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_later(fence, old)) ||
 300                     dma_fence_is_signaled(old)) {
 301                         dma_resv_list_set(fobj, i, fence, usage);
 302                         dma_fence_put(old);
 303                         return;
 304                 }
 305         }
 306
 307         BUG_ON(fobj->num_fences >= fobj->max_fences);
 308         count++;
 309
 310         dma_resv_list_set(fobj, i, fence, usage);
 311         /* pointer update must be visible before we extend the num_fences */
 312         smp_store_mb(fobj->num_fences, count);
 313 }
 314 EXPORT_SYMBOL(dma_resv_add_fence);
 315
 316 /**
 317  * dma_resv_replace_fences - replace fences in the dma_resv obj
 318  * @obj: the reservation object
 319  * @context: the context of the fences to replace
 320  * @replacement: the new fence to use instead
 321  * @usage: how the new fence is used, see enum dma_resv_usage
 322  *
 323  * Replace fences with a specified context with a new fence. Only valid if the
 324  * operation represented by the original fence has no longer access to the
 325  * resources represented by the dma_resv object when the new fence completes.
 326  *
 327  * And example for using this is replacing a preemption fence with a page table
 328  * update fence which makes the resource inaccessible.
 329  */
 330 void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
 331                              struct dma_fence *replacement,
 332                              enum dma_resv_usage usage)
 333 {
 334         struct dma_resv_list *list;
 335         unsigned int i;
 336
 337         dma_resv_assert_held(obj);
 338
 339         list = dma_resv_fences_list(obj);
 340         for (i = 0; list && i < list->num_fences; ++i) {
 341                 struct dma_fence *old;
 342
 343                 dma_resv_list_entry(list, i, obj, &old, NULL);
 344                 if (old->context != context)
 345                         continue;
 346
 347                 dma_resv_list_set(list, i, dma_fence_get(replacement), usage);
 348                 dma_fence_put(old);
 349         }
 350 }
 351 EXPORT_SYMBOL(dma_resv_replace_fences);
 352
 353 /* Restart the unlocked iteration by initializing the cursor object. */
 354 static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
 355 {
 356         cursor->index = 0;
 357         cursor->num_fences = 0;
 358         cursor->fences = dma_resv_fences_list(cursor->obj);
 359         if (cursor->fences)
 360                 cursor->num_fences = cursor->fences->num_fences;
 361         cursor->is_restarted = true;
 362 }
 363
 364 /* Walk to the next not signaled fence and grab a reference to it */
 365 static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
 366 {
 367         if (!cursor->fences)
 368                 return;
 369
 370         do {
 371                 /* Drop the reference from the previous round */
 372                 dma_fence_put(cursor->fence);
 373
 374                 if (cursor->index >= cursor->num_fences) {
 375                         cursor->fence = NULL;
 376                         break;
 377
 378                 }
 379
 380                 dma_resv_list_entry(cursor->fences, cursor->index++,
 381                                     cursor->obj, &cursor->fence,
 382                                     &cursor->fence_usage);
 383                 cursor->fence = dma_fence_get_rcu(cursor->fence);
 384                 if (!cursor->fence) {
 385                         dma_resv_iter_restart_unlocked(cursor);
 386                         continue;
 387                 }
 388
 389                 if (!dma_fence_is_signaled(cursor->fence) &&
 390                     cursor->usage >= cursor->fence_usage)
 391                         break;
 392         } while (true);
 393 }
 394
 395 /**
 396  * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
 397  * @cursor: the cursor with the current position
 398  *
 399  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
 400  *
 401  * Beware that the iterator can be restarted.  Code which accumulates statistics
 402  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
 403  * this reason prefer the locked dma_resv_iter_first() whenver possible.
 404  *
 405  * Returns the first fence from an unlocked dma_resv obj.
 406  */
 407 struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
 408 {
 409         rcu_read_lock();
 410         do {
 411                 dma_resv_iter_restart_unlocked(cursor);
 412                 dma_resv_iter_walk_unlocked(cursor);
 413         } while (dma_resv_fences_list(cursor->obj) != cursor->fences);
 414         rcu_read_unlock();
 415
 416         return cursor->fence;
 417 }
 418 EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
 419
 420 /**
 421  * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
 422  * @cursor: the cursor with the current position
 423  *
 424  * Beware that the iterator can be restarted.  Code which accumulates statistics
 425  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
 426  * this reason prefer the locked dma_resv_iter_next() whenver possible.
 427  *
 428  * Returns the next fence from an unlocked dma_resv obj.
 429  */
 430 struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
 431 {
 432         bool restart;
 433
 434         rcu_read_lock();
 435         cursor->is_restarted = false;
 436         restart = dma_resv_fences_list(cursor->obj) != cursor->fences;
 437         do {
 438                 if (restart)
 439                         dma_resv_iter_restart_unlocked(cursor);
 440                 dma_resv_iter_walk_unlocked(cursor);
 441                 restart = true;
 442         } while (dma_resv_fences_list(cursor->obj) != cursor->fences);
 443         rcu_read_unlock();
 444
 445         return cursor->fence;
 446 }
 447 EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
 448
 449 /**
 450  * dma_resv_iter_first - first fence from a locked dma_resv object
 451  * @cursor: cursor to record the current position
 452  *
 453  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
 454  *
 455  * Return the first fence in the dma_resv object while holding the
 456  * &dma_resv.lock.
 457  */
 458 struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
 459 {
 460         struct dma_fence *fence;
 461
 462         dma_resv_assert_held(cursor->obj);
 463
 464         cursor->index = 0;
 465         cursor->fences = dma_resv_fences_list(cursor->obj);
 466
 467         fence = dma_resv_iter_next(cursor);
 468         cursor->is_restarted = true;
 469         return fence;
 470 }
 471 EXPORT_SYMBOL_GPL(dma_resv_iter_first);
 472
 473 /**
 474  * dma_resv_iter_next - next fence from a locked dma_resv object
 475  * @cursor: cursor to record the current position
 476  *
 477  * Return the next fences from the dma_resv object while holding the
 478  * &dma_resv.lock.
 479  */
 480 struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
 481 {
 482         struct dma_fence *fence;
 483
 484         dma_resv_assert_held(cursor->obj);
 485
 486         cursor->is_restarted = false;
 487
 488         do {
 489                 if (!cursor->fences ||
 490                     cursor->index >= cursor->fences->num_fences)
 491                         return NULL;
 492
 493                 dma_resv_list_entry(cursor->fences, cursor->index++,
 494                                     cursor->obj, &fence, &cursor->fence_usage);
 495         } while (cursor->fence_usage > cursor->usage);
 496
 497         return fence;
 498 }
 499 EXPORT_SYMBOL_GPL(dma_resv_iter_next);
 500
 501 /**
 502  * dma_resv_copy_fences - Copy all fences from src to dst.
 503  * @dst: the destination reservation object
 504  * @src: the source reservation object
 505  *
 506  * Copy all fences from src to dst. dst-lock must be held.
 507  */
 508 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 509 {
 510         struct dma_resv_iter cursor;
 511         struct dma_resv_list *list;
 512         struct dma_fence *f;
 513
 514         dma_resv_assert_held(dst);
 515
 516         list = NULL;
 517
 518         dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP);
 519         dma_resv_for_each_fence_unlocked(&cursor, f) {
 520
 521                 if (dma_resv_iter_is_restarted(&cursor)) {
 522                         dma_resv_list_free(list);
 523
 524                         list = dma_resv_list_alloc(cursor.num_fences);
 525                         if (!list) {
 526                                 dma_resv_iter_end(&cursor);
 527                                 return -ENOMEM;
 528                         }
 529                         list->num_fences = 0;
 530                 }
 531
 532                 dma_fence_get(f);
 533                 dma_resv_list_set(list, list->num_fences++, f,
 534                                   dma_resv_iter_usage(&cursor));
 535         }
 536         dma_resv_iter_end(&cursor);
 537
 538         list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
 539         dma_resv_list_free(list);
 540         return 0;
 541 }
 542 EXPORT_SYMBOL(dma_resv_copy_fences);
 543
 544 /**
 545  * dma_resv_get_fences - Get an object's fences
 546  * fences without update side lock held
 547  * @obj: the reservation object
 548  * @usage: controls which fences to include, see enum dma_resv_usage.
 549  * @num_fences: the number of fences returned
 550  * @fences: the array of fence ptrs returned (array is krealloc'd to the
 551  * required size, and must be freed by caller)
 552  *
 553  * Retrieve all fences from the reservation object.
 554  * Returns either zero or -ENOMEM.
 555  */
 556 int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
 557                         unsigned int *num_fences, struct dma_fence ***fences)
 558 {
 559         struct dma_resv_iter cursor;
 560         struct dma_fence *fence;
 561
 562         *num_fences = 0;
 563         *fences = NULL;
 564
 565         dma_resv_iter_begin(&cursor, obj, usage);
 566         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 567
 568                 if (dma_resv_iter_is_restarted(&cursor)) {
 569                         unsigned int count;
 570
 571                         while (*num_fences)
 572                                 dma_fence_put((*fences)[--(*num_fences)]);
 573
 574                         count = cursor.num_fences + 1;
 575
 576                         /* Eventually re-allocate the array */
 577                         *fences = krealloc_array(*fences, count,
 578                                                  sizeof(void *),
 579                                                  GFP_KERNEL);
 580                         if (count && !*fences) {
 581                                 dma_resv_iter_end(&cursor);
 582                                 return -ENOMEM;
 583                         }
 584                 }
 585
 586                 (*fences)[(*num_fences)++] = dma_fence_get(fence);
 587         }
 588         dma_resv_iter_end(&cursor);
 589
 590         return 0;
 591 }
 592 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
 593
 594 /**
 595  * dma_resv_get_singleton - Get a single fence for all the fences
 596  * @obj: the reservation object
 597  * @usage: controls which fences to include, see enum dma_resv_usage.
 598  * @fence: the resulting fence
 599  *
 600  * Get a single fence representing all the fences inside the resv object.
 601  * Returns either 0 for success or -ENOMEM.
 602  *
 603  * Warning: This can't be used like this when adding the fence back to the resv
 604  * object since that can lead to stack corruption when finalizing the
 605  * dma_fence_array.
 606  *
 607  * Returns 0 on success and negative error values on failure.
 608  */
 609 int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
 610                            struct dma_fence **fence)
 611 {
 612         struct dma_fence_array *array;
 613         struct dma_fence **fences;
 614         unsigned count;
 615         int r;
 616
 617         r = dma_resv_get_fences(obj, usage, &count, &fences);
 618         if (r)
 619                 return r;
 620
 621         if (count == 0) {
 622                 *fence = NULL;
 623                 return 0;
 624         }
 625
 626         if (count == 1) {
 627                 *fence = fences[0];
 628                 kfree(fences);
 629                 return 0;
 630         }
 631
 632         array = dma_fence_array_create(count, fences,
 633                                        dma_fence_context_alloc(1),
 634                                        1, false);
 635         if (!array) {
 636                 while (count--)
 637                         dma_fence_put(fences[count]);
 638                 kfree(fences);
 639                 return -ENOMEM;
 640         }
 641
 642         *fence = &array->base;
 643         return 0;
 644 }
 645 EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
 646
 647 /**
 648  * dma_resv_wait_timeout - Wait on reservation's objects fences
 649  * @obj: the reservation object
 650  * @usage: controls which fences to include, see enum dma_resv_usage.
 651  * @intr: if true, do interruptible wait
 652  * @timeout: timeout value in jiffies or zero to return immediately
 653  *
 654  * Callers are not required to hold specific locks, but maybe hold
 655  * dma_resv_lock() already
 656  * RETURNS
 657  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
 658  * greater than zer on success.
 659  */
 660 long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
 661                            bool intr, unsigned long timeout)
 662 {
 663         long ret = timeout ? timeout : 1;
 664         struct dma_resv_iter cursor;
 665         struct dma_fence *fence;
 666
 667         dma_resv_iter_begin(&cursor, obj, usage);
 668         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 669
 670                 ret = dma_fence_wait_timeout(fence, intr, ret);
 671                 if (ret <= 0) {
 672                         dma_resv_iter_end(&cursor);
 673                         return ret;
 674                 }
 675         }
 676         dma_resv_iter_end(&cursor);
 677
 678         return ret;
 679 }
 680 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 681
 682
 683 /**
 684  * dma_resv_test_signaled - Test if a reservation object's fences have been
 685  * signaled.
 686  * @obj: the reservation object
 687  * @usage: controls which fences to include, see enum dma_resv_usage.
 688  *
 689  * Callers are not required to hold specific locks, but maybe hold
 690  * dma_resv_lock() already.
 691  *
 692  * RETURNS
 693  *
 694  * True if all fences signaled, else false.
 695  */
 696 bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage)
 697 {
 698         struct dma_resv_iter cursor;
 699         struct dma_fence *fence;
 700
 701         dma_resv_iter_begin(&cursor, obj, usage);
 702         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 703                 dma_resv_iter_end(&cursor);
 704                 return false;
 705         }
 706         dma_resv_iter_end(&cursor);
 707         return true;
 708 }
 709 EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
 710
 711 /**
 712  * dma_resv_describe - Dump description of the resv object into seq_file
 713  * @obj: the reservation object
 714  * @seq: the seq_file to dump the description into
 715  *
 716  * Dump a textual description of the fences inside an dma_resv object into the
 717  * seq_file.
 718  */
 719 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
 720 {
 721         static const char *usage[] = { "kernel", "write", "read", "bookkeep" };
 722         struct dma_resv_iter cursor;
 723         struct dma_fence *fence;
 724
 725         dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
 726                 seq_printf(seq, "\t%s fence:",
 727                            usage[dma_resv_iter_usage(&cursor)]);
 728                 dma_fence_describe(fence, seq);
 729         }
 730 }
 731 EXPORT_SYMBOL_GPL(dma_resv_describe);
 732
 733 #if IS_ENABLED(CONFIG_LOCKDEP)
 734 static int __init dma_resv_lockdep(void)
 735 {
 736         struct mm_struct *mm = mm_alloc();
 737         struct ww_acquire_ctx ctx;
 738         struct dma_resv obj;
 739         struct address_space mapping;
 740         int ret;
 741
 742         if (!mm)
 743                 return -ENOMEM;
 744
 745         dma_resv_init(&obj);
 746         address_space_init_once(&mapping);
 747
 748         mmap_read_lock(mm);
 749         ww_acquire_init(&ctx, &reservation_ww_class);
 750         ret = dma_resv_lock(&obj, &ctx);
 751         if (ret == -EDEADLK)
 752                 dma_resv_lock_slow(&obj, &ctx);
 753         fs_reclaim_acquire(GFP_KERNEL);
 754         /* for unmap_mapping_range on trylocked buffer objects in shrinkers */
 755         i_mmap_lock_write(&mapping);
 756         i_mmap_unlock_write(&mapping);
 757 #ifdef CONFIG_MMU_NOTIFIER
 758         lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
 759         __dma_fence_might_wait();
 760         lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 761 #else
 762         __dma_fence_might_wait();
 763 #endif
 764         fs_reclaim_release(GFP_KERNEL);
 765         ww_mutex_unlock(&obj.lock);
 766         ww_acquire_fini(&ctx);
 767         mmap_read_unlock(mm);
 768
 769         mmput(mm);
 770
 771         return 0;
 772 }
 773 subsys_initcall(dma_resv_lockdep);
 774 #endif