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 	entity->last_scheduled = NULL;
76 
77 	if(num_sched_list)
78 		entity->rq = &sched_list[0]->sched_rq[entity->priority];
79 
80 	init_completion(&entity->entity_idle);
81 
82 	/* We start in an idle state. */
83 	complete(&entity->entity_idle);
84 
85 	spin_lock_init(&entity->rq_lock);
86 	spsc_queue_init(&entity->job_queue);
87 
88 	atomic_set(&entity->fence_seq, 0);
89 	entity->fence_context = dma_fence_context_alloc(2);
90 
91 	return 0;
92 }
93 EXPORT_SYMBOL(drm_sched_entity_init);
94 
95 /**
96  * drm_sched_entity_modify_sched - Modify sched of an entity
97  * @entity: scheduler entity to init
98  * @sched_list: the list of new drm scheds which will replace
99  *		 existing entity->sched_list
100  * @num_sched_list: number of drm sched in sched_list
101  *
102  * Note that this must be called under the same common lock for @entity as
103  * drm_sched_job_arm() and drm_sched_entity_push_job(), or the driver needs to
104  * guarantee through some other means that this is never called while new jobs
105  * can be pushed to @entity.
106  */
107 void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
108 				    struct drm_gpu_scheduler **sched_list,
109 				    unsigned int num_sched_list)
110 {
111 	WARN_ON(!num_sched_list || !sched_list);
112 
113 	entity->sched_list = sched_list;
114 	entity->num_sched_list = num_sched_list;
115 }
116 EXPORT_SYMBOL(drm_sched_entity_modify_sched);
117 
118 static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity)
119 {
120 	rmb(); /* for list_empty to work without lock */
121 
122 	if (list_empty(&entity->list) ||
123 	    spsc_queue_count(&entity->job_queue) == 0 ||
124 	    entity->stopped)
125 		return true;
126 
127 	return false;
128 }
129 
130 /* Return true if entity could provide a job. */
131 bool drm_sched_entity_is_ready(struct drm_sched_entity *entity)
132 {
133 	if (spsc_queue_peek(&entity->job_queue) == NULL)
134 		return false;
135 
136 	if (READ_ONCE(entity->dependency))
137 		return false;
138 
139 	return true;
140 }
141 
142 /**
143  * drm_sched_entity_flush - Flush a context entity
144  *
145  * @entity: scheduler entity
146  * @timeout: time to wait in for Q to become empty in jiffies.
147  *
148  * Splitting drm_sched_entity_fini() into two functions, The first one does the
149  * waiting, removes the entity from the runqueue and returns an error when the
150  * process was killed.
151  *
152  * Returns the remaining time in jiffies left from the input timeout
153  */
154 long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
155 {
156 	struct drm_gpu_scheduler *sched;
157 	struct task_struct *last_user;
158 	long ret = timeout;
159 
160 	if (!entity->rq)
161 		return 0;
162 
163 	sched = entity->rq->sched;
164 	/**
165 	 * The client will not queue more IBs during this fini, consume existing
166 	 * queued IBs or discard them on SIGKILL
167 	 */
168 	if (current->flags & PF_EXITING) {
169 		if (timeout)
170 			ret = wait_event_timeout(
171 					sched->job_scheduled,
172 					drm_sched_entity_is_idle(entity),
173 					timeout);
174 	} else {
175 		wait_event_killable(sched->job_scheduled,
176 				    drm_sched_entity_is_idle(entity));
177 	}
178 
179 	/* For killed process disable any more IBs enqueue right now */
180 	last_user = cmpxchg(&entity->last_user, current->group_leader, NULL);
181 	if ((!last_user || last_user == current->group_leader) &&
182 	    (current->flags & PF_EXITING) && (current->exit_code == SIGKILL)) {
183 		spin_lock(&entity->rq_lock);
184 		entity->stopped = true;
185 		drm_sched_rq_remove_entity(entity->rq, entity);
186 		spin_unlock(&entity->rq_lock);
187 	}
188 
189 	return ret;
190 }
191 EXPORT_SYMBOL(drm_sched_entity_flush);
192 
193 static void drm_sched_entity_kill_jobs_work(struct work_struct *wrk)
194 {
195 	struct drm_sched_job *job = container_of(wrk, typeof(*job), work);
196 
197 	drm_sched_fence_finished(job->s_fence);
198 	WARN_ON(job->s_fence->parent);
199 	job->sched->ops->free_job(job);
200 }
201 
202 
203 /* Signal the scheduler finished fence when the entity in question is killed. */
204 static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
205 					  struct dma_fence_cb *cb)
206 {
207 	struct drm_sched_job *job = container_of(cb, struct drm_sched_job,
208 						 finish_cb);
209 
210 	INIT_WORK(&job->work, drm_sched_entity_kill_jobs_work);
211 	schedule_work(&job->work);
212 }
213 
214 static struct dma_fence *
215 drm_sched_job_dependency(struct drm_sched_job *job,
216 			 struct drm_sched_entity *entity)
217 {
218 	if (!xa_empty(&job->dependencies))
219 		return xa_erase(&job->dependencies, job->last_dependency++);
220 
221 	if (job->sched->ops->dependency)
222 		return job->sched->ops->dependency(job, entity);
223 
224 	return NULL;
225 }
226 
227 static void drm_sched_entity_kill_jobs(struct drm_sched_entity *entity)
228 {
229 	struct drm_sched_job *job;
230 	struct dma_fence *f;
231 	int r;
232 
233 	while ((job = to_drm_sched_job(spsc_queue_pop(&entity->job_queue)))) {
234 		struct drm_sched_fence *s_fence = job->s_fence;
235 
236 		/* Wait for all dependencies to avoid data corruptions */
237 		while ((f = drm_sched_job_dependency(job, entity)))
238 			dma_fence_wait(f, false);
239 
240 		drm_sched_fence_scheduled(s_fence);
241 		dma_fence_set_error(&s_fence->finished, -ESRCH);
242 
243 		/*
244 		 * When pipe is hanged by older entity, new entity might
245 		 * not even have chance to submit it's first job to HW
246 		 * and so entity->last_scheduled will remain NULL
247 		 */
248 		if (!entity->last_scheduled) {
249 			drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb);
250 			continue;
251 		}
252 
253 		r = dma_fence_add_callback(entity->last_scheduled,
254 					   &job->finish_cb,
255 					   drm_sched_entity_kill_jobs_cb);
256 		if (r == -ENOENT)
257 			drm_sched_entity_kill_jobs_cb(NULL, &job->finish_cb);
258 		else if (r)
259 			DRM_ERROR("fence add callback failed (%d)\n", r);
260 	}
261 }
262 
263 /**
264  * drm_sched_entity_fini - Destroy a context entity
265  *
266  * @entity: scheduler entity
267  *
268  * Cleanups up @entity which has been initialized by drm_sched_entity_init().
269  *
270  * If there are potentially job still in flight or getting newly queued
271  * drm_sched_entity_flush() must be called first. This function then goes over
272  * the entity and signals all jobs with an error code if the process was killed.
273  */
274 void drm_sched_entity_fini(struct drm_sched_entity *entity)
275 {
276 	struct drm_gpu_scheduler *sched = NULL;
277 
278 	if (entity->rq) {
279 		sched = entity->rq->sched;
280 		drm_sched_rq_remove_entity(entity->rq, entity);
281 	}
282 
283 	/* Consumption of existing IBs wasn't completed. Forcefully
284 	 * remove them here.
285 	 */
286 	if (spsc_queue_count(&entity->job_queue)) {
287 		if (sched) {
288 			/*
289 			 * Wait for thread to idle to make sure it isn't processing
290 			 * this entity.
291 			 */
292 			wait_for_completion(&entity->entity_idle);
293 
294 		}
295 		if (entity->dependency) {
296 			dma_fence_remove_callback(entity->dependency,
297 						  &entity->cb);
298 			dma_fence_put(entity->dependency);
299 			entity->dependency = NULL;
300 		}
301 
302 		drm_sched_entity_kill_jobs(entity);
303 	}
304 
305 	dma_fence_put(entity->last_scheduled);
306 	entity->last_scheduled = NULL;
307 }
308 EXPORT_SYMBOL(drm_sched_entity_fini);
309 
310 /**
311  * drm_sched_entity_destroy - Destroy a context entity
312  * @entity: scheduler entity
313  *
314  * Calls drm_sched_entity_flush() and drm_sched_entity_fini() as a
315  * convenience wrapper.
316  */
317 void drm_sched_entity_destroy(struct drm_sched_entity *entity)
318 {
319 	drm_sched_entity_flush(entity, MAX_WAIT_SCHED_ENTITY_Q_EMPTY);
320 	drm_sched_entity_fini(entity);
321 }
322 EXPORT_SYMBOL(drm_sched_entity_destroy);
323 
324 /* drm_sched_entity_clear_dep - callback to clear the entities dependency */
325 static void drm_sched_entity_clear_dep(struct dma_fence *f,
326 				       struct dma_fence_cb *cb)
327 {
328 	struct drm_sched_entity *entity =
329 		container_of(cb, struct drm_sched_entity, cb);
330 
331 	entity->dependency = NULL;
332 	dma_fence_put(f);
333 }
334 
335 /*
336  * drm_sched_entity_clear_dep - callback to clear the entities dependency and
337  * wake up scheduler
338  */
339 static void drm_sched_entity_wakeup(struct dma_fence *f,
340 				    struct dma_fence_cb *cb)
341 {
342 	struct drm_sched_entity *entity =
343 		container_of(cb, struct drm_sched_entity, cb);
344 
345 	drm_sched_entity_clear_dep(f, cb);
346 	drm_sched_wakeup(entity->rq->sched);
347 }
348 
349 /**
350  * drm_sched_entity_set_priority - Sets priority of the entity
351  *
352  * @entity: scheduler entity
353  * @priority: scheduler priority
354  *
355  * Update the priority of runqueus used for the entity.
356  */
357 void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
358 				   enum drm_sched_priority priority)
359 {
360 	spin_lock(&entity->rq_lock);
361 	entity->priority = priority;
362 	spin_unlock(&entity->rq_lock);
363 }
364 EXPORT_SYMBOL(drm_sched_entity_set_priority);
365 
366 /*
367  * Add a callback to the current dependency of the entity to wake up the
368  * scheduler when the entity becomes available.
369  */
370 static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
371 {
372 	struct drm_gpu_scheduler *sched = entity->rq->sched;
373 	struct dma_fence *fence = entity->dependency;
374 	struct drm_sched_fence *s_fence;
375 
376 	if (fence->context == entity->fence_context ||
377 	    fence->context == entity->fence_context + 1) {
378 		/*
379 		 * Fence is a scheduled/finished fence from a job
380 		 * which belongs to the same entity, we can ignore
381 		 * fences from ourself
382 		 */
383 		dma_fence_put(entity->dependency);
384 		return false;
385 	}
386 
387 	s_fence = to_drm_sched_fence(fence);
388 	if (s_fence && s_fence->sched == sched) {
389 
390 		/*
391 		 * Fence is from the same scheduler, only need to wait for
392 		 * it to be scheduled
393 		 */
394 		fence = dma_fence_get(&s_fence->scheduled);
395 		dma_fence_put(entity->dependency);
396 		entity->dependency = fence;
397 		if (!dma_fence_add_callback(fence, &entity->cb,
398 					    drm_sched_entity_clear_dep))
399 			return true;
400 
401 		/* Ignore it when it is already scheduled */
402 		dma_fence_put(fence);
403 		return false;
404 	}
405 
406 	if (!dma_fence_add_callback(entity->dependency, &entity->cb,
407 				    drm_sched_entity_wakeup))
408 		return true;
409 
410 	dma_fence_put(entity->dependency);
411 	return false;
412 }
413 
414 struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
415 {
416 	struct drm_sched_job *sched_job;
417 
418 	sched_job = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
419 	if (!sched_job)
420 		return NULL;
421 
422 	while ((entity->dependency =
423 			drm_sched_job_dependency(sched_job, entity))) {
424 		trace_drm_sched_job_wait_dep(sched_job, entity->dependency);
425 
426 		if (drm_sched_entity_add_dependency_cb(entity))
427 			return NULL;
428 	}
429 
430 	/* skip jobs from entity that marked guilty */
431 	if (entity->guilty && atomic_read(entity->guilty))
432 		dma_fence_set_error(&sched_job->s_fence->finished, -ECANCELED);
433 
434 	dma_fence_put(entity->last_scheduled);
435 
436 	entity->last_scheduled = dma_fence_get(&sched_job->s_fence->finished);
437 
438 	/*
439 	 * If the queue is empty we allow drm_sched_entity_select_rq() to
440 	 * locklessly access ->last_scheduled. This only works if we set the
441 	 * pointer before we dequeue and if we a write barrier here.
442 	 */
443 	smp_wmb();
444 
445 	spsc_queue_pop(&entity->job_queue);
446 	return sched_job;
447 }
448 
449 void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
450 {
451 	struct dma_fence *fence;
452 	struct drm_gpu_scheduler *sched;
453 	struct drm_sched_rq *rq;
454 
455 	/* single possible engine and already selected */
456 	if (!entity->sched_list)
457 		return;
458 
459 	/* queue non-empty, stay on the same engine */
460 	if (spsc_queue_count(&entity->job_queue))
461 		return;
462 
463 	/*
464 	 * Only when the queue is empty are we guaranteed that the scheduler
465 	 * thread cannot change ->last_scheduled. To enforce ordering we need
466 	 * a read barrier here. See drm_sched_entity_pop_job() for the other
467 	 * side.
468 	 */
469 	smp_rmb();
470 
471 	fence = entity->last_scheduled;
472 
473 	/* stay on the same engine if the previous job hasn't finished */
474 	if (fence && !dma_fence_is_signaled(fence))
475 		return;
476 
477 	spin_lock(&entity->rq_lock);
478 	sched = drm_sched_pick_best(entity->sched_list, entity->num_sched_list);
479 	rq = sched ? &sched->sched_rq[entity->priority] : NULL;
480 	if (rq != entity->rq) {
481 		drm_sched_rq_remove_entity(entity->rq, entity);
482 		entity->rq = rq;
483 	}
484 	spin_unlock(&entity->rq_lock);
485 
486 	if (entity->num_sched_list == 1)
487 		entity->sched_list = NULL;
488 }
489 
490 /**
491  * drm_sched_entity_push_job - Submit a job to the entity's job queue
492  * @sched_job: job to submit
493  *
494  * Note: To guarantee that the order of insertion to queue matches the job's
495  * fence sequence number this function should be called with drm_sched_job_arm()
496  * under common lock for the struct drm_sched_entity that was set up for
497  * @sched_job in drm_sched_job_init().
498  *
499  * Returns 0 for success, negative error code otherwise.
500  */
501 void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
502 {
503 	struct drm_sched_entity *entity = sched_job->entity;
504 	bool first;
505 
506 	trace_drm_sched_job(sched_job, entity);
507 	atomic_inc(entity->rq->sched->score);
508 	WRITE_ONCE(entity->last_user, current->group_leader);
509 	first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
510 
511 	/* first job wakes up scheduler */
512 	if (first) {
513 		/* Add the entity to the run queue */
514 		spin_lock(&entity->rq_lock);
515 		if (entity->stopped) {
516 			spin_unlock(&entity->rq_lock);
517 
518 			DRM_ERROR("Trying to push to a killed entity\n");
519 			return;
520 		}
521 		drm_sched_rq_add_entity(entity->rq, entity);
522 		spin_unlock(&entity->rq_lock);
523 		drm_sched_wakeup(entity->rq->sched);
524 	}
525 }
526 EXPORT_SYMBOL(drm_sched_entity_push_job);
527