drivers/gpu/drm/drm_prime.c

   1 /*
   2  * Copyright © 2012 Red Hat
   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  *      Dave Airlie <airlied@redhat.com>
  25  *      Rob Clark <rob.clark@linaro.org>
  26  *
  27  */
  28
  29 #include <linux/export.h>
  30 #include <linux/dma-buf.h>
  31 #include <drm/drmP.h>
  32
  33 /*
  34  * DMA-BUF/GEM Object references and lifetime overview:
  35  *
  36  * On the export the dma_buf holds a reference to the exporting GEM
  37  * object. It takes this reference in handle_to_fd_ioctl, when it
  38  * first calls .prime_export and stores the exporting GEM object in
  39  * the dma_buf priv. This reference is released when the dma_buf
  40  * object goes away in the driver .release function.
  41  *
  42  * On the import the importing GEM object holds a reference to the
  43  * dma_buf (which in turn holds a ref to the exporting GEM object).
  44  * It takes that reference in the fd_to_handle ioctl.
  45  * It calls dma_buf_get, creates an attachment to it and stores the
  46  * attachment in the GEM object. When this attachment is destroyed
  47  * when the imported object is destroyed, we remove the attachment
  48  * and drop the reference to the dma_buf.
  49  *
  50  * Thus the chain of references always flows in one direction
  51  * (avoiding loops): importing_gem -> dmabuf -> exporting_gem
  52  *
  53  * Self-importing: if userspace is using PRIME as a replacement for flink
  54  * then it will get a fd->handle request for a GEM object that it created.
  55  * Drivers should detect this situation and return back the gem object
  56  * from the dma-buf private.  Prime will do this automatically for drivers that
  57  * use the drm_gem_prime_{import,export} helpers.
  58  */
  59
  60 struct drm_prime_member {
  61         struct list_head entry;
  62         struct dma_buf *dma_buf;
  63         uint32_t handle;
  64 };
  65
  66 struct drm_prime_attachment {
  67         struct sg_table *sgt;
  68         enum dma_data_direction dir;
  69 };
  70
  71 static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle)
  72 {
  73         struct drm_prime_member *member;
  74
  75         member = kmalloc(sizeof(*member), GFP_KERNEL);
  76         if (!member)
  77                 return -ENOMEM;
  78
  79         get_dma_buf(dma_buf);
  80         member->dma_buf = dma_buf;
  81         member->handle = handle;
  82         list_add(&member->entry, &prime_fpriv->head);
  83         return 0;
  84 }
  85
  86 static int drm_gem_map_attach(struct dma_buf *dma_buf,
  87                               struct device *target_dev,
  88                               struct dma_buf_attachment *attach)
  89 {
  90         struct drm_prime_attachment *prime_attach;
  91         struct drm_gem_object *obj = dma_buf->priv;
  92         struct drm_device *dev = obj->dev;
  93
  94         prime_attach = kzalloc(sizeof(*prime_attach), GFP_KERNEL);
  95         if (!prime_attach)
  96                 return -ENOMEM;
  97
  98         prime_attach->dir = DMA_NONE;
  99         attach->priv = prime_attach;
 100
 101         if (!dev->driver->gem_prime_pin)
 102                 return 0;
 103
 104         return dev->driver->gem_prime_pin(obj);
 105 }
 106
 107 static void drm_gem_map_detach(struct dma_buf *dma_buf,
 108                                struct dma_buf_attachment *attach)
 109 {
 110         struct drm_prime_attachment *prime_attach = attach->priv;
 111         struct drm_gem_object *obj = dma_buf->priv;
 112         struct drm_device *dev = obj->dev;
 113         struct sg_table *sgt;
 114
 115         if (dev->driver->gem_prime_unpin)
 116                 dev->driver->gem_prime_unpin(obj);
 117
 118         if (!prime_attach)
 119                 return;
 120
 121         sgt = prime_attach->sgt;
 122         if (sgt) {
 123                 if (prime_attach->dir != DMA_NONE)
 124                         dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents,
 125                                         prime_attach->dir);
 126                 sg_free_table(sgt);
 127         }
 128
 129         kfree(sgt);
 130         kfree(prime_attach);
 131         attach->priv = NULL;
 132 }
 133
 134 static void drm_prime_remove_buf_handle_locked(
 135                 struct drm_prime_file_private *prime_fpriv,
 136                 struct dma_buf *dma_buf)
 137 {
 138         struct drm_prime_member *member, *safe;
 139
 140         list_for_each_entry_safe(member, safe, &prime_fpriv->head, entry) {
 141                 if (member->dma_buf == dma_buf) {
 142                         dma_buf_put(dma_buf);
 143                         list_del(&member->entry);
 144                         kfree(member);
 145                 }
 146         }
 147 }
 148
 149 static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
 150                 enum dma_data_direction dir)
 151 {
 152         struct drm_prime_attachment *prime_attach = attach->priv;
 153         struct drm_gem_object *obj = attach->dmabuf->priv;
 154         struct sg_table *sgt;
 155
 156         if (WARN_ON(dir == DMA_NONE || !prime_attach))
 157                 return ERR_PTR(-EINVAL);
 158
 159         /* return the cached mapping when possible */
 160         if (prime_attach->dir == dir)
 161                 return prime_attach->sgt;
 162
 163         /*
 164          * two mappings with different directions for the same attachment are
 165          * not allowed
 166          */
 167         if (WARN_ON(prime_attach->dir != DMA_NONE))
 168                 return ERR_PTR(-EBUSY);
 169
 170         sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
 171
 172         if (!IS_ERR(sgt)) {
 173                 if (!dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir)) {
 174                         sg_free_table(sgt);
 175                         kfree(sgt);
 176                         sgt = ERR_PTR(-ENOMEM);
 177                 } else {
 178                         prime_attach->sgt = sgt;
 179                         prime_attach->dir = dir;
 180                 }
 181         }
 182
 183         return sgt;
 184 }
 185
 186 static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
 187                 struct sg_table *sgt, enum dma_data_direction dir)
 188 {
 189         /* nothing to be done here */
 190 }
 191
 192 void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
 193 {
 194         struct drm_gem_object *obj = dma_buf->priv;
 195
 196         /* drop the reference on the export fd holds */
 197         drm_gem_object_unreference_unlocked(obj);
 198 }
 199 EXPORT_SYMBOL(drm_gem_dmabuf_release);
 200
 201 static void *drm_gem_dmabuf_vmap(struct dma_buf *dma_buf)
 202 {
 203         struct drm_gem_object *obj = dma_buf->priv;
 204         struct drm_device *dev = obj->dev;
 205
 206         return dev->driver->gem_prime_vmap(obj);
 207 }
 208
 209 static void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
 210 {
 211         struct drm_gem_object *obj = dma_buf->priv;
 212         struct drm_device *dev = obj->dev;
 213
 214         dev->driver->gem_prime_vunmap(obj, vaddr);
 215 }
 216
 217 static void *drm_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf,
 218                 unsigned long page_num)
 219 {
 220         return NULL;
 221 }
 222
 223 static void drm_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
 224                 unsigned long page_num, void *addr)
 225 {
 226
 227 }
 228 static void *drm_gem_dmabuf_kmap(struct dma_buf *dma_buf,
 229                 unsigned long page_num)
 230 {
 231         return NULL;
 232 }
 233
 234 static void drm_gem_dmabuf_kunmap(struct dma_buf *dma_buf,
 235                 unsigned long page_num, void *addr)
 236 {
 237
 238 }
 239
 240 static int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf,
 241                 struct vm_area_struct *vma)
 242 {
 243         struct drm_gem_object *obj = dma_buf->priv;
 244         struct drm_device *dev = obj->dev;
 245
 246         if (!dev->driver->gem_prime_mmap)
 247                 return -ENOSYS;
 248
 249         return dev->driver->gem_prime_mmap(obj, vma);
 250 }
 251
 252 static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
 253         .attach = drm_gem_map_attach,
 254         .detach = drm_gem_map_detach,
 255         .map_dma_buf = drm_gem_map_dma_buf,
 256         .unmap_dma_buf = drm_gem_unmap_dma_buf,
 257         .release = drm_gem_dmabuf_release,
 258         .kmap = drm_gem_dmabuf_kmap,
 259         .kmap_atomic = drm_gem_dmabuf_kmap_atomic,
 260         .kunmap = drm_gem_dmabuf_kunmap,
 261         .kunmap_atomic = drm_gem_dmabuf_kunmap_atomic,
 262         .mmap = drm_gem_dmabuf_mmap,
 263         .vmap = drm_gem_dmabuf_vmap,
 264         .vunmap = drm_gem_dmabuf_vunmap,
 265 };
 266
 267 /**
 268  * DOC: PRIME Helpers
 269  *
 270  * Drivers can implement @gem_prime_export and @gem_prime_import in terms of
 271  * simpler APIs by using the helper functions @drm_gem_prime_export and
 272  * @drm_gem_prime_import.  These functions implement dma-buf support in terms of
 273  * five lower-level driver callbacks:
 274  *
 275  * Export callbacks:
 276  *
 277  *  - @gem_prime_pin (optional): prepare a GEM object for exporting
 278  *
 279  *  - @gem_prime_get_sg_table: provide a scatter/gather table of pinned pages
 280  *
 281  *  - @gem_prime_vmap: vmap a buffer exported by your driver
 282  *
 283  *  - @gem_prime_vunmap: vunmap a buffer exported by your driver
 284  *
 285  * Import callback:
 286  *
 287  *  - @gem_prime_import_sg_table (import): produce a GEM object from another
 288  *    driver's scatter/gather table
 289  */
 290
 291 struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
 292                                      struct drm_gem_object *obj, int flags)
 293 {
 294         return dma_buf_export(obj, &drm_gem_prime_dmabuf_ops, obj->size, flags);
 295 }
 296 EXPORT_SYMBOL(drm_gem_prime_export);
 297
 298 static struct dma_buf *export_and_register_object(struct drm_device *dev,
 299                                                   struct drm_gem_object *obj,
 300                                                   uint32_t flags)
 301 {
 302         struct dma_buf *dmabuf;
 303
 304         /* prevent races with concurrent gem_close. */
 305         if (obj->handle_count == 0) {
 306                 dmabuf = ERR_PTR(-ENOENT);
 307                 return dmabuf;
 308         }
 309
 310         dmabuf = dev->driver->gem_prime_export(dev, obj, flags);
 311         if (IS_ERR(dmabuf)) {
 312                 /* normally the created dma-buf takes ownership of the ref,
 313                  * but if that fails then drop the ref
 314                  */
 315                 return dmabuf;
 316         }
 317
 318         /*
 319          * Note that callers do not need to clean up the export cache
 320          * since the check for obj->handle_count guarantees that someone
 321          * will clean it up.
 322          */
 323         obj->dma_buf = dmabuf;
 324         get_dma_buf(obj->dma_buf);
 325
 326         return dmabuf;
 327 }
 328
 329 int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 330                 struct drm_file *file_priv, uint32_t handle, uint32_t flags,
 331                 int *prime_fd)
 332 {
 333         struct drm_gem_object *obj;
 334         int ret = 0;
 335         struct dma_buf *dmabuf;
 336
 337         obj = drm_gem_object_lookup(dev, file_priv, handle);
 338         if (!obj)
 339                 return -ENOENT;
 340
 341         /* re-export the original imported object */
 342         if (obj->import_attach) {
 343                 dmabuf = obj->import_attach->dmabuf;
 344                 get_dma_buf(dmabuf);
 345                 goto out_have_obj;
 346         }
 347
 348         mutex_lock(&dev->object_name_lock);
 349         if (obj->dma_buf) {
 350                 get_dma_buf(obj->dma_buf);
 351                 dmabuf = obj->dma_buf;
 352                 mutex_unlock(&dev->object_name_lock);
 353                 goto out_have_obj;
 354         }
 355
 356         dmabuf = export_and_register_object(dev, obj, flags);
 357         mutex_unlock(&dev->object_name_lock);
 358         if (IS_ERR(dmabuf)) {
 359                 /* normally the created dma-buf takes ownership of the ref,
 360                  * but if that fails then drop the ref
 361                  */
 362                 ret = PTR_ERR(dmabuf);
 363                 goto out;
 364         }
 365
 366         mutex_lock(&file_priv->prime.lock);
 367         /* if we've exported this buffer the cheat and add it to the import list
 368          * so we get the correct handle back
 369          */
 370         ret = drm_prime_add_buf_handle(&file_priv->prime,
 371                                        dmabuf, handle);
 372         if (ret)
 373                 goto fail_put_dmabuf;
 374
 375         ret = dma_buf_fd(dmabuf, flags);
 376         if (ret < 0)
 377                 goto fail_rm_handle;
 378
 379         *prime_fd = ret;
 380         mutex_unlock(&file_priv->prime.lock);
 381         return 0;
 382
 383 out_have_obj:
 384         ret = dma_buf_fd(dmabuf, flags);
 385         if (ret < 0) {
 386                 dma_buf_put(dmabuf);
 387         } else {
 388                 *prime_fd = ret;
 389                 ret = 0;
 390         }
 391
 392         goto out;
 393
 394 fail_rm_handle:
 395         drm_prime_remove_buf_handle_locked(&file_priv->prime,
 396                                            dmabuf);
 397         mutex_unlock(&file_priv->prime.lock);
 398 fail_put_dmabuf:
 399         dma_buf_put(dmabuf);
 400 out:
 401         drm_gem_object_unreference_unlocked(obj);
 402         return ret;
 403 }
 404 EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
 405
 406 struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 407                                             struct dma_buf *dma_buf)
 408 {
 409         struct dma_buf_attachment *attach;
 410         struct sg_table *sgt;
 411         struct drm_gem_object *obj;
 412         int ret;
 413
 414         if (!dev->driver->gem_prime_import_sg_table)
 415                 return ERR_PTR(-EINVAL);
 416
 417         if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
 418                 obj = dma_buf->priv;
 419                 if (obj->dev == dev) {
 420                         /*
 421                          * Importing dmabuf exported from out own gem increases
 422                          * refcount on gem itself instead of f_count of dmabuf.
 423                          */
 424                         drm_gem_object_reference(obj);
 425                         return obj;
 426                 }
 427         }
 428
 429         attach = dma_buf_attach(dma_buf, dev->dev);
 430         if (IS_ERR(attach))
 431                 return ERR_CAST(attach);
 432
 433         get_dma_buf(dma_buf);
 434
 435         sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
 436         if (IS_ERR_OR_NULL(sgt)) {
 437                 ret = PTR_ERR(sgt);
 438                 goto fail_detach;
 439         }
 440
 441         obj = dev->driver->gem_prime_import_sg_table(dev, dma_buf->size, sgt);
 442         if (IS_ERR(obj)) {
 443                 ret = PTR_ERR(obj);
 444                 goto fail_unmap;
 445         }
 446
 447         obj->import_attach = attach;
 448
 449         return obj;
 450
 451 fail_unmap:
 452         dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
 453 fail_detach:
 454         dma_buf_detach(dma_buf, attach);
 455         dma_buf_put(dma_buf);
 456
 457         return ERR_PTR(ret);
 458 }
 459 EXPORT_SYMBOL(drm_gem_prime_import);
 460
 461 int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 462                 struct drm_file *file_priv, int prime_fd, uint32_t *handle)
 463 {
 464         struct dma_buf *dma_buf;
 465         struct drm_gem_object *obj;
 466         int ret;
 467
 468         dma_buf = dma_buf_get(prime_fd);
 469         if (IS_ERR(dma_buf))
 470                 return PTR_ERR(dma_buf);
 471
 472         mutex_lock(&file_priv->prime.lock);
 473
 474         ret = drm_prime_lookup_buf_handle(&file_priv->prime,
 475                         dma_buf, handle);
 476         if (ret == 0)
 477                 goto out_put;
 478
 479         /* never seen this one, need to import */
 480         mutex_lock(&dev->object_name_lock);
 481         obj = dev->driver->gem_prime_import(dev, dma_buf);
 482         if (IS_ERR(obj)) {
 483                 ret = PTR_ERR(obj);
 484                 goto out_unlock;
 485         }
 486
 487         if (obj->dma_buf) {
 488                 WARN_ON(obj->dma_buf != dma_buf);
 489         } else {
 490                 obj->dma_buf = dma_buf;
 491                 get_dma_buf(dma_buf);
 492         }
 493
 494         /* drm_gem_handle_create_tail unlocks dev->object_name_lock. */
 495         ret = drm_gem_handle_create_tail(file_priv, obj, handle);
 496         drm_gem_object_unreference_unlocked(obj);
 497         if (ret)
 498                 goto out_put;
 499
 500         ret = drm_prime_add_buf_handle(&file_priv->prime,
 501                         dma_buf, *handle);
 502         if (ret)
 503                 goto fail;
 504
 505         mutex_unlock(&file_priv->prime.lock);
 506
 507         dma_buf_put(dma_buf);
 508
 509         return 0;
 510
 511 fail:
 512         /* hmm, if driver attached, we are relying on the free-object path
 513          * to detach.. which seems ok..
 514          */
 515         drm_gem_handle_delete(file_priv, *handle);
 516 out_unlock:
 517         mutex_lock(&dev->object_name_lock);
 518 out_put:
 519         dma_buf_put(dma_buf);
 520         mutex_unlock(&file_priv->prime.lock);
 521         return ret;
 522 }
 523 EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
 524
 525 int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
 526                                  struct drm_file *file_priv)
 527 {
 528         struct drm_prime_handle *args = data;
 529         uint32_t flags;
 530
 531         if (!drm_core_check_feature(dev, DRIVER_PRIME))
 532                 return -EINVAL;
 533
 534         if (!dev->driver->prime_handle_to_fd)
 535                 return -ENOSYS;
 536
 537         /* check flags are valid */
 538         if (args->flags & ~DRM_CLOEXEC)
 539                 return -EINVAL;
 540
 541         /* we only want to pass DRM_CLOEXEC which is == O_CLOEXEC */
 542         flags = args->flags & DRM_CLOEXEC;
 543
 544         return dev->driver->prime_handle_to_fd(dev, file_priv,
 545                         args->handle, flags, &args->fd);
 546 }
 547
 548 int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
 549                                  struct drm_file *file_priv)
 550 {
 551         struct drm_prime_handle *args = data;
 552
 553         if (!drm_core_check_feature(dev, DRIVER_PRIME))
 554                 return -EINVAL;
 555
 556         if (!dev->driver->prime_fd_to_handle)
 557                 return -ENOSYS;
 558
 559         return dev->driver->prime_fd_to_handle(dev, file_priv,
 560                         args->fd, &args->handle);
 561 }
 562
 563 /*
 564  * drm_prime_pages_to_sg
 565  *
 566  * this helper creates an sg table object from a set of pages
 567  * the driver is responsible for mapping the pages into the
 568  * importers address space
 569  */
 570 struct sg_table *drm_prime_pages_to_sg(struct page **pages, int nr_pages)
 571 {
 572         struct sg_table *sg = NULL;
 573         int ret;
 574
 575         sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
 576         if (!sg) {
 577                 ret = -ENOMEM;
 578                 goto out;
 579         }
 580
 581         ret = sg_alloc_table_from_pages(sg, pages, nr_pages, 0,
 582                                 nr_pages << PAGE_SHIFT, GFP_KERNEL);
 583         if (ret)
 584                 goto out;
 585
 586         return sg;
 587 out:
 588         kfree(sg);
 589         return ERR_PTR(ret);
 590 }
 591 EXPORT_SYMBOL(drm_prime_pages_to_sg);
 592
 593 /* export an sg table into an array of pages and addresses
 594    this is currently required by the TTM driver in order to do correct fault
 595    handling */
 596 int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
 597                                      dma_addr_t *addrs, int max_pages)
 598 {
 599         unsigned count;
 600         struct scatterlist *sg;
 601         struct page *page;
 602         u32 len, offset;
 603         int pg_index;
 604         dma_addr_t addr;
 605
 606         pg_index = 0;
 607         for_each_sg(sgt->sgl, sg, sgt->nents, count) {
 608                 len = sg->length;
 609                 offset = sg->offset;
 610                 page = sg_page(sg);
 611                 addr = sg_dma_address(sg);
 612
 613                 while (len > 0) {
 614                         if (WARN_ON(pg_index >= max_pages))
 615                                 return -1;
 616                         pages[pg_index] = page;
 617                         if (addrs)
 618                                 addrs[pg_index] = addr;
 619
 620                         page++;
 621                         addr += PAGE_SIZE;
 622                         len -= PAGE_SIZE;
 623                         pg_index++;
 624                 }
 625         }
 626         return 0;
 627 }
 628 EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
 629 /* helper function to cleanup a GEM/prime object */
 630 void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
 631 {
 632         struct dma_buf_attachment *attach;
 633         struct dma_buf *dma_buf;
 634         attach = obj->import_attach;
 635         if (sg)
 636                 dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
 637         dma_buf = attach->dmabuf;
 638         dma_buf_detach(attach->dmabuf, attach);
 639         /* remove the reference */
 640         dma_buf_put(dma_buf);
 641 }
 642 EXPORT_SYMBOL(drm_prime_gem_destroy);
 643
 644 void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
 645 {
 646         INIT_LIST_HEAD(&prime_fpriv->head);
 647         mutex_init(&prime_fpriv->lock);
 648 }
 649 EXPORT_SYMBOL(drm_prime_init_file_private);
 650
 651 void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
 652 {
 653         /* by now drm_gem_release should've made sure the list is empty */
 654         WARN_ON(!list_empty(&prime_fpriv->head));
 655 }
 656 EXPORT_SYMBOL(drm_prime_destroy_file_private);
 657
 658 int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle)
 659 {
 660         struct drm_prime_member *member;
 661
 662         list_for_each_entry(member, &prime_fpriv->head, entry) {
 663                 if (member->dma_buf == dma_buf) {
 664                         *handle = member->handle;
 665                         return 0;
 666                 }
 667         }
 668         return -ENOENT;
 669 }
 670 EXPORT_SYMBOL(drm_prime_lookup_buf_handle);
 671
 672 void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf)
 673 {
 674         mutex_lock(&prime_fpriv->lock);
 675         drm_prime_remove_buf_handle_locked(prime_fpriv, dma_buf);
 676         mutex_unlock(&prime_fpriv->lock);
 677 }
 678 EXPORT_SYMBOL(drm_prime_remove_buf_handle);