Merge branch 'urgent-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6-microblaze.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 #include "i915_globals.h"
17
18 /*
19  * Active refs memory management
20  *
21  * To be more economical with memory, we reap all the i915_active trees as
22  * they idle (when we know the active requests are inactive) and allocate the
23  * nodes from a local slab cache to hopefully reduce the fragmentation.
24  */
25 static struct i915_global_active {
26         struct i915_global base;
27         struct kmem_cache *slab_cache;
28 } global;
29
30 struct active_node {
31         struct i915_active_fence base;
32         struct i915_active *ref;
33         struct rb_node node;
34         u64 timeline;
35 };
36
37 static inline struct active_node *
38 node_from_active(struct i915_active_fence *active)
39 {
40         return container_of(active, struct active_node, base);
41 }
42
43 #define take_preallocated_barriers(x) llist_del_all(&(x)->preallocated_barriers)
44
45 static inline bool is_barrier(const struct i915_active_fence *active)
46 {
47         return IS_ERR(rcu_access_pointer(active->fence));
48 }
49
50 static inline struct llist_node *barrier_to_ll(struct active_node *node)
51 {
52         GEM_BUG_ON(!is_barrier(&node->base));
53         return (struct llist_node *)&node->base.cb.node;
54 }
55
56 static inline struct intel_engine_cs *
57 __barrier_to_engine(struct active_node *node)
58 {
59         return (struct intel_engine_cs *)READ_ONCE(node->base.cb.node.prev);
60 }
61
62 static inline struct intel_engine_cs *
63 barrier_to_engine(struct active_node *node)
64 {
65         GEM_BUG_ON(!is_barrier(&node->base));
66         return __barrier_to_engine(node);
67 }
68
69 static inline struct active_node *barrier_from_ll(struct llist_node *x)
70 {
71         return container_of((struct list_head *)x,
72                             struct active_node, base.cb.node);
73 }
74
75 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM) && IS_ENABLED(CONFIG_DEBUG_OBJECTS)
76
77 static void *active_debug_hint(void *addr)
78 {
79         struct i915_active *ref = addr;
80
81         return (void *)ref->active ?: (void *)ref->retire ?: (void *)ref;
82 }
83
84 static struct debug_obj_descr active_debug_desc = {
85         .name = "i915_active",
86         .debug_hint = active_debug_hint,
87 };
88
89 static void debug_active_init(struct i915_active *ref)
90 {
91         debug_object_init(ref, &active_debug_desc);
92 }
93
94 static void debug_active_activate(struct i915_active *ref)
95 {
96         lockdep_assert_held(&ref->tree_lock);
97         if (!atomic_read(&ref->count)) /* before the first inc */
98                 debug_object_activate(ref, &active_debug_desc);
99 }
100
101 static void debug_active_deactivate(struct i915_active *ref)
102 {
103         lockdep_assert_held(&ref->tree_lock);
104         if (!atomic_read(&ref->count)) /* after the last dec */
105                 debug_object_deactivate(ref, &active_debug_desc);
106 }
107
108 static void debug_active_fini(struct i915_active *ref)
109 {
110         debug_object_free(ref, &active_debug_desc);
111 }
112
113 static void debug_active_assert(struct i915_active *ref)
114 {
115         debug_object_assert_init(ref, &active_debug_desc);
116 }
117
118 #else
119
120 static inline void debug_active_init(struct i915_active *ref) { }
121 static inline void debug_active_activate(struct i915_active *ref) { }
122 static inline void debug_active_deactivate(struct i915_active *ref) { }
123 static inline void debug_active_fini(struct i915_active *ref) { }
124 static inline void debug_active_assert(struct i915_active *ref) { }
125
126 #endif
127
128 static void
129 __active_retire(struct i915_active *ref)
130 {
131         struct active_node *it, *n;
132         struct rb_root root;
133         unsigned long flags;
134
135         GEM_BUG_ON(i915_active_is_idle(ref));
136
137         /* return the unused nodes to our slabcache -- flushing the allocator */
138         if (!atomic_dec_and_lock_irqsave(&ref->count, &ref->tree_lock, flags))
139                 return;
140
141         GEM_BUG_ON(rcu_access_pointer(ref->excl.fence));
142         debug_active_deactivate(ref);
143
144         root = ref->tree;
145         ref->tree = RB_ROOT;
146         ref->cache = NULL;
147
148         spin_unlock_irqrestore(&ref->tree_lock, flags);
149
150         /* After the final retire, the entire struct may be freed */
151         if (ref->retire)
152                 ref->retire(ref);
153
154         /* ... except if you wait on it, you must manage your own references! */
155         wake_up_var(ref);
156
157         rbtree_postorder_for_each_entry_safe(it, n, &root, node) {
158                 GEM_BUG_ON(i915_active_fence_isset(&it->base));
159                 kmem_cache_free(global.slab_cache, it);
160         }
161 }
162
163 static void
164 active_work(struct work_struct *wrk)
165 {
166         struct i915_active *ref = container_of(wrk, typeof(*ref), work);
167
168         GEM_BUG_ON(!atomic_read(&ref->count));
169         if (atomic_add_unless(&ref->count, -1, 1))
170                 return;
171
172         __active_retire(ref);
173 }
174
175 static void
176 active_retire(struct i915_active *ref)
177 {
178         GEM_BUG_ON(!atomic_read(&ref->count));
179         if (atomic_add_unless(&ref->count, -1, 1))
180                 return;
181
182         if (ref->flags & I915_ACTIVE_RETIRE_SLEEPS) {
183                 queue_work(system_unbound_wq, &ref->work);
184                 return;
185         }
186
187         __active_retire(ref);
188 }
189
190 static inline struct dma_fence **
191 __active_fence_slot(struct i915_active_fence *active)
192 {
193         return (struct dma_fence ** __force)&active->fence;
194 }
195
196 static inline bool
197 active_fence_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
198 {
199         struct i915_active_fence *active =
200                 container_of(cb, typeof(*active), cb);
201
202         return cmpxchg(__active_fence_slot(active), fence, NULL) == fence;
203 }
204
205 static void
206 node_retire(struct dma_fence *fence, struct dma_fence_cb *cb)
207 {
208         if (active_fence_cb(fence, cb))
209                 active_retire(container_of(cb, struct active_node, base.cb)->ref);
210 }
211
212 static void
213 excl_retire(struct dma_fence *fence, struct dma_fence_cb *cb)
214 {
215         if (active_fence_cb(fence, cb))
216                 active_retire(container_of(cb, struct i915_active, excl.cb));
217 }
218
219 static struct i915_active_fence *
220 active_instance(struct i915_active *ref, struct intel_timeline *tl)
221 {
222         struct active_node *node, *prealloc;
223         struct rb_node **p, *parent;
224         u64 idx = tl->fence_context;
225
226         /*
227          * We track the most recently used timeline to skip a rbtree search
228          * for the common case, under typical loads we never need the rbtree
229          * at all. We can reuse the last slot if it is empty, that is
230          * after the previous activity has been retired, or if it matches the
231          * current timeline.
232          */
233         node = READ_ONCE(ref->cache);
234         if (node && node->timeline == idx)
235                 return &node->base;
236
237         /* Preallocate a replacement, just in case */
238         prealloc = kmem_cache_alloc(global.slab_cache, GFP_KERNEL);
239         if (!prealloc)
240                 return NULL;
241
242         spin_lock_irq(&ref->tree_lock);
243         GEM_BUG_ON(i915_active_is_idle(ref));
244
245         parent = NULL;
246         p = &ref->tree.rb_node;
247         while (*p) {
248                 parent = *p;
249
250                 node = rb_entry(parent, struct active_node, node);
251                 if (node->timeline == idx) {
252                         kmem_cache_free(global.slab_cache, prealloc);
253                         goto out;
254                 }
255
256                 if (node->timeline < idx)
257                         p = &parent->rb_right;
258                 else
259                         p = &parent->rb_left;
260         }
261
262         node = prealloc;
263         __i915_active_fence_init(&node->base, NULL, node_retire);
264         node->ref = ref;
265         node->timeline = idx;
266
267         rb_link_node(&node->node, parent, p);
268         rb_insert_color(&node->node, &ref->tree);
269
270 out:
271         ref->cache = node;
272         spin_unlock_irq(&ref->tree_lock);
273
274         BUILD_BUG_ON(offsetof(typeof(*node), base));
275         return &node->base;
276 }
277
278 void __i915_active_init(struct i915_active *ref,
279                         int (*active)(struct i915_active *ref),
280                         void (*retire)(struct i915_active *ref),
281                         struct lock_class_key *mkey,
282                         struct lock_class_key *wkey)
283 {
284         unsigned long bits;
285
286         debug_active_init(ref);
287
288         ref->flags = 0;
289         ref->active = active;
290         ref->retire = ptr_unpack_bits(retire, &bits, 2);
291         if (bits & I915_ACTIVE_MAY_SLEEP)
292                 ref->flags |= I915_ACTIVE_RETIRE_SLEEPS;
293
294         spin_lock_init(&ref->tree_lock);
295         ref->tree = RB_ROOT;
296         ref->cache = NULL;
297
298         init_llist_head(&ref->preallocated_barriers);
299         atomic_set(&ref->count, 0);
300         __mutex_init(&ref->mutex, "i915_active", mkey);
301         __i915_active_fence_init(&ref->excl, NULL, excl_retire);
302         INIT_WORK(&ref->work, active_work);
303 #if IS_ENABLED(CONFIG_LOCKDEP)
304         lockdep_init_map(&ref->work.lockdep_map, "i915_active.work", wkey, 0);
305 #endif
306 }
307
308 static bool ____active_del_barrier(struct i915_active *ref,
309                                    struct active_node *node,
310                                    struct intel_engine_cs *engine)
311
312 {
313         struct llist_node *head = NULL, *tail = NULL;
314         struct llist_node *pos, *next;
315
316         GEM_BUG_ON(node->timeline != engine->kernel_context->timeline->fence_context);
317
318         /*
319          * Rebuild the llist excluding our node. We may perform this
320          * outside of the kernel_context timeline mutex and so someone
321          * else may be manipulating the engine->barrier_tasks, in
322          * which case either we or they will be upset :)
323          *
324          * A second __active_del_barrier() will report failure to claim
325          * the active_node and the caller will just shrug and know not to
326          * claim ownership of its node.
327          *
328          * A concurrent i915_request_add_active_barriers() will miss adding
329          * any of the tasks, but we will try again on the next -- and since
330          * we are actively using the barrier, we know that there will be
331          * at least another opportunity when we idle.
332          */
333         llist_for_each_safe(pos, next, llist_del_all(&engine->barrier_tasks)) {
334                 if (node == barrier_from_ll(pos)) {
335                         node = NULL;
336                         continue;
337                 }
338
339                 pos->next = head;
340                 head = pos;
341                 if (!tail)
342                         tail = pos;
343         }
344         if (head)
345                 llist_add_batch(head, tail, &engine->barrier_tasks);
346
347         return !node;
348 }
349
350 static bool
351 __active_del_barrier(struct i915_active *ref, struct active_node *node)
352 {
353         return ____active_del_barrier(ref, node, barrier_to_engine(node));
354 }
355
356 int i915_active_ref(struct i915_active *ref,
357                     struct intel_timeline *tl,
358                     struct dma_fence *fence)
359 {
360         struct i915_active_fence *active;
361         int err;
362
363         lockdep_assert_held(&tl->mutex);
364
365         /* Prevent reaping in case we malloc/wait while building the tree */
366         err = i915_active_acquire(ref);
367         if (err)
368                 return err;
369
370         active = active_instance(ref, tl);
371         if (!active) {
372                 err = -ENOMEM;
373                 goto out;
374         }
375
376         if (is_barrier(active)) { /* proto-node used by our idle barrier */
377                 /*
378                  * This request is on the kernel_context timeline, and so
379                  * we can use it to substitute for the pending idle-barrer
380                  * request that we want to emit on the kernel_context.
381                  */
382                 __active_del_barrier(ref, node_from_active(active));
383                 RCU_INIT_POINTER(active->fence, NULL);
384                 atomic_dec(&ref->count);
385         }
386         if (!__i915_active_fence_set(active, fence))
387                 atomic_inc(&ref->count);
388
389 out:
390         i915_active_release(ref);
391         return err;
392 }
393
394 struct dma_fence *
395 i915_active_set_exclusive(struct i915_active *ref, struct dma_fence *f)
396 {
397         struct dma_fence *prev;
398
399         /* We expect the caller to manage the exclusive timeline ordering */
400         GEM_BUG_ON(i915_active_is_idle(ref));
401
402         rcu_read_lock();
403         prev = __i915_active_fence_set(&ref->excl, f);
404         if (prev)
405                 prev = dma_fence_get_rcu(prev);
406         else
407                 atomic_inc(&ref->count);
408         rcu_read_unlock();
409
410         return prev;
411 }
412
413 bool i915_active_acquire_if_busy(struct i915_active *ref)
414 {
415         debug_active_assert(ref);
416         return atomic_add_unless(&ref->count, 1, 0);
417 }
418
419 int i915_active_acquire(struct i915_active *ref)
420 {
421         int err;
422
423         if (i915_active_acquire_if_busy(ref))
424                 return 0;
425
426         err = mutex_lock_interruptible(&ref->mutex);
427         if (err)
428                 return err;
429
430         if (likely(!i915_active_acquire_if_busy(ref))) {
431                 if (ref->active)
432                         err = ref->active(ref);
433                 if (!err) {
434                         spin_lock_irq(&ref->tree_lock); /* __active_retire() */
435                         debug_active_activate(ref);
436                         atomic_inc(&ref->count);
437                         spin_unlock_irq(&ref->tree_lock);
438                 }
439         }
440
441         mutex_unlock(&ref->mutex);
442
443         return err;
444 }
445
446 void i915_active_release(struct i915_active *ref)
447 {
448         debug_active_assert(ref);
449         active_retire(ref);
450 }
451
452 static void enable_signaling(struct i915_active_fence *active)
453 {
454         struct dma_fence *fence;
455
456         if (unlikely(is_barrier(active)))
457                 return;
458
459         fence = i915_active_fence_get(active);
460         if (!fence)
461                 return;
462
463         dma_fence_enable_sw_signaling(fence);
464         dma_fence_put(fence);
465 }
466
467 static int flush_barrier(struct active_node *it)
468 {
469         struct intel_engine_cs *engine;
470
471         if (likely(!is_barrier(&it->base)))
472                 return 0;
473
474         engine = __barrier_to_engine(it);
475         smp_rmb(); /* serialise with add_active_barriers */
476         if (!is_barrier(&it->base))
477                 return 0;
478
479         return intel_engine_flush_barriers(engine);
480 }
481
482 static int flush_lazy_signals(struct i915_active *ref)
483 {
484         struct active_node *it, *n;
485         int err = 0;
486
487         enable_signaling(&ref->excl);
488         rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
489                 err = flush_barrier(it); /* unconnected idle barrier? */
490                 if (err)
491                         break;
492
493                 enable_signaling(&it->base);
494         }
495
496         return err;
497 }
498
499 int i915_active_wait(struct i915_active *ref)
500 {
501         int err;
502
503         might_sleep();
504
505         if (!i915_active_acquire_if_busy(ref))
506                 return 0;
507
508         /* Any fence added after the wait begins will not be auto-signaled */
509         err = flush_lazy_signals(ref);
510         i915_active_release(ref);
511         if (err)
512                 return err;
513
514         if (wait_var_event_interruptible(ref, i915_active_is_idle(ref)))
515                 return -EINTR;
516
517         flush_work(&ref->work);
518         return 0;
519 }
520
521 static int __await_active(struct i915_active_fence *active,
522                           int (*fn)(void *arg, struct dma_fence *fence),
523                           void *arg)
524 {
525         struct dma_fence *fence;
526
527         if (is_barrier(active)) /* XXX flush the barrier? */
528                 return 0;
529
530         fence = i915_active_fence_get(active);
531         if (fence) {
532                 int err;
533
534                 err = fn(arg, fence);
535                 dma_fence_put(fence);
536                 if (err < 0)
537                         return err;
538         }
539
540         return 0;
541 }
542
543 static int await_active(struct i915_active *ref,
544                         unsigned int flags,
545                         int (*fn)(void *arg, struct dma_fence *fence),
546                         void *arg)
547 {
548         int err = 0;
549
550         /* We must always wait for the exclusive fence! */
551         if (rcu_access_pointer(ref->excl.fence)) {
552                 err = __await_active(&ref->excl, fn, arg);
553                 if (err)
554                         return err;
555         }
556
557         if (flags & I915_ACTIVE_AWAIT_ALL && i915_active_acquire_if_busy(ref)) {
558                 struct active_node *it, *n;
559
560                 rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
561                         err = __await_active(&it->base, fn, arg);
562                         if (err)
563                                 break;
564                 }
565                 i915_active_release(ref);
566                 if (err)
567                         return err;
568         }
569
570         return 0;
571 }
572
573 static int rq_await_fence(void *arg, struct dma_fence *fence)
574 {
575         return i915_request_await_dma_fence(arg, fence);
576 }
577
578 int i915_request_await_active(struct i915_request *rq,
579                               struct i915_active *ref,
580                               unsigned int flags)
581 {
582         return await_active(ref, flags, rq_await_fence, rq);
583 }
584
585 static int sw_await_fence(void *arg, struct dma_fence *fence)
586 {
587         return i915_sw_fence_await_dma_fence(arg, fence, 0,
588                                              GFP_NOWAIT | __GFP_NOWARN);
589 }
590
591 int i915_sw_fence_await_active(struct i915_sw_fence *fence,
592                                struct i915_active *ref,
593                                unsigned int flags)
594 {
595         return await_active(ref, flags, sw_await_fence, fence);
596 }
597
598 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
599 void i915_active_fini(struct i915_active *ref)
600 {
601         debug_active_fini(ref);
602         GEM_BUG_ON(atomic_read(&ref->count));
603         GEM_BUG_ON(work_pending(&ref->work));
604         GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));
605         mutex_destroy(&ref->mutex);
606 }
607 #endif
608
609 static inline bool is_idle_barrier(struct active_node *node, u64 idx)
610 {
611         return node->timeline == idx && !i915_active_fence_isset(&node->base);
612 }
613
614 static struct active_node *reuse_idle_barrier(struct i915_active *ref, u64 idx)
615 {
616         struct rb_node *prev, *p;
617
618         if (RB_EMPTY_ROOT(&ref->tree))
619                 return NULL;
620
621         spin_lock_irq(&ref->tree_lock);
622         GEM_BUG_ON(i915_active_is_idle(ref));
623
624         /*
625          * Try to reuse any existing barrier nodes already allocated for this
626          * i915_active, due to overlapping active phases there is likely a
627          * node kept alive (as we reuse before parking). We prefer to reuse
628          * completely idle barriers (less hassle in manipulating the llists),
629          * but otherwise any will do.
630          */
631         if (ref->cache && is_idle_barrier(ref->cache, idx)) {
632                 p = &ref->cache->node;
633                 goto match;
634         }
635
636         prev = NULL;
637         p = ref->tree.rb_node;
638         while (p) {
639                 struct active_node *node =
640                         rb_entry(p, struct active_node, node);
641
642                 if (is_idle_barrier(node, idx))
643                         goto match;
644
645                 prev = p;
646                 if (node->timeline < idx)
647                         p = p->rb_right;
648                 else
649                         p = p->rb_left;
650         }
651
652         /*
653          * No quick match, but we did find the leftmost rb_node for the
654          * kernel_context. Walk the rb_tree in-order to see if there were
655          * any idle-barriers on this timeline that we missed, or just use
656          * the first pending barrier.
657          */
658         for (p = prev; p; p = rb_next(p)) {
659                 struct active_node *node =
660                         rb_entry(p, struct active_node, node);
661                 struct intel_engine_cs *engine;
662
663                 if (node->timeline > idx)
664                         break;
665
666                 if (node->timeline < idx)
667                         continue;
668
669                 if (is_idle_barrier(node, idx))
670                         goto match;
671
672                 /*
673                  * The list of pending barriers is protected by the
674                  * kernel_context timeline, which notably we do not hold
675                  * here. i915_request_add_active_barriers() may consume
676                  * the barrier before we claim it, so we have to check
677                  * for success.
678                  */
679                 engine = __barrier_to_engine(node);
680                 smp_rmb(); /* serialise with add_active_barriers */
681                 if (is_barrier(&node->base) &&
682                     ____active_del_barrier(ref, node, engine))
683                         goto match;
684         }
685
686         spin_unlock_irq(&ref->tree_lock);
687
688         return NULL;
689
690 match:
691         rb_erase(p, &ref->tree); /* Hide from waits and sibling allocations */
692         if (p == &ref->cache->node)
693                 ref->cache = NULL;
694         spin_unlock_irq(&ref->tree_lock);
695
696         return rb_entry(p, struct active_node, node);
697 }
698
699 int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
700                                             struct intel_engine_cs *engine)
701 {
702         intel_engine_mask_t tmp, mask = engine->mask;
703         struct llist_node *first = NULL, *last = NULL;
704         struct intel_gt *gt = engine->gt;
705         int err;
706
707         GEM_BUG_ON(i915_active_is_idle(ref));
708
709         /* Wait until the previous preallocation is completed */
710         while (!llist_empty(&ref->preallocated_barriers))
711                 cond_resched();
712
713         /*
714          * Preallocate a node for each physical engine supporting the target
715          * engine (remember virtual engines have more than one sibling).
716          * We can then use the preallocated nodes in
717          * i915_active_acquire_barrier()
718          */
719         GEM_BUG_ON(!mask);
720         for_each_engine_masked(engine, gt, mask, tmp) {
721                 u64 idx = engine->kernel_context->timeline->fence_context;
722                 struct llist_node *prev = first;
723                 struct active_node *node;
724
725                 node = reuse_idle_barrier(ref, idx);
726                 if (!node) {
727                         node = kmem_cache_alloc(global.slab_cache, GFP_KERNEL);
728                         if (!node) {
729                                 err = ENOMEM;
730                                 goto unwind;
731                         }
732
733                         RCU_INIT_POINTER(node->base.fence, NULL);
734                         node->base.cb.func = node_retire;
735                         node->timeline = idx;
736                         node->ref = ref;
737                 }
738
739                 if (!i915_active_fence_isset(&node->base)) {
740                         /*
741                          * Mark this as being *our* unconnected proto-node.
742                          *
743                          * Since this node is not in any list, and we have
744                          * decoupled it from the rbtree, we can reuse the
745                          * request to indicate this is an idle-barrier node
746                          * and then we can use the rb_node and list pointers
747                          * for our tracking of the pending barrier.
748                          */
749                         RCU_INIT_POINTER(node->base.fence, ERR_PTR(-EAGAIN));
750                         node->base.cb.node.prev = (void *)engine;
751                         atomic_inc(&ref->count);
752                 }
753                 GEM_BUG_ON(rcu_access_pointer(node->base.fence) != ERR_PTR(-EAGAIN));
754
755                 GEM_BUG_ON(barrier_to_engine(node) != engine);
756                 first = barrier_to_ll(node);
757                 first->next = prev;
758                 if (!last)
759                         last = first;
760                 intel_engine_pm_get(engine);
761         }
762
763         GEM_BUG_ON(!llist_empty(&ref->preallocated_barriers));
764         llist_add_batch(first, last, &ref->preallocated_barriers);
765
766         return 0;
767
768 unwind:
769         while (first) {
770                 struct active_node *node = barrier_from_ll(first);
771
772                 first = first->next;
773
774                 atomic_dec(&ref->count);
775                 intel_engine_pm_put(barrier_to_engine(node));
776
777                 kmem_cache_free(global.slab_cache, node);
778         }
779         return err;
780 }
781
782 void i915_active_acquire_barrier(struct i915_active *ref)
783 {
784         struct llist_node *pos, *next;
785         unsigned long flags;
786
787         GEM_BUG_ON(i915_active_is_idle(ref));
788
789         /*
790          * Transfer the list of preallocated barriers into the
791          * i915_active rbtree, but only as proto-nodes. They will be
792          * populated by i915_request_add_active_barriers() to point to the
793          * request that will eventually release them.
794          */
795         llist_for_each_safe(pos, next, take_preallocated_barriers(ref)) {
796                 struct active_node *node = barrier_from_ll(pos);
797                 struct intel_engine_cs *engine = barrier_to_engine(node);
798                 struct rb_node **p, *parent;
799
800                 spin_lock_irqsave_nested(&ref->tree_lock, flags,
801                                          SINGLE_DEPTH_NESTING);
802                 parent = NULL;
803                 p = &ref->tree.rb_node;
804                 while (*p) {
805                         struct active_node *it;
806
807                         parent = *p;
808
809                         it = rb_entry(parent, struct active_node, node);
810                         if (it->timeline < node->timeline)
811                                 p = &parent->rb_right;
812                         else
813                                 p = &parent->rb_left;
814                 }
815                 rb_link_node(&node->node, parent, p);
816                 rb_insert_color(&node->node, &ref->tree);
817                 spin_unlock_irqrestore(&ref->tree_lock, flags);
818
819                 GEM_BUG_ON(!intel_engine_pm_is_awake(engine));
820                 llist_add(barrier_to_ll(node), &engine->barrier_tasks);
821                 intel_engine_pm_put(engine);
822         }
823 }
824
825 static struct dma_fence **ll_to_fence_slot(struct llist_node *node)
826 {
827         return __active_fence_slot(&barrier_from_ll(node)->base);
828 }
829
830 void i915_request_add_active_barriers(struct i915_request *rq)
831 {
832         struct intel_engine_cs *engine = rq->engine;
833         struct llist_node *node, *next;
834         unsigned long flags;
835
836         GEM_BUG_ON(!intel_context_is_barrier(rq->context));
837         GEM_BUG_ON(intel_engine_is_virtual(engine));
838         GEM_BUG_ON(i915_request_timeline(rq) != engine->kernel_context->timeline);
839
840         node = llist_del_all(&engine->barrier_tasks);
841         if (!node)
842                 return;
843         /*
844          * Attach the list of proto-fences to the in-flight request such
845          * that the parent i915_active will be released when this request
846          * is retired.
847          */
848         spin_lock_irqsave(&rq->lock, flags);
849         llist_for_each_safe(node, next, node) {
850                 /* serialise with reuse_idle_barrier */
851                 smp_store_mb(*ll_to_fence_slot(node), &rq->fence);
852                 list_add_tail((struct list_head *)node, &rq->fence.cb_list);
853         }
854         spin_unlock_irqrestore(&rq->lock, flags);
855 }
856
857 /*
858  * __i915_active_fence_set: Update the last active fence along its timeline
859  * @active: the active tracker
860  * @fence: the new fence (under construction)
861  *
862  * Records the new @fence as the last active fence along its timeline in
863  * this active tracker, moving the tracking callbacks from the previous
864  * fence onto this one. Returns the previous fence (if not already completed),
865  * which the caller must ensure is executed before the new fence. To ensure
866  * that the order of fences within the timeline of the i915_active_fence is
867  * understood, it should be locked by the caller.
868  */
869 struct dma_fence *
870 __i915_active_fence_set(struct i915_active_fence *active,
871                         struct dma_fence *fence)
872 {
873         struct dma_fence *prev;
874         unsigned long flags;
875
876         if (fence == rcu_access_pointer(active->fence))
877                 return fence;
878
879         GEM_BUG_ON(test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags));
880
881         /*
882          * Consider that we have two threads arriving (A and B), with
883          * C already resident as the active->fence.
884          *
885          * A does the xchg first, and so it sees C or NULL depending
886          * on the timing of the interrupt handler. If it is NULL, the
887          * previous fence must have been signaled and we know that
888          * we are first on the timeline. If it is still present,
889          * we acquire the lock on that fence and serialise with the interrupt
890          * handler, in the process removing it from any future interrupt
891          * callback. A will then wait on C before executing (if present).
892          *
893          * As B is second, it sees A as the previous fence and so waits for
894          * it to complete its transition and takes over the occupancy for
895          * itself -- remembering that it needs to wait on A before executing.
896          *
897          * Note the strong ordering of the timeline also provides consistent
898          * nesting rules for the fence->lock; the inner lock is always the
899          * older lock.
900          */
901         spin_lock_irqsave(fence->lock, flags);
902         prev = xchg(__active_fence_slot(active), fence);
903         if (prev) {
904                 GEM_BUG_ON(prev == fence);
905                 spin_lock_nested(prev->lock, SINGLE_DEPTH_NESTING);
906                 __list_del_entry(&active->cb.node);
907                 spin_unlock(prev->lock); /* serialise with prev->cb_list */
908         }
909         list_add_tail(&active->cb.node, &fence->cb_list);
910         spin_unlock_irqrestore(fence->lock, flags);
911
912         return prev;
913 }
914
915 int i915_active_fence_set(struct i915_active_fence *active,
916                           struct i915_request *rq)
917 {
918         struct dma_fence *fence;
919         int err = 0;
920
921         /* Must maintain timeline ordering wrt previous active requests */
922         rcu_read_lock();
923         fence = __i915_active_fence_set(active, &rq->fence);
924         if (fence) /* but the previous fence may not belong to that timeline! */
925                 fence = dma_fence_get_rcu(fence);
926         rcu_read_unlock();
927         if (fence) {
928                 err = i915_request_await_dma_fence(rq, fence);
929                 dma_fence_put(fence);
930         }
931
932         return err;
933 }
934
935 void i915_active_noop(struct dma_fence *fence, struct dma_fence_cb *cb)
936 {
937         active_fence_cb(fence, cb);
938 }
939
940 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
941 #include "selftests/i915_active.c"
942 #endif
943
944 static void i915_global_active_shrink(void)
945 {
946         kmem_cache_shrink(global.slab_cache);
947 }
948
949 static void i915_global_active_exit(void)
950 {
951         kmem_cache_destroy(global.slab_cache);
952 }
953
954 static struct i915_global_active global = { {
955         .shrink = i915_global_active_shrink,
956         .exit = i915_global_active_exit,
957 } };
958
959 int __init i915_global_active_init(void)
960 {
961         global.slab_cache = KMEM_CACHE(active_node, SLAB_HWCACHE_ALIGN);
962         if (!global.slab_cache)
963                 return -ENOMEM;
964
965         i915_global_register(&global.base);
966         return 0;
967 }