drivers/gpu/drm/scheduler/sched_main.c

   1 /*
   2  * Copyright 2015 Advanced Micro Devices, Inc.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20  * OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  */
  23
  24 /**
  25  * DOC: Overview
  26  *
  27  * The GPU scheduler provides entities which allow userspace to push jobs
  28  * into software queues which are then scheduled on a hardware run queue.
  29  * The software queues have a priority among them. The scheduler selects the entities
  30  * from the run queue using a FIFO. The scheduler provides dependency handling
  31  * features among jobs. The driver is supposed to provide callback functions for
  32  * backend operations to the scheduler like submitting a job to hardware run queue,
  33  * returning the dependencies of a job etc.
  34  *
  35  * The organisation of the scheduler is the following:
  36  *
  37  * 1. Each hw run queue has one scheduler
  38  * 2. Each scheduler has multiple run queues with different priorities
  39  *    (e.g., HIGH_HW,HIGH_SW, KERNEL, NORMAL)
  40  * 3. Each scheduler run queue has a queue of entities to schedule
  41  * 4. Entities themselves maintain a queue of jobs that will be scheduled on
  42  *    the hardware.
  43  *
  44  * The jobs in a entity are always scheduled in the order that they were pushed.
  45  */
  46
  47 #include <linux/kthread.h>
  48 #include <linux/wait.h>
  49 #include <linux/sched.h>
  50 #include <uapi/linux/sched/types.h>
  51 #include <drm/drmP.h>
  52 #include <drm/gpu_scheduler.h>
  53 #include <drm/spsc_queue.h>
  54
  55 #define CREATE_TRACE_POINTS
  56 #include "gpu_scheduler_trace.h"
  57
  58 #define to_drm_sched_job(sched_job)             \
  59                 container_of((sched_job), struct drm_sched_job, queue_node)
  60
  61 static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb);
  62
  63 /**
  64  * drm_sched_rq_init - initialize a given run queue struct
  65  *
  66  * @rq: scheduler run queue
  67  *
  68  * Initializes a scheduler runqueue.
  69  */
  70 static void drm_sched_rq_init(struct drm_gpu_scheduler *sched,
  71                               struct drm_sched_rq *rq)
  72 {
  73         spin_lock_init(&rq->lock);
  74         INIT_LIST_HEAD(&rq->entities);
  75         rq->current_entity = NULL;
  76         rq->sched = sched;
  77 }
  78
  79 /**
  80  * drm_sched_rq_add_entity - add an entity
  81  *
  82  * @rq: scheduler run queue
  83  * @entity: scheduler entity
  84  *
  85  * Adds a scheduler entity to the run queue.
  86  */
  87 void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
  88                              struct drm_sched_entity *entity)
  89 {
  90         if (!list_empty(&entity->list))
  91                 return;
  92         spin_lock(&rq->lock);
  93         list_add_tail(&entity->list, &rq->entities);
  94         spin_unlock(&rq->lock);
  95 }
  96
  97 /**
  98  * drm_sched_rq_remove_entity - remove an entity
  99  *
 100  * @rq: scheduler run queue
 101  * @entity: scheduler entity
 102  *
 103  * Removes a scheduler entity from the run queue.
 104  */
 105 void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
 106                                 struct drm_sched_entity *entity)
 107 {
 108         if (list_empty(&entity->list))
 109                 return;
 110         spin_lock(&rq->lock);
 111         list_del_init(&entity->list);
 112         if (rq->current_entity == entity)
 113                 rq->current_entity = NULL;
 114         spin_unlock(&rq->lock);
 115 }
 116
 117 /**
 118  * drm_sched_rq_select_entity - Select an entity which could provide a job to run
 119  *
 120  * @rq: scheduler run queue to check.
 121  *
 122  * Try to find a ready entity, returns NULL if none found.
 123  */
 124 static struct drm_sched_entity *
 125 drm_sched_rq_select_entity(struct drm_sched_rq *rq)
 126 {
 127         struct drm_sched_entity *entity;
 128
 129         spin_lock(&rq->lock);
 130
 131         entity = rq->current_entity;
 132         if (entity) {
 133                 list_for_each_entry_continue(entity, &rq->entities, list) {
 134                         if (drm_sched_entity_is_ready(entity)) {
 135                                 rq->current_entity = entity;
 136                                 spin_unlock(&rq->lock);
 137                                 return entity;
 138                         }
 139                 }
 140         }
 141
 142         list_for_each_entry(entity, &rq->entities, list) {
 143
 144                 if (drm_sched_entity_is_ready(entity)) {
 145                         rq->current_entity = entity;
 146                         spin_unlock(&rq->lock);
 147                         return entity;
 148                 }
 149
 150                 if (entity == rq->current_entity)
 151                         break;
 152         }
 153
 154         spin_unlock(&rq->lock);
 155
 156         return NULL;
 157 }
 158
 159 /**
 160  * drm_sched_dependency_optimized
 161  *
 162  * @fence: the dependency fence
 163  * @entity: the entity which depends on the above fence
 164  *
 165  * Returns true if the dependency can be optimized and false otherwise
 166  */
 167 bool drm_sched_dependency_optimized(struct dma_fence* fence,
 168                                     struct drm_sched_entity *entity)
 169 {
 170         struct drm_gpu_scheduler *sched = entity->rq->sched;
 171         struct drm_sched_fence *s_fence;
 172
 173         if (!fence || dma_fence_is_signaled(fence))
 174                 return false;
 175         if (fence->context == entity->fence_context)
 176                 return true;
 177         s_fence = to_drm_sched_fence(fence);
 178         if (s_fence && s_fence->sched == sched)
 179                 return true;
 180
 181         return false;
 182 }
 183 EXPORT_SYMBOL(drm_sched_dependency_optimized);
 184
 185 /**
 186  * drm_sched_start_timeout - start timeout for reset worker
 187  *
 188  * @sched: scheduler instance to start the worker for
 189  *
 190  * Start the timeout for the given scheduler.
 191  */
 192 static void drm_sched_start_timeout(struct drm_gpu_scheduler *sched)
 193 {
 194         if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
 195             !list_empty(&sched->ring_mirror_list))
 196                 schedule_delayed_work(&sched->work_tdr, sched->timeout);
 197 }
 198
 199 /**
 200  * drm_sched_fault - immediately start timeout handler
 201  *
 202  * @sched: scheduler where the timeout handling should be started.
 203  *
 204  * Start timeout handling immediately when the driver detects a hardware fault.
 205  */
 206 void drm_sched_fault(struct drm_gpu_scheduler *sched)
 207 {
 208         mod_delayed_work(system_wq, &sched->work_tdr, 0);
 209 }
 210 EXPORT_SYMBOL(drm_sched_fault);
 211
 212 /**
 213  * drm_sched_suspend_timeout - Suspend scheduler job timeout
 214  *
 215  * @sched: scheduler instance for which to suspend the timeout
 216  *
 217  * Suspend the delayed work timeout for the scheduler. This is done by
 218  * modifying the delayed work timeout to an arbitrary large value,
 219  * MAX_SCHEDULE_TIMEOUT in this case. Note that this function can be
 220  * called from an IRQ context.
 221  *
 222  * Returns the timeout remaining
 223  *
 224  */
 225 unsigned long drm_sched_suspend_timeout(struct drm_gpu_scheduler *sched)
 226 {
 227         unsigned long sched_timeout, now = jiffies;
 228
 229         sched_timeout = sched->work_tdr.timer.expires;
 230
 231         /*
 232          * Modify the timeout to an arbitrarily large value. This also prevents
 233          * the timeout to be restarted when new submissions arrive
 234          */
 235         if (mod_delayed_work(system_wq, &sched->work_tdr, MAX_SCHEDULE_TIMEOUT)
 236                         && time_after(sched_timeout, now))
 237                 return sched_timeout - now;
 238         else
 239                 return sched->timeout;
 240 }
 241 EXPORT_SYMBOL(drm_sched_suspend_timeout);
 242
 243 /**
 244  * drm_sched_resume_timeout - Resume scheduler job timeout
 245  *
 246  * @sched: scheduler instance for which to resume the timeout
 247  * @remaining: remaining timeout
 248  *
 249  * Resume the delayed work timeout for the scheduler. Note that
 250  * this function can be called from an IRQ context.
 251  */
 252 void drm_sched_resume_timeout(struct drm_gpu_scheduler *sched,
 253                 unsigned long remaining)
 254 {
 255         unsigned long flags;
 256
 257         spin_lock_irqsave(&sched->job_list_lock, flags);
 258
 259         if (list_empty(&sched->ring_mirror_list))
 260                 cancel_delayed_work(&sched->work_tdr);
 261         else
 262                 mod_delayed_work(system_wq, &sched->work_tdr, remaining);
 263
 264         spin_unlock_irqrestore(&sched->job_list_lock, flags);
 265 }
 266 EXPORT_SYMBOL(drm_sched_resume_timeout);
 267
 268 static void drm_sched_job_begin(struct drm_sched_job *s_job)
 269 {
 270         struct drm_gpu_scheduler *sched = s_job->sched;
 271         unsigned long flags;
 272
 273         spin_lock_irqsave(&sched->job_list_lock, flags);
 274         list_add_tail(&s_job->node, &sched->ring_mirror_list);
 275         drm_sched_start_timeout(sched);
 276         spin_unlock_irqrestore(&sched->job_list_lock, flags);
 277 }
 278
 279 static void drm_sched_job_timedout(struct work_struct *work)
 280 {
 281         struct drm_gpu_scheduler *sched;
 282         struct drm_sched_job *job;
 283         unsigned long flags;
 284
 285         sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
 286         job = list_first_entry_or_null(&sched->ring_mirror_list,
 287                                        struct drm_sched_job, node);
 288
 289         if (job) {
 290                 job->sched->ops->timedout_job(job);
 291
 292                 /*
 293                  * Guilty job did complete and hence needs to be manually removed
 294                  * See drm_sched_stop doc.
 295                  */
 296                 if (sched->free_guilty) {
 297                         job->sched->ops->free_job(job);
 298                         sched->free_guilty = false;
 299                 }
 300         }
 301
 302         spin_lock_irqsave(&sched->job_list_lock, flags);
 303         drm_sched_start_timeout(sched);
 304         spin_unlock_irqrestore(&sched->job_list_lock, flags);
 305 }
 306
 307  /**
 308   * drm_sched_increase_karma - Update sched_entity guilty flag
 309   *
 310   * @bad: The job guilty of time out
 311   *
 312   * Increment on every hang caused by the 'bad' job. If this exceeds the hang
 313   * limit of the scheduler then the respective sched entity is marked guilty and
 314   * jobs from it will not be scheduled further
 315   */
 316 void drm_sched_increase_karma(struct drm_sched_job *bad)
 317 {
 318         int i;
 319         struct drm_sched_entity *tmp;
 320         struct drm_sched_entity *entity;
 321         struct drm_gpu_scheduler *sched = bad->sched;
 322
 323         /* don't increase @bad's karma if it's from KERNEL RQ,
 324          * because sometimes GPU hang would cause kernel jobs (like VM updating jobs)
 325          * corrupt but keep in mind that kernel jobs always considered good.
 326          */
 327         if (bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
 328                 atomic_inc(&bad->karma);
 329                 for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_KERNEL;
 330                      i++) {
 331                         struct drm_sched_rq *rq = &sched->sched_rq[i];
 332
 333                         spin_lock(&rq->lock);
 334                         list_for_each_entry_safe(entity, tmp, &rq->entities, list) {
 335                                 if (bad->s_fence->scheduled.context ==
 336                                     entity->fence_context) {
 337                                         if (atomic_read(&bad->karma) >
 338                                             bad->sched->hang_limit)
 339                                                 if (entity->guilty)
 340                                                         atomic_set(entity->guilty, 1);
 341                                         break;
 342                                 }
 343                         }
 344                         spin_unlock(&rq->lock);
 345                         if (&entity->list != &rq->entities)
 346                                 break;
 347                 }
 348         }
 349 }
 350 EXPORT_SYMBOL(drm_sched_increase_karma);
 351
 352 /**
 353  * drm_sched_stop - stop the scheduler
 354  *
 355  * @sched: scheduler instance
 356  * @bad: job which caused the time out
 357  *
 358  * Stop the scheduler and also removes and frees all completed jobs.
 359  * Note: bad job will not be freed as it might be used later and so it's
 360  * callers responsibility to release it manually if it's not part of the
 361  * mirror list any more.
 362  *
 363  */
 364 void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
 365 {
 366         struct drm_sched_job *s_job, *tmp;
 367         unsigned long flags;
 368
 369         kthread_park(sched->thread);
 370
 371         /*
 372          * Iterate the job list from later to  earlier one and either deactive
 373          * their HW callbacks or remove them from mirror list if they already
 374          * signaled.
 375          * This iteration is thread safe as sched thread is stopped.
 376          */
 377         list_for_each_entry_safe_reverse(s_job, tmp, &sched->ring_mirror_list, node) {
 378                 if (s_job->s_fence->parent &&
 379                     dma_fence_remove_callback(s_job->s_fence->parent,
 380                                               &s_job->cb)) {
 381                         atomic_dec(&sched->hw_rq_count);
 382                 } else {
 383                         /*
 384                          * remove job from ring_mirror_list.
 385                          * Locking here is for concurrent resume timeout
 386                          */
 387                         spin_lock_irqsave(&sched->job_list_lock, flags);
 388                         list_del_init(&s_job->node);
 389                         spin_unlock_irqrestore(&sched->job_list_lock, flags);
 390
 391                         /*
 392                          * Wait for job's HW fence callback to finish using s_job
 393                          * before releasing it.
 394                          *
 395                          * Job is still alive so fence refcount at least 1
 396                          */
 397                         dma_fence_wait(&s_job->s_fence->finished, false);
 398
 399                         /*
 400                          * We must keep bad job alive for later use during
 401                          * recovery by some of the drivers but leave a hint
 402                          * that the guilty job must be released.
 403                          */
 404                         if (bad != s_job)
 405                                 sched->ops->free_job(s_job);
 406                         else
 407                                 sched->free_guilty = true;
 408                 }
 409         }
 410
 411         /*
 412          * Stop pending timer in flight as we rearm it in  drm_sched_start. This
 413          * avoids the pending timeout work in progress to fire right away after
 414          * this TDR finished and before the newly restarted jobs had a
 415          * chance to complete.
 416          */
 417         cancel_delayed_work(&sched->work_tdr);
 418 }
 419
 420 EXPORT_SYMBOL(drm_sched_stop);
 421
 422 /**
 423  * drm_sched_job_recovery - recover jobs after a reset
 424  *
 425  * @sched: scheduler instance
 426  * @full_recovery: proceed with complete sched restart
 427  *
 428  */
 429 void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
 430 {
 431         struct drm_sched_job *s_job, *tmp;
 432         unsigned long flags;
 433         int r;
 434
 435         /*
 436          * Locking the list is not required here as the sched thread is parked
 437          * so no new jobs are being inserted or removed. Also concurrent
 438          * GPU recovers can't run in parallel.
 439          */
 440         list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
 441                 struct dma_fence *fence = s_job->s_fence->parent;
 442
 443                 atomic_inc(&sched->hw_rq_count);
 444
 445                 if (!full_recovery)
 446                         continue;
 447
 448                 if (fence) {
 449                         r = dma_fence_add_callback(fence, &s_job->cb,
 450                                                    drm_sched_process_job);
 451                         if (r == -ENOENT)
 452                                 drm_sched_process_job(fence, &s_job->cb);
 453                         else if (r)
 454                                 DRM_ERROR("fence add callback failed (%d)\n",
 455                                           r);
 456                 } else
 457                         drm_sched_process_job(NULL, &s_job->cb);
 458         }
 459
 460         if (full_recovery) {
 461                 spin_lock_irqsave(&sched->job_list_lock, flags);
 462                 drm_sched_start_timeout(sched);
 463                 spin_unlock_irqrestore(&sched->job_list_lock, flags);
 464         }
 465
 466         kthread_unpark(sched->thread);
 467 }
 468 EXPORT_SYMBOL(drm_sched_start);
 469
 470 /**
 471  * drm_sched_resubmit_jobs - helper to relunch job from mirror ring list
 472  *
 473  * @sched: scheduler instance
 474  *
 475  */
 476 void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched)
 477 {
 478         struct drm_sched_job *s_job, *tmp;
 479         uint64_t guilty_context;
 480         bool found_guilty = false;
 481
 482         list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
 483                 struct drm_sched_fence *s_fence = s_job->s_fence;
 484
 485                 if (!found_guilty && atomic_read(&s_job->karma) > sched->hang_limit) {
 486                         found_guilty = true;
 487                         guilty_context = s_job->s_fence->scheduled.context;
 488                 }
 489
 490                 if (found_guilty && s_job->s_fence->scheduled.context == guilty_context)
 491                         dma_fence_set_error(&s_fence->finished, -ECANCELED);
 492
 493                 dma_fence_put(s_job->s_fence->parent);
 494                 s_job->s_fence->parent = sched->ops->run_job(s_job);
 495         }
 496 }
 497 EXPORT_SYMBOL(drm_sched_resubmit_jobs);
 498
 499 /**
 500  * drm_sched_job_init - init a scheduler job
 501  *
 502  * @job: scheduler job to init
 503  * @entity: scheduler entity to use
 504  * @owner: job owner for debugging
 505  *
 506  * Refer to drm_sched_entity_push_job() documentation
 507  * for locking considerations.
 508  *
 509  * Returns 0 for success, negative error code otherwise.
 510  */
 511 int drm_sched_job_init(struct drm_sched_job *job,
 512                        struct drm_sched_entity *entity,
 513                        void *owner)
 514 {
 515         struct drm_gpu_scheduler *sched;
 516
 517         drm_sched_entity_select_rq(entity);
 518         if (!entity->rq)
 519                 return -ENOENT;
 520
 521         sched = entity->rq->sched;
 522
 523         job->sched = sched;
 524         job->entity = entity;
 525         job->s_priority = entity->rq - sched->sched_rq;
 526         job->s_fence = drm_sched_fence_create(entity, owner);
 527         if (!job->s_fence)
 528                 return -ENOMEM;
 529         job->id = atomic64_inc_return(&sched->job_id_count);
 530
 531         INIT_LIST_HEAD(&job->node);
 532
 533         return 0;
 534 }
 535 EXPORT_SYMBOL(drm_sched_job_init);
 536
 537 /**
 538  * drm_sched_job_cleanup - clean up scheduler job resources
 539  *
 540  * @job: scheduler job to clean up
 541  */
 542 void drm_sched_job_cleanup(struct drm_sched_job *job)
 543 {
 544         dma_fence_put(&job->s_fence->finished);
 545         job->s_fence = NULL;
 546 }
 547 EXPORT_SYMBOL(drm_sched_job_cleanup);
 548
 549 /**
 550  * drm_sched_ready - is the scheduler ready
 551  *
 552  * @sched: scheduler instance
 553  *
 554  * Return true if we can push more jobs to the hw, otherwise false.
 555  */
 556 static bool drm_sched_ready(struct drm_gpu_scheduler *sched)
 557 {
 558         return atomic_read(&sched->hw_rq_count) <
 559                 sched->hw_submission_limit;
 560 }
 561
 562 /**
 563  * drm_sched_wakeup - Wake up the scheduler when it is ready
 564  *
 565  * @sched: scheduler instance
 566  *
 567  */
 568 void drm_sched_wakeup(struct drm_gpu_scheduler *sched)
 569 {
 570         if (drm_sched_ready(sched))
 571                 wake_up_interruptible(&sched->wake_up_worker);
 572 }
 573
 574 /**
 575  * drm_sched_select_entity - Select next entity to process
 576  *
 577  * @sched: scheduler instance
 578  *
 579  * Returns the entity to process or NULL if none are found.
 580  */
 581 static struct drm_sched_entity *
 582 drm_sched_select_entity(struct drm_gpu_scheduler *sched)
 583 {
 584         struct drm_sched_entity *entity;
 585         int i;
 586
 587         if (!drm_sched_ready(sched))
 588                 return NULL;
 589
 590         /* Kernel run queue has higher priority than normal run queue*/
 591         for (i = DRM_SCHED_PRIORITY_MAX - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
 592                 entity = drm_sched_rq_select_entity(&sched->sched_rq[i]);
 593                 if (entity)
 594                         break;
 595         }
 596
 597         return entity;
 598 }
 599
 600 /**
 601  * drm_sched_process_job - process a job
 602  *
 603  * @f: fence
 604  * @cb: fence callbacks
 605  *
 606  * Called after job has finished execution.
 607  */
 608 static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
 609 {
 610         struct drm_sched_job *s_job = container_of(cb, struct drm_sched_job, cb);
 611         struct drm_sched_fence *s_fence = s_job->s_fence;
 612         struct drm_gpu_scheduler *sched = s_fence->sched;
 613
 614         atomic_dec(&sched->hw_rq_count);
 615         atomic_dec(&sched->num_jobs);
 616
 617         trace_drm_sched_process_job(s_fence);
 618
 619         drm_sched_fence_finished(s_fence);
 620         wake_up_interruptible(&sched->wake_up_worker);
 621 }
 622
 623 /**
 624  * drm_sched_cleanup_jobs - destroy finished jobs
 625  *
 626  * @sched: scheduler instance
 627  *
 628  * Remove all finished jobs from the mirror list and destroy them.
 629  */
 630 static void drm_sched_cleanup_jobs(struct drm_gpu_scheduler *sched)
 631 {
 632         unsigned long flags;
 633
 634         /* Don't destroy jobs while the timeout worker is running */
 635         if (sched->timeout != MAX_SCHEDULE_TIMEOUT &&
 636             !cancel_delayed_work(&sched->work_tdr))
 637                 return;
 638
 639
 640         while (!list_empty(&sched->ring_mirror_list)) {
 641                 struct drm_sched_job *job;
 642
 643                 job = list_first_entry(&sched->ring_mirror_list,
 644                                        struct drm_sched_job, node);
 645                 if (!dma_fence_is_signaled(&job->s_fence->finished))
 646                         break;
 647
 648                 spin_lock_irqsave(&sched->job_list_lock, flags);
 649                 /* remove job from ring_mirror_list */
 650                 list_del_init(&job->node);
 651                 spin_unlock_irqrestore(&sched->job_list_lock, flags);
 652
 653                 sched->ops->free_job(job);
 654         }
 655
 656         /* queue timeout for next job */
 657         spin_lock_irqsave(&sched->job_list_lock, flags);
 658         drm_sched_start_timeout(sched);
 659         spin_unlock_irqrestore(&sched->job_list_lock, flags);
 660
 661 }
 662
 663 /**
 664  * drm_sched_blocked - check if the scheduler is blocked
 665  *
 666  * @sched: scheduler instance
 667  *
 668  * Returns true if blocked, otherwise false.
 669  */
 670 static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
 671 {
 672         if (kthread_should_park()) {
 673                 kthread_parkme();
 674                 return true;
 675         }
 676
 677         return false;
 678 }
 679
 680 /**
 681  * drm_sched_main - main scheduler thread
 682  *
 683  * @param: scheduler instance
 684  *
 685  * Returns 0.
 686  */
 687 static int drm_sched_main(void *param)
 688 {
 689         struct sched_param sparam = {.sched_priority = 1};
 690         struct drm_gpu_scheduler *sched = (struct drm_gpu_scheduler *)param;
 691         int r;
 692
 693         sched_setscheduler(current, SCHED_FIFO, &sparam);
 694
 695         while (!kthread_should_stop()) {
 696                 struct drm_sched_entity *entity = NULL;
 697                 struct drm_sched_fence *s_fence;
 698                 struct drm_sched_job *sched_job;
 699                 struct dma_fence *fence;
 700
 701                 wait_event_interruptible(sched->wake_up_worker,
 702                                          (drm_sched_cleanup_jobs(sched),
 703                                          (!drm_sched_blocked(sched) &&
 704                                           (entity = drm_sched_select_entity(sched))) ||
 705                                          kthread_should_stop()));
 706
 707                 if (!entity)
 708                         continue;
 709
 710                 sched_job = drm_sched_entity_pop_job(entity);
 711                 if (!sched_job)
 712                         continue;
 713
 714                 s_fence = sched_job->s_fence;
 715
 716                 atomic_inc(&sched->hw_rq_count);
 717                 drm_sched_job_begin(sched_job);
 718
 719                 fence = sched->ops->run_job(sched_job);
 720                 drm_sched_fence_scheduled(s_fence);
 721
 722                 if (fence) {
 723                         s_fence->parent = dma_fence_get(fence);
 724                         r = dma_fence_add_callback(fence, &sched_job->cb,
 725                                                    drm_sched_process_job);
 726                         if (r == -ENOENT)
 727                                 drm_sched_process_job(fence, &sched_job->cb);
 728                         else if (r)
 729                                 DRM_ERROR("fence add callback failed (%d)\n",
 730                                           r);
 731                         dma_fence_put(fence);
 732                 } else
 733                         drm_sched_process_job(NULL, &sched_job->cb);
 734
 735                 wake_up(&sched->job_scheduled);
 736         }
 737         return 0;
 738 }
 739
 740 /**
 741  * drm_sched_init - Init a gpu scheduler instance
 742  *
 743  * @sched: scheduler instance
 744  * @ops: backend operations for this scheduler
 745  * @hw_submission: number of hw submissions that can be in flight
 746  * @hang_limit: number of times to allow a job to hang before dropping it
 747  * @timeout: timeout value in jiffies for the scheduler
 748  * @name: name used for debugging
 749  *
 750  * Return 0 on success, otherwise error code.
 751  */
 752 int drm_sched_init(struct drm_gpu_scheduler *sched,
 753                    const struct drm_sched_backend_ops *ops,
 754                    unsigned hw_submission,
 755                    unsigned hang_limit,
 756                    long timeout,
 757                    const char *name)
 758 {
 759         int i, ret;
 760         sched->ops = ops;
 761         sched->hw_submission_limit = hw_submission;
 762         sched->name = name;
 763         sched->timeout = timeout;
 764         sched->hang_limit = hang_limit;
 765         for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_MAX; i++)
 766                 drm_sched_rq_init(sched, &sched->sched_rq[i]);
 767
 768         init_waitqueue_head(&sched->wake_up_worker);
 769         init_waitqueue_head(&sched->job_scheduled);
 770         INIT_LIST_HEAD(&sched->ring_mirror_list);
 771         spin_lock_init(&sched->job_list_lock);
 772         atomic_set(&sched->hw_rq_count, 0);
 773         INIT_DELAYED_WORK(&sched->work_tdr, drm_sched_job_timedout);
 774         atomic_set(&sched->num_jobs, 0);
 775         atomic64_set(&sched->job_id_count, 0);
 776
 777         /* Each scheduler will run on a seperate kernel thread */
 778         sched->thread = kthread_run(drm_sched_main, sched, sched->name);
 779         if (IS_ERR(sched->thread)) {
 780                 ret = PTR_ERR(sched->thread);
 781                 sched->thread = NULL;
 782                 DRM_ERROR("Failed to create scheduler for %s.\n", name);
 783                 return ret;
 784         }
 785
 786         sched->ready = true;
 787         return 0;
 788 }
 789 EXPORT_SYMBOL(drm_sched_init);
 790
 791 /**
 792  * drm_sched_fini - Destroy a gpu scheduler
 793  *
 794  * @sched: scheduler instance
 795  *
 796  * Tears down and cleans up the scheduler.
 797  */
 798 void drm_sched_fini(struct drm_gpu_scheduler *sched)
 799 {
 800         if (sched->thread)
 801                 kthread_stop(sched->thread);
 802
 803         sched->ready = false;
 804 }
 805 EXPORT_SYMBOL(drm_sched_fini);