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
  38 /**
  39  * DOC: Reservation Object Overview
  40  *
  41  * The reservation object provides a mechanism to manage shared and
  42  * exclusive fences associated with a buffer.  A reservation object
  43  * can have attached one exclusive fence (normally associated with
  44  * write operations) or N shared fences (read operations).  The RCU
  45  * mechanism is used to protect read access to fences from locked
  46  * write-side updates.
  47  */
  48
  49 DEFINE_WD_CLASS(reservation_ww_class);
  50 EXPORT_SYMBOL(reservation_ww_class);
  51
  52 /**
  53  * dma_resv_list_alloc - allocate fence list
  54  * @shared_max: number of fences we need space for
  55  *
  56  * Allocate a new dma_resv_list and make sure to correctly initialize
  57  * shared_max.
  58  */
  59 static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
  60 {
  61         struct dma_resv_list *list;
  62
  63         list = kmalloc(offsetof(typeof(*list), shared[shared_max]), GFP_KERNEL);
  64         if (!list)
  65                 return NULL;
  66
  67         list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
  68                 sizeof(*list->shared);
  69
  70         return list;
  71 }
  72
  73 /**
  74  * dma_resv_list_free - free fence list
  75  * @list: list to free
  76  *
  77  * Free a dma_resv_list and make sure to drop all references.
  78  */
  79 static void dma_resv_list_free(struct dma_resv_list *list)
  80 {
  81         unsigned int i;
  82
  83         if (!list)
  84                 return;
  85
  86         for (i = 0; i < list->shared_count; ++i)
  87                 dma_fence_put(rcu_dereference_protected(list->shared[i], true));
  88
  89         kfree_rcu(list, rcu);
  90 }
  91
  92 /**
  93  * dma_resv_init - initialize a reservation object
  94  * @obj: the reservation object
  95  */
  96 void dma_resv_init(struct dma_resv *obj)
  97 {
  98         ww_mutex_init(&obj->lock, &reservation_ww_class);
  99         RCU_INIT_POINTER(obj->fence, NULL);
 100         RCU_INIT_POINTER(obj->fence_excl, NULL);
 101 }
 102 EXPORT_SYMBOL(dma_resv_init);
 103
 104 /**
 105  * dma_resv_fini - destroys a reservation object
 106  * @obj: the reservation object
 107  */
 108 void dma_resv_fini(struct dma_resv *obj)
 109 {
 110         struct dma_resv_list *fobj;
 111         struct dma_fence *excl;
 112
 113         /*
 114          * This object should be dead and all references must have
 115          * been released to it, so no need to be protected with rcu.
 116          */
 117         excl = rcu_dereference_protected(obj->fence_excl, 1);
 118         if (excl)
 119                 dma_fence_put(excl);
 120
 121         fobj = rcu_dereference_protected(obj->fence, 1);
 122         dma_resv_list_free(fobj);
 123         ww_mutex_destroy(&obj->lock);
 124 }
 125 EXPORT_SYMBOL(dma_resv_fini);
 126
 127 /**
 128  * dma_resv_reserve_shared - Reserve space to add shared fences to
 129  * a dma_resv.
 130  * @obj: reservation object
 131  * @num_fences: number of fences we want to add
 132  *
 133  * Should be called before dma_resv_add_shared_fence().  Must
 134  * be called with obj->lock held.
 135  *
 136  * RETURNS
 137  * Zero for success, or -errno
 138  */
 139 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
 140 {
 141         struct dma_resv_list *old, *new;
 142         unsigned int i, j, k, max;
 143
 144         dma_resv_assert_held(obj);
 145
 146         old = dma_resv_get_list(obj);
 147
 148         if (old && old->shared_max) {
 149                 if ((old->shared_count + num_fences) <= old->shared_max)
 150                         return 0;
 151                 else
 152                         max = max(old->shared_count + num_fences,
 153                                   old->shared_max * 2);
 154         } else {
 155                 max = 4;
 156         }
 157
 158         new = dma_resv_list_alloc(max);
 159         if (!new)
 160                 return -ENOMEM;
 161
 162         /*
 163          * no need to bump fence refcounts, rcu_read access
 164          * requires the use of kref_get_unless_zero, and the
 165          * references from the old struct are carried over to
 166          * the new.
 167          */
 168         for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
 169                 struct dma_fence *fence;
 170
 171                 fence = rcu_dereference_protected(old->shared[i],
 172                                                   dma_resv_held(obj));
 173                 if (dma_fence_is_signaled(fence))
 174                         RCU_INIT_POINTER(new->shared[--k], fence);
 175                 else
 176                         RCU_INIT_POINTER(new->shared[j++], fence);
 177         }
 178         new->shared_count = j;
 179
 180         /*
 181          * We are not changing the effective set of fences here so can
 182          * merely update the pointer to the new array; both existing
 183          * readers and new readers will see exactly the same set of
 184          * active (unsignaled) shared fences. Individual fences and the
 185          * old array are protected by RCU and so will not vanish under
 186          * the gaze of the rcu_read_lock() readers.
 187          */
 188         rcu_assign_pointer(obj->fence, new);
 189
 190         if (!old)
 191                 return 0;
 192
 193         /* Drop the references to the signaled fences */
 194         for (i = k; i < max; ++i) {
 195                 struct dma_fence *fence;
 196
 197                 fence = rcu_dereference_protected(new->shared[i],
 198                                                   dma_resv_held(obj));
 199                 dma_fence_put(fence);
 200         }
 201         kfree_rcu(old, rcu);
 202
 203         return 0;
 204 }
 205 EXPORT_SYMBOL(dma_resv_reserve_shared);
 206
 207 /**
 208  * dma_resv_add_shared_fence - Add a fence to a shared slot
 209  * @obj: the reservation object
 210  * @fence: the shared fence to add
 211  *
 212  * Add a fence to a shared slot, obj->lock must be held, and
 213  * dma_resv_reserve_shared() has been called.
 214  */
 215 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
 216 {
 217         struct dma_resv_list *fobj;
 218         struct dma_fence *old;
 219         unsigned int i, count;
 220
 221         dma_fence_get(fence);
 222
 223         dma_resv_assert_held(obj);
 224
 225         fobj = dma_resv_get_list(obj);
 226         count = fobj->shared_count;
 227
 228         for (i = 0; i < count; ++i) {
 229
 230                 old = rcu_dereference_protected(fobj->shared[i],
 231                                                 dma_resv_held(obj));
 232                 if (old->context == fence->context ||
 233                     dma_fence_is_signaled(old))
 234                         goto replace;
 235         }
 236
 237         BUG_ON(fobj->shared_count >= fobj->shared_max);
 238         old = NULL;
 239         count++;
 240
 241 replace:
 242         RCU_INIT_POINTER(fobj->shared[i], fence);
 243         /* pointer update must be visible before we extend the shared_count */
 244         smp_store_mb(fobj->shared_count, count);
 245         dma_fence_put(old);
 246 }
 247 EXPORT_SYMBOL(dma_resv_add_shared_fence);
 248
 249 /**
 250  * dma_resv_add_excl_fence - Add an exclusive fence.
 251  * @obj: the reservation object
 252  * @fence: the shared fence to add
 253  *
 254  * Add a fence to the exclusive slot.  The obj->lock must be held.
 255  */
 256 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 257 {
 258         struct dma_fence *old_fence = dma_resv_get_excl(obj);
 259         struct dma_resv_list *old;
 260         u32 i = 0;
 261
 262         dma_resv_assert_held(obj);
 263
 264         old = dma_resv_get_list(obj);
 265         if (old)
 266                 i = old->shared_count;
 267
 268         if (fence)
 269                 dma_fence_get(fence);
 270
 271         preempt_disable();
 272         rcu_assign_pointer(obj->fence_excl, fence);
 273         /* pointer update must be visible before we modify the shared_count */
 274         if (old)
 275                 smp_store_mb(old->shared_count, 0);
 276         preempt_enable();
 277
 278         /* inplace update, no shared fences */
 279         while (i--)
 280                 dma_fence_put(rcu_dereference_protected(old->shared[i],
 281                                                 dma_resv_held(obj)));
 282
 283         dma_fence_put(old_fence);
 284 }
 285 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 286
 287 /**
 288 * dma_resv_copy_fences - Copy all fences from src to dst.
 289 * @dst: the destination reservation object
 290 * @src: the source reservation object
 291 *
 292 * Copy all fences from src to dst. dst-lock must be held.
 293 */
 294 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 295 {
 296         struct dma_resv_list *src_list, *dst_list;
 297         struct dma_fence *old, *new;
 298         unsigned int i, shared_count;
 299
 300         dma_resv_assert_held(dst);
 301
 302         rcu_read_lock();
 303
 304 retry:
 305         dma_resv_fences(src, &new, &src_list, &shared_count);
 306         if (shared_count) {
 307                 rcu_read_unlock();
 308
 309                 dst_list = dma_resv_list_alloc(shared_count);
 310                 if (!dst_list)
 311                         return -ENOMEM;
 312
 313                 rcu_read_lock();
 314                 dma_resv_fences(src, &new, &src_list, &shared_count);
 315                 if (!src_list || shared_count > dst_list->shared_max) {
 316                         kfree(dst_list);
 317                         goto retry;
 318                 }
 319
 320                 dst_list->shared_count = 0;
 321                 for (i = 0; i < shared_count; ++i) {
 322                         struct dma_fence *fence;
 323
 324                         fence = rcu_dereference(src_list->shared[i]);
 325                         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
 326                                      &fence->flags))
 327                                 continue;
 328
 329                         if (!dma_fence_get_rcu(fence)) {
 330                                 dma_resv_list_free(dst_list);
 331                                 goto retry;
 332                         }
 333
 334                         if (dma_fence_is_signaled(fence)) {
 335                                 dma_fence_put(fence);
 336                                 continue;
 337                         }
 338
 339                         rcu_assign_pointer(dst_list->shared[dst_list->shared_count++], fence);
 340                 }
 341         } else {
 342                 dst_list = NULL;
 343         }
 344
 345         if (new && !dma_fence_get_rcu(new)) {
 346                 dma_resv_list_free(dst_list);
 347                 goto retry;
 348         }
 349         rcu_read_unlock();
 350
 351         src_list = dma_resv_get_list(dst);
 352         old = dma_resv_get_excl(dst);
 353
 354         preempt_disable();
 355         rcu_assign_pointer(dst->fence_excl, new);
 356         rcu_assign_pointer(dst->fence, dst_list);
 357         preempt_enable();
 358
 359         dma_resv_list_free(src_list);
 360         dma_fence_put(old);
 361
 362         return 0;
 363 }
 364 EXPORT_SYMBOL(dma_resv_copy_fences);
 365
 366 /**
 367  * dma_resv_get_fences_rcu - Get an object's shared and exclusive
 368  * fences without update side lock held
 369  * @obj: the reservation object
 370  * @pfence_excl: the returned exclusive fence (or NULL)
 371  * @pshared_count: the number of shared fences returned
 372  * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
 373  * the required size, and must be freed by caller)
 374  *
 375  * Retrieve all fences from the reservation object. If the pointer for the
 376  * exclusive fence is not specified the fence is put into the array of the
 377  * shared fences as well. Returns either zero or -ENOMEM.
 378  */
 379 int dma_resv_get_fences_rcu(struct dma_resv *obj,
 380                             struct dma_fence **pfence_excl,
 381                             unsigned *pshared_count,
 382                             struct dma_fence ***pshared)
 383 {
 384         struct dma_fence **shared = NULL;
 385         struct dma_fence *fence_excl;
 386         unsigned int shared_count;
 387         int ret = 1;
 388
 389         do {
 390                 struct dma_resv_list *fobj;
 391                 unsigned int i;
 392                 size_t sz = 0;
 393
 394                 i = 0;
 395
 396                 rcu_read_lock();
 397                 dma_resv_fences(obj, &fence_excl, &fobj,
 398                                           &shared_count);
 399
 400                 if (fence_excl && !dma_fence_get_rcu(fence_excl))
 401                         goto unlock;
 402
 403                 if (fobj)
 404                         sz += sizeof(*shared) * fobj->shared_max;
 405
 406                 if (!pfence_excl && fence_excl)
 407                         sz += sizeof(*shared);
 408
 409                 if (sz) {
 410                         struct dma_fence **nshared;
 411
 412                         nshared = krealloc(shared, sz,
 413                                            GFP_NOWAIT | __GFP_NOWARN);
 414                         if (!nshared) {
 415                                 rcu_read_unlock();
 416
 417                                 dma_fence_put(fence_excl);
 418                                 fence_excl = NULL;
 419
 420                                 nshared = krealloc(shared, sz, GFP_KERNEL);
 421                                 if (nshared) {
 422                                         shared = nshared;
 423                                         continue;
 424                                 }
 425
 426                                 ret = -ENOMEM;
 427                                 break;
 428                         }
 429                         shared = nshared;
 430                         for (i = 0; i < shared_count; ++i) {
 431                                 shared[i] = rcu_dereference(fobj->shared[i]);
 432                                 if (!dma_fence_get_rcu(shared[i]))
 433                                         break;
 434                         }
 435                 }
 436
 437                 if (i != shared_count) {
 438                         while (i--)
 439                                 dma_fence_put(shared[i]);
 440                         dma_fence_put(fence_excl);
 441                         goto unlock;
 442                 }
 443
 444                 ret = 0;
 445 unlock:
 446                 rcu_read_unlock();
 447         } while (ret);
 448
 449         if (pfence_excl)
 450                 *pfence_excl = fence_excl;
 451         else if (fence_excl)
 452                 shared[++shared_count] = fence_excl;
 453
 454         if (!shared_count) {
 455                 kfree(shared);
 456                 shared = NULL;
 457         }
 458
 459         *pshared_count = shared_count;
 460         *pshared = shared;
 461         return ret;
 462 }
 463 EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu);
 464
 465 /**
 466  * dma_resv_wait_timeout_rcu - Wait on reservation's objects
 467  * shared and/or exclusive fences.
 468  * @obj: the reservation object
 469  * @wait_all: if true, wait on all fences, else wait on just exclusive fence
 470  * @intr: if true, do interruptible wait
 471  * @timeout: timeout value in jiffies or zero to return immediately
 472  *
 473  * RETURNS
 474  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
 475  * greater than zer on success.
 476  */
 477 long dma_resv_wait_timeout_rcu(struct dma_resv *obj,
 478                                bool wait_all, bool intr,
 479                                unsigned long timeout)
 480 {
 481         struct dma_resv_list *fobj;
 482         struct dma_fence *fence;
 483         unsigned shared_count;
 484         long ret = timeout ? timeout : 1;
 485         int i;
 486
 487 retry:
 488         rcu_read_lock();
 489         i = -1;
 490
 491         dma_resv_fences(obj, &fence, &fobj, &shared_count);
 492         if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
 493                 if (!dma_fence_get_rcu(fence))
 494                         goto unlock_retry;
 495
 496                 if (dma_fence_is_signaled(fence)) {
 497                         dma_fence_put(fence);
 498                         fence = NULL;
 499                 }
 500
 501         } else {
 502                 fence = NULL;
 503         }
 504
 505         if (wait_all) {
 506                 for (i = 0; !fence && i < shared_count; ++i) {
 507                         struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
 508
 509                         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
 510                                      &lfence->flags))
 511                                 continue;
 512
 513                         if (!dma_fence_get_rcu(lfence))
 514                                 goto unlock_retry;
 515
 516                         if (dma_fence_is_signaled(lfence)) {
 517                                 dma_fence_put(lfence);
 518                                 continue;
 519                         }
 520
 521                         fence = lfence;
 522                         break;
 523                 }
 524         }
 525
 526         rcu_read_unlock();
 527         if (fence) {
 528                 ret = dma_fence_wait_timeout(fence, intr, ret);
 529                 dma_fence_put(fence);
 530                 if (ret > 0 && wait_all && (i + 1 < shared_count))
 531                         goto retry;
 532         }
 533         return ret;
 534
 535 unlock_retry:
 536         rcu_read_unlock();
 537         goto retry;
 538 }
 539 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout_rcu);
 540
 541
 542 static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
 543 {
 544         struct dma_fence *fence, *lfence = passed_fence;
 545         int ret = 1;
 546
 547         if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
 548                 fence = dma_fence_get_rcu(lfence);
 549                 if (!fence)
 550                         return -1;
 551
 552                 ret = !!dma_fence_is_signaled(fence);
 553                 dma_fence_put(fence);
 554         }
 555         return ret;
 556 }
 557
 558 /**
 559  * dma_resv_test_signaled_rcu - Test if a reservation object's
 560  * fences have been signaled.
 561  * @obj: the reservation object
 562  * @test_all: if true, test all fences, otherwise only test the exclusive
 563  * fence
 564  *
 565  * RETURNS
 566  * true if all fences signaled, else false
 567  */
 568 bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all)
 569 {
 570         struct dma_resv_list *fobj;
 571         struct dma_fence *fence_excl;
 572         unsigned shared_count;
 573         int ret;
 574
 575         rcu_read_lock();
 576 retry:
 577         ret = true;
 578
 579         dma_resv_fences(obj, &fence_excl, &fobj, &shared_count);
 580         if (test_all) {
 581                 unsigned i;
 582
 583                 for (i = 0; i < shared_count; ++i) {
 584                         struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
 585
 586                         ret = dma_resv_test_signaled_single(fence);
 587                         if (ret < 0)
 588                                 goto retry;
 589                         else if (!ret)
 590                                 break;
 591                 }
 592         }
 593
 594         if (!shared_count && fence_excl) {
 595                 ret = dma_resv_test_signaled_single(fence_excl);
 596                 if (ret < 0)
 597                         goto retry;
 598         }
 599
 600         rcu_read_unlock();
 601         return ret;
 602 }
 603 EXPORT_SYMBOL_GPL(dma_resv_test_signaled_rcu);