2 * Copyright (C) 2012-2014 Canonical Ltd (Maarten Lankhorst)
4 * Based on bo.c which bears the following copyright notice,
5 * but is dual licensed:
7 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
10 * Permission is hereby granted, free of charge, to any person obtaining a
11 * copy of this software and associated documentation files (the
12 * "Software"), to deal in the Software without restriction, including
13 * without limitation the rights to use, copy, modify, merge, publish,
14 * distribute, sub license, and/or sell copies of the Software, and to
15 * permit persons to whom the Software is furnished to do so, subject to
16 * the following conditions:
18 * The above copyright notice and this permission notice (including the
19 * next paragraph) shall be included in all copies or substantial portions
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
25 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
26 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
27 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
28 * USE OR OTHER DEALINGS IN THE SOFTWARE.
30 **************************************************************************/
32 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
35 #include <linux/reservation.h>
36 #include <linux/export.h>
39 * DOC: Reservation Object Overview
41 * The reservation object provides a mechanism to manage shared and
42 * exclusive fences associated with a buffer. A reservation object
43 * can have attached one exclusive fence (normally associated with
44 * write operations) or N shared fences (read operations). The RCU
45 * mechanism is used to protect read access to fences from locked
49 DEFINE_WD_CLASS(reservation_ww_class);
50 EXPORT_SYMBOL(reservation_ww_class);
52 struct lock_class_key reservation_seqcount_class;
53 EXPORT_SYMBOL(reservation_seqcount_class);
55 const char reservation_seqcount_string[] = "reservation_seqcount";
56 EXPORT_SYMBOL(reservation_seqcount_string);
59 * reservation_object_reserve_shared - Reserve space to add shared fences to
60 * a reservation_object.
61 * @obj: reservation object
62 * @num_fences: number of fences we want to add
64 * Should be called before reservation_object_add_shared_fence(). Must
65 * be called with obj->lock held.
68 * Zero for success, or -errno
70 int reservation_object_reserve_shared(struct reservation_object *obj,
71 unsigned int num_fences)
73 struct reservation_object_list *old, *new;
74 unsigned int i, j, k, max;
76 reservation_object_assert_held(obj);
78 old = reservation_object_get_list(obj);
80 if (old && old->shared_max) {
81 if ((old->shared_count + num_fences) <= old->shared_max)
84 max = max(old->shared_count + num_fences,
90 new = kmalloc(offsetof(typeof(*new), shared[max]), GFP_KERNEL);
95 * no need to bump fence refcounts, rcu_read access
96 * requires the use of kref_get_unless_zero, and the
97 * references from the old struct are carried over to
100 for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
101 struct dma_fence *fence;
103 fence = rcu_dereference_protected(old->shared[i],
104 reservation_object_held(obj));
105 if (dma_fence_is_signaled(fence))
106 RCU_INIT_POINTER(new->shared[--k], fence);
108 RCU_INIT_POINTER(new->shared[j++], fence);
110 new->shared_count = j;
111 new->shared_max = max;
114 write_seqcount_begin(&obj->seq);
116 * RCU_INIT_POINTER can be used here,
117 * seqcount provides the necessary barriers
119 RCU_INIT_POINTER(obj->fence, new);
120 write_seqcount_end(&obj->seq);
126 /* Drop the references to the signaled fences */
127 for (i = k; i < new->shared_max; ++i) {
128 struct dma_fence *fence;
130 fence = rcu_dereference_protected(new->shared[i],
131 reservation_object_held(obj));
132 dma_fence_put(fence);
138 EXPORT_SYMBOL(reservation_object_reserve_shared);
141 * reservation_object_add_shared_fence - Add a fence to a shared slot
142 * @obj: the reservation object
143 * @fence: the shared fence to add
145 * Add a fence to a shared slot, obj->lock must be held, and
146 * reservation_object_reserve_shared() has been called.
148 void reservation_object_add_shared_fence(struct reservation_object *obj,
149 struct dma_fence *fence)
151 struct reservation_object_list *fobj;
152 unsigned int i, count;
154 dma_fence_get(fence);
156 reservation_object_assert_held(obj);
158 fobj = reservation_object_get_list(obj);
159 count = fobj->shared_count;
162 write_seqcount_begin(&obj->seq);
164 for (i = 0; i < count; ++i) {
165 struct dma_fence *old_fence;
167 old_fence = rcu_dereference_protected(fobj->shared[i],
168 reservation_object_held(obj));
169 if (old_fence->context == fence->context ||
170 dma_fence_is_signaled(old_fence)) {
171 dma_fence_put(old_fence);
176 BUG_ON(fobj->shared_count >= fobj->shared_max);
180 RCU_INIT_POINTER(fobj->shared[i], fence);
181 /* pointer update must be visible before we extend the shared_count */
182 smp_store_mb(fobj->shared_count, count);
184 write_seqcount_end(&obj->seq);
187 EXPORT_SYMBOL(reservation_object_add_shared_fence);
190 * reservation_object_add_excl_fence - Add an exclusive fence.
191 * @obj: the reservation object
192 * @fence: the shared fence to add
194 * Add a fence to the exclusive slot. The obj->lock must be held.
196 void reservation_object_add_excl_fence(struct reservation_object *obj,
197 struct dma_fence *fence)
199 struct dma_fence *old_fence = reservation_object_get_excl(obj);
200 struct reservation_object_list *old;
203 reservation_object_assert_held(obj);
205 old = reservation_object_get_list(obj);
207 i = old->shared_count;
210 dma_fence_get(fence);
213 write_seqcount_begin(&obj->seq);
214 /* write_seqcount_begin provides the necessary memory barrier */
215 RCU_INIT_POINTER(obj->fence_excl, fence);
217 old->shared_count = 0;
218 write_seqcount_end(&obj->seq);
221 /* inplace update, no shared fences */
223 dma_fence_put(rcu_dereference_protected(old->shared[i],
224 reservation_object_held(obj)));
226 dma_fence_put(old_fence);
228 EXPORT_SYMBOL(reservation_object_add_excl_fence);
231 * reservation_object_copy_fences - Copy all fences from src to dst.
232 * @dst: the destination reservation object
233 * @src: the source reservation object
235 * Copy all fences from src to dst. dst-lock must be held.
237 int reservation_object_copy_fences(struct reservation_object *dst,
238 struct reservation_object *src)
240 struct reservation_object_list *src_list, *dst_list;
241 struct dma_fence *old, *new;
245 reservation_object_assert_held(dst);
248 src_list = rcu_dereference(src->fence);
252 unsigned shared_count = src_list->shared_count;
254 size = offsetof(typeof(*src_list), shared[shared_count]);
257 dst_list = kmalloc(size, GFP_KERNEL);
262 src_list = rcu_dereference(src->fence);
263 if (!src_list || src_list->shared_count > shared_count) {
268 dst_list->shared_count = 0;
269 dst_list->shared_max = shared_count;
270 for (i = 0; i < src_list->shared_count; ++i) {
271 struct dma_fence *fence;
273 fence = rcu_dereference(src_list->shared[i]);
274 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
278 if (!dma_fence_get_rcu(fence)) {
280 src_list = rcu_dereference(src->fence);
284 if (dma_fence_is_signaled(fence)) {
285 dma_fence_put(fence);
289 rcu_assign_pointer(dst_list->shared[dst_list->shared_count++], fence);
295 new = dma_fence_get_rcu_safe(&src->fence_excl);
298 src_list = reservation_object_get_list(dst);
299 old = reservation_object_get_excl(dst);
302 write_seqcount_begin(&dst->seq);
303 /* write_seqcount_begin provides the necessary memory barrier */
304 RCU_INIT_POINTER(dst->fence_excl, new);
305 RCU_INIT_POINTER(dst->fence, dst_list);
306 write_seqcount_end(&dst->seq);
310 kfree_rcu(src_list, rcu);
315 EXPORT_SYMBOL(reservation_object_copy_fences);
318 * reservation_object_get_fences_rcu - Get an object's shared and exclusive
319 * fences without update side lock held
320 * @obj: the reservation object
321 * @pfence_excl: the returned exclusive fence (or NULL)
322 * @pshared_count: the number of shared fences returned
323 * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
324 * the required size, and must be freed by caller)
326 * Retrieve all fences from the reservation object. If the pointer for the
327 * exclusive fence is not specified the fence is put into the array of the
328 * shared fences as well. Returns either zero or -ENOMEM.
330 int reservation_object_get_fences_rcu(struct reservation_object *obj,
331 struct dma_fence **pfence_excl,
332 unsigned *pshared_count,
333 struct dma_fence ***pshared)
335 struct dma_fence **shared = NULL;
336 struct dma_fence *fence_excl;
337 unsigned int shared_count;
341 struct reservation_object_list *fobj;
345 shared_count = i = 0;
348 seq = read_seqcount_begin(&obj->seq);
350 fence_excl = rcu_dereference(obj->fence_excl);
351 if (fence_excl && !dma_fence_get_rcu(fence_excl))
354 fobj = rcu_dereference(obj->fence);
356 sz += sizeof(*shared) * fobj->shared_max;
358 if (!pfence_excl && fence_excl)
359 sz += sizeof(*shared);
362 struct dma_fence **nshared;
364 nshared = krealloc(shared, sz,
365 GFP_NOWAIT | __GFP_NOWARN);
368 nshared = krealloc(shared, sz, GFP_KERNEL);
378 shared_count = fobj ? fobj->shared_count : 0;
379 for (i = 0; i < shared_count; ++i) {
380 shared[i] = rcu_dereference(fobj->shared[i]);
381 if (!dma_fence_get_rcu(shared[i]))
385 if (!pfence_excl && fence_excl) {
386 shared[i] = fence_excl;
393 if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
395 dma_fence_put(shared[i]);
396 dma_fence_put(fence_excl);
410 *pshared_count = shared_count;
413 *pfence_excl = fence_excl;
417 EXPORT_SYMBOL_GPL(reservation_object_get_fences_rcu);
420 * reservation_object_wait_timeout_rcu - Wait on reservation's objects
421 * shared and/or exclusive fences.
422 * @obj: the reservation object
423 * @wait_all: if true, wait on all fences, else wait on just exclusive fence
424 * @intr: if true, do interruptible wait
425 * @timeout: timeout value in jiffies or zero to return immediately
428 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
429 * greater than zer on success.
431 long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
432 bool wait_all, bool intr,
433 unsigned long timeout)
435 struct dma_fence *fence;
436 unsigned seq, shared_count;
437 long ret = timeout ? timeout : 1;
442 seq = read_seqcount_begin(&obj->seq);
446 fence = rcu_dereference(obj->fence_excl);
447 if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
448 if (!dma_fence_get_rcu(fence))
451 if (dma_fence_is_signaled(fence)) {
452 dma_fence_put(fence);
461 struct reservation_object_list *fobj =
462 rcu_dereference(obj->fence);
465 shared_count = fobj->shared_count;
467 for (i = 0; !fence && i < shared_count; ++i) {
468 struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
470 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
474 if (!dma_fence_get_rcu(lfence))
477 if (dma_fence_is_signaled(lfence)) {
478 dma_fence_put(lfence);
489 if (read_seqcount_retry(&obj->seq, seq)) {
490 dma_fence_put(fence);
494 ret = dma_fence_wait_timeout(fence, intr, ret);
495 dma_fence_put(fence);
496 if (ret > 0 && wait_all && (i + 1 < shared_count))
505 EXPORT_SYMBOL_GPL(reservation_object_wait_timeout_rcu);
509 reservation_object_test_signaled_single(struct dma_fence *passed_fence)
511 struct dma_fence *fence, *lfence = passed_fence;
514 if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
515 fence = dma_fence_get_rcu(lfence);
519 ret = !!dma_fence_is_signaled(fence);
520 dma_fence_put(fence);
526 * reservation_object_test_signaled_rcu - Test if a reservation object's
527 * fences have been signaled.
528 * @obj: the reservation object
529 * @test_all: if true, test all fences, otherwise only test the exclusive
533 * true if all fences signaled, else false
535 bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
538 unsigned seq, shared_count;
545 seq = read_seqcount_begin(&obj->seq);
550 struct reservation_object_list *fobj =
551 rcu_dereference(obj->fence);
554 shared_count = fobj->shared_count;
556 for (i = 0; i < shared_count; ++i) {
557 struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
559 ret = reservation_object_test_signaled_single(fence);
566 if (read_seqcount_retry(&obj->seq, seq))
571 struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl);
574 ret = reservation_object_test_signaled_single(
579 if (read_seqcount_retry(&obj->seq, seq))
587 EXPORT_SYMBOL_GPL(reservation_object_test_signaled_rcu);