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 
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. */
dma_resv_list_free(struct dma_resv_list * list)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  */
dma_resv_init(struct dma_resv * obj)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  */
dma_resv_fini(struct dma_resv * obj)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 */
dma_resv_fences_list(struct dma_resv * obj)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  */
dma_resv_reserve_fences(struct dma_resv * obj,unsigned int num_fences)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  */
dma_resv_reset_max_fences(struct dma_resv * obj)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  */
dma_resv_add_fence(struct dma_resv * obj,struct dma_fence * fence,enum dma_resv_usage usage)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_later(fence, old)) ||
300 		    dma_fence_is_signaled(old)) {
301 			dma_resv_list_set(fobj, i, fence, usage);
302 			dma_fence_put(old);
303 			return;
304 		}
305 	}
306 
307 	BUG_ON(fobj->num_fences >= fobj->max_fences);
308 	count++;
309 
310 	dma_resv_list_set(fobj, i, fence, usage);
311 	/* pointer update must be visible before we extend the num_fences */
312 	smp_store_mb(fobj->num_fences, count);
313 }
314 EXPORT_SYMBOL(dma_resv_add_fence);
315 
316 /**
317  * dma_resv_replace_fences - replace fences in the dma_resv obj
318  * @obj: the reservation object
319  * @context: the context of the fences to replace
320  * @replacement: the new fence to use instead
321  * @usage: how the new fence is used, see enum dma_resv_usage
322  *
323  * Replace fences with a specified context with a new fence. Only valid if the
324  * operation represented by the original fence has no longer access to the
325  * resources represented by the dma_resv object when the new fence completes.
326  *
327  * And example for using this is replacing a preemption fence with a page table
328  * update fence which makes the resource inaccessible.
329  */
dma_resv_replace_fences(struct dma_resv * obj,uint64_t context,struct dma_fence * replacement,enum dma_resv_usage usage)330 void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
331 			     struct dma_fence *replacement,
332 			     enum dma_resv_usage usage)
333 {
334 	struct dma_resv_list *list;
335 	unsigned int i;
336 
337 	dma_resv_assert_held(obj);
338 
339 	list = dma_resv_fences_list(obj);
340 	for (i = 0; list && i < list->num_fences; ++i) {
341 		struct dma_fence *old;
342 
343 		dma_resv_list_entry(list, i, obj, &old, NULL);
344 		if (old->context != context)
345 			continue;
346 
347 		dma_resv_list_set(list, i, dma_fence_get(replacement), usage);
348 		dma_fence_put(old);
349 	}
350 }
351 EXPORT_SYMBOL(dma_resv_replace_fences);
352 
353 /* Restart the unlocked iteration by initializing the cursor object. */
dma_resv_iter_restart_unlocked(struct dma_resv_iter * cursor)354 static void dma_resv_iter_restart_unlocked(struct dma_resv_iter *cursor)
355 {
356 	cursor->index = 0;
357 	cursor->num_fences = 0;
358 	cursor->fences = dma_resv_fences_list(cursor->obj);
359 	if (cursor->fences)
360 		cursor->num_fences = cursor->fences->num_fences;
361 	cursor->is_restarted = true;
362 }
363 
364 /* Walk to the next not signaled fence and grab a reference to it */
dma_resv_iter_walk_unlocked(struct dma_resv_iter * cursor)365 static void dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor)
366 {
367 	if (!cursor->fences)
368 		return;
369 
370 	do {
371 		/* Drop the reference from the previous round */
372 		dma_fence_put(cursor->fence);
373 
374 		if (cursor->index >= cursor->num_fences) {
375 			cursor->fence = NULL;
376 			break;
377 
378 		}
379 
380 		dma_resv_list_entry(cursor->fences, cursor->index++,
381 				    cursor->obj, &cursor->fence,
382 				    &cursor->fence_usage);
383 		cursor->fence = dma_fence_get_rcu(cursor->fence);
384 		if (!cursor->fence) {
385 			dma_resv_iter_restart_unlocked(cursor);
386 			continue;
387 		}
388 
389 		if (!dma_fence_is_signaled(cursor->fence) &&
390 		    cursor->usage >= cursor->fence_usage)
391 			break;
392 	} while (true);
393 }
394 
395 /**
396  * dma_resv_iter_first_unlocked - first fence in an unlocked dma_resv obj.
397  * @cursor: the cursor with the current position
398  *
399  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
400  *
401  * Beware that the iterator can be restarted.  Code which accumulates statistics
402  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
403  * this reason prefer the locked dma_resv_iter_first() whenver possible.
404  *
405  * Returns the first fence from an unlocked dma_resv obj.
406  */
dma_resv_iter_first_unlocked(struct dma_resv_iter * cursor)407 struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor)
408 {
409 	rcu_read_lock();
410 	do {
411 		dma_resv_iter_restart_unlocked(cursor);
412 		dma_resv_iter_walk_unlocked(cursor);
413 	} while (dma_resv_fences_list(cursor->obj) != cursor->fences);
414 	rcu_read_unlock();
415 
416 	return cursor->fence;
417 }
418 EXPORT_SYMBOL(dma_resv_iter_first_unlocked);
419 
420 /**
421  * dma_resv_iter_next_unlocked - next fence in an unlocked dma_resv obj.
422  * @cursor: the cursor with the current position
423  *
424  * Beware that the iterator can be restarted.  Code which accumulates statistics
425  * or similar needs to check for this with dma_resv_iter_is_restarted(). For
426  * this reason prefer the locked dma_resv_iter_next() whenver possible.
427  *
428  * Returns the next fence from an unlocked dma_resv obj.
429  */
dma_resv_iter_next_unlocked(struct dma_resv_iter * cursor)430 struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
431 {
432 	bool restart;
433 
434 	rcu_read_lock();
435 	cursor->is_restarted = false;
436 	restart = dma_resv_fences_list(cursor->obj) != cursor->fences;
437 	do {
438 		if (restart)
439 			dma_resv_iter_restart_unlocked(cursor);
440 		dma_resv_iter_walk_unlocked(cursor);
441 		restart = true;
442 	} while (dma_resv_fences_list(cursor->obj) != cursor->fences);
443 	rcu_read_unlock();
444 
445 	return cursor->fence;
446 }
447 EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
448 
449 /**
450  * dma_resv_iter_first - first fence from a locked dma_resv object
451  * @cursor: cursor to record the current position
452  *
453  * Subsequent fences are iterated with dma_resv_iter_next_unlocked().
454  *
455  * Return the first fence in the dma_resv object while holding the
456  * &dma_resv.lock.
457  */
dma_resv_iter_first(struct dma_resv_iter * cursor)458 struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
459 {
460 	struct dma_fence *fence;
461 
462 	dma_resv_assert_held(cursor->obj);
463 
464 	cursor->index = 0;
465 	cursor->fences = dma_resv_fences_list(cursor->obj);
466 
467 	fence = dma_resv_iter_next(cursor);
468 	cursor->is_restarted = true;
469 	return fence;
470 }
471 EXPORT_SYMBOL_GPL(dma_resv_iter_first);
472 
473 /**
474  * dma_resv_iter_next - next fence from a locked dma_resv object
475  * @cursor: cursor to record the current position
476  *
477  * Return the next fences from the dma_resv object while holding the
478  * &dma_resv.lock.
479  */
dma_resv_iter_next(struct dma_resv_iter * cursor)480 struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
481 {
482 	struct dma_fence *fence;
483 
484 	dma_resv_assert_held(cursor->obj);
485 
486 	cursor->is_restarted = false;
487 
488 	do {
489 		if (!cursor->fences ||
490 		    cursor->index >= cursor->fences->num_fences)
491 			return NULL;
492 
493 		dma_resv_list_entry(cursor->fences, cursor->index++,
494 				    cursor->obj, &fence, &cursor->fence_usage);
495 	} while (cursor->fence_usage > cursor->usage);
496 
497 	return fence;
498 }
499 EXPORT_SYMBOL_GPL(dma_resv_iter_next);
500 
501 /**
502  * dma_resv_copy_fences - Copy all fences from src to dst.
503  * @dst: the destination reservation object
504  * @src: the source reservation object
505  *
506  * Copy all fences from src to dst. dst-lock must be held.
507  */
dma_resv_copy_fences(struct dma_resv * dst,struct dma_resv * src)508 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
509 {
510 	struct dma_resv_iter cursor;
511 	struct dma_resv_list *list;
512 	struct dma_fence *f;
513 
514 	dma_resv_assert_held(dst);
515 
516 	list = NULL;
517 
518 	dma_resv_iter_begin(&cursor, src, DMA_RESV_USAGE_BOOKKEEP);
519 	dma_resv_for_each_fence_unlocked(&cursor, f) {
520 
521 		if (dma_resv_iter_is_restarted(&cursor)) {
522 			dma_resv_list_free(list);
523 
524 			list = dma_resv_list_alloc(cursor.num_fences);
525 			if (!list) {
526 				dma_resv_iter_end(&cursor);
527 				return -ENOMEM;
528 			}
529 			list->num_fences = 0;
530 		}
531 
532 		dma_fence_get(f);
533 		dma_resv_list_set(list, list->num_fences++, f,
534 				  dma_resv_iter_usage(&cursor));
535 	}
536 	dma_resv_iter_end(&cursor);
537 
538 	list = rcu_replace_pointer(dst->fences, list, dma_resv_held(dst));
539 	dma_resv_list_free(list);
540 	return 0;
541 }
542 EXPORT_SYMBOL(dma_resv_copy_fences);
543 
544 /**
545  * dma_resv_get_fences - Get an object's fences
546  * fences without update side lock held
547  * @obj: the reservation object
548  * @usage: controls which fences to include, see enum dma_resv_usage.
549  * @num_fences: the number of fences returned
550  * @fences: the array of fence ptrs returned (array is krealloc'd to the
551  * required size, and must be freed by caller)
552  *
553  * Retrieve all fences from the reservation object.
554  * Returns either zero or -ENOMEM.
555  */
dma_resv_get_fences(struct dma_resv * obj,enum dma_resv_usage usage,unsigned int * num_fences,struct dma_fence *** fences)556 int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
557 			unsigned int *num_fences, struct dma_fence ***fences)
558 {
559 	struct dma_resv_iter cursor;
560 	struct dma_fence *fence;
561 
562 	*num_fences = 0;
563 	*fences = NULL;
564 
565 	dma_resv_iter_begin(&cursor, obj, usage);
566 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
567 
568 		if (dma_resv_iter_is_restarted(&cursor)) {
569 			unsigned int count;
570 
571 			while (*num_fences)
572 				dma_fence_put((*fences)[--(*num_fences)]);
573 
574 			count = cursor.num_fences + 1;
575 
576 			/* Eventually re-allocate the array */
577 			*fences = krealloc_array(*fences, count,
578 						 sizeof(void *),
579 						 GFP_KERNEL);
580 			if (count && !*fences) {
581 				dma_resv_iter_end(&cursor);
582 				return -ENOMEM;
583 			}
584 		}
585 
586 		(*fences)[(*num_fences)++] = dma_fence_get(fence);
587 	}
588 	dma_resv_iter_end(&cursor);
589 
590 	return 0;
591 }
592 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
593 
594 /**
595  * dma_resv_get_singleton - Get a single fence for all the fences
596  * @obj: the reservation object
597  * @usage: controls which fences to include, see enum dma_resv_usage.
598  * @fence: the resulting fence
599  *
600  * Get a single fence representing all the fences inside the resv object.
601  * Returns either 0 for success or -ENOMEM.
602  *
603  * Warning: This can't be used like this when adding the fence back to the resv
604  * object since that can lead to stack corruption when finalizing the
605  * dma_fence_array.
606  *
607  * Returns 0 on success and negative error values on failure.
608  */
dma_resv_get_singleton(struct dma_resv * obj,enum dma_resv_usage usage,struct dma_fence ** fence)609 int dma_resv_get_singleton(struct dma_resv *obj, enum dma_resv_usage usage,
610 			   struct dma_fence **fence)
611 {
612 	struct dma_fence_array *array;
613 	struct dma_fence **fences;
614 	unsigned count;
615 	int r;
616 
617 	r = dma_resv_get_fences(obj, usage, &count, &fences);
618         if (r)
619 		return r;
620 
621 	if (count == 0) {
622 		*fence = NULL;
623 		return 0;
624 	}
625 
626 	if (count == 1) {
627 		*fence = fences[0];
628 		kfree(fences);
629 		return 0;
630 	}
631 
632 	array = dma_fence_array_create(count, fences,
633 				       dma_fence_context_alloc(1),
634 				       1, false);
635 	if (!array) {
636 		while (count--)
637 			dma_fence_put(fences[count]);
638 		kfree(fences);
639 		return -ENOMEM;
640 	}
641 
642 	*fence = &array->base;
643 	return 0;
644 }
645 EXPORT_SYMBOL_GPL(dma_resv_get_singleton);
646 
647 /**
648  * dma_resv_wait_timeout - Wait on reservation's objects fences
649  * @obj: the reservation object
650  * @usage: controls which fences to include, see enum dma_resv_usage.
651  * @intr: if true, do interruptible wait
652  * @timeout: timeout value in jiffies or zero to return immediately
653  *
654  * Callers are not required to hold specific locks, but maybe hold
655  * dma_resv_lock() already
656  * RETURNS
657  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
658  * greater than zer on success.
659  */
dma_resv_wait_timeout(struct dma_resv * obj,enum dma_resv_usage usage,bool intr,unsigned long timeout)660 long dma_resv_wait_timeout(struct dma_resv *obj, enum dma_resv_usage usage,
661 			   bool intr, unsigned long timeout)
662 {
663 	long ret = timeout ? timeout : 1;
664 	struct dma_resv_iter cursor;
665 	struct dma_fence *fence;
666 
667 	dma_resv_iter_begin(&cursor, obj, usage);
668 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
669 
670 		ret = dma_fence_wait_timeout(fence, intr, ret);
671 		if (ret <= 0) {
672 			dma_resv_iter_end(&cursor);
673 			return ret;
674 		}
675 	}
676 	dma_resv_iter_end(&cursor);
677 
678 	return ret;
679 }
680 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
681 
682 
683 /**
684  * dma_resv_test_signaled - Test if a reservation object's fences have been
685  * signaled.
686  * @obj: the reservation object
687  * @usage: controls which fences to include, see enum dma_resv_usage.
688  *
689  * Callers are not required to hold specific locks, but maybe hold
690  * dma_resv_lock() already.
691  *
692  * RETURNS
693  *
694  * True if all fences signaled, else false.
695  */
dma_resv_test_signaled(struct dma_resv * obj,enum dma_resv_usage usage)696 bool dma_resv_test_signaled(struct dma_resv *obj, enum dma_resv_usage usage)
697 {
698 	struct dma_resv_iter cursor;
699 	struct dma_fence *fence;
700 
701 	dma_resv_iter_begin(&cursor, obj, usage);
702 	dma_resv_for_each_fence_unlocked(&cursor, fence) {
703 		dma_resv_iter_end(&cursor);
704 		return false;
705 	}
706 	dma_resv_iter_end(&cursor);
707 	return true;
708 }
709 EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
710 
711 /**
712  * dma_resv_describe - Dump description of the resv object into seq_file
713  * @obj: the reservation object
714  * @seq: the seq_file to dump the description into
715  *
716  * Dump a textual description of the fences inside an dma_resv object into the
717  * seq_file.
718  */
dma_resv_describe(struct dma_resv * obj,struct seq_file * seq)719 void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq)
720 {
721 	static const char *usage[] = { "kernel", "write", "read", "bookkeep" };
722 	struct dma_resv_iter cursor;
723 	struct dma_fence *fence;
724 
725 	dma_resv_for_each_fence(&cursor, obj, DMA_RESV_USAGE_READ, fence) {
726 		seq_printf(seq, "\t%s fence:",
727 			   usage[dma_resv_iter_usage(&cursor)]);
728 		dma_fence_describe(fence, seq);
729 	}
730 }
731 EXPORT_SYMBOL_GPL(dma_resv_describe);
732 
733 #if IS_ENABLED(CONFIG_LOCKDEP)
dma_resv_lockdep(void)734 static int __init dma_resv_lockdep(void)
735 {
736 	struct mm_struct *mm = mm_alloc();
737 	struct ww_acquire_ctx ctx;
738 	struct dma_resv obj;
739 	struct address_space mapping;
740 	int ret;
741 
742 	if (!mm)
743 		return -ENOMEM;
744 
745 	dma_resv_init(&obj);
746 	address_space_init_once(&mapping);
747 
748 	mmap_read_lock(mm);
749 	ww_acquire_init(&ctx, &reservation_ww_class);
750 	ret = dma_resv_lock(&obj, &ctx);
751 	if (ret == -EDEADLK)
752 		dma_resv_lock_slow(&obj, &ctx);
753 	fs_reclaim_acquire(GFP_KERNEL);
754 	/* for unmap_mapping_range on trylocked buffer objects in shrinkers */
755 	i_mmap_lock_write(&mapping);
756 	i_mmap_unlock_write(&mapping);
757 #ifdef CONFIG_MMU_NOTIFIER
758 	lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
759 	__dma_fence_might_wait();
760 	lock_map_release(&__mmu_notifier_invalidate_range_start_map);
761 #else
762 	__dma_fence_might_wait();
763 #endif
764 	fs_reclaim_release(GFP_KERNEL);
765 	ww_mutex_unlock(&obj.lock);
766 	ww_acquire_fini(&ctx);
767 	mmap_read_unlock(mm);
768 
769 	mmput(mm);
770 
771 	return 0;
772 }
773 subsys_initcall(dma_resv_lockdep);
774 #endif
775