summaryrefslogtreecommitdiffstats
path: root/drivers/gpu/drm/i915/i915_active.c
blob: 48e16ad93bbdd83c8a8df15dd49aa540655ad124 (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
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright © 2019 Intel Corporation
 */

#include <linux/debugobjects.h>

#include "gt/intel_engine_pm.h"

#include "i915_drv.h"
#include "i915_active.h"
#include "i915_globals.h"

#define BKL(ref) (&(ref)->i915->drm.struct_mutex)

/*
 * Active refs memory management
 *
 * To be more economical with memory, we reap all the i915_active trees as
 * they idle (when we know the active requests are inactive) and allocate the
 * nodes from a local slab cache to hopefully reduce the fragmentation.
 */
static struct i915_global_active {
	struct i915_global base;
	struct kmem_cache *slab_cache;
} global;

struct active_node {
	struct i915_active_request base;
	struct i915_active *ref;
	struct rb_node node;
	u64 timeline;
};

static inline struct active_node *
node_from_active(struct i915_active_request *active)
{
	return container_of(active, struct active_node, base);
}

#define take_preallocated_barriers(x) llist_del_all(&(x)->preallocated_barriers)

static inline bool is_barrier(const struct i915_active_request *active)
{
	return IS_ERR(rcu_access_pointer(active->request));
}

static inline struct llist_node *barrier_to_ll(struct active_node *node)
{
	GEM_BUG_ON(!is_barrier(&node->base));
	return (struct llist_node *)&node->base.link;
}

static inline struct intel_engine_cs *
__barrier_to_engine(struct active_node *node)
{
	return (struct intel_engine_cs *)READ_ONCE(node->base.link.prev);
}

static inline struct intel_engine_cs *
barrier_to_engine(struct active_node *node)
{
	GEM_BUG_ON(!is_barrier(&node->base));
	return __barrier_to_engine(node);
}

static inline struct active_node *barrier_from_ll(struct llist_node *x)
{
	return container_of((struct list_head *)x,
			    struct active_node, base.link);
}

#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM) && IS_ENABLED(CONFIG_DEBUG_OBJECTS)

static void *active_debug_hint(void *addr)
{
	struct i915_active *ref = addr;

	return (void *)ref->active ?: (void *)ref->retire ?: (void *)ref;
}

static struct debug_obj_descr active_debug_desc = {
	.name = "i915_active",
	.debug_hint = active_debug_hint,
};

static void debug_active_init(struct i915_active *ref)
{
	debug_object_init(ref, &active_debug_desc);
}

static void debug_active_activate(struct i915_active *ref)
{
	debug_object_activate(ref, &active_debug_desc);
}

static void debug_active_deactivate(struct i915_active *ref)
{
	debug_object_deactivate(ref, &active_debug_desc);
}

static void debug_active_fini(struct i915_active *ref)
{
	debug_object_free(ref, &active_debug_desc);
}

static void debug_active_assert(struct i915_active *ref)
{
	debug_object_assert_init(ref, &active_debug_desc);
}

#else

static inline void debug_active_init(struct i915_active *ref) { }
static inline void debug_active_activate(struct i915_active *ref) { }
static inline void debug_active_deactivate(struct i915_active *ref) { }
static inline void debug_active_fini(struct i915_active *ref) { }
static inline void debug_active_assert(struct i915_active *ref) { }

#endif

static void
__active_retire(struct i915_active *ref)
{
	struct active_node *it, *n;
	struct rb_root root;
	bool retire = false;

	lockdep_assert_held(&ref->mutex);

	/* return the unused nodes to our slabcache -- flushing the allocator */
	if (atomic_dec_and_test(&ref->count)) {
		debug_active_deactivate(ref);
		root = ref->tree;
		ref->tree = RB_ROOT;
		ref->cache = NULL;
		retire = true;
	}

	mutex_unlock(&ref->mutex);
	if (!retire)
		return;

	rbtree_postorder_for_each_entry_safe(it, n, &root, node) {
		GEM_BUG_ON(i915_active_request_isset(&it->base));
		kmem_cache_free(global.slab_cache, it);
	}

	/* After the final retire, the entire struct may be freed */
	if (ref->retire)
		ref->retire(ref);
}

static void
active_retire(struct i915_active *ref)
{
	GEM_BUG_ON(!atomic_read(&ref->count));
	if (atomic_add_unless(&ref->count, -1, 1))
		return;

	/* One active may be flushed from inside the acquire of another */
	mutex_lock_nested(&ref->mutex, SINGLE_DEPTH_NESTING);
	__active_retire(ref);
}

static void
node_retire(struct i915_active_request *base, struct i915_request *rq)
{
	active_retire(node_from_active(base)->ref);
}

static struct i915_active_request *
active_instance(struct i915_active *ref, struct intel_timeline *tl)
{
	struct active_node *node, *prealloc;
	struct rb_node **p, *parent;
	u64 idx = tl->fence_context;

	/*
	 * We track the most recently used timeline to skip a rbtree search
	 * for the common case, under typical loads we never need the rbtree
	 * at all. We can reuse the last slot if it is empty, that is
	 * after the previous activity has been retired, or if it matches the
	 * current timeline.
	 */
	node = READ_ONCE(ref->cache);
	if (node && node->timeline == idx)
		return &node->base;

	/* Preallocate a replacement, just in case */
	prealloc = kmem_cache_alloc(global.slab_cache, GFP_KERNEL);
	if (!prealloc)
		return NULL;

	mutex_lock(&ref->mutex);
	GEM_BUG_ON(i915_active_is_idle(ref));

	parent = NULL;
	p = &ref->tree.rb_node;
	while (*p) {
		parent = *p;

		node = rb_entry(parent, struct active_node, node);
		if (node->timeline == idx) {
			kmem_cache_free(global.slab_cache, prealloc);
			goto out;
		}

		if (node->timeline < idx)
			p = &parent->rb_right;
		else
			p = &parent->rb_left;
	}

	node = prealloc;
	i915_active_request_init(&node->base, &tl->mutex, NULL, node_retire);
	node->ref = ref;
	node->timeline = idx;

	rb_link_node(&node->node, parent, p);
	rb_insert_color(&node->node, &ref->tree);

out:
	ref->cache = node;
	mutex_unlock(&ref->mutex);

	BUILD_BUG_ON(offsetof(typeof(*node), base));
	return &node->base;
}

void __i915_active_init(struct drm_i915_private *i915,
			struct i915_active *ref,
			int (*active)(struct i915_active *ref),
			void (*retire)(struct i915_active *ref),
			struct lock_class_key *key)
{
	debug_active_init(ref);

	ref->i915 = i915;
	ref->flags = 0;
	ref->active = active;
	ref->retire = retire;
	ref->tree = RB_ROOT;
	ref->cache = NULL;
	init_llist_head(&ref->preallocated_barriers);
	atomic_set(&ref->count, 0);
	__mutex_init(&ref->mutex, "i915_active", key);
}

static bool ____active_del_barrier(struct i915_active *ref,
				   struct active_node *node,
				   struct intel_engine_cs *engine)

{
	struct llist_node *head = NULL, *tail = NULL;
	struct llist_node *pos, *next;

	GEM_BUG_ON(node->timeline != engine->kernel_context->timeline->fence_context);

	/*
	 * Rebuild the llist excluding our node. We may perform this
	 * outside of the kernel_context timeline mutex and so someone
	 * else may be manipulating the engine->barrier_tasks, in
	 * which case either we or they will be upset :)
	 *
	 * A second __active_del_barrier() will report failure to claim
	 * the active_node and the caller will just shrug and know not to
	 * claim ownership of its node.
	 *
	 * A concurrent i915_request_add_active_barriers() will miss adding
	 * any of the tasks, but we will try again on the next -- and since
	 * we are actively using the barrier, we know that there will be
	 * at least another opportunity when we idle.
	 */
	llist_for_each_safe(pos, next, llist_del_all(&engine->barrier_tasks)) {
		if (node == barrier_from_ll(pos)) {
			node = NULL;
			continue;
		}

		pos->next = head;
		head = pos;
		if (!tail)
			tail = pos;
	}
	if (head)
		llist_add_batch(head, tail, &engine->barrier_tasks);

	return !node;
}

static bool
__active_del_barrier(struct i915_active *ref, struct active_node *node)
{
	return ____active_del_barrier(ref, node, barrier_to_engine(node));
}

int i915_active_ref(struct i915_active *ref,
		    struct intel_timeline *tl,
		    struct i915_request *rq)
{
	struct i915_active_request *active;
	int err;

	lockdep_assert_held(&tl->mutex);

	/* Prevent reaping in case we malloc/wait while building the tree */
	err = i915_active_acquire(ref);
	if (err)
		return err;

	active = active_instance(ref, tl);
	if (!active) {
		err = -ENOMEM;
		goto out;
	}

	if (is_barrier(active)) { /* proto-node used by our idle barrier */
		/*
		 * This request is on the kernel_context timeline, and so
		 * we can use it to substitute for the pending idle-barrer
		 * request that we want to emit on the kernel_context.
		 */
		__active_del_barrier(ref, node_from_active(active));
		RCU_INIT_POINTER(active->request, NULL);
		INIT_LIST_HEAD(&active->link);
	} else {
		if (!i915_active_request_isset(active))
			atomic_inc(&ref->count);
	}
	GEM_BUG_ON(!atomic_read(&ref->count));
	__i915_active_request_set(active, rq);

out:
	i915_active_release(ref);
	return err;
}

int i915_active_acquire(struct i915_active *ref)
{
	int err;

	debug_active_assert(ref);
	if (atomic_add_unless(&ref->count, 1, 0))
		return 0;

	err = mutex_lock_interruptible(&ref->mutex);
	if (err)
		return err;

	if (!atomic_read(&ref->count) && ref->active)
		err = ref->active(ref);
	if (!err) {
		debug_active_activate(ref);
		atomic_inc(&ref->count);
	}

	mutex_unlock(&ref->mutex);

	return err;
}

void i915_active_release(struct i915_active *ref)
{
	debug_active_assert(ref);
	active_retire(ref);
}

static void __active_ungrab(struct i915_active *ref)
{
	clear_and_wake_up_bit(I915_ACTIVE_GRAB_BIT, &ref->flags);
}

bool i915_active_trygrab(struct i915_active *ref)
{
	debug_active_assert(ref);

	if (test_and_set_bit(I915_ACTIVE_GRAB_BIT, &ref->flags))
		return false;

	if (!atomic_add_unless(&ref->count, 1, 0)) {
		__active_ungrab(ref);
		return false;
	}

	return true;
}

void i915_active_ungrab(struct i915_active *ref)
{
	GEM_BUG_ON(!test_bit(I915_ACTIVE_GRAB_BIT, &ref->flags));

	active_retire(ref);
	__active_ungrab(ref);
}

int i915_active_wait(struct i915_active *ref)
{
	struct active_node *it, *n;
	int err;

	might_sleep();
	might_lock(&ref->mutex);

	if (i915_active_is_idle(ref))
		return 0;

	err = mutex_lock_interruptible(&ref->mutex);
	if (err)
		return err;

	if (!atomic_add_unless(&ref->count, 1, 0)) {
		mutex_unlock(&ref->mutex);
		return 0;
	}

	rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
		if (is_barrier(&it->base)) { /* unconnected idle-barrier */
			err = -EBUSY;
			break;
		}

		err = i915_active_request_retire(&it->base, BKL(ref));
		if (err)
			break;
	}

	__active_retire(ref);
	if (err)
		return err;

	if (wait_on_bit(&ref->flags, I915_ACTIVE_GRAB_BIT, TASK_KILLABLE))
		return -EINTR;

	if (!i915_active_is_idle(ref))
		return -EBUSY;

	return 0;
}

int i915_request_await_active_request(struct i915_request *rq,
				      struct i915_active_request *active)
{
	struct i915_request *barrier =
		i915_active_request_raw(active, &rq->i915->drm.struct_mutex);

	return barrier ? i915_request_await_dma_fence(rq, &barrier->fence) : 0;
}

int i915_request_await_active(struct i915_request *rq, struct i915_active *ref)
{
	struct active_node *it, *n;
	int err;

	if (RB_EMPTY_ROOT(&ref->tree))
		return 0;

	/* await allocates and so we need to avoid hitting the shrinker */
	err = i915_active_acquire(ref);
	if (err)
		return err;

	mutex_lock(&ref->mutex);
	rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
		err = i915_request_await_active_request(rq, &it->base);
		if (err)
			break;
	}
	mutex_unlock(&ref->mutex);

	i915_active_release(ref);
	return err;
}

#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
void i915_active_fini(struct i915_active *ref)
{
	debug_active_fini(ref);
	GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));
	GEM_BUG_ON(atomic_read(&ref->count));
	mutex_destroy(&ref->mutex);
}
#endif

static inline bool is_idle_barrier(struct active_node *node, u64 idx)
{
	return node->timeline == idx && !i915_active_request_isset(&node->base);
}

static struct active_node *reuse_idle_barrier(struct i915_active *ref, u64 idx)
{
	struct rb_node *prev, *p;

	if (RB_EMPTY_ROOT(&ref->tree))
		return NULL;

	mutex_lock(&ref->mutex);
	GEM_BUG_ON(i915_active_is_idle(ref));

	/*
	 * Try to reuse any existing barrier nodes already allocated for this
	 * i915_active, due to overlapping active phases there is likely a
	 * node kept alive (as we reuse before parking). We prefer to reuse
	 * completely idle barriers (less hassle in manipulating the llists),
	 * but otherwise any will do.
	 */
	if (ref->cache && is_idle_barrier(ref->cache, idx)) {
		p = &ref->cache->node;
		goto match;
	}

	prev = NULL;
	p = ref->tree.rb_node;
	while (p) {
		struct active_node *node =
			rb_entry(p, struct active_node, node);

		if (is_idle_barrier(node, idx))
			goto match;

		prev = p;
		if (node->timeline < idx)
			p = p->rb_right;
		else
			p = p->rb_left;
	}

	/*
	 * No quick match, but we did find the leftmost rb_node for the
	 * kernel_context. Walk the rb_tree in-order to see if there were
	 * any idle-barriers on this timeline that we missed, or just use
	 * the first pending barrier.
	 */
	for (p = prev; p; p = rb_next(p)) {
		struct active_node *node =
			rb_entry(p, struct active_node, node);
		struct intel_engine_cs *engine;

		if (node->timeline > idx)
			break;

		if (node->timeline < idx)
			continue;

		if (is_idle_barrier(node, idx))
			goto match;

		/*
		 * The list of pending barriers is protected by the
		 * kernel_context timeline, which notably we do not hold
		 * here. i915_request_add_active_barriers() may consume
		 * the barrier before we claim it, so we have to check
		 * for success.
		 */
		engine = __barrier_to_engine(node);
		smp_rmb(); /* serialise with add_active_barriers */
		if (is_barrier(&node->base) &&
		    ____active_del_barrier(ref, node, engine))
			goto match;
	}

	mutex_unlock(&ref->mutex);

	return NULL;

match:
	rb_erase(p, &ref->tree); /* Hide from waits and sibling allocations */
	if (p == &ref->cache->node)
		ref->cache = NULL;
	mutex_unlock(&ref->mutex);

	return rb_entry(p, struct active_node, node);
}

int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
					    struct intel_engine_cs *engine)
{
	struct drm_i915_private *i915 = engine->i915;
	intel_engine_mask_t tmp, mask = engine->mask;
	struct llist_node *pos, *next;
	int err;

	GEM_BUG_ON(!llist_empty(&ref->preallocated_barriers));

	/*
	 * Preallocate a node for each physical engine supporting the target
	 * engine (remember virtual engines have more than one sibling).
	 * We can then use the preallocated nodes in
	 * i915_active_acquire_barrier()
	 */
	for_each_engine_masked(engine, i915, mask, tmp) {
		u64 idx = engine->kernel_context->timeline->fence_context;
		struct active_node *node;

		node = reuse_idle_barrier(ref, idx);
		if (!node) {
			node = kmem_cache_alloc(global.slab_cache, GFP_KERNEL);
			if (!node) {
				err = ENOMEM;
				goto unwind;
			}

#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
			node->base.lock =
				&engine->kernel_context->timeline->mutex;
#endif
			RCU_INIT_POINTER(node->base.request, NULL);
			node->base.retire = node_retire;
			node->timeline = idx;
			node->ref = ref;
		}

		if (!i915_active_request_isset(&node->base)) {
			/*
			 * Mark this as being *our* unconnected proto-node.
			 *
			 * Since this node is not in any list, and we have
			 * decoupled it from the rbtree, we can reuse the
			 * request to indicate this is an idle-barrier node
			 * and then we can use the rb_node and list pointers
			 * for our tracking of the pending barrier.
			 */
			RCU_INIT_POINTER(node->base.request, ERR_PTR(-EAGAIN));
			node->base.link.prev = (void *)engine;
			atomic_inc(&ref->count);
		}

		GEM_BUG_ON(barrier_to_engine(node) != engine);
		llist_add(barrier_to_ll(node), &ref->preallocated_barriers);
		intel_engine_pm_get(engine);
	}

	return 0;

unwind:
	llist_for_each_safe(pos, next, take_preallocated_barriers(ref)) {
		struct active_node *node = barrier_from_ll(pos);

		atomic_dec(&ref->count);
		intel_engine_pm_put(barrier_to_engine(node));

		kmem_cache_free(global.slab_cache, node);
	}
	return err;
}

void i915_active_acquire_barrier(struct i915_active *ref)
{
	struct llist_node *pos, *next;

	GEM_BUG_ON(i915_active_is_idle(ref));

	/*
	 * Transfer the list of preallocated barriers into the
	 * i915_active rbtree, but only as proto-nodes. They will be
	 * populated by i915_request_add_active_barriers() to point to the
	 * request that will eventually release them.
	 */
	mutex_lock_nested(&ref->mutex, SINGLE_DEPTH_NESTING);
	llist_for_each_safe(pos, next, take_preallocated_barriers(ref)) {
		struct active_node *node = barrier_from_ll(pos);
		struct intel_engine_cs *engine = barrier_to_engine(node);
		struct rb_node **p, *parent;

		parent = NULL;
		p = &ref->tree.rb_node;
		while (*p) {
			struct active_node *it;

			parent = *p;

			it = rb_entry(parent, struct active_node, node);
			if (it->timeline < node->timeline)
				p = &parent->rb_right;
			else
				p = &parent->rb_left;
		}
		rb_link_node(&node->node, parent, p);
		rb_insert_color(&node->node, &ref->tree);

		llist_add(barrier_to_ll(node), &engine->barrier_tasks);
		intel_engine_pm_put(engine);
	}
	mutex_unlock(&ref->mutex);
}

void i915_request_add_active_barriers(struct i915_request *rq)
{
	struct intel_engine_cs *engine = rq->engine;
	struct llist_node *node, *next;

	GEM_BUG_ON(intel_engine_is_virtual(engine));
	GEM_BUG_ON(rq->timeline != engine->kernel_context->timeline);

	/*
	 * Attach the list of proto-fences to the in-flight request such
	 * that the parent i915_active will be released when this request
	 * is retired.
	 */
	llist_for_each_safe(node, next, llist_del_all(&engine->barrier_tasks)) {
		RCU_INIT_POINTER(barrier_from_ll(node)->base.request, rq);
		smp_wmb(); /* serialise with reuse_idle_barrier */
		list_add_tail((struct list_head *)node, &rq->active_list);
	}
}

int i915_active_request_set(struct i915_active_request *active,
			    struct i915_request *rq)
{
	int err;

#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
	lockdep_assert_held(active->lock);
#endif

	/* Must maintain ordering wrt previous active requests */
	err = i915_request_await_active_request(rq, active);
	if (err)
		return err;

	__i915_active_request_set(active, rq);
	return 0;
}

void i915_active_retire_noop(struct i915_active_request *active,
			     struct i915_request *request)
{
	/* Space left intentionally blank */
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/i915_active.c"
#endif

static void i915_global_active_shrink(void)
{
	kmem_cache_shrink(global.slab_cache);
}

static void i915_global_active_exit(void)
{
	kmem_cache_destroy(global.slab_cache);
}

static struct i915_global_active global = { {
	.shrink = i915_global_active_shrink,
	.exit = i915_global_active_exit,
} };

int __init i915_global_active_init(void)
{
	global.slab_cache = KMEM_CACHE(active_node, SLAB_HWCACHE_ALIGN);
	if (!global.slab_cache)
		return -ENOMEM;

	i915_global_register(&global.base);
	return 0;
}