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 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                                 pos->func(pos,
 168                                           TASK_NORMAL, fence->error,
 169                                           &extra);
 170                         }
 171
 172                         if (list_empty(&extra))
 173                                 break;
 174
 175                         list_splice_tail_init(&extra, &x->head);
 176                 } while (1);
 177         }
 178         spin_unlock_irqrestore(&x->lock, flags);
 179
 180         debug_fence_assert(fence);
 181 }
 182
 183 static void __i915_sw_fence_complete(struct i915_sw_fence *fence,
 184                                      struct list_head *continuation)
 185 {
 186         debug_fence_assert(fence);
 187
 188         if (!atomic_dec_and_test(&fence->pending))
 189                 return;
 190
 191         debug_fence_set_state(fence, DEBUG_FENCE_IDLE, DEBUG_FENCE_NOTIFY);
 192
 193         if (__i915_sw_fence_notify(fence, FENCE_COMPLETE) != NOTIFY_DONE)
 194                 return;
 195
 196         debug_fence_set_state(fence, DEBUG_FENCE_NOTIFY, DEBUG_FENCE_IDLE);
 197
 198         __i915_sw_fence_wake_up_all(fence, continuation);
 199
 200         debug_fence_destroy(fence);
 201         __i915_sw_fence_notify(fence, FENCE_FREE);
 202 }
 203
 204 void i915_sw_fence_complete(struct i915_sw_fence *fence)
 205 {
 206         debug_fence_assert(fence);
 207
 208         if (WARN_ON(i915_sw_fence_done(fence)))
 209                 return;
 210
 211         __i915_sw_fence_complete(fence, NULL);
 212 }
 213
 214 bool i915_sw_fence_await(struct i915_sw_fence *fence)
 215 {
 216         int pending;
 217
 218         /*
 219          * It is only safe to add a new await to the fence while it has
 220          * not yet been signaled (i.e. there are still existing signalers).
 221          */
 222         pending = atomic_read(&fence->pending);
 223         do {
 224                 if (pending < 1)
 225                         return false;
 226         } while (!atomic_try_cmpxchg(&fence->pending, &pending, pending + 1));
 227
 228         return true;
 229 }
 230
 231 void __i915_sw_fence_init(struct i915_sw_fence *fence,
 232                           i915_sw_fence_notify_t fn,
 233                           const char *name,
 234                           struct lock_class_key *key)
 235 {
 236         BUG_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK);
 237
 238         __init_waitqueue_head(&fence->wait, name, key);
 239         fence->flags = (unsigned long)fn;
 240
 241         i915_sw_fence_reinit(fence);
 242 }
 243
 244 void i915_sw_fence_reinit(struct i915_sw_fence *fence)
 245 {
 246         debug_fence_init(fence);
 247
 248         atomic_set(&fence->pending, 1);
 249         fence->error = 0;
 250
 251         I915_SW_FENCE_BUG_ON(!fence->flags);
 252         I915_SW_FENCE_BUG_ON(!list_empty(&fence->wait.head));
 253 }
 254
 255 void i915_sw_fence_commit(struct i915_sw_fence *fence)
 256 {
 257         debug_fence_activate(fence);
 258         i915_sw_fence_complete(fence);
 259 }
 260
 261 static int i915_sw_fence_wake(wait_queue_entry_t *wq, unsigned mode, int flags, void *key)
 262 {
 263         i915_sw_fence_set_error_once(wq->private, flags);
 264
 265         list_del(&wq->entry);
 266         __i915_sw_fence_complete(wq->private, key);
 267
 268         if (wq->flags & I915_SW_FENCE_FLAG_ALLOC)
 269                 kfree(wq);
 270         return 0;
 271 }
 272
 273 static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 274                                     const struct i915_sw_fence * const signaler)
 275 {
 276         wait_queue_entry_t *wq;
 277
 278         if (__test_and_set_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
 279                 return false;
 280
 281         if (fence == signaler)
 282                 return true;
 283
 284         list_for_each_entry(wq, &fence->wait.head, entry) {
 285                 if (wq->func != i915_sw_fence_wake)
 286                         continue;
 287
 288                 if (__i915_sw_fence_check_if_after(wq->private, signaler))
 289                         return true;
 290         }
 291
 292         return false;
 293 }
 294
 295 static void __i915_sw_fence_clear_checked_bit(struct i915_sw_fence *fence)
 296 {
 297         wait_queue_entry_t *wq;
 298
 299         if (!__test_and_clear_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
 300                 return;
 301
 302         list_for_each_entry(wq, &fence->wait.head, entry) {
 303                 if (wq->func != i915_sw_fence_wake)
 304                         continue;
 305
 306                 __i915_sw_fence_clear_checked_bit(wq->private);
 307         }
 308 }
 309
 310 static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 311                                   const struct i915_sw_fence * const signaler)
 312 {
 313         unsigned long flags;
 314         bool err;
 315
 316         if (!IS_ENABLED(CONFIG_DRM_I915_SW_FENCE_CHECK_DAG))
 317                 return false;
 318
 319         spin_lock_irqsave(&i915_sw_fence_lock, flags);
 320         err = __i915_sw_fence_check_if_after(fence, signaler);
 321         __i915_sw_fence_clear_checked_bit(fence);
 322         spin_unlock_irqrestore(&i915_sw_fence_lock, flags);
 323
 324         return err;
 325 }
 326
 327 static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 328                                           struct i915_sw_fence *signaler,
 329                                           wait_queue_entry_t *wq, gfp_t gfp)
 330 {
 331         unsigned long flags;
 332         int pending;
 333
 334         debug_fence_assert(fence);
 335         might_sleep_if(gfpflags_allow_blocking(gfp));
 336
 337         if (i915_sw_fence_done(signaler)) {
 338                 i915_sw_fence_set_error_once(fence, signaler->error);
 339                 return 0;
 340         }
 341
 342         debug_fence_assert(signaler);
 343
 344         /* The dependency graph must be acyclic. */
 345         if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
 346                 return -EINVAL;
 347
 348         pending = 0;
 349         if (!wq) {
 350                 wq = kmalloc(sizeof(*wq), gfp);
 351                 if (!wq) {
 352                         if (!gfpflags_allow_blocking(gfp))
 353                                 return -ENOMEM;
 354
 355                         i915_sw_fence_wait(signaler);
 356                         i915_sw_fence_set_error_once(fence, signaler->error);
 357                         return 0;
 358                 }
 359
 360                 pending |= I915_SW_FENCE_FLAG_ALLOC;
 361         }
 362
 363         INIT_LIST_HEAD(&wq->entry);
 364         wq->flags = pending;
 365         wq->func = i915_sw_fence_wake;
 366         wq->private = fence;
 367
 368         i915_sw_fence_await(fence);
 369
 370         spin_lock_irqsave(&signaler->wait.lock, flags);
 371         if (likely(!i915_sw_fence_done(signaler))) {
 372                 __add_wait_queue_entry_tail(&signaler->wait, wq);
 373                 pending = 1;
 374         } else {
 375                 i915_sw_fence_wake(wq, 0, signaler->error, NULL);
 376                 pending = 0;
 377         }
 378         spin_unlock_irqrestore(&signaler->wait.lock, flags);
 379
 380         return pending;
 381 }
 382
 383 int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 384                                  struct i915_sw_fence *signaler,
 385                                  wait_queue_entry_t *wq)
 386 {
 387         return __i915_sw_fence_await_sw_fence(fence, signaler, wq, 0);
 388 }
 389
 390 int i915_sw_fence_await_sw_fence_gfp(struct i915_sw_fence *fence,
 391                                      struct i915_sw_fence *signaler,
 392                                      gfp_t gfp)
 393 {
 394         return __i915_sw_fence_await_sw_fence(fence, signaler, NULL, gfp);
 395 }
 396
 397 struct i915_sw_dma_fence_cb_timer {
 398         struct i915_sw_dma_fence_cb base;
 399         struct dma_fence *dma;
 400         struct timer_list timer;
 401         struct irq_work work;
 402         struct rcu_head rcu;
 403 };
 404
 405 static void dma_i915_sw_fence_wake(struct dma_fence *dma,
 406                                    struct dma_fence_cb *data)
 407 {
 408         struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
 409
 410         i915_sw_fence_set_error_once(cb->fence, dma->error);
 411         i915_sw_fence_complete(cb->fence);
 412         kfree(cb);
 413 }
 414
 415 static void timer_i915_sw_fence_wake(struct timer_list *t)
 416 {
 417         struct i915_sw_dma_fence_cb_timer *cb = from_timer(cb, t, timer);
 418         struct i915_sw_fence *fence;
 419
 420         fence = xchg(&cb->base.fence, NULL);
 421         if (!fence)
 422                 return;
 423
 424         pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",
 425                   cb->dma->ops->get_driver_name(cb->dma),
 426                   cb->dma->ops->get_timeline_name(cb->dma),
 427                   cb->dma->seqno,
 428                   i915_sw_fence_debug_hint(fence));
 429
 430         i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
 431         i915_sw_fence_complete(fence);
 432 }
 433
 434 static void dma_i915_sw_fence_wake_timer(struct dma_fence *dma,
 435                                          struct dma_fence_cb *data)
 436 {
 437         struct i915_sw_dma_fence_cb_timer *cb =
 438                 container_of(data, typeof(*cb), base.base);
 439         struct i915_sw_fence *fence;
 440
 441         fence = xchg(&cb->base.fence, NULL);
 442         if (fence) {
 443                 i915_sw_fence_set_error_once(fence, dma->error);
 444                 i915_sw_fence_complete(fence);
 445         }
 446
 447         irq_work_queue(&cb->work);
 448 }
 449
 450 static void irq_i915_sw_fence_work(struct irq_work *wrk)
 451 {
 452         struct i915_sw_dma_fence_cb_timer *cb =
 453                 container_of(wrk, typeof(*cb), work);
 454
 455         del_timer_sync(&cb->timer);
 456         dma_fence_put(cb->dma);
 457
 458         kfree_rcu(cb, rcu);
 459 }
 460
 461 int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
 462                                   struct dma_fence *dma,
 463                                   unsigned long timeout,
 464                                   gfp_t gfp)
 465 {
 466         struct i915_sw_dma_fence_cb *cb;
 467         dma_fence_func_t func;
 468         int ret;
 469
 470         debug_fence_assert(fence);
 471         might_sleep_if(gfpflags_allow_blocking(gfp));
 472
 473         if (dma_fence_is_signaled(dma)) {
 474                 i915_sw_fence_set_error_once(fence, dma->error);
 475                 return 0;
 476         }
 477
 478         cb = kmalloc(timeout ?
 479                      sizeof(struct i915_sw_dma_fence_cb_timer) :
 480                      sizeof(struct i915_sw_dma_fence_cb),
 481                      gfp);
 482         if (!cb) {
 483                 if (!gfpflags_allow_blocking(gfp))
 484                         return -ENOMEM;
 485
 486                 ret = dma_fence_wait(dma, false);
 487                 if (ret)
 488                         return ret;
 489
 490                 i915_sw_fence_set_error_once(fence, dma->error);
 491                 return 0;
 492         }
 493
 494         cb->fence = fence;
 495         i915_sw_fence_await(fence);
 496
 497         func = dma_i915_sw_fence_wake;
 498         if (timeout) {
 499                 struct i915_sw_dma_fence_cb_timer *timer =
 500                         container_of(cb, typeof(*timer), base);
 501
 502                 timer->dma = dma_fence_get(dma);
 503                 init_irq_work(&timer->work, irq_i915_sw_fence_work);
 504
 505                 timer_setup(&timer->timer,
 506                             timer_i915_sw_fence_wake, TIMER_IRQSAFE);
 507                 mod_timer(&timer->timer, round_jiffies_up(jiffies + timeout));
 508
 509                 func = dma_i915_sw_fence_wake_timer;
 510         }
 511
 512         ret = dma_fence_add_callback(dma, &cb->base, func);
 513         if (ret == 0) {
 514                 ret = 1;
 515         } else {
 516                 func(dma, &cb->base);
 517                 if (ret == -ENOENT) /* fence already signaled */
 518                         ret = 0;
 519         }
 520
 521         return ret;
 522 }
 523
 524 static void __dma_i915_sw_fence_wake(struct dma_fence *dma,
 525                                      struct dma_fence_cb *data)
 526 {
 527         struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
 528
 529         i915_sw_fence_set_error_once(cb->fence, dma->error);
 530         i915_sw_fence_complete(cb->fence);
 531 }
 532
 533 int __i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
 534                                     struct dma_fence *dma,
 535                                     struct i915_sw_dma_fence_cb *cb)
 536 {
 537         int ret;
 538
 539         debug_fence_assert(fence);
 540
 541         if (dma_fence_is_signaled(dma)) {
 542                 i915_sw_fence_set_error_once(fence, dma->error);
 543                 return 0;
 544         }
 545
 546         cb->fence = fence;
 547         i915_sw_fence_await(fence);
 548
 549         ret = 1;
 550         if (dma_fence_add_callback(dma, &cb->base, __dma_i915_sw_fence_wake)) {
 551                 /* fence already signaled */
 552                 __dma_i915_sw_fence_wake(dma, &cb->base);
 553                 ret = 0;
 554         }
 555
 556         return ret;
 557 }
 558
 559 int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
 560                                     struct dma_resv *resv,
 561                                     const struct dma_fence_ops *exclude,
 562                                     bool write,
 563                                     unsigned long timeout,
 564                                     gfp_t gfp)
 565 {
 566         struct dma_fence *excl;
 567         int ret = 0, pending;
 568
 569         debug_fence_assert(fence);
 570         might_sleep_if(gfpflags_allow_blocking(gfp));
 571
 572         if (write) {
 573                 struct dma_fence **shared;
 574                 unsigned int count, i;
 575
 576                 ret = dma_resv_get_fences_rcu(resv, &excl, &count, &shared);
 577                 if (ret)
 578                         return ret;
 579
 580                 for (i = 0; i < count; i++) {
 581                         if (shared[i]->ops == exclude)
 582                                 continue;
 583
 584                         pending = i915_sw_fence_await_dma_fence(fence,
 585                                                                 shared[i],
 586                                                                 timeout,
 587                                                                 gfp);
 588                         if (pending < 0) {
 589                                 ret = pending;
 590                                 break;
 591                         }
 592
 593                         ret |= pending;
 594                 }
 595
 596                 for (i = 0; i < count; i++)
 597                         dma_fence_put(shared[i]);
 598                 kfree(shared);
 599         } else {
 600                 excl = dma_resv_get_excl_rcu(resv);
 601         }
 602
 603         if (ret >= 0 && excl && excl->ops != exclude) {
 604                 pending = i915_sw_fence_await_dma_fence(fence,
 605                                                         excl,
 606                                                         timeout,
 607                                                         gfp);
 608                 if (pending < 0)
 609                         ret = pending;
 610                 else
 611                         ret |= pending;
 612         }
 613
 614         dma_fence_put(excl);
 615
 616         return ret;
 617 }
 618
 619 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 620 #include "selftests/lib_sw_fence.c"
 621 #include "selftests/i915_sw_fence.c"
 622 #endif