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         phys_addr_t phys;
 226         int i;
 227
 228         for (i = 0; i < dev_dax->num_resources; i++) {
 229                 res = &dev_dax->res[i];
 230                 phys = pgoff * PAGE_SIZE + res->start;
 231                 if (phys >= res->start && phys <= res->end)
 232                         break;
 233                 pgoff -= PHYS_PFN(resource_size(res));
 234         }
 235
 236         if (i < dev_dax->num_resources) {
 237                 res = &dev_dax->res[i];
 238                 if (phys + size - 1 <= res->end)
 239                         return phys;
 240         }
 241
 242         return -1;
 243 }
 244
 245 static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 246 {
 247         struct device *dev = &dev_dax->dev;
 248         struct dax_region *dax_region;
 249         int rc = VM_FAULT_SIGBUS;
 250         phys_addr_t phys;
 251         pfn_t pfn;
 252         unsigned int fault_size = PAGE_SIZE;
 253
 254         if (check_vma(dev_dax, vmf->vma, __func__))
 255                 return VM_FAULT_SIGBUS;
 256
 257         dax_region = dev_dax->region;
 258         if (dax_region->align > PAGE_SIZE) {
 259                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 260                         __func__, dax_region->align, fault_size);
 261                 return VM_FAULT_SIGBUS;
 262         }
 263
 264         if (fault_size != dax_region->align)
 265                 return VM_FAULT_SIGBUS;
 266
 267         phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
 268         if (phys == -1) {
 269                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 270                                 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, "%s: alignment (%#x) > fault size (%#x)\n",
 302                         __func__, 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, "%s: region lacks devmap flags\n", __func__);
 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, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 326                                 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, "%s: alignment (%#x) > fault size (%#x)\n",
 354                         __func__, 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, "%s: region lacks devmap flags\n", __func__);
 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, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 378                                 pgoff);
 379                 return VM_FAULT_SIGBUS;
 380         }
 381
 382         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 383
 384         return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, pfn,
 385                         vmf->flags & FAULT_FLAG_WRITE);
 386 }
 387 #else
 388 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 389 {
 390         return VM_FAULT_FALLBACK;
 391 }
 392 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 393
 394 static int dev_dax_huge_fault(struct vm_fault *vmf,
 395                 enum page_entry_size pe_size)
 396 {
 397         int rc, id;
 398         struct file *filp = vmf->vma->vm_file;
 399         struct dev_dax *dev_dax = filp->private_data;
 400
 401         dev_dbg(&dev_dax->dev, "%s: %s: %s (%#lx - %#lx) size = %d\n", __func__,
 402                         current->comm, (vmf->flags & FAULT_FLAG_WRITE)
 403                         ? "write" : "read",
 404                         vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 405
 406         id = dax_read_lock();
 407         switch (pe_size) {
 408         case PE_SIZE_PTE:
 409                 rc = __dev_dax_pte_fault(dev_dax, vmf);
 410                 break;
 411         case PE_SIZE_PMD:
 412                 rc = __dev_dax_pmd_fault(dev_dax, vmf);
 413                 break;
 414         case PE_SIZE_PUD:
 415                 rc = __dev_dax_pud_fault(dev_dax, vmf);
 416                 break;
 417         default:
 418                 rc = VM_FAULT_SIGBUS;
 419         }
 420         dax_read_unlock(id);
 421
 422         return rc;
 423 }
 424
 425 static int dev_dax_fault(struct vm_fault *vmf)
 426 {
 427         return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 428 }
 429
 430 static const struct vm_operations_struct dax_vm_ops = {
 431         .fault = dev_dax_fault,
 432         .huge_fault = dev_dax_huge_fault,
 433 };
 434
 435 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 436 {
 437         struct dev_dax *dev_dax = filp->private_data;
 438         int rc, id;
 439
 440         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 441
 442         /*
 443          * We lock to check dax_dev liveness and will re-check at
 444          * fault time.
 445          */
 446         id = dax_read_lock();
 447         rc = check_vma(dev_dax, vma, __func__);
 448         dax_read_unlock(id);
 449         if (rc)
 450                 return rc;
 451
 452         vma->vm_ops = &dax_vm_ops;
 453         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 454         return 0;
 455 }
 456
 457 /* return an unmapped area aligned to the dax region specified alignment */
 458 static unsigned long dax_get_unmapped_area(struct file *filp,
 459                 unsigned long addr, unsigned long len, unsigned long pgoff,
 460                 unsigned long flags)
 461 {
 462         unsigned long off, off_end, off_align, len_align, addr_align, align;
 463         struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 464         struct dax_region *dax_region;
 465
 466         if (!dev_dax || addr)
 467                 goto out;
 468
 469         dax_region = dev_dax->region;
 470         align = dax_region->align;
 471         off = pgoff << PAGE_SHIFT;
 472         off_end = off + len;
 473         off_align = round_up(off, align);
 474
 475         if ((off_end <= off_align) || ((off_end - off_align) < align))
 476                 goto out;
 477
 478         len_align = len + align;
 479         if ((off + len_align) < off)
 480                 goto out;
 481
 482         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 483                         pgoff, flags);
 484         if (!IS_ERR_VALUE(addr_align)) {
 485                 addr_align += (off - addr_align) & (align - 1);
 486                 return addr_align;
 487         }
 488  out:
 489         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 490 }
 491
 492 static int dax_open(struct inode *inode, struct file *filp)
 493 {
 494         struct dax_device *dax_dev = inode_dax(inode);
 495         struct inode *__dax_inode = dax_inode(dax_dev);
 496         struct dev_dax *dev_dax = dax_get_private(dax_dev);
 497
 498         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 499         inode->i_mapping = __dax_inode->i_mapping;
 500         inode->i_mapping->host = __dax_inode;
 501         filp->f_mapping = inode->i_mapping;
 502         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 503         filp->private_data = dev_dax;
 504         inode->i_flags = S_DAX;
 505
 506         return 0;
 507 }
 508
 509 static int dax_release(struct inode *inode, struct file *filp)
 510 {
 511         struct dev_dax *dev_dax = filp->private_data;
 512
 513         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 514         return 0;
 515 }
 516
 517 static const struct file_operations dax_fops = {
 518         .llseek = noop_llseek,
 519         .owner = THIS_MODULE,
 520         .open = dax_open,
 521         .release = dax_release,
 522         .get_unmapped_area = dax_get_unmapped_area,
 523         .mmap = dax_mmap,
 524 };
 525
 526 static void dev_dax_release(struct device *dev)
 527 {
 528         struct dev_dax *dev_dax = to_dev_dax(dev);
 529         struct dax_region *dax_region = dev_dax->region;
 530         struct dax_device *dax_dev = dev_dax->dax_dev;
 531
 532         if (dev_dax->id >= 0)
 533                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 534         dax_region_put(dax_region);
 535         put_dax(dax_dev);
 536         kfree(dev_dax);
 537 }
 538
 539 static void kill_dev_dax(struct dev_dax *dev_dax)
 540 {
 541         struct dax_device *dax_dev = dev_dax->dax_dev;
 542         struct inode *inode = dax_inode(dax_dev);
 543
 544         kill_dax(dax_dev);
 545         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 546 }
 547
 548 static void unregister_dev_dax(void *dev)
 549 {
 550         struct dev_dax *dev_dax = to_dev_dax(dev);
 551         struct dax_device *dax_dev = dev_dax->dax_dev;
 552         struct inode *inode = dax_inode(dax_dev);
 553         struct cdev *cdev = inode->i_cdev;
 554
 555         dev_dbg(dev, "%s\n", __func__);
 556
 557         kill_dev_dax(dev_dax);
 558         cdev_device_del(cdev, dev);
 559         put_device(dev);
 560 }
 561
 562 struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
 563                 int id, struct resource *res, int count)
 564 {
 565         struct device *parent = dax_region->dev;
 566         struct dax_device *dax_dev;
 567         struct dev_dax *dev_dax;
 568         struct inode *inode;
 569         struct device *dev;
 570         struct cdev *cdev;
 571         int rc, i;
 572
 573         if (!count)
 574                 return ERR_PTR(-EINVAL);
 575
 576         dev_dax = kzalloc(sizeof(*dev_dax) + sizeof(*res) * count, GFP_KERNEL);
 577         if (!dev_dax)
 578                 return ERR_PTR(-ENOMEM);
 579
 580         for (i = 0; i < count; i++) {
 581                 if (!IS_ALIGNED(res[i].start, dax_region->align)
 582                                 || !IS_ALIGNED(resource_size(&res[i]),
 583                                         dax_region->align)) {
 584                         rc = -EINVAL;
 585                         break;
 586                 }
 587                 dev_dax->res[i].start = res[i].start;
 588                 dev_dax->res[i].end = res[i].end;
 589         }
 590
 591         if (i < count)
 592                 goto err_id;
 593
 594         if (id < 0) {
 595                 id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 596                 dev_dax->id = id;
 597                 if (id < 0) {
 598                         rc = id;
 599                         goto err_id;
 600                 }
 601         } else {
 602                 /* region provider owns @id lifetime */
 603                 dev_dax->id = -1;
 604         }
 605
 606         /*
 607          * No 'host' or dax_operations since there is no access to this
 608          * device outside of mmap of the resulting character device.
 609          */
 610         dax_dev = alloc_dax(dev_dax, NULL, NULL);
 611         if (!dax_dev) {
 612                 rc = -ENOMEM;
 613                 goto err_dax;
 614         }
 615
 616         /* from here on we're committed to teardown via dax_dev_release() */
 617         dev = &dev_dax->dev;
 618         device_initialize(dev);
 619
 620         inode = dax_inode(dax_dev);
 621         cdev = inode->i_cdev;
 622         cdev_init(cdev, &dax_fops);
 623         cdev->owner = parent->driver->owner;
 624
 625         dev_dax->num_resources = count;
 626         dev_dax->dax_dev = dax_dev;
 627         dev_dax->region = dax_region;
 628         kref_get(&dax_region->kref);
 629
 630         dev->devt = inode->i_rdev;
 631         dev->class = dax_class;
 632         dev->parent = parent;
 633         dev->groups = dax_attribute_groups;
 634         dev->release = dev_dax_release;
 635         dev_set_name(dev, "dax%d.%d", dax_region->id, id);
 636
 637         rc = cdev_device_add(cdev, dev);
 638         if (rc) {
 639                 kill_dev_dax(dev_dax);
 640                 put_device(dev);
 641                 return ERR_PTR(rc);
 642         }
 643
 644         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 645         if (rc)
 646                 return ERR_PTR(rc);
 647
 648         return dev_dax;
 649
 650  err_dax:
 651         if (dev_dax->id >= 0)
 652                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 653  err_id:
 654         kfree(dev_dax);
 655
 656         return ERR_PTR(rc);
 657 }
 658 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
 659
 660 static int __init dax_init(void)
 661 {
 662         dax_class = class_create(THIS_MODULE, "dax");
 663         return PTR_ERR_OR_ZERO(dax_class);
 664 }
 665
 666 static void __exit dax_exit(void)
 667 {
 668         class_destroy(dax_class);
 669 }
 670
 671 MODULE_AUTHOR("Intel Corporation");
 672 MODULE_LICENSE("GPL v2");
 673 subsys_initcall(dax_init);
 674 module_exit(dax_exit);