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 <linux/mman.h>
  23 #include "dax-private.h"
  24 #include "dax.h"
  25
  26 static struct class *dax_class;
  27
  28 /*
  29  * Rely on the fact that drvdata is set before the attributes are
  30  * registered, and that the attributes are unregistered before drvdata
  31  * is cleared to assume that drvdata is always valid.
  32  */
  33 static ssize_t id_show(struct device *dev,
  34                 struct device_attribute *attr, char *buf)
  35 {
  36         struct dax_region *dax_region = dev_get_drvdata(dev);
  37
  38         return sprintf(buf, "%d\n", dax_region->id);
  39 }
  40 static DEVICE_ATTR_RO(id);
  41
  42 static ssize_t region_size_show(struct device *dev,
  43                 struct device_attribute *attr, char *buf)
  44 {
  45         struct dax_region *dax_region = dev_get_drvdata(dev);
  46
  47         return sprintf(buf, "%llu\n", (unsigned long long)
  48                         resource_size(&dax_region->res));
  49 }
  50 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
  51                 region_size_show, NULL);
  52
  53 static ssize_t align_show(struct device *dev,
  54                 struct device_attribute *attr, char *buf)
  55 {
  56         struct dax_region *dax_region = dev_get_drvdata(dev);
  57
  58         return sprintf(buf, "%u\n", dax_region->align);
  59 }
  60 static DEVICE_ATTR_RO(align);
  61
  62 static struct attribute *dax_region_attributes[] = {
  63         &dev_attr_region_size.attr,
  64         &dev_attr_align.attr,
  65         &dev_attr_id.attr,
  66         NULL,
  67 };
  68
  69 static const struct attribute_group dax_region_attribute_group = {
  70         .name = "dax_region",
  71         .attrs = dax_region_attributes,
  72 };
  73
  74 static const struct attribute_group *dax_region_attribute_groups[] = {
  75         &dax_region_attribute_group,
  76         NULL,
  77 };
  78
  79 static void dax_region_free(struct kref *kref)
  80 {
  81         struct dax_region *dax_region;
  82
  83         dax_region = container_of(kref, struct dax_region, kref);
  84         kfree(dax_region);
  85 }
  86
  87 void dax_region_put(struct dax_region *dax_region)
  88 {
  89         kref_put(&dax_region->kref, dax_region_free);
  90 }
  91 EXPORT_SYMBOL_GPL(dax_region_put);
  92
  93 static void dax_region_unregister(void *region)
  94 {
  95         struct dax_region *dax_region = region;
  96
  97         sysfs_remove_groups(&dax_region->dev->kobj,
  98                         dax_region_attribute_groups);
  99         dax_region_put(dax_region);
 100 }
 101
 102 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 103                 struct resource *res, unsigned int align, void *addr,
 104                 unsigned long pfn_flags)
 105 {
 106         struct dax_region *dax_region;
 107
 108         /*
 109          * The DAX core assumes that it can store its private data in
 110          * parent->driver_data. This WARN is a reminder / safeguard for
 111          * developers of device-dax drivers.
 112          */
 113         if (dev_get_drvdata(parent)) {
 114                 dev_WARN(parent, "dax core failed to setup private data\n");
 115                 return NULL;
 116         }
 117
 118         if (!IS_ALIGNED(res->start, align)
 119                         || !IS_ALIGNED(resource_size(res), align))
 120                 return NULL;
 121
 122         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 123         if (!dax_region)
 124                 return NULL;
 125
 126         dev_set_drvdata(parent, dax_region);
 127         memcpy(&dax_region->res, res, sizeof(*res));
 128         dax_region->pfn_flags = pfn_flags;
 129         kref_init(&dax_region->kref);
 130         dax_region->id = region_id;
 131         ida_init(&dax_region->ida);
 132         dax_region->align = align;
 133         dax_region->dev = parent;
 134         dax_region->base = addr;
 135         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 136                 kfree(dax_region);
 137                 return NULL;
 138         }
 139
 140         kref_get(&dax_region->kref);
 141         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 142                 return NULL;
 143         return dax_region;
 144 }
 145 EXPORT_SYMBOL_GPL(alloc_dax_region);
 146
 147 static struct dev_dax *to_dev_dax(struct device *dev)
 148 {
 149         return container_of(dev, struct dev_dax, dev);
 150 }
 151
 152 static ssize_t size_show(struct device *dev,
 153                 struct device_attribute *attr, char *buf)
 154 {
 155         struct dev_dax *dev_dax = to_dev_dax(dev);
 156         unsigned long long size = 0;
 157         int i;
 158
 159         for (i = 0; i < dev_dax->num_resources; i++)
 160                 size += resource_size(&dev_dax->res[i]);
 161
 162         return sprintf(buf, "%llu\n", size);
 163 }
 164 static DEVICE_ATTR_RO(size);
 165
 166 static struct attribute *dev_dax_attributes[] = {
 167         &dev_attr_size.attr,
 168         NULL,
 169 };
 170
 171 static const struct attribute_group dev_dax_attribute_group = {
 172         .attrs = dev_dax_attributes,
 173 };
 174
 175 static const struct attribute_group *dax_attribute_groups[] = {
 176         &dev_dax_attribute_group,
 177         NULL,
 178 };
 179
 180 static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
 181                 const char *func)
 182 {
 183         struct dax_region *dax_region = dev_dax->region;
 184         struct device *dev = &dev_dax->dev;
 185         unsigned long mask;
 186
 187         if (!dax_alive(dev_dax->dax_dev))
 188                 return -ENXIO;
 189
 190         /* prevent private mappings from being established */
 191         if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
 192                 dev_info_ratelimited(dev,
 193                                 "%s: %s: fail, attempted private mapping\n",
 194                                 current->comm, func);
 195                 return -EINVAL;
 196         }
 197
 198         mask = dax_region->align - 1;
 199         if (vma->vm_start & mask || vma->vm_end & mask) {
 200                 dev_info_ratelimited(dev,
 201                                 "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
 202                                 current->comm, func, vma->vm_start, vma->vm_end,
 203                                 mask);
 204                 return -EINVAL;
 205         }
 206
 207         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
 208                         && (vma->vm_flags & VM_DONTCOPY) == 0) {
 209                 dev_info_ratelimited(dev,
 210                                 "%s: %s: fail, dax range requires MADV_DONTFORK\n",
 211                                 current->comm, func);
 212                 return -EINVAL;
 213         }
 214
 215         if (!vma_is_dax(vma)) {
 216                 dev_info_ratelimited(dev,
 217                                 "%s: %s: fail, vma is not DAX capable\n",
 218                                 current->comm, func);
 219                 return -EINVAL;
 220         }
 221
 222         return 0;
 223 }
 224
 225 /* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
 226 __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 227                 unsigned long size)
 228 {
 229         struct resource *res;
 230         /* gcc-4.6.3-nolibc for i386 complains that this is uninitialized */
 231         phys_addr_t uninitialized_var(phys);
 232         int i;
 233
 234         for (i = 0; i < dev_dax->num_resources; i++) {
 235                 res = &dev_dax->res[i];
 236                 phys = pgoff * PAGE_SIZE + res->start;
 237                 if (phys >= res->start && phys <= res->end)
 238                         break;
 239                 pgoff -= PHYS_PFN(resource_size(res));
 240         }
 241
 242         if (i < dev_dax->num_resources) {
 243                 res = &dev_dax->res[i];
 244                 if (phys + size - 1 <= res->end)
 245                         return phys;
 246         }
 247
 248         return -1;
 249 }
 250
 251 static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 252 {
 253         struct device *dev = &dev_dax->dev;
 254         struct dax_region *dax_region;
 255         int rc = VM_FAULT_SIGBUS;
 256         phys_addr_t phys;
 257         pfn_t pfn;
 258         unsigned int fault_size = PAGE_SIZE;
 259
 260         if (check_vma(dev_dax, vmf->vma, __func__))
 261                 return VM_FAULT_SIGBUS;
 262
 263         dax_region = dev_dax->region;
 264         if (dax_region->align > PAGE_SIZE) {
 265                 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 266                         dax_region->align, fault_size);
 267                 return VM_FAULT_SIGBUS;
 268         }
 269
 270         if (fault_size != dax_region->align)
 271                 return VM_FAULT_SIGBUS;
 272
 273         phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
 274         if (phys == -1) {
 275                 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", 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, "alignment (%#x) > fault size (%#x)\n",
 307                         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, "region lacks devmap flags\n");
 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, "pgoff_to_phys(%#lx) failed\n", pgoff);
 331                 return VM_FAULT_SIGBUS;
 332         }
 333
 334         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 335
 336         return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, pfn,
 337                         vmf->flags & FAULT_FLAG_WRITE);
 338 }
 339
 340 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 341 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 342 {
 343         unsigned long pud_addr = vmf->address & PUD_MASK;
 344         struct device *dev = &dev_dax->dev;
 345         struct dax_region *dax_region;
 346         phys_addr_t phys;
 347         pgoff_t pgoff;
 348         pfn_t pfn;
 349         unsigned int fault_size = PUD_SIZE;
 350
 351
 352         if (check_vma(dev_dax, vmf->vma, __func__))
 353                 return VM_FAULT_SIGBUS;
 354
 355         dax_region = dev_dax->region;
 356         if (dax_region->align > PUD_SIZE) {
 357                 dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 358                         dax_region->align, fault_size);
 359                 return VM_FAULT_SIGBUS;
 360         }
 361
 362         /* dax pud mappings require pfn_t_devmap() */
 363         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 364                 dev_dbg(dev, "region lacks devmap flags\n");
 365                 return VM_FAULT_SIGBUS;
 366         }
 367
 368         if (fault_size < dax_region->align)
 369                 return VM_FAULT_SIGBUS;
 370         else if (fault_size > dax_region->align)
 371                 return VM_FAULT_FALLBACK;
 372
 373         /* if we are outside of the VMA */
 374         if (pud_addr < vmf->vma->vm_start ||
 375                         (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
 376                 return VM_FAULT_SIGBUS;
 377
 378         pgoff = linear_page_index(vmf->vma, pud_addr);
 379         phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
 380         if (phys == -1) {
 381                 dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 382                 return VM_FAULT_SIGBUS;
 383         }
 384
 385         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 386
 387         return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, pfn,
 388                         vmf->flags & FAULT_FLAG_WRITE);
 389 }
 390 #else
 391 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 392 {
 393         return VM_FAULT_FALLBACK;
 394 }
 395 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 396
 397 static int dev_dax_huge_fault(struct vm_fault *vmf,
 398                 enum page_entry_size pe_size)
 399 {
 400         int rc, id;
 401         struct file *filp = vmf->vma->vm_file;
 402         struct dev_dax *dev_dax = filp->private_data;
 403
 404         dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
 405                         (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
 406                         vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 407
 408         id = dax_read_lock();
 409         switch (pe_size) {
 410         case PE_SIZE_PTE:
 411                 rc = __dev_dax_pte_fault(dev_dax, vmf);
 412                 break;
 413         case PE_SIZE_PMD:
 414                 rc = __dev_dax_pmd_fault(dev_dax, vmf);
 415                 break;
 416         case PE_SIZE_PUD:
 417                 rc = __dev_dax_pud_fault(dev_dax, vmf);
 418                 break;
 419         default:
 420                 rc = VM_FAULT_SIGBUS;
 421         }
 422         dax_read_unlock(id);
 423
 424         return rc;
 425 }
 426
 427 static int dev_dax_fault(struct vm_fault *vmf)
 428 {
 429         return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 430 }
 431
 432 static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
 433 {
 434         struct file *filp = vma->vm_file;
 435         struct dev_dax *dev_dax = filp->private_data;
 436         struct dax_region *dax_region = dev_dax->region;
 437
 438         if (!IS_ALIGNED(addr, dax_region->align))
 439                 return -EINVAL;
 440         return 0;
 441 }
 442
 443 static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
 444 {
 445         struct file *filp = vma->vm_file;
 446         struct dev_dax *dev_dax = filp->private_data;
 447         struct dax_region *dax_region = dev_dax->region;
 448
 449         return dax_region->align;
 450 }
 451
 452 static const struct vm_operations_struct dax_vm_ops = {
 453         .fault = dev_dax_fault,
 454         .huge_fault = dev_dax_huge_fault,
 455         .split = dev_dax_split,
 456         .pagesize = dev_dax_pagesize,
 457 };
 458
 459 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 460 {
 461         struct dev_dax *dev_dax = filp->private_data;
 462         int rc, id;
 463
 464         dev_dbg(&dev_dax->dev, "trace\n");
 465
 466         /*
 467          * We lock to check dax_dev liveness and will re-check at
 468          * fault time.
 469          */
 470         id = dax_read_lock();
 471         rc = check_vma(dev_dax, vma, __func__);
 472         dax_read_unlock(id);
 473         if (rc)
 474                 return rc;
 475
 476         vma->vm_ops = &dax_vm_ops;
 477         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 478         return 0;
 479 }
 480
 481 /* return an unmapped area aligned to the dax region specified alignment */
 482 static unsigned long dax_get_unmapped_area(struct file *filp,
 483                 unsigned long addr, unsigned long len, unsigned long pgoff,
 484                 unsigned long flags)
 485 {
 486         unsigned long off, off_end, off_align, len_align, addr_align, align;
 487         struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 488         struct dax_region *dax_region;
 489
 490         if (!dev_dax || addr)
 491                 goto out;
 492
 493         dax_region = dev_dax->region;
 494         align = dax_region->align;
 495         off = pgoff << PAGE_SHIFT;
 496         off_end = off + len;
 497         off_align = round_up(off, align);
 498
 499         if ((off_end <= off_align) || ((off_end - off_align) < align))
 500                 goto out;
 501
 502         len_align = len + align;
 503         if ((off + len_align) < off)
 504                 goto out;
 505
 506         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 507                         pgoff, flags);
 508         if (!IS_ERR_VALUE(addr_align)) {
 509                 addr_align += (off - addr_align) & (align - 1);
 510                 return addr_align;
 511         }
 512  out:
 513         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 514 }
 515
 516 static int dax_open(struct inode *inode, struct file *filp)
 517 {
 518         struct dax_device *dax_dev = inode_dax(inode);
 519         struct inode *__dax_inode = dax_inode(dax_dev);
 520         struct dev_dax *dev_dax = dax_get_private(dax_dev);
 521
 522         dev_dbg(&dev_dax->dev, "trace\n");
 523         inode->i_mapping = __dax_inode->i_mapping;
 524         inode->i_mapping->host = __dax_inode;
 525         filp->f_mapping = inode->i_mapping;
 526         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 527         filp->private_data = dev_dax;
 528         inode->i_flags = S_DAX;
 529
 530         return 0;
 531 }
 532
 533 static int dax_release(struct inode *inode, struct file *filp)
 534 {
 535         struct dev_dax *dev_dax = filp->private_data;
 536
 537         dev_dbg(&dev_dax->dev, "trace\n");
 538         return 0;
 539 }
 540
 541 static const struct file_operations dax_fops = {
 542         .llseek = noop_llseek,
 543         .owner = THIS_MODULE,
 544         .open = dax_open,
 545         .release = dax_release,
 546         .get_unmapped_area = dax_get_unmapped_area,
 547         .mmap = dax_mmap,
 548         .mmap_supported_flags = MAP_SYNC,
 549 };
 550
 551 static void dev_dax_release(struct device *dev)
 552 {
 553         struct dev_dax *dev_dax = to_dev_dax(dev);
 554         struct dax_region *dax_region = dev_dax->region;
 555         struct dax_device *dax_dev = dev_dax->dax_dev;
 556
 557         if (dev_dax->id >= 0)
 558                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 559         dax_region_put(dax_region);
 560         put_dax(dax_dev);
 561         kfree(dev_dax);
 562 }
 563
 564 static void kill_dev_dax(struct dev_dax *dev_dax)
 565 {
 566         struct dax_device *dax_dev = dev_dax->dax_dev;
 567         struct inode *inode = dax_inode(dax_dev);
 568
 569         kill_dax(dax_dev);
 570         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 571 }
 572
 573 static void unregister_dev_dax(void *dev)
 574 {
 575         struct dev_dax *dev_dax = to_dev_dax(dev);
 576         struct dax_device *dax_dev = dev_dax->dax_dev;
 577         struct inode *inode = dax_inode(dax_dev);
 578         struct cdev *cdev = inode->i_cdev;
 579
 580         dev_dbg(dev, "trace\n");
 581
 582         kill_dev_dax(dev_dax);
 583         cdev_device_del(cdev, dev);
 584         put_device(dev);
 585 }
 586
 587 struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
 588                 int id, struct resource *res, int count)
 589 {
 590         struct device *parent = dax_region->dev;
 591         struct dax_device *dax_dev;
 592         struct dev_dax *dev_dax;
 593         struct inode *inode;
 594         struct device *dev;
 595         struct cdev *cdev;
 596         int rc, i;
 597
 598         if (!count)
 599                 return ERR_PTR(-EINVAL);
 600
 601         dev_dax = kzalloc(struct_size(dev_dax, res, count), GFP_KERNEL);
 602         if (!dev_dax)
 603                 return ERR_PTR(-ENOMEM);
 604
 605         for (i = 0; i < count; i++) {
 606                 if (!IS_ALIGNED(res[i].start, dax_region->align)
 607                                 || !IS_ALIGNED(resource_size(&res[i]),
 608                                         dax_region->align)) {
 609                         rc = -EINVAL;
 610                         break;
 611                 }
 612                 dev_dax->res[i].start = res[i].start;
 613                 dev_dax->res[i].end = res[i].end;
 614         }
 615
 616         if (i < count)
 617                 goto err_id;
 618
 619         if (id < 0) {
 620                 id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 621                 dev_dax->id = id;
 622                 if (id < 0) {
 623                         rc = id;
 624                         goto err_id;
 625                 }
 626         } else {
 627                 /* region provider owns @id lifetime */
 628                 dev_dax->id = -1;
 629         }
 630
 631         /*
 632          * No 'host' or dax_operations since there is no access to this
 633          * device outside of mmap of the resulting character device.
 634          */
 635         dax_dev = alloc_dax(dev_dax, NULL, NULL);
 636         if (!dax_dev) {
 637                 rc = -ENOMEM;
 638                 goto err_dax;
 639         }
 640
 641         /* from here on we're committed to teardown via dax_dev_release() */
 642         dev = &dev_dax->dev;
 643         device_initialize(dev);
 644
 645         inode = dax_inode(dax_dev);
 646         cdev = inode->i_cdev;
 647         cdev_init(cdev, &dax_fops);
 648         cdev->owner = parent->driver->owner;
 649
 650         dev_dax->num_resources = count;
 651         dev_dax->dax_dev = dax_dev;
 652         dev_dax->region = dax_region;
 653         kref_get(&dax_region->kref);
 654
 655         dev->devt = inode->i_rdev;
 656         dev->class = dax_class;
 657         dev->parent = parent;
 658         dev->groups = dax_attribute_groups;
 659         dev->release = dev_dax_release;
 660         dev_set_name(dev, "dax%d.%d", dax_region->id, id);
 661
 662         rc = cdev_device_add(cdev, dev);
 663         if (rc) {
 664                 kill_dev_dax(dev_dax);
 665                 put_device(dev);
 666                 return ERR_PTR(rc);
 667         }
 668
 669         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 670         if (rc)
 671                 return ERR_PTR(rc);
 672
 673         return dev_dax;
 674
 675  err_dax:
 676         if (dev_dax->id >= 0)
 677                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 678  err_id:
 679         kfree(dev_dax);
 680
 681         return ERR_PTR(rc);
 682 }
 683 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
 684
 685 static int __init dax_init(void)
 686 {
 687         dax_class = class_create(THIS_MODULE, "dax");
 688         return PTR_ERR_OR_ZERO(dax_class);
 689 }
 690
 691 static void __exit dax_exit(void)
 692 {
 693         class_destroy(dax_class);
 694 }
 695
 696 MODULE_AUTHOR("Intel Corporation");
 697 MODULE_LICENSE("GPL v2");
 698 subsys_initcall(dax_init);
 699 module_exit(dax_exit);