]> Git Repo - linux.git/blob - drivers/gpu/drm/i915/i915_active.c
Merge tag 'amd-drm-next-6.5-2023-06-09' of https://gitlab.freedesktop.org/agd5f/linux...
[linux.git] / drivers / gpu / drm / i915 / i915_active.c
1 /*
2  * SPDX-License-Identifier: MIT
3  *
4  * Copyright © 2019 Intel Corporation
5  */
6
7 #include <linux/debugobjects.h>
8
9 #include "gt/intel_context.h"
10 #include "gt/intel_engine_heartbeat.h"
11 #include "gt/intel_engine_pm.h"
12 #include "gt/intel_ring.h"
13
14 #include "i915_drv.h"
15 #include "i915_active.h"
16
17 /*
18  * Active refs memory management
19  *
20  * To be more economical with memory, we reap all the i915_active trees as
21  * they idle (when we know the active requests are inactive) and allocate the
22  * nodes from a local slab cache to hopefully reduce the fragmentation.
23  */
24 static struct kmem_cache *slab_cache;
25
26 struct active_node {
27         struct rb_node node;
28         struct i915_active_fence base;
29         struct i915_active *ref;
30         u64 timeline;
31 };
32
33 #define fetch_node(x) rb_entry(READ_ONCE(x), typeof(struct active_node), node)
34
35 static inline struct active_node *
36 node_from_active(struct i915_active_fence *active)
37 {
38         return container_of(active, struct active_node, base);
39 }
40
41 #define take_preallocated_barriers(x) llist_del_all(&(x)->preallocated_barriers)
42
43 static inline bool is_barrier(const struct i915_active_fence *active)
44 {
45         return IS_ERR(rcu_access_pointer(active->fence));
46 }
47
48 static inline struct llist_node *barrier_to_ll(struct active_node *node)
49 {
50         GEM_BUG_ON(!is_barrier(&node->base));
51         return (struct llist_node *)&node->base.cb.node;
52 }
53
54 static inline struct intel_engine_cs *
55 __barrier_to_engine(struct active_node *node)
56 {
57         return (struct intel_engine_cs *)READ_ONCE(node->base.cb.node.prev);
58 }
59
60 static inline struct intel_engine_cs *
61 barrier_to_engine(struct active_node *node)
62 {
63         GEM_BUG_ON(!is_barrier(&node->base));
64         return __barrier_to_engine(node);
65 }
66
67 static inline struct active_node *barrier_from_ll(struct llist_node *x)
68 {
69         return container_of((struct list_head *)x,
70                             struct active_node, base.cb.node);
71 }
72
73 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM) && IS_ENABLED(CONFIG_DEBUG_OBJECTS)
74
75 static void *active_debug_hint(void *addr)
76 {
77         struct i915_active *ref = addr;
78
79         return (void *)ref->active ?: (void *)ref->retire ?: (void *)ref;
80 }
81
82 static const struct debug_obj_descr active_debug_desc = {
83         .name = "i915_active",
84         .debug_hint = active_debug_hint,
85 };
86
87 static void debug_active_init(struct i915_active *ref)
88 {
89         debug_object_init(ref, &active_debug_desc);
90 }
91
92 static void debug_active_activate(struct i915_active *ref)
93 {
94         lockdep_assert_held(&ref->tree_lock);
95         debug_object_activate(ref, &active_debug_desc);
96 }
97
98 static void debug_active_deactivate(struct i915_active *ref)
99 {
100         lockdep_assert_held(&ref->tree_lock);
101         if (!atomic_read(&ref->count)) /* after the last dec */
102                 debug_object_deactivate(ref, &active_debug_desc);
103 }
104
105 static void debug_active_fini(struct i915_active *ref)
106 {
107         debug_object_free(ref, &active_debug_desc);
108 }
109
110 static void debug_active_assert(struct i915_active *ref)
111 {
112         debug_object_assert_init(ref, &active_debug_desc);
113 }
114
115 #else
116
117 static inline void debug_active_init(struct i915_active *ref) { }
118 static inline void debug_active_activate(struct i915_active *ref) { }
119 static inline void debug_active_deactivate(struct i915_active *ref) { }
120 static inline void debug_active_fini(struct i915_active *ref) { }
121 static inline void debug_active_assert(struct i915_active *ref) { }
122
123 #endif
124
125 static void
126 __active_retire(struct i915_active *ref)
127 {
128         struct rb_root root = RB_ROOT;
129         struct active_node *it, *n;
130         unsigned long flags;
131
132         GEM_BUG_ON(i915_active_is_idle(ref));
133
134         /* return the unused nodes to our slabcache -- flushing the allocator */
135         if (!atomic_dec_and_lock_irqsave(&ref->count, &ref->tree_lock, flags))
136                 return;
137
138         GEM_BUG_ON(rcu_access_pointer(ref->excl.fence));
139         debug_active_deactivate(ref);
140
141         /* Even if we have not used the cache, we may still have a barrier */
142         if (!ref->cache)
143                 ref->cache = fetch_node(ref->tree.rb_node);
144
145         /* Keep the MRU cached node for reuse */
146         if (ref->cache) {
147                 /* Discard all other nodes in the tree */
148                 rb_erase(&ref->cache->node, &ref->tree);
149                 root = ref->tree;
150
151                 /* Rebuild the tree with only the cached node */
152                 rb_link_node(&ref->cache->node, NULL, &ref->tree.rb_node);
153                 rb_insert_color(&ref->cache->node, &ref->tree);
154                 GEM_BUG_ON(ref->tree.rb_node != &ref->cache->node);
155
156                 /* Make the cached node available for reuse with any timeline */
157                 ref->cache->timeline = 0; /* needs cmpxchg(u64) */
158         }
159
160         spin_unlock_irqrestore(&ref->tree_lock, flags);
161
162         /* After the final retire, the entire struct may be freed */
163         if (ref->retire)
164                 ref->retire(ref);
165
166         /* ... except if you wait on it, you must manage your own references! */
167         wake_up_var(ref);
168
169         /* Finally free the discarded timeline tree  */
170         rbtree_postorder_for_each_entry_safe(it, n, &root, node) {
171                 GEM_BUG_ON(i915_active_fence_isset(&it->base));
172                 kmem_cache_free(slab_cache, it);
173         }
174 }
175
176 static void
177 active_work(struct work_struct *wrk)
178 {
179         struct i915_active *ref = container_of(wrk, typeof(*ref), work);
180
181         GEM_BUG_ON(!atomic_read(&ref->count));
182         if (atomic_add_unless(&ref->count, -1, 1))
183                 return;
184
185         __active_retire(ref);
186 }
187
188 static void
189 active_retire(struct i915_active *ref)
190 {
191         GEM_BUG_ON(!atomic_read(&ref->count));
192         if (atomic_add_unless(&ref->count, -1, 1))
193                 return;
194
195         if (ref->flags & I915_ACTIVE_RETIRE_SLEEPS) {
196                 queue_work(system_unbound_wq, &ref->work);
197                 return;
198         }
199
200         __active_retire(ref);
201 }
202
203 static inline struct dma_fence **
204 __active_fence_slot(struct i915_active_fence *active)
205 {
206         return (struct dma_fence ** __force)&active->fence;
207 }
208
209 static inline bool
210 active_fence_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
211 {
212         struct i915_active_fence *active =
213                 container_of(cb, typeof(*active), cb);
214
215         return cmpxchg(__active_fence_slot(active), fence, NULL) == fence;
216 }
217
218 static void
219 node_retire(struct dma_fence *fence, struct dma_fence_cb *cb)
220 {
221         if (active_fence_cb(fence, cb))
222                 active_retire(container_of(cb, struct active_node, base.cb)->ref);
223 }
224
225 static void
226 excl_retire(struct dma_fence *fence, struct dma_fence_cb *cb)
227 {
228         if (active_fence_cb(fence, cb))
229                 active_retire(container_of(cb, struct i915_active, excl.cb));
230 }
231
232 static struct active_node *__active_lookup(struct i915_active *ref, u64 idx)
233 {
234         struct active_node *it;
235
236         GEM_BUG_ON(idx == 0); /* 0 is the unordered timeline, rsvd for cache */
237
238         /*
239          * We track the most recently used timeline to skip a rbtree search
240          * for the common case, under typical loads we never need the rbtree
241          * at all. We can reuse the last slot if it is empty, that is
242          * after the previous activity has been retired, or if it matches the
243          * current timeline.
244          */
245         it = READ_ONCE(ref->cache);
246         if (it) {
247                 u64 cached = READ_ONCE(it->timeline);
248
249                 /* Once claimed, this slot will only belong to this idx */
250                 if (cached == idx)
251                         return it;
252
253                 /*
254                  * An unclaimed cache [.timeline=0] can only be claimed once.
255                  *
256                  * If the value is already non-zero, some other thread has
257                  * claimed the cache and we know that is does not match our
258                  * idx. If, and only if, the timeline is currently zero is it
259                  * worth competing to claim it atomically for ourselves (for
260                  * only the winner of that race will cmpxchg return the old
261                  * value of 0).
262                  */
263                 if (!cached && !cmpxchg64(&it->timeline, 0, idx))
264                         return it;
265         }
266
267         BUILD_BUG_ON(offsetof(typeof(*it), node));
268
269         /* While active, the tree can only be built; not destroyed */
270         GEM_BUG_ON(i915_active_is_idle(ref));
271
272         it = fetch_node(ref->tree.rb_node);
273         while (it) {
274                 if (it->timeline < idx) {
275                         it = fetch_node(it->node.rb_right);
276                 } else if (it->timeline > idx) {
277                         it = fetch_node(it->node.rb_left);
278                 } else {
279                         WRITE_ONCE(ref->cache, it);
280                         break;
281                 }
282         }
283
284         /* NB: If the tree rotated beneath us, we may miss our target. */
285         return it;
286 }
287
288 static struct i915_active_fence *
289 active_instance(struct i915_active *ref, u64 idx)
290 {
291         struct active_node *node;
292         struct rb_node **p, *parent;
293
294         node = __active_lookup(ref, idx);
295         if (likely(node))
296                 return &node->base;
297
298         spin_lock_irq(&ref->tree_lock);
299         GEM_BUG_ON(i915_active_is_idle(ref));
300
301         parent = NULL;
302         p = &ref->tree.rb_node;
303         while (*p) {
304                 parent = *p;
305
306                 node = rb_entry(parent, struct active_node, node);
307                 if (node->timeline == idx)
308                         goto out;
309
310                 if (node->timeline < idx)
311                         p = &parent->rb_right;
312                 else
313                         p = &parent->rb_left;
314         }
315
316         /*
317          * XXX: We should preallocate this before i915_active_ref() is ever
318          *  called, but we cannot call into fs_reclaim() anyway, so use GFP_ATOMIC.
319          */
320         node = kmem_cache_alloc(slab_cache, GFP_ATOMIC);
321         if (!node)
322                 goto out;
323
324         __i915_active_fence_init(&node->base, NULL, node_retire);
325         node->ref = ref;
326         node->timeline = idx;
327
328         rb_link_node(&node->node, parent, p);
329         rb_insert_color(&node->node, &ref->tree);
330
331 out:
332         WRITE_ONCE(ref->cache, node);
333         spin_unlock_irq(&ref->tree_lock);
334
335         return &node->base;
336 }
337
338 void __i915_active_init(struct i915_active *ref,
339                         int (*active)(struct i915_active *ref),
340                         void (*retire)(struct i915_active *ref),
341                         unsigned long flags,
342                         struct lock_class_key *mkey,
343                         struct lock_class_key *wkey)
344 {
345         debug_active_init(ref);
346
347         ref->flags = flags;
348         ref->active = active;
349         ref->retire = retire;
350
351         spin_lock_init(&ref->tree_lock);
352         ref->tree = RB_ROOT;
353         ref->cache = NULL;
354
355         init_llist_head(&ref->preallocated_barriers);
356         atomic_set(&ref->count, 0);
357         __mutex_init(&ref->mutex, "i915_active", mkey);
358         __i915_active_fence_init(&ref->excl, NULL, excl_retire);
359         INIT_WORK(&ref->work, active_work);
360 #if IS_ENABLED(CONFIG_LOCKDEP)
361         lockdep_init_map(&ref->work.lockdep_map, "i915_active.work", wkey, 0);
362 #endif
363 }
364
365 static bool ____active_del_barrier(struct i915_active *ref,
366                                    struct active_node *node,
367                                    struct intel_engine_cs *engine)
368
369 {
370         struct llist_node *head = NULL, *tail = NULL;
371         struct llist_node *pos, *next;
372
373         GEM_BUG_ON(node->timeline != engine->kernel_context->timeline->fence_context);
374
375         /*
376          * Rebuild the llist excluding our node. We may perform this
377          * outside of the kernel_context timeline mutex and so someone
378          * else may be manipulating the engine->barrier_tasks, in
379          * which case either we or they will be upset :)
380          *
381          * A second __active_del_barrier() will report failure to claim
382          * the active_node and the caller will just shrug and know not to
383          * claim ownership of its node.
384          *
385          * A concurrent i915_request_add_active_barriers() will miss adding
386          * any of the tasks, but we will try again on the next -- and since
387          * we are actively using the barrier, we know that there will be
388          * at least another opportunity when we idle.
389          */
390         llist_for_each_safe(pos, next, llist_del_all(&engine->barrier_tasks)) {
391                 if (node == barrier_from_ll(pos)) {
392                         node = NULL;
393                         continue;
394                 }
395
396                 pos->next = head;
397                 head = pos;
398                 if (!tail)
399                         tail = pos;
400         }
401         if (head)
402                 llist_add_batch(head, tail, &engine->barrier_tasks);
403
404         return !node;
405 }
406
407 static bool
408 __active_del_barrier(struct i915_active *ref, struct active_node *node)
409 {
410         return ____active_del_barrier(ref, node, barrier_to_engine(node));
411 }
412
413 static bool
414 replace_barrier(struct i915_active *ref, struct i915_active_fence *active)
415 {
416         if (!is_barrier(active)) /* proto-node used by our idle barrier? */
417                 return false;
418
419         /*
420          * This request is on the kernel_context timeline, and so
421          * we can use it to substitute for the pending idle-barrer
422          * request that we want to emit on the kernel_context.
423          */
424         return __active_del_barrier(ref, node_from_active(active));
425 }
426
427 int i915_active_add_request(struct i915_active *ref, struct i915_request *rq)
428 {
429         u64 idx = i915_request_timeline(rq)->fence_context;
430         struct dma_fence *fence = &rq->fence;
431         struct i915_active_fence *active;
432         int err;
433
434         /* Prevent reaping in case we malloc/wait while building the tree */
435         err = i915_active_acquire(ref);
436         if (err)
437                 return err;
438
439         do {
440                 active = active_instance(ref, idx);
441                 if (!active) {
442                         err = -ENOMEM;
443                         goto out;
444                 }
445
446                 if (replace_barrier(ref, active)) {
447                         RCU_INIT_POINTER(active->fence, NULL);
448                         atomic_dec(&ref->count);
449                 }
450         } while (unlikely(is_barrier(active)));
451
452         if (!__i915_active_fence_set(active, fence))
453                 __i915_active_acquire(ref);
454
455 out:
456         i915_active_release(ref);
457         return err;
458 }
459
460 static struct dma_fence *
461 __i915_active_set_fence(struct i915_active *ref,
462                         struct i915_active_fence *active,
463                         struct dma_fence *fence)
464 {
465         struct dma_fence *prev;
466
467         if (replace_barrier(ref, active)) {
468                 RCU_INIT_POINTER(active->fence, fence);
469                 return NULL;
470         }
471
472         rcu_read_lock();
473         prev = __i915_active_fence_set(active, fence);
474         if (prev)
475                 prev = dma_fence_get_rcu(prev);
476         else
477                 __i915_active_acquire(ref);
478         rcu_read_unlock();
479
480         return prev;
481 }
482
483 struct dma_fence *
484 i915_active_set_exclusive(struct i915_active *ref, struct dma_fence *f)
485 {
486         /* We expect the caller to manage the exclusive timeline ordering */
487         return __i915_active_set_fence(ref, &ref->excl, f);
488 }
489
490 bool i915_active_acquire_if_busy(struct i915_active *ref)
491 {
492         debug_active_assert(ref);
493         return atomic_add_unless(&ref->count, 1, 0);
494 }
495
496 static void __i915_active_activate(struct i915_active *ref)
497 {
498         spin_lock_irq(&ref->tree_lock); /* __active_retire() */
499         if (!atomic_fetch_inc(&ref->count))
500                 debug_active_activate(ref);
501         spin_unlock_irq(&ref->tree_lock);
502 }
503
504 int i915_active_acquire(struct i915_active *ref)
505 {
506         int err;
507
508         if (i915_active_acquire_if_busy(ref))
509                 return 0;
510
511         if (!ref->active) {
512                 __i915_active_activate(ref);
513                 return 0;
514         }
515
516         err = mutex_lock_interruptible(&ref->mutex);
517         if (err)
518                 return err;
519
520         if (likely(!i915_active_acquire_if_busy(ref))) {
521                 err = ref->active(ref);
522                 if (!err)
523                         __i915_active_activate(ref);
524         }
525
526         mutex_unlock(&ref->mutex);
527
528         return err;
529 }
530
531 int i915_active_acquire_for_context(struct i915_active *ref, u64 idx)
532 {
533         struct i915_active_fence *active;
534         int err;
535
536         err = i915_active_acquire(ref);
537         if (err)
538                 return err;
539
540         active = active_instance(ref, idx);
541         if (!active) {
542                 i915_active_release(ref);
543                 return -ENOMEM;
544         }
545
546         return 0; /* return with active ref */
547 }
548
549 void i915_active_release(struct i915_active *ref)
550 {
551         debug_active_assert(ref);
552         active_retire(ref);
553 }
554
555 static void enable_signaling(struct i915_active_fence *active)
556 {
557         struct dma_fence *fence;
558
559         if (unlikely(is_barrier(active)))
560                 return;
561
562         fence = i915_active_fence_get(active);
563         if (!fence)
564                 return;
565
566         dma_fence_enable_sw_signaling(fence);
567         dma_fence_put(fence);
568 }
569
570 static int flush_barrier(struct active_node *it)
571 {
572         struct intel_engine_cs *engine;
573
574         if (likely(!is_barrier(&it->base)))
575                 return 0;
576
577         engine = __barrier_to_engine(it);
578         smp_rmb(); /* serialise with add_active_barriers */
579         if (!is_barrier(&it->base))
580                 return 0;
581
582         return intel_engine_flush_barriers(engine);
583 }
584
585 static int flush_lazy_signals(struct i915_active *ref)
586 {
587         struct active_node *it, *n;
588         int err = 0;
589
590         enable_signaling(&ref->excl);
591         rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
592                 err = flush_barrier(it); /* unconnected idle barrier? */
593                 if (err)
594                         break;
595
596                 enable_signaling(&it->base);
597         }
598
599         return err;
600 }
601
602 int __i915_active_wait(struct i915_active *ref, int state)
603 {
604         might_sleep();
605
606         /* Any fence added after the wait begins will not be auto-signaled */
607         if (i915_active_acquire_if_busy(ref)) {
608                 int err;
609
610                 err = flush_lazy_signals(ref);
611                 i915_active_release(ref);
612                 if (err)
613                         return err;
614
615                 if (___wait_var_event(ref, i915_active_is_idle(ref),
616                                       state, 0, 0, schedule()))
617                         return -EINTR;
618         }
619
620         /*
621          * After the wait is complete, the caller may free the active.
622          * We have to flush any concurrent retirement before returning.
623          */
624         flush_work(&ref->work);
625         return 0;
626 }
627
628 static int __await_active(struct i915_active_fence *active,
629                           int (*fn)(void *arg, struct dma_fence *fence),
630                           void *arg)
631 {
632         struct dma_fence *fence;
633
634         if (is_barrier(active)) /* XXX flush the barrier? */
635                 return 0;
636
637         fence = i915_active_fence_get(active);
638         if (fence) {
639                 int err;
640
641                 err = fn(arg, fence);
642                 dma_fence_put(fence);
643                 if (err < 0)
644                         return err;
645         }
646
647         return 0;
648 }
649
650 struct wait_barrier {
651         struct wait_queue_entry base;
652         struct i915_active *ref;
653 };
654
655 static int
656 barrier_wake(wait_queue_entry_t *wq, unsigned int mode, int flags, void *key)
657 {
658         struct wait_barrier *wb = container_of(wq, typeof(*wb), base);
659
660         if (i915_active_is_idle(wb->ref)) {
661                 list_del(&wq->entry);
662                 i915_sw_fence_complete(wq->private);
663                 kfree(wq);
664         }
665
666         return 0;
667 }
668
669 static int __await_barrier(struct i915_active *ref, struct i915_sw_fence *fence)
670 {
671         struct wait_barrier *wb;
672
673         wb = kmalloc(sizeof(*wb), GFP_KERNEL);
674         if (unlikely(!wb))
675                 return -ENOMEM;
676
677         GEM_BUG_ON(i915_active_is_idle(ref));
678         if (!i915_sw_fence_await(fence)) {
679                 kfree(wb);
680                 return -EINVAL;
681         }
682
683         wb->base.flags = 0;
684         wb->base.func = barrier_wake;
685         wb->base.private = fence;
686         wb->ref = ref;
687
688         add_wait_queue(__var_waitqueue(ref), &wb->base);
689         return 0;
690 }
691
692 static int await_active(struct i915_active *ref,
693                         unsigned int flags,
694                         int (*fn)(void *arg, struct dma_fence *fence),
695                         void *arg, struct i915_sw_fence *barrier)
696 {
697         int err = 0;
698
699         if (!i915_active_acquire_if_busy(ref))
700                 return 0;
701
702         if (flags & I915_ACTIVE_AWAIT_EXCL &&
703             rcu_access_pointer(ref->excl.fence)) {
704                 err = __await_active(&ref->excl, fn, arg);
705                 if (err)
706                         goto out;
707         }
708
709         if (flags & I915_ACTIVE_AWAIT_ACTIVE) {
710                 struct active_node *it, *n;
711
712                 rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
713                         err = __await_active(&it->base, fn, arg);
714                         if (err)
715                                 goto out;
716                 }
717         }
718
719         if (flags & I915_ACTIVE_AWAIT_BARRIER) {
720                 err = flush_lazy_signals(ref);
721                 if (err)
722                         goto out;
723
724                 err = __await_barrier(ref, barrier);
725                 if (err)
726                         goto out;
727         }
728
729 out:
730         i915_active_release(ref);
731         return err;
732 }
733
734 static int rq_await_fence(void *arg, struct dma_fence *fence)
735 {
736         return i915_request_await_dma_fence(arg, fence);
737 }
738
739 int i915_request_await_active(struct i915_request *rq,
740                               struct i915_active *ref,
741                               unsigned int flags)
742 {
743         return await_active(ref, flags, rq_await_fence, rq, &rq->submit);
744 }
745
746 static int sw_await_fence(void *arg, struct dma_fence *fence)
747 {
748         return i915_sw_fence_await_dma_fence(arg, fence, 0,
749                                              GFP_NOWAIT | __GFP_NOWARN);
750 }
751
752 int i915_sw_fence_await_active(struct i915_sw_fence *fence,
753                                struct i915_active *ref,
754                                unsigned int flags)
755 {
756         return await_active(ref, flags, sw_await_fence, fence, fence);
757 }
758
759 void i915_active_fini(struct i915_active *ref)
760 {
761         debug_active_fini(ref);
762         GEM_BUG_ON(atomic_read(&ref->count));
763         GEM_BUG_ON(work_pending(&ref->work));
764         mutex_destroy(&ref->mutex);
765
766         if (ref->cache)
767                 kmem_cache_free(slab_cache, ref->cache);
768 }
769
770 static inline bool is_idle_barrier(struct active_node *node, u64 idx)
771 {
772         return node->timeline == idx && !i915_active_fence_isset(&node->base);
773 }
774
775 static struct active_node *reuse_idle_barrier(struct i915_active *ref, u64 idx)
776 {
777         struct rb_node *prev, *p;
778
779         if (RB_EMPTY_ROOT(&ref->tree))
780                 return NULL;
781
782         GEM_BUG_ON(i915_active_is_idle(ref));
783
784         /*
785          * Try to reuse any existing barrier nodes already allocated for this
786          * i915_active, due to overlapping active phases there is likely a
787          * node kept alive (as we reuse before parking). We prefer to reuse
788          * completely idle barriers (less hassle in manipulating the llists),
789          * but otherwise any will do.
790          */
791         if (ref->cache && is_idle_barrier(ref->cache, idx)) {
792                 p = &ref->cache->node;
793                 goto match;
794         }
795
796         prev = NULL;
797         p = ref->tree.rb_node;
798         while (p) {
799                 struct active_node *node =
800                         rb_entry(p, struct active_node, node);
801
802                 if (is_idle_barrier(node, idx))
803                         goto match;
804
805                 prev = p;
806                 if (node->timeline < idx)
807                         p = READ_ONCE(p->rb_right);
808                 else
809                         p = READ_ONCE(p->rb_left);
810         }
811
812         /*
813          * No quick match, but we did find the leftmost rb_node for the
814          * kernel_context. Walk the rb_tree in-order to see if there were
815          * any idle-barriers on this timeline that we missed, or just use
816          * the first pending barrier.
817          */
818         for (p = prev; p; p = rb_next(p)) {
819                 struct active_node *node =
820                         rb_entry(p, struct active_node, node);
821                 struct intel_engine_cs *engine;
822
823                 if (node->timeline > idx)
824                         break;
825
826                 if (node->timeline < idx)
827                         continue;
828
829                 if (is_idle_barrier(node, idx))
830                         goto match;
831
832                 /*
833                  * The list of pending barriers is protected by the
834                  * kernel_context timeline, which notably we do not hold
835                  * here. i915_request_add_active_barriers() may consume
836                  * the barrier before we claim it, so we have to check
837                  * for success.
838                  */
839                 engine = __barrier_to_engine(node);
840                 smp_rmb(); /* serialise with add_active_barriers */
841                 if (is_barrier(&node->base) &&
842                     ____active_del_barrier(ref, node, engine))
843                         goto match;
844         }
845
846         return NULL;
847
848 match:
849         spin_lock_irq(&ref->tree_lock);
850         rb_erase(p, &ref->tree); /* Hide from waits and sibling allocations */
851         if (p == &ref->cache->node)
852                 WRITE_ONCE(ref->cache, NULL);
853         spin_unlock_irq(&ref->tree_lock);
854
855         return rb_entry(p, struct active_node, node);
856 }
857
858 int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
859                                             struct intel_engine_cs *engine)
860 {
861         intel_engine_mask_t tmp, mask = engine->mask;
862         struct llist_node *first = NULL, *last = NULL;
863         struct intel_gt *gt = engine->gt;
864
865         GEM_BUG_ON(i915_active_is_idle(ref));
866
867         /* Wait until the previous preallocation is completed */
868         while (!llist_empty(&ref->preallocated_barriers))
869                 cond_resched();
870
871         /*
872          * Preallocate a node for each physical engine supporting the target
873          * engine (remember virtual engines have more than one sibling).
874          * We can then use the preallocated nodes in
875          * i915_active_acquire_barrier()
876          */
877         GEM_BUG_ON(!mask);
878         for_each_engine_masked(engine, gt, mask, tmp) {
879                 u64 idx = engine->kernel_context->timeline->fence_context;
880                 struct llist_node *prev = first;
881                 struct active_node *node;
882
883                 rcu_read_lock();
884                 node = reuse_idle_barrier(ref, idx);
885                 rcu_read_unlock();
886                 if (!node) {
887                         node = kmem_cache_alloc(slab_cache, GFP_KERNEL);
888                         if (!node)
889                                 goto unwind;
890
891                         RCU_INIT_POINTER(node->base.fence, NULL);
892                         node->base.cb.func = node_retire;
893                         node->timeline = idx;
894                         node->ref = ref;
895                 }
896
897                 if (!i915_active_fence_isset(&node->base)) {
898                         /*
899                          * Mark this as being *our* unconnected proto-node.
900                          *
901                          * Since this node is not in any list, and we have
902                          * decoupled it from the rbtree, we can reuse the
903                          * request to indicate this is an idle-barrier node
904                          * and then we can use the rb_node and list pointers
905                          * for our tracking of the pending barrier.
906                          */
907                         RCU_INIT_POINTER(node->base.fence, ERR_PTR(-EAGAIN));
908                         node->base.cb.node.prev = (void *)engine;
909                         __i915_active_acquire(ref);
910                 }
911                 GEM_BUG_ON(rcu_access_pointer(node->base.fence) != ERR_PTR(-EAGAIN));
912
913                 GEM_BUG_ON(barrier_to_engine(node) != engine);
914                 first = barrier_to_ll(node);
915                 first->next = prev;
916                 if (!last)
917                         last = first;
918                 intel_engine_pm_get(engine);
919         }
920
921         GEM_BUG_ON(!llist_empty(&ref->preallocated_barriers));
922         llist_add_batch(first, last, &ref->preallocated_barriers);
923
924         return 0;
925
926 unwind:
927         while (first) {
928                 struct active_node *node = barrier_from_ll(first);
929
930                 first = first->next;
931
932                 atomic_dec(&ref->count);
933                 intel_engine_pm_put(barrier_to_engine(node));
934
935                 kmem_cache_free(slab_cache, node);
936         }
937         return -ENOMEM;
938 }
939
940 void i915_active_acquire_barrier(struct i915_active *ref)
941 {
942         struct llist_node *pos, *next;
943         unsigned long flags;
944
945         GEM_BUG_ON(i915_active_is_idle(ref));
946
947         /*
948          * Transfer the list of preallocated barriers into the
949          * i915_active rbtree, but only as proto-nodes. They will be
950          * populated by i915_request_add_active_barriers() to point to the
951          * request that will eventually release them.
952          */
953         llist_for_each_safe(pos, next, take_preallocated_barriers(ref)) {
954                 struct active_node *node = barrier_from_ll(pos);
955                 struct intel_engine_cs *engine = barrier_to_engine(node);
956                 struct rb_node **p, *parent;
957
958                 spin_lock_irqsave_nested(&ref->tree_lock, flags,
959                                          SINGLE_DEPTH_NESTING);
960                 parent = NULL;
961                 p = &ref->tree.rb_node;
962                 while (*p) {
963                         struct active_node *it;
964
965                         parent = *p;
966
967                         it = rb_entry(parent, struct active_node, node);
968                         if (it->timeline < node->timeline)
969                                 p = &parent->rb_right;
970                         else
971                                 p = &parent->rb_left;
972                 }
973                 rb_link_node(&node->node, parent, p);
974                 rb_insert_color(&node->node, &ref->tree);
975                 spin_unlock_irqrestore(&ref->tree_lock, flags);
976
977                 GEM_BUG_ON(!intel_engine_pm_is_awake(engine));
978                 llist_add(barrier_to_ll(node), &engine->barrier_tasks);
979                 intel_engine_pm_put_delay(engine, 2);
980         }
981 }
982
983 static struct dma_fence **ll_to_fence_slot(struct llist_node *node)
984 {
985         return __active_fence_slot(&barrier_from_ll(node)->base);
986 }
987
988 void i915_request_add_active_barriers(struct i915_request *rq)
989 {
990         struct intel_engine_cs *engine = rq->engine;
991         struct llist_node *node, *next;
992         unsigned long flags;
993
994         GEM_BUG_ON(!intel_context_is_barrier(rq->context));
995         GEM_BUG_ON(intel_engine_is_virtual(engine));
996         GEM_BUG_ON(i915_request_timeline(rq) != engine->kernel_context->timeline);
997
998         node = llist_del_all(&engine->barrier_tasks);
999         if (!node)
1000                 return;
1001         /*
1002          * Attach the list of proto-fences to the in-flight request such
1003          * that the parent i915_active will be released when this request
1004          * is retired.
1005          */
1006         spin_lock_irqsave(&rq->lock, flags);
1007         llist_for_each_safe(node, next, node) {
1008                 /* serialise with reuse_idle_barrier */
1009                 smp_store_mb(*ll_to_fence_slot(node), &rq->fence);
1010                 list_add_tail((struct list_head *)node, &rq->fence.cb_list);
1011         }
1012         spin_unlock_irqrestore(&rq->lock, flags);
1013 }
1014
1015 /*
1016  * __i915_active_fence_set: Update the last active fence along its timeline
1017  * @active: the active tracker
1018  * @fence: the new fence (under construction)
1019  *
1020  * Records the new @fence as the last active fence along its timeline in
1021  * this active tracker, moving the tracking callbacks from the previous
1022  * fence onto this one. Returns the previous fence (if not already completed),
1023  * which the caller must ensure is executed before the new fence. To ensure
1024  * that the order of fences within the timeline of the i915_active_fence is
1025  * understood, it should be locked by the caller.
1026  */
1027 struct dma_fence *
1028 __i915_active_fence_set(struct i915_active_fence *active,
1029                         struct dma_fence *fence)
1030 {
1031         struct dma_fence *prev;
1032         unsigned long flags;
1033
1034         if (fence == rcu_access_pointer(active->fence))
1035                 return fence;
1036
1037         GEM_BUG_ON(test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags));
1038
1039         /*
1040          * Consider that we have two threads arriving (A and B), with
1041          * C already resident as the active->fence.
1042          *
1043          * A does the xchg first, and so it sees C or NULL depending
1044          * on the timing of the interrupt handler. If it is NULL, the
1045          * previous fence must have been signaled and we know that
1046          * we are first on the timeline. If it is still present,
1047          * we acquire the lock on that fence and serialise with the interrupt
1048          * handler, in the process removing it from any future interrupt
1049          * callback. A will then wait on C before executing (if present).
1050          *
1051          * As B is second, it sees A as the previous fence and so waits for
1052          * it to complete its transition and takes over the occupancy for
1053          * itself -- remembering that it needs to wait on A before executing.
1054          *
1055          * Note the strong ordering of the timeline also provides consistent
1056          * nesting rules for the fence->lock; the inner lock is always the
1057          * older lock.
1058          */
1059         spin_lock_irqsave(fence->lock, flags);
1060         prev = xchg(__active_fence_slot(active), fence);
1061         if (prev) {
1062                 GEM_BUG_ON(prev == fence);
1063                 spin_lock_nested(prev->lock, SINGLE_DEPTH_NESTING);
1064                 __list_del_entry(&active->cb.node);
1065                 spin_unlock(prev->lock); /* serialise with prev->cb_list */
1066         }
1067         list_add_tail(&active->cb.node, &fence->cb_list);
1068         spin_unlock_irqrestore(fence->lock, flags);
1069
1070         return prev;
1071 }
1072
1073 int i915_active_fence_set(struct i915_active_fence *active,
1074                           struct i915_request *rq)
1075 {
1076         struct dma_fence *fence;
1077         int err = 0;
1078
1079         /* Must maintain timeline ordering wrt previous active requests */
1080         rcu_read_lock();
1081         fence = __i915_active_fence_set(active, &rq->fence);
1082         if (fence) /* but the previous fence may not belong to that timeline! */
1083                 fence = dma_fence_get_rcu(fence);
1084         rcu_read_unlock();
1085         if (fence) {
1086                 err = i915_request_await_dma_fence(rq, fence);
1087                 dma_fence_put(fence);
1088         }
1089
1090         return err;
1091 }
1092
1093 void i915_active_noop(struct dma_fence *fence, struct dma_fence_cb *cb)
1094 {
1095         active_fence_cb(fence, cb);
1096 }
1097
1098 struct auto_active {
1099         struct i915_active base;
1100         struct kref ref;
1101 };
1102
1103 struct i915_active *i915_active_get(struct i915_active *ref)
1104 {
1105         struct auto_active *aa = container_of(ref, typeof(*aa), base);
1106
1107         kref_get(&aa->ref);
1108         return &aa->base;
1109 }
1110
1111 static void auto_release(struct kref *ref)
1112 {
1113         struct auto_active *aa = container_of(ref, typeof(*aa), ref);
1114
1115         i915_active_fini(&aa->base);
1116         kfree(aa);
1117 }
1118
1119 void i915_active_put(struct i915_active *ref)
1120 {
1121         struct auto_active *aa = container_of(ref, typeof(*aa), base);
1122
1123         kref_put(&aa->ref, auto_release);
1124 }
1125
1126 static int auto_active(struct i915_active *ref)
1127 {
1128         i915_active_get(ref);
1129         return 0;
1130 }
1131
1132 static void auto_retire(struct i915_active *ref)
1133 {
1134         i915_active_put(ref);
1135 }
1136
1137 struct i915_active *i915_active_create(void)
1138 {
1139         struct auto_active *aa;
1140
1141         aa = kmalloc(sizeof(*aa), GFP_KERNEL);
1142         if (!aa)
1143                 return NULL;
1144
1145         kref_init(&aa->ref);
1146         i915_active_init(&aa->base, auto_active, auto_retire, 0);
1147
1148         return &aa->base;
1149 }
1150
1151 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
1152 #include "selftests/i915_active.c"
1153 #endif
1154
1155 void i915_active_module_exit(void)
1156 {
1157         kmem_cache_destroy(slab_cache);
1158 }
1159
1160 int __init i915_active_module_init(void)
1161 {
1162         slab_cache = KMEM_CACHE(active_node, SLAB_HWCACHE_ALIGN);
1163         if (!slab_cache)
1164                 return -ENOMEM;
1165
1166         return 0;
1167 }
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