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