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1// SPDX-License-Identifier: MIT
2/*
3 * Copyright (C) 2012-2014 Canonical Ltd (Maarten Lankhorst)
4 *
5 * Based on bo.c which bears the following copyright notice,
6 * but is dual licensed:
7 *
8 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
9 * All Rights Reserved.
10 *
11 * Permission is hereby granted, free of charge, to any person obtaining a
12 * copy of this software and associated documentation files (the
13 * "Software"), to deal in the Software without restriction, including
14 * without limitation the rights to use, copy, modify, merge, publish,
15 * distribute, sub license, and/or sell copies of the Software, and to
16 * permit persons to whom the Software is furnished to do so, subject to
17 * the following conditions:
18 *
19 * The above copyright notice and this permission notice (including the
20 * next paragraph) shall be included in all copies or substantial portions
21 * of the Software.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
24 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
25 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
26 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
27 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
28 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
29 * USE OR OTHER DEALINGS IN THE SOFTWARE.
30 *
31 **************************************************************************/
32/*
33 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
34 */
35
36#include <linux/dma-resv.h>
37#include <linux/dma-fence-array.h>
38#include <linux/export.h>
39#include <linux/mm.h>
40#include <linux/sched/mm.h>
41#include <linux/mmu_notifier.h>
42#include <linux/seq_file.h>
43
44/**
45 * DOC: Reservation Object Overview
46 *
47 * The reservation object provides a mechanism to manage a container of
48 * dma_fence object associated with a resource. A reservation object
49 * can have any number of fences attaches to it. Each fence carries an usage
50 * parameter determining how the operation represented by the fence is using the
51 * resource. The RCU mechanism is used to protect read access to fences from
52 * locked write-side updates.
53 *
54 * See struct dma_resv for more details.
55 */
56
57DEFINE_WD_CLASS(reservation_ww_class);
58EXPORT_SYMBOL(reservation_ww_class);
59
60/* Mask for the lower fence pointer bits */
61#define DMA_RESV_LIST_MASK 0x3
62
63struct dma_resv_list {
64 struct rcu_head rcu;
65 u32 num_fences, max_fences;
66 struct dma_fence __rcu *table[];
67};
68
69/* Extract the fence and usage flags from an RCU protected entry in the list. */
70static void dma_resv_list_entry(struct dma_resv_list *list, unsigned int index,
71 struct dma_resv *resv, struct dma_fence **fence,
72 enum dma_resv_usage *usage)
73{
74 long tmp;
75
76 tmp = (long)rcu_dereference_check(list->table[index],
77 resv ? dma_resv_held(resv) : true);
78 *fence = (struct dma_fence *)(tmp & ~DMA_RESV_LIST_MASK);
79 if (usage)
80 *usage = tmp & DMA_RESV_LIST_MASK;
81}
82
83/* Set the fence and usage flags at the specific index in the list. */
84static void dma_resv_list_set(struct dma_resv_list *list,
85 unsigned int index,
86 struct dma_fence *fence,
87 enum dma_resv_usage usage)
88{
89 long tmp = ((long)fence) | usage;
90
91 RCU_INIT_POINTER(list->table[index], (struct dma_fence *)tmp);
92}
93
94/*
95 * Allocate a new dma_resv_list and make sure to correctly initialize
96 * max_fences.
97 */
98static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences)
99{
100 struct dma_resv_list *list;
101 size_t size;
102
103 /* Round up to the next kmalloc bucket size. */
104 size = kmalloc_size_roundup(struct_size(list, table, max_fences));
105
106 list = kmalloc(size, GFP_KERNEL);
107 if (!list)
108 return NULL;
109
110 /* Given the resulting bucket size, recalculated max_fences. */
111 list->max_fences = (size - offsetof(typeof(*list), table)) /
112 sizeof(*list->table);
113
114 return list;
115}
116
117/* Free a dma_resv_list and make sure to drop all references. */
118static void dma_resv_list_free(struct dma_resv_list *list)
119{
120 unsigned int i;
121
122 if (!list)
123 return;
124
125 for (i = 0; i < list->num_fences; ++i) {
126 struct dma_fence *fence;
127
128 dma_resv_list_entry(list, i, NULL, &fence, NULL);
129 dma_fence_put(fence);
130 }
131 kfree_rcu(list, rcu);
132}
133
134/**
135 * dma_resv_init - initialize a reservation object
136 * @obj: the reservation object
137 */
138void dma_resv_init(struct dma_resv *obj)
139{
140 ww_mutex_init(&obj->lock, &reservation_ww_class);
141
142 RCU_INIT_POINTER(obj->fences, NULL);
143}
144EXPORT_SYMBOL(dma_resv_init);
145
146/**
147 * dma_resv_fini - destroys a reservation object
148 * @obj: the reservation object
149 */
150void dma_resv_fini(struct dma_resv *obj)
151{
152 /*
153 * This object should be dead and all references must have
154 * been released to it, so no need to be protected with rcu.
155 */
156 dma_resv_list_free(rcu_dereference_protected(obj->fences, true));
157 ww_mutex_destroy(&obj->lock);
158}
159EXPORT_SYMBOL(dma_resv_fini);
160
161/* Dereference the fences while ensuring RCU rules */
162static inline struct dma_resv_list *dma_resv_fences_list(struct dma_resv *obj)
163{
164 return rcu_dereference_check(obj->fences, dma_resv_held(obj));
165}
166
167/**
168 * dma_resv_reserve_fences - Reserve space to add fences to a dma_resv object.
169 * @obj: reservation object
170 * @num_fences: number of fences we want to add
171 *
172 * Should be called before dma_resv_add_fence(). Must be called with @obj
173 * locked through dma_resv_lock().
174 *
175 * Note that the preallocated slots need to be re-reserved if @obj is unlocked
176 * at any time before calling dma_resv_add_fence(). This is validated when
177 * CONFIG_DEBUG_MUTEXES is enabled.
178 *
179 * RETURNS
180 * Zero for success, or -errno
181 */
182int dma_resv_reserve_fences(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_fences_list(obj);
190 if (old && old->max_fences) {
191 if ((old->num_fences + num_fences) <= old->max_fences)
192 return 0;
193 max = max(old->num_fences + num_fences, old->max_fences * 2);
194 } else {
195 max = max(4ul, roundup_pow_of_two(num_fences));
196 }
197
198 new = dma_resv_list_alloc(max);
199 if (!new)
200 return -ENOMEM;
201
202 /*
203 * no need to bump fence refcounts, rcu_read access
204 * requires the use of kref_get_unless_zero, and the
205 * references from the old struct are carried over to
206 * the new.
207 */
208 for (i = 0, j = 0, k = max; i < (old ? old->num_fences : 0); ++i) {
209 enum dma_resv_usage usage;
210 struct dma_fence *fence;
211
212 dma_resv_list_entry(old, i, obj, &fence, &usage);
213 if (dma_fence_is_signaled(fence))
214 RCU_INIT_POINTER(new->table[--k], fence);
215 else
216 dma_resv_list_set(new, j++, fence, usage);
217 }
218 new->num_fences = j;
219
220 /*
221 * We are not changing the effective set of fences here so can
222 * merely update the pointer to the new array; both existing
223 * readers and new readers will see exactly the same set of
224 * active (unsignaled) fences. Individual fences and the
225 * old array are protected by RCU and so will not vanish under
226 * the gaze of the rcu_read_lock() readers.
227 */
228 rcu_assign_pointer(obj->fences, new);
229
230 if (!old)
231 return 0;
232
233 /* Drop the references to the signaled fences */
234 for (i = k; i < max; ++i) {
235 struct dma_fence *fence;
236
237 fence = rcu_dereference_protected(new->table[i],
238 dma_resv_held(obj));
239 dma_fence_put(fence);
240 }
241 kfree_rcu(old, rcu);
242
243 return 0;
244}
245EXPORT_SYMBOL(dma_resv_reserve_fences);
246
247#ifdef CONFIG_DEBUG_MUTEXES
248/**
249 * dma_resv_reset_max_fences - reset fences for debugging
250 * @obj: the dma_resv object to reset
251 *
252 * Reset the number of pre-reserved fence slots to test that drivers do
253 * correct slot allocation using dma_resv_reserve_fences(). See also
254 * &dma_resv_list.max_fences.
255 */
256void dma_resv_reset_max_fences(struct dma_resv *obj)
257{
258 struct dma_resv_list *fences = dma_resv_fences_list(obj);
259
260 dma_resv_assert_held(obj);
261
262 /* Test fence slot reservation */
263 if (fences)
264 fences->max_fences = fences->num_fences;
265}
266EXPORT_SYMBOL(dma_resv_reset_max_fences);
267#endif
268
269/**
270 * dma_resv_add_fence - Add a fence to the dma_resv obj
271 * @obj: the reservation object
272 * @fence: the fence to add
273 * @usage: how the fence is used, see enum dma_resv_usage
274 *
275 * Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
276 * dma_resv_reserve_fences() has been called.
277 *
278 * See also &dma_resv.fence for a discussion of the semantics.
279 */
280void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
281 enum dma_resv_usage usage)
282{
283 struct dma_resv_list *fobj;
284 struct dma_fence *old;
285 unsigned int i, count;
286
287 dma_fence_get(fence);
288
289 dma_resv_assert_held(obj);
290
291 /* Drivers should not add containers here, instead add each fence
292 * individually.
293 */
294 WARN_ON(dma_fence_is_container(fence));
295
296 fobj = dma_resv_fences_list(obj);
297 count = fobj->num_fences;
298
299 for (i = 0; i < count; ++i) {
300 enum dma_resv_usage old_usage;
301
302 dma_resv_list_entry(fobj, i, obj, &old, &old_usage);
303 if ((old->context == fence->context && old_usage >= usage &&
304 dma_fence_is_later_or_same(fence, old)) ||
305 dma_fence_is_signaled(old)) {
306 dma_resv_list_set(fobj, i, fence, usage);
307 dma_fence_put(old);
308 return;
309 }
310 }
311
312 BUG_ON(fobj->num_fences >= fobj->max_fences);
313 count++;
314
315 dma_resv_list_set(fobj, i, fence, usage);
316 /* pointer update must be visible before we extend the num_fences */
317 smp_store_mb(fobj->num_fences, count);
318}
319EXPORT_SYMBOL(dma_resv_add_fence);
320
321/**
322 * dma_resv_replace_fences - replace fences in the dma_resv obj
323 * @obj: the reservation object
324 * @context: the context of the fences to replace
325 * @replacement: the new fence to use instead
326 * @usage: how the new fence is used, see enum dma_resv_usage
327 *
328 * Replace fences with a specified context with a new fence. Only valid if the
329 * operation represented by the original fence has no longer access to the
330 * resources represented by the dma_resv object when the new fence completes.
331 *
332 * And example for using this is replacing a preemption fence with a page table
333 * update fence which makes the resource inaccessible.
334 */
335void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
336 struct dma_fence *replacement,
337 enum dma_resv_usage usage)
338{
339 struct dma_resv_list *list;
340 unsigned int i;
341
342 dma_resv_assert_held(obj);
343
344 list = dma_resv_fences_list(obj);
345 for (i = 0; list && i < list->num_fences; ++i) {
346 struct dma_fence *old;
347
348 dma_resv_list_entry(list, i, obj, &old, NULL);
349 if (old->context != context)
350 continue;
351
352 dma_resv_list_set(list, i, dma_fence_get(replacement), usage);
353 dma_fence_put(old);
354 }
355}
356EXPORT_SYMBOL(dma_resv_replace_fences);
357
358/* Restart the unlocked iteration by initializing the cursor object. */
359static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
360{
361 cursor->index = 0;
362 cursor->num_fences = 0;
363 cursor->fences = dma_resv_fences_list(cursor->obj);
364 if (cursor->fences)
365 cursor->num_fences = cursor->fences->num_fences;
366 cursor->is_restarted = true;
367}
368
369/* Walk to the next not signaled fence and grab a reference to it */
370static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
371{
372 if (!cursor->fences)
373 return;
374
375 do {
376 /* Drop the reference from the previous round */
377 dma_fence_put(cursor->fence);
378
379 if (cursor->index >= cursor->num_fences) {
380 cursor->fence = NULL;
381 break;
382
383 }
384
385 dma_resv_list_entry(cursor->fences, cursor->index++,
386 cursor->obj, &cursor->fence,
387 &cursor->fence_usage);
388 cursor->fence = dma_fence_get_rcu(cursor->fence);
389 if (!cursor->fence) {
390 dma_resv_iter_restart_unlocked(cursor);
391 continue;
392 }
393
394 if (!dma_fence_is_signaled(cursor->fence) &&
395 cursor->usage >= cursor->fence_usage)
396 break;
397 } while (true);
398}
399
400/**
401 * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
402 * @cursor: the cursor with the current position
403 *
404 * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
405 *
406 * Beware that the iterator can be restarted. Code which accumulates statistics
407 * or similar needs to check for this with dma_resv_iter_is_restarted(). For
408 * this reason prefer the locked dma_resv_iter_first() whenver possible.
409 *
410 * Returns the first fence from an unlocked dma_resv obj.
411 */
412struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
413{
414 rcu_read_lock();
415 do {
416 dma_resv_iter_restart_unlocked(cursor);
417 dma_resv_iter_walk_unlocked(cursor);
418 } while (dma_resv_fences_list(cursor->obj) != cursor->fences);
419 rcu_read_unlock();
420
421 return cursor->fence;
422}
423EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
424
425/**
426 * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
427 * @cursor: the cursor with the current position
428 *
429 * Beware that the iterator can be restarted. Code which accumulates statistics
430 * or similar needs to check for this with dma_resv_iter_is_restarted(). For
431 * this reason prefer the locked dma_resv_iter_next() whenver possible.
432 *
433 * Returns the next fence from an unlocked dma_resv obj.
434 */
435struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
436{
437 bool restart;
438
439 rcu_read_lock();
440 cursor->is_restarted = false;
441 restart = dma_resv_fences_list(cursor->obj) != cursor->fences;
442 do {
443 if (restart)
444 dma_resv_iter_restart_unlocked(cursor);
445 dma_resv_iter_walk_unlocked(cursor);
446 restart = true;
447 } while (dma_resv_fences_list(cursor->obj) != cursor->fences);
448 rcu_read_unlock();
449
450 return cursor->fence;
451}
452EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
453
454/**
455 * dma_resv_iter_first - first fence from a locked dma_resv object
456 * @cursor: cursor to record the current position
457 *
458 * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
459 *
460 * Return the first fence in the dma_resv object while holding the
461 * &dma_resv.lock.
462 */
463struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
464{
465 struct dma_fence *fence;
466
467 dma_resv_assert_held(cursor->obj);
468
469 cursor->index = 0;
470 cursor->fences = dma_resv_fences_list(cursor->obj);
471
472 fence = dma_resv_iter_next(cursor);
473 cursor->is_restarted = true;
474 return fence;
475}
476EXPORT_SYMBOL_GPL(dma_resv_iter_first);
477
478/**
479 * dma_resv_iter_next - next fence from a locked dma_resv object
480 * @cursor: cursor to record the current position
481 *
482 * Return the next fences from the dma_resv object while holding the
483 * &dma_resv.lock.
484 */
485struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
486{
487 struct dma_fence *fence;
488
489 dma_resv_assert_held(cursor->obj);
490
491 cursor->is_restarted = false;
492
493 do {
494 if (!cursor->fences ||
495 cursor->index >= cursor->fences->num_fences)
496 return NULL;
497
498 dma_resv_list_entry(cursor->fences, cursor->index++,
499 cursor->obj, &fence, &cursor->fence_usage);
500 } while (cursor->fence_usage > cursor->usage);
501
502 return fence;
503}
504EXPORT_SYMBOL_GPL(dma_resv_iter_next);
505
506/**
507 * dma_resv_copy_fences - Copy all fences from src to dst.
508 * @dst: the destination reservation object
509 * @src: the source reservation object
510 *
511 * Copy all fences from src to dst. dst-lock must be held.
512 */
513int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
514{
515 struct dma_resv_iter cursor;
516 struct dma_resv_list *list;
517 struct dma_fence *f;
518
519 dma_resv_assert_held(dst);
520
521 list = NULL;
522
523 dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP);
524 dma_resv_for_each_fence_unlocked(&cursor, f) {
525
526 if (dma_resv_iter_is_restarted(&cursor)) {
527 dma_resv_list_free(list);
528
529 list = dma_resv_list_alloc(cursor.num_fences);
530 if (!list) {
531 dma_resv_iter_end(&cursor);
532 return -ENOMEM;
533 }
534 list->num_fences = 0;
535 }
536
537 dma_fence_get(f);
538 dma_resv_list_set(list, list->num_fences++, f,
539 dma_resv_iter_usage(&cursor));
540 }
541 dma_resv_iter_end(&cursor);
542
543 list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
544 dma_resv_list_free(list);
545 return 0;
546}
547EXPORT_SYMBOL(dma_resv_copy_fences);
548
549/**
550 * dma_resv_get_fences - Get an object's fences
551 * fences without update side lock held
552 * @obj: the reservation object
553 * @usage: controls which fences to include, see enum dma_resv_usage.
554 * @num_fences: the number of fences returned
555 * @fences: the array of fence ptrs returned (array is krealloc'd to the
556 * required size, and must be freed by caller)
557 *
558 * Retrieve all fences from the reservation object.
559 * Returns either zero or -ENOMEM.
560 */
561int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
562 unsigned int *num_fences, struct dma_fence ***fences)
563{
564 struct dma_resv_iter cursor;
565 struct dma_fence *fence;
566
567 *num_fences = 0;
568 *fences = NULL;
569
570 dma_resv_iter_begin(&cursor, obj, usage);
571 dma_resv_for_each_fence_unlocked(&cursor, fence) {
572
573 if (dma_resv_iter_is_restarted(&cursor)) {
574 struct dma_fence **new_fences;
575 unsigned int count;
576
577 while (*num_fences)
578 dma_fence_put((*fences)[--(*num_fences)]);
579
580 count = cursor.num_fences + 1;
581
582 /* Eventually re-allocate the array */
583 new_fences = krealloc_array(*fences, count,
584 sizeof(void *),
585 GFP_KERNEL);
586 if (count && !new_fences) {
587 kfree(*fences);
588 *fences = NULL;
589 *num_fences = 0;
590 dma_resv_iter_end(&cursor);
591 return -ENOMEM;
592 }
593 *fences = new_fences;
594 }
595
596 (*fences)[(*num_fences)++] = dma_fence_get(fence);
597 }
598 dma_resv_iter_end(&cursor);
599
600 return 0;
601}
602EXPORT_SYMBOL_GPL(dma_resv_get_fences);
603
604/**
605 * dma_resv_get_singleton - Get a single fence for all the fences
606 * @obj: the reservation object
607 * @usage: controls which fences to include, see enum dma_resv_usage.
608 * @fence: the resulting fence
609 *
610 * Get a single fence representing all the fences inside the resv object.
611 * Returns either 0 for success or -ENOMEM.
612 *
613 * Warning: This can't be used like this when adding the fence back to the resv
614 * object since that can lead to stack corruption when finalizing the
615 * dma_fence_array.
616 *
617 * Returns 0 on success and negative error values on failure.
618 */
619int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
620 struct dma_fence **fence)
621{
622 struct dma_fence_array *array;
623 struct dma_fence **fences;
624 unsigned count;
625 int r;
626
627 r = dma_resv_get_fences(obj, usage, &count, &fences);
628 if (r)
629 return r;
630
631 if (count == 0) {
632 *fence = NULL;
633 return 0;
634 }
635
636 if (count == 1) {
637 *fence = fences[0];
638 kfree(fences);
639 return 0;
640 }
641
642 array = dma_fence_array_create(count, fences,
643 dma_fence_context_alloc(1),
644 1, false);
645 if (!array) {
646 while (count--)
647 dma_fence_put(fences[count]);
648 kfree(fences);
649 return -ENOMEM;
650 }
651
652 *fence = &array->base;
653 return 0;
654}
655EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
656
657/**
658 * dma_resv_wait_timeout - Wait on reservation's objects fences
659 * @obj: the reservation object
660 * @usage: controls which fences to include, see enum dma_resv_usage.
661 * @intr: if true, do interruptible wait
662 * @timeout: timeout value in jiffies or zero to return immediately
663 *
664 * Callers are not required to hold specific locks, but maybe hold
665 * dma_resv_lock() already
666 * RETURNS
667 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
668 * greater than zero on success.
669 */
670long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
671 bool intr, unsigned long timeout)
672{
673 long ret = timeout ? timeout : 1;
674 struct dma_resv_iter cursor;
675 struct dma_fence *fence;
676
677 dma_resv_iter_begin(&cursor, obj, usage);
678 dma_resv_for_each_fence_unlocked(&cursor, fence) {
679
680 ret = dma_fence_wait_timeout(fence, intr, ret);
681 if (ret <= 0) {
682 dma_resv_iter_end(&cursor);
683 return ret;
684 }
685 }
686 dma_resv_iter_end(&cursor);
687
688 return ret;
689}
690EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
691
692/**
693 * dma_resv_set_deadline - Set a deadline on reservation's objects fences
694 * @obj: the reservation object
695 * @usage: controls which fences to include, see enum dma_resv_usage.
696 * @deadline: the requested deadline (MONOTONIC)
697 *
698 * May be called without holding the dma_resv lock. Sets @deadline on
699 * all fences filtered by @usage.
700 */
701void dma_resv_set_deadline(struct dma_resv *obj, enum dma_resv_usage usage,
702 ktime_t deadline)
703{
704 struct dma_resv_iter cursor;
705 struct dma_fence *fence;
706
707 dma_resv_iter_begin(&cursor, obj, usage);
708 dma_resv_for_each_fence_unlocked(&cursor, fence) {
709 dma_fence_set_deadline(fence, deadline);
710 }
711 dma_resv_iter_end(&cursor);
712}
713EXPORT_SYMBOL_GPL(dma_resv_set_deadline);
714
715/**
716 * dma_resv_test_signaled - Test if a reservation object's fences have been
717 * signaled.
718 * @obj: the reservation object
719 * @usage: controls which fences to include, see enum dma_resv_usage.
720 *
721 * Callers are not required to hold specific locks, but maybe hold
722 * dma_resv_lock() already.
723 *
724 * RETURNS
725 *
726 * True if all fences signaled, else false.
727 */
728bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage)
729{
730 struct dma_resv_iter cursor;
731 struct dma_fence *fence;
732
733 dma_resv_iter_begin(&cursor, obj, usage);
734 dma_resv_for_each_fence_unlocked(&cursor, fence) {
735 dma_resv_iter_end(&cursor);
736 return false;
737 }
738 dma_resv_iter_end(&cursor);
739 return true;
740}
741EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
742
743/**
744 * dma_resv_describe - Dump description of the resv object into seq_file
745 * @obj: the reservation object
746 * @seq: the seq_file to dump the description into
747 *
748 * Dump a textual description of the fences inside an dma_resv object into the
749 * seq_file.
750 */
751void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
752{
753 static const char *usage[] = { "kernel", "write", "read", "bookkeep" };
754 struct dma_resv_iter cursor;
755 struct dma_fence *fence;
756
757 dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
758 seq_printf(seq, "\t%s fence:",
759 usage[dma_resv_iter_usage(&cursor)]);
760 dma_fence_describe(fence, seq);
761 }
762}
763EXPORT_SYMBOL_GPL(dma_resv_describe);
764
765#if IS_ENABLED(CONFIG_LOCKDEP)
766static int __init dma_resv_lockdep(void)
767{
768 struct mm_struct *mm = mm_alloc();
769 struct ww_acquire_ctx ctx;
770 struct dma_resv obj;
771 struct address_space mapping;
772 int ret;
773
774 if (!mm)
775 return -ENOMEM;
776
777 dma_resv_init(&obj);
778 address_space_init_once(&mapping);
779
780 mmap_read_lock(mm);
781 ww_acquire_init(&ctx, &reservation_ww_class);
782 ret = dma_resv_lock(&obj, &ctx);
783 if (ret == -EDEADLK)
784 dma_resv_lock_slow(&obj, &ctx);
785 fs_reclaim_acquire(GFP_KERNEL);
786 /* for unmap_mapping_range on trylocked buffer objects in shrinkers */
787 i_mmap_lock_write(&mapping);
788 i_mmap_unlock_write(&mapping);
789#ifdef CONFIG_MMU_NOTIFIER
790 lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
791 __dma_fence_might_wait();
792 lock_map_release(&__mmu_notifier_invalidate_range_start_map);
793#else
794 __dma_fence_might_wait();
795#endif
796 fs_reclaim_release(GFP_KERNEL);
797 ww_mutex_unlock(&obj.lock);
798 ww_acquire_fini(&ctx);
799 mmap_read_unlock(mm);
800
801 mmput(mm);
802
803 return 0;
804}
805subsys_initcall(dma_resv_lockdep);
806#endif
1// SPDX-License-Identifier: MIT
2/*
3 * Copyright (C) 2012-2014 Canonical Ltd (Maarten Lankhorst)
4 *
5 * Based on bo.c which bears the following copyright notice,
6 * but is dual licensed:
7 *
8 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
9 * All Rights Reserved.
10 *
11 * Permission is hereby granted, free of charge, to any person obtaining a
12 * copy of this software and associated documentation files (the
13 * "Software"), to deal in the Software without restriction, including
14 * without limitation the rights to use, copy, modify, merge, publish,
15 * distribute, sub license, and/or sell copies of the Software, and to
16 * permit persons to whom the Software is furnished to do so, subject to
17 * the following conditions:
18 *
19 * The above copyright notice and this permission notice (including the
20 * next paragraph) shall be included in all copies or substantial portions
21 * of the Software.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
24 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
25 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
26 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
27 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
28 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
29 * USE OR OTHER DEALINGS IN THE SOFTWARE.
30 *
31 **************************************************************************/
32/*
33 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
34 */
35
36#include <linux/dma-resv.h>
37#include <linux/export.h>
38#include <linux/mm.h>
39#include <linux/sched/mm.h>
40#include <linux/mmu_notifier.h>
41
42/**
43 * DOC: Reservation Object Overview
44 *
45 * The reservation object provides a mechanism to manage shared and
46 * exclusive fences associated with a buffer. A reservation object
47 * can have attached one exclusive fence (normally associated with
48 * write operations) or N shared fences (read operations). The RCU
49 * mechanism is used to protect read access to fences from locked
50 * write-side updates.
51 */
52
53DEFINE_WD_CLASS(reservation_ww_class);
54EXPORT_SYMBOL(reservation_ww_class);
55
56/**
57 * dma_resv_list_alloc - allocate fence list
58 * @shared_max: number of fences we need space for
59 *
60 * Allocate a new dma_resv_list and make sure to correctly initialize
61 * shared_max.
62 */
63static struct dma_resv_list *dma_resv_list_alloc(unsigned int shared_max)
64{
65 struct dma_resv_list *list;
66
67 list = kmalloc(struct_size(list, shared, shared_max), GFP_KERNEL);
68 if (!list)
69 return NULL;
70
71 list->shared_max = (ksize(list) - offsetof(typeof(*list), shared)) /
72 sizeof(*list->shared);
73
74 return list;
75}
76
77/**
78 * dma_resv_list_free - free fence list
79 * @list: list to free
80 *
81 * Free a dma_resv_list and make sure to drop all references.
82 */
83static void dma_resv_list_free(struct dma_resv_list *list)
84{
85 unsigned int i;
86
87 if (!list)
88 return;
89
90 for (i = 0; i < list->shared_count; ++i)
91 dma_fence_put(rcu_dereference_protected(list->shared[i], true));
92
93 kfree_rcu(list, rcu);
94}
95
96/**
97 * dma_resv_init - initialize a reservation object
98 * @obj: the reservation object
99 */
100void dma_resv_init(struct dma_resv *obj)
101{
102 ww_mutex_init(&obj->lock, &reservation_ww_class);
103 seqcount_ww_mutex_init(&obj->seq, &obj->lock);
104
105 RCU_INIT_POINTER(obj->fence, NULL);
106 RCU_INIT_POINTER(obj->fence_excl, NULL);
107}
108EXPORT_SYMBOL(dma_resv_init);
109
110/**
111 * dma_resv_fini - destroys a reservation object
112 * @obj: the reservation object
113 */
114void dma_resv_fini(struct dma_resv *obj)
115{
116 struct dma_resv_list *fobj;
117 struct dma_fence *excl;
118
119 /*
120 * This object should be dead and all references must have
121 * been released to it, so no need to be protected with rcu.
122 */
123 excl = rcu_dereference_protected(obj->fence_excl, 1);
124 if (excl)
125 dma_fence_put(excl);
126
127 fobj = rcu_dereference_protected(obj->fence, 1);
128 dma_resv_list_free(fobj);
129 ww_mutex_destroy(&obj->lock);
130}
131EXPORT_SYMBOL(dma_resv_fini);
132
133/**
134 * dma_resv_reserve_shared - Reserve space to add shared fences to
135 * a dma_resv.
136 * @obj: reservation object
137 * @num_fences: number of fences we want to add
138 *
139 * Should be called before dma_resv_add_shared_fence(). Must
140 * be called with obj->lock held.
141 *
142 * RETURNS
143 * Zero for success, or -errno
144 */
145int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences)
146{
147 struct dma_resv_list *old, *new;
148 unsigned int i, j, k, max;
149
150 dma_resv_assert_held(obj);
151
152 old = dma_resv_shared_list(obj);
153 if (old && old->shared_max) {
154 if ((old->shared_count + num_fences) <= old->shared_max)
155 return 0;
156 max = max(old->shared_count + num_fences, old->shared_max * 2);
157 } else {
158 max = max(4ul, roundup_pow_of_two(num_fences));
159 }
160
161 new = dma_resv_list_alloc(max);
162 if (!new)
163 return -ENOMEM;
164
165 /*
166 * no need to bump fence refcounts, rcu_read access
167 * requires the use of kref_get_unless_zero, and the
168 * references from the old struct are carried over to
169 * the new.
170 */
171 for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
172 struct dma_fence *fence;
173
174 fence = rcu_dereference_protected(old->shared[i],
175 dma_resv_held(obj));
176 if (dma_fence_is_signaled(fence))
177 RCU_INIT_POINTER(new->shared[--k], fence);
178 else
179 RCU_INIT_POINTER(new->shared[j++], fence);
180 }
181 new->shared_count = j;
182
183 /*
184 * We are not changing the effective set of fences here so can
185 * merely update the pointer to the new array; both existing
186 * readers and new readers will see exactly the same set of
187 * active (unsignaled) shared fences. Individual fences and the
188 * old array are protected by RCU and so will not vanish under
189 * the gaze of the rcu_read_lock() readers.
190 */
191 rcu_assign_pointer(obj->fence, new);
192
193 if (!old)
194 return 0;
195
196 /* Drop the references to the signaled fences */
197 for (i = k; i < max; ++i) {
198 struct dma_fence *fence;
199
200 fence = rcu_dereference_protected(new->shared[i],
201 dma_resv_held(obj));
202 dma_fence_put(fence);
203 }
204 kfree_rcu(old, rcu);
205
206 return 0;
207}
208EXPORT_SYMBOL(dma_resv_reserve_shared);
209
210#ifdef CONFIG_DEBUG_MUTEXES
211/**
212 * dma_resv_reset_shared_max - reset shared fences for debugging
213 * @obj: the dma_resv object to reset
214 *
215 * Reset the number of pre-reserved shared slots to test that drivers do
216 * correct slot allocation using dma_resv_reserve_shared(). See also
217 * &dma_resv_list.shared_max.
218 */
219void dma_resv_reset_shared_max(struct dma_resv *obj)
220{
221 struct dma_resv_list *fences = dma_resv_shared_list(obj);
222
223 dma_resv_assert_held(obj);
224
225 /* Test shared fence slot reservation */
226 if (fences)
227 fences->shared_max = fences->shared_count;
228}
229EXPORT_SYMBOL(dma_resv_reset_shared_max);
230#endif
231
232/**
233 * dma_resv_add_shared_fence - Add a fence to a shared slot
234 * @obj: the reservation object
235 * @fence: the shared fence to add
236 *
237 * Add a fence to a shared slot, obj->lock must be held, and
238 * dma_resv_reserve_shared() has been called.
239 */
240void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence)
241{
242 struct dma_resv_list *fobj;
243 struct dma_fence *old;
244 unsigned int i, count;
245
246 dma_fence_get(fence);
247
248 dma_resv_assert_held(obj);
249
250 fobj = dma_resv_shared_list(obj);
251 count = fobj->shared_count;
252
253 write_seqcount_begin(&obj->seq);
254
255 for (i = 0; i < count; ++i) {
256
257 old = rcu_dereference_protected(fobj->shared[i],
258 dma_resv_held(obj));
259 if (old->context == fence->context ||
260 dma_fence_is_signaled(old))
261 goto replace;
262 }
263
264 BUG_ON(fobj->shared_count >= fobj->shared_max);
265 old = NULL;
266 count++;
267
268replace:
269 RCU_INIT_POINTER(fobj->shared[i], fence);
270 /* pointer update must be visible before we extend the shared_count */
271 smp_store_mb(fobj->shared_count, count);
272
273 write_seqcount_end(&obj->seq);
274 dma_fence_put(old);
275}
276EXPORT_SYMBOL(dma_resv_add_shared_fence);
277
278/**
279 * dma_resv_add_excl_fence - Add an exclusive fence.
280 * @obj: the reservation object
281 * @fence: the shared fence to add
282 *
283 * Add a fence to the exclusive slot. The obj->lock must be held.
284 */
285void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
286{
287 struct dma_fence *old_fence = dma_resv_excl_fence(obj);
288 struct dma_resv_list *old;
289 u32 i = 0;
290
291 dma_resv_assert_held(obj);
292
293 old = dma_resv_shared_list(obj);
294 if (old)
295 i = old->shared_count;
296
297 if (fence)
298 dma_fence_get(fence);
299
300 write_seqcount_begin(&obj->seq);
301 /* write_seqcount_begin provides the necessary memory barrier */
302 RCU_INIT_POINTER(obj->fence_excl, fence);
303 if (old)
304 old->shared_count = 0;
305 write_seqcount_end(&obj->seq);
306
307 /* inplace update, no shared fences */
308 while (i--)
309 dma_fence_put(rcu_dereference_protected(old->shared[i],
310 dma_resv_held(obj)));
311
312 dma_fence_put(old_fence);
313}
314EXPORT_SYMBOL(dma_resv_add_excl_fence);
315
316/**
317 * dma_resv_copy_fences - Copy all fences from src to dst.
318 * @dst: the destination reservation object
319 * @src: the source reservation object
320 *
321 * Copy all fences from src to dst. dst-lock must be held.
322 */
323int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
324{
325 struct dma_resv_list *src_list, *dst_list;
326 struct dma_fence *old, *new;
327 unsigned int i;
328
329 dma_resv_assert_held(dst);
330
331 rcu_read_lock();
332 src_list = dma_resv_shared_list(src);
333
334retry:
335 if (src_list) {
336 unsigned int shared_count = src_list->shared_count;
337
338 rcu_read_unlock();
339
340 dst_list = dma_resv_list_alloc(shared_count);
341 if (!dst_list)
342 return -ENOMEM;
343
344 rcu_read_lock();
345 src_list = dma_resv_shared_list(src);
346 if (!src_list || src_list->shared_count > shared_count) {
347 kfree(dst_list);
348 goto retry;
349 }
350
351 dst_list->shared_count = 0;
352 for (i = 0; i < src_list->shared_count; ++i) {
353 struct dma_fence __rcu **dst;
354 struct dma_fence *fence;
355
356 fence = rcu_dereference(src_list->shared[i]);
357 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
358 &fence->flags))
359 continue;
360
361 if (!dma_fence_get_rcu(fence)) {
362 dma_resv_list_free(dst_list);
363 src_list = dma_resv_shared_list(src);
364 goto retry;
365 }
366
367 if (dma_fence_is_signaled(fence)) {
368 dma_fence_put(fence);
369 continue;
370 }
371
372 dst = &dst_list->shared[dst_list->shared_count++];
373 rcu_assign_pointer(*dst, fence);
374 }
375 } else {
376 dst_list = NULL;
377 }
378
379 new = dma_fence_get_rcu_safe(&src->fence_excl);
380 rcu_read_unlock();
381
382 src_list = dma_resv_shared_list(dst);
383 old = dma_resv_excl_fence(dst);
384
385 write_seqcount_begin(&dst->seq);
386 /* write_seqcount_begin provides the necessary memory barrier */
387 RCU_INIT_POINTER(dst->fence_excl, new);
388 RCU_INIT_POINTER(dst->fence, dst_list);
389 write_seqcount_end(&dst->seq);
390
391 dma_resv_list_free(src_list);
392 dma_fence_put(old);
393
394 return 0;
395}
396EXPORT_SYMBOL(dma_resv_copy_fences);
397
398/**
399 * dma_resv_get_fences - Get an object's shared and exclusive
400 * fences without update side lock held
401 * @obj: the reservation object
402 * @pfence_excl: the returned exclusive fence (or NULL)
403 * @pshared_count: the number of shared fences returned
404 * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
405 * the required size, and must be freed by caller)
406 *
407 * Retrieve all fences from the reservation object. If the pointer for the
408 * exclusive fence is not specified the fence is put into the array of the
409 * shared fences as well. Returns either zero or -ENOMEM.
410 */
411int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
412 unsigned int *pshared_count,
413 struct dma_fence ***pshared)
414{
415 struct dma_fence **shared = NULL;
416 struct dma_fence *fence_excl;
417 unsigned int shared_count;
418 int ret = 1;
419
420 do {
421 struct dma_resv_list *fobj;
422 unsigned int i, seq;
423 size_t sz = 0;
424
425 shared_count = i = 0;
426
427 rcu_read_lock();
428 seq = read_seqcount_begin(&obj->seq);
429
430 fence_excl = dma_resv_excl_fence(obj);
431 if (fence_excl && !dma_fence_get_rcu(fence_excl))
432 goto unlock;
433
434 fobj = dma_resv_shared_list(obj);
435 if (fobj)
436 sz += sizeof(*shared) * fobj->shared_max;
437
438 if (!pfence_excl && fence_excl)
439 sz += sizeof(*shared);
440
441 if (sz) {
442 struct dma_fence **nshared;
443
444 nshared = krealloc(shared, sz,
445 GFP_NOWAIT | __GFP_NOWARN);
446 if (!nshared) {
447 rcu_read_unlock();
448
449 dma_fence_put(fence_excl);
450 fence_excl = NULL;
451
452 nshared = krealloc(shared, sz, GFP_KERNEL);
453 if (nshared) {
454 shared = nshared;
455 continue;
456 }
457
458 ret = -ENOMEM;
459 break;
460 }
461 shared = nshared;
462 shared_count = fobj ? fobj->shared_count : 0;
463 for (i = 0; i < shared_count; ++i) {
464 shared[i] = rcu_dereference(fobj->shared[i]);
465 if (!dma_fence_get_rcu(shared[i]))
466 break;
467 }
468 }
469
470 if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
471 while (i--)
472 dma_fence_put(shared[i]);
473 dma_fence_put(fence_excl);
474 goto unlock;
475 }
476
477 ret = 0;
478unlock:
479 rcu_read_unlock();
480 } while (ret);
481
482 if (pfence_excl)
483 *pfence_excl = fence_excl;
484 else if (fence_excl)
485 shared[shared_count++] = fence_excl;
486
487 if (!shared_count) {
488 kfree(shared);
489 shared = NULL;
490 }
491
492 *pshared_count = shared_count;
493 *pshared = shared;
494 return ret;
495}
496EXPORT_SYMBOL_GPL(dma_resv_get_fences);
497
498/**
499 * dma_resv_wait_timeout - Wait on reservation's objects
500 * shared and/or exclusive fences.
501 * @obj: the reservation object
502 * @wait_all: if true, wait on all fences, else wait on just exclusive fence
503 * @intr: if true, do interruptible wait
504 * @timeout: timeout value in jiffies or zero to return immediately
505 *
506 * Callers are not required to hold specific locks, but maybe hold
507 * dma_resv_lock() already
508 * RETURNS
509 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
510 * greater than zer on success.
511 */
512long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
513 unsigned long timeout)
514{
515 long ret = timeout ? timeout : 1;
516 unsigned int seq, shared_count;
517 struct dma_fence *fence;
518 int i;
519
520retry:
521 shared_count = 0;
522 seq = read_seqcount_begin(&obj->seq);
523 rcu_read_lock();
524 i = -1;
525
526 fence = dma_resv_excl_fence(obj);
527 if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
528 if (!dma_fence_get_rcu(fence))
529 goto unlock_retry;
530
531 if (dma_fence_is_signaled(fence)) {
532 dma_fence_put(fence);
533 fence = NULL;
534 }
535
536 } else {
537 fence = NULL;
538 }
539
540 if (wait_all) {
541 struct dma_resv_list *fobj = dma_resv_shared_list(obj);
542
543 if (fobj)
544 shared_count = fobj->shared_count;
545
546 for (i = 0; !fence && i < shared_count; ++i) {
547 struct dma_fence *lfence;
548
549 lfence = rcu_dereference(fobj->shared[i]);
550 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
551 &lfence->flags))
552 continue;
553
554 if (!dma_fence_get_rcu(lfence))
555 goto unlock_retry;
556
557 if (dma_fence_is_signaled(lfence)) {
558 dma_fence_put(lfence);
559 continue;
560 }
561
562 fence = lfence;
563 break;
564 }
565 }
566
567 rcu_read_unlock();
568 if (fence) {
569 if (read_seqcount_retry(&obj->seq, seq)) {
570 dma_fence_put(fence);
571 goto retry;
572 }
573
574 ret = dma_fence_wait_timeout(fence, intr, ret);
575 dma_fence_put(fence);
576 if (ret > 0 && wait_all && (i + 1 < shared_count))
577 goto retry;
578 }
579 return ret;
580
581unlock_retry:
582 rcu_read_unlock();
583 goto retry;
584}
585EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
586
587
588static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
589{
590 struct dma_fence *fence, *lfence = passed_fence;
591 int ret = 1;
592
593 if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
594 fence = dma_fence_get_rcu(lfence);
595 if (!fence)
596 return -1;
597
598 ret = !!dma_fence_is_signaled(fence);
599 dma_fence_put(fence);
600 }
601 return ret;
602}
603
604/**
605 * dma_resv_test_signaled - Test if a reservation object's fences have been
606 * signaled.
607 * @obj: the reservation object
608 * @test_all: if true, test all fences, otherwise only test the exclusive
609 * fence
610 *
611 * Callers are not required to hold specific locks, but maybe hold
612 * dma_resv_lock() already
613 * RETURNS
614 * true if all fences signaled, else false
615 */
616bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all)
617{
618 struct dma_fence *fence;
619 unsigned int seq;
620 int ret;
621
622 rcu_read_lock();
623retry:
624 ret = true;
625 seq = read_seqcount_begin(&obj->seq);
626
627 if (test_all) {
628 struct dma_resv_list *fobj = dma_resv_shared_list(obj);
629 unsigned int i, shared_count;
630
631 shared_count = fobj ? fobj->shared_count : 0;
632 for (i = 0; i < shared_count; ++i) {
633 fence = rcu_dereference(fobj->shared[i]);
634 ret = dma_resv_test_signaled_single(fence);
635 if (ret < 0)
636 goto retry;
637 else if (!ret)
638 break;
639 }
640 }
641
642 fence = dma_resv_excl_fence(obj);
643 if (ret && fence) {
644 ret = dma_resv_test_signaled_single(fence);
645 if (ret < 0)
646 goto retry;
647
648 }
649
650 if (read_seqcount_retry(&obj->seq, seq))
651 goto retry;
652
653 rcu_read_unlock();
654 return ret;
655}
656EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
657
658#if IS_ENABLED(CONFIG_LOCKDEP)
659static int __init dma_resv_lockdep(void)
660{
661 struct mm_struct *mm = mm_alloc();
662 struct ww_acquire_ctx ctx;
663 struct dma_resv obj;
664 struct address_space mapping;
665 int ret;
666
667 if (!mm)
668 return -ENOMEM;
669
670 dma_resv_init(&obj);
671 address_space_init_once(&mapping);
672
673 mmap_read_lock(mm);
674 ww_acquire_init(&ctx, &reservation_ww_class);
675 ret = dma_resv_lock(&obj, &ctx);
676 if (ret == -EDEADLK)
677 dma_resv_lock_slow(&obj, &ctx);
678 fs_reclaim_acquire(GFP_KERNEL);
679 /* for unmap_mapping_range on trylocked buffer objects in shrinkers */
680 i_mmap_lock_write(&mapping);
681 i_mmap_unlock_write(&mapping);
682#ifdef CONFIG_MMU_NOTIFIER
683 lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
684 __dma_fence_might_wait();
685 lock_map_release(&__mmu_notifier_invalidate_range_start_map);
686#else
687 __dma_fence_might_wait();
688#endif
689 fs_reclaim_release(GFP_KERNEL);
690 ww_mutex_unlock(&obj.lock);
691 ww_acquire_fini(&ctx);
692 mmap_read_unlock(mm);
693
694 mmput(mm);
695
696 return 0;
697}
698subsys_initcall(dma_resv_lockdep);
699#endif