dev_dax_release;
 652         dev_set_name(dev, "dax%d.%d", dax_region->id, id);
 653
 654         rc = cdev_device_add(cdev, dev);
 655         if (rc) {
 656                 kill_dev_dax(dev_dax);
 657                 put_device(dev);
 658                 return ERR_PTR(rc);
 659         }
 660
 661         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 662         if (rc)
 663                 return ERR_PTR(rc);
 664
 665         return dev_dax;
 666
 667  err_dax:
 668         if (dev_dax->id >= 0)
 669                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 670  err_id:
 671         kfree(dev_dax);
 672
 673         return ERR_PTR(rc);
 674 }
 675 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
 676
 677 static int __init dax_init(void)
 678 {
 679         dax_class = class_create(THIS_MODULE, "dax");
 680         return PTR_ERR_OR_ZERO(dax_class);
 681 }
 682
 683 static void __exit dax_exit(void)
 684 {
 685         class_destroy(dax_class);
 686 }
 687
 688 MODULE_AUTHOR("Intel Corporation");
 689 MODULE_LICENSE("GPL v2");
 690 subsys_initcall(dax_init);
 691 module_exit(dax_exit);