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         spinlock_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 rcu_head rcu_head;
 122         struct drm_hash_item hash;
 123         struct list_head head;
 124         struct kref kref;
 125         enum ttm_ref_type ref_type;
 126         struct ttm_base_object *obj;
 127         struct ttm_object_file *tfile;
 128 };
 129
 130 static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf);
 131
 132 static inline struct ttm_object_file *
 133 ttm_object_file_ref(struct ttm_object_file *tfile)
 134 {
 135         kref_get(&tfile->refcount);
 136         return tfile;
 137 }
 138
 139 static void ttm_object_file_destroy(struct kref *kref)
 140 {
 141         struct ttm_object_file *tfile =
 142                 container_of(kref, struct ttm_object_file, refcount);
 143
 144         kfree(tfile);
 145 }
 146
 147
 148 static inline void ttm_object_file_unref(struct ttm_object_file **p_tfile)
 149 {
 150         struct ttm_object_file *tfile = *p_tfile;
 151
 152         *p_tfile = NULL;
 153         kref_put(&tfile->refcount, ttm_object_file_destroy);
 154 }
 155
 156
 157 int ttm_base_object_init(struct ttm_object_file *tfile,
 158                          struct ttm_base_object *base,
 159                          bool shareable,
 160                          enum ttm_object_type object_type,
 161                          void (*refcount_release) (struct ttm_base_object **),
 162                          void (*ref_obj_release) (struct ttm_base_object *,
 163                                                   enum ttm_ref_type ref_type))
 164 {
 165         struct ttm_object_device *tdev = tfile->tdev;
 166         int ret;
 167
 168         base->shareable = shareable;
 169         base->tfile = ttm_object_file_ref(tfile);
 170         base->refcount_release = refcount_release;
 171         base->ref_obj_release = ref_obj_release;
 172         base->object_type = object_type;
 173         kref_init(&base->refcount);
 174         spin_lock(&tdev->object_lock);
 175         ret = drm_ht_just_insert_please_rcu(&tdev->object_hash,
 176                                             &base->hash,
 177                                             (unsigned long)base, 31, 0, 0);
 178         spin_unlock(&tdev->object_lock);
 179         if (unlikely(ret != 0))
 180                 goto out_err0;
 181
 182         ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL, false);
 183         if (unlikely(ret != 0))
 184                 goto out_err1;
 185
 186         ttm_base_object_unref(&base);
 187
 188         return 0;
 189 out_err1:
 190         spin_lock(&tdev->object_lock);
 191         (void)drm_ht_remove_item_rcu(&tdev->object_hash, &base->hash);
 192         spin_unlock(&tdev->object_lock);
 193 out_err0:
 194         return ret;
 195 }
 196 EXPORT_SYMBOL(ttm_base_object_init);
 197
 198 static void ttm_release_base(struct kref *kref)
 199 {
 200         struct ttm_base_object *base =
 201             container_of(kref, struct ttm_base_object, refcount);
 202         struct ttm_object_device *tdev = base->tfile->tdev;
 203
 204         spin_lock(&tdev->object_lock);
 205         (void)drm_ht_remove_item_rcu(&tdev->object_hash, &base->hash);
 206         spin_unlock(&tdev->object_lock);
 207
 208         /*
 209          * Note: We don't use synchronize_rcu() here because it's far
 210          * too slow. It's up to the user to free the object using
 211          * call_rcu() or ttm_base_object_kfree().
 212          */
 213
 214         ttm_object_file_unref(&base->tfile);
 215         if (base->refcount_release)
 216                 base->refcount_release(&base);
 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_base_object *base = NULL;
 233         struct drm_hash_item *hash;
 234         struct drm_open_hash *ht = &tfile->ref_hash[TTM_REF_USAGE];
 235         int ret;
 236
 237         rcu_read_lock();
 238         ret = drm_ht_find_item_rcu(ht, key, &hash);
 239
 240         if (likely(ret == 0)) {
 241                 base = drm_hash_entry(hash, struct ttm_ref_object, hash)->obj;
 242                 if (!kref_get_unless_zero(&base->refcount))
 243                         base = NULL;
 244         }
 245         rcu_read_unlock();
 246
 247         return base;
 248 }
 249 EXPORT_SYMBOL(ttm_base_object_lookup);
 250
 251 struct ttm_base_object *
 252 ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key)
 253 {
 254         struct ttm_base_object *base = NULL;
 255         struct drm_hash_item *hash;
 256         struct drm_open_hash *ht = &tdev->object_hash;
 257         int ret;
 258
 259         rcu_read_lock();
 260         ret = drm_ht_find_item_rcu(ht, key, &hash);
 261
 262         if (likely(ret == 0)) {
 263                 base = drm_hash_entry(hash, struct ttm_base_object, hash);
 264                 if (!kref_get_unless_zero(&base->refcount))
 265                         base = NULL;
 266         }
 267         rcu_read_unlock();
 268
 269         return base;
 270 }
 271 EXPORT_SYMBOL(ttm_base_object_lookup_for_ref);
 272
 273 /**
 274  * ttm_ref_object_exists - Check whether a caller has a valid ref object
 275  * (has opened) a base object.
 276  *
 277  * @tfile: Pointer to a struct ttm_object_file identifying the caller.
 278  * @base: Pointer to a struct base object.
 279  *
 280  * Checks wether the caller identified by @tfile has put a valid USAGE
 281  * reference object on the base object identified by @base.
 282  */
 283 bool ttm_ref_object_exists(struct ttm_object_file *tfile,
 284                            struct ttm_base_object *base)
 285 {
 286         struct drm_open_hash *ht = &tfile->ref_hash[TTM_REF_USAGE];
 287         struct drm_hash_item *hash;
 288         struct ttm_ref_object *ref;
 289
 290         rcu_read_lock();
 291         if (unlikely(drm_ht_find_item_rcu(ht, base->hash.key, &hash) != 0))
 292                 goto out_false;
 293
 294         /*
 295          * Verify that the ref object is really pointing to our base object.
 296          * Our base object could actually be dead, and the ref object pointing
 297          * to another base object with the same handle.
 298          */
 299         ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
 300         if (unlikely(base != ref->obj))
 301                 goto out_false;
 302
 303         /*
 304          * Verify that the ref->obj pointer was actually valid!
 305          */
 306         rmb();
 307         if (unlikely(kref_read(&ref->kref) == 0))
 308                 goto out_false;
 309
 310         rcu_read_unlock();
 311         return true;
 312
 313  out_false:
 314         rcu_read_unlock();
 315         return false;
 316 }
 317 EXPORT_SYMBOL(ttm_ref_object_exists);
 318
 319 int ttm_ref_object_add(struct ttm_object_file *tfile,
 320                        struct ttm_base_object *base,
 321                        enum ttm_ref_type ref_type, bool *existed,
 322                        bool require_existed)
 323 {
 324         struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
 325         struct ttm_ref_object *ref;
 326         struct drm_hash_item *hash;
 327         struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;
 328         int ret = -EINVAL;
 329
 330         if (base->tfile != tfile && !base->shareable)
 331                 return -EPERM;
 332
 333         if (existed != NULL)
 334                 *existed = true;
 335
 336         while (ret == -EINVAL) {
 337                 rcu_read_lock();
 338                 ret = drm_ht_find_item_rcu(ht, base->hash.key, &hash);
 339
 340                 if (ret == 0) {
 341                         ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
 342                         if (kref_get_unless_zero(&ref->kref)) {
 343                                 rcu_read_unlock();
 344                                 break;
 345                         }
 346                 }
 347
 348                 rcu_read_unlock();
 349                 if (require_existed)
 350                         return -EPERM;
 351
 352                 ret = ttm_mem_global_alloc(mem_glob, sizeof(*ref),
 353                                            false, false);
 354                 if (unlikely(ret != 0))
 355                         return ret;
 356                 ref = kmalloc(sizeof(*ref), GFP_KERNEL);
 357                 if (unlikely(ref == NULL)) {
 358                         ttm_mem_global_free(mem_glob, sizeof(*ref));
 359                         return -ENOMEM;
 360                 }
 361
 362                 ref->hash.key = base->hash.key;
 363                 ref->obj = base;
 364                 ref->tfile = tfile;
 365                 ref->ref_type = ref_type;
 366                 kref_init(&ref->kref);
 367
 368                 spin_lock(&tfile->lock);
 369                 ret = drm_ht_insert_item_rcu(ht, &ref->hash);
 370
 371                 if (likely(ret == 0)) {
 372                         list_add_tail(&ref->head, &tfile->ref_list);
 373                         kref_get(&base->refcount);
 374                         spin_unlock(&tfile->lock);
 375                         if (existed != NULL)
 376                                 *existed = false;
 377                         break;
 378                 }
 379
 380                 spin_unlock(&tfile->lock);
 381                 BUG_ON(ret != -EINVAL);
 382
 383                 ttm_mem_global_free(mem_glob, sizeof(*ref));
 384                 kfree(ref);
 385         }
 386
 387         return ret;
 388 }
 389 EXPORT_SYMBOL(ttm_ref_object_add);
 390
 391 static void ttm_ref_object_release(struct kref *kref)
 392 {
 393         struct ttm_ref_object *ref =
 394             container_of(kref, struct ttm_ref_object, kref);
 395         struct ttm_base_object *base = ref->obj;
 396         struct ttm_object_file *tfile = ref->tfile;
 397         struct drm_open_hash *ht;
 398         struct ttm_mem_global *mem_glob = tfile->tdev->mem_glob;
 399
 400         ht = &tfile->ref_hash[ref->ref_type];
 401         (void)drm_ht_remove_item_rcu(ht, &ref->hash);
 402         list_del(&ref->head);
 403         spin_unlock(&tfile->lock);
 404
 405         if (ref->ref_type != TTM_REF_USAGE && base->ref_obj_release)
 406                 base->ref_obj_release(base, ref->ref_type);
 407
 408         ttm_base_object_unref(&ref->obj);
 409         ttm_mem_global_free(mem_glob, sizeof(*ref));
 410         kfree_rcu(ref, rcu_head);
 411         spin_lock(&tfile->lock);
 412 }
 413
 414 int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
 415                               unsigned long key, enum ttm_ref_type ref_type)
 416 {
 417         struct drm_open_hash *ht = &tfile->ref_hash[ref_type];
 418         struct ttm_ref_object *ref;
 419         struct drm_hash_item *hash;
 420         int ret;
 421
 422         spin_lock(&tfile->lock);
 423         ret = drm_ht_find_item(ht, key, &hash);
 424         if (unlikely(ret != 0)) {
 425                 spin_unlock(&tfile->lock);
 426                 return -EINVAL;
 427         }
 428         ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
 429         kref_put(&ref->kref, ttm_ref_object_release);
 430         spin_unlock(&tfile->lock);
 431         return 0;
 432 }
 433 EXPORT_SYMBOL(ttm_ref_object_base_unref);
 434
 435 void ttm_object_file_release(struct ttm_object_file **p_tfile)
 436 {
 437         struct ttm_ref_object *ref;
 438         struct list_head *list;
 439         unsigned int i;
 440         struct ttm_object_file *tfile = *p_tfile;
 441
 442         *p_tfile = NULL;
 443         spin_lock(&tfile->lock);
 444
 445         /*
 446          * Since we release the lock within the loop, we have to
 447          * restart it from the beginning each time.
 448          */
 449
 450         while (!list_empty(&tfile->ref_list)) {
 451                 list = tfile->ref_list.next;
 452                 ref = list_entry(list, struct ttm_ref_object, head);
 453                 ttm_ref_object_release(&ref->kref);
 454         }
 455
 456         spin_unlock(&tfile->lock);
 457         for (i = 0; i < TTM_REF_NUM; ++i)
 458                 drm_ht_remove(&tfile->ref_hash[i]);
 459
 460         ttm_object_file_unref(&tfile);
 461 }
 462 EXPORT_SYMBOL(ttm_object_file_release);
 463
 464 struct ttm_object_file *ttm_object_file_init(struct ttm_object_device *tdev,
 465                                              unsigned int hash_order)
 466 {
 467         struct ttm_object_file *tfile = kmalloc(sizeof(*tfile), GFP_KERNEL);
 468         unsigned int i;
 469         unsigned int j = 0;
 470         int ret;
 471
 472         if (unlikely(tfile == NULL))
 473                 return NULL;
 474
 475         spin_lock_init(&tfile->lock);
 476         tfile->tdev = tdev;
 477         kref_init(&tfile->refcount);
 478         INIT_LIST_HEAD(&tfile->ref_list);
 479
 480         for (i = 0; i < TTM_REF_NUM; ++i) {
 481                 ret = drm_ht_create(&tfile->ref_hash[i], hash_order);
 482                 if (ret) {
 483                         j = i;
 484                         goto out_err;
 485                 }
 486         }
 487
 488         return tfile;
 489 out_err:
 490         for (i = 0; i < j; ++i)
 491                 drm_ht_remove(&tfile->ref_hash[i]);
 492
 493         kfree(tfile);
 494
 495         return NULL;
 496 }
 497 EXPORT_SYMBOL(ttm_object_file_init);
 498
 499 struct ttm_object_device *
 500 ttm_object_device_init(struct ttm_mem_global *mem_glob,
 501                        unsigned int hash_order,
 502                        const struct dma_buf_ops *ops)
 503 {
 504         struct ttm_object_device *tdev = kmalloc(sizeof(*tdev), GFP_KERNEL);
 505         int ret;
 506
 507         if (unlikely(tdev == NULL))
 508                 return NULL;
 509
 510         tdev->mem_glob = mem_glob;
 511         spin_lock_init(&tdev->object_lock);
 512         atomic_set(&tdev->object_count, 0);
 513         ret = drm_ht_create(&tdev->object_hash, hash_order);
 514         if (ret != 0)
 515                 goto out_no_object_hash;
 516
 517         tdev->ops = *ops;
 518         tdev->dmabuf_release = tdev->ops.release;
 519         tdev->ops.release = ttm_prime_dmabuf_release;
 520         tdev->dma_buf_size = ttm_round_pot(sizeof(struct dma_buf)) +
 521                 ttm_round_pot(sizeof(struct file));
 522         return tdev;
 523
 524 out_no_object_hash:
 525         kfree(tdev);
 526         return NULL;
 527 }
 528 EXPORT_SYMBOL(ttm_object_device_init);
 529
 530 void ttm_object_device_release(struct ttm_object_device **p_tdev)
 531 {
 532         struct ttm_object_device *tdev = *p_tdev;
 533
 534         *p_tdev = NULL;
 535
 536         drm_ht_remove(&tdev->object_hash);
 537
 538         kfree(tdev);
 539 }
 540 EXPORT_SYMBOL(ttm_object_device_release);
 541
 542 /**
 543  * get_dma_buf_unless_doomed - get a dma_buf reference if possible.
 544  *
 545  * @dma_buf: Non-refcounted pointer to a struct dma-buf.
 546  *
 547  * Obtain a file reference from a lookup structure that doesn't refcount
 548  * the file, but synchronizes with its release method to make sure it has
 549  * not been freed yet. See for example kref_get_unless_zero documentation.
 550  * Returns true if refcounting succeeds, false otherwise.
 551  *
 552  * Nobody really wants this as a public API yet, so let it mature here
 553  * for some time...
 554  */
 555 static bool __must_check get_dma_buf_unless_doomed(struct dma_buf *dmabuf)
 556 {
 557         return atomic_long_inc_not_zero(&dmabuf->file->f_count) != 0L;
 558 }
 559
 560 /**
 561  * ttm_prime_refcount_release - refcount release method for a prime object.
 562  *
 563  * @p_base: Pointer to ttm_base_object pointer.
 564  *
 565  * This is a wrapper that calls the refcount_release founction of the
 566  * underlying object. At the same time it cleans up the prime object.
 567  * This function is called when all references to the base object we
 568  * derive from are gone.
 569  */
 570 static void ttm_prime_refcount_release(struct ttm_base_object **p_base)
 571 {
 572         struct ttm_base_object *base = *p_base;
 573         struct ttm_prime_object *prime;
 574
 575         *p_base = NULL;
 576         prime = container_of(base, struct ttm_prime_object, base);
 577         BUG_ON(prime->dma_buf != NULL);
 578         mutex_destroy(&prime->mutex);
 579         if (prime->refcount_release)
 580                 prime->refcount_release(&base);
 581 }
 582
 583 /**
 584  * ttm_prime_dmabuf_release - Release method for the dma-bufs we export
 585  *
 586  * @dma_buf:
 587  *
 588  * This function first calls the dma_buf release method the driver
 589  * provides. Then it cleans up our dma_buf pointer used for lookup,
 590  * and finally releases the reference the dma_buf has on our base
 591  * object.
 592  */
 593 static void ttm_prime_dmabuf_release(struct dma_buf *dma_buf)
 594 {
 595         struct ttm_prime_object *prime =
 596                 (struct ttm_prime_object *) dma_buf->priv;
 597         struct ttm_base_object *base = &prime->base;
 598         struct ttm_object_device *tdev = base->tfile->tdev;
 599
 600         if (tdev->dmabuf_release)
 601                 tdev->dmabuf_release(dma_buf);
 602         mutex_lock(&prime->mutex);
 603         if (prime->dma_buf == dma_buf)
 604                 prime->dma_buf = NULL;
 605         mutex_unlock(&prime->mutex);
 606         ttm_mem_global_free(tdev->mem_glob, tdev->dma_buf_size);
 607         ttm_base_object_unref(&base);
 608 }
 609
 610 /**
 611  * ttm_prime_fd_to_handle - Get a base object handle from a prime fd
 612  *
 613  * @tfile: A struct ttm_object_file identifying the caller.
 614  * @fd: The prime / dmabuf fd.
 615  * @handle: The returned handle.
 616  *
 617  * This function returns a handle to an object that previously exported
 618  * a dma-buf. Note that we don't handle imports yet, because we simply
 619  * have no consumers of that implementation.
 620  */
 621 int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
 622                            int fd, u32 *handle)
 623 {
 624         struct ttm_object_device *tdev = tfile->tdev;
 625         struct dma_buf *dma_buf;
 626         struct ttm_prime_object *prime;
 627         struct ttm_base_object *base;
 628         int ret;
 629
 630         dma_buf = dma_buf_get(fd);
 631         if (IS_ERR(dma_buf))
 632                 return PTR_ERR(dma_buf);
 633
 634         if (dma_buf->ops != &tdev->ops)
 635                 return -ENOSYS;
 636
 637         prime = (struct ttm_prime_object *) dma_buf->priv;
 638         base = &prime->base;
 639         *handle = base->hash.key;
 640         ret = ttm_ref_object_add(tfile, base, TTM_REF_USAGE, NULL, false);
 641
 642         dma_buf_put(dma_buf);
 643
 644         return ret;
 645 }
 646 EXPORT_SYMBOL_GPL(ttm_prime_fd_to_handle);
 647
 648 /**
 649  * ttm_prime_handle_to_fd - Return a dma_buf fd from a ttm prime object
 650  *
 651  * @tfile: Struct ttm_object_file identifying the caller.
 652  * @handle: Handle to the object we're exporting from.
 653  * @flags: flags for dma-buf creation. We just pass them on.
 654  * @prime_fd: The returned file descriptor.
 655  *
 656  */
 657 int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
 658                            uint32_t handle, uint32_t flags,
 659                            int *prime_fd)
 660 {
 661         struct ttm_object_device *tdev = tfile->tdev;
 662         struct ttm_base_object *base;
 663         struct dma_buf *dma_buf;
 664         struct ttm_prime_object *prime;
 665         int ret;
 666
 667         base = ttm_base_object_lookup(tfile, handle);
 668         if (unlikely(base == NULL ||
 669                      base->object_type != ttm_prime_type)) {
 670                 ret = -ENOENT;
 671                 goto out_unref;
 672         }
 673
 674         prime = container_of(base, struct ttm_prime_object, base);
 675         if (unlikely(!base->shareable)) {
 676                 ret = -EPERM;
 677                 goto out_unref;
 678         }
 679
 680         ret = mutex_lock_interruptible(&prime->mutex);
 681         if (unlikely(ret != 0)) {
 682                 ret = -ERESTARTSYS;
 683                 goto out_unref;
 684         }
 685
 686         dma_buf = prime->dma_buf;
 687         if (!dma_buf || !get_dma_buf_unless_doomed(dma_buf)) {
 688                 DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 689
 690                 exp_info.ops = &tdev->ops;
 691                 exp_info.size = prime->size;
 692                 exp_info.flags = flags;
 693                 exp_info.priv = prime;
 694
 695                 /*
 696                  * Need to create a new dma_buf, with memory accounting.
 697                  */
 698                 ret = ttm_mem_global_alloc(tdev->mem_glob, tdev->dma_buf_size,
 699                                            false, true);
 700                 if (unlikely(ret != 0)) {
 701                         mutex_unlock(&prime->mutex);
 702                         goto out_unref;
 703                 }
 704
 705                 dma_buf = dma_buf_export(&exp_info);
 706                 if (IS_ERR(dma_buf)) {
 707                         ret = PTR_ERR(dma_buf);
 708                         ttm_mem_global_free(tdev->mem_glob,
 709                                             tdev->dma_buf_size);
 710                         mutex_unlock(&prime->mutex);
 711                         goto out_unref;
 712                 }
 713
 714                 /*
 715                  * dma_buf has taken the base object reference
 716                  */
 717                 base = NULL;
 718                 prime->dma_buf = dma_buf;
 719         }
 720         mutex_unlock(&prime->mutex);
 721
 722         ret = dma_buf_fd(dma_buf, flags);
 723         if (ret >= 0) {
 724                 *prime_fd = ret;
 725                 ret = 0;
 726         } else
 727                 dma_buf_put(dma_buf);
 728
 729 out_unref:
 730         if (base)
 731                 ttm_base_object_unref(&base);
 732         return ret;
 733 }
 734 EXPORT_SYMBOL_GPL(ttm_prime_handle_to_fd);
 735
 736 /**
 737  * ttm_prime_object_init - Initialize a ttm_prime_object
 738  *
 739  * @tfile: struct ttm_object_file identifying the caller
 740  * @size: The size of the dma_bufs we export.
 741  * @prime: The object to be initialized.
 742  * @shareable: See ttm_base_object_init
 743  * @type: See ttm_base_object_init
 744  * @refcount_release: See ttm_base_object_init
 745  * @ref_obj_release: See ttm_base_object_init
 746  *
 747  * Initializes an object which is compatible with the drm_prime model
 748  * for data sharing between processes and devices.
 749  */
 750 int ttm_prime_object_init(struct ttm_object_file *tfile, size_t size,
 751                           struct ttm_prime_object *prime, bool shareable,
 752                           enum ttm_object_type type,
 753                           void (*refcount_release) (struct ttm_base_object **),
 754                           void (*ref_obj_release) (struct ttm_base_object *,
 755                                                    enum ttm_ref_type ref_type))
 756 {
 757         mutex_init(&prime->mutex);
 758         prime->size = PAGE_ALIGN(size);
 759         prime->real_type = type;
 760         prime->dma_buf = NULL;
 761         prime->refcount_release = refcount_release;
 762         return ttm_base_object_init(tfile, &prime->base, shareable,
 763                                     ttm_prime_type,
 764                                     ttm_prime_refcount_release,
 765                                     ref_obj_release);
 766 }
 767 EXPORT_SYMBOL(ttm_prime_object_init);