summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/scheduler/sched_entity.c
blob: a75eede8bf8dabd235b1fe1905c860ebaa78f384 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
/*
 * Copyright 2015 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include <linux/kthread.h>
#include <linux/slab.h>
#include <linux/completion.h>

#include <drm/drm_print.h>
#include <drm/gpu_scheduler.h>

#include "gpu_scheduler_trace.h"

#define to_drm_sched_job(sched_job)		\
		container_of((sched_job), struct drm_sched_job, queue_node)

/**
 * drm_sched_entity_init - Init a context entity used by scheduler when
 * submit to HW ring.
 *
 * @entity: scheduler entity to init
 * @priority: priority of the entity
 * @sched_list: the list of drm scheds on which jobs from this
 *           entity can be submitted
 * @num_sched_list: number of drm sched in sched_list
 * @guilty: atomic_t set to 1 when a job on this queue
 *          is found to be guilty causing a timeout
 *
 * Note that the &sched_list must have at least one element to schedule the entity.
 *
 * For changing @priority later on at runtime see
 * drm_sched_entity_set_priority(). For changing the set of schedulers
 * @sched_list at runtime see drm_sched_entity_modify_sched().
 *
 * An entity is cleaned up by callind drm_sched_entity_fini(). See also
 * drm_sched_entity_destroy().
 *
 * Returns 0 on success or a negative error code on failure.
 */
int drm_sched_entity_init(struct drm_sched_entity *entity,
			  enum drm_sched_priority priority,
			  struct drm_gpu_scheduler **sched_list,
			  unsigned int num_sched_list,
			  atomic_t *guilty)
{
	if (!(entity && sched_list && (num_sched_list == 0 || sched_list[0])))
		return -EINVAL;

	memset(entity, 0, sizeof(struct drm_sched_entity));
	INIT_LIST_HEAD(&entity->list);
	entity->rq = NULL;
	entity->guilty = guilty;
	entity->num_sched_list = num_sched_list;
	entity->priority = priority;
	/*
	 * It's perfectly valid to initialize an entity without having a valid
	 * scheduler attached. It's just not valid to use the scheduler before it
	 * is initialized itself.
	 */
	entity->sched_list = num_sched_list > 1 ? sched_list : NULL;
	RCU_INIT_POINTER(entity->last_scheduled, NULL);
	RB_CLEAR_NODE(&entity->rb_tree_node);

	if (num_sched_list && !sched_list[0]->sched_rq) {
		/* Since every entry covered by num_sched_list
		 * should be non-NULL and therefore we warn drivers
		 * not to do this and to fix their DRM calling order.
		 */
		pr_warn("%s: called with uninitialized scheduler\n", __func__);
	} else if (num_sched_list) {
		/* The "priority" of an entity cannot exceed the number of run-queues of a
		 * scheduler. Protect against num_rqs being 0, by converting to signed. Choose
		 * the lowest priority available.
		 */
		if (entity->priority >= sched_list[0]->num_rqs) {
			drm_err(sched_list[0], "entity with out-of-bounds priority:%u num_rqs:%u\n",
				entity->priority, sched_list[0]->num_rqs);
			entity->priority = max_t(s32, (s32) sched_list[0]->num_rqs - 1,
						 (s32) DRM_SCHED_PRIORITY_KERNEL);
		}
		entity->rq = sched_list[0]->sched_rq[entity->priority];
	}

	init_completion(&entity->entity_idle);

	/* We start in an idle state. */
	complete_all(&entity->entity_idle);

	spin_lock_init(&entity->rq_lock);
	spsc_queue_init(&entity->job_queue);

	atomic_set(&entity->fence_seq, 0);
	entity->fence_context = dma_fence_context_alloc(2);

	return 0;
}
EXPORT_SYMBOL(drm_sched_entity_init);

/**
 * drm_sched_entity_modify_sched - Modify sched of an entity
 * @entity: scheduler entity to init
 * @sched_list: the list of new drm scheds which will replace
 *		 existing entity->sched_list
 * @num_sched_list: number of drm sched in sched_list
 *
 * Note that this must be called under the same common lock for @entity as
 * drm_sched_job_arm() and drm_sched_entity_push_job(), or the driver needs to
 * guarantee through some other means that this is never called while new jobs
 * can be pushed to @entity.
 */
void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
				    struct drm_gpu_scheduler **sched_list,
				    unsigned int num_sched_list)
{
	WARN_ON(!num_sched_list || !sched_list);

	spin_lock(&entity->rq_lock);
	entity->sched_list = sched_list;
	entity->num_sched_list = num_sched_list;
	spin_unlock(&entity->rq_lock);
}
EXPORT_SYMBOL(drm_sched_entity_modify_sched);

static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity)
{
	rmb(); /* for list_empty to work without lock */

	if (list_empty(&entity->list) ||
	    spsc_queue_count(&entity->job_queue) == 0 ||
	    entity->stopped)
		return true;

	return false;
}

/* Return true if entity could provide a job. */
bool drm_sched_entity_is_ready(struct drm_sched_entity *entity)
{
	if (spsc_queue_peek(&entity->job_queue) == NULL)
		return false;

	if (READ_ONCE(entity->dependency))
		return false;

	return true;
}

/**
 * drm_sched_entity_error - return error of last scheduled job
 * @entity: scheduler entity to check
 *
 * Opportunistically return the error of the last scheduled job. Result can
 * change any time when new jobs are pushed to the hw.
 */
int drm_sched_entity_error(struct drm_sched_entity *entity)
{
	struct dma_fence *fence;
	int r;

	rcu_read_lock();
	fence = rcu_dereference(entity->last_scheduled);
	r = fence ? fence->error : 0;
	rcu_read_unlock();

	return r;
}
EXPORT_SYMBOL(drm_sched_entity_error);

static void drm_sched_entity_kill_jobs_work(struct work_struct *wrk)
{
	struct drm_sched_job *job = container_of(wrk, typeof(*job), work);

	drm_sched_fence_finished(job->s_fence, -ESRCH);
	WARN_ON(job->s_fence->parent);
	job->sched->ops->free_job(job);
}

/* Signal the scheduler finished fence when the entity in question is killed. */
static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
					  struct dma_fence_cb *cb)
{
	struct drm_sched_job *job = container_of(cb, struct drm_sched_job,
						 finish_cb);
	unsigned long index;

	dma_fence_put(f);

	/* Wait for all dependencies to avoid data corruptions */
	xa_for_each(&job->dependencies, index, f) {
		struct drm_sched_fence *s_fence = to_drm_sched_fence(f);

		if (s_fence && f == &s_fence->scheduled) {
			/* The dependencies array had a reference on the scheduled
			 * fence, and the finished fence refcount might have
			 * dropped to zero. Use dma_fence_get_rcu() so we get
			 * a NULL fence in that case.
			 */
			f = dma_fence_get_rcu(&s_fence->finished);

			/* Now that we have a reference on the finished fence,
			 * we can release the reference the dependencies array
			 * had on the scheduled fence.
			 */
			dma_fence_put(&s_fence->scheduled);
		}

		xa_erase(&job->dependencies, index);
		if (f && !dma_fence_add_callback(f, &job->finish_cb,
						 drm_sched_entity_kill_jobs_cb))
			return;

		dma_fence_put(f);
	}

	INIT_WORK(&job->work, drm_sched_entity_kill_jobs_work);
	schedule_work(&job->work);
}

/* Remove the entity from the scheduler and kill all pending jobs */
static void drm_sched_entity_kill(struct drm_sched_entity *entity)
{
	struct drm_sched_job *job;
	struct dma_fence *prev;

	if (!entity->rq)
		return;

	spin_lock(&entity->rq_lock);
	entity->stopped = true;
	drm_sched_rq_remove_entity(entity->rq, entity);
	spin_unlock(&entity->rq_lock);

	/* Make sure this entity is not used by the scheduler at the moment */
	wait_for_completion(&entity->entity_idle);

	/* The entity is guaranteed to not be used by the scheduler */
	prev = rcu_dereference_check(entity->last_scheduled, true);
	dma_fence_get(prev);
	while ((job = to_drm_sched_job(spsc_queue_pop(&entity->job_queue)))) {
		struct drm_sched_fence *s_fence = job->s_fence;

		dma_fence_get(&s_fence->finished);
		if (!prev || dma_fence_add_callback(prev, &job->finish_cb,
					   drm_sched_entity_kill_jobs_cb))
			drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb);

		prev = &s_fence->finished;
	}
	dma_fence_put(prev);
}

/**
 * drm_sched_entity_flush - Flush a context entity
 *
 * @entity: scheduler entity
 * @timeout: time to wait in for Q to become empty in jiffies.
 *
 * Splitting drm_sched_entity_fini() into two functions, The first one does the
 * waiting, removes the entity from the runqueue and returns an error when the
 * process was killed.
 *
 * Returns the remaining time in jiffies left from the input timeout
 */
long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
{
	struct drm_gpu_scheduler *sched;
	struct task_struct *last_user;
	long ret = timeout;

	if (!entity->rq)
		return 0;

	sched = entity->rq->sched;
	/**
	 * The client will not queue more IBs during this fini, consume existing
	 * queued IBs or discard them on SIGKILL
	 */
	if (current->flags & PF_EXITING) {
		if (timeout)
			ret = wait_event_timeout(
					sched->job_scheduled,
					drm_sched_entity_is_idle(entity),
					timeout);
	} else {
		wait_event_killable(sched->job_scheduled,
				    drm_sched_entity_is_idle(entity));
	}

	/* For killed process disable any more IBs enqueue right now */
	last_user = cmpxchg(&entity->last_user, current->group_leader, NULL);
	if ((!last_user || last_user == current->group_leader) &&
	    (current->flags & PF_EXITING) && (current->exit_code == SIGKILL))
		drm_sched_entity_kill(entity);

	return ret;
}
EXPORT_SYMBOL(drm_sched_entity_flush);

/**
 * drm_sched_entity_fini - Destroy a context entity
 *
 * @entity: scheduler entity
 *
 * Cleanups up @entity which has been initialized by drm_sched_entity_init().
 *
 * If there are potentially job still in flight or getting newly queued
 * drm_sched_entity_flush() must be called first. This function then goes over
 * the entity and signals all jobs with an error code if the process was killed.
 */
void drm_sched_entity_fini(struct drm_sched_entity *entity)
{
	/*
	 * If consumption of existing IBs wasn't completed. Forcefully remove
	 * them here. Also makes sure that the scheduler won't touch this entity
	 * any more.
	 */
	drm_sched_entity_kill(entity);

	if (entity->dependency) {
		dma_fence_remove_callback(entity->dependency, &entity->cb);
		dma_fence_put(entity->dependency);
		entity->dependency = NULL;
	}

	dma_fence_put(rcu_dereference_check(entity->last_scheduled, true));
	RCU_INIT_POINTER(entity->last_scheduled, NULL);
}
EXPORT_SYMBOL(drm_sched_entity_fini);

/**
 * drm_sched_entity_destroy - Destroy a context entity
 * @entity: scheduler entity
 *
 * Calls drm_sched_entity_flush() and drm_sched_entity_fini() as a
 * convenience wrapper.
 */
void drm_sched_entity_destroy(struct drm_sched_entity *entity)
{
	drm_sched_entity_flush(entity, MAX_WAIT_SCHED_ENTITY_Q_EMPTY);
	drm_sched_entity_fini(entity);
}
EXPORT_SYMBOL(drm_sched_entity_destroy);

/* drm_sched_entity_clear_dep - callback to clear the entities dependency */
static void drm_sched_entity_clear_dep(struct dma_fence *f,
				       struct dma_fence_cb *cb)
{
	struct drm_sched_entity *entity =
		container_of(cb, struct drm_sched_entity, cb);

	entity->dependency = NULL;
	dma_fence_put(f);
}

/*
 * drm_sched_entity_clear_dep - callback to clear the entities dependency and
 * wake up scheduler
 */
static void drm_sched_entity_wakeup(struct dma_fence *f,
				    struct dma_fence_cb *cb)
{
	struct drm_sched_entity *entity =
		container_of(cb, struct drm_sched_entity, cb);

	drm_sched_entity_clear_dep(f, cb);
	drm_sched_wakeup(entity->rq->sched);
}

/**
 * drm_sched_entity_set_priority - Sets priority of the entity
 *
 * @entity: scheduler entity
 * @priority: scheduler priority
 *
 * Update the priority of runqueus used for the entity.
 */
void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
				   enum drm_sched_priority priority)
{
	spin_lock(&entity->rq_lock);
	entity->priority = priority;
	spin_unlock(&entity->rq_lock);
}
EXPORT_SYMBOL(drm_sched_entity_set_priority);

/*
 * Add a callback to the current dependency of the entity to wake up the
 * scheduler when the entity becomes available.
 */
static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
{
	struct drm_gpu_scheduler *sched = entity->rq->sched;
	struct dma_fence *fence = entity->dependency;
	struct drm_sched_fence *s_fence;

	if (fence->context == entity->fence_context ||
	    fence->context == entity->fence_context + 1) {
		/*
		 * Fence is a scheduled/finished fence from a job
		 * which belongs to the same entity, we can ignore
		 * fences from ourself
		 */
		dma_fence_put(entity->dependency);
		return false;
	}

	s_fence = to_drm_sched_fence(fence);
	if (!fence->error && s_fence && s_fence->sched == sched &&
	    !test_bit(DRM_SCHED_FENCE_DONT_PIPELINE, &fence->flags)) {

		/*
		 * Fence is from the same scheduler, only need to wait for
		 * it to be scheduled
		 */
		fence = dma_fence_get(&s_fence->scheduled);
		dma_fence_put(entity->dependency);
		entity->dependency = fence;
		if (!dma_fence_add_callback(fence, &entity->cb,
					    drm_sched_entity_clear_dep))
			return true;

		/* Ignore it when it is already scheduled */
		dma_fence_put(fence);
		return false;
	}

	if (!dma_fence_add_callback(entity->dependency, &entity->cb,
				    drm_sched_entity_wakeup))
		return true;

	dma_fence_put(entity->dependency);
	return false;
}

static struct dma_fence *
drm_sched_job_dependency(struct drm_sched_job *job,
			 struct drm_sched_entity *entity)
{
	struct dma_fence *f;

	/* We keep the fence around, so we can iterate over all dependencies
	 * in drm_sched_entity_kill_jobs_cb() to ensure all deps are signaled
	 * before killing the job.
	 */
	f = xa_load(&job->dependencies, job->last_dependency);
	if (f) {
		job->last_dependency++;
		return dma_fence_get(f);
	}

	if (job->sched->ops->prepare_job)
		return job->sched->ops->prepare_job(job, entity);

	return NULL;
}

struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
{
	struct drm_sched_job *sched_job;

	sched_job = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
	if (!sched_job)
		return NULL;

	while ((entity->dependency =
			drm_sched_job_dependency(sched_job, entity))) {
		trace_drm_sched_job_wait_dep(sched_job, entity->dependency);

		if (drm_sched_entity_add_dependency_cb(entity))
			return NULL;
	}

	/* skip jobs from entity that marked guilty */
	if (entity->guilty && atomic_read(entity->guilty))
		dma_fence_set_error(&sched_job->s_fence->finished, -ECANCELED);

	dma_fence_put(rcu_dereference_check(entity->last_scheduled, true));
	rcu_assign_pointer(entity->last_scheduled,
			   dma_fence_get(&sched_job->s_fence->finished));

	/*
	 * If the queue is empty we allow drm_sched_entity_select_rq() to
	 * locklessly access ->last_scheduled. This only works if we set the
	 * pointer before we dequeue and if we a write barrier here.
	 */
	smp_wmb();

	spsc_queue_pop(&entity->job_queue);

	/*
	 * Update the entity's location in the min heap according to
	 * the timestamp of the next job, if any.
	 */
	if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) {
		struct drm_sched_job *next;

		next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
		if (next)
			drm_sched_rq_update_fifo(entity, next->submit_ts);
	}

	/* Jobs and entities might have different lifecycles. Since we're
	 * removing the job from the entities queue, set the jobs entity pointer
	 * to NULL to prevent any future access of the entity through this job.
	 */
	sched_job->entity = NULL;

	return sched_job;
}

void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
{
	struct dma_fence *fence;
	struct drm_gpu_scheduler *sched;
	struct drm_sched_rq *rq;

	/* single possible engine and already selected */
	if (!entity->sched_list)
		return;

	/* queue non-empty, stay on the same engine */
	if (spsc_queue_count(&entity->job_queue))
		return;

	/*
	 * Only when the queue is empty are we guaranteed that the scheduler
	 * thread cannot change ->last_scheduled. To enforce ordering we need
	 * a read barrier here. See drm_sched_entity_pop_job() for the other
	 * side.
	 */
	smp_rmb();

	fence = rcu_dereference_check(entity->last_scheduled, true);

	/* stay on the same engine if the previous job hasn't finished */
	if (fence && !dma_fence_is_signaled(fence))
		return;

	spin_lock(&entity->rq_lock);
	sched = drm_sched_pick_best(entity->sched_list, entity->num_sched_list);
	rq = sched ? sched->sched_rq[entity->priority] : NULL;
	if (rq != entity->rq) {
		drm_sched_rq_remove_entity(entity->rq, entity);
		entity->rq = rq;
	}
	spin_unlock(&entity->rq_lock);

	if (entity->num_sched_list == 1)
		entity->sched_list = NULL;
}

/**
 * drm_sched_entity_push_job - Submit a job to the entity's job queue
 * @sched_job: job to submit
 *
 * Note: To guarantee that the order of insertion to queue matches the job's
 * fence sequence number this function should be called with drm_sched_job_arm()
 * under common lock for the struct drm_sched_entity that was set up for
 * @sched_job in drm_sched_job_init().
 *
 * Returns 0 for success, negative error code otherwise.
 */
void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
{
	struct drm_sched_entity *entity = sched_job->entity;
	bool first;
	ktime_t submit_ts;

	trace_drm_sched_job(sched_job, entity);
	atomic_inc(entity->rq->sched->score);
	WRITE_ONCE(entity->last_user, current->group_leader);

	/*
	 * After the sched_job is pushed into the entity queue, it may be
	 * completed and freed up at any time. We can no longer access it.
	 * Make sure to set the submit_ts first, to avoid a race.
	 */
	sched_job->submit_ts = submit_ts = ktime_get();
	first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);

	/* first job wakes up scheduler */
	if (first) {
		struct drm_gpu_scheduler *sched;
		struct drm_sched_rq *rq;

		/* Add the entity to the run queue */
		spin_lock(&entity->rq_lock);
		if (entity->stopped) {
			spin_unlock(&entity->rq_lock);

			DRM_ERROR("Trying to push to a killed entity\n");
			return;
		}

		rq = entity->rq;
		sched = rq->sched;

		drm_sched_rq_add_entity(rq, entity);
		spin_unlock(&entity->rq_lock);

		if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
			drm_sched_rq_update_fifo(entity, submit_ts);

		drm_sched_wakeup(sched);
	}
}
EXPORT_SYMBOL(drm_sched_entity_push_job);