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