drivers/dma-buf/dma-resv.c

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