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/dma-fence-array.h>
  38 #include <linux/export.h>
  39 #include <linux/mm.h>
  40 #include <linux/sched/mm.h>
  41 #include <linux/mmu_notifier.h>
  42 #include <linux/seq_file.h>
  43
  44 /**
  45  * DOC: Reservation Object Overview
  46  *
  47  * The reservation object provides a mechanism to manage a container of
  48  * dma_fence object associated with a resource. A reservation object
  49  * can have any number of fences attaches to it. Each fence carries an usage
  50  * parameter determining how the operation represented by the fence is using the
  51  * resource. The RCU mechanism is used to protect read access to fences from
  52  * locked write-side updates.
  53  *
  54  * See struct dma_resv for more details.
  55  */
  56
  57 DEFINE_WD_CLASS(reservation_ww_class);
  58 EXPORT_SYMBOL(reservation_ww_class);
  59
  60 /* Mask for the lower fence pointer bits */
  61 #define DMA_RESV_LIST_MASK      0x3
  62
  63 struct dma_resv_list {
  64         struct rcu_head rcu;
  65         u32 num_fences, max_fences;
  66         struct dma_fence __rcu *table[];
  67 };
  68
  69 /* Extract the fence and usage flags from an RCU protected entry in the list. */
  70 static void dma_resv_list_entry(struct dma_resv_list *list, unsigned int index,
  71                                 struct dma_resv *resv, struct dma_fence **fence,
  72                                 enum dma_resv_usage *usage)
  73 {
  74         long tmp;
  75
  76         tmp = (long)rcu_dereference_check(list->table[index],
  77                                           resv ? dma_resv_held(resv) : true);
  78         *fence = (struct dma_fence *)(tmp & ~DMA_RESV_LIST_MASK);
  79         if (usage)
  80                 *usage = tmp & DMA_RESV_LIST_MASK;
  81 }
  82
  83 /* Set the fence and usage flags at the specific index in the list. */
  84 static void dma_resv_list_set(struct dma_resv_list *list,
  85                               unsigned int index,
  86                               struct dma_fence *fence,
  87                               enum dma_resv_usage usage)
  88 {
  89         long tmp = ((long)fence) | usage;
  90
  91         RCU_INIT_POINTER(list->table[index], (struct dma_fence *)tmp);
  92 }
  93
  94 /*
  95  * Allocate a new dma_resv_list and make sure to correctly initialize
  96  * max_fences.
  97  */
  98 static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences)
  99 {
 100         struct dma_resv_list *list;
 101         size_t size;
 102
 103         /* Round up to the next kmalloc bucket size. */
 104         size = kmalloc_size_roundup(struct_size(list, table, max_fences));
 105
 106         list = kmalloc(size, GFP_KERNEL);
 107         if (!list)
 108                 return NULL;
 109
 110         /* Given the resulting bucket size, recalculated max_fences. */
 111         list->max_fences = (size - offsetof(typeof(*list), table)) /
 112                 sizeof(*list->table);
 113
 114         return list;
 115 }
 116
 117 /* Free a dma_resv_list and make sure to drop all references. */
 118 static void dma_resv_list_free(struct dma_resv_list *list)
 119 {
 120         unsigned int i;
 121
 122         if (!list)
 123                 return;
 124
 125         for (i = 0; i < list->num_fences; ++i) {
 126                 struct dma_fence *fence;
 127
 128                 dma_resv_list_entry(list, i, NULL, &fence, NULL);
 129                 dma_fence_put(fence);
 130         }
 131         kfree_rcu(list, rcu);
 132 }
 133
 134 /**
 135  * dma_resv_init - initialize a reservation object
 136  * @obj: the reservation object
 137  */
 138 void dma_resv_init(struct dma_resv *obj)
 139 {
 140         ww_mutex_init(&obj->lock, &reservation_ww_class);
 141
 142         RCU_INIT_POINTER(obj->fences, NULL);
 143 }
 144 EXPORT_SYMBOL(dma_resv_init);
 145
 146 /**
 147  * dma_resv_fini - destroys a reservation object
 148  * @obj: the reservation object
 149  */
 150 void dma_resv_fini(struct dma_resv *obj)
 151 {
 152         /*
 153          * This object should be dead and all references must have
 154          * been released to it, so no need to be protected with rcu.
 155          */
 156         dma_resv_list_free(rcu_dereference_protected(obj->fences, true));
 157         ww_mutex_destroy(&obj->lock);
 158 }
 159 EXPORT_SYMBOL(dma_resv_fini);
 160
 161 /* Dereference the fences while ensuring RCU rules */
 162 static inline struct dma_resv_list *dma_resv_fences_list(struct dma_resv *obj)
 163 {
 164         return rcu_dereference_check(obj->fences, dma_resv_held(obj));
 165 }
 166
 167 /**
 168  * dma_resv_reserve_fences - Reserve space to add fences to a dma_resv object.
 169  * @obj: reservation object
 170  * @num_fences: number of fences we want to add
 171  *
 172  * Should be called before dma_resv_add_fence().  Must be called with @obj
 173  * locked through dma_resv_lock().
 174  *
 175  * Note that the preallocated slots need to be re-reserved if @obj is unlocked
 176  * at any time before calling dma_resv_add_fence(). This is validated when
 177  * CONFIG_DEBUG_MUTEXES is enabled.
 178  *
 179  * RETURNS
 180  * Zero for success, or -errno
 181  */
 182 int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
 183 {
 184         struct dma_resv_list *old, *new;
 185         unsigned int i, j, k, max;
 186
 187         dma_resv_assert_held(obj);
 188
 189         /* Driver and component code should never call this function with
 190          * num_fences=0. If they do it usually points to bugs when calculating
 191          * the number of needed fences dynamically.
 192          */
 193         if (WARN_ON(!num_fences))
 194                 return -EINVAL;
 195
 196         old = dma_resv_fences_list(obj);
 197         if (old && old->max_fences) {
 198                 if ((old->num_fences + num_fences) <= old->max_fences)
 199                         return 0;
 200                 max = max(old->num_fences + num_fences, old->max_fences * 2);
 201         } else {
 202                 max = max(4ul, roundup_pow_of_two(num_fences));
 203         }
 204
 205         new = dma_resv_list_alloc(max);
 206         if (!new)
 207                 return -ENOMEM;
 208
 209         /*
 210          * no need to bump fence refcounts, rcu_read access
 211          * requires the use of kref_get_unless_zero, and the
 212          * references from the old struct are carried over to
 213          * the new.
 214          */
 215         for (i = 0, j = 0, k = max; i < (old ? old->num_fences : 0); ++i) {
 216                 enum dma_resv_usage usage;
 217                 struct dma_fence *fence;
 218
 219                 dma_resv_list_entry(old, i, obj, &fence, &usage);
 220                 if (dma_fence_is_signaled(fence))
 221                         RCU_INIT_POINTER(new->table[--k], fence);
 222                 else
 223                         dma_resv_list_set(new, j++, fence, usage);
 224         }
 225         new->num_fences = j;
 226
 227         /*
 228          * We are not changing the effective set of fences here so can
 229          * merely update the pointer to the new array; both existing
 230          * readers and new readers will see exactly the same set of
 231          * active (unsignaled) fences. Individual fences and the
 232          * old array are protected by RCU and so will not vanish under
 233          * the gaze of the rcu_read_lock() readers.
 234          */
 235         rcu_assign_pointer(obj->fences, new);
 236
 237         if (!old)
 238                 return 0;
 239
 240         /* Drop the references to the signaled fences */
 241         for (i = k; i < max; ++i) {
 242                 struct dma_fence *fence;
 243
 244                 fence = rcu_dereference_protected(new->table[i],
 245                                                   dma_resv_held(obj));
 246                 dma_fence_put(fence);
 247         }
 248         kfree_rcu(old, rcu);
 249
 250         return 0;
 251 }
 252 EXPORT_SYMBOL(dma_resv_reserve_fences);
 253
 254 #ifdef CONFIG_DEBUG_MUTEXES
 255 /**
 256  * dma_resv_reset_max_fences - reset fences for debugging
 257  * @obj: the dma_resv object to reset
 258  *
 259  * Reset the number of pre-reserved fence slots to test that drivers do
 260  * correct slot allocation using dma_resv_reserve_fences(). See also
 261  * &dma_resv_list.max_fences.
 262  */
 263 void dma_resv_reset_max_fences(struct dma_resv *obj)
 264 {
 265         struct dma_resv_list *fences = dma_resv_fences_list(obj);
 266
 267         dma_resv_assert_held(obj);
 268
 269         /* Test fence slot reservation */
 270         if (fences)
 271                 fences->max_fences = fences->num_fences;
 272 }
 273 EXPORT_SYMBOL(dma_resv_reset_max_fences);
 274 #endif
 275
 276 /**
 277  * dma_resv_add_fence - Add a fence to the dma_resv obj
 278  * @obj: the reservation object
 279  * @fence: the fence to add
 280  * @usage: how the fence is used, see enum dma_resv_usage
 281  *
 282  * Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
 283  * dma_resv_reserve_fences() has been called.
 284  *
 285  * See also &dma_resv.fence for a discussion of the semantics.
 286  */
 287 void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
 288                         enum dma_resv_usage usage)
 289 {
 290         struct dma_resv_list *fobj;
 291         struct dma_fence *old;
 292         unsigned int i, count;
 293
 294         dma_fence_get(fence);
 295
 296         dma_resv_assert_held(obj);
 297
 298         /* Drivers should not add containers here, instead add each fence
 299          * individually.
 300          */
 301         WARN_ON(dma_fence_is_container(fence));
 302
 303         fobj = dma_resv_fences_list(obj);
 304         count = fobj->num_fences;
 305
 306         for (i = 0; i < count; ++i) {
 307                 enum dma_resv_usage old_usage;
 308
 309                 dma_resv_list_entry(fobj, i, obj, &old, &old_usage);
 310                 if ((old->context == fence->context && old_usage >= usage &&
 311                      dma_fence_is_later_or_same(fence, old)) ||
 312                     dma_fence_is_signaled(old)) {
 313                         dma_resv_list_set(fobj, i, fence, usage);
 314                         dma_fence_put(old);
 315                         return;
 316                 }
 317         }
 318
 319         BUG_ON(fobj->num_fences >= fobj->max_fences);
 320         count++;
 321
 322         dma_resv_list_set(fobj, i, fence, usage);
 323         /* pointer update must be visible before we extend the num_fences */
 324         smp_store_mb(fobj->num_fences, count);
 325 }
 326 EXPORT_SYMBOL(dma_resv_add_fence);
 327
 328 /**
 329  * dma_resv_replace_fences - replace fences in the dma_resv obj
 330  * @obj: the reservation object
 331  * @context: the context of the fences to replace
 332  * @replacement: the new fence to use instead
 333  * @usage: how the new fence is used, see enum dma_resv_usage
 334  *
 335  * Replace fences with a specified context with a new fence. Only valid if the
 336  * operation represented by the original fence has no longer access to the
 337  * resources represented by the dma_resv object when the new fence completes.
 338  *
 339  * And example for using this is replacing a preemption fence with a page table
 340  * update fence which makes the resource inaccessible.
 341  */
 342 void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
 343                              struct dma_fence *replacement,
 344                              enum dma_resv_usage usage)
 345 {
 346         struct dma_resv_list *list;
 347         unsigned int i;
 348
 349         dma_resv_assert_held(obj);
 350
 351         list = dma_resv_fences_list(obj);
 352         for (i = 0; list && i < list->num_fences; ++i) {
 353                 struct dma_fence *old;
 354
 355                 dma_resv_list_entry(list, i, obj, &old, NULL);
 356                 if (old->context != context)
 357                         continue;
 358
 359                 dma_resv_list_set(list, i, dma_fence_get(replacement), usage);
 360                 dma_fence_put(old);
 361         }
 362 }
 363 EXPORT_SYMBOL(dma_resv_replace_fences);
 364
 365 /* Restart the unlocked iteration by initializing the cursor object. */
 366 static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
 367 {
 368         cursor->index = 0;
 369         cursor->num_fences = 0;
 370         cursor->fences = dma_resv_fences_list(cursor->obj);
 371         if (cursor->fences)
 372                 cursor->num_fences = cursor->fences->num_fences;
 373         cursor->is_restarted = true;
 374 }
 375
 376 /* Walk to the next not signaled fence and grab a reference to it */
 377 static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
 378 {
 379         if (!cursor->fences)
 380                 return;
 381
 382         do {
 383                 /* Drop the reference from the previous round */
 384                 dma_fence_put(cursor->fence);
 385
 386                 if (cursor->index >= cursor->num_fences) {
 387                         cursor->fence = NULL;
 388                         break;
 389
 390                 }
 391
 392                 dma_resv_list_entry(cursor->fences, cursor->index++,
 393                                     cursor->obj, &cursor->fence,
 394                                     &cursor->fence_usage);
 395                 cursor->fence = dma_fence_get_rcu(cursor->fence);
 396                 if (!cursor->fence) {
 397                         dma_resv_iter_restart_unlocked(cursor);
 398                         continue;
 399                 }
 400
 401                 if (!dma_fence_is_signaled(cursor->fence) &&
 402                     cursor->usage >= cursor->fence_usage)
 403                         break;
 404         } while (true);
 405 }
 406
 407 /**
 408  * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
 409  * @cursor: the cursor with the current position
 410  *
 411  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
 412  *
 413  * Beware that the iterator can be restarted.  Code which accumulates statistics
 414  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
 415  * this reason prefer the locked dma_resv_iter_first() whenever possible.
 416  *
 417  * Returns the first fence from an unlocked dma_resv obj.
 418  */
 419 struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
 420 {
 421         rcu_read_lock();
 422         do {
 423                 dma_resv_iter_restart_unlocked(cursor);
 424                 dma_resv_iter_walk_unlocked(cursor);
 425         } while (dma_resv_fences_list(cursor->obj) != cursor->fences);
 426         rcu_read_unlock();
 427
 428         return cursor->fence;
 429 }
 430 EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
 431
 432 /**
 433  * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
 434  * @cursor: the cursor with the current position
 435  *
 436  * Beware that the iterator can be restarted.  Code which accumulates statistics
 437  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
 438  * this reason prefer the locked dma_resv_iter_next() whenever possible.
 439  *
 440  * Returns the next fence from an unlocked dma_resv obj.
 441  */
 442 struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
 443 {
 444         bool restart;
 445
 446         rcu_read_lock();
 447         cursor->is_restarted = false;
 448         restart = dma_resv_fences_list(cursor->obj) != cursor->fences;
 449         do {
 450                 if (restart)
 451                         dma_resv_iter_restart_unlocked(cursor);
 452                 dma_resv_iter_walk_unlocked(cursor);
 453                 restart = true;
 454         } while (dma_resv_fences_list(cursor->obj) != cursor->fences);
 455         rcu_read_unlock();
 456
 457         return cursor->fence;
 458 }
 459 EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
 460
 461 /**
 462  * dma_resv_iter_first - first fence from a locked dma_resv object
 463  * @cursor: cursor to record the current position
 464  *
 465  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
 466  *
 467  * Return the first fence in the dma_resv object while holding the
 468  * &dma_resv.lock.
 469  */
 470 struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
 471 {
 472         struct dma_fence *fence;
 473
 474         dma_resv_assert_held(cursor->obj);
 475
 476         cursor->index = 0;
 477         cursor->fences = dma_resv_fences_list(cursor->obj);
 478
 479         fence = dma_resv_iter_next(cursor);
 480         cursor->is_restarted = true;
 481         return fence;
 482 }
 483 EXPORT_SYMBOL_GPL(dma_resv_iter_first);
 484
 485 /**
 486  * dma_resv_iter_next - next fence from a locked dma_resv object
 487  * @cursor: cursor to record the current position
 488  *
 489  * Return the next fences from the dma_resv object while holding the
 490  * &dma_resv.lock.
 491  */
 492 struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
 493 {
 494         struct dma_fence *fence;
 495
 496         dma_resv_assert_held(cursor->obj);
 497
 498         cursor->is_restarted = false;
 499
 500         do {
 501                 if (!cursor->fences ||
 502                     cursor->index >= cursor->fences->num_fences)
 503                         return NULL;
 504
 505                 dma_resv_list_entry(cursor->fences, cursor->index++,
 506                                     cursor->obj, &fence, &cursor->fence_usage);
 507         } while (cursor->fence_usage > cursor->usage);
 508
 509         return fence;
 510 }
 511 EXPORT_SYMBOL_GPL(dma_resv_iter_next);
 512
 513 /**
 514  * dma_resv_copy_fences - Copy all fences from src to dst.
 515  * @dst: the destination reservation object
 516  * @src: the source reservation object
 517  *
 518  * Copy all fences from src to dst. dst-lock must be held.
 519  */
 520 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 521 {
 522         struct dma_resv_iter cursor;
 523         struct dma_resv_list *list;
 524         struct dma_fence *f;
 525
 526         dma_resv_assert_held(dst);
 527
 528         list = NULL;
 529
 530         dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP);
 531         dma_resv_for_each_fence_unlocked(&cursor, f) {
 532
 533                 if (dma_resv_iter_is_restarted(&cursor)) {
 534                         dma_resv_list_free(list);
 535
 536                         list = dma_resv_list_alloc(cursor.num_fences);
 537                         if (!list) {
 538                                 dma_resv_iter_end(&cursor);
 539                                 return -ENOMEM;
 540                         }
 541                         list->num_fences = 0;
 542                 }
 543
 544                 dma_fence_get(f);
 545                 dma_resv_list_set(list, list->num_fences++, f,
 546                                   dma_resv_iter_usage(&cursor));
 547         }
 548         dma_resv_iter_end(&cursor);
 549
 550         list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
 551         dma_resv_list_free(list);
 552         return 0;
 553 }
 554 EXPORT_SYMBOL(dma_resv_copy_fences);
 555
 556 /**
 557  * dma_resv_get_fences - Get an object's fences
 558  * fences without update side lock held
 559  * @obj: the reservation object
 560  * @usage: controls which fences to include, see enum dma_resv_usage.
 561  * @num_fences: the number of fences returned
 562  * @fences: the array of fence ptrs returned (array is krealloc'd to the
 563  * required size, and must be freed by caller)
 564  *
 565  * Retrieve all fences from the reservation object.
 566  * Returns either zero or -ENOMEM.
 567  */
 568 int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
 569                         unsigned int *num_fences, struct dma_fence ***fences)
 570 {
 571         struct dma_resv_iter cursor;
 572         struct dma_fence *fence;
 573
 574         *num_fences = 0;
 575         *fences = NULL;
 576
 577         dma_resv_iter_begin(&cursor, obj, usage);
 578         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 579
 580                 if (dma_resv_iter_is_restarted(&cursor)) {
 581                         struct dma_fence **new_fences;
 582                         unsigned int count;
 583
 584                         while (*num_fences)
 585                                 dma_fence_put((*fences)[--(*num_fences)]);
 586
 587                         count = cursor.num_fences + 1;
 588
 589                         /* Eventually re-allocate the array */
 590                         new_fences = krealloc_array(*fences, count,
 591                                                     sizeof(void *),
 592                                                     GFP_KERNEL);
 593                         if (count && !new_fences) {
 594                                 kfree(*fences);
 595                                 *fences = NULL;
 596                                 *num_fences = 0;
 597                                 dma_resv_iter_end(&cursor);
 598                                 return -ENOMEM;
 599                         }
 600                         *fences = new_fences;
 601                 }
 602
 603                 (*fences)[(*num_fences)++] = dma_fence_get(fence);
 604         }
 605         dma_resv_iter_end(&cursor);
 606
 607         return 0;
 608 }
 609 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
 610
 611 /**
 612  * dma_resv_get_singleton - Get a single fence for all the fences
 613  * @obj: the reservation object
 614  * @usage: controls which fences to include, see enum dma_resv_usage.
 615  * @fence: the resulting fence
 616  *
 617  * Get a single fence representing all the fences inside the resv object.
 618  * Returns either 0 for success or -ENOMEM.
 619  *
 620  * Warning: This can't be used like this when adding the fence back to the resv
 621  * object since that can lead to stack corruption when finalizing the
 622  * dma_fence_array.
 623  *
 624  * Returns 0 on success and negative error values on failure.
 625  */
 626 int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
 627                            struct dma_fence **fence)
 628 {
 629         struct dma_fence_array *array;
 630         struct dma_fence **fences;
 631         unsigned count;
 632         int r;
 633
 634         r = dma_resv_get_fences(obj, usage, &count, &fences);
 635         if (r)
 636                 return r;
 637
 638         if (count == 0) {
 639                 *fence = NULL;
 640                 return 0;
 641         }
 642
 643         if (count == 1) {
 644                 *fence = fences[0];
 645                 kfree(fences);
 646                 return 0;
 647         }
 648
 649         array = dma_fence_array_create(count, fences,
 650                                        dma_fence_context_alloc(1),
 651                                        1, false);
 652         if (!array) {
 653                 while (count--)
 654                         dma_fence_put(fences[count]);
 655                 kfree(fences);
 656                 return -ENOMEM;
 657         }
 658
 659         *fence = &array->base;
 660         return 0;
 661 }
 662 EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
 663
 664 /**
 665  * dma_resv_wait_timeout - Wait on reservation's objects fences
 666  * @obj: the reservation object
 667  * @usage: controls which fences to include, see enum dma_resv_usage.
 668  * @intr: if true, do interruptible wait
 669  * @timeout: timeout value in jiffies or zero to return immediately
 670  *
 671  * Callers are not required to hold specific locks, but maybe hold
 672  * dma_resv_lock() already
 673  * RETURNS
 674  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
 675  * greater than zero on success.
 676  */
 677 long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
 678                            bool intr, unsigned long timeout)
 679 {
 680         long ret = timeout ? timeout : 1;
 681         struct dma_resv_iter cursor;
 682         struct dma_fence *fence;
 683
 684         dma_resv_iter_begin(&cursor, obj, usage);
 685         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 686
 687                 ret = dma_fence_wait_timeout(fence, intr, ret);
 688                 if (ret <= 0) {
 689                         dma_resv_iter_end(&cursor);
 690                         return ret;
 691                 }
 692         }
 693         dma_resv_iter_end(&cursor);
 694
 695         return ret;
 696 }
 697 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 698
 699 /**
 700  * dma_resv_set_deadline - Set a deadline on reservation's objects fences
 701  * @obj: the reservation object
 702  * @usage: controls which fences to include, see enum dma_resv_usage.
 703  * @deadline: the requested deadline (MONOTONIC)
 704  *
 705  * May be called without holding the dma_resv lock.  Sets @deadline on
 706  * all fences filtered by @usage.
 707  */
 708 void dma_resv_set_deadline(struct dma_resv *obj, enum dma_resv_usage usage,
 709                            ktime_t deadline)
 710 {
 711         struct dma_resv_iter cursor;
 712         struct dma_fence *fence;
 713
 714         dma_resv_iter_begin(&cursor, obj, usage);
 715         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 716                 dma_fence_set_deadline(fence, deadline);
 717         }
 718         dma_resv_iter_end(&cursor);
 719 }
 720 EXPORT_SYMBOL_GPL(dma_resv_set_deadline);
 721
 722 /**
 723  * dma_resv_test_signaled - Test if a reservation object's fences have been
 724  * signaled.
 725  * @obj: the reservation object
 726  * @usage: controls which fences to include, see enum dma_resv_usage.
 727  *
 728  * Callers are not required to hold specific locks, but maybe hold
 729  * dma_resv_lock() already.
 730  *
 731  * RETURNS
 732  *
 733  * True if all fences signaled, else false.
 734  */
 735 bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage)
 736 {
 737         struct dma_resv_iter cursor;
 738         struct dma_fence *fence;
 739
 740         dma_resv_iter_begin(&cursor, obj, usage);
 741         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 742                 dma_resv_iter_end(&cursor);
 743                 return false;
 744         }
 745         dma_resv_iter_end(&cursor);
 746         return true;
 747 }
 748 EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
 749
 750 /**
 751  * dma_resv_describe - Dump description of the resv object into seq_file
 752  * @obj: the reservation object
 753  * @seq: the seq_file to dump the description into
 754  *
 755  * Dump a textual description of the fences inside an dma_resv object into the
 756  * seq_file.
 757  */
 758 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
 759 {
 760         static const char *usage[] = { "kernel", "write", "read", "bookkeep" };
 761         struct dma_resv_iter cursor;
 762         struct dma_fence *fence;
 763
 764         dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
 765                 seq_printf(seq, "\t%s fence:",
 766                            usage[dma_resv_iter_usage(&cursor)]);
 767                 dma_fence_describe(fence, seq);
 768         }
 769 }
 770 EXPORT_SYMBOL_GPL(dma_resv_describe);
 771
 772 #if IS_ENABLED(CONFIG_LOCKDEP)
 773 static int __init dma_resv_lockdep(void)
 774 {
 775         struct mm_struct *mm = mm_alloc();
 776         struct ww_acquire_ctx ctx;
 777         struct dma_resv obj;
 778         struct address_space mapping;
 779         int ret;
 780
 781         if (!mm)
 782                 return -ENOMEM;
 783
 784         dma_resv_init(&obj);
 785         address_space_init_once(&mapping);
 786
 787         mmap_read_lock(mm);
 788         ww_acquire_init(&ctx, &reservation_ww_class);
 789         ret = dma_resv_lock(&obj, &ctx);
 790         if (ret == -EDEADLK)
 791                 dma_resv_lock_slow(&obj, &ctx);
 792         fs_reclaim_acquire(GFP_KERNEL);
 793         /* for unmap_mapping_range on trylocked buffer objects in shrinkers */
 794         i_mmap_lock_write(&mapping);
 795         i_mmap_unlock_write(&mapping);
 796 #ifdef CONFIG_MMU_NOTIFIER
 797         lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
 798         __dma_fence_might_wait();
 799         lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 800 #else
 801         __dma_fence_might_wait();
 802 #endif
 803         fs_reclaim_release(GFP_KERNEL);
 804         ww_mutex_unlock(&obj.lock);
 805         ww_acquire_fini(&ctx);
 806         mmap_read_unlock(mm);
 807
 808         mmput(mm);
 809
 810         return 0;
 811 }
 812 subsys_initcall(dma_resv_lockdep);
 813 #endif