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#include <linux/export.h>
25#include <linux/slab.h>
26#include <linux/completion.h>
27
28#include <drm/drm_print.h>
29#include <drm/gpu_scheduler.h>
30
31#include "sched_internal.h"
32
33#include "gpu_scheduler_trace.h"
34
35/**
36 * drm_sched_entity_init - Init a context entity used by scheduler when
37 * submit to HW ring.
38 *
39 * @entity: scheduler entity to init
40 * @priority: priority of the entity
41 * @sched_list: the list of drm scheds on which jobs from this
42 * entity can be submitted
43 * @num_sched_list: number of drm sched in sched_list
44 * @guilty: atomic_t set to 1 when a job on this queue
45 * is found to be guilty causing a timeout
46 *
47 * Note that the &sched_list must have at least one element to schedule the entity.
48 *
49 * For changing @priority later on at runtime see
50 * drm_sched_entity_set_priority(). For changing the set of schedulers
51 * @sched_list at runtime see drm_sched_entity_modify_sched().
52 *
53 * An entity is cleaned up by calling drm_sched_entity_fini(). See also
54 * drm_sched_entity_destroy().
55 *
56 * Returns 0 on success or a negative error code on failure.
57 */
58int drm_sched_entity_init(struct drm_sched_entity *entity,
59 enum drm_sched_priority priority,
60 struct drm_gpu_scheduler **sched_list,
61 unsigned int num_sched_list,
62 atomic_t *guilty)
63{
64 if (!(entity && sched_list && (num_sched_list == 0 || sched_list[0])))
65 return -EINVAL;
66
67 memset(entity, 0, sizeof(struct drm_sched_entity));
68 INIT_LIST_HEAD(list: &entity->list);
69 entity->rq = NULL;
70 entity->guilty = guilty;
71 entity->num_sched_list = num_sched_list;
72 entity->priority = priority;
73 entity->last_user = current->group_leader;
74 /*
75 * It's perfectly valid to initialize an entity without having a valid
76 * scheduler attached. It's just not valid to use the scheduler before it
77 * is initialized itself.
78 */
79 entity->sched_list = num_sched_list > 1 ? sched_list : NULL;
80 RCU_INIT_POINTER(entity->last_scheduled, NULL);
81 RB_CLEAR_NODE(&entity->rb_tree_node);
82
83 if (num_sched_list && !sched_list[0]->sched_rq) {
84 /* Since every entry covered by num_sched_list
85 * should be non-NULL and therefore we warn drivers
86 * not to do this and to fix their DRM calling order.
87 */
88 pr_warn("%s: called with uninitialized scheduler\n", __func__);
89 } else if (num_sched_list) {
90 /* The "priority" of an entity cannot exceed the number of run-queues of a
91 * scheduler. Protect against num_rqs being 0, by converting to signed. Choose
92 * the lowest priority available.
93 */
94 if (entity->priority >= sched_list[0]->num_rqs) {
95 dev_err(sched_list[0]->dev, "entity has out-of-bounds priority: %u. num_rqs: %u\n",
96 entity->priority, sched_list[0]->num_rqs);
97 entity->priority = max_t(s32, (s32) sched_list[0]->num_rqs - 1,
98 (s32) DRM_SCHED_PRIORITY_KERNEL);
99 }
100 entity->rq = sched_list[0]->sched_rq[entity->priority];
101 }
102
103 init_completion(x: &entity->entity_idle);
104
105 /* We start in an idle state. */
106 complete_all(&entity->entity_idle);
107
108 spin_lock_init(&entity->lock);
109 spsc_queue_init(queue: &entity->job_queue);
110
111 atomic_set(v: &entity->fence_seq, i: 0);
112 entity->fence_context = dma_fence_context_alloc(num: 2);
113
114 return 0;
115}
116EXPORT_SYMBOL(drm_sched_entity_init);
117
118/**
119 * drm_sched_entity_modify_sched - Modify sched of an entity
120 * @entity: scheduler entity to init
121 * @sched_list: the list of new drm scheds which will replace
122 * existing entity->sched_list
123 * @num_sched_list: number of drm sched in sched_list
124 *
125 * Note that this must be called under the same common lock for @entity as
126 * drm_sched_job_arm() and drm_sched_entity_push_job(), or the driver needs to
127 * guarantee through some other means that this is never called while new jobs
128 * can be pushed to @entity.
129 */
130void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
131 struct drm_gpu_scheduler **sched_list,
132 unsigned int num_sched_list)
133{
134 WARN_ON(!num_sched_list || !sched_list);
135
136 spin_lock(lock: &entity->lock);
137 entity->sched_list = sched_list;
138 entity->num_sched_list = num_sched_list;
139 spin_unlock(lock: &entity->lock);
140}
141EXPORT_SYMBOL(drm_sched_entity_modify_sched);
142
143static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity)
144{
145 rmb(); /* for list_empty to work without lock */
146
147 if (list_empty(head: &entity->list) ||
148 spsc_queue_count(queue: &entity->job_queue) == 0 ||
149 entity->stopped)
150 return true;
151
152 return false;
153}
154
155/**
156 * drm_sched_entity_error - return error of last scheduled job
157 * @entity: scheduler entity to check
158 *
159 * Opportunistically return the error of the last scheduled job. Result can
160 * change any time when new jobs are pushed to the hw.
161 */
162int drm_sched_entity_error(struct drm_sched_entity *entity)
163{
164 struct dma_fence *fence;
165 int r;
166
167 rcu_read_lock();
168 fence = rcu_dereference(entity->last_scheduled);
169 r = fence ? fence->error : 0;
170 rcu_read_unlock();
171
172 return r;
173}
174EXPORT_SYMBOL(drm_sched_entity_error);
175
176static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
177 struct dma_fence_cb *cb);
178
179static void drm_sched_entity_kill_jobs_work(struct work_struct *wrk)
180{
181 struct drm_sched_job *job = container_of(wrk, typeof(*job), work);
182 struct dma_fence *f;
183 unsigned long index;
184
185 /* Wait for all dependencies to avoid data corruptions */
186 xa_for_each(&job->dependencies, index, f) {
187 struct drm_sched_fence *s_fence = to_drm_sched_fence(f);
188
189 if (s_fence && f == &s_fence->scheduled) {
190 /* The dependencies array had a reference on the scheduled
191 * fence, and the finished fence refcount might have
192 * dropped to zero. Use dma_fence_get_rcu() so we get
193 * a NULL fence in that case.
194 */
195 f = dma_fence_get_rcu(fence: &s_fence->finished);
196
197 /* Now that we have a reference on the finished fence,
198 * we can release the reference the dependencies array
199 * had on the scheduled fence.
200 */
201 dma_fence_put(fence: &s_fence->scheduled);
202 }
203
204 xa_erase(&job->dependencies, index);
205 if (f && !dma_fence_add_callback(fence: f, cb: &job->finish_cb,
206 func: drm_sched_entity_kill_jobs_cb))
207 return;
208
209 dma_fence_put(fence: f);
210 }
211
212 drm_sched_fence_scheduled(fence: job->s_fence, NULL);
213 drm_sched_fence_finished(fence: job->s_fence, result: -ESRCH);
214 WARN_ON(job->s_fence->parent);
215 job->sched->ops->free_job(job);
216}
217
218/* Signal the scheduler finished fence when the entity in question is killed. */
219static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
220 struct dma_fence_cb *cb)
221{
222 struct drm_sched_job *job = container_of(cb, struct drm_sched_job,
223 finish_cb);
224
225 dma_fence_put(fence: f);
226
227 INIT_WORK(&job->work, drm_sched_entity_kill_jobs_work);
228 schedule_work(work: &job->work);
229}
230
231/* Remove the entity from the scheduler and kill all pending jobs */
232static void drm_sched_entity_kill(struct drm_sched_entity *entity)
233{
234 struct drm_sched_job *job;
235 struct dma_fence *prev;
236
237 if (!entity->rq)
238 return;
239
240 spin_lock(lock: &entity->lock);
241 entity->stopped = true;
242 drm_sched_rq_remove_entity(rq: entity->rq, entity);
243 spin_unlock(lock: &entity->lock);
244
245 /* Make sure this entity is not used by the scheduler at the moment */
246 wait_for_completion(&entity->entity_idle);
247
248 /* The entity is guaranteed to not be used by the scheduler */
249 prev = rcu_dereference_check(entity->last_scheduled, true);
250 dma_fence_get(fence: prev);
251 while ((job = drm_sched_entity_queue_pop(entity))) {
252 struct drm_sched_fence *s_fence = job->s_fence;
253
254 dma_fence_get(fence: &s_fence->finished);
255 if (!prev ||
256 dma_fence_add_callback(fence: prev, cb: &job->finish_cb,
257 func: drm_sched_entity_kill_jobs_cb)) {
258 /*
259 * Adding callback above failed.
260 * dma_fence_put() checks for NULL.
261 */
262 dma_fence_put(fence: prev);
263 drm_sched_entity_kill_jobs_cb(NULL, cb: &job->finish_cb);
264 }
265
266 prev = &s_fence->finished;
267 }
268 dma_fence_put(fence: prev);
269}
270
271/**
272 * drm_sched_entity_flush - Flush a context entity
273 *
274 * @entity: scheduler entity
275 * @timeout: time to wait in for Q to become empty in jiffies.
276 *
277 * Splitting drm_sched_entity_fini() into two functions, The first one does the
278 * waiting, removes the entity from the runqueue and returns an error when the
279 * process was killed.
280 *
281 * Returns the remaining time in jiffies left from the input timeout
282 */
283long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
284{
285 struct drm_gpu_scheduler *sched;
286 struct task_struct *last_user;
287 long ret = timeout;
288
289 if (!entity->rq)
290 return 0;
291
292 sched = entity->rq->sched;
293 /*
294 * The client will not queue more jobs during this fini - consume
295 * existing queued ones, or discard them on SIGKILL.
296 */
297 if (current->flags & PF_EXITING) {
298 if (timeout)
299 ret = wait_event_timeout(
300 sched->job_scheduled,
301 drm_sched_entity_is_idle(entity),
302 timeout);
303 } else {
304 wait_event_killable(sched->job_scheduled,
305 drm_sched_entity_is_idle(entity));
306 }
307
308 /* For a killed process disallow further enqueueing of jobs. */
309 last_user = cmpxchg(&entity->last_user, current->group_leader, NULL);
310 if (last_user == current->group_leader &&
311 (current->flags & PF_EXITING) && (current->exit_code == SIGKILL))
312 drm_sched_entity_kill(entity);
313
314 return ret;
315}
316EXPORT_SYMBOL(drm_sched_entity_flush);
317
318/**
319 * drm_sched_entity_fini - Destroy a context entity
320 *
321 * @entity: scheduler entity
322 *
323 * Cleanups up @entity which has been initialized by drm_sched_entity_init().
324 *
325 * If there are potentially job still in flight or getting newly queued
326 * drm_sched_entity_flush() must be called first. This function then goes over
327 * the entity and signals all jobs with an error code if the process was killed.
328 */
329void drm_sched_entity_fini(struct drm_sched_entity *entity)
330{
331 /*
332 * If consumption of existing jobs wasn't completed forcefully remove
333 * them. Also makes sure that the scheduler won't touch this entity any
334 * more.
335 */
336 drm_sched_entity_kill(entity);
337
338 if (entity->dependency) {
339 dma_fence_remove_callback(fence: entity->dependency, cb: &entity->cb);
340 dma_fence_put(fence: entity->dependency);
341 entity->dependency = NULL;
342 }
343
344 dma_fence_put(rcu_dereference_check(entity->last_scheduled, true));
345 RCU_INIT_POINTER(entity->last_scheduled, NULL);
346}
347EXPORT_SYMBOL(drm_sched_entity_fini);
348
349/**
350 * drm_sched_entity_destroy - Destroy a context entity
351 * @entity: scheduler entity
352 *
353 * Calls drm_sched_entity_flush() and drm_sched_entity_fini() as a
354 * convenience wrapper.
355 */
356void drm_sched_entity_destroy(struct drm_sched_entity *entity)
357{
358 drm_sched_entity_flush(entity, MAX_WAIT_SCHED_ENTITY_Q_EMPTY);
359 drm_sched_entity_fini(entity);
360}
361EXPORT_SYMBOL(drm_sched_entity_destroy);
362
363/*
364 * drm_sched_entity_wakeup - callback to clear the entity's dependency and
365 * wake up the scheduler
366 */
367static void drm_sched_entity_wakeup(struct dma_fence *f,
368 struct dma_fence_cb *cb)
369{
370 struct drm_sched_entity *entity =
371 container_of(cb, struct drm_sched_entity, cb);
372
373 entity->dependency = NULL;
374 dma_fence_put(fence: f);
375 drm_sched_wakeup(sched: entity->rq->sched);
376}
377
378/**
379 * drm_sched_entity_set_priority - Sets priority of the entity
380 *
381 * @entity: scheduler entity
382 * @priority: scheduler priority
383 *
384 * Update the priority of runqueues used for the entity.
385 */
386void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
387 enum drm_sched_priority priority)
388{
389 spin_lock(lock: &entity->lock);
390 entity->priority = priority;
391 spin_unlock(lock: &entity->lock);
392}
393EXPORT_SYMBOL(drm_sched_entity_set_priority);
394
395/*
396 * Add a callback to the current dependency of the entity to wake up the
397 * scheduler when the entity becomes available.
398 */
399static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity,
400 struct drm_sched_job *sched_job)
401{
402 struct drm_gpu_scheduler *sched = entity->rq->sched;
403 struct dma_fence *fence = entity->dependency;
404 struct drm_sched_fence *s_fence;
405
406 if (fence->context == entity->fence_context ||
407 fence->context == entity->fence_context + 1) {
408 /*
409 * Fence is a scheduled/finished fence from a job
410 * which belongs to the same entity, we can ignore
411 * fences from ourself
412 */
413 dma_fence_put(fence: entity->dependency);
414 return false;
415 }
416
417 s_fence = to_drm_sched_fence(f: fence);
418 if (!fence->error && s_fence && s_fence->sched == sched &&
419 !test_bit(DRM_SCHED_FENCE_DONT_PIPELINE, &fence->flags)) {
420
421 /*
422 * Fence is from the same scheduler, only need to wait for
423 * it to be scheduled
424 */
425 fence = dma_fence_get(fence: &s_fence->scheduled);
426 dma_fence_put(fence: entity->dependency);
427 entity->dependency = fence;
428 }
429
430 if (trace_drm_sched_job_unschedulable_enabled() &&
431 !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &entity->dependency->flags))
432 trace_drm_sched_job_unschedulable(sched_job, fence: entity->dependency);
433
434 if (!dma_fence_add_callback(fence: entity->dependency, cb: &entity->cb,
435 func: drm_sched_entity_wakeup))
436 return true;
437
438 dma_fence_put(fence: entity->dependency);
439 return false;
440}
441
442static struct dma_fence *
443drm_sched_job_dependency(struct drm_sched_job *job,
444 struct drm_sched_entity *entity)
445{
446 struct dma_fence *f;
447
448 /* We keep the fence around, so we can iterate over all dependencies
449 * in drm_sched_entity_kill_jobs_cb() to ensure all deps are signaled
450 * before killing the job.
451 */
452 f = xa_load(&job->dependencies, index: job->last_dependency);
453 if (f) {
454 job->last_dependency++;
455 return dma_fence_get(fence: f);
456 }
457
458 if (job->sched->ops->prepare_job)
459 return job->sched->ops->prepare_job(job, entity);
460
461 return NULL;
462}
463
464struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
465{
466 struct drm_sched_job *sched_job;
467
468 sched_job = drm_sched_entity_queue_peek(entity);
469 if (!sched_job)
470 return NULL;
471
472 while ((entity->dependency =
473 drm_sched_job_dependency(job: sched_job, entity))) {
474 if (drm_sched_entity_add_dependency_cb(entity, sched_job))
475 return NULL;
476 }
477
478 /* skip jobs from entity that marked guilty */
479 if (entity->guilty && atomic_read(v: entity->guilty))
480 dma_fence_set_error(fence: &sched_job->s_fence->finished, error: -ECANCELED);
481
482 dma_fence_put(rcu_dereference_check(entity->last_scheduled, true));
483 rcu_assign_pointer(entity->last_scheduled,
484 dma_fence_get(&sched_job->s_fence->finished));
485
486 /*
487 * If the queue is empty we allow drm_sched_entity_select_rq() to
488 * locklessly access ->last_scheduled. This only works if we set the
489 * pointer before we dequeue and if we a write barrier here.
490 */
491 smp_wmb();
492
493 spsc_queue_pop(queue: &entity->job_queue);
494
495 /*
496 * Update the entity's location in the min heap according to
497 * the timestamp of the next job, if any.
498 */
499 if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) {
500 struct drm_sched_job *next;
501
502 next = drm_sched_entity_queue_peek(entity);
503 if (next) {
504 struct drm_sched_rq *rq;
505
506 spin_lock(lock: &entity->lock);
507 rq = entity->rq;
508 spin_lock(lock: &rq->lock);
509 drm_sched_rq_update_fifo_locked(entity, rq,
510 ts: next->submit_ts);
511 spin_unlock(lock: &rq->lock);
512 spin_unlock(lock: &entity->lock);
513 }
514 }
515
516 /* Jobs and entities might have different lifecycles. Since we're
517 * removing the job from the entities queue, set the jobs entity pointer
518 * to NULL to prevent any future access of the entity through this job.
519 */
520 sched_job->entity = NULL;
521
522 return sched_job;
523}
524
525void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
526{
527 struct dma_fence *fence;
528 struct drm_gpu_scheduler *sched;
529 struct drm_sched_rq *rq;
530
531 /* single possible engine and already selected */
532 if (!entity->sched_list)
533 return;
534
535 /* queue non-empty, stay on the same engine */
536 if (spsc_queue_count(queue: &entity->job_queue))
537 return;
538
539 /*
540 * Only when the queue is empty are we guaranteed that
541 * drm_sched_run_job_work() cannot change entity->last_scheduled. To
542 * enforce ordering we need a read barrier here. See
543 * drm_sched_entity_pop_job() for the other side.
544 */
545 smp_rmb();
546
547 fence = rcu_dereference_check(entity->last_scheduled, true);
548
549 /* stay on the same engine if the previous job hasn't finished */
550 if (fence && !dma_fence_is_signaled(fence))
551 return;
552
553 spin_lock(lock: &entity->lock);
554 sched = drm_sched_pick_best(sched_list: entity->sched_list, num_sched_list: entity->num_sched_list);
555 rq = sched ? sched->sched_rq[entity->priority] : NULL;
556 if (rq != entity->rq) {
557 drm_sched_rq_remove_entity(rq: entity->rq, entity);
558 entity->rq = rq;
559 }
560
561 if (entity->num_sched_list == 1)
562 entity->sched_list = NULL;
563
564 spin_unlock(lock: &entity->lock);
565}
566
567/**
568 * drm_sched_entity_push_job - Submit a job to the entity's job queue
569 * @sched_job: job to submit
570 *
571 * Note: To guarantee that the order of insertion to queue matches the job's
572 * fence sequence number this function should be called with drm_sched_job_arm()
573 * under common lock for the struct drm_sched_entity that was set up for
574 * @sched_job in drm_sched_job_init().
575 */
576void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
577{
578 struct drm_sched_entity *entity = sched_job->entity;
579 bool first;
580 ktime_t submit_ts;
581
582 trace_drm_sched_job_queue(sched_job, entity);
583
584 if (trace_drm_sched_job_add_dep_enabled()) {
585 struct dma_fence *entry;
586 unsigned long index;
587
588 xa_for_each(&sched_job->dependencies, index, entry)
589 trace_drm_sched_job_add_dep(sched_job, fence: entry);
590 }
591 atomic_inc(v: entity->rq->sched->score);
592 WRITE_ONCE(entity->last_user, current->group_leader);
593
594 /*
595 * After the sched_job is pushed into the entity queue, it may be
596 * completed and freed up at any time. We can no longer access it.
597 * Make sure to set the submit_ts first, to avoid a race.
598 */
599 sched_job->submit_ts = submit_ts = ktime_get();
600 first = spsc_queue_push(queue: &entity->job_queue, node: &sched_job->queue_node);
601
602 /* first job wakes up scheduler */
603 if (first) {
604 struct drm_gpu_scheduler *sched;
605 struct drm_sched_rq *rq;
606
607 /* Add the entity to the run queue */
608 spin_lock(lock: &entity->lock);
609 if (entity->stopped) {
610 spin_unlock(lock: &entity->lock);
611
612 DRM_ERROR("Trying to push to a killed entity\n");
613 return;
614 }
615
616 rq = entity->rq;
617 sched = rq->sched;
618
619 spin_lock(lock: &rq->lock);
620 drm_sched_rq_add_entity(rq, entity);
621
622 if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
623 drm_sched_rq_update_fifo_locked(entity, rq, ts: submit_ts);
624
625 spin_unlock(lock: &rq->lock);
626 spin_unlock(lock: &entity->lock);
627
628 drm_sched_wakeup(sched);
629 }
630}
631EXPORT_SYMBOL(drm_sched_entity_push_job);
632

source code of linux/drivers/gpu/drm/scheduler/sched_entity.c