drivers/gpu/drm/i915/i915_sw_fence.c

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * (C) Copyright 2016 Intel Corporation
   5  */
   6
   7 #include <linux/slab.h>
   8 #include <linux/dma-fence.h>
   9 #include <linux/irq_work.h>
  10 #include <linux/dma-resv.h>
  11
  12 #include "i915_sw_fence.h"
  13 #include "i915_selftest.h"
  14
  15 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
  16 #define I915_SW_FENCE_BUG_ON(expr) BUG_ON(expr)
  17 #else
  18 #define I915_SW_FENCE_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
  19 #endif
  20
  21 #define I915_SW_FENCE_FLAG_ALLOC BIT(3) /* after WQ_FLAG_* for safety */
  22
  23 static DEFINE_SPINLOCK(i915_sw_fence_lock);
  24
  25 enum {
  26         DEBUG_FENCE_IDLE = 0,
  27         DEBUG_FENCE_NOTIFY,
  28 };
  29
  30 static void *i915_sw_fence_debug_hint(void *addr)
  31 {
  32         return (void *)(((struct i915_sw_fence *)addr)->flags & I915_SW_FENCE_MASK);
  33 }
  34
  35 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
  36
  37 static const struct debug_obj_descr i915_sw_fence_debug_descr = {
  38         .name = "i915_sw_fence",
  39         .debug_hint = i915_sw_fence_debug_hint,
  40 };
  41
  42 static inline void debug_fence_init(struct i915_sw_fence *fence)
  43 {
  44         debug_object_init(fence, &i915_sw_fence_debug_descr);
  45 }
  46
  47 static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
  48 {
  49         debug_object_init_on_stack(fence, &i915_sw_fence_debug_descr);
  50 }
  51
  52 static inline void debug_fence_activate(struct i915_sw_fence *fence)
  53 {
  54         debug_object_activate(fence, &i915_sw_fence_debug_descr);
  55 }
  56
  57 static inline void debug_fence_set_state(struct i915_sw_fence *fence,
  58                                          int old, int new)
  59 {
  60         debug_object_active_state(fence, &i915_sw_fence_debug_descr, old, new);
  61 }
  62
  63 static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
  64 {
  65         debug_object_deactivate(fence, &i915_sw_fence_debug_descr);
  66 }
  67
  68 static inline void debug_fence_destroy(struct i915_sw_fence *fence)
  69 {
  70         debug_object_destroy(fence, &i915_sw_fence_debug_descr);
  71 }
  72
  73 static inline void debug_fence_free(struct i915_sw_fence *fence)
  74 {
  75         debug_object_free(fence, &i915_sw_fence_debug_descr);
  76         smp_wmb(); /* flush the change in state before reallocation */
  77 }
  78
  79 static inline void debug_fence_assert(struct i915_sw_fence *fence)
  80 {
  81         debug_object_assert_init(fence, &i915_sw_fence_debug_descr);
  82 }
  83
  84 #else
  85
  86 static inline void debug_fence_init(struct i915_sw_fence *fence)
  87 {
  88 }
  89
  90 static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
  91 {
  92 }
  93
  94 static inline void debug_fence_activate(struct i915_sw_fence *fence)
  95 {
  96 }
  97
  98 static inline void debug_fence_set_state(struct i915_sw_fence *fence,
  99                                          int old, int new)
 100 {
 101 }
 102
 103 static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
 104 {
 105 }
 106
 107 static inline void debug_fence_destroy(struct i915_sw_fence *fence)
 108 {
 109 }
 110
 111 static inline void debug_fence_free(struct i915_sw_fence *fence)
 112 {
 113 }
 114
 115 static inline void debug_fence_assert(struct i915_sw_fence *fence)
 116 {
 117 }
 118
 119 #endif
 120
 121 static int __i915_sw_fence_notify(struct i915_sw_fence *fence,
 122                                   enum i915_sw_fence_notify state)
 123 {
 124         i915_sw_fence_notify_t fn;
 125
 126         fn = (i915_sw_fence_notify_t)(fence->flags & I915_SW_FENCE_MASK);
 127         return fn(fence, state);
 128 }
 129
 130 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
 131 void i915_sw_fence_fini(struct i915_sw_fence *fence)
 132 {
 133         debug_fence_free(fence);
 134 }
 135 #endif
 136
 137 static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
 138                                         struct list_head *continuation)
 139 {
 140         wait_queue_head_t *x = &fence->wait;
 141         wait_queue_entry_t *pos, *next;
 142         unsigned long flags;
 143
 144         debug_fence_deactivate(fence);
 145         atomic_set_release(&fence->pending, -1); /* 0 -> -1 [done] */
 146
 147         /*
 148          * To prevent unbounded recursion as we traverse the graph of
 149          * i915_sw_fences, we move the entry list from this, the next ready
 150          * fence, to the tail of the original fence's entry list
 151          * (and so added to the list to be woken).
 152          */
 153
 154         spin_lock_irqsave_nested(&x->lock, flags, 1 + !!continuation);
 155         if (continuation) {
 156                 list_for_each_entry_safe(pos, next, &x->head, entry) {
 157                         if (pos->func == autoremove_wake_function)
 158                                 pos->func(pos, TASK_NORMAL, 0, continuation);
 159                         else
 160                                 list_move_tail(&pos->entry, continuation);
 161                 }
 162         } else {
 163                 LIST_HEAD(extra);
 164
 165                 do {
 166                         list_for_each_entry_safe(pos, next, &x->head, entry) {
 167                                 int wake_flags;
 168
 169                                 wake_flags = fence->error;
 170                                 if (pos->func == autoremove_wake_function)
 171                                         wake_flags = 0;
 172
 173                                 pos->func(pos, TASK_NORMAL, wake_flags, &extra);
 174                         }
 175
 176                         if (list_empty(&extra))
 177                                 break;
 178
 179                         list_splice_tail_init(&extra, &x->head);
 180                 } while (1);
 181         }
 182         spin_unlock_irqrestore(&x->lock, flags);
 183
 184         debug_fence_assert(fence);
 185 }
 186
 187 static void __i915_sw_fence_complete(struct i915_sw_fence *fence,
 188                                      struct list_head *continuation)
 189 {
 190         debug_fence_assert(fence);
 191
 192         if (!atomic_dec_and_test(&fence->pending))
 193                 return;
 194
 195         debug_fence_set_state(fence, DEBUG_FENCE_IDLE, DEBUG_FENCE_NOTIFY);
 196
 197         if (__i915_sw_fence_notify(fence, FENCE_COMPLETE) != NOTIFY_DONE)
 198                 return;
 199
 200         debug_fence_set_state(fence, DEBUG_FENCE_NOTIFY, DEBUG_FENCE_IDLE);
 201
 202         __i915_sw_fence_wake_up_all(fence, continuation);
 203
 204         debug_fence_destroy(fence);
 205         __i915_sw_fence_notify(fence, FENCE_FREE);
 206 }
 207
 208 void i915_sw_fence_complete(struct i915_sw_fence *fence)
 209 {
 210         debug_fence_assert(fence);
 211
 212         if (WARN_ON(i915_sw_fence_done(fence)))
 213                 return;
 214
 215         __i915_sw_fence_complete(fence, NULL);
 216 }
 217
 218 bool i915_sw_fence_await(struct i915_sw_fence *fence)
 219 {
 220         int pending;
 221
 222         /*
 223          * It is only safe to add a new await to the fence while it has
 224          * not yet been signaled (i.e. there are still existing signalers).
 225          */
 226         pending = atomic_read(&fence->pending);
 227         do {
 228                 if (pending < 1)
 229                         return false;
 230         } while (!atomic_try_cmpxchg(&fence->pending, &pending, pending + 1));
 231
 232         return true;
 233 }
 234
 235 void __i915_sw_fence_init(struct i915_sw_fence *fence,
 236                           i915_sw_fence_notify_t fn,
 237                           const char *name,
 238                           struct lock_class_key *key)
 239 {
 240         BUG_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK);
 241
 242         __init_waitqueue_head(&fence->wait, name, key);
 243         fence->flags = (unsigned long)fn;
 244
 245         i915_sw_fence_reinit(fence);
 246 }
 247
 248 void i915_sw_fence_reinit(struct i915_sw_fence *fence)
 249 {
 250         debug_fence_init(fence);
 251
 252         atomic_set(&fence->pending, 1);
 253         fence->error = 0;
 254
 255         I915_SW_FENCE_BUG_ON(!fence->flags);
 256         I915_SW_FENCE_BUG_ON(!list_empty(&fence->wait.head));
 257 }
 258
 259 void i915_sw_fence_commit(struct i915_sw_fence *fence)
 260 {
 261         debug_fence_activate(fence);
 262         i915_sw_fence_complete(fence);
 263 }
 264
 265 static int i915_sw_fence_wake(wait_queue_entry_t *wq, unsigned mode, int flags, void *key)
 266 {
 267         i915_sw_fence_set_error_once(wq->private, flags);
 268
 269         list_del(&wq->entry);
 270         __i915_sw_fence_complete(wq->private, key);
 271
 272         if (wq->flags & I915_SW_FENCE_FLAG_ALLOC)
 273                 kfree(wq);
 274         return 0;
 275 }
 276
 277 static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 278                                     const struct i915_sw_fence * const signaler)
 279 {
 280         wait_queue_entry_t *wq;
 281
 282         if (__test_and_set_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
 283                 return false;
 284
 285         if (fence == signaler)
 286                 return true;
 287
 288         list_for_each_entry(wq, &fence->wait.head, entry) {
 289                 if (wq->func != i915_sw_fence_wake)
 290                         continue;
 291
 292                 if (__i915_sw_fence_check_if_after(wq->private, signaler))
 293                         return true;
 294         }
 295
 296         return false;
 297 }
 298
 299 static void __i915_sw_fence_clear_checked_bit(struct i915_sw_fence *fence)
 300 {
 301         wait_queue_entry_t *wq;
 302
 303         if (!__test_and_clear_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
 304                 return;
 305
 306         list_for_each_entry(wq, &fence->wait.head, entry) {
 307                 if (wq->func != i915_sw_fence_wake)
 308                         continue;
 309
 310                 __i915_sw_fence_clear_checked_bit(wq->private);
 311         }
 312 }
 313
 314 static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 315                                   const struct i915_sw_fence * const signaler)
 316 {
 317         unsigned long flags;
 318         bool err;
 319
 320         if (!IS_ENABLED(CONFIG_DRM_I915_SW_FENCE_CHECK_DAG))
 321                 return false;
 322
 323         spin_lock_irqsave(&i915_sw_fence_lock, flags);
 324         err = __i915_sw_fence_check_if_after(fence, signaler);
 325         __i915_sw_fence_clear_checked_bit(fence);
 326         spin_unlock_irqrestore(&i915_sw_fence_lock, flags);
 327
 328         return err;
 329 }
 330
 331 static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 332                                           struct i915_sw_fence *signaler,
 333                                           wait_queue_entry_t *wq, gfp_t gfp)
 334 {
 335         unsigned long flags;
 336         int pending;
 337
 338         debug_fence_assert(fence);
 339         might_sleep_if(gfpflags_allow_blocking(gfp));
 340
 341         if (i915_sw_fence_done(signaler)) {
 342                 i915_sw_fence_set_error_once(fence, signaler->error);
 343                 return 0;
 344         }
 345
 346         debug_fence_assert(signaler);
 347
 348         /* The dependency graph must be acyclic. */
 349         if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
 350                 return -EINVAL;
 351
 352         pending = 0;
 353         if (!wq) {
 354                 wq = kmalloc(sizeof(*wq), gfp);
 355                 if (!wq) {
 356                         if (!gfpflags_allow_blocking(gfp))
 357                                 return -ENOMEM;
 358
 359                         i915_sw_fence_wait(signaler);
 360                         i915_sw_fence_set_error_once(fence, signaler->error);
 361                         return 0;
 362                 }
 363
 364                 pending |= I915_SW_FENCE_FLAG_ALLOC;
 365         }
 366
 367         INIT_LIST_HEAD(&wq->entry);
 368         wq->flags = pending;
 369         wq->func = i915_sw_fence_wake;
 370         wq->private = fence;
 371
 372         i915_sw_fence_await(fence);
 373
 374         spin_lock_irqsave(&signaler->wait.lock, flags);
 375         if (likely(!i915_sw_fence_done(signaler))) {
 376                 __add_wait_queue_entry_tail(&signaler->wait, wq);
 377                 pending = 1;
 378         } else {
 379                 i915_sw_fence_wake(wq, 0, signaler->error, NULL);
 380                 pending = 0;
 381         }
 382         spin_unlock_irqrestore(&signaler->wait.lock, flags);
 383
 384         return pending;
 385 }
 386
 387 int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 388                                  struct i915_sw_fence *signaler,
 389                                  wait_queue_entry_t *wq)
 390 {
 391         return __i915_sw_fence_await_sw_fence(fence, signaler, wq, 0);
 392 }
 393
 394 int i915_sw_fence_await_sw_fence_gfp(struct i915_sw_fence *fence,
 395                                      struct i915_sw_fence *signaler,
 396                                      gfp_t gfp)
 397 {
 398         return __i915_sw_fence_await_sw_fence(fence, signaler, NULL, gfp);
 399 }
 400
 401 struct i915_sw_dma_fence_cb_timer {
 402         struct i915_sw_dma_fence_cb base;
 403         struct dma_fence *dma;
 404         struct timer_list timer;
 405         struct irq_work work;
 406         struct rcu_head rcu;
 407 };
 408
 409 static void dma_i915_sw_fence_wake(struct dma_fence *dma,
 410                                    struct dma_fence_cb *data)
 411 {
 412         struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
 413
 414         i915_sw_fence_set_error_once(cb->fence, dma->error);
 415         i915_sw_fence_complete(cb->fence);
 416         kfree(cb);
 417 }
 418
 419 static void timer_i915_sw_fence_wake(struct timer_list *t)
 420 {
 421         struct i915_sw_dma_fence_cb_timer *cb = from_timer(cb, t, timer);
 422         struct i915_sw_fence *fence;
 423
 424         fence = xchg(&cb->base.fence, NULL);
 425         if (!fence)
 426                 return;
 427
 428         pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",
 429                   cb->dma->ops->get_driver_name(cb->dma),
 430                   cb->dma->ops->get_timeline_name(cb->dma),
 431                   cb->dma->seqno,
 432                   i915_sw_fence_debug_hint(fence));
 433
 434         i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
 435         i915_sw_fence_complete(fence);
 436 }
 437
 438 static void dma_i915_sw_fence_wake_timer(struct dma_fence *dma,
 439                                          struct dma_fence_cb *data)
 440 {
 441         struct i915_sw_dma_fence_cb_timer *cb =
 442                 container_of(data, typeof(*cb), base.base);
 443         struct i915_sw_fence *fence;
 444
 445         fence = xchg(&cb->base.fence, NULL);
 446         if (fence) {
 447                 i915_sw_fence_set_error_once(fence, dma->error);
 448                 i915_sw_fence_complete(fence);
 449         }
 450
 451         irq_work_queue(&cb->work);
 452 }
 453
 454 static void irq_i915_sw_fence_work(struct irq_work *wrk)
 455 {
 456         struct i915_sw_dma_fence_cb_timer *cb =
 457                 container_of(wrk, typeof(*cb), work);
 458
 459         del_timer_sync(&cb->timer);
 460         dma_fence_put(cb->dma);
 461
 462         kfree_rcu(cb, rcu);
 463 }
 464
 465 int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
 466                                   struct dma_fence *dma,
 467                                   unsigned long timeout,
 468                                   gfp_t gfp)
 469 {
 470         struct i915_sw_dma_fence_cb *cb;
 471         dma_fence_func_t func;
 472         int ret;
 473
 474         debug_fence_assert(fence);
 475         might_sleep_if(gfpflags_allow_blocking(gfp));
 476
 477         if (dma_fence_is_signaled(dma)) {
 478                 i915_sw_fence_set_error_once(fence, dma->error);
 479                 return 0;
 480         }
 481
 482         cb = kmalloc(timeout ?
 483                      sizeof(struct i915_sw_dma_fence_cb_timer) :
 484                      sizeof(struct i915_sw_dma_fence_cb),
 485                      gfp);
 486         if (!cb) {
 487                 if (!gfpflags_allow_blocking(gfp))
 488                         return -ENOMEM;
 489
 490                 ret = dma_fence_wait(dma, false);
 491                 if (ret)
 492                         return ret;
 493
 494                 i915_sw_fence_set_error_once(fence, dma->error);
 495                 return 0;
 496         }
 497
 498         cb->fence = fence;
 499         i915_sw_fence_await(fence);
 500
 501         func = dma_i915_sw_fence_wake;
 502         if (timeout) {
 503                 struct i915_sw_dma_fence_cb_timer *timer =
 504                         container_of(cb, typeof(*timer), base);
 505
 506                 timer->dma = dma_fence_get(dma);
 507                 init_irq_work(&timer->work, irq_i915_sw_fence_work);
 508
 509                 timer_setup(&timer->timer,
 510                             timer_i915_sw_fence_wake, TIMER_IRQSAFE);
 511                 mod_timer(&timer->timer, round_jiffies_up(jiffies + timeout));
 512
 513                 func = dma_i915_sw_fence_wake_timer;
 514         }
 515
 516         ret = dma_fence_add_callback(dma, &cb->base, func);
 517         if (ret == 0) {
 518                 ret = 1;
 519         } else {
 520                 func(dma, &cb->base);
 521                 if (ret == -ENOENT) /* fence already signaled */
 522                         ret = 0;
 523         }
 524
 525         return ret;
 526 }
 527
 528 static void __dma_i915_sw_fence_wake(struct dma_fence *dma,
 529                                      struct dma_fence_cb *data)
 530 {
 531         struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
 532
 533         i915_sw_fence_set_error_once(cb->fence, dma->error);
 534         i915_sw_fence_complete(cb->fence);
 535 }
 536
 537 int __i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
 538                                     struct dma_fence *dma,
 539                                     struct i915_sw_dma_fence_cb *cb)
 540 {
 541         int ret;
 542
 543         debug_fence_assert(fence);
 544
 545         if (dma_fence_is_signaled(dma)) {
 546                 i915_sw_fence_set_error_once(fence, dma->error);
 547                 return 0;
 548         }
 549
 550         cb->fence = fence;
 551         i915_sw_fence_await(fence);
 552
 553         ret = 1;
 554         if (dma_fence_add_callback(dma, &cb->base, __dma_i915_sw_fence_wake)) {
 555                 /* fence already signaled */
 556                 __dma_i915_sw_fence_wake(dma, &cb->base);
 557                 ret = 0;
 558         }
 559
 560         return ret;
 561 }
 562
 563 int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
 564                                     struct dma_resv *resv,
 565                                     const struct dma_fence_ops *exclude,
 566                                     bool write,
 567                                     unsigned long timeout,
 568                                     gfp_t gfp)
 569 {
 570         struct dma_fence *excl;
 571         int ret = 0, pending;
 572
 573         debug_fence_assert(fence);
 574         might_sleep_if(gfpflags_allow_blocking(gfp));
 575
 576         if (write) {
 577                 struct dma_fence **shared;
 578                 unsigned int count, i;
 579
 580                 ret = dma_resv_get_fences_rcu(resv, &excl, &count, &shared);
 581                 if (ret)
 582                         return ret;
 583
 584                 for (i = 0; i < count; i++) {
 585                         if (shared[i]->ops == exclude)
 586                                 continue;
 587
 588                         pending = i915_sw_fence_await_dma_fence(fence,
 589                                                                 shared[i],
 590                                                                 timeout,
 591                                                                 gfp);
 592                         if (pending < 0) {
 593                                 ret = pending;
 594                                 break;
 595                         }
 596
 597                         ret |= pending;
 598                 }
 599
 600                 for (i = 0; i < count; i++)
 601                         dma_fence_put(shared[i]);
 602                 kfree(shared);
 603         } else {
 604                 excl = dma_resv_get_excl_rcu(resv);
 605         }
 606
 607         if (ret >= 0 && excl && excl->ops != exclude) {
 608                 pending = i915_sw_fence_await_dma_fence(fence,
 609                                                         excl,
 610                                                         timeout,
 611                                                         gfp);
 612                 if (pending < 0)
 613                         ret = pending;
 614                 else
 615                         ret |= pending;
 616         }
 617
 618         dma_fence_put(excl);
 619
 620         return ret;
 621 }
 622
 623 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 624 #include "selftests/lib_sw_fence.c"
 625 #include "selftests/i915_sw_fence.c"
 626 #endif