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