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 */
 59int 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	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}
 94EXPORT_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 */
108void 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}
117EXPORT_SYMBOL(drm_sched_entity_modify_sched);
118
119static 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. */
132bool 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
143static void drm_sched_entity_kill_jobs_work(struct work_struct *wrk)
144{
145	struct drm_sched_job *job = container_of(wrk, typeof(*job), work);
146
147	drm_sched_fence_finished(job->s_fence);
148	WARN_ON(job->s_fence->parent);
149	job->sched->ops->free_job(job);
150}
151
152/* Signal the scheduler finished fence when the entity in question is killed. */
153static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
154					  struct dma_fence_cb *cb)
155{
156	struct drm_sched_job *job = container_of(cb, struct drm_sched_job,
157						 finish_cb);
158	int r;
159
160	dma_fence_put(f);
161
162	/* Wait for all dependencies to avoid data corruptions */
163	while (!xa_empty(&job->dependencies)) {
164		f = xa_erase(&job->dependencies, job->last_dependency++);
165		r = dma_fence_add_callback(f, &job->finish_cb,
166					   drm_sched_entity_kill_jobs_cb);
167		if (!r)
168			return;
169
170		dma_fence_put(f);
171	}
172
173	INIT_WORK(&job->work, drm_sched_entity_kill_jobs_work);
174	schedule_work(&job->work);
175}
176
177/* Remove the entity from the scheduler and kill all pending jobs */
178static void drm_sched_entity_kill(struct drm_sched_entity *entity)
179{
180	struct drm_sched_job *job;
181	struct dma_fence *prev;
182
183	if (!entity->rq)
184		return;
185
186	spin_lock(&entity->rq_lock);
187	entity->stopped = true;
188	drm_sched_rq_remove_entity(entity->rq, entity);
189	spin_unlock(&entity->rq_lock);
190
191	/* Make sure this entity is not used by the scheduler at the moment */
192	wait_for_completion(&entity->entity_idle);
193
194	prev = dma_fence_get(entity->last_scheduled);
195	while ((job = to_drm_sched_job(spsc_queue_pop(&entity->job_queue)))) {
196		struct drm_sched_fence *s_fence = job->s_fence;
197
198		dma_fence_set_error(&s_fence->finished, -ESRCH);
199
200		dma_fence_get(&s_fence->finished);
201		if (!prev || dma_fence_add_callback(prev, &job->finish_cb,
202					   drm_sched_entity_kill_jobs_cb))
203			drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb);
204
205		prev = &s_fence->finished;
206	}
207	dma_fence_put(prev);
208}
209
210/**
211 * drm_sched_entity_flush - Flush a context entity
212 *
213 * @entity: scheduler entity
214 * @timeout: time to wait in for Q to become empty in jiffies.
215 *
216 * Splitting drm_sched_entity_fini() into two functions, The first one does the
217 * waiting, removes the entity from the runqueue and returns an error when the
218 * process was killed.
219 *
220 * Returns the remaining time in jiffies left from the input timeout
221 */
222long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
223{
224	struct drm_gpu_scheduler *sched;
225	struct task_struct *last_user;
226	long ret = timeout;
227
228	if (!entity->rq)
229		return 0;
230
231	sched = entity->rq->sched;
232	/**
233	 * The client will not queue more IBs during this fini, consume existing
234	 * queued IBs or discard them on SIGKILL
235	 */
236	if (current->flags & PF_EXITING) {
237		if (timeout)
238			ret = wait_event_timeout(
239					sched->job_scheduled,
240					drm_sched_entity_is_idle(entity),
241					timeout);
242	} else {
243		wait_event_killable(sched->job_scheduled,
244				    drm_sched_entity_is_idle(entity));
245	}
246
247	/* For killed process disable any more IBs enqueue right now */
248	last_user = cmpxchg(&entity->last_user, current->group_leader, NULL);
249	if ((!last_user || last_user == current->group_leader) &&
250	    (current->flags & PF_EXITING) && (current->exit_code == SIGKILL))
251		drm_sched_entity_kill(entity);
252
253	return ret;
254}
255EXPORT_SYMBOL(drm_sched_entity_flush);
256
257/**
258 * drm_sched_entity_fini - Destroy a context entity
259 *
260 * @entity: scheduler entity
261 *
262 * Cleanups up @entity which has been initialized by drm_sched_entity_init().
263 *
264 * If there are potentially job still in flight or getting newly queued
265 * drm_sched_entity_flush() must be called first. This function then goes over
266 * the entity and signals all jobs with an error code if the process was killed.
267 */
268void drm_sched_entity_fini(struct drm_sched_entity *entity)
269{
270	/*
271	 * If consumption of existing IBs wasn't completed. Forcefully remove
272	 * them here. Also makes sure that the scheduler won't touch this entity
273	 * any more.
274	 */
275	drm_sched_entity_kill(entity);
276
277	if (entity->dependency) {
278		dma_fence_remove_callback(entity->dependency, &entity->cb);
279		dma_fence_put(entity->dependency);
280		entity->dependency = NULL;
281	}
282
283	dma_fence_put(entity->last_scheduled);
284	entity->last_scheduled = NULL;
285}
286EXPORT_SYMBOL(drm_sched_entity_fini);
287
288/**
289 * drm_sched_entity_destroy - Destroy a context entity
290 * @entity: scheduler entity
291 *
292 * Calls drm_sched_entity_flush() and drm_sched_entity_fini() as a
293 * convenience wrapper.
294 */
295void drm_sched_entity_destroy(struct drm_sched_entity *entity)
296{
297	drm_sched_entity_flush(entity, MAX_WAIT_SCHED_ENTITY_Q_EMPTY);
298	drm_sched_entity_fini(entity);
299}
300EXPORT_SYMBOL(drm_sched_entity_destroy);
301
302/* drm_sched_entity_clear_dep - callback to clear the entities dependency */
303static void drm_sched_entity_clear_dep(struct dma_fence *f,
304				       struct dma_fence_cb *cb)
305{
306	struct drm_sched_entity *entity =
307		container_of(cb, struct drm_sched_entity, cb);
308
309	entity->dependency = NULL;
310	dma_fence_put(f);
311}
312
313/*
314 * drm_sched_entity_clear_dep - callback to clear the entities dependency and
315 * wake up scheduler
316 */
317static void drm_sched_entity_wakeup(struct dma_fence *f,
318				    struct dma_fence_cb *cb)
319{
320	struct drm_sched_entity *entity =
321		container_of(cb, struct drm_sched_entity, cb);
322
323	drm_sched_entity_clear_dep(f, cb);
324	drm_sched_wakeup(entity->rq->sched);
325}
326
327/**
328 * drm_sched_entity_set_priority - Sets priority of the entity
329 *
330 * @entity: scheduler entity
331 * @priority: scheduler priority
332 *
333 * Update the priority of runqueus used for the entity.
334 */
335void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
336				   enum drm_sched_priority priority)
337{
338	spin_lock(&entity->rq_lock);
339	entity->priority = priority;
340	spin_unlock(&entity->rq_lock);
341}
342EXPORT_SYMBOL(drm_sched_entity_set_priority);
343
344/*
345 * Add a callback to the current dependency of the entity to wake up the
346 * scheduler when the entity becomes available.
347 */
348static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
349{
350	struct drm_gpu_scheduler *sched = entity->rq->sched;
351	struct dma_fence *fence = entity->dependency;
352	struct drm_sched_fence *s_fence;
353
354	if (fence->context == entity->fence_context ||
355	    fence->context == entity->fence_context + 1) {
356		/*
357		 * Fence is a scheduled/finished fence from a job
358		 * which belongs to the same entity, we can ignore
359		 * fences from ourself
360		 */
361		dma_fence_put(entity->dependency);
362		return false;
363	}
364
365	s_fence = to_drm_sched_fence(fence);
366	if (s_fence && s_fence->sched == sched &&
367	    !test_bit(DRM_SCHED_FENCE_DONT_PIPELINE, &fence->flags)) {
368
369		/*
370		 * Fence is from the same scheduler, only need to wait for
371		 * it to be scheduled
372		 */
373		fence = dma_fence_get(&s_fence->scheduled);
374		dma_fence_put(entity->dependency);
375		entity->dependency = fence;
376		if (!dma_fence_add_callback(fence, &entity->cb,
377					    drm_sched_entity_clear_dep))
378			return true;
379
380		/* Ignore it when it is already scheduled */
381		dma_fence_put(fence);
382		return false;
383	}
384
385	if (!dma_fence_add_callback(entity->dependency, &entity->cb,
386				    drm_sched_entity_wakeup))
387		return true;
388
389	dma_fence_put(entity->dependency);
390	return false;
391}
392
393static struct dma_fence *
394drm_sched_job_dependency(struct drm_sched_job *job,
395			 struct drm_sched_entity *entity)
396{
397	if (!xa_empty(&job->dependencies))
398		return xa_erase(&job->dependencies, job->last_dependency++);
399
400	if (job->sched->ops->prepare_job)
401		return job->sched->ops->prepare_job(job, entity);
402
403	return NULL;
404}
405
406struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
407{
408	struct drm_sched_job *sched_job;
409
410	sched_job = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
411	if (!sched_job)
412		return NULL;
413
414	while ((entity->dependency =
415			drm_sched_job_dependency(sched_job, entity))) {
416		trace_drm_sched_job_wait_dep(sched_job, entity->dependency);
417
418		if (drm_sched_entity_add_dependency_cb(entity))
419			return NULL;
420	}
421
422	/* skip jobs from entity that marked guilty */
423	if (entity->guilty && atomic_read(entity->guilty))
424		dma_fence_set_error(&sched_job->s_fence->finished, -ECANCELED);
425
426	dma_fence_put(entity->last_scheduled);
427
428	entity->last_scheduled = dma_fence_get(&sched_job->s_fence->finished);
429
430	/*
431	 * If the queue is empty we allow drm_sched_entity_select_rq() to
432	 * locklessly access ->last_scheduled. This only works if we set the
433	 * pointer before we dequeue and if we a write barrier here.
434	 */
435	smp_wmb();
436
437	spsc_queue_pop(&entity->job_queue);
438
439	/*
440	 * Update the entity's location in the min heap according to
441	 * the timestamp of the next job, if any.
442	 */
443	if (drm_sched_policy == DRM_SCHED_POLICY_FIFO) {
444		struct drm_sched_job *next;
445
446		next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
447		if (next)
448			drm_sched_rq_update_fifo(entity, next->submit_ts);
449	}
450
451	return sched_job;
452}
453
454void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
455{
456	struct dma_fence *fence;
457	struct drm_gpu_scheduler *sched;
458	struct drm_sched_rq *rq;
459
460	/* single possible engine and already selected */
461	if (!entity->sched_list)
462		return;
463
464	/* queue non-empty, stay on the same engine */
465	if (spsc_queue_count(&entity->job_queue))
466		return;
467
468	/*
469	 * Only when the queue is empty are we guaranteed that the scheduler
470	 * thread cannot change ->last_scheduled. To enforce ordering we need
471	 * a read barrier here. See drm_sched_entity_pop_job() for the other
472	 * side.
473	 */
474	smp_rmb();
475
476	fence = entity->last_scheduled;
477
478	/* stay on the same engine if the previous job hasn't finished */
479	if (fence && !dma_fence_is_signaled(fence))
480		return;
481
482	spin_lock(&entity->rq_lock);
483	sched = drm_sched_pick_best(entity->sched_list, entity->num_sched_list);
484	rq = sched ? &sched->sched_rq[entity->priority] : NULL;
485	if (rq != entity->rq) {
486		drm_sched_rq_remove_entity(entity->rq, entity);
487		entity->rq = rq;
488	}
489	spin_unlock(&entity->rq_lock);
490
491	if (entity->num_sched_list == 1)
492		entity->sched_list = NULL;
493}
494
495/**
496 * drm_sched_entity_push_job - Submit a job to the entity's job queue
497 * @sched_job: job to submit
498 *
499 * Note: To guarantee that the order of insertion to queue matches the job's
500 * fence sequence number this function should be called with drm_sched_job_arm()
501 * under common lock for the struct drm_sched_entity that was set up for
502 * @sched_job in drm_sched_job_init().
503 *
504 * Returns 0 for success, negative error code otherwise.
505 */
506void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
507{
508	struct drm_sched_entity *entity = sched_job->entity;
509	bool first;
510
511	trace_drm_sched_job(sched_job, entity);
512	atomic_inc(entity->rq->sched->score);
513	WRITE_ONCE(entity->last_user, current->group_leader);
514	first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
515	sched_job->submit_ts = ktime_get();
516
517	/* first job wakes up scheduler */
518	if (first) {
519		/* Add the entity to the run queue */
520		spin_lock(&entity->rq_lock);
521		if (entity->stopped) {
522			spin_unlock(&entity->rq_lock);
523
524			DRM_ERROR("Trying to push to a killed entity\n");
525			return;
526		}
527
528		drm_sched_rq_add_entity(entity->rq, entity);
529		spin_unlock(&entity->rq_lock);
530
531		if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
532			drm_sched_rq_update_fifo(entity, sched_job->submit_ts);
533
534		drm_sched_wakeup(entity->rq->sched);
535	}
536}
537EXPORT_SYMBOL(drm_sched_entity_push_job);