xref: /openbmc/linux/drivers/dma-buf/dma-resv.c (revision acf50233)
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 
57 DEFINE_WD_CLASS(reservation_ww_class);
58 EXPORT_SYMBOL(reservation_ww_class);
59 
60 /* Mask for the lower fence pointer bits */
61 #define DMA_RESV_LIST_MASK	0x3
62 
63 struct 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. */
70 static 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. */
84 static 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  */
98 static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences)
99 {
100 	struct dma_resv_list *list;
101 
102 	list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL);
103 	if (!list)
104 		return NULL;
105 
106 	list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) /
107 		sizeof(*list->table);
108 
109 	return list;
110 }
111 
112 /* Free a dma_resv_list and make sure to drop all references. */
113 static void dma_resv_list_free(struct dma_resv_list *list)
114 {
115 	unsigned int i;
116 
117 	if (!list)
118 		return;
119 
120 	for (i = 0; i < list->num_fences; ++i) {
121 		struct dma_fence *fence;
122 
123 		dma_resv_list_entry(list, i, NULL, &fence, NULL);
124 		dma_fence_put(fence);
125 	}
126 	kfree_rcu(list, rcu);
127 }
128 
129 /**
130  * dma_resv_init - initialize a reservation object
131  * @obj: the reservation object
132  */
133 void dma_resv_init(struct dma_resv *obj)
134 {
135 	ww_mutex_init(&obj->lock, &reservation_ww_class);
136 
137 	RCU_INIT_POINTER(obj->fences, NULL);
138 }
139 EXPORT_SYMBOL(dma_resv_init);
140 
141 /**
142  * dma_resv_fini - destroys a reservation object
143  * @obj: the reservation object
144  */
145 void dma_resv_fini(struct dma_resv *obj)
146 {
147 	/*
148 	 * This object should be dead and all references must have
149 	 * been released to it, so no need to be protected with rcu.
150 	 */
151 	dma_resv_list_free(rcu_dereference_protected(obj->fences, true));
152 	ww_mutex_destroy(&obj->lock);
153 }
154 EXPORT_SYMBOL(dma_resv_fini);
155 
156 /* Dereference the fences while ensuring RCU rules */
157 static inline struct dma_resv_list *dma_resv_fences_list(struct dma_resv *obj)
158 {
159 	return rcu_dereference_check(obj->fences, dma_resv_held(obj));
160 }
161 
162 /**
163  * dma_resv_reserve_fences - Reserve space to add fences to a dma_resv object.
164  * @obj: reservation object
165  * @num_fences: number of fences we want to add
166  *
167  * Should be called before dma_resv_add_fence().  Must be called with @obj
168  * locked through dma_resv_lock().
169  *
170  * Note that the preallocated slots need to be re-reserved if @obj is unlocked
171  * at any time before calling dma_resv_add_fence(). This is validated when
172  * CONFIG_DEBUG_MUTEXES is enabled.
173  *
174  * RETURNS
175  * Zero for success, or -errno
176  */
177 int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences)
178 {
179 	struct dma_resv_list *old, *new;
180 	unsigned int i, j, k, max;
181 
182 	dma_resv_assert_held(obj);
183 
184 	old = dma_resv_fences_list(obj);
185 	if (old && old->max_fences) {
186 		if ((old->num_fences + num_fences) <= old->max_fences)
187 			return 0;
188 		max = max(old->num_fences + num_fences, old->max_fences * 2);
189 	} else {
190 		max = max(4ul, roundup_pow_of_two(num_fences));
191 	}
192 
193 	new = dma_resv_list_alloc(max);
194 	if (!new)
195 		return -ENOMEM;
196 
197 	/*
198 	 * no need to bump fence refcounts, rcu_read access
199 	 * requires the use of kref_get_unless_zero, and the
200 	 * references from the old struct are carried over to
201 	 * the new.
202 	 */
203 	for (i = 0, j = 0, k = max; i < (old ? old->num_fences : 0); ++i) {
204 		enum dma_resv_usage usage;
205 		struct dma_fence *fence;
206 
207 		dma_resv_list_entry(old, i, obj, &fence, &usage);
208 		if (dma_fence_is_signaled(fence))
209 			RCU_INIT_POINTER(new->table[--k], fence);
210 		else
211 			dma_resv_list_set(new, j++, fence, usage);
212 	}
213 	new->num_fences = j;
214 
215 	/*
216 	 * We are not changing the effective set of fences here so can
217 	 * merely update the pointer to the new array; both existing
218 	 * readers and new readers will see exactly the same set of
219 	 * active (unsignaled) fences. Individual fences and the
220 	 * old array are protected by RCU and so will not vanish under
221 	 * the gaze of the rcu_read_lock() readers.
222 	 */
223 	rcu_assign_pointer(obj->fences, new);
224 
225 	if (!old)
226 		return 0;
227 
228 	/* Drop the references to the signaled fences */
229 	for (i = k; i < max; ++i) {
230 		struct dma_fence *fence;
231 
232 		fence = rcu_dereference_protected(new->table[i],
233 						  dma_resv_held(obj));
234 		dma_fence_put(fence);
235 	}
236 	kfree_rcu(old, rcu);
237 
238 	return 0;
239 }
240 EXPORT_SYMBOL(dma_resv_reserve_fences);
241 
242 #ifdef CONFIG_DEBUG_MUTEXES
243 /**
244  * dma_resv_reset_max_fences - reset fences for debugging
245  * @obj: the dma_resv object to reset
246  *
247  * Reset the number of pre-reserved fence slots to test that drivers do
248  * correct slot allocation using dma_resv_reserve_fences(). See also
249  * &dma_resv_list.max_fences.
250  */
251 void dma_resv_reset_max_fences(struct dma_resv *obj)
252 {
253 	struct dma_resv_list *fences = dma_resv_fences_list(obj);
254 
255 	dma_resv_assert_held(obj);
256 
257 	/* Test fence slot reservation */
258 	if (fences)
259 		fences->max_fences = fences->num_fences;
260 }
261 EXPORT_SYMBOL(dma_resv_reset_max_fences);
262 #endif
263 
264 /**
265  * dma_resv_add_fence - Add a fence to the dma_resv obj
266  * @obj: the reservation object
267  * @fence: the fence to add
268  * @usage: how the fence is used, see enum dma_resv_usage
269  *
270  * Add a fence to a slot, @obj must be locked with dma_resv_lock(), and
271  * dma_resv_reserve_fences() has been called.
272  *
273  * See also &dma_resv.fence for a discussion of the semantics.
274  */
275 void dma_resv_add_fence(struct dma_resv *obj, struct dma_fence *fence,
276 			enum dma_resv_usage usage)
277 {
278 	struct dma_resv_list *fobj;
279 	struct dma_fence *old;
280 	unsigned int i, count;
281 
282 	dma_fence_get(fence);
283 
284 	dma_resv_assert_held(obj);
285 
286 	/* Drivers should not add containers here, instead add each fence
287 	 * individually.
288 	 */
289 	WARN_ON(dma_fence_is_container(fence));
290 
291 	fobj = dma_resv_fences_list(obj);
292 	count = fobj->num_fences;
293 
294 	for (i = 0; i < count; ++i) {
295 		enum dma_resv_usage old_usage;
296 
297 		dma_resv_list_entry(fobj, i, obj, &old, &old_usage);
298 		if ((old->context == fence->context && old_usage >= usage) ||
299 		    dma_fence_is_signaled(old)) {
300 			dma_resv_list_set(fobj, i, fence, usage);
301 			dma_fence_put(old);
302 			return;
303 		}
304 	}
305 
306 	BUG_ON(fobj->num_fences >= fobj->max_fences);
307 	count++;
308 
309 	dma_resv_list_set(fobj, i, fence, usage);
310 	/* pointer update must be visible before we extend the num_fences */
311 	smp_store_mb(fobj->num_fences, count);
312 }
313 EXPORT_SYMBOL(dma_resv_add_fence);
314 
315 /**
316  * dma_resv_replace_fences - replace fences in the dma_resv obj
317  * @obj: the reservation object
318  * @context: the context of the fences to replace
319  * @replacement: the new fence to use instead
320  * @usage: how the new fence is used, see enum dma_resv_usage
321  *
322  * Replace fences with a specified context with a new fence. Only valid if the
323  * operation represented by the original fence has no longer access to the
324  * resources represented by the dma_resv object when the new fence completes.
325  *
326  * And example for using this is replacing a preemption fence with a page table
327  * update fence which makes the resource inaccessible.
328  */
329 void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
330 			     struct dma_fence *replacement,
331 			     enum dma_resv_usage usage)
332 {
333 	struct dma_resv_list *list;
334 	unsigned int i;
335 
336 	dma_resv_assert_held(obj);
337 
338 	list = dma_resv_fences_list(obj);
339 	for (i = 0; list && i < list->num_fences; ++i) {
340 		struct dma_fence *old;
341 
342 		dma_resv_list_entry(list, i, obj, &old, NULL);
343 		if (old->context != context)
344 			continue;
345 
346 		dma_resv_list_set(list, i, replacement, usage);
347 		dma_fence_put(old);
348 	}
349 }
350 EXPORT_SYMBOL(dma_resv_replace_fences);
351 
352 /* Restart the unlocked iteration by initializing the cursor object. */
353 static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
354 {
355 	cursor->index = 0;
356 	cursor->num_fences = 0;
357 	cursor->fences = dma_resv_fences_list(cursor->obj);
358 	if (cursor->fences)
359 		cursor->num_fences = cursor->fences->num_fences;
360 	cursor->is_restarted = true;
361 }
362 
363 /* Walk to the next not signaled fence and grab a reference to it */
364 static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
365 {
366 	if (!cursor->fences)
367 		return;
368 
369 	do {
370 		/* Drop the reference from the previous round */
371 		dma_fence_put(cursor->fence);
372 
373 		if (cursor->index >= cursor->num_fences) {
374 			cursor->fence = NULL;
375 			break;
376 
377 		}
378 
379 		dma_resv_list_entry(cursor->fences, cursor->index++,
380 				    cursor->obj, &cursor->fence,
381 				    &cursor->fence_usage);
382 		cursor->fence = dma_fence_get_rcu(cursor->fence);
383 		if (!cursor->fence) {
384 			dma_resv_iter_restart_unlocked(cursor);
385 			continue;
386 		}
387 
388 		if (!dma_fence_is_signaled(cursor->fence) &&
389 		    cursor->usage >= cursor->fence_usage)
390 			break;
391 	} while (true);
392 }
393 
394 /**
395  * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
396  * @cursor: the cursor with the current position
397  *
398  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
399  *
400  * Beware that the iterator can be restarted.  Code which accumulates statistics
401  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
402  * this reason prefer the locked dma_resv_iter_first() whenver possible.
403  *
404  * Returns the first fence from an unlocked dma_resv obj.
405  */
406 struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
407 {
408 	rcu_read_lock();
409 	do {
410 		dma_resv_iter_restart_unlocked(cursor);
411 		dma_resv_iter_walk_unlocked(cursor);
412 	} while (dma_resv_fences_list(cursor->obj) != cursor->fences);
413 	rcu_read_unlock();
414 
415 	return cursor->fence;
416 }
417 EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
418 
419 /**
420  * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
421  * @cursor: the cursor with the current position
422  *
423  * Beware that the iterator can be restarted.  Code which accumulates statistics
424  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
425  * this reason prefer the locked dma_resv_iter_next() whenver possible.
426  *
427  * Returns the next fence from an unlocked dma_resv obj.
428  */
429 struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
430 {
431 	bool restart;
432 
433 	rcu_read_lock();
434 	cursor->is_restarted = false;
435 	restart = dma_resv_fences_list(cursor->obj) != cursor->fences;
436 	do {
437 		if (restart)
438 			dma_resv_iter_restart_unlocked(cursor);
439 		dma_resv_iter_walk_unlocked(cursor);
440 		restart = true;
441 	} while (dma_resv_fences_list(cursor->obj) != cursor->fences);
442 	rcu_read_unlock();
443 
444 	return cursor->fence;
445 }
446 EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
447 
448 /**
449  * dma_resv_iter_first - first fence from a locked dma_resv object
450  * @cursor: cursor to record the current position
451  *
452  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
453  *
454  * Return the first fence in the dma_resv object while holding the
455  * &dma_resv.lock.
456  */
457 struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
458 {
459 	struct dma_fence *fence;
460 
461 	dma_resv_assert_held(cursor->obj);
462 
463 	cursor->index = 0;
464 	cursor->fences = dma_resv_fences_list(cursor->obj);
465 
466 	fence = dma_resv_iter_next(cursor);
467 	cursor->is_restarted = true;
468 	return fence;
469 }
470 EXPORT_SYMBOL_GPL(dma_resv_iter_first);
471 
472 /**
473  * dma_resv_iter_next - next fence from a locked dma_resv object
474  * @cursor: cursor to record the current position
475  *
476  * Return the next fences from the dma_resv object while holding the
477  * &dma_resv.lock.
478  */
479 struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
480 {
481 	struct dma_fence *fence;
482 
483 	dma_resv_assert_held(cursor->obj);
484 
485 	cursor->is_restarted = false;
486 
487 	do {
488 		if (!cursor->fences ||
489 		    cursor->index >= cursor->fences->num_fences)
490 			return NULL;
491 
492 		dma_resv_list_entry(cursor->fences, cursor->index++,
493 				    cursor->obj, &fence, &cursor->fence_usage);
494 	} while (cursor->fence_usage > cursor->usage);
495 
496 	return fence;
497 }
498 EXPORT_SYMBOL_GPL(dma_resv_iter_next);
499 
500 /**
501  * dma_resv_copy_fences - Copy all fences from src to dst.
502  * @dst: the destination reservation object
503  * @src: the source reservation object
504  *
505  * Copy all fences from src to dst. dst-lock must be held.
506  */
507 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
508 {
509 	struct dma_resv_iter cursor;
510 	struct dma_resv_list *list;
511 	struct dma_fence *f;
512 
513 	dma_resv_assert_held(dst);
514 
515 	list = NULL;
516 
517 	dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP);
518 	dma_resv_for_each_fence_unlocked(&cursor, f) {
519 
520 		if (dma_resv_iter_is_restarted(&cursor)) {
521 			dma_resv_list_free(list);
522 
523 			list = dma_resv_list_alloc(cursor.num_fences);
524 			if (!list) {
525 				dma_resv_iter_end(&cursor);
526 				return -ENOMEM;
527 			}
528 			list->num_fences = 0;
529 		}
530 
531 		dma_fence_get(f);
532 		dma_resv_list_set(list, list->num_fences++, f,
533 				  dma_resv_iter_usage(&cursor));
534 	}
535 	dma_resv_iter_end(&cursor);
536 
537 	list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
538 	dma_resv_list_free(list);
539 	return 0;
540 }
541 EXPORT_SYMBOL(dma_resv_copy_fences);
542 
543 /**
544  * dma_resv_get_fences - Get an object's fences
545  * fences without update side lock held
546  * @obj: the reservation object
547  * @usage: controls which fences to include, see enum dma_resv_usage.
548  * @num_fences: the number of fences returned
549  * @fences: the array of fence ptrs returned (array is krealloc'd to the
550  * required size, and must be freed by caller)
551  *
552  * Retrieve all fences from the reservation object.
553  * Returns either zero or -ENOMEM.
554  */
555 int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
556 			unsigned int *num_fences, struct dma_fence ***fences)
557 {
558 	struct dma_resv_iter cursor;
559 	struct dma_fence *fence;
560 
561 	*num_fences = 0;
562 	*fences = NULL;
563 
564 	dma_resv_iter_begin(&cursor, obj, usage);
565 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
566 
567 		if (dma_resv_iter_is_restarted(&cursor)) {
568 			unsigned int count;
569 
570 			while (*num_fences)
571 				dma_fence_put((*fences)[--(*num_fences)]);
572 
573 			count = cursor.num_fences + 1;
574 
575 			/* Eventually re-allocate the array */
576 			*fences = krealloc_array(*fences, count,
577 						 sizeof(void *),
578 						 GFP_KERNEL);
579 			if (count && !*fences) {
580 				dma_resv_iter_end(&cursor);
581 				return -ENOMEM;
582 			}
583 		}
584 
585 		(*fences)[(*num_fences)++] = dma_fence_get(fence);
586 	}
587 	dma_resv_iter_end(&cursor);
588 
589 	return 0;
590 }
591 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
592 
593 /**
594  * dma_resv_get_singleton - Get a single fence for all the fences
595  * @obj: the reservation object
596  * @usage: controls which fences to include, see enum dma_resv_usage.
597  * @fence: the resulting fence
598  *
599  * Get a single fence representing all the fences inside the resv object.
600  * Returns either 0 for success or -ENOMEM.
601  *
602  * Warning: This can't be used like this when adding the fence back to the resv
603  * object since that can lead to stack corruption when finalizing the
604  * dma_fence_array.
605  *
606  * Returns 0 on success and negative error values on failure.
607  */
608 int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
609 			   struct dma_fence **fence)
610 {
611 	struct dma_fence_array *array;
612 	struct dma_fence **fences;
613 	unsigned count;
614 	int r;
615 
616 	r = dma_resv_get_fences(obj, usage, &count, &fences);
617         if (r)
618 		return r;
619 
620 	if (count == 0) {
621 		*fence = NULL;
622 		return 0;
623 	}
624 
625 	if (count == 1) {
626 		*fence = fences[0];
627 		kfree(fences);
628 		return 0;
629 	}
630 
631 	array = dma_fence_array_create(count, fences,
632 				       dma_fence_context_alloc(1),
633 				       1, false);
634 	if (!array) {
635 		while (count--)
636 			dma_fence_put(fences[count]);
637 		kfree(fences);
638 		return -ENOMEM;
639 	}
640 
641 	*fence = &array->base;
642 	return 0;
643 }
644 EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
645 
646 /**
647  * dma_resv_wait_timeout - Wait on reservation's objects fences
648  * @obj: the reservation object
649  * @usage: controls which fences to include, see enum dma_resv_usage.
650  * @intr: if true, do interruptible wait
651  * @timeout: timeout value in jiffies or zero to return immediately
652  *
653  * Callers are not required to hold specific locks, but maybe hold
654  * dma_resv_lock() already
655  * RETURNS
656  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
657  * greater than zer on success.
658  */
659 long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
660 			   bool intr, unsigned long timeout)
661 {
662 	long ret = timeout ? timeout : 1;
663 	struct dma_resv_iter cursor;
664 	struct dma_fence *fence;
665 
666 	dma_resv_iter_begin(&cursor, obj, usage);
667 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
668 
669 		ret = dma_fence_wait_timeout(fence, intr, ret);
670 		if (ret <= 0) {
671 			dma_resv_iter_end(&cursor);
672 			return ret;
673 		}
674 	}
675 	dma_resv_iter_end(&cursor);
676 
677 	return ret;
678 }
679 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
680 
681 
682 /**
683  * dma_resv_test_signaled - Test if a reservation object's fences have been
684  * signaled.
685  * @obj: the reservation object
686  * @usage: controls which fences to include, see enum dma_resv_usage.
687  *
688  * Callers are not required to hold specific locks, but maybe hold
689  * dma_resv_lock() already.
690  *
691  * RETURNS
692  *
693  * True if all fences signaled, else false.
694  */
695 bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage)
696 {
697 	struct dma_resv_iter cursor;
698 	struct dma_fence *fence;
699 
700 	dma_resv_iter_begin(&cursor, obj, usage);
701 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
702 		dma_resv_iter_end(&cursor);
703 		return false;
704 	}
705 	dma_resv_iter_end(&cursor);
706 	return true;
707 }
708 EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
709 
710 /**
711  * dma_resv_describe - Dump description of the resv object into seq_file
712  * @obj: the reservation object
713  * @seq: the seq_file to dump the description into
714  *
715  * Dump a textual description of the fences inside an dma_resv object into the
716  * seq_file.
717  */
718 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
719 {
720 	static const char *usage[] = { "kernel", "write", "read", "bookkeep" };
721 	struct dma_resv_iter cursor;
722 	struct dma_fence *fence;
723 
724 	dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
725 		seq_printf(seq, "\t%s fence:",
726 			   usage[dma_resv_iter_usage(&cursor)]);
727 		dma_fence_describe(fence, seq);
728 	}
729 }
730 EXPORT_SYMBOL_GPL(dma_resv_describe);
731 
732 #if IS_ENABLED(CONFIG_LOCKDEP)
733 static int __init dma_resv_lockdep(void)
734 {
735 	struct mm_struct *mm = mm_alloc();
736 	struct ww_acquire_ctx ctx;
737 	struct dma_resv obj;
738 	struct address_space mapping;
739 	int ret;
740 
741 	if (!mm)
742 		return -ENOMEM;
743 
744 	dma_resv_init(&obj);
745 	address_space_init_once(&mapping);
746 
747 	mmap_read_lock(mm);
748 	ww_acquire_init(&ctx, &reservation_ww_class);
749 	ret = dma_resv_lock(&obj, &ctx);
750 	if (ret == -EDEADLK)
751 		dma_resv_lock_slow(&obj, &ctx);
752 	fs_reclaim_acquire(GFP_KERNEL);
753 	/* for unmap_mapping_range on trylocked buffer objects in shrinkers */
754 	i_mmap_lock_write(&mapping);
755 	i_mmap_unlock_write(&mapping);
756 #ifdef CONFIG_MMU_NOTIFIER
757 	lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
758 	__dma_fence_might_wait();
759 	lock_map_release(&__mmu_notifier_invalidate_range_start_map);
760 #else
761 	__dma_fence_might_wait();
762 #endif
763 	fs_reclaim_release(GFP_KERNEL);
764 	ww_mutex_unlock(&obj.lock);
765 	ww_acquire_fini(&ctx);
766 	mmap_read_unlock(mm);
767 
768 	mmput(mm);
769 
770 	return 0;
771 }
772 subsys_initcall(dma_resv_lockdep);
773 #endif
774