xref: /openbmc/linux/drivers/dma-buf/dma-resv.c (revision 5f1a233e)
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. */
dma_resv_list_entry(struct dma_resv_list * list,unsigned int index,struct dma_resv * resv,struct dma_fence ** fence,enum dma_resv_usage * usage)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. */
dma_resv_list_set(struct dma_resv_list * list,unsigned int index,struct dma_fence * fence,enum dma_resv_usage usage)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  */
dma_resv_list_alloc(unsigned int max_fences)98 static 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. */
dma_resv_list_free(struct dma_resv_list * list)118 static 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  */
dma_resv_init(struct dma_resv * obj)138 void 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 }
144 EXPORT_SYMBOL(dma_resv_init);
145 
146 /**
147  * dma_resv_fini - destroys a reservation object
148  * @obj: the reservation object
149  */
dma_resv_fini(struct dma_resv * obj)150 void 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 }
159 EXPORT_SYMBOL(dma_resv_fini);
160 
161 /* Dereference the fences while ensuring RCU rules */
dma_resv_fences_list(struct dma_resv * obj)162 static 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  */
dma_resv_reserve_fences(struct dma_resv * obj,unsigned int num_fences)182 int 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 }
245 EXPORT_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  */
dma_resv_reset_max_fences(struct dma_resv * obj)256 void 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 }
266 EXPORT_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  */
dma_resv_add_fence(struct dma_resv * obj,struct dma_fence * fence,enum dma_resv_usage usage)280 void 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 }
319 EXPORT_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  */
dma_resv_replace_fences(struct dma_resv * obj,uint64_t context,struct dma_fence * replacement,enum dma_resv_usage usage)335 void 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 }
356 EXPORT_SYMBOL(dma_resv_replace_fences);
357 
358 /* Restart the unlocked iteration by initializing the cursor object. */
dma_resv_iter_restart_unlocked(struct dma_resv_iter * cursor)359 static 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 */
dma_resv_iter_walk_unlocked(struct dma_resv_iter * cursor)370 static 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  */
dma_resv_iter_first_unlocked(struct dma_resv_iter * cursor)412 struct 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 }
423 EXPORT_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  */
dma_resv_iter_next_unlocked(struct dma_resv_iter * cursor)435 struct 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 }
452 EXPORT_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  */
dma_resv_iter_first(struct dma_resv_iter * cursor)463 struct 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 }
476 EXPORT_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  */
dma_resv_iter_next(struct dma_resv_iter * cursor)485 struct 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 }
504 EXPORT_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  */
dma_resv_copy_fences(struct dma_resv * dst,struct dma_resv * src)513 int 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 }
547 EXPORT_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  */
dma_resv_get_fences(struct dma_resv * obj,enum dma_resv_usage usage,unsigned int * num_fences,struct dma_fence *** fences)561 int 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 }
602 EXPORT_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  */
dma_resv_get_singleton(struct dma_resv * obj,enum dma_resv_usage usage,struct dma_fence ** fence)619 int 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 }
655 EXPORT_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  */
dma_resv_wait_timeout(struct dma_resv * obj,enum dma_resv_usage usage,bool intr,unsigned long timeout)670 long 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 }
690 EXPORT_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  */
dma_resv_set_deadline(struct dma_resv * obj,enum dma_resv_usage usage,ktime_t deadline)701 void 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 }
713 EXPORT_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  */
dma_resv_test_signaled(struct dma_resv * obj,enum dma_resv_usage usage)728 bool 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 }
741 EXPORT_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  */
dma_resv_describe(struct dma_resv * obj,struct seq_file * seq)751 void 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 }
763 EXPORT_SYMBOL_GPL(dma_resv_describe);
764 
765 #if IS_ENABLED(CONFIG_LOCKDEP)
dma_resv_lockdep(void)766 static 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 }
805 subsys_initcall(dma_resv_lockdep);
806 #endif
807