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         spin_lock_irqsave(&sched->job_list_lock, flags);
 302         drm_sched_start_timeout(sched);
 303         spin_unlock_irqrestore(&sched->job_list_lock, flags);
 304 }
 305
 306  /**
 307   * drm_sched_increase_karma - Update sched_entity guilty flag
 308   *
 309   * @bad: The job guilty of time out
 310   *
 311   * Increment on every hang caused by the 'bad' job. If this exceeds the hang
 312   * limit of the scheduler then the respective sched entity is marked guilty and
 313   * jobs from it will not be scheduled further
 314   */
 315 void drm_sched_increase_karma(struct drm_sched_job *bad)
 316 {
 317         int i;
 318         struct drm_sched_entity *tmp;
 319         struct drm_sched_entity *entity;
 320         struct drm_gpu_scheduler *sched = bad->sched;
 321
 322         /* don't increase @bad's karma if it's from KERNEL RQ,
 323          * because sometimes GPU hang would cause kernel jobs (like VM updating jobs)
 324          * corrupt but keep in mind that kernel jobs always considered good.
 325          */
 326         if (bad->s_priority != DRM_SCHED_PRIORITY_KERNEL) {
 327                 atomic_inc(&bad->karma);
 328                 for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_KERNEL;
 329                      i++) {
 330                         struct drm_sched_rq *rq = &sched->sched_rq[i];
 331
 332                         spin_lock(&rq->lock);
 333                         list_for_each_entry_safe(entity, tmp, &rq->entities, list) {
 334                                 if (bad->s_fence->scheduled.context ==
 335                                     entity->fence_context) {
 336                                         if (atomic_read(&bad->karma) >
 337                                             bad->sched->hang_limit)
 338                                                 if (entity->guilty)
 339                                                         atomic_set(entity->guilty, 1);
 340                                         break;
 341                                 }
 342                         }
 343                         spin_unlock(&rq->lock);
 344                         if (&entity->list != &rq->entities)
 345                                 break;
 346                 }
 347         }
 348 }
 349 EXPORT_SYMBOL(drm_sched_increase_karma);
 350
 351 /**
 352  * drm_sched_hw_job_reset - stop the scheduler if it contains the bad job
 353  *
 354  * @sched: scheduler instance
 355  * @bad: bad scheduler job
 356  *
 357  * Stop the scheduler and also removes and frees all completed jobs.
 358  * Note: bad job will not be freed as it might be used later and so it's
 359  * callers responsibility to release it manually if it's not part of the
 360  * mirror list any more.
 361  *
 362  */
 363 void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
 364 {
 365         struct drm_sched_job *s_job, *tmp;
 366         unsigned long flags;
 367
 368         kthread_park(sched->thread);
 369
 370         /*
 371          * Iterate the job list from later to  earlier one and either deactive
 372          * their HW callbacks or remove them from mirror list if they already
 373          * signaled.
 374          * This iteration is thread safe as sched thread is stopped.
 375          */
 376         list_for_each_entry_safe_reverse(s_job, tmp, &sched->ring_mirror_list, node) {
 377                 if (s_job->s_fence->parent &&
 378                     dma_fence_remove_callback(s_job->s_fence->parent,
 379                                               &s_job->cb)) {
 380                         atomic_dec(&sched->hw_rq_count);
 381                 } else {
 382                         /*
 383                          * remove job from ring_mirror_list.
 384                          * Locking here is for concurrent resume timeout
 385                          */
 386                         spin_lock_irqsave(&sched->job_list_lock, flags);
 387                         list_del_init(&s_job->node);
 388                         spin_unlock_irqrestore(&sched->job_list_lock, flags);
 389
 390                         /*
 391                          * Wait for job's HW fence callback to finish using s_job
 392                          * before releasing it.
 393                          *
 394                          * Job is still alive so fence refcount at least 1
 395                          */
 396                         dma_fence_wait(&s_job->s_fence->finished, false);
 397
 398                         /*
 399                          * We must keep bad job alive for later use during
 400                          * recovery by some of the drivers but leave a hint
 401                          * that the guilty job must be released.
 402                          */
 403                         if (bad != s_job)
 404                                 sched->ops->free_job(s_job);
 405                         else
 406                                 sched->free_guilty = true;
 407                 }
 408         }
 409
 410         /*
 411          * Stop pending timer in flight as we rearm it in  drm_sched_start. This
 412          * avoids the pending timeout work in progress to fire right away after
 413          * this TDR finished and before the newly restarted jobs had a
 414          * chance to complete.
 415          */
 416         cancel_delayed_work(&sched->work_tdr);
 417 }
 418
 419 EXPORT_SYMBOL(drm_sched_stop);
 420
 421 /**
 422  * drm_sched_job_recovery - recover jobs after a reset
 423  *
 424  * @sched: scheduler instance
 425  *
 426  */
 427 void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
 428 {
 429         struct drm_sched_job *s_job, *tmp;
 430         unsigned long flags;
 431         int r;
 432
 433         /*
 434          * Locking the list is not required here as the sched thread is parked
 435          * so no new jobs are being inserted or removed. Also concurrent
 436          * GPU recovers can't run in parallel.
 437          */
 438         list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
 439                 struct dma_fence *fence = s_job->s_fence->parent;
 440
 441                 atomic_inc(&sched->hw_rq_count);
 442
 443                 if (!full_recovery)
 444                         continue;
 445
 446                 if (fence) {
 447                         r = dma_fence_add_callback(fence, &s_job->cb,
 448                                                    drm_sched_process_job);
 449                         if (r == -ENOENT)
 450                                 drm_sched_process_job(fence, &s_job->cb);
 451                         else if (r)
 452                                 DRM_ERROR("fence add callback failed (%d)\n",
 453                                           r);
 454                 } else
 455                         drm_sched_process_job(NULL, &s_job->cb);
 456         }
 457
 458         if (full_recovery) {
 459                 spin_lock_irqsave(&sched->job_list_lock, flags);
 460                 drm_sched_start_timeout(sched);
 461                 spin_unlock_irqrestore(&sched->job_list_lock, flags);
 462         }
 463
 464         kthread_unpark(sched->thread);
 465 }
 466 EXPORT_SYMBOL(drm_sched_start);
 467
 468 /**
 469  * drm_sched_resubmit_jobs - helper to relunch job from mirror ring list
 470  *
 471  * @sched: scheduler instance
 472  *
 473  */
 474 void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched)
 475 {
 476         struct drm_sched_job *s_job, *tmp;
 477         uint64_t guilty_context;
 478         bool found_guilty = false;
 479
 480         list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
 481                 struct drm_sched_fence *s_fence = s_job->s_fence;
 482
 483                 if (!found_guilty && atomic_read(&s_job->karma) > sched->hang_limit) {
 484                         found_guilty = true;
 485                         guilty_context = s_job->s_fence->scheduled.context;
 486                 }
 487
 488                 if (found_guilty && s_job->s_fence->scheduled.context == guilty_context)
 489                         dma_fence_set_error(&s_fence->finished, -ECANCELED);
 490
 491                 dma_fence_put(s_job->s_fence->parent);
 492                 s_job->s_fence->parent = sched->ops->run_job(s_job);
 493         }
 494 }
 495 EXPORT_SYMBOL(drm_sched_resubmit_jobs);
 496
 497 /**
 498  * drm_sched_job_init - init a scheduler job
 499  *
 500  * @job: scheduler job to init
 501  * @entity: scheduler entity to use
 502  * @owner: job owner for debugging
 503  *
 504  * Refer to drm_sched_entity_push_job() documentation
 505  * for locking considerations.
 506  *
 507  * Returns 0 for success, negative error code otherwise.
 508  */
 509 int drm_sched_job_init(struct drm_sched_job *job,
 510                        struct drm_sched_entity *entity,
 511                        void *owner)
 512 {
 513         struct drm_gpu_scheduler *sched;
 514
 515         drm_sched_entity_select_rq(entity);
 516         if (!entity->rq)
 517                 return -ENOENT;
 518
 519         sched = entity->rq->sched;
 520
 521         job->sched = sched;
 522         job->entity = entity;
 523         job->s_priority = entity->rq - sched->sched_rq;
 524         job->s_fence = drm_sched_fence_create(entity, owner);
 525         if (!job->s_fence)
 526                 return -ENOMEM;
 527         job->id = atomic64_inc_return(&sched->job_id_count);
 528
 529         INIT_LIST_HEAD(&job->node);
 530
 531         return 0;
 532 }
 533 EXPORT_SYMBOL(drm_sched_job_init);
 534
 535 /**
 536  * drm_sched_job_cleanup - clean up scheduler job resources
 537  *
 538  * @job: scheduler job to clean up
 539  */
 540 void drm_sched_job_cleanup(struct drm_sched_job *job)
 541 {
 542         dma_fence_put(&job->s_fence->finished);
 543         job->s_fence = NULL;
 544 }
 545 EXPORT_SYMBOL(drm_sched_job_cleanup);
 546
 547 /**
 548  * drm_sched_ready - is the scheduler ready
 549  *
 550  * @sched: scheduler instance
 551  *
 552  * Return true if we can push more jobs to the hw, otherwise false.
 553  */
 554 static bool drm_sched_ready(struct drm_gpu_scheduler *sched)
 555 {
 556         return atomic_read(&sched->hw_rq_count) <
 557                 sched->hw_submission_limit;
 558 }
 559
 560 /**
 561  * drm_sched_wakeup - Wake up the scheduler when it is ready
 562  *
 563  * @sched: scheduler instance
 564  *
 565  */
 566 void drm_sched_wakeup(struct drm_gpu_scheduler *sched)
 567 {
 568         if (drm_sched_ready(sched))
 569                 wake_up_interruptible(&sched->wake_up_worker);
 570 }
 571
 572 /**
 573  * drm_sched_select_entity - Select next entity to process
 574  *
 575  * @sched: scheduler instance
 576  *
 577  * Returns the entity to process or NULL if none are found.
 578  */
 579 static struct drm_sched_entity *
 580 drm_sched_select_entity(struct drm_gpu_scheduler *sched)
 581 {
 582         struct drm_sched_entity *entity;
 583         int i;
 584
 585         if (!drm_sched_ready(sched))
 586                 return NULL;
 587
 588         /* Kernel run queue has higher priority than normal run queue*/
 589         for (i = DRM_SCHED_PRIORITY_MAX - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
 590                 entity = drm_sched_rq_select_entity(&sched->sched_rq[i]);
 591                 if (entity)
 592                         break;
 593         }
 594
 595         return entity;
 596 }
 597
 598 /**
 599  * drm_sched_process_job - process a job
 600  *
 601  * @f: fence
 602  * @cb: fence callbacks
 603  *
 604  * Called after job has finished execution.
 605  */
 606 static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
 607 {
 608         struct drm_sched_job *s_job = container_of(cb, struct drm_sched_job, cb);
 609         struct drm_sched_fence *s_fence = s_job->s_fence;
 610         struct drm_gpu_scheduler *sched = s_fence->sched;
 611
 612         atomic_dec(&sched->hw_rq_count);
 613         atomic_dec(&sched->num_jobs);
 614
 615         trace_drm_sched_process_job(s_fence);
 616
 617         drm_sched_fence_finished(s_fence);
 618         wake_up_interruptible(&sched->wake_up_worker);
 619 }
 620
 621 /**
 622  * drm_sched_cleanup_jobs - destroy finished jobs
 623  *
 624  * @sched: scheduler instance
 625  *
 626  * Remove all finished jobs from the mirror list and destroy them.
 627  */
 628 static void drm_sched_cleanup_jobs(struct drm_gpu_scheduler *sched)
 629 {
 630         unsigned long flags;
 631
 632         /* Don't destroy jobs while the timeout worker is running */
 633         if (!cancel_delayed_work(&sched->work_tdr))
 634                 return;
 635
 636
 637         while (!list_empty(&sched->ring_mirror_list)) {
 638                 struct drm_sched_job *job;
 639
 640                 job = list_first_entry(&sched->ring_mirror_list,
 641                                        struct drm_sched_job, node);
 642                 if (!dma_fence_is_signaled(&job->s_fence->finished))
 643                         break;
 644
 645                 spin_lock_irqsave(&sched->job_list_lock, flags);
 646                 /* remove job from ring_mirror_list */
 647                 list_del_init(&job->node);
 648                 spin_unlock_irqrestore(&sched->job_list_lock, flags);
 649
 650                 sched->ops->free_job(job);
 651         }
 652
 653         /* queue timeout for next job */
 654         spin_lock_irqsave(&sched->job_list_lock, flags);
 655         drm_sched_start_timeout(sched);
 656         spin_unlock_irqrestore(&sched->job_list_lock, flags);
 657
 658 }
 659
 660 /**
 661  * drm_sched_blocked - check if the scheduler is blocked
 662  *
 663  * @sched: scheduler instance
 664  *
 665  * Returns true if blocked, otherwise false.
 666  */
 667 static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
 668 {
 669         if (kthread_should_park()) {
 670                 kthread_parkme();
 671                 return true;
 672         }
 673
 674         return false;
 675 }
 676
 677 /**
 678  * drm_sched_main - main scheduler thread
 679  *
 680  * @param: scheduler instance
 681  *
 682  * Returns 0.
 683  */
 684 static int drm_sched_main(void *param)
 685 {
 686         struct sched_param sparam = {.sched_priority = 1};
 687         struct drm_gpu_scheduler *sched = (struct drm_gpu_scheduler *)param;
 688         int r;
 689
 690         sched_setscheduler(current, SCHED_FIFO, &sparam);
 691
 692         while (!kthread_should_stop()) {
 693                 struct drm_sched_entity *entity = NULL;
 694                 struct drm_sched_fence *s_fence;
 695                 struct drm_sched_job *sched_job;
 696                 struct dma_fence *fence;
 697
 698                 wait_event_interruptible(sched->wake_up_worker,
 699                                          (drm_sched_cleanup_jobs(sched),
 700                                          (!drm_sched_blocked(sched) &&
 701                                           (entity = drm_sched_select_entity(sched))) ||
 702                                          kthread_should_stop()));
 703
 704                 if (!entity)
 705                         continue;
 706
 707                 sched_job = drm_sched_entity_pop_job(entity);
 708                 if (!sched_job)
 709                         continue;
 710
 711                 s_fence = sched_job->s_fence;
 712
 713                 atomic_inc(&sched->hw_rq_count);
 714                 drm_sched_job_begin(sched_job);
 715
 716                 fence = sched->ops->run_job(sched_job);
 717                 drm_sched_fence_scheduled(s_fence);
 718
 719                 if (fence) {
 720                         s_fence->parent = dma_fence_get(fence);
 721                         r = dma_fence_add_callback(fence, &sched_job->cb,
 722                                                    drm_sched_process_job);
 723                         if (r == -ENOENT)
 724                                 drm_sched_process_job(fence, &sched_job->cb);
 725                         else if (r)
 726                                 DRM_ERROR("fence add callback failed (%d)\n",
 727                                           r);
 728                         dma_fence_put(fence);
 729                 } else
 730                         drm_sched_process_job(NULL, &sched_job->cb);
 731
 732                 wake_up(&sched->job_scheduled);
 733         }
 734         return 0;
 735 }
 736
 737 /**
 738  * drm_sched_init - Init a gpu scheduler instance
 739  *
 740  * @sched: scheduler instance
 741  * @ops: backend operations for this scheduler
 742  * @hw_submission: number of hw submissions that can be in flight
 743  * @hang_limit: number of times to allow a job to hang before dropping it
 744  * @timeout: timeout value in jiffies for the scheduler
 745  * @name: name used for debugging
 746  *
 747  * Return 0 on success, otherwise error code.
 748  */
 749 int drm_sched_init(struct drm_gpu_scheduler *sched,
 750                    const struct drm_sched_backend_ops *ops,
 751                    unsigned hw_submission,
 752                    unsigned hang_limit,
 753                    long timeout,
 754                    const char *name)
 755 {
 756         int i, ret;
 757         sched->ops = ops;
 758         sched->hw_submission_limit = hw_submission;
 759         sched->name = name;
 760         sched->timeout = timeout;
 761         sched->hang_limit = hang_limit;
 762         for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_MAX; i++)
 763                 drm_sched_rq_init(sched, &sched->sched_rq[i]);
 764
 765         init_waitqueue_head(&sched->wake_up_worker);
 766         init_waitqueue_head(&sched->job_scheduled);
 767         INIT_LIST_HEAD(&sched->ring_mirror_list);
 768         spin_lock_init(&sched->job_list_lock);
 769         atomic_set(&sched->hw_rq_count, 0);
 770         INIT_DELAYED_WORK(&sched->work_tdr, drm_sched_job_timedout);
 771         atomic_set(&sched->num_jobs, 0);
 772         atomic64_set(&sched->job_id_count, 0);
 773
 774         /* Each scheduler will run on a seperate kernel thread */
 775         sched->thread = kthread_run(drm_sched_main, sched, sched->name);
 776         if (IS_ERR(sched->thread)) {
 777                 ret = PTR_ERR(sched->thread);
 778                 sched->thread = NULL;
 779                 DRM_ERROR("Failed to create scheduler for %s.\n", name);
 780                 return ret;
 781         }
 782
 783         sched->ready = true;
 784         return 0;
 785 }
 786 EXPORT_SYMBOL(drm_sched_init);
 787
 788 /**
 789  * drm_sched_fini - Destroy a gpu scheduler
 790  *
 791  * @sched: scheduler instance
 792  *
 793  * Tears down and cleans up the scheduler.
 794  */
 795 void drm_sched_fini(struct drm_gpu_scheduler *sched)
 796 {
 797         if (sched->thread)
 798                 kthread_stop(sched->thread);
 799
 800         sched->ready = false;
 801 }
 802 EXPORT_SYMBOL(drm_sched_fini);