drivers/dma-buf/dma-resv.c

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * Copyright (C) 2012-2014 Canonical Ltd (Maarten Lankhorst)
   4  *
   5  * Based on bo.c which bears the following copyright notice,
   6  * but is dual licensed:
   7  *
   8  * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
   9  * All Rights Reserved.
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a
  12  * copy of this software and associated documentation files (the
  13  * "Software"), to deal in the Software without restriction, including
  14  * without limitation the rights to use, copy, modify, merge, publish,
  15  * distribute, sub license, and/or sell copies of the Software, and to
  16  * permit persons to whom the Software is furnished to do so, subject to
  17  * the following conditions:
  18  *
  19  * The above copyright notice and this permission notice (including the
  20  * next paragraph) shall be included in all copies or substantial portions
  21  * of the Software.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  24  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  25  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  26  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  27  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  28  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  29  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  30  *
  31  **************************************************************************/
  32 /*
  33  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  34  */
  35
  36 #include <linux/dma-resv.h>
  37 #include <linux/export.h>
  38 #include <linux/mm.h>
  39 #include <linux/sched/mm.h>
  40 #include <linux/mmu_notifier.h>
  41 #include <linux/seq_file.h>
  42
  43 /**
  44  * DOC: Reservation Object Overview
  45  *
  46  * The reservation object provides a mechanism to manage shared and
  47  * exclusive fences associated with a buffer.  A reservation object
  48  * can have attached one exclusive fence (normally associated with
  49  * write operations) or N shared fences (read operations).  The RCU
  50  * mechanism is used to protect read access to fences from locked
  51  * write-side updates.
  52  *
  53  * See struct dma_resv for more details.
  54  */
  55
  56 DEFINE_WD_CLASS(reservation_ww_class);
  57 EXPORT_SYMBOL(reservation_ww_class);
  58
  59 /**
  60  * dma_resv_list_alloc - allocate fence list
  61  * @shared_max: number of fences we need space for
  62  *
  63  * Allocate a new dma_resv_list and make sure to correctly initialize
  64  * shared_max.
  65  */
  66 static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
  67 {
  68         struct dma_resv_list *list;
  69
  70         list = kmalloc(struct_size(list, shared, shared_max), GFP_KERNEL);
  71         if (!list)
  72                 return NULL;
  73
  74         list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
  75                 sizeof(*list->shared);
  76
  77         return list;
  78 }
  79
  80 /**
  81  * dma_resv_list_free - free fence list
  82  * @list: list to free
  83  *
  84  * Free a dma_resv_list and make sure to drop all references.
  85  */
  86 static void dma_resv_list_free(struct dma_resv_list *list)
  87 {
  88         unsigned int i;
  89
  90         if (!list)
  91                 return;
  92
  93         for (i = 0; i < list->shared_count; ++i)
  94                 dma_fence_put(rcu_dereference_protected(list->shared[i], true));
  95
  96         kfree_rcu(list, rcu);
  97 }
  98
  99 /**
 100  * dma_resv_init - initialize a reservation object
 101  * @obj: the reservation object
 102  */
 103 void dma_resv_init(struct dma_resv *obj)
 104 {
 105         ww_mutex_init(&obj->lock, &reservation_ww_class);
 106         seqcount_ww_mutex_init(&obj->seq, &obj->lock);
 107
 108         RCU_INIT_POINTER(obj->fence, NULL);
 109         RCU_INIT_POINTER(obj->fence_excl, NULL);
 110 }
 111 EXPORT_SYMBOL(dma_resv_init);
 112
 113 /**
 114  * dma_resv_fini - destroys a reservation object
 115  * @obj: the reservation object
 116  */
 117 void dma_resv_fini(struct dma_resv *obj)
 118 {
 119         struct dma_resv_list *fobj;
 120         struct dma_fence *excl;
 121
 122         /*
 123          * This object should be dead and all references must have
 124          * been released to it, so no need to be protected with rcu.
 125          */
 126         excl = rcu_dereference_protected(obj->fence_excl, 1);
 127         if (excl)
 128                 dma_fence_put(excl);
 129
 130         fobj = rcu_dereference_protected(obj->fence, 1);
 131         dma_resv_list_free(fobj);
 132         ww_mutex_destroy(&obj->lock);
 133 }
 134 EXPORT_SYMBOL(dma_resv_fini);
 135
 136 /**
 137  * dma_resv_reserve_shared - Reserve space to add shared fences to
 138  * a dma_resv.
 139  * @obj: reservation object
 140  * @num_fences: number of fences we want to add
 141  *
 142  * Should be called before dma_resv_add_shared_fence().  Must
 143  * be called with @obj locked through dma_resv_lock().
 144  *
 145  * Note that the preallocated slots need to be re-reserved if @obj is unlocked
 146  * at any time before calling dma_resv_add_shared_fence(). This is validated
 147  * when CONFIG_DEBUG_MUTEXES is enabled.
 148  *
 149  * RETURNS
 150  * Zero for success, or -errno
 151  */
 152 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
 153 {
 154         struct dma_resv_list *old, *new;
 155         unsigned int i, j, k, max;
 156
 157         dma_resv_assert_held(obj);
 158
 159         old = dma_resv_shared_list(obj);
 160         if (old && old->shared_max) {
 161                 if ((old->shared_count + num_fences) <= old->shared_max)
 162                         return 0;
 163                 max = max(old->shared_count + num_fences, old->shared_max * 2);
 164         } else {
 165                 max = max(4ul, roundup_pow_of_two(num_fences));
 166         }
 167
 168         new = dma_resv_list_alloc(max);
 169         if (!new)
 170                 return -ENOMEM;
 171
 172         /*
 173          * no need to bump fence refcounts, rcu_read access
 174          * requires the use of kref_get_unless_zero, and the
 175          * references from the old struct are carried over to
 176          * the new.
 177          */
 178         for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
 179                 struct dma_fence *fence;
 180
 181                 fence = rcu_dereference_protected(old->shared[i],
 182                                                   dma_resv_held(obj));
 183                 if (dma_fence_is_signaled(fence))
 184                         RCU_INIT_POINTER(new->shared[--k], fence);
 185                 else
 186                         RCU_INIT_POINTER(new->shared[j++], fence);
 187         }
 188         new->shared_count = j;
 189
 190         /*
 191          * We are not changing the effective set of fences here so can
 192          * merely update the pointer to the new array; both existing
 193          * readers and new readers will see exactly the same set of
 194          * active (unsignaled) shared fences. Individual fences and the
 195          * old array are protected by RCU and so will not vanish under
 196          * the gaze of the rcu_read_lock() readers.
 197          */
 198         rcu_assign_pointer(obj->fence, new);
 199
 200         if (!old)
 201                 return 0;
 202
 203         /* Drop the references to the signaled fences */
 204         for (i = k; i < max; ++i) {
 205                 struct dma_fence *fence;
 206
 207                 fence = rcu_dereference_protected(new->shared[i],
 208                                                   dma_resv_held(obj));
 209                 dma_fence_put(fence);
 210         }
 211         kfree_rcu(old, rcu);
 212
 213         return 0;
 214 }
 215 EXPORT_SYMBOL(dma_resv_reserve_shared);
 216
 217 #ifdef CONFIG_DEBUG_MUTEXES
 218 /**
 219  * dma_resv_reset_shared_max - reset shared fences for debugging
 220  * @obj: the dma_resv object to reset
 221  *
 222  * Reset the number of pre-reserved shared slots to test that drivers do
 223  * correct slot allocation using dma_resv_reserve_shared(). See also
 224  * &dma_resv_list.shared_max.
 225  */
 226 void dma_resv_reset_shared_max(struct dma_resv *obj)
 227 {
 228         struct dma_resv_list *fences = dma_resv_shared_list(obj);
 229
 230         dma_resv_assert_held(obj);
 231
 232         /* Test shared fence slot reservation */
 233         if (fences)
 234                 fences->shared_max = fences->shared_count;
 235 }
 236 EXPORT_SYMBOL(dma_resv_reset_shared_max);
 237 #endif
 238
 239 /**
 240  * dma_resv_add_shared_fence - Add a fence to a shared slot
 241  * @obj: the reservation object
 242  * @fence: the shared fence to add
 243  *
 244  * Add a fence to a shared slot, @obj must be locked with dma_resv_lock(), and
 245  * dma_resv_reserve_shared() has been called.
 246  *
 247  * See also &dma_resv.fence for a discussion of the semantics.
 248  */
 249 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
 250 {
 251         struct dma_resv_list *fobj;
 252         struct dma_fence *old;
 253         unsigned int i, count;
 254
 255         dma_fence_get(fence);
 256
 257         dma_resv_assert_held(obj);
 258
 259         fobj = dma_resv_shared_list(obj);
 260         count = fobj->shared_count;
 261
 262         write_seqcount_begin(&obj->seq);
 263
 264         for (i = 0; i < count; ++i) {
 265
 266                 old = rcu_dereference_protected(fobj->shared[i],
 267                                                 dma_resv_held(obj));
 268                 if (old->context == fence->context ||
 269                     dma_fence_is_signaled(old))
 270                         goto replace;
 271         }
 272
 273         BUG_ON(fobj->shared_count >= fobj->shared_max);
 274         old = NULL;
 275         count++;
 276
 277 replace:
 278         RCU_INIT_POINTER(fobj->shared[i], fence);
 279         /* pointer update must be visible before we extend the shared_count */
 280         smp_store_mb(fobj->shared_count, count);
 281
 282         write_seqcount_end(&obj->seq);
 283         dma_fence_put(old);
 284 }
 285 EXPORT_SYMBOL(dma_resv_add_shared_fence);
 286
 287 /**
 288  * dma_resv_add_excl_fence - Add an exclusive fence.
 289  * @obj: the reservation object
 290  * @fence: the exclusive fence to add
 291  *
 292  * Add a fence to the exclusive slot. @obj must be locked with dma_resv_lock().
 293  * Note that this function replaces all fences attached to @obj, see also
 294  * &dma_resv.fence_excl for a discussion of the semantics.
 295  */
 296 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 297 {
 298         struct dma_fence *old_fence = dma_resv_excl_fence(obj);
 299         struct dma_resv_list *old;
 300         u32 i = 0;
 301
 302         dma_resv_assert_held(obj);
 303
 304         old = dma_resv_shared_list(obj);
 305         if (old)
 306                 i = old->shared_count;
 307
 308         if (fence)
 309                 dma_fence_get(fence);
 310
 311         write_seqcount_begin(&obj->seq);
 312         /* write_seqcount_begin provides the necessary memory barrier */
 313         RCU_INIT_POINTER(obj->fence_excl, fence);
 314         if (old)
 315                 old->shared_count = 0;
 316         write_seqcount_end(&obj->seq);
 317
 318         /* inplace update, no shared fences */
 319         while (i--)
 320                 dma_fence_put(rcu_dereference_protected(old->shared[i],
 321                                                 dma_resv_held(obj)));
 322
 323         dma_fence_put(old_fence);
 324 }
 325 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 326
 327 /**
 328  * dma_resv_iter_restart_unlocked - restart the unlocked iterator
 329  * @cursor: The dma_resv_iter object to restart
 330  *
 331  * Restart the unlocked iteration by initializing the cursor object.
 332  */
 333 static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
 334 {
 335         cursor->seq = read_seqcount_begin(&cursor->obj->seq);
 336         cursor->index = -1;
 337         cursor->shared_count = 0;
 338         if (cursor->all_fences) {
 339                 cursor->fences = dma_resv_shared_list(cursor->obj);
 340                 if (cursor->fences)
 341                         cursor->shared_count = cursor->fences->shared_count;
 342         } else {
 343                 cursor->fences = NULL;
 344         }
 345         cursor->is_restarted = true;
 346 }
 347
 348 /**
 349  * dma_resv_iter_walk_unlocked - walk over fences in a dma_resv obj
 350  * @cursor: cursor to record the current position
 351  *
 352  * Return all the fences in the dma_resv object which are not yet signaled.
 353  * The returned fence has an extra local reference so will stay alive.
 354  * If a concurrent modify is detected the whole iteration is started over again.
 355  */
 356 static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
 357 {
 358         struct dma_resv *obj = cursor->obj;
 359
 360         do {
 361                 /* Drop the reference from the previous round */
 362                 dma_fence_put(cursor->fence);
 363
 364                 if (cursor->index == -1) {
 365                         cursor->fence = dma_resv_excl_fence(obj);
 366                         cursor->index++;
 367                         if (!cursor->fence)
 368                                 continue;
 369
 370                 } else if (!cursor->fences ||
 371                            cursor->index >= cursor->shared_count) {
 372                         cursor->fence = NULL;
 373                         break;
 374
 375                 } else {
 376                         struct dma_resv_list *fences = cursor->fences;
 377                         unsigned int idx = cursor->index++;
 378
 379                         cursor->fence = rcu_dereference(fences->shared[idx]);
 380                 }
 381                 cursor->fence = dma_fence_get_rcu(cursor->fence);
 382                 if (!cursor->fence || !dma_fence_is_signaled(cursor->fence))
 383                         break;
 384         } while (true);
 385 }
 386
 387 /**
 388  * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
 389  * @cursor: the cursor with the current position
 390  *
 391  * Returns the first fence from an unlocked dma_resv obj.
 392  */
 393 struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
 394 {
 395         rcu_read_lock();
 396         do {
 397                 dma_resv_iter_restart_unlocked(cursor);
 398                 dma_resv_iter_walk_unlocked(cursor);
 399         } while (read_seqcount_retry(&cursor->obj->seq, cursor->seq));
 400         rcu_read_unlock();
 401
 402         return cursor->fence;
 403 }
 404 EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
 405
 406 /**
 407  * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
 408  * @cursor: the cursor with the current position
 409  *
 410  * Returns the next fence from an unlocked dma_resv obj.
 411  */
 412 struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
 413 {
 414         bool restart;
 415
 416         rcu_read_lock();
 417         cursor->is_restarted = false;
 418         restart = read_seqcount_retry(&cursor->obj->seq, cursor->seq);
 419         do {
 420                 if (restart)
 421                         dma_resv_iter_restart_unlocked(cursor);
 422                 dma_resv_iter_walk_unlocked(cursor);
 423                 restart = true;
 424         } while (read_seqcount_retry(&cursor->obj->seq, cursor->seq));
 425         rcu_read_unlock();
 426
 427         return cursor->fence;
 428 }
 429 EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
 430
 431 /**
 432  * dma_resv_iter_first - first fence from a locked dma_resv object
 433  * @cursor: cursor to record the current position
 434  *
 435  * Return the first fence in the dma_resv object while holding the
 436  * &dma_resv.lock.
 437  */
 438 struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
 439 {
 440         struct dma_fence *fence;
 441
 442         dma_resv_assert_held(cursor->obj);
 443
 444         cursor->index = 0;
 445         if (cursor->all_fences)
 446                 cursor->fences = dma_resv_shared_list(cursor->obj);
 447         else
 448                 cursor->fences = NULL;
 449
 450         fence = dma_resv_excl_fence(cursor->obj);
 451         if (!fence)
 452                 fence = dma_resv_iter_next(cursor);
 453
 454         cursor->is_restarted = true;
 455         return fence;
 456 }
 457 EXPORT_SYMBOL_GPL(dma_resv_iter_first);
 458
 459 /**
 460  * dma_resv_iter_next - next fence from a locked dma_resv object
 461  * @cursor: cursor to record the current position
 462  *
 463  * Return the next fences from the dma_resv object while holding the
 464  * &dma_resv.lock.
 465  */
 466 struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
 467 {
 468         unsigned int idx;
 469
 470         dma_resv_assert_held(cursor->obj);
 471
 472         cursor->is_restarted = false;
 473         if (!cursor->fences || cursor->index >= cursor->fences->shared_count)
 474                 return NULL;
 475
 476         idx = cursor->index++;
 477         return rcu_dereference_protected(cursor->fences->shared[idx],
 478                                          dma_resv_held(cursor->obj));
 479 }
 480 EXPORT_SYMBOL_GPL(dma_resv_iter_next);
 481
 482 /**
 483  * dma_resv_copy_fences - Copy all fences from src to dst.
 484  * @dst: the destination reservation object
 485  * @src: the source reservation object
 486  *
 487  * Copy all fences from src to dst. dst-lock must be held.
 488  */
 489 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 490 {
 491         struct dma_resv_iter cursor;
 492         struct dma_resv_list *list;
 493         struct dma_fence *f, *excl;
 494
 495         dma_resv_assert_held(dst);
 496
 497         list = NULL;
 498         excl = NULL;
 499
 500         dma_resv_iter_begin(&cursor, src, true);
 501         dma_resv_for_each_fence_unlocked(&cursor, f) {
 502
 503                 if (dma_resv_iter_is_restarted(&cursor)) {
 504                         dma_resv_list_free(list);
 505                         dma_fence_put(excl);
 506
 507                         if (cursor.shared_count) {
 508                                 list = dma_resv_list_alloc(cursor.shared_count);
 509                                 if (!list) {
 510                                         dma_resv_iter_end(&cursor);
 511                                         return -ENOMEM;
 512                                 }
 513
 514                                 list->shared_count = 0;
 515
 516                         } else {
 517                                 list = NULL;
 518                         }
 519                         excl = NULL;
 520                 }
 521
 522                 dma_fence_get(f);
 523                 if (dma_resv_iter_is_exclusive(&cursor))
 524                         excl = f;
 525                 else
 526                         RCU_INIT_POINTER(list->shared[list->shared_count++], f);
 527         }
 528         dma_resv_iter_end(&cursor);
 529
 530         write_seqcount_begin(&dst->seq);
 531         excl = rcu_replace_pointer(dst->fence_excl, excl, dma_resv_held(dst));
 532         list = rcu_replace_pointer(dst->fence, list, dma_resv_held(dst));
 533         write_seqcount_end(&dst->seq);
 534
 535         dma_resv_list_free(list);
 536         dma_fence_put(excl);
 537
 538         return 0;
 539 }
 540 EXPORT_SYMBOL(dma_resv_copy_fences);
 541
 542 /**
 543  * dma_resv_get_fences - Get an object's shared and exclusive
 544  * fences without update side lock held
 545  * @obj: the reservation object
 546  * @fence_excl: the returned exclusive fence (or NULL)
 547  * @shared_count: the number of shared fences returned
 548  * @shared: the array of shared fence ptrs returned (array is krealloc'd to
 549  * the required size, and must be freed by caller)
 550  *
 551  * Retrieve all fences from the reservation object. If the pointer for the
 552  * exclusive fence is not specified the fence is put into the array of the
 553  * shared fences as well. Returns either zero or -ENOMEM.
 554  */
 555 int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **fence_excl,
 556                         unsigned int *shared_count, struct dma_fence ***shared)
 557 {
 558         struct dma_resv_iter cursor;
 559         struct dma_fence *fence;
 560
 561         *shared_count = 0;
 562         *shared = NULL;
 563
 564         if (fence_excl)
 565                 *fence_excl = NULL;
 566
 567         dma_resv_iter_begin(&cursor, obj, true);
 568         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 569
 570                 if (dma_resv_iter_is_restarted(&cursor)) {
 571                         unsigned int count;
 572
 573                         while (*shared_count)
 574                                 dma_fence_put((*shared)[--(*shared_count)]);
 575
 576                         if (fence_excl)
 577                                 dma_fence_put(*fence_excl);
 578
 579                         count = cursor.shared_count;
 580                         count += fence_excl ? 0 : 1;
 581
 582                         /* Eventually re-allocate the array */
 583                         *shared = krealloc_array(*shared, count,
 584                                                  sizeof(void *),
 585                                                  GFP_KERNEL);
 586                         if (count && !*shared) {
 587                                 dma_resv_iter_end(&cursor);
 588                                 return -ENOMEM;
 589                         }
 590                 }
 591
 592                 dma_fence_get(fence);
 593                 if (dma_resv_iter_is_exclusive(&cursor) && fence_excl)
 594                         *fence_excl = fence;
 595                 else
 596                         (*shared)[(*shared_count)++] = fence;
 597         }
 598         dma_resv_iter_end(&cursor);
 599
 600         return 0;
 601 }
 602 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
 603
 604 /**
 605  * dma_resv_wait_timeout - Wait on reservation's objects
 606  * shared and/or exclusive fences.
 607  * @obj: the reservation object
 608  * @wait_all: if true, wait on all fences, else wait on just exclusive fence
 609  * @intr: if true, do interruptible wait
 610  * @timeout: timeout value in jiffies or zero to return immediately
 611  *
 612  * Callers are not required to hold specific locks, but maybe hold
 613  * dma_resv_lock() already
 614  * RETURNS
 615  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
 616  * greater than zer on success.
 617  */
 618 long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
 619                            unsigned long timeout)
 620 {
 621         long ret = timeout ? timeout : 1;
 622         struct dma_resv_iter cursor;
 623         struct dma_fence *fence;
 624
 625         dma_resv_iter_begin(&cursor, obj, wait_all);
 626         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 627
 628                 ret = dma_fence_wait_timeout(fence, intr, ret);
 629                 if (ret <= 0) {
 630                         dma_resv_iter_end(&cursor);
 631                         return ret;
 632                 }
 633         }
 634         dma_resv_iter_end(&cursor);
 635
 636         return ret;
 637 }
 638 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 639
 640
 641 /**
 642  * dma_resv_test_signaled - Test if a reservation object's fences have been
 643  * signaled.
 644  * @obj: the reservation object
 645  * @test_all: if true, test all fences, otherwise only test the exclusive
 646  * fence
 647  *
 648  * Callers are not required to hold specific locks, but maybe hold
 649  * dma_resv_lock() already.
 650  *
 651  * RETURNS
 652  *
 653  * True if all fences signaled, else false.
 654  */
 655 bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all)
 656 {
 657         struct dma_resv_iter cursor;
 658         struct dma_fence *fence;
 659
 660         dma_resv_iter_begin(&cursor, obj, test_all);
 661         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 662                 dma_resv_iter_end(&cursor);
 663                 return false;
 664         }
 665         dma_resv_iter_end(&cursor);
 666         return true;
 667 }
 668 EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
 669
 670 /**
 671  * dma_resv_describe - Dump description of the resv object into seq_file
 672  * @obj: the reservation object
 673  * @seq: the seq_file to dump the description into
 674  *
 675  * Dump a textual description of the fences inside an dma_resv object into the
 676  * seq_file.
 677  */
 678 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
 679 {
 680         struct dma_resv_iter cursor;
 681         struct dma_fence *fence;
 682
 683         dma_resv_for_each_fence(&cursor, obj, true, fence) {
 684                 seq_printf(seq, "\t%s fence:",
 685                            dma_resv_iter_is_exclusive(&cursor) ?
 686                                 "Exclusive" : "Shared");
 687                 dma_fence_describe(fence, seq);
 688         }
 689 }
 690 EXPORT_SYMBOL_GPL(dma_resv_describe);
 691
 692 #if IS_ENABLED(CONFIG_LOCKDEP)
 693 static int __init dma_resv_lockdep(void)
 694 {
 695         struct mm_struct *mm = mm_alloc();
 696         struct ww_acquire_ctx ctx;
 697         struct dma_resv obj;
 698         struct address_space mapping;
 699         int ret;
 700
 701         if (!mm)
 702                 return -ENOMEM;
 703
 704         dma_resv_init(&obj);
 705         address_space_init_once(&mapping);
 706
 707         mmap_read_lock(mm);
 708         ww_acquire_init(&ctx, &reservation_ww_class);
 709         ret = dma_resv_lock(&obj, &ctx);
 710         if (ret == -EDEADLK)
 711                 dma_resv_lock_slow(&obj, &ctx);
 712         fs_reclaim_acquire(GFP_KERNEL);
 713         /* for unmap_mapping_range on trylocked buffer objects in shrinkers */
 714         i_mmap_lock_write(&mapping);
 715         i_mmap_unlock_write(&mapping);
 716 #ifdef CONFIG_MMU_NOTIFIER
 717         lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
 718         __dma_fence_might_wait();
 719         lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 720 #else
 721         __dma_fence_might_wait();
 722 #endif
 723         fs_reclaim_release(GFP_KERNEL);
 724         ww_mutex_unlock(&obj.lock);
 725         ww_acquire_fini(&ctx);
 726         mmap_read_unlock(mm);
 727
 728         mmput(mm);
 729
 730         return 0;
 731 }
 732 subsys_initcall(dma_resv_lockdep);
 733 #endif