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 struct lock_class_key reservation_seqcount_class;
  56 EXPORT_SYMBOL(reservation_seqcount_class);
  57
  58 const char reservation_seqcount_string[] = "reservation_seqcount";
  59 EXPORT_SYMBOL(reservation_seqcount_string);
  60
  61 /**
  62  * dma_resv_list_alloc - allocate fence list
  63  * @shared_max: number of fences we need space for
  64  *
  65  * Allocate a new dma_resv_list and make sure to correctly initialize
  66  * shared_max.
  67  */
  68 static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
  69 {
  70         struct dma_resv_list *list;
  71
  72         list = kmalloc(offsetof(typeof(*list), shared[shared_max]), GFP_KERNEL);
  73         if (!list)
  74                 return NULL;
  75
  76         list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
  77                 sizeof(*list->shared);
  78
  79         return list;
  80 }
  81
  82 /**
  83  * dma_resv_list_free - free fence list
  84  * @list: list to free
  85  *
  86  * Free a dma_resv_list and make sure to drop all references.
  87  */
  88 static void dma_resv_list_free(struct dma_resv_list *list)
  89 {
  90         unsigned int i;
  91
  92         if (!list)
  93                 return;
  94
  95         for (i = 0; i < list->shared_count; ++i)
  96                 dma_fence_put(rcu_dereference_protected(list->shared[i], true));
  97
  98         kfree_rcu(list, rcu);
  99 }
 100
 101 #if IS_ENABLED(CONFIG_LOCKDEP)
 102 static int __init dma_resv_lockdep(void)
 103 {
 104         struct mm_struct *mm = mm_alloc();
 105         struct ww_acquire_ctx ctx;
 106         struct dma_resv obj;
 107         int ret;
 108
 109         if (!mm)
 110                 return -ENOMEM;
 111
 112         dma_resv_init(&obj);
 113
 114         mmap_read_lock(mm);
 115         ww_acquire_init(&ctx, &reservation_ww_class);
 116         ret = dma_resv_lock(&obj, &ctx);
 117         if (ret == -EDEADLK)
 118                 dma_resv_lock_slow(&obj, &ctx);
 119         fs_reclaim_acquire(GFP_KERNEL);
 120 #ifdef CONFIG_MMU_NOTIFIER
 121         lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
 122         __dma_fence_might_wait();
 123         lock_map_release(&__mmu_notifier_invalidate_range_start_map);
 124 #else
 125         __dma_fence_might_wait();
 126 #endif
 127         fs_reclaim_release(GFP_KERNEL);
 128         ww_mutex_unlock(&obj.lock);
 129         ww_acquire_fini(&ctx);
 130         mmap_read_unlock(mm);
 131
 132         mmput(mm);
 133
 134         return 0;
 135 }
 136 subsys_initcall(dma_resv_lockdep);
 137 #endif
 138
 139 /**
 140  * dma_resv_init - initialize a reservation object
 141  * @obj: the reservation object
 142  */
 143 void dma_resv_init(struct dma_resv *obj)
 144 {
 145         ww_mutex_init(&obj->lock, &reservation_ww_class);
 146
 147         __seqcount_init(&obj->seq, reservation_seqcount_string,
 148                         &reservation_seqcount_class);
 149         RCU_INIT_POINTER(obj->fence, NULL);
 150         RCU_INIT_POINTER(obj->fence_excl, NULL);
 151 }
 152 EXPORT_SYMBOL(dma_resv_init);
 153
 154 /**
 155  * dma_resv_fini - destroys a reservation object
 156  * @obj: the reservation object
 157  */
 158 void dma_resv_fini(struct dma_resv *obj)
 159 {
 160         struct dma_resv_list *fobj;
 161         struct dma_fence *excl;
 162
 163         /*
 164          * This object should be dead and all references must have
 165          * been released to it, so no need to be protected with rcu.
 166          */
 167         excl = rcu_dereference_protected(obj->fence_excl, 1);
 168         if (excl)
 169                 dma_fence_put(excl);
 170
 171         fobj = rcu_dereference_protected(obj->fence, 1);
 172         dma_resv_list_free(fobj);
 173         ww_mutex_destroy(&obj->lock);
 174 }
 175 EXPORT_SYMBOL(dma_resv_fini);
 176
 177 /**
 178  * dma_resv_reserve_shared - Reserve space to add shared fences to
 179  * a dma_resv.
 180  * @obj: reservation object
 181  * @num_fences: number of fences we want to add
 182  *
 183  * Should be called before dma_resv_add_shared_fence().  Must
 184  * be called with obj->lock held.
 185  *
 186  * RETURNS
 187  * Zero for success, or -errno
 188  */
 189 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
 190 {
 191         struct dma_resv_list *old, *new;
 192         unsigned int i, j, k, max;
 193
 194         dma_resv_assert_held(obj);
 195
 196         old = dma_resv_get_list(obj);
 197
 198         if (old && old->shared_max) {
 199                 if ((old->shared_count + num_fences) <= old->shared_max)
 200                         return 0;
 201                 else
 202                         max = max(old->shared_count + num_fences,
 203                                   old->shared_max * 2);
 204         } else {
 205                 max = 4;
 206         }
 207
 208         new = dma_resv_list_alloc(max);
 209         if (!new)
 210                 return -ENOMEM;
 211
 212         /*
 213          * no need to bump fence refcounts, rcu_read access
 214          * requires the use of kref_get_unless_zero, and the
 215          * references from the old struct are carried over to
 216          * the new.
 217          */
 218         for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
 219                 struct dma_fence *fence;
 220
 221                 fence = rcu_dereference_protected(old->shared[i],
 222                                                   dma_resv_held(obj));
 223                 if (dma_fence_is_signaled(fence))
 224                         RCU_INIT_POINTER(new->shared[--k], fence);
 225                 else
 226                         RCU_INIT_POINTER(new->shared[j++], fence);
 227         }
 228         new->shared_count = j;
 229
 230         /*
 231          * We are not changing the effective set of fences here so can
 232          * merely update the pointer to the new array; both existing
 233          * readers and new readers will see exactly the same set of
 234          * active (unsignaled) shared fences. Individual fences and the
 235          * old array are protected by RCU and so will not vanish under
 236          * the gaze of the rcu_read_lock() readers.
 237          */
 238         rcu_assign_pointer(obj->fence, new);
 239
 240         if (!old)
 241                 return 0;
 242
 243         /* Drop the references to the signaled fences */
 244         for (i = k; i < max; ++i) {
 245                 struct dma_fence *fence;
 246
 247                 fence = rcu_dereference_protected(new->shared[i],
 248                                                   dma_resv_held(obj));
 249                 dma_fence_put(fence);
 250         }
 251         kfree_rcu(old, rcu);
 252
 253         return 0;
 254 }
 255 EXPORT_SYMBOL(dma_resv_reserve_shared);
 256
 257 /**
 258  * dma_resv_add_shared_fence - Add a fence to a shared slot
 259  * @obj: the reservation object
 260  * @fence: the shared fence to add
 261  *
 262  * Add a fence to a shared slot, obj->lock must be held, and
 263  * dma_resv_reserve_shared() has been called.
 264  */
 265 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
 266 {
 267         struct dma_resv_list *fobj;
 268         struct dma_fence *old;
 269         unsigned int i, count;
 270
 271         dma_fence_get(fence);
 272
 273         dma_resv_assert_held(obj);
 274
 275         fobj = dma_resv_get_list(obj);
 276         count = fobj->shared_count;
 277
 278         preempt_disable();
 279         write_seqcount_begin(&obj->seq);
 280
 281         for (i = 0; i < count; ++i) {
 282
 283                 old = rcu_dereference_protected(fobj->shared[i],
 284                                                 dma_resv_held(obj));
 285                 if (old->context == fence->context ||
 286                     dma_fence_is_signaled(old))
 287                         goto replace;
 288         }
 289
 290         BUG_ON(fobj->shared_count >= fobj->shared_max);
 291         old = NULL;
 292         count++;
 293
 294 replace:
 295         RCU_INIT_POINTER(fobj->shared[i], fence);
 296         /* pointer update must be visible before we extend the shared_count */
 297         smp_store_mb(fobj->shared_count, count);
 298
 299         write_seqcount_end(&obj->seq);
 300         preempt_enable();
 301         dma_fence_put(old);
 302 }
 303 EXPORT_SYMBOL(dma_resv_add_shared_fence);
 304
 305 /**
 306  * dma_resv_add_excl_fence - Add an exclusive fence.
 307  * @obj: the reservation object
 308  * @fence: the shared fence to add
 309  *
 310  * Add a fence to the exclusive slot.  The obj->lock must be held.
 311  */
 312 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 313 {
 314         struct dma_fence *old_fence = dma_resv_get_excl(obj);
 315         struct dma_resv_list *old;
 316         u32 i = 0;
 317
 318         dma_resv_assert_held(obj);
 319
 320         old = dma_resv_get_list(obj);
 321         if (old)
 322                 i = old->shared_count;
 323
 324         if (fence)
 325                 dma_fence_get(fence);
 326
 327         preempt_disable();
 328         write_seqcount_begin(&obj->seq);
 329         /* write_seqcount_begin provides the necessary memory barrier */
 330         RCU_INIT_POINTER(obj->fence_excl, fence);
 331         if (old)
 332                 old->shared_count = 0;
 333         write_seqcount_end(&obj->seq);
 334         preempt_enable();
 335
 336         /* inplace update, no shared fences */
 337         while (i--)
 338                 dma_fence_put(rcu_dereference_protected(old->shared[i],
 339                                                 dma_resv_held(obj)));
 340
 341         dma_fence_put(old_fence);
 342 }
 343 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 344
 345 /**
 346 * dma_resv_copy_fences - Copy all fences from src to dst.
 347 * @dst: the destination reservation object
 348 * @src: the source reservation object
 349 *
 350 * Copy all fences from src to dst. dst-lock must be held.
 351 */
 352 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 353 {
 354         struct dma_resv_list *src_list, *dst_list;
 355         struct dma_fence *old, *new;
 356         unsigned i;
 357
 358         dma_resv_assert_held(dst);
 359
 360         rcu_read_lock();
 361         src_list = rcu_dereference(src->fence);
 362
 363 retry:
 364         if (src_list) {
 365                 unsigned shared_count = src_list->shared_count;
 366
 367                 rcu_read_unlock();
 368
 369                 dst_list = dma_resv_list_alloc(shared_count);
 370                 if (!dst_list)
 371                         return -ENOMEM;
 372
 373                 rcu_read_lock();
 374                 src_list = rcu_dereference(src->fence);
 375                 if (!src_list || src_list->shared_count > shared_count) {
 376                         kfree(dst_list);
 377                         goto retry;
 378                 }
 379
 380                 dst_list->shared_count = 0;
 381                 for (i = 0; i < src_list->shared_count; ++i) {
 382                         struct dma_fence *fence;
 383
 384                         fence = rcu_dereference(src_list->shared[i]);
 385                         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
 386                                      &fence->flags))
 387                                 continue;
 388
 389                         if (!dma_fence_get_rcu(fence)) {
 390                                 dma_resv_list_free(dst_list);
 391                                 src_list = rcu_dereference(src->fence);
 392                                 goto retry;
 393                         }
 394
 395                         if (dma_fence_is_signaled(fence)) {
 396                                 dma_fence_put(fence);
 397                                 continue;
 398                         }
 399
 400                         rcu_assign_pointer(dst_list->shared[dst_list->shared_count++], fence);
 401                 }
 402         } else {
 403                 dst_list = NULL;
 404         }
 405
 406         new = dma_fence_get_rcu_safe(&src->fence_excl);
 407         rcu_read_unlock();
 408
 409         src_list = dma_resv_get_list(dst);
 410         old = dma_resv_get_excl(dst);
 411
 412         preempt_disable();
 413         write_seqcount_begin(&dst->seq);
 414         /* write_seqcount_begin provides the necessary memory barrier */
 415         RCU_INIT_POINTER(dst->fence_excl, new);
 416         RCU_INIT_POINTER(dst->fence, dst_list);
 417         write_seqcount_end(&dst->seq);
 418         preempt_enable();
 419
 420         dma_resv_list_free(src_list);
 421         dma_fence_put(old);
 422
 423         return 0;
 424 }
 425 EXPORT_SYMBOL(dma_resv_copy_fences);
 426
 427 /**
 428  * dma_resv_get_fences_rcu - Get an object's shared and exclusive
 429  * fences without update side lock held
 430  * @obj: the reservation object
 431  * @pfence_excl: the returned exclusive fence (or NULL)
 432  * @pshared_count: the number of shared fences returned
 433  * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
 434  * the required size, and must be freed by caller)
 435  *
 436  * Retrieve all fences from the reservation object. If the pointer for the
 437  * exclusive fence is not specified the fence is put into the array of the
 438  * shared fences as well. Returns either zero or -ENOMEM.
 439  */
 440 int dma_resv_get_fences_rcu(struct dma_resv *obj,
 441                             struct dma_fence **pfence_excl,
 442                             unsigned *pshared_count,
 443                             struct dma_fence ***pshared)
 444 {
 445         struct dma_fence **shared = NULL;
 446         struct dma_fence *fence_excl;
 447         unsigned int shared_count;
 448         int ret = 1;
 449
 450         do {
 451                 struct dma_resv_list *fobj;
 452                 unsigned int i, seq;
 453                 size_t sz = 0;
 454
 455                 shared_count = i = 0;
 456
 457                 rcu_read_lock();
 458                 seq = read_seqcount_begin(&obj->seq);
 459
 460                 fence_excl = rcu_dereference(obj->fence_excl);
 461                 if (fence_excl && !dma_fence_get_rcu(fence_excl))
 462                         goto unlock;
 463
 464                 fobj = rcu_dereference(obj->fence);
 465                 if (fobj)
 466                         sz += sizeof(*shared) * fobj->shared_max;
 467
 468                 if (!pfence_excl && fence_excl)
 469                         sz += sizeof(*shared);
 470
 471                 if (sz) {
 472                         struct dma_fence **nshared;
 473
 474                         nshared = krealloc(shared, sz,
 475                                            GFP_NOWAIT | __GFP_NOWARN);
 476                         if (!nshared) {
 477                                 rcu_read_unlock();
 478
 479                                 dma_fence_put(fence_excl);
 480                                 fence_excl = NULL;
 481
 482                                 nshared = krealloc(shared, sz, GFP_KERNEL);
 483                                 if (nshared) {
 484                                         shared = nshared;
 485                                         continue;
 486                                 }
 487
 488                                 ret = -ENOMEM;
 489                                 break;
 490                         }
 491                         shared = nshared;
 492                         shared_count = fobj ? fobj->shared_count : 0;
 493                         for (i = 0; i < shared_count; ++i) {
 494                                 shared[i] = rcu_dereference(fobj->shared[i]);
 495                                 if (!dma_fence_get_rcu(shared[i]))
 496                                         break;
 497                         }
 498                 }
 499
 500                 if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
 501                         while (i--)
 502                                 dma_fence_put(shared[i]);
 503                         dma_fence_put(fence_excl);
 504                         goto unlock;
 505                 }
 506
 507                 ret = 0;
 508 unlock:
 509                 rcu_read_unlock();
 510         } while (ret);
 511
 512         if (pfence_excl)
 513                 *pfence_excl = fence_excl;
 514         else if (fence_excl)
 515                 shared[shared_count++] = fence_excl;
 516
 517         if (!shared_count) {
 518                 kfree(shared);
 519                 shared = NULL;
 520         }
 521
 522         *pshared_count = shared_count;
 523         *pshared = shared;
 524         return ret;
 525 }
 526 EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu);
 527
 528 /**
 529  * dma_resv_wait_timeout_rcu - Wait on reservation's objects
 530  * shared and/or exclusive fences.
 531  * @obj: the reservation object
 532  * @wait_all: if true, wait on all fences, else wait on just exclusive fence
 533  * @intr: if true, do interruptible wait
 534  * @timeout: timeout value in jiffies or zero to return immediately
 535  *
 536  * RETURNS
 537  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
 538  * greater than zer on success.
 539  */
 540 long dma_resv_wait_timeout_rcu(struct dma_resv *obj,
 541                                bool wait_all, bool intr,
 542                                unsigned long timeout)
 543 {
 544         struct dma_fence *fence;
 545         unsigned seq, shared_count;
 546         long ret = timeout ? timeout : 1;
 547         int i;
 548
 549 retry:
 550         shared_count = 0;
 551         seq = read_seqcount_begin(&obj->seq);
 552         rcu_read_lock();
 553         i = -1;
 554
 555         fence = rcu_dereference(obj->fence_excl);
 556         if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 557                 if (!dma_fence_get_rcu(fence))
 558                         goto unlock_retry;
 559
 560                 if (dma_fence_is_signaled(fence)) {
 561                         dma_fence_put(fence);
 562                         fence = NULL;
 563                 }
 564
 565         } else {
 566                 fence = NULL;
 567         }
 568
 569         if (wait_all) {
 570                 struct dma_resv_list *fobj = rcu_dereference(obj->fence);
 571
 572                 if (fobj)
 573                         shared_count = fobj->shared_count;
 574
 575                 for (i = 0; !fence && i < shared_count; ++i) {
 576                         struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
 577
 578                         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
 579                                      &lfence->flags))
 580                                 continue;
 581
 582                         if (!dma_fence_get_rcu(lfence))
 583                                 goto unlock_retry;
 584
 585                         if (dma_fence_is_signaled(lfence)) {
 586                                 dma_fence_put(lfence);
 587                                 continue;
 588                         }
 589
 590                         fence = lfence;
 591                         break;
 592                 }
 593         }
 594
 595         rcu_read_unlock();
 596         if (fence) {
 597                 if (read_seqcount_retry(&obj->seq, seq)) {
 598                         dma_fence_put(fence);
 599                         goto retry;
 600                 }
 601
 602                 ret = dma_fence_wait_timeout(fence, intr, ret);
 603                 dma_fence_put(fence);
 604                 if (ret > 0 && wait_all && (i + 1 < shared_count))
 605                         goto retry;
 606         }
 607         return ret;
 608
 609 unlock_retry:
 610         rcu_read_unlock();
 611         goto retry;
 612 }
 613 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout_rcu);
 614
 615
 616 static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
 617 {
 618         struct dma_fence *fence, *lfence = passed_fence;
 619         int ret = 1;
 620
 621         if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
 622                 fence = dma_fence_get_rcu(lfence);
 623                 if (!fence)
 624                         return -1;
 625
 626                 ret = !!dma_fence_is_signaled(fence);
 627                 dma_fence_put(fence);
 628         }
 629         return ret;
 630 }
 631
 632 /**
 633  * dma_resv_test_signaled_rcu - Test if a reservation object's
 634  * fences have been signaled.
 635  * @obj: the reservation object
 636  * @test_all: if true, test all fences, otherwise only test the exclusive
 637  * fence
 638  *
 639  * RETURNS
 640  * true if all fences signaled, else false
 641  */
 642 bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all)
 643 {
 644         unsigned seq, shared_count;
 645         int ret;
 646
 647         rcu_read_lock();
 648 retry:
 649         ret = true;
 650         shared_count = 0;
 651         seq = read_seqcount_begin(&obj->seq);
 652
 653         if (test_all) {
 654                 unsigned i;
 655
 656                 struct dma_resv_list *fobj = rcu_dereference(obj->fence);
 657
 658                 if (fobj)
 659                         shared_count = fobj->shared_count;
 660
 661                 for (i = 0; i < shared_count; ++i) {
 662                         struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
 663
 664                         ret = dma_resv_test_signaled_single(fence);
 665                         if (ret < 0)
 666                                 goto retry;
 667                         else if (!ret)
 668                                 break;
 669                 }
 670
 671                 if (read_seqcount_retry(&obj->seq, seq))
 672                         goto retry;
 673         }
 674
 675         if (!shared_count) {
 676                 struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl);
 677
 678                 if (fence_excl) {
 679                         ret = dma_resv_test_signaled_single(fence_excl);
 680                         if (ret < 0)
 681                                 goto retry;
 682
 683                         if (read_seqcount_retry(&obj->seq, seq))
 684                                 goto retry;
 685                 }
 686         }
 687
 688         rcu_read_unlock();
 689         return ret;
 690 }
 691 EXPORT_SYMBOL_GPL(dma_resv_test_signaled_rcu);