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         old = dma_resv_fences_list(obj);
 190         if (old && old->max_fences) {
 191                 if ((old->num_fences + num_fences) <= old->max_fences)
 192                         return 0;
 193                 max = max(old->num_fences + num_fences, old->max_fences * 2);
 194         } else {
 195                 max = max(4ul, roundup_pow_of_two(num_fences));
 196         }
 197
 198         new = dma_resv_list_alloc(max);
 199         if (!new)
 200                 return -ENOMEM;
 201
 202         /*
 203          * no need to bump fence refcounts, rcu_read access
 204          * requires the use of kref_get_unless_zero, and the
 205          * references from the old struct are carried over to
 206          * the new.
 207          */
 208         for (i = 0, j = 0, k = max; i < (old ? old->num_fences : 0); ++i) {
 209                 enum dma_resv_usage usage;
 210                 struct dma_fence *fence;
 211
 212                 dma_resv_list_entry(old, i, obj, &fence, &usage);
 213                 if (dma_fence_is_signaled(fence))
 214                         RCU_INIT_POINTER(new->table[--k], fence);
 215                 else
 216                         dma_resv_list_set(new, j++, fence, usage);
 217         }
 218         new->num_fences = j;
 219
 220         /*
 221          * We are not changing the effective set of fences here so can
 222          * merely update the pointer to the new array; both existing
 223          * readers and new readers will see exactly the same set of
 224          * active (unsignaled) fences. Individual fences and the
 225          * old array are protected by RCU and so will not vanish under
 226          * the gaze of the rcu_read_lock() readers.
 227          */
 228         rcu_assign_pointer(obj->fences, new);
 229
 230         if (!old)
 231                 return 0;
 232
 233         /* Drop the references to the signaled fences */
 234         for (i = k; i < max; ++i) {
 235                 struct dma_fence *fence;
 236
 237                 fence = rcu_dereference_protected(new->table[i],
 238                                                   dma_resv_held(obj));
 239                 dma_fence_put(fence);
 240         }
 241         kfree_rcu(old, rcu);
 242
 243         return 0;
 244 }
 245 EXPORT_SYMBOL(dma_resv_reserve_fences);
 246
 247 #ifdef CONFIG_DEBUG_MUTEXES
 248 /**
 249  * dma_resv_reset_max_fences - reset fences for debugging
 250  * @obj: the dma_resv object to reset
 251  *
 252  * Reset the number of pre-reserved fence slots to test that drivers do
 253  * correct slot allocation using dma_resv_reserve_fences(). See also
 254  * &dma_resv_list.max_fences.
 255  */
 256 void dma_resv_reset_max_fences(struct dma_resv *obj)
 257 {
 258         struct dma_resv_list *fences = dma_resv_fences_list(obj);
 259
 260         dma_resv_assert_held(obj);
 261
 262         /* Test fence slot reservation */
 263         if (fences)
 264                 fences->max_fences = fences->num_fences;
 265 }
 266 EXPORT_SYMBOL(dma_resv_reset_max_fences);
 267 #endif
 268
 269 /**
 270  * dma_resv_add_fence - Add a fence to the dma_resv obj
 271  * @obj: the reservation object
 272  * @fence: the fence to add
 273  * @usage: how the fence is used, see enum dma_resv_usage
 274  *
 275  * Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
 276  * dma_resv_reserve_fences() has been called.
 277  *
 278  * See also &dma_resv.fence for a discussion of the semantics.
 279  */
 280 void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
 281                         enum dma_resv_usage usage)
 282 {
 283         struct dma_resv_list *fobj;
 284         struct dma_fence *old;
 285         unsigned int i, count;
 286
 287         dma_fence_get(fence);
 288
 289         dma_resv_assert_held(obj);
 290
 291         /* Drivers should not add containers here, instead add each fence
 292          * individually.
 293          */
 294         WARN_ON(dma_fence_is_container(fence));
 295
 296         fobj = dma_resv_fences_list(obj);
 297         count = fobj->num_fences;
 298
 299         for (i = 0; i < count; ++i) {
 300                 enum dma_resv_usage old_usage;
 301
 302                 dma_resv_list_entry(fobj, i, obj, &old, &old_usage);
 303                 if ((old->context == fence->context && old_usage >= usage &&
 304                      dma_fence_is_later(fence, old)) ||
 305                     dma_fence_is_signaled(old)) {
 306                         dma_resv_list_set(fobj, i, fence, usage);
 307                         dma_fence_put(old);
 308                         return;
 309                 }
 310         }
 311
 312         BUG_ON(fobj->num_fences >= fobj->max_fences);
 313         count++;
 314
 315         dma_resv_list_set(fobj, i, fence, usage);
 316         /* pointer update must be visible before we extend the num_fences */
 317         smp_store_mb(fobj->num_fences, count);
 318 }
 319 EXPORT_SYMBOL(dma_resv_add_fence);
 320
 321 /**
 322  * dma_resv_replace_fences - replace fences in the dma_resv obj
 323  * @obj: the reservation object
 324  * @context: the context of the fences to replace
 325  * @replacement: the new fence to use instead
 326  * @usage: how the new fence is used, see enum dma_resv_usage
 327  *
 328  * Replace fences with a specified context with a new fence. Only valid if the
 329  * operation represented by the original fence has no longer access to the
 330  * resources represented by the dma_resv object when the new fence completes.
 331  *
 332  * And example for using this is replacing a preemption fence with a page table
 333  * update fence which makes the resource inaccessible.
 334  */
 335 void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
 336                              struct dma_fence *replacement,
 337                              enum dma_resv_usage usage)
 338 {
 339         struct dma_resv_list *list;
 340         unsigned int i;
 341
 342         dma_resv_assert_held(obj);
 343
 344         list = dma_resv_fences_list(obj);
 345         for (i = 0; list && i < list->num_fences; ++i) {
 346                 struct dma_fence *old;
 347
 348                 dma_resv_list_entry(list, i, obj, &old, NULL);
 349                 if (old->context != context)
 350                         continue;
 351
 352                 dma_resv_list_set(list, i, dma_fence_get(replacement), usage);
 353                 dma_fence_put(old);
 354         }
 355 }
 356 EXPORT_SYMBOL(dma_resv_replace_fences);
 357
 358 /* Restart the unlocked iteration by initializing the cursor object. */
 359 static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
 360 {
 361         cursor->index = 0;
 362         cursor->num_fences = 0;
 363         cursor->fences = dma_resv_fences_list(cursor->obj);
 364         if (cursor->fences)
 365                 cursor->num_fences = cursor->fences->num_fences;
 366         cursor->is_restarted = true;
 367 }
 368
 369 /* Walk to the next not signaled fence and grab a reference to it */
 370 static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
 371 {
 372         if (!cursor->fences)
 373                 return;
 374
 375         do {
 376                 /* Drop the reference from the previous round */
 377                 dma_fence_put(cursor->fence);
 378
 379                 if (cursor->index >= cursor->num_fences) {
 380                         cursor->fence = NULL;
 381                         break;
 382
 383                 }
 384
 385                 dma_resv_list_entry(cursor->fences, cursor->index++,
 386                                     cursor->obj, &cursor->fence,
 387                                     &cursor->fence_usage);
 388                 cursor->fence = dma_fence_get_rcu(cursor->fence);
 389                 if (!cursor->fence) {
 390                         dma_resv_iter_restart_unlocked(cursor);
 391                         continue;
 392                 }
 393
 394                 if (!dma_fence_is_signaled(cursor->fence) &&
 395                     cursor->usage >= cursor->fence_usage)
 396                         break;
 397         } while (true);
 398 }
 399
 400 /**
 401  * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
 402  * @cursor: the cursor with the current position
 403  *
 404  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
 405  *
 406  * Beware that the iterator can be restarted.  Code which accumulates statistics
 407  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
 408  * this reason prefer the locked dma_resv_iter_first() whenver possible.
 409  *
 410  * Returns the first fence from an unlocked dma_resv obj.
 411  */
 412 struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
 413 {
 414         rcu_read_lock();
 415         do {
 416                 dma_resv_iter_restart_unlocked(cursor);
 417                 dma_resv_iter_walk_unlocked(cursor);
 418         } while (dma_resv_fences_list(cursor->obj) != cursor->fences);
 419         rcu_read_unlock();
 420
 421         return cursor->fence;
 422 }
 423 EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
 424
 425 /**
 426  * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
 427  * @cursor: the cursor with the current position
 428  *
 429  * Beware that the iterator can be restarted.  Code which accumulates statistics
 430  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
 431  * this reason prefer the locked dma_resv_iter_next() whenver possible.
 432  *
 433  * Returns the next fence from an unlocked dma_resv obj.
 434  */
 435 struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
 436 {
 437         bool restart;
 438
 439         rcu_read_lock();
 440         cursor->is_restarted = false;
 441         restart = dma_resv_fences_list(cursor->obj) != cursor->fences;
 442         do {
 443                 if (restart)
 444                         dma_resv_iter_restart_unlocked(cursor);
 445                 dma_resv_iter_walk_unlocked(cursor);
 446                 restart = true;
 447         } while (dma_resv_fences_list(cursor->obj) != cursor->fences);
 448         rcu_read_unlock();
 449
 450         return cursor->fence;
 451 }
 452 EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
 453
 454 /**
 455  * dma_resv_iter_first - first fence from a locked dma_resv object
 456  * @cursor: cursor to record the current position
 457  *
 458  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
 459  *
 460  * Return the first fence in the dma_resv object while holding the
 461  * &dma_resv.lock.
 462  */
 463 struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
 464 {
 465         struct dma_fence *fence;
 466
 467         dma_resv_assert_held(cursor->obj);
 468
 469         cursor->index = 0;
 470         cursor->fences = dma_resv_fences_list(cursor->obj);
 471
 472         fence = dma_resv_iter_next(cursor);
 473         cursor->is_restarted = true;
 474         return fence;
 475 }
 476 EXPORT_SYMBOL_GPL(dma_resv_iter_first);
 477
 478 /**
 479  * dma_resv_iter_next - next fence from a locked dma_resv object
 480  * @cursor: cursor to record the current position
 481  *
 482  * Return the next fences from the dma_resv object while holding the
 483  * &dma_resv.lock.
 484  */
 485 struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
 486 {
 487         struct dma_fence *fence;
 488
 489         dma_resv_assert_held(cursor->obj);
 490
 491         cursor->is_restarted = false;
 492
 493         do {
 494                 if (!cursor->fences ||
 495                     cursor->index >= cursor->fences->num_fences)
 496                         return NULL;
 497
 498                 dma_resv_list_entry(cursor->fences, cursor->index++,
 499                                     cursor->obj, &fence, &cursor->fence_usage);
 500         } while (cursor->fence_usage > cursor->usage);
 501
 502         return fence;
 503 }
 504 EXPORT_SYMBOL_GPL(dma_resv_iter_next);
 505
 506 /**
 507  * dma_resv_copy_fences - Copy all fences from src to dst.
 508  * @dst: the destination reservation object
 509  * @src: the source reservation object
 510  *
 511  * Copy all fences from src to dst. dst-lock must be held.
 512  */
 513 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 514 {
 515         struct dma_resv_iter cursor;
 516         struct dma_resv_list *list;
 517         struct dma_fence *f;
 518
 519         dma_resv_assert_held(dst);
 520
 521         list = NULL;
 522
 523         dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP);
 524         dma_resv_for_each_fence_unlocked(&cursor, f) {
 525
 526                 if (dma_resv_iter_is_restarted(&cursor)) {
 527                         dma_resv_list_free(list);
 528
 529                         list = dma_resv_list_alloc(cursor.num_fences);
 530                         if (!list) {
 531                                 dma_resv_iter_end(&cursor);
 532                                 return -ENOMEM;
 533                         }
 534                         list->num_fences = 0;
 535                 }
 536
 537                 dma_fence_get(f);
 538                 dma_resv_list_set(list, list->num_fences++, f,
 539                                   dma_resv_iter_usage(&cursor));
 540         }
 541         dma_resv_iter_end(&cursor);
 542
 543         list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
 544         dma_resv_list_free(list);
 545         return 0;
 546 }
 547 EXPORT_SYMBOL(dma_resv_copy_fences);
 548
 549 /**
 550  * dma_resv_get_fences - Get an object's fences
 551  * fences without update side lock held
 552  * @obj: the reservation object
 553  * @usage: controls which fences to include, see enum dma_resv_usage.
 554  * @num_fences: the number of fences returned
 555  * @fences: the array of fence ptrs returned (array is krealloc'd to the
 556  * required size, and must be freed by caller)
 557  *
 558  * Retrieve all fences from the reservation object.
 559  * Returns either zero or -ENOMEM.
 560  */
 561 int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
 562                         unsigned int *num_fences, struct dma_fence ***fences)
 563 {
 564         struct dma_resv_iter cursor;
 565         struct dma_fence *fence;
 566
 567         *num_fences = 0;
 568         *fences = NULL;
 569
 570         dma_resv_iter_begin(&cursor, obj, usage);
 571         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 572
 573                 if (dma_resv_iter_is_restarted(&cursor)) {
 574                         unsigned int count;
 575
 576                         while (*num_fences)
 577                                 dma_fence_put((*fences)[--(*num_fences)]);
 578
 579                         count = cursor.num_fences + 1;
 580
 581                         /* Eventually re-allocate the array */
 582                         *fences = krealloc_array(*fences, count,
 583                                                  sizeof(void *),
 584                                                  GFP_KERNEL);
 585                         if (count && !*fences) {
 586                                 dma_resv_iter_end(&cursor);
 587                                 return -ENOMEM;
 588                         }
 589                 }
 590
 591                 (*fences)[(*num_fences)++] = dma_fence_get(fence);
 592         }
 593         dma_resv_iter_end(&cursor);
 594
 595         return 0;
 596 }
 597 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
 598
 599 /**
 600  * dma_resv_get_singleton - Get a single fence for all the fences
 601  * @obj: the reservation object
 602  * @usage: controls which fences to include, see enum dma_resv_usage.
 603  * @fence: the resulting fence
 604  *
 605  * Get a single fence representing all the fences inside the resv object.
 606  * Returns either 0 for success or -ENOMEM.
 607  *
 608  * Warning: This can't be used like this when adding the fence back to the resv
 609  * object since that can lead to stack corruption when finalizing the
 610  * dma_fence_array.
 611  *
 612  * Returns 0 on success and negative error values on failure.
 613  */
 614 int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
 615                            struct dma_fence **fence)
 616 {
 617         struct dma_fence_array *array;
 618         struct dma_fence **fences;
 619         unsigned count;
 620         int r;
 621
 622         r = dma_resv_get_fences(obj, usage, &count, &fences);
 623         if (r)
 624                 return r;
 625
 626         if (count == 0) {
 627                 *fence = NULL;
 628                 return 0;
 629         }
 630
 631         if (count == 1) {
 632                 *fence = fences[0];
 633                 kfree(fences);
 634                 return 0;
 635         }
 636
 637         array = dma_fence_array_create(count, fences,
 638                                        dma_fence_context_alloc(1),
 639                                        1, false);
 640         if (!array) {
 641                 while (count--)
 642                         dma_fence_put(fences[count]);
 643                 kfree(fences);
 644                 return -ENOMEM;
 645         }
 646
 647         *fence = &array->base;
 648         return 0;
 649 }
 650 EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
 651
 652 /**
 653  * dma_resv_wait_timeout - Wait on reservation's objects fences
 654  * @obj: the reservation object
 655  * @usage: controls which fences to include, see enum dma_resv_usage.
 656  * @intr: if true, do interruptible wait
 657  * @timeout: timeout value in jiffies or zero to return immediately
 658  *
 659  * Callers are not required to hold specific locks, but maybe hold
 660  * dma_resv_lock() already
 661  * RETURNS
 662  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
 663  * greater than zer on success.
 664  */
 665 long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
 666                            bool intr, unsigned long timeout)
 667 {
 668         long ret = timeout ? timeout : 1;
 669         struct dma_resv_iter cursor;
 670         struct dma_fence *fence;
 671
 672         dma_resv_iter_begin(&cursor, obj, usage);
 673         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 674
 675                 ret = dma_fence_wait_timeout(fence, intr, ret);
 676                 if (ret <= 0) {
 677                         dma_resv_iter_end(&cursor);
 678                         return ret;
 679                 }
 680         }
 681         dma_resv_iter_end(&cursor);
 682
 683         return ret;
 684 }
 685 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 686
 687 /**
 688  * dma_resv_set_deadline - Set a deadline on reservation's objects fences
 689  * @obj: the reservation object
 690  * @usage: controls which fences to include, see enum dma_resv_usage.
 691  * @deadline: the requested deadline (MONOTONIC)
 692  *
 693  * May be called without holding the dma_resv lock.  Sets @deadline on
 694  * all fences filtered by @usage.
 695  */
 696 void dma_resv_set_deadline(struct dma_resv *obj, enum dma_resv_usage usage,
 697                            ktime_t deadline)
 698 {
 699         struct dma_resv_iter cursor;
 700         struct dma_fence *fence;
 701
 702         dma_resv_iter_begin(&cursor, obj, usage);
 703         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 704                 dma_fence_set_deadline(fence, deadline);
 705         }
 706         dma_resv_iter_end(&cursor);
 707 }
 708 EXPORT_SYMBOL_GPL(dma_resv_set_deadline);
 709
 710 /**
 711  * dma_resv_test_signaled - Test if a reservation object's fences have been
 712  * signaled.
 713  * @obj: the reservation object
 714  * @usage: controls which fences to include, see enum dma_resv_usage.
 715  *
 716  * Callers are not required to hold specific locks, but maybe hold
 717  * dma_resv_lock() already.
 718  *
 719  * RETURNS
 720  *
 721  * True if all fences signaled, else false.
 722  */
 723 bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage)
 724 {
 725         struct dma_resv_iter cursor;
 726         struct dma_fence *fence;
 727
 728         dma_resv_iter_begin(&cursor, obj, usage);
 729         dma_resv_for_each_fence_unlocked(&cursor, fence) {
 730                 dma_resv_iter_end(&cursor);
 731                 return false;
 732         }
 733         dma_resv_iter_end(&cursor);
 734         return true;
 735 }
 736 EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
 737
 738 /**
 739  * dma_resv_describe - Dump description of the resv object into seq_file
 740  * @obj: the reservation object
 741  * @seq: the seq_file to dump the description into
 742  *
 743  * Dump a textual description of the fences inside an dma_resv object into the
 744  * seq_file.
 745  */
 746 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
 747 {
 748         static const char *usage[] = { "kernel", "write", "read", "bookkeep" };
 749         struct dma_resv_iter cursor;
 750         struct dma_fence *fence;
 751
 752         dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
 753                 seq_printf(seq, "\t%s fence:",
 754                            usage[dma_resv_iter_usage(&cursor)]);
 755                 dma_fence_describe(fence, seq);
 756         }
 757 }
 758 EXPORT_SYMBOL_GPL(dma_resv_describe);
 759
 760 #if IS_ENABLED(CONFIG_LOCKDEP)
 761 static int __init dma_resv_lockdep(void)
 762 {
 763         struct mm_struct *mm = mm_alloc();
 764         struct ww_acquire_ctx ctx;
 765         struct dma_resv obj;
 766         struct address_space mapping;
 767         int ret;
 768
 769         if (!mm)
 770                 return -ENOMEM;
 771
 772         dma_resv_init(&obj);
 773         address_space_init_once(&mapping);
 774
 775         mmap_read_lock(mm);
 776         ww_acquire_init(&ctx, &reservation_ww_class);
 777         ret = dma_resv_lock(&obj, &ctx);
 778         if (ret == -EDEADLK)
 779                 dma_resv_lock_slow(&obj, &ctx);
 780         fs_reclaim_acquire(GFP_KERNEL);
 781         /* for unmap_mapping_range on trylocked buffer objects in shrinkers */
 782         i_mmap_lock_write(&mapping);
 783         i_mmap_unlock_write(&mapping);
 784 #ifdef CONFIG_MMU_NOTIFIER
 785         lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
 786         __dma_fence_might_wait();
 787         lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 788 #else
 789         __dma_fence_might_wait();
 790 #endif
 791         fs_reclaim_release(GFP_KERNEL);
 792         ww_mutex_unlock(&obj.lock);
 793         ww_acquire_fini(&ctx);
 794         mmap_read_unlock(mm);
 795
 796         mmput(mm);
 797
 798         return 0;
 799 }
 800 subsys_initcall(dma_resv_lockdep);
 801 #endif