drivers/gpu/drm/ttm/ttm_object.c

   1 /**************************************************************************
   2  *
   3  * Copyright (c) 2009-2013 VMware, Inc., Palo Alto, CA., USA
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  21  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  22  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  23  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  24  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27 /*
  28  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  29  *
  30  * While no substantial code is shared, the prime code is inspired by
  31  * drm_prime.c, with
  32  * Authors:
  33  *      Dave Airlie <airlied@redhat.com>
  34  *      Rob Clark <rob.clark@linaro.org>
  35  */
  36 /** @file ttm_ref_object.c
  37  *
  38  * Base- and reference object implementation for the various
  39  * ttm objects. Implements reference counting, minimal security checks
  40  * and release on file close.
  41  */
  42
  43
  44 /**
  45  * struct ttm_object_file
  46  *
  47  * @tdev: Pointer to the ttm_object_device.
  48  *
  49  * @lock: Lock that protects the ref_list list and the
  50  * ref_hash hash tables.
  51  *
  52  * @ref_list: List of ttm_ref_objects to be destroyed at
  53  * file release.
  54  *
  55  * @ref_hash: Hash tables of ref objects, one per ttm_ref_type,
  56  * for fast lookup of ref objects given a base object.
  57  */
  58
  59 #define pr_fmt(fmt) "[TTM] " fmt
  60
  61 #include <drm/ttm/ttm_object.h>
  62 #include <drm/ttm/ttm_module.h>
  63 #include <linux/list.h>
  64 #include <linux/spinlock.h>
  65 #include <linux/slab.h>
  66 #include <linux/module.h>
  67 #include <linux/atomic.h>
  68
  69 struct ttm_object_file {
  70         struct ttm_object_device *tdev;
  71         rwlock_t lock;
  72         struct list_head ref_list;
  73         struct drm_open_hash ref_hash[TTM_REF_NUM];
  74         struct kref refcount;
  75 };
  76
  77 /**
  78  * struct ttm_object_device
  79  *
  80  * @object_lock: lock that protects the object_hash hash table.
  81  *
  82  * @object_hash: hash table for fast lookup of object global names.
  83  *
  84  * @object_count: Per device object count.
  85  *
  86  * This is the per-device data structure needed for ttm object management.
  87  */
  88
  89 struct ttm_object_device {
  90         spinlock_t object_lock;
  91         struct drm_open_hash object_hash;
  92         atomic_t object_count;
  93         struct ttm_mem_global *mem_glob;
  94         struct dma_buf_ops ops;
  95         void (*dmabuf_release)(struct dma_buf *dma_buf);
  96         size_t dma_buf_size;
  97 };
  98
  99 /**
 100  * struct ttm_ref_object
 101  *
 102  * @hash: Hash entry for the per-file object reference hash.
 103  *
 104  * @head: List entry for the per-file list of ref-objects.
 105  *
 106  * @kref: Ref count.
 107  *
 108  * @obj: Base object this ref object is referencing.
 109  *
 110  * @ref_type: Type of ref object.
 111  *
 112  * This is similar to an idr object, but it also has a hash table entry
 113  * that allows lookup with a pointer to the referenced object as a key. In
 114  * that way, one can easily detect whether a base object is referenced by
 115  * a particular ttm_object_file. It also carries a ref count to avoid creating
 116  * multiple ref objects if a ttm_object_file references the same base
 117  * object more than once.
 118  */
 119
 120 struct ttm_ref_object {
 121         struct drm_hash_item hash;
 122         struct list_head head;
 123         struct kref kref;
 124         enum ttm_ref_type ref_type;
 125         struct ttm_base_object *obj;
 126         struct ttm_object_file *tfile;
 127 };
 128
 129 static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf);
 130
 131 static inline struct ttm_object_file *
 132 ttm_object_file_ref(struct ttm_object_file *tfile)
 133 {
 134         kref_get(&tfile->refcount);
 135         return tfile;
 136 }
 137
 138 static void ttm_object_file_destroy(struct kref *kref)
 139 {
 140         struct ttm_object_file *tfile =
 141                 container_of(kref, struct ttm_object_file, refcount);
 142
 143         kfree(tfile);
 144 }
 145
 146
 147 static inline void ttm_object_file_unref(struct ttm_object_file **p_tfile)
 148 {
 149         struct ttm_object_file *tfile = *p_tfile;
 150
 151         *p_tfile = NULL;
 152         kref_put(&tfile->refcount, ttm_object_file_destroy);
 153 }
 154
 155
 156 int ttm_base_object_init(struct ttm_object_file *tfile,
 157                          struct ttm_base_object *base,
 158                          bool shareable,
 159                          enum ttm_object_type object_type,
 160                          void (*refcount_release) (struct ttm_base_object **),
 161                          void (*ref_obj_release) (struct ttm_base_object *,
 162                                                   enum ttm_ref_type ref_type))
 163 {
 164         struct ttm_object_device *tdev = tfile->tdev;
 165         int ret;
 166
 167         base->shareable = shareable;
 168         base->tfile = ttm_object_file_ref(tfile);
 169         base->refcount_release = refcount_release;
 170         base->ref_obj_release = ref_obj_release;
 171         base->object_type = object_type;
 172         kref_init(&base->refcount);
 173         spin_lock(&tdev->object_lock);
 174         ret = drm_ht_just_insert_please_rcu(&tdev->object_hash,
 175                                             &base->hash,
 176                                             (unsigned long)base, 31, 0, 0);
 177         spin_unlock(&tdev->object_lock);
 178         if (unlikely(ret != 0))
 179                 goto out_err0;
 180
 181         ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL);
 182         if (unlikely(ret != 0))
 183                 goto out_err1;
 184
 185         ttm_base_object_unref(&base);
 186
 187         return 0;
 188 out_err1:
 189         spin_lock(&tdev->object_lock);
 190         (void)drm_ht_remove_item_rcu(&tdev->object_hash, &base->hash);
 191         spin_unlock(&tdev->object_lock);
 192 out_err0:
 193         return ret;
 194 }
 195 EXPORT_SYMBOL(ttm_base_object_init);
 196
 197 static void ttm_release_base(struct kref *kref)
 198 {
 199         struct ttm_base_object *base =
 200             container_of(kref, struct ttm_base_object, refcount);
 201         struct ttm_object_device *tdev = base->tfile->tdev;
 202
 203         spin_lock(&tdev->object_lock);
 204         (void)drm_ht_remove_item_rcu(&tdev->object_hash, &base->hash);
 205         spin_unlock(&tdev->object_lock);
 206
 207         /*
 208          * Note: We don't use synchronize_rcu() here because it's far
 209          * too slow. It's up to the user to free the object using
 210          * call_rcu() or ttm_base_object_kfree().
 211          */
 212
 213         if (base->refcount_release) {
 214                 ttm_object_file_unref(&base->tfile);
 215                 base->refcount_release(&base);
 216         }
 217 }
 218
 219 void ttm_base_object_unref(struct ttm_base_object **p_base)
 220 {
 221         struct ttm_base_object *base = *p_base;
 222
 223         *p_base = NULL;
 224
 225         kref_put(&base->refcount, ttm_release_base);
 226 }
 227 EXPORT_SYMBOL(ttm_base_object_unref);
 228
 229 struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile,
 230                                                uint32_t key)
 231 {
 232         struct ttm_object_device *tdev = tfile->tdev;
 233         struct ttm_base_object *uninitialized_var(base);
 234         struct drm_hash_item *hash;
 235         int ret;
 236
 237         rcu_read_lock();
 238         ret = drm_ht_find_item_rcu(&tdev->object_hash, key, &hash);
 239
 240         if (likely(ret == 0)) {
 241                 base = drm_hash_entry(hash, struct ttm_base_object, hash);
 242                 ret = kref_get_unless_zero(&base->refcount) ? 0 : -EINVAL;
 243         }
 244         rcu_read_unlock();
 245
 246         if (unlikely(ret != 0))
 247                 return NULL;
 248
 249         if (tfile != base->tfile && !base->shareable) {
 250                 pr_err("Attempted access of non-shareable object\n");
 251                 ttm_base_object_unref(&base);
 252                 return NULL;
 253         }
 254
 255         return base;
 256 }
 257 EXPORT_SYMBOL(ttm_base_object_lookup);
 258
 259 int ttm_ref_object_add(struct ttm_object_file *tfile,
 260                        struct ttm_base_object *base,
 261                        enum ttm_ref_type ref_type, bool *existed)
 262 {
 263         struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
 264         struct ttm_ref_object *ref;
 265         struct drm_hash_item *hash;
 266         struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;
 267         int ret = -EINVAL;
 268
 269         if (existed != NULL)
 270                 *existed = true;
 271
 272         while (ret == -EINVAL) {
 273                 read_lock(&tfile->lock);
 274                 ret = drm_ht_find_item(ht, base->hash.key, &hash);
 275
 276                 if (ret == 0) {
 277                         ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
 278                         kref_get(&ref->kref);
 279                         read_unlock(&tfile->lock);
 280                         break;
 281                 }
 282
 283                 read_unlock(&tfile->lock);
 284                 ret = ttm_mem_global_alloc(mem_glob, sizeof(*ref),
 285                                            false, false);
 286                 if (unlikely(ret != 0))
 287                         return ret;
 288                 ref = kmalloc(sizeof(*ref), GFP_KERNEL);
 289                 if (unlikely(ref == NULL)) {
 290                         ttm_mem_global_free(mem_glob, sizeof(*ref));
 291                         return -ENOMEM;
 292                 }
 293
 294                 ref->hash.key = base->hash.key;
 295                 ref->obj = base;
 296                 ref->tfile = tfile;
 297                 ref->ref_type = ref_type;
 298                 kref_init(&ref->kref);
 299
 300                 write_lock(&tfile->lock);
 301                 ret = drm_ht_insert_item(ht, &ref->hash);
 302
 303                 if (likely(ret == 0)) {
 304                         list_add_tail(&ref->head, &tfile->ref_list);
 305                         kref_get(&base->refcount);
 306                         write_unlock(&tfile->lock);
 307                         if (existed != NULL)
 308                                 *existed = false;
 309                         break;
 310                 }
 311
 312                 write_unlock(&tfile->lock);
 313                 BUG_ON(ret != -EINVAL);
 314
 315                 ttm_mem_global_free(mem_glob, sizeof(*ref));
 316                 kfree(ref);
 317         }
 318
 319         return ret;
 320 }
 321 EXPORT_SYMBOL(ttm_ref_object_add);
 322
 323 static void ttm_ref_object_release(struct kref *kref)
 324 {
 325         struct ttm_ref_object *ref =
 326             container_of(kref, struct ttm_ref_object, kref);
 327         struct ttm_base_object *base = ref->obj;
 328         struct ttm_object_file *tfile = ref->tfile;
 329         struct drm_open_hash *ht;
 330         struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;
 331
 332         ht = &tfile->ref_hash[ref->ref_type];
 333         (void)drm_ht_remove_item(ht, &ref->hash);
 334         list_del(&ref->head);
 335         write_unlock(&tfile->lock);
 336
 337         if (ref->ref_type != TTM_REF_USAGE && base->ref_obj_release)
 338                 base->ref_obj_release(base, ref->ref_type);
 339
 340         ttm_base_object_unref(&ref->obj);
 341         ttm_mem_global_free(mem_glob, sizeof(*ref));
 342         kfree(ref);
 343         write_lock(&tfile->lock);
 344 }
 345
 346 int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
 347                               unsigned long key, enum ttm_ref_type ref_type)
 348 {
 349         struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
 350         struct ttm_ref_object *ref;
 351         struct drm_hash_item *hash;
 352         int ret;
 353
 354         write_lock(&tfile->lock);
 355         ret = drm_ht_find_item(ht, key, &hash);
 356         if (unlikely(ret != 0)) {
 357                 write_unlock(&tfile->lock);
 358                 return -EINVAL;
 359         }
 360         ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
 361         kref_put(&ref->kref, ttm_ref_object_release);
 362         write_unlock(&tfile->lock);
 363         return 0;
 364 }
 365 EXPORT_SYMBOL(ttm_ref_object_base_unref);
 366
 367 void ttm_object_file_release(struct ttm_object_file **p_tfile)
 368 {
 369         struct ttm_ref_object *ref;
 370         struct list_head *list;
 371         unsigned int i;
 372         struct ttm_object_file *tfile = *p_tfile;
 373
 374         *p_tfile = NULL;
 375         write_lock(&tfile->lock);
 376
 377         /*
 378          * Since we release the lock within the loop, we have to
 379          * restart it from the beginning each time.
 380          */
 381
 382         while (!list_empty(&tfile->ref_list)) {
 383                 list = tfile->ref_list.next;
 384                 ref = list_entry(list, struct ttm_ref_object, head);
 385                 ttm_ref_object_release(&ref->kref);
 386         }
 387
 388         for (i = 0; i < TTM_REF_NUM; ++i)
 389                 drm_ht_remove(&tfile->ref_hash[i]);
 390
 391         write_unlock(&tfile->lock);
 392         ttm_object_file_unref(&tfile);
 393 }
 394 EXPORT_SYMBOL(ttm_object_file_release);
 395
 396 struct ttm_object_file *ttm_object_file_init(struct ttm_object_device *tdev,
 397                                              unsigned int hash_order)
 398 {
 399         struct ttm_object_file *tfile = kmalloc(sizeof(*tfile), GFP_KERNEL);
 400         unsigned int i;
 401         unsigned int j = 0;
 402         int ret;
 403
 404         if (unlikely(tfile == NULL))
 405                 return NULL;
 406
 407         rwlock_init(&tfile->lock);
 408         tfile->tdev = tdev;
 409         kref_init(&tfile->refcount);
 410         INIT_LIST_HEAD(&tfile->ref_list);
 411
 412         for (i = 0; i < TTM_REF_NUM; ++i) {
 413                 ret = drm_ht_create(&tfile->ref_hash[i], hash_order);
 414                 if (ret) {
 415                         j = i;
 416                         goto out_err;
 417                 }
 418         }
 419
 420         return tfile;
 421 out_err:
 422         for (i = 0; i < j; ++i)
 423                 drm_ht_remove(&tfile->ref_hash[i]);
 424
 425         kfree(tfile);
 426
 427         return NULL;
 428 }
 429 EXPORT_SYMBOL(ttm_object_file_init);
 430
 431 struct ttm_object_device *
 432 ttm_object_device_init(struct ttm_mem_global *mem_glob,
 433                        unsigned int hash_order,
 434                        const struct dma_buf_ops *ops)
 435 {
 436         struct ttm_object_device *tdev = kmalloc(sizeof(*tdev), GFP_KERNEL);
 437         int ret;
 438
 439         if (unlikely(tdev == NULL))
 440                 return NULL;
 441
 442         tdev->mem_glob = mem_glob;
 443         spin_lock_init(&tdev->object_lock);
 444         atomic_set(&tdev->object_count, 0);
 445         ret = drm_ht_create(&tdev->object_hash, hash_order);
 446         if (ret != 0)
 447                 goto out_no_object_hash;
 448
 449         tdev->ops = *ops;
 450         tdev->dmabuf_release = tdev->ops.release;
 451         tdev->ops.release = ttm_prime_dmabuf_release;
 452         tdev->dma_buf_size = ttm_round_pot(sizeof(struct dma_buf)) +
 453                 ttm_round_pot(sizeof(struct file));
 454         return tdev;
 455
 456 out_no_object_hash:
 457         kfree(tdev);
 458         return NULL;
 459 }
 460 EXPORT_SYMBOL(ttm_object_device_init);
 461
 462 void ttm_object_device_release(struct ttm_object_device **p_tdev)
 463 {
 464         struct ttm_object_device *tdev = *p_tdev;
 465
 466         *p_tdev = NULL;
 467
 468         spin_lock(&tdev->object_lock);
 469         drm_ht_remove(&tdev->object_hash);
 470         spin_unlock(&tdev->object_lock);
 471
 472         kfree(tdev);
 473 }
 474 EXPORT_SYMBOL(ttm_object_device_release);
 475
 476 /**
 477  * get_dma_buf_unless_doomed - get a dma_buf reference if possible.
 478  *
 479  * @dma_buf: Non-refcounted pointer to a struct dma-buf.
 480  *
 481  * Obtain a file reference from a lookup structure that doesn't refcount
 482  * the file, but synchronizes with its release method to make sure it has
 483  * not been freed yet. See for example kref_get_unless_zero documentation.
 484  * Returns true if refcounting succeeds, false otherwise.
 485  *
 486  * Nobody really wants this as a public API yet, so let it mature here
 487  * for some time...
 488  */
 489 static bool __must_check get_dma_buf_unless_doomed(struct dma_buf *dmabuf)
 490 {
 491         return atomic_long_inc_not_zero(&dmabuf->file->f_count) != 0L;
 492 }
 493
 494 /**
 495  * ttm_prime_refcount_release - refcount release method for a prime object.
 496  *
 497  * @p_base: Pointer to ttm_base_object pointer.
 498  *
 499  * This is a wrapper that calls the refcount_release founction of the
 500  * underlying object. At the same time it cleans up the prime object.
 501  * This function is called when all references to the base object we
 502  * derive from are gone.
 503  */
 504 static void ttm_prime_refcount_release(struct ttm_base_object **p_base)
 505 {
 506         struct ttm_base_object *base = *p_base;
 507         struct ttm_prime_object *prime;
 508
 509         *p_base = NULL;
 510         prime = container_of(base, struct ttm_prime_object, base);
 511         BUG_ON(prime->dma_buf != NULL);
 512         mutex_destroy(&prime->mutex);
 513         if (prime->refcount_release)
 514                 prime->refcount_release(&base);
 515 }
 516
 517 /**
 518  * ttm_prime_dmabuf_release - Release method for the dma-bufs we export
 519  *
 520  * @dma_buf:
 521  *
 522  * This function first calls the dma_buf release method the driver
 523  * provides. Then it cleans up our dma_buf pointer used for lookup,
 524  * and finally releases the reference the dma_buf has on our base
 525  * object.
 526  */
 527 static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf)
 528 {
 529         struct ttm_prime_object *prime =
 530                 (struct ttm_prime_object *) dma_buf->priv;
 531         struct ttm_base_object *base = &prime->base;
 532         struct ttm_object_device *tdev = base->tfile->tdev;
 533
 534         if (tdev->dmabuf_release)
 535                 tdev->dmabuf_release(dma_buf);
 536         mutex_lock(&prime->mutex);
 537         if (prime->dma_buf == dma_buf)
 538                 prime->dma_buf = NULL;
 539         mutex_unlock(&prime->mutex);
 540         ttm_mem_global_free(tdev->mem_glob, tdev->dma_buf_size);
 541         ttm_base_object_unref(&base);
 542 }
 543
 544 /**
 545  * ttm_prime_fd_to_handle - Get a base object handle from a prime fd
 546  *
 547  * @tfile: A struct ttm_object_file identifying the caller.
 548  * @fd: The prime / dmabuf fd.
 549  * @handle: The returned handle.
 550  *
 551  * This function returns a handle to an object that previously exported
 552  * a dma-buf. Note that we don't handle imports yet, because we simply
 553  * have no consumers of that implementation.
 554  */
 555 int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
 556                            int fd, u32 *handle)
 557 {
 558         struct ttm_object_device *tdev = tfile->tdev;
 559         struct dma_buf *dma_buf;
 560         struct ttm_prime_object *prime;
 561         struct ttm_base_object *base;
 562         int ret;
 563
 564         dma_buf = dma_buf_get(fd);
 565         if (IS_ERR(dma_buf))
 566                 return PTR_ERR(dma_buf);
 567
 568         if (dma_buf->ops != &tdev->ops)
 569                 return -ENOSYS;
 570
 571         prime = (struct ttm_prime_object *) dma_buf->priv;
 572         base = &prime->base;
 573         *handle = base->hash.key;
 574         ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL);
 575
 576         dma_buf_put(dma_buf);
 577
 578         return ret;
 579 }
 580 EXPORT_SYMBOL_GPL(ttm_prime_fd_to_handle);
 581
 582 /**
 583  * ttm_prime_handle_to_fd - Return a dma_buf fd from a ttm prime object
 584  *
 585  * @tfile: Struct ttm_object_file identifying the caller.
 586  * @handle: Handle to the object we're exporting from.
 587  * @flags: flags for dma-buf creation. We just pass them on.
 588  * @prime_fd: The returned file descriptor.
 589  *
 590  */
 591 int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
 592                            uint32_t handle, uint32_t flags,
 593                            int *prime_fd)
 594 {
 595         struct ttm_object_device *tdev = tfile->tdev;
 596         struct ttm_base_object *base;
 597         struct dma_buf *dma_buf;
 598         struct ttm_prime_object *prime;
 599         int ret;
 600
 601         base = ttm_base_object_lookup(tfile, handle);
 602         if (unlikely(base == NULL ||
 603                      base->object_type != ttm_prime_type)) {
 604                 ret = -ENOENT;
 605                 goto out_unref;
 606         }
 607
 608         prime = container_of(base, struct ttm_prime_object, base);
 609         if (unlikely(!base->shareable)) {
 610                 ret = -EPERM;
 611                 goto out_unref;
 612         }
 613
 614         ret = mutex_lock_interruptible(&prime->mutex);
 615         if (unlikely(ret != 0)) {
 616                 ret = -ERESTARTSYS;
 617                 goto out_unref;
 618         }
 619
 620         dma_buf = prime->dma_buf;
 621         if (!dma_buf || !get_dma_buf_unless_doomed(dma_buf)) {
 622
 623                 /*
 624                  * Need to create a new dma_buf, with memory accounting.
 625                  */
 626                 ret = ttm_mem_global_alloc(tdev->mem_glob, tdev->dma_buf_size,
 627                                            false, true);
 628                 if (unlikely(ret != 0)) {
 629                         mutex_unlock(&prime->mutex);
 630                         goto out_unref;
 631                 }
 632
 633                 dma_buf = dma_buf_export(prime, &tdev->ops,
 634                                          prime->size, flags);
 635                 if (IS_ERR(dma_buf)) {
 636                         ret = PTR_ERR(dma_buf);
 637                         ttm_mem_global_free(tdev->mem_glob,
 638                                             tdev->dma_buf_size);
 639                         mutex_unlock(&prime->mutex);
 640                         goto out_unref;
 641                 }
 642
 643                 /*
 644                  * dma_buf has taken the base object reference
 645                  */
 646                 base = NULL;
 647                 prime->dma_buf = dma_buf;
 648         }
 649         mutex_unlock(&prime->mutex);
 650
 651         ret = dma_buf_fd(dma_buf, flags);
 652         if (ret >= 0) {
 653                 *prime_fd = ret;
 654                 ret = 0;
 655         } else
 656                 dma_buf_put(dma_buf);
 657
 658 out_unref:
 659         if (base)
 660                 ttm_base_object_unref(&base);
 661         return ret;
 662 }
 663 EXPORT_SYMBOL_GPL(ttm_prime_handle_to_fd);
 664
 665 /**
 666  * ttm_prime_object_init - Initialize a ttm_prime_object
 667  *
 668  * @tfile: struct ttm_object_file identifying the caller
 669  * @size: The size of the dma_bufs we export.
 670  * @prime: The object to be initialized.
 671  * @shareable: See ttm_base_object_init
 672  * @type: See ttm_base_object_init
 673  * @refcount_release: See ttm_base_object_init
 674  * @ref_obj_release: See ttm_base_object_init
 675  *
 676  * Initializes an object which is compatible with the drm_prime model
 677  * for data sharing between processes and devices.
 678  */
 679 int ttm_prime_object_init(struct ttm_object_file *tfile, size_t size,
 680                           struct ttm_prime_object *prime, bool shareable,
 681                           enum ttm_object_type type,
 682                           void (*refcount_release) (struct ttm_base_object **),
 683                           void (*ref_obj_release) (struct ttm_base_object *,
 684                                                    enum ttm_ref_type ref_type))
 685 {
 686         mutex_init(&prime->mutex);
 687         prime->size = PAGE_ALIGN(size);
 688         prime->real_type = type;
 689         prime->dma_buf = NULL;
 690         prime->refcount_release = refcount_release;
 691         return ttm_base_object_init(tfile, &prime->base, shareable,
 692                                     ttm_prime_type,
 693                                     ttm_prime_refcount_release,
 694                                     ref_obj_release);
 695 }
 696 EXPORT_SYMBOL(ttm_prime_object_init);