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_WW_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 a shared
60 * fence to a reservation_object.
61 * @obj: reservation object
63 * Should be called before reservation_object_add_shared_fence(). Must
64 * be called with obj->lock held.
67 * Zero for success, or -errno
69 int reservation_object_reserve_shared(struct reservation_object *obj)
71 struct reservation_object_list *fobj, *old;
74 old = reservation_object_get_list(obj);
76 if (old && old->shared_max) {
77 if (old->shared_count < old->shared_max) {
78 /* perform an in-place update */
83 max = old->shared_max * 2;
88 * resize obj->staged or allocate if it doesn't exist,
89 * noop if already correct size
91 fobj = krealloc(obj->staged, offsetof(typeof(*fobj), shared[max]),
97 fobj->shared_max = max;
100 EXPORT_SYMBOL(reservation_object_reserve_shared);
103 reservation_object_add_shared_inplace(struct reservation_object *obj,
104 struct reservation_object_list *fobj,
105 struct dma_fence *fence)
109 dma_fence_get(fence);
112 write_seqcount_begin(&obj->seq);
114 for (i = 0; i < fobj->shared_count; ++i) {
115 struct dma_fence *old_fence;
117 old_fence = rcu_dereference_protected(fobj->shared[i],
118 reservation_object_held(obj));
120 if (old_fence->context == fence->context) {
121 /* memory barrier is added by write_seqcount_begin */
122 RCU_INIT_POINTER(fobj->shared[i], fence);
123 write_seqcount_end(&obj->seq);
126 dma_fence_put(old_fence);
132 * memory barrier is added by write_seqcount_begin,
133 * fobj->shared_count is protected by this lock too
135 RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence);
136 fobj->shared_count++;
138 write_seqcount_end(&obj->seq);
143 reservation_object_add_shared_replace(struct reservation_object *obj,
144 struct reservation_object_list *old,
145 struct reservation_object_list *fobj,
146 struct dma_fence *fence)
149 struct dma_fence *old_fence = NULL;
151 dma_fence_get(fence);
154 RCU_INIT_POINTER(fobj->shared[0], fence);
155 fobj->shared_count = 1;
160 * no need to bump fence refcounts, rcu_read access
161 * requires the use of kref_get_unless_zero, and the
162 * references from the old struct are carried over to
165 fobj->shared_count = old->shared_count;
167 for (i = 0; i < old->shared_count; ++i) {
168 struct dma_fence *check;
170 check = rcu_dereference_protected(old->shared[i],
171 reservation_object_held(obj));
173 if (!old_fence && check->context == fence->context) {
175 RCU_INIT_POINTER(fobj->shared[i], fence);
177 RCU_INIT_POINTER(fobj->shared[i], check);
180 RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence);
181 fobj->shared_count++;
186 write_seqcount_begin(&obj->seq);
188 * RCU_INIT_POINTER can be used here,
189 * seqcount provides the necessary barriers
191 RCU_INIT_POINTER(obj->fence, fobj);
192 write_seqcount_end(&obj->seq);
198 dma_fence_put(old_fence);
202 * reservation_object_add_shared_fence - Add a fence to a shared slot
203 * @obj: the reservation object
204 * @fence: the shared fence to add
206 * Add a fence to a shared slot, obj->lock must be held, and
207 * reservation_object_reserve_shared() has been called.
209 void reservation_object_add_shared_fence(struct reservation_object *obj,
210 struct dma_fence *fence)
212 struct reservation_object_list *old, *fobj = obj->staged;
214 old = reservation_object_get_list(obj);
218 BUG_ON(old->shared_count >= old->shared_max);
219 reservation_object_add_shared_inplace(obj, old, fence);
221 reservation_object_add_shared_replace(obj, old, fobj, fence);
223 EXPORT_SYMBOL(reservation_object_add_shared_fence);
226 * reservation_object_add_excl_fence - Add an exclusive fence.
227 * @obj: the reservation object
228 * @fence: the shared fence to add
230 * Add a fence to the exclusive slot. The obj->lock must be held.
232 void reservation_object_add_excl_fence(struct reservation_object *obj,
233 struct dma_fence *fence)
235 struct dma_fence *old_fence = reservation_object_get_excl(obj);
236 struct reservation_object_list *old;
239 old = reservation_object_get_list(obj);
241 i = old->shared_count;
244 dma_fence_get(fence);
247 write_seqcount_begin(&obj->seq);
248 /* write_seqcount_begin provides the necessary memory barrier */
249 RCU_INIT_POINTER(obj->fence_excl, fence);
251 old->shared_count = 0;
252 write_seqcount_end(&obj->seq);
255 /* inplace update, no shared fences */
257 dma_fence_put(rcu_dereference_protected(old->shared[i],
258 reservation_object_held(obj)));
260 dma_fence_put(old_fence);
262 EXPORT_SYMBOL(reservation_object_add_excl_fence);
265 * reservation_object_copy_fences - Copy all fences from src to dst.
266 * @dst: the destination reservation object
267 * @src: the source reservation object
269 * Copy all fences from src to dst. Both src->lock as well as dst-lock must be
272 int reservation_object_copy_fences(struct reservation_object *dst,
273 struct reservation_object *src)
275 struct reservation_object_list *src_list, *dst_list;
276 struct dma_fence *old, *new;
280 src_list = reservation_object_get_list(src);
283 size = offsetof(typeof(*src_list),
284 shared[src_list->shared_count]);
285 dst_list = kmalloc(size, GFP_KERNEL);
289 dst_list->shared_count = src_list->shared_count;
290 dst_list->shared_max = src_list->shared_count;
291 for (i = 0; i < src_list->shared_count; ++i)
292 dst_list->shared[i] =
293 dma_fence_get(src_list->shared[i]);
301 src_list = reservation_object_get_list(dst);
303 old = reservation_object_get_excl(dst);
304 new = reservation_object_get_excl(src);
309 write_seqcount_begin(&dst->seq);
310 /* write_seqcount_begin provides the necessary memory barrier */
311 RCU_INIT_POINTER(dst->fence_excl, new);
312 RCU_INIT_POINTER(dst->fence, dst_list);
313 write_seqcount_end(&dst->seq);
317 kfree_rcu(src_list, rcu);
322 EXPORT_SYMBOL(reservation_object_copy_fences);
325 * reservation_object_get_fences_rcu - Get an object's shared and exclusive
326 * fences without update side lock held
327 * @obj: the reservation object
328 * @pfence_excl: the returned exclusive fence (or NULL)
329 * @pshared_count: the number of shared fences returned
330 * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
331 * the required size, and must be freed by caller)
336 int reservation_object_get_fences_rcu(struct reservation_object *obj,
337 struct dma_fence **pfence_excl,
338 unsigned *pshared_count,
339 struct dma_fence ***pshared)
341 struct dma_fence **shared = NULL;
342 struct dma_fence *fence_excl;
343 unsigned int shared_count;
347 struct reservation_object_list *fobj;
351 shared_count = i = 0;
354 seq = read_seqcount_begin(&obj->seq);
356 fence_excl = rcu_dereference(obj->fence_excl);
357 if (fence_excl && !dma_fence_get_rcu(fence_excl))
360 fobj = rcu_dereference(obj->fence);
362 struct dma_fence **nshared;
363 size_t sz = sizeof(*shared) * fobj->shared_max;
365 nshared = krealloc(shared, sz,
366 GFP_NOWAIT | __GFP_NOWARN);
369 nshared = krealloc(shared, sz, GFP_KERNEL);
379 shared_count = fobj->shared_count;
381 for (i = 0; i < shared_count; ++i) {
382 shared[i] = rcu_dereference(fobj->shared[i]);
383 if (!dma_fence_get_rcu(shared[i]))
388 if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
390 dma_fence_put(shared[i]);
391 dma_fence_put(fence_excl);
405 *pshared_count = shared_count;
407 *pfence_excl = fence_excl;
411 EXPORT_SYMBOL_GPL(reservation_object_get_fences_rcu);
414 * reservation_object_wait_timeout_rcu - Wait on reservation's objects
415 * shared and/or exclusive fences.
416 * @obj: the reservation object
417 * @wait_all: if true, wait on all fences, else wait on just exclusive fence
418 * @intr: if true, do interruptible wait
419 * @timeout: timeout value in jiffies or zero to return immediately
422 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
423 * greater than zer on success.
425 long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
426 bool wait_all, bool intr,
427 unsigned long timeout)
429 struct dma_fence *fence;
430 unsigned seq, shared_count, i = 0;
431 long ret = timeout ? timeout : 1;
435 seq = read_seqcount_begin(&obj->seq);
438 fence = rcu_dereference(obj->fence_excl);
439 if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
440 if (!dma_fence_get_rcu(fence))
443 if (dma_fence_is_signaled(fence)) {
444 dma_fence_put(fence);
452 if (!fence && wait_all) {
453 struct reservation_object_list *fobj =
454 rcu_dereference(obj->fence);
457 shared_count = fobj->shared_count;
459 for (i = 0; i < shared_count; ++i) {
460 struct dma_fence *lfence = rcu_dereference(fobj->shared[i]);
462 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
466 if (!dma_fence_get_rcu(lfence))
469 if (dma_fence_is_signaled(lfence)) {
470 dma_fence_put(lfence);
481 if (read_seqcount_retry(&obj->seq, seq)) {
482 dma_fence_put(fence);
486 ret = dma_fence_wait_timeout(fence, intr, ret);
487 dma_fence_put(fence);
488 if (ret > 0 && wait_all && (i + 1 < shared_count))
497 EXPORT_SYMBOL_GPL(reservation_object_wait_timeout_rcu);
501 reservation_object_test_signaled_single(struct dma_fence *passed_fence)
503 struct dma_fence *fence, *lfence = passed_fence;
506 if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
507 fence = dma_fence_get_rcu(lfence);
511 ret = !!dma_fence_is_signaled(fence);
512 dma_fence_put(fence);
518 * reservation_object_test_signaled_rcu - Test if a reservation object's
519 * fences have been signaled.
520 * @obj: the reservation object
521 * @test_all: if true, test all fences, otherwise only test the exclusive
525 * true if all fences signaled, else false
527 bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
530 unsigned seq, shared_count;
537 seq = read_seqcount_begin(&obj->seq);
542 struct reservation_object_list *fobj =
543 rcu_dereference(obj->fence);
546 shared_count = fobj->shared_count;
548 for (i = 0; i < shared_count; ++i) {
549 struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
551 ret = reservation_object_test_signaled_single(fence);
558 if (read_seqcount_retry(&obj->seq, seq))
563 struct dma_fence *fence_excl = rcu_dereference(obj->fence_excl);
566 ret = reservation_object_test_signaled_single(
571 if (read_seqcount_retry(&obj->seq, seq))
579 EXPORT_SYMBOL_GPL(reservation_object_test_signaled_rcu);