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1/*
2 * Copyright (C) 2012-2014 Canonical Ltd (Maarten Lankhorst)
3 *
4 * Based on bo.c which bears the following copyright notice,
5 * but is dual licensed:
6 *
7 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
8 * All Rights Reserved.
9 *
10 * Permission is hereby granted, free of charge, to any person obtaining a
11 * copy of this software and associated documentation files (the
12 * "Software"), to deal in the Software without restriction, including
13 * without limitation the rights to use, copy, modify, merge, publish,
14 * distribute, sub license, and/or sell copies of the Software, and to
15 * permit persons to whom the Software is furnished to do so, subject to
16 * the following conditions:
17 *
18 * The above copyright notice and this permission notice (including the
19 * next paragraph) shall be included in all copies or substantial portions
20 * of the Software.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
25 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
26 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
27 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
28 * USE OR OTHER DEALINGS IN THE SOFTWARE.
29 *
30 **************************************************************************/
31/*
32 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
33 */
34
35#include <linux/dma-resv.h>
36#include <linux/export.h>
37#include <linux/mm.h>
38#include <linux/sched/mm.h>
39#include <linux/mmu_notifier.h>
40
41/**
42 * DOC: Reservation Object Overview
43 *
44 * The reservation object provides a mechanism to manage shared and
45 * exclusive fences associated with a buffer. A reservation object
46 * can have attached one exclusive fence (normally associated with
47 * write operations) or N shared fences (read operations). The RCU
48 * mechanism is used to protect read access to fences from locked
49 * write-side updates.
50 */
51
52DEFINE_WD_CLASS(reservation_ww_class);
53EXPORT_SYMBOL(reservation_ww_class);
54
55/**
56 * dma_resv_list_alloc - allocate fence list
57 * @shared_max: number of fences we need space for
58 *
59 * Allocate a new dma_resv_list and make sure to correctly initialize
60 * shared_max.
61 */
62static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
63{
64 struct dma_resv_list *list;
65
66 list = kmalloc(offsetof(typeof(*list), shared[shared_max]), GFP_KERNEL);
67 if (!list)
68 return NULL;
69
70 list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
71 sizeof(*list->shared);
72
73 return list;
74}
75
76/**
77 * dma_resv_list_free - free fence list
78 * @list: list to free
79 *
80 * Free a dma_resv_list and make sure to drop all references.
81 */
82static void dma_resv_list_free(struct dma_resv_list *list)
83{
84 unsigned int i;
85
86 if (!list)
87 return;
88
89 for (i = 0; i < list->shared_count; ++i)
90 dma_fence_put(rcu_dereference_protected(list->shared[i], true));
91
92 kfree_rcu(list, rcu);
93}
94
95#if IS_ENABLED(CONFIG_LOCKDEP)
96static int __init dma_resv_lockdep(void)
97{
98 struct mm_struct *mm = mm_alloc();
99 struct ww_acquire_ctx ctx;
100 struct dma_resv obj;
101 int ret;
102
103 if (!mm)
104 return -ENOMEM;
105
106 dma_resv_init(&obj);
107
108 mmap_read_lock(mm);
109 ww_acquire_init(&ctx, &reservation_ww_class);
110 ret = dma_resv_lock(&obj, &ctx);
111 if (ret == -EDEADLK)
112 dma_resv_lock_slow(&obj, &ctx);
113 fs_reclaim_acquire(GFP_KERNEL);
114#ifdef CONFIG_MMU_NOTIFIER
115 lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
116 __dma_fence_might_wait();
117 lock_map_release(&__mmu_notifier_invalidate_range_start_map);
118#else
119 __dma_fence_might_wait();
120#endif
121 fs_reclaim_release(GFP_KERNEL);
122 ww_mutex_unlock(&obj.lock);
123 ww_acquire_fini(&ctx);
124 mmap_read_unlock(mm);
125
126 mmput(mm);
127
128 return 0;
129}
130subsys_initcall(dma_resv_lockdep);
131#endif
132
133/**
134 * dma_resv_init - initialize a reservation object
135 * @obj: the reservation object
136 */
137void dma_resv_init(struct dma_resv *obj)
138{
139 ww_mutex_init(&obj->lock, &reservation_ww_class);
140 seqcount_ww_mutex_init(&obj->seq, &obj->lock);
141
142 RCU_INIT_POINTER(obj->fence, NULL);
143 RCU_INIT_POINTER(obj->fence_excl, NULL);
144}
145EXPORT_SYMBOL(dma_resv_init);
146
147/**
148 * dma_resv_fini - destroys a reservation object
149 * @obj: the reservation object
150 */
151void dma_resv_fini(struct dma_resv *obj)
152{
153 struct dma_resv_list *fobj;
154 struct dma_fence *excl;
155
156 /*
157 * This object should be dead and all references must have
158 * been released to it, so no need to be protected with rcu.
159 */
160 excl = rcu_dereference_protected(obj->fence_excl, 1);
161 if (excl)
162 dma_fence_put(excl);
163
164 fobj = rcu_dereference_protected(obj->fence, 1);
165 dma_resv_list_free(fobj);
166 ww_mutex_destroy(&obj->lock);
167}
168EXPORT_SYMBOL(dma_resv_fini);
169
170/**
171 * dma_resv_reserve_shared - Reserve space to add shared fences to
172 * a dma_resv.
173 * @obj: reservation object
174 * @num_fences: number of fences we want to add
175 *
176 * Should be called before dma_resv_add_shared_fence(). Must
177 * be called with obj->lock held.
178 *
179 * RETURNS
180 * Zero for success, or -errno
181 */
182int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
183{
184 struct dma_resv_list *old, *new;
185 unsigned int i, j, k, max;
186
187 dma_resv_assert_held(obj);
188
189 old = dma_resv_get_list(obj);
190
191 if (old && old->shared_max) {
192 if ((old->shared_count + num_fences) <= old->shared_max)
193 return 0;
194 else
195 max = max(old->shared_count + num_fences,
196 old->shared_max * 2);
197 } else {
198 max = 4;
199 }
200
201 new = dma_resv_list_alloc(max);
202 if (!new)
203 return -ENOMEM;
204
205 /*
206 * no need to bump fence refcounts, rcu_read access
207 * requires the use of kref_get_unless_zero, and the
208 * references from the old struct are carried over to
209 * the new.
210 */
211 for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
212 struct dma_fence *fence;
213
214 fence = rcu_dereference_protected(old->shared[i],
215 dma_resv_held(obj));
216 if (dma_fence_is_signaled(fence))
217 RCU_INIT_POINTER(new->shared[--k], fence);
218 else
219 RCU_INIT_POINTER(new->shared[j++], fence);
220 }
221 new->shared_count = j;
222
223 /*
224 * We are not changing the effective set of fences here so can
225 * merely update the pointer to the new array; both existing
226 * readers and new readers will see exactly the same set of
227 * active (unsignaled) shared fences. Individual fences and the
228 * old array are protected by RCU and so will not vanish under
229 * the gaze of the rcu_read_lock() readers.
230 */
231 rcu_assign_pointer(obj->fence, new);
232
233 if (!old)
234 return 0;
235
236 /* Drop the references to the signaled fences */
237 for (i = k; i < max; ++i) {
238 struct dma_fence *fence;
239
240 fence = rcu_dereference_protected(new->shared[i],
241 dma_resv_held(obj));
242 dma_fence_put(fence);
243 }
244 kfree_rcu(old, rcu);
245
246 return 0;
247}
248EXPORT_SYMBOL(dma_resv_reserve_shared);
249
250/**
251 * dma_resv_add_shared_fence - Add a fence to a shared slot
252 * @obj: the reservation object
253 * @fence: the shared fence to add
254 *
255 * Add a fence to a shared slot, obj->lock must be held, and
256 * dma_resv_reserve_shared() has been called.
257 */
258void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
259{
260 struct dma_resv_list *fobj;
261 struct dma_fence *old;
262 unsigned int i, count;
263
264 dma_fence_get(fence);
265
266 dma_resv_assert_held(obj);
267
268 fobj = dma_resv_get_list(obj);
269 count = fobj->shared_count;
270
271 write_seqcount_begin(&obj->seq);
272
273 for (i = 0; i < count; ++i) {
274
275 old = rcu_dereference_protected(fobj->shared[i],
276 dma_resv_held(obj));
277 if (old->context == fence->context ||
278 dma_fence_is_signaled(old))
279 goto replace;
280 }
281
282 BUG_ON(fobj->shared_count >= fobj->shared_max);
283 old = NULL;
284 count++;
285
286replace:
287 RCU_INIT_POINTER(fobj->shared[i], fence);
288 /* pointer update must be visible before we extend the shared_count */
289 smp_store_mb(fobj->shared_count, count);
290
291 write_seqcount_end(&obj->seq);
292 dma_fence_put(old);
293}
294EXPORT_SYMBOL(dma_resv_add_shared_fence);
295
296/**
297 * dma_resv_add_excl_fence - Add an exclusive fence.
298 * @obj: the reservation object
299 * @fence: the shared fence to add
300 *
301 * Add a fence to the exclusive slot. The obj->lock must be held.
302 */
303void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
304{
305 struct dma_fence *old_fence = dma_resv_get_excl(obj);
306 struct dma_resv_list *old;
307 u32 i = 0;
308
309 dma_resv_assert_held(obj);
310
311 old = dma_resv_get_list(obj);
312 if (old)
313 i = old->shared_count;
314
315 if (fence)
316 dma_fence_get(fence);
317
318 write_seqcount_begin(&obj->seq);
319 /* write_seqcount_begin provides the necessary memory barrier */
320 RCU_INIT_POINTER(obj->fence_excl, fence);
321 if (old)
322 old->shared_count = 0;
323 write_seqcount_end(&obj->seq);
324
325 /* inplace update, no shared fences */
326 while (i--)
327 dma_fence_put(rcu_dereference_protected(old->shared[i],
328 dma_resv_held(obj)));
329
330 dma_fence_put(old_fence);
331}
332EXPORT_SYMBOL(dma_resv_add_excl_fence);
333
334/**
335* dma_resv_copy_fences - Copy all fences from src to dst.
336* @dst: the destination reservation object
337* @src: the source reservation object
338*
339* Copy all fences from src to dst. dst-lock must be held.
340*/
341int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
342{
343 struct dma_resv_list *src_list, *dst_list;
344 struct dma_fence *old, *new;
345 unsigned i;
346
347 dma_resv_assert_held(dst);
348
349 rcu_read_lock();
350 src_list = rcu_dereference(src->fence);
351
352retry:
353 if (src_list) {
354 unsigned shared_count = src_list->shared_count;
355
356 rcu_read_unlock();
357
358 dst_list = dma_resv_list_alloc(shared_count);
359 if (!dst_list)
360 return -ENOMEM;
361
362 rcu_read_lock();
363 src_list = rcu_dereference(src->fence);
364 if (!src_list || src_list->shared_count > shared_count) {
365 kfree(dst_list);
366 goto retry;
367 }
368
369 dst_list->shared_count = 0;
370 for (i = 0; i < src_list->shared_count; ++i) {
371 struct dma_fence *fence;
372
373 fence = rcu_dereference(src_list->shared[i]);
374 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
375 &fence->flags))
376 continue;
377
378 if (!dma_fence_get_rcu(fence)) {
379 dma_resv_list_free(dst_list);
380 src_list = rcu_dereference(src->fence);
381 goto retry;
382 }
383
384 if (dma_fence_is_signaled(fence)) {
385 dma_fence_put(fence);
386 continue;
387 }
388
389 rcu_assign_pointer(dst_list->shared[dst_list->shared_count++], fence);
390 }
391 } else {
392 dst_list = NULL;
393 }
394
395 new = dma_fence_get_rcu_safe(&src->fence_excl);
396 rcu_read_unlock();
397
398 src_list = dma_resv_get_list(dst);
399 old = dma_resv_get_excl(dst);
400
401 write_seqcount_begin(&dst->seq);
402 /* write_seqcount_begin provides the necessary memory barrier */
403 RCU_INIT_POINTER(dst->fence_excl, new);
404 RCU_INIT_POINTER(dst->fence, dst_list);
405 write_seqcount_end(&dst->seq);
406
407 dma_resv_list_free(src_list);
408 dma_fence_put(old);
409
410 return 0;
411}
412EXPORT_SYMBOL(dma_resv_copy_fences);
413
414/**
415 * dma_resv_get_fences_rcu - Get an object's shared and exclusive
416 * fences without update side lock held
417 * @obj: the reservation object
418 * @pfence_excl: the returned exclusive fence (or NULL)
419 * @pshared_count: the number of shared fences returned
420 * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
421 * the required size, and must be freed by caller)
422 *
423 * Retrieve all fences from the reservation object. If the pointer for the
424 * exclusive fence is not specified the fence is put into the array of the
425 * shared fences as well. Returns either zero or -ENOMEM.
426 */
427int dma_resv_get_fences_rcu(struct dma_resv *obj,
428 struct dma_fence **pfence_excl,
429 unsigned *pshared_count,
430 struct dma_fence ***pshared)
431{
432 struct dma_fence **shared = NULL;
433 struct dma_fence *fence_excl;
434 unsigned int shared_count;
435 int ret = 1;
436
437 do {
438 struct dma_resv_list *fobj;
439 unsigned int i, seq;
440 size_t sz = 0;
441
442 shared_count = i = 0;
443
444 rcu_read_lock();
445 seq = read_seqcount_begin(&obj->seq);
446
447 fence_excl = rcu_dereference(obj->fence_excl);
448 if (fence_excl && !dma_fence_get_rcu(fence_excl))
449 goto unlock;
450
451 fobj = rcu_dereference(obj->fence);
452 if (fobj)
453 sz += sizeof(*shared) * fobj->shared_max;
454
455 if (!pfence_excl && fence_excl)
456 sz += sizeof(*shared);
457
458 if (sz) {
459 struct dma_fence **nshared;
460
461 nshared = krealloc(shared, sz,
462 GFP_NOWAIT | __GFP_NOWARN);
463 if (!nshared) {
464 rcu_read_unlock();
465
466 dma_fence_put(fence_excl);
467 fence_excl = NULL;
468
469 nshared = krealloc(shared, sz, GFP_KERNEL);
470 if (nshared) {
471 shared = nshared;
472 continue;
473 }
474
475 ret = -ENOMEM;
476 break;
477 }
478 shared = nshared;
479 shared_count = fobj ? fobj->shared_count : 0;
480 for (i = 0; i < shared_count; ++i) {
481 shared[i] = rcu_dereference(fobj->shared[i]);
482 if (!dma_fence_get_rcu(shared[i]))
483 break;
484 }
485 }
486
487 if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
488 while (i--)
489 dma_fence_put(shared[i]);
490 dma_fence_put(fence_excl);
491 goto unlock;
492 }
493
494 ret = 0;
495unlock:
496 rcu_read_unlock();
497 } while (ret);
498
499 if (pfence_excl)
500 *pfence_excl = fence_excl;
501 else if (fence_excl)
502 shared[shared_count++] = fence_excl;
503
504 if (!shared_count) {
505 kfree(shared);
506 shared = NULL;
507 }
508
509 *pshared_count = shared_count;
510 *pshared = shared;
511 return ret;
512}
513EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu);
514
515/**
516 * dma_resv_wait_timeout_rcu - Wait on reservation's objects
517 * shared and/or exclusive fences.
518 * @obj: the reservation object
519 * @wait_all: if true, wait on all fences, else wait on just exclusive fence
520 * @intr: if true, do interruptible wait
521 * @timeout: timeout value in jiffies or zero to return immediately
522 *
523 * RETURNS
524 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
525 * greater than zer on success.
526 */
527long dma_resv_wait_timeout_rcu(struct dma_resv *obj,
528 bool wait_all, bool intr,
529 unsigned long timeout)
530{
531 struct dma_fence *fence;
532 unsigned seq, shared_count;
533 long ret = timeout ? timeout : 1;
534 int i;
535
536retry:
537 shared_count = 0;
538 seq = read_seqcount_begin(&obj->seq);
539 rcu_read_lock();
540 i = -1;
541
542 fence = rcu_dereference(obj->fence_excl);
543 if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
544 if (!dma_fence_get_rcu(fence))
545 goto unlock_retry;
546
547 if (dma_fence_is_signaled(fence)) {
548 dma_fence_put(fence);
549 fence = NULL;
550 }
551
552 } else {
553 fence = NULL;
554 }
555
556 if (wait_all) {
557 struct dma_resv_list *fobj = rcu_dereference(obj->fence);
558
559 if (fobj)
560 shared_count = fobj->shared_count;
561
562 for (i = 0; !fence && i < shared_count; ++i) {
563 struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
564
565 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
566 &lfence->flags))
567 continue;
568
569 if (!dma_fence_get_rcu(lfence))
570 goto unlock_retry;
571
572 if (dma_fence_is_signaled(lfence)) {
573 dma_fence_put(lfence);
574 continue;
575 }
576
577 fence = lfence;
578 break;
579 }
580 }
581
582 rcu_read_unlock();
583 if (fence) {
584 if (read_seqcount_retry(&obj->seq, seq)) {
585 dma_fence_put(fence);
586 goto retry;
587 }
588
589 ret = dma_fence_wait_timeout(fence, intr, ret);
590 dma_fence_put(fence);
591 if (ret > 0 && wait_all && (i + 1 < shared_count))
592 goto retry;
593 }
594 return ret;
595
596unlock_retry:
597 rcu_read_unlock();
598 goto retry;
599}
600EXPORT_SYMBOL_GPL(dma_resv_wait_timeout_rcu);
601
602
603static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
604{
605 struct dma_fence *fence, *lfence = passed_fence;
606 int ret = 1;
607
608 if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
609 fence = dma_fence_get_rcu(lfence);
610 if (!fence)
611 return -1;
612
613 ret = !!dma_fence_is_signaled(fence);
614 dma_fence_put(fence);
615 }
616 return ret;
617}
618
619/**
620 * dma_resv_test_signaled_rcu - Test if a reservation object's
621 * fences have been signaled.
622 * @obj: the reservation object
623 * @test_all: if true, test all fences, otherwise only test the exclusive
624 * fence
625 *
626 * RETURNS
627 * true if all fences signaled, else false
628 */
629bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all)
630{
631 unsigned seq, shared_count;
632 int ret;
633
634 rcu_read_lock();
635retry:
636 ret = true;
637 shared_count = 0;
638 seq = read_seqcount_begin(&obj->seq);
639
640 if (test_all) {
641 unsigned i;
642
643 struct dma_resv_list *fobj = rcu_dereference(obj->fence);
644
645 if (fobj)
646 shared_count = fobj->shared_count;
647
648 for (i = 0; i < shared_count; ++i) {
649 struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
650
651 ret = dma_resv_test_signaled_single(fence);
652 if (ret < 0)
653 goto retry;
654 else if (!ret)
655 break;
656 }
657
658 if (read_seqcount_retry(&obj->seq, seq))
659 goto retry;
660 }
661
662 if (!shared_count) {
663 struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl);
664
665 if (fence_excl) {
666 ret = dma_resv_test_signaled_single(fence_excl);
667 if (ret < 0)
668 goto retry;
669
670 if (read_seqcount_retry(&obj->seq, seq))
671 goto retry;
672 }
673 }
674
675 rcu_read_unlock();
676 return ret;
677}
678EXPORT_SYMBOL_GPL(dma_resv_test_signaled_rcu);