drivers/gpu/drm/drm_gem.c

   1 /*
   2  * Copyright © 2008 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  *    Eric Anholt <eric@anholt.net>
  25  *
  26  */
  27
  28 #include <linux/types.h>
  29 #include <linux/slab.h>
  30 #include <linux/mm.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/fs.h>
  33 #include <linux/file.h>
  34 #include <linux/module.h>
  35 #include <linux/mman.h>
  36 #include <linux/pagemap.h>
  37 #include <linux/shmem_fs.h>
  38 #include "drmP.h"
  39
  40 /** @file drm_gem.c
  41  *
  42  * This file provides some of the base ioctls and library routines for
  43  * the graphics memory manager implemented by each device driver.
  44  *
  45  * Because various devices have different requirements in terms of
  46  * synchronization and migration strategies, implementing that is left up to
  47  * the driver, and all that the general API provides should be generic --
  48  * allocating objects, reading/writing data with the cpu, freeing objects.
  49  * Even there, platform-dependent optimizations for reading/writing data with
  50  * the CPU mean we'll likely hook those out to driver-specific calls.  However,
  51  * the DRI2 implementation wants to have at least allocate/mmap be generic.
  52  *
  53  * The goal was to have swap-backed object allocation managed through
  54  * struct file.  However, file descriptors as handles to a struct file have
  55  * two major failings:
  56  * - Process limits prevent more than 1024 or so being used at a time by
  57  *   default.
  58  * - Inability to allocate high fds will aggravate the X Server's select()
  59  *   handling, and likely that of many GL client applications as well.
  60  *
  61  * This led to a plan of using our own integer IDs (called handles, following
  62  * DRM terminology) to mimic fds, and implement the fd syscalls we need as
  63  * ioctls.  The objects themselves will still include the struct file so
  64  * that we can transition to fds if the required kernel infrastructure shows
  65  * up at a later date, and as our interface with shmfs for memory allocation.
  66  */
  67
  68 /*
  69  * We make up offsets for buffer objects so we can recognize them at
  70  * mmap time.
  71  */
  72
  73 /* pgoff in mmap is an unsigned long, so we need to make sure that
  74  * the faked up offset will fit
  75  */
  76
  77 #if BITS_PER_LONG == 64
  78 #define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFFUL >> PAGE_SHIFT) + 1)
  79 #define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFFUL >> PAGE_SHIFT) * 16)
  80 #else
  81 #define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFUL >> PAGE_SHIFT) + 1)
  82 #define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFUL >> PAGE_SHIFT) * 16)
  83 #endif
  84
  85 /**
  86  * Initialize the GEM device fields
  87  */
  88
  89 int
  90 drm_gem_init(struct drm_device *dev)
  91 {
  92         struct drm_gem_mm *mm;
  93
  94         spin_lock_init(&dev->object_name_lock);
  95         idr_init(&dev->object_name_idr);
  96
  97         mm = kzalloc(sizeof(struct drm_gem_mm), GFP_KERNEL);
  98         if (!mm) {
  99                 DRM_ERROR("out of memory\n");
 100                 return -ENOMEM;
 101         }
 102
 103         dev->mm_private = mm;
 104
 105         if (drm_ht_create(&mm->offset_hash, 12)) {
 106                 kfree(mm);
 107                 return -ENOMEM;
 108         }
 109
 110         if (drm_mm_init(&mm->offset_manager, DRM_FILE_PAGE_OFFSET_START,
 111                         DRM_FILE_PAGE_OFFSET_SIZE)) {
 112                 drm_ht_remove(&mm->offset_hash);
 113                 kfree(mm);
 114                 return -ENOMEM;
 115         }
 116
 117         return 0;
 118 }
 119
 120 void
 121 drm_gem_destroy(struct drm_device *dev)
 122 {
 123         struct drm_gem_mm *mm = dev->mm_private;
 124
 125         drm_mm_takedown(&mm->offset_manager);
 126         drm_ht_remove(&mm->offset_hash);
 127         kfree(mm);
 128         dev->mm_private = NULL;
 129 }
 130
 131 /**
 132  * Initialize an already allocated GEM object of the specified size with
 133  * shmfs backing store.
 134  */
 135 int drm_gem_object_init(struct drm_device *dev,
 136                         struct drm_gem_object *obj, size_t size)
 137 {
 138         BUG_ON((size & (PAGE_SIZE - 1)) != 0);
 139
 140         obj->dev = dev;
 141         obj->filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
 142         if (IS_ERR(obj->filp))
 143                 return -ENOMEM;
 144
 145         kref_init(&obj->refcount);
 146         atomic_set(&obj->handle_count, 0);
 147         obj->size = size;
 148
 149         return 0;
 150 }
 151 EXPORT_SYMBOL(drm_gem_object_init);
 152
 153 /**
 154  * Initialize an already allocated GEM object of the specified size with
 155  * no GEM provided backing store. Instead the caller is responsible for
 156  * backing the object and handling it.
 157  */
 158 int drm_gem_private_object_init(struct drm_device *dev,
 159                         struct drm_gem_object *obj, size_t size)
 160 {
 161         BUG_ON((size & (PAGE_SIZE - 1)) != 0);
 162
 163         obj->dev = dev;
 164         obj->filp = NULL;
 165
 166         kref_init(&obj->refcount);
 167         atomic_set(&obj->handle_count, 0);
 168         obj->size = size;
 169
 170         return 0;
 171 }
 172 EXPORT_SYMBOL(drm_gem_private_object_init);
 173
 174 /**
 175  * Allocate a GEM object of the specified size with shmfs backing store
 176  */
 177 struct drm_gem_object *
 178 drm_gem_object_alloc(struct drm_device *dev, size_t size)
 179 {
 180         struct drm_gem_object *obj;
 181
 182         obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 183         if (!obj)
 184                 goto free;
 185
 186         if (drm_gem_object_init(dev, obj, size) != 0)
 187                 goto free;
 188
 189         if (dev->driver->gem_init_object != NULL &&
 190             dev->driver->gem_init_object(obj) != 0) {
 191                 goto fput;
 192         }
 193         return obj;
 194 fput:
 195         /* Object_init mangles the global counters - readjust them. */
 196         fput(obj->filp);
 197 free:
 198         kfree(obj);
 199         return NULL;
 200 }
 201 EXPORT_SYMBOL(drm_gem_object_alloc);
 202
 203 /**
 204  * Removes the mapping from handle to filp for this object.
 205  */
 206 int
 207 drm_gem_handle_delete(struct drm_file *filp, u32 handle)
 208 {
 209         struct drm_device *dev;
 210         struct drm_gem_object *obj;
 211
 212         /* This is gross. The idr system doesn't let us try a delete and
 213          * return an error code.  It just spews if you fail at deleting.
 214          * So, we have to grab a lock around finding the object and then
 215          * doing the delete on it and dropping the refcount, or the user
 216          * could race us to double-decrement the refcount and cause a
 217          * use-after-free later.  Given the frequency of our handle lookups,
 218          * we may want to use ida for number allocation and a hash table
 219          * for the pointers, anyway.
 220          */
 221         spin_lock(&filp->table_lock);
 222
 223         /* Check if we currently have a reference on the object */
 224         obj = idr_find(&filp->object_idr, handle);
 225         if (obj == NULL) {
 226                 spin_unlock(&filp->table_lock);
 227                 return -EINVAL;
 228         }
 229         dev = obj->dev;
 230
 231         /* Release reference and decrement refcount. */
 232         idr_remove(&filp->object_idr, handle);
 233         spin_unlock(&filp->table_lock);
 234
 235         if (dev->driver->gem_close_object)
 236                 dev->driver->gem_close_object(obj, filp);
 237         drm_gem_object_handle_unreference_unlocked(obj);
 238
 239         return 0;
 240 }
 241 EXPORT_SYMBOL(drm_gem_handle_delete);
 242
 243 /**
 244  * Create a handle for this object. This adds a handle reference
 245  * to the object, which includes a regular reference count. Callers
 246  * will likely want to dereference the object afterwards.
 247  */
 248 int
 249 drm_gem_handle_create(struct drm_file *file_priv,
 250                        struct drm_gem_object *obj,
 251                        u32 *handlep)
 252 {
 253         struct drm_device *dev = obj->dev;
 254         int ret;
 255
 256         /*
 257          * Get the user-visible handle using idr.
 258          */
 259 again:
 260         /* ensure there is space available to allocate a handle */
 261         if (idr_pre_get(&file_priv->object_idr, GFP_KERNEL) == 0)
 262                 return -ENOMEM;
 263
 264         /* do the allocation under our spinlock */
 265         spin_lock(&file_priv->table_lock);
 266         ret = idr_get_new_above(&file_priv->object_idr, obj, 1, (int *)handlep);
 267         spin_unlock(&file_priv->table_lock);
 268         if (ret == -EAGAIN)
 269                 goto again;
 270
 271         if (ret != 0)
 272                 return ret;
 273
 274         drm_gem_object_handle_reference(obj);
 275
 276         if (dev->driver->gem_open_object) {
 277                 ret = dev->driver->gem_open_object(obj, file_priv);
 278                 if (ret) {
 279                         drm_gem_handle_delete(file_priv, *handlep);
 280                         return ret;
 281                 }
 282         }
 283
 284         return 0;
 285 }
 286 EXPORT_SYMBOL(drm_gem_handle_create);
 287
 288
 289 /**
 290  * drm_gem_free_mmap_offset - release a fake mmap offset for an object
 291  * @obj: obj in question
 292  *
 293  * This routine frees fake offsets allocated by drm_gem_create_mmap_offset().
 294  */
 295 void
 296 drm_gem_free_mmap_offset(struct drm_gem_object *obj)
 297 {
 298         struct drm_device *dev = obj->dev;
 299         struct drm_gem_mm *mm = dev->mm_private;
 300         struct drm_map_list *list = &obj->map_list;
 301
 302         drm_ht_remove_item(&mm->offset_hash, &list->hash);
 303         drm_mm_put_block(list->file_offset_node);
 304         kfree(list->map);
 305         list->map = NULL;
 306 }
 307 EXPORT_SYMBOL(drm_gem_free_mmap_offset);
 308
 309 /**
 310  * drm_gem_create_mmap_offset - create a fake mmap offset for an object
 311  * @obj: obj in question
 312  *
 313  * GEM memory mapping works by handing back to userspace a fake mmap offset
 314  * it can use in a subsequent mmap(2) call.  The DRM core code then looks
 315  * up the object based on the offset and sets up the various memory mapping
 316  * structures.
 317  *
 318  * This routine allocates and attaches a fake offset for @obj.
 319  */
 320 int
 321 drm_gem_create_mmap_offset(struct drm_gem_object *obj)
 322 {
 323         struct drm_device *dev = obj->dev;
 324         struct drm_gem_mm *mm = dev->mm_private;
 325         struct drm_map_list *list;
 326         struct drm_local_map *map;
 327         int ret = 0;
 328
 329         /* Set the object up for mmap'ing */
 330         list = &obj->map_list;
 331         list->map = kzalloc(sizeof(struct drm_map_list), GFP_KERNEL);
 332         if (!list->map)
 333                 return -ENOMEM;
 334
 335         map = list->map;
 336         map->type = _DRM_GEM;
 337         map->size = obj->size;
 338         map->handle = obj;
 339
 340         /* Get a DRM GEM mmap offset allocated... */
 341         list->file_offset_node = drm_mm_search_free(&mm->offset_manager,
 342                         obj->size / PAGE_SIZE, 0, 0);
 343
 344         if (!list->file_offset_node) {
 345                 DRM_ERROR("failed to allocate offset for bo %d\n", obj->name);
 346                 ret = -ENOSPC;
 347                 goto out_free_list;
 348         }
 349
 350         list->file_offset_node = drm_mm_get_block(list->file_offset_node,
 351                         obj->size / PAGE_SIZE, 0);
 352         if (!list->file_offset_node) {
 353                 ret = -ENOMEM;
 354                 goto out_free_list;
 355         }
 356
 357         list->hash.key = list->file_offset_node->start;
 358         ret = drm_ht_insert_item(&mm->offset_hash, &list->hash);
 359         if (ret) {
 360                 DRM_ERROR("failed to add to map hash\n");
 361                 goto out_free_mm;
 362         }
 363
 364         return 0;
 365
 366 out_free_mm:
 367         drm_mm_put_block(list->file_offset_node);
 368 out_free_list:
 369         kfree(list->map);
 370         list->map = NULL;
 371
 372         return ret;
 373 }
 374 EXPORT_SYMBOL(drm_gem_create_mmap_offset);
 375
 376 /** Returns a reference to the object named by the handle. */
 377 struct drm_gem_object *
 378 drm_gem_object_lookup(struct drm_device *dev, struct drm_file *filp,
 379                       u32 handle)
 380 {
 381         struct drm_gem_object *obj;
 382
 383         spin_lock(&filp->table_lock);
 384
 385         /* Check if we currently have a reference on the object */
 386         obj = idr_find(&filp->object_idr, handle);
 387         if (obj == NULL) {
 388                 spin_unlock(&filp->table_lock);
 389                 return NULL;
 390         }
 391
 392         drm_gem_object_reference(obj);
 393
 394         spin_unlock(&filp->table_lock);
 395
 396         return obj;
 397 }
 398 EXPORT_SYMBOL(drm_gem_object_lookup);
 399
 400 /**
 401  * Releases the handle to an mm object.
 402  */
 403 int
 404 drm_gem_close_ioctl(struct drm_device *dev, void *data,
 405                     struct drm_file *file_priv)
 406 {
 407         struct drm_gem_close *args = data;
 408         int ret;
 409
 410         if (!(dev->driver->driver_features & DRIVER_GEM))
 411                 return -ENODEV;
 412
 413         ret = drm_gem_handle_delete(file_priv, args->handle);
 414
 415         return ret;
 416 }
 417
 418 /**
 419  * Create a global name for an object, returning the name.
 420  *
 421  * Note that the name does not hold a reference; when the object
 422  * is freed, the name goes away.
 423  */
 424 int
 425 drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 426                     struct drm_file *file_priv)
 427 {
 428         struct drm_gem_flink *args = data;
 429         struct drm_gem_object *obj;
 430         int ret;
 431
 432         if (!(dev->driver->driver_features & DRIVER_GEM))
 433                 return -ENODEV;
 434
 435         obj = drm_gem_object_lookup(dev, file_priv, args->handle);
 436         if (obj == NULL)
 437                 return -ENOENT;
 438
 439 again:
 440         if (idr_pre_get(&dev->object_name_idr, GFP_KERNEL) == 0) {
 441                 ret = -ENOMEM;
 442                 goto err;
 443         }
 444
 445         spin_lock(&dev->object_name_lock);
 446         if (!obj->name) {
 447                 ret = idr_get_new_above(&dev->object_name_idr, obj, 1,
 448                                         &obj->name);
 449                 args->name = (uint64_t) obj->name;
 450                 spin_unlock(&dev->object_name_lock);
 451
 452                 if (ret == -EAGAIN)
 453                         goto again;
 454
 455                 if (ret != 0)
 456                         goto err;
 457
 458                 /* Allocate a reference for the name table.  */
 459                 drm_gem_object_reference(obj);
 460         } else {
 461                 args->name = (uint64_t) obj->name;
 462                 spin_unlock(&dev->object_name_lock);
 463                 ret = 0;
 464         }
 465
 466 err:
 467         drm_gem_object_unreference_unlocked(obj);
 468         return ret;
 469 }
 470
 471 /**
 472  * Open an object using the global name, returning a handle and the size.
 473  *
 474  * This handle (of course) holds a reference to the object, so the object
 475  * will not go away until the handle is deleted.
 476  */
 477 int
 478 drm_gem_open_ioctl(struct drm_device *dev, void *data,
 479                    struct drm_file *file_priv)
 480 {
 481         struct drm_gem_open *args = data;
 482         struct drm_gem_object *obj;
 483         int ret;
 484         u32 handle;
 485
 486         if (!(dev->driver->driver_features & DRIVER_GEM))
 487                 return -ENODEV;
 488
 489         spin_lock(&dev->object_name_lock);
 490         obj = idr_find(&dev->object_name_idr, (int) args->name);
 491         if (obj)
 492                 drm_gem_object_reference(obj);
 493         spin_unlock(&dev->object_name_lock);
 494         if (!obj)
 495                 return -ENOENT;
 496
 497         ret = drm_gem_handle_create(file_priv, obj, &handle);
 498         drm_gem_object_unreference_unlocked(obj);
 499         if (ret)
 500                 return ret;
 501
 502         args->handle = handle;
 503         args->size = obj->size;
 504
 505         return 0;
 506 }
 507
 508 /**
 509  * Called at device open time, sets up the structure for handling refcounting
 510  * of mm objects.
 511  */
 512 void
 513 drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
 514 {
 515         idr_init(&file_private->object_idr);
 516         spin_lock_init(&file_private->table_lock);
 517 }
 518
 519 /**
 520  * Called at device close to release the file's
 521  * handle references on objects.
 522  */
 523 static int
 524 drm_gem_object_release_handle(int id, void *ptr, void *data)
 525 {
 526         struct drm_file *file_priv = data;
 527         struct drm_gem_object *obj = ptr;
 528         struct drm_device *dev = obj->dev;
 529
 530         if (dev->driver->gem_close_object)
 531                 dev->driver->gem_close_object(obj, file_priv);
 532
 533         drm_gem_object_handle_unreference_unlocked(obj);
 534
 535         return 0;
 536 }
 537
 538 /**
 539  * Called at close time when the filp is going away.
 540  *
 541  * Releases any remaining references on objects by this filp.
 542  */
 543 void
 544 drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 545 {
 546         idr_for_each(&file_private->object_idr,
 547                      &drm_gem_object_release_handle, file_private);
 548
 549         idr_remove_all(&file_private->object_idr);
 550         idr_destroy(&file_private->object_idr);
 551 }
 552
 553 void
 554 drm_gem_object_release(struct drm_gem_object *obj)
 555 {
 556         if (obj->filp)
 557             fput(obj->filp);
 558 }
 559 EXPORT_SYMBOL(drm_gem_object_release);
 560
 561 /**
 562  * Called after the last reference to the object has been lost.
 563  * Must be called holding struct_ mutex
 564  *
 565  * Frees the object
 566  */
 567 void
 568 drm_gem_object_free(struct kref *kref)
 569 {
 570         struct drm_gem_object *obj = (struct drm_gem_object *) kref;
 571         struct drm_device *dev = obj->dev;
 572
 573         BUG_ON(!mutex_is_locked(&dev->struct_mutex));
 574
 575         if (dev->driver->gem_free_object != NULL)
 576                 dev->driver->gem_free_object(obj);
 577 }
 578 EXPORT_SYMBOL(drm_gem_object_free);
 579
 580 static void drm_gem_object_ref_bug(struct kref *list_kref)
 581 {
 582         BUG();
 583 }
 584
 585 /**
 586  * Called after the last handle to the object has been closed
 587  *
 588  * Removes any name for the object. Note that this must be
 589  * called before drm_gem_object_free or we'll be touching
 590  * freed memory
 591  */
 592 void drm_gem_object_handle_free(struct drm_gem_object *obj)
 593 {
 594         struct drm_device *dev = obj->dev;
 595
 596         /* Remove any name for this object */
 597         spin_lock(&dev->object_name_lock);
 598         if (obj->name) {
 599                 idr_remove(&dev->object_name_idr, obj->name);
 600                 obj->name = 0;
 601                 spin_unlock(&dev->object_name_lock);
 602                 /*
 603                  * The object name held a reference to this object, drop
 604                  * that now.
 605                 *
 606                 * This cannot be the last reference, since the handle holds one too.
 607                  */
 608                 kref_put(&obj->refcount, drm_gem_object_ref_bug);
 609         } else
 610                 spin_unlock(&dev->object_name_lock);
 611
 612 }
 613 EXPORT_SYMBOL(drm_gem_object_handle_free);
 614
 615 void drm_gem_vm_open(struct vm_area_struct *vma)
 616 {
 617         struct drm_gem_object *obj = vma->vm_private_data;
 618
 619         drm_gem_object_reference(obj);
 620
 621         mutex_lock(&obj->dev->struct_mutex);
 622         drm_vm_open_locked(vma);
 623         mutex_unlock(&obj->dev->struct_mutex);
 624 }
 625 EXPORT_SYMBOL(drm_gem_vm_open);
 626
 627 void drm_gem_vm_close(struct vm_area_struct *vma)
 628 {
 629         struct drm_gem_object *obj = vma->vm_private_data;
 630         struct drm_device *dev = obj->dev;
 631
 632         mutex_lock(&dev->struct_mutex);
 633         drm_vm_close_locked(vma);
 634         drm_gem_object_unreference(obj);
 635         mutex_unlock(&dev->struct_mutex);
 636 }
 637 EXPORT_SYMBOL(drm_gem_vm_close);
 638
 639
 640 /**
 641  * drm_gem_mmap - memory map routine for GEM objects
 642  * @filp: DRM file pointer
 643  * @vma: VMA for the area to be mapped
 644  *
 645  * If a driver supports GEM object mapping, mmap calls on the DRM file
 646  * descriptor will end up here.
 647  *
 648  * If we find the object based on the offset passed in (vma->vm_pgoff will
 649  * contain the fake offset we created when the GTT map ioctl was called on
 650  * the object), we set up the driver fault handler so that any accesses
 651  * to the object can be trapped, to perform migration, GTT binding, surface
 652  * register allocation, or performance monitoring.
 653  */
 654 int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 655 {
 656         struct drm_file *priv = filp->private_data;
 657         struct drm_device *dev = priv->minor->dev;
 658         struct drm_gem_mm *mm = dev->mm_private;
 659         struct drm_local_map *map = NULL;
 660         struct drm_gem_object *obj;
 661         struct drm_hash_item *hash;
 662         int ret = 0;
 663
 664         mutex_lock(&dev->struct_mutex);
 665
 666         if (drm_ht_find_item(&mm->offset_hash, vma->vm_pgoff, &hash)) {
 667                 mutex_unlock(&dev->struct_mutex);
 668                 return drm_mmap(filp, vma);
 669         }
 670
 671         map = drm_hash_entry(hash, struct drm_map_list, hash)->map;
 672         if (!map ||
 673             ((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN))) {
 674                 ret =  -EPERM;
 675                 goto out_unlock;
 676         }
 677
 678         /* Check for valid size. */
 679         if (map->size < vma->vm_end - vma->vm_start) {
 680                 ret = -EINVAL;
 681                 goto out_unlock;
 682         }
 683
 684         obj = map->handle;
 685         if (!obj->dev->driver->gem_vm_ops) {
 686                 ret = -EINVAL;
 687                 goto out_unlock;
 688         }
 689
 690         vma->vm_flags |= VM_RESERVED | VM_IO | VM_PFNMAP | VM_DONTEXPAND;
 691         vma->vm_ops = obj->dev->driver->gem_vm_ops;
 692         vma->vm_private_data = map->handle;
 693         vma->vm_page_prot =  pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
 694
 695         /* Take a ref for this mapping of the object, so that the fault
 696          * handler can dereference the mmap offset's pointer to the object.
 697          * This reference is cleaned up by the corresponding vm_close
 698          * (which should happen whether the vma was created by this call, or
 699          * by a vm_open due to mremap or partial unmap or whatever).
 700          */
 701         drm_gem_object_reference(obj);
 702
 703         vma->vm_file = filp;    /* Needed for drm_vm_open() */
 704         drm_vm_open_locked(vma);
 705
 706 out_unlock:
 707         mutex_unlock(&dev->struct_mutex);
 708
 709         return ret;
 710 }
 711 EXPORT_SYMBOL(drm_gem_mmap);