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         int ret;
 102
 103         if (!mm)
 104                 return -ENOMEM;
 105
 106         dma_resv_init(&obj);
 107
 108         mmap_read_lock(mm);
 109         ww_acquire_init(&ctx, &reservation_ww_class);
 110         ret = dma_resv_lock(&obj, &ctx);
 111         if (ret == -EDEADLK)
 112                 dma_resv_lock_slow(&obj, &ctx);
 113         fs_reclaim_acquire(GFP_KERNEL);
 114 #ifdef CONFIG_MMU_NOTIFIER
 115         lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
 116         __dma_fence_might_wait();
 117         lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 118 #else
 119         __dma_fence_might_wait();
 120 #endif
 121         fs_reclaim_release(GFP_KERNEL);
 122         ww_mutex_unlock(&obj.lock);
 123         ww_acquire_fini(&ctx);
 124         mmap_read_unlock(mm);
 125
 126         mmput(mm);
 127
 128         return 0;
 129 }
 130 subsys_initcall(dma_resv_lockdep);
 131 #endif
 132
 133 /**
 134  * dma_resv_init - initialize a reservation object
 135  * @obj: the reservation object
 136  */
 137 void dma_resv_init(struct dma_resv *obj)
 138 {
 139         ww_mutex_init(&obj->lock, &reservation_ww_class);
 140         seqcount_ww_mutex_init(&obj->seq, &obj->lock);
 141
 142         RCU_INIT_POINTER(obj->fence, NULL);
 143         RCU_INIT_POINTER(obj->fence_excl, NULL);
 144 }
 145 EXPORT_SYMBOL(dma_resv_init);
 146
 147 /**
 148  * dma_resv_fini - destroys a reservation object
 149  * @obj: the reservation object
 150  */
 151 void dma_resv_fini(struct dma_resv *obj)
 152 {
 153         struct dma_resv_list *fobj;
 154         struct dma_fence *excl;
 155
 156         /*
 157          * This object should be dead and all references must have
 158          * been released to it, so no need to be protected with rcu.
 159          */
 160         excl = rcu_dereference_protected(obj->fence_excl, 1);
 161         if (excl)
 162                 dma_fence_put(excl);
 163
 164         fobj = rcu_dereference_protected(obj->fence, 1);
 165         dma_resv_list_free(fobj);
 166         ww_mutex_destroy(&obj->lock);
 167 }
 168 EXPORT_SYMBOL(dma_resv_fini);
 169
 170 /**
 171  * dma_resv_reserve_shared - Reserve space to add shared fences to
 172  * a dma_resv.
 173  * @obj: reservation object
 174  * @num_fences: number of fences we want to add
 175  *
 176  * Should be called before dma_resv_add_shared_fence().  Must
 177  * be called with obj->lock held.
 178  *
 179  * RETURNS
 180  * Zero for success, or -errno
 181  */
 182 int dma_resv_reserve_shared(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_get_list(obj);
 190
 191         if (old && old->shared_max) {
 192                 if ((old->shared_count + num_fences) <= old->shared_max)
 193                         return 0;
 194                 else
 195                         max = max(old->shared_count + num_fences,
 196                                   old->shared_max * 2);
 197         } else {
 198                 max = 4;
 199         }
 200
 201         new = dma_resv_list_alloc(max);
 202         if (!new)
 203                 return -ENOMEM;
 204
 205         /*
 206          * no need to bump fence refcounts, rcu_read access
 207          * requires the use of kref_get_unless_zero, and the
 208          * references from the old struct are carried over to
 209          * the new.
 210          */
 211         for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
 212                 struct dma_fence *fence;
 213
 214                 fence = rcu_dereference_protected(old->shared[i],
 215                                                   dma_resv_held(obj));
 216                 if (dma_fence_is_signaled(fence))
 217                         RCU_INIT_POINTER(new->shared[--k], fence);
 218                 else
 219                         RCU_INIT_POINTER(new->shared[j++], fence);
 220         }
 221         new->shared_count = j;
 222
 223         /*
 224          * We are not changing the effective set of fences here so can
 225          * merely update the pointer to the new array; both existing
 226          * readers and new readers will see exactly the same set of
 227          * active (unsignaled) shared fences. Individual fences and the
 228          * old array are protected by RCU and so will not vanish under
 229          * the gaze of the rcu_read_lock() readers.
 230          */
 231         rcu_assign_pointer(obj->fence, new);
 232
 233         if (!old)
 234                 return 0;
 235
 236         /* Drop the references to the signaled fences */
 237         for (i = k; i < max; ++i) {
 238                 struct dma_fence *fence;
 239
 240                 fence = rcu_dereference_protected(new->shared[i],
 241                                                   dma_resv_held(obj));
 242                 dma_fence_put(fence);
 243         }
 244         kfree_rcu(old, rcu);
 245
 246         return 0;
 247 }
 248 EXPORT_SYMBOL(dma_resv_reserve_shared);
 249
 250 /**
 251  * dma_resv_add_shared_fence - Add a fence to a shared slot
 252  * @obj: the reservation object
 253  * @fence: the shared fence to add
 254  *
 255  * Add a fence to a shared slot, obj->lock must be held, and
 256  * dma_resv_reserve_shared() has been called.
 257  */
 258 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
 259 {
 260         struct dma_resv_list *fobj;
 261         struct dma_fence *old;
 262         unsigned int i, count;
 263
 264         dma_fence_get(fence);
 265
 266         dma_resv_assert_held(obj);
 267
 268         fobj = dma_resv_get_list(obj);
 269         count = fobj->shared_count;
 270
 271         write_seqcount_begin(&obj->seq);
 272
 273         for (i = 0; i < count; ++i) {
 274
 275                 old = rcu_dereference_protected(fobj->shared[i],
 276                                                 dma_resv_held(obj));
 277                 if (old->context == fence->context ||
 278                     dma_fence_is_signaled(old))
 279                         goto replace;
 280         }
 281
 282         BUG_ON(fobj->shared_count >= fobj->shared_max);
 283         old = NULL;
 284         count++;
 285
 286 replace:
 287         RCU_INIT_POINTER(fobj->shared[i], fence);
 288         /* pointer update must be visible before we extend the shared_count */
 289         smp_store_mb(fobj->shared_count, count);
 290
 291         write_seqcount_end(&obj->seq);
 292         dma_fence_put(old);
 293 }
 294 EXPORT_SYMBOL(dma_resv_add_shared_fence);
 295
 296 /**
 297  * dma_resv_add_excl_fence - Add an exclusive fence.
 298  * @obj: the reservation object
 299  * @fence: the shared fence to add
 300  *
 301  * Add a fence to the exclusive slot.  The obj->lock must be held.
 302  */
 303 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 304 {
 305         struct dma_fence *old_fence = dma_resv_get_excl(obj);
 306         struct dma_resv_list *old;
 307         u32 i = 0;
 308
 309         dma_resv_assert_held(obj);
 310
 311         old = dma_resv_get_list(obj);
 312         if (old)
 313                 i = old->shared_count;
 314
 315         if (fence)
 316                 dma_fence_get(fence);
 317
 318         write_seqcount_begin(&obj->seq);
 319         /* write_seqcount_begin provides the necessary memory barrier */
 320         RCU_INIT_POINTER(obj->fence_excl, fence);
 321         if (old)
 322                 old->shared_count = 0;
 323         write_seqcount_end(&obj->seq);
 324
 325         /* inplace update, no shared fences */
 326         while (i--)
 327                 dma_fence_put(rcu_dereference_protected(old->shared[i],
 328                                                 dma_resv_held(obj)));
 329
 330         dma_fence_put(old_fence);
 331 }
 332 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 333
 334 /**
 335 * dma_resv_copy_fences - Copy all fences from src to dst.
 336 * @dst: the destination reservation object
 337 * @src: the source reservation object
 338 *
 339 * Copy all fences from src to dst. dst-lock must be held.
 340 */
 341 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 342 {
 343         struct dma_resv_list *src_list, *dst_list;
 344         struct dma_fence *old, *new;
 345         unsigned i;
 346
 347         dma_resv_assert_held(dst);
 348
 349         rcu_read_lock();
 350         src_list = rcu_dereference(src->fence);
 351
 352 retry:
 353         if (src_list) {
 354                 unsigned shared_count = src_list->shared_count;
 355
 356                 rcu_read_unlock();
 357
 358                 dst_list = dma_resv_list_alloc(shared_count);
 359                 if (!dst_list)
 360                         return -ENOMEM;
 361
 362                 rcu_read_lock();
 363                 src_list = rcu_dereference(src->fence);
 364                 if (!src_list || src_list->shared_count > shared_count) {
 365                         kfree(dst_list);
 366                         goto retry;
 367                 }
 368
 369                 dst_list->shared_count = 0;
 370                 for (i = 0; i < src_list->shared_count; ++i) {
 371                         struct dma_fence *fence;
 372
 373                         fence = rcu_dereference(src_list->shared[i]);
 374                         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
 375                                      &fence->flags))
 376                                 continue;
 377
 378                         if (!dma_fence_get_rcu(fence)) {
 379                                 dma_resv_list_free(dst_list);
 380                                 src_list = rcu_dereference(src->fence);
 381                                 goto retry;
 382                         }
 383
 384                         if (dma_fence_is_signaled(fence)) {
 385                                 dma_fence_put(fence);
 386                                 continue;
 387                         }
 388
 389                         rcu_assign_pointer(dst_list->shared[dst_list->shared_count++], fence);
 390                 }
 391         } else {
 392                 dst_list = NULL;
 393         }
 394
 395         new = dma_fence_get_rcu_safe(&src->fence_excl);
 396         rcu_read_unlock();
 397
 398         src_list = dma_resv_get_list(dst);
 399         old = dma_resv_get_excl(dst);
 400
 401         write_seqcount_begin(&dst->seq);
 402         /* write_seqcount_begin provides the necessary memory barrier */
 403         RCU_INIT_POINTER(dst->fence_excl, new);
 404         RCU_INIT_POINTER(dst->fence, dst_list);
 405         write_seqcount_end(&dst->seq);
 406
 407         dma_resv_list_free(src_list);
 408         dma_fence_put(old);
 409
 410         return 0;
 411 }
 412 EXPORT_SYMBOL(dma_resv_copy_fences);
 413
 414 /**
 415  * dma_resv_get_fences_rcu - Get an object's shared and exclusive
 416  * fences without update side lock held
 417  * @obj: the reservation object
 418  * @pfence_excl: the returned exclusive fence (or NULL)
 419  * @pshared_count: the number of shared fences returned
 420  * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
 421  * the required size, and must be freed by caller)
 422  *
 423  * Retrieve all fences from the reservation object. If the pointer for the
 424  * exclusive fence is not specified the fence is put into the array of the
 425  * shared fences as well. Returns either zero or -ENOMEM.
 426  */
 427 int dma_resv_get_fences_rcu(struct dma_resv *obj,
 428                             struct dma_fence **pfence_excl,
 429                             unsigned *pshared_count,
 430                             struct dma_fence ***pshared)
 431 {
 432         struct dma_fence **shared = NULL;
 433         struct dma_fence *fence_excl;
 434         unsigned int shared_count;
 435         int ret = 1;
 436
 437         do {
 438                 struct dma_resv_list *fobj;
 439                 unsigned int i, seq;
 440                 size_t sz = 0;
 441
 442                 shared_count = i = 0;
 443
 444                 rcu_read_lock();
 445                 seq = read_seqcount_begin(&obj->seq);
 446
 447                 fence_excl = rcu_dereference(obj->fence_excl);
 448                 if (fence_excl && !dma_fence_get_rcu(fence_excl))
 449                         goto unlock;
 450
 451                 fobj = rcu_dereference(obj->fence);
 452                 if (fobj)
 453                         sz += sizeof(*shared) * fobj->shared_max;
 454
 455                 if (!pfence_excl && fence_excl)
 456                         sz += sizeof(*shared);
 457
 458                 if (sz) {
 459                         struct dma_fence **nshared;
 460
 461                         nshared = krealloc(shared, sz,
 462                                            GFP_NOWAIT | __GFP_NOWARN);
 463                         if (!nshared) {
 464                                 rcu_read_unlock();
 465
 466                                 dma_fence_put(fence_excl);
 467                                 fence_excl = NULL;
 468
 469                                 nshared = krealloc(shared, sz, GFP_KERNEL);
 470                                 if (nshared) {
 471                                         shared = nshared;
 472                                         continue;
 473                                 }
 474
 475                                 ret = -ENOMEM;
 476                                 break;
 477                         }
 478                         shared = nshared;
 479                         shared_count = fobj ? fobj->shared_count : 0;
 480                         for (i = 0; i < shared_count; ++i) {
 481                                 shared[i] = rcu_dereference(fobj->shared[i]);
 482                                 if (!dma_fence_get_rcu(shared[i]))
 483                                         break;
 484                         }
 485                 }
 486
 487                 if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
 488                         while (i--)
 489                                 dma_fence_put(shared[i]);
 490                         dma_fence_put(fence_excl);
 491                         goto unlock;
 492                 }
 493
 494                 ret = 0;
 495 unlock:
 496                 rcu_read_unlock();
 497         } while (ret);
 498
 499         if (pfence_excl)
 500                 *pfence_excl = fence_excl;
 501         else if (fence_excl)
 502                 shared[shared_count++] = fence_excl;
 503
 504         if (!shared_count) {
 505                 kfree(shared);
 506                 shared = NULL;
 507         }
 508
 509         *pshared_count = shared_count;
 510         *pshared = shared;
 511         return ret;
 512 }
 513 EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu);
 514
 515 /**
 516  * dma_resv_wait_timeout_rcu - Wait on reservation's objects
 517  * shared and/or exclusive fences.
 518  * @obj: the reservation object
 519  * @wait_all: if true, wait on all fences, else wait on just exclusive fence
 520  * @intr: if true, do interruptible wait
 521  * @timeout: timeout value in jiffies or zero to return immediately
 522  *
 523  * RETURNS
 524  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
 525  * greater than zer on success.
 526  */
 527 long dma_resv_wait_timeout_rcu(struct dma_resv *obj,
 528                                bool wait_all, bool intr,
 529                                unsigned long timeout)
 530 {
 531         struct dma_fence *fence;
 532         unsigned seq, shared_count;
 533         long ret = timeout ? timeout : 1;
 534         int i;
 535
 536 retry:
 537         shared_count = 0;
 538         seq = read_seqcount_begin(&obj->seq);
 539         rcu_read_lock();
 540         i = -1;
 541
 542         fence = rcu_dereference(obj->fence_excl);
 543         if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 544                 if (!dma_fence_get_rcu(fence))
 545                         goto unlock_retry;
 546
 547                 if (dma_fence_is_signaled(fence)) {
 548                         dma_fence_put(fence);
 549                         fence = NULL;
 550                 }
 551
 552         } else {
 553                 fence = NULL;
 554         }
 555
 556         if (wait_all) {
 557                 struct dma_resv_list *fobj = rcu_dereference(obj->fence);
 558
 559                 if (fobj)
 560                         shared_count = fobj->shared_count;
 561
 562                 for (i = 0; !fence && i < shared_count; ++i) {
 563                         struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
 564
 565                         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
 566                                      &lfence->flags))
 567                                 continue;
 568
 569                         if (!dma_fence_get_rcu(lfence))
 570                                 goto unlock_retry;
 571
 572                         if (dma_fence_is_signaled(lfence)) {
 573                                 dma_fence_put(lfence);
 574                                 continue;
 575                         }
 576
 577                         fence = lfence;
 578                         break;
 579                 }
 580         }
 581
 582         rcu_read_unlock();
 583         if (fence) {
 584                 if (read_seqcount_retry(&obj->seq, seq)) {
 585                         dma_fence_put(fence);
 586                         goto retry;
 587                 }
 588
 589                 ret = dma_fence_wait_timeout(fence, intr, ret);
 590                 dma_fence_put(fence);
 591                 if (ret > 0 && wait_all && (i + 1 < shared_count))
 592                         goto retry;
 593         }
 594         return ret;
 595
 596 unlock_retry:
 597         rcu_read_unlock();
 598         goto retry;
 599 }
 600 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout_rcu);
 601
 602
 603 static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
 604 {
 605         struct dma_fence *fence, *lfence = passed_fence;
 606         int ret = 1;
 607
 608         if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
 609                 fence = dma_fence_get_rcu(lfence);
 610                 if (!fence)
 611                         return -1;
 612
 613                 ret = !!dma_fence_is_signaled(fence);
 614                 dma_fence_put(fence);
 615         }
 616         return ret;
 617 }
 618
 619 /**
 620  * dma_resv_test_signaled_rcu - Test if a reservation object's
 621  * fences have been signaled.
 622  * @obj: the reservation object
 623  * @test_all: if true, test all fences, otherwise only test the exclusive
 624  * fence
 625  *
 626  * RETURNS
 627  * true if all fences signaled, else false
 628  */
 629 bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all)
 630 {
 631         unsigned seq, shared_count;
 632         int ret;
 633
 634         rcu_read_lock();
 635 retry:
 636         ret = true;
 637         shared_count = 0;
 638         seq = read_seqcount_begin(&obj->seq);
 639
 640         if (test_all) {
 641                 unsigned i;
 642
 643                 struct dma_resv_list *fobj = rcu_dereference(obj->fence);
 644
 645                 if (fobj)
 646                         shared_count = fobj->shared_count;
 647
 648                 for (i = 0; i < shared_count; ++i) {
 649                         struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
 650
 651                         ret = dma_resv_test_signaled_single(fence);
 652                         if (ret < 0)
 653                                 goto retry;
 654                         else if (!ret)
 655                                 break;
 656                 }
 657
 658                 if (read_seqcount_retry(&obj->seq, seq))
 659                         goto retry;
 660         }
 661
 662         if (!shared_count) {
 663                 struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl);
 664
 665                 if (fence_excl) {
 666                         ret = dma_resv_test_signaled_single(fence_excl);
 667                         if (ret < 0)
 668                                 goto retry;
 669
 670                         if (read_seqcount_retry(&obj->seq, seq))
 671                                 goto retry;
 672                 }
 673         }
 674
 675         rcu_read_unlock();
 676         return ret;
 677 }
 678 EXPORT_SYMBOL_GPL(dma_resv_test_signaled_rcu);