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1/*
2 * Header file for reservations for dma-buf and ttm
3 *
4 * Copyright(C) 2011 Linaro Limited. All rights reserved.
5 * Copyright (C) 2012-2013 Canonical Ltd
6 * Copyright (C) 2012 Texas Instruments
7 *
8 * Authors:
9 * Rob Clark <robdclark@gmail.com>
10 * Maarten Lankhorst <maarten.lankhorst@canonical.com>
11 * Thomas Hellstrom <thellstrom-at-vmware-dot-com>
12 *
13 * Based on bo.c which bears the following copyright notice,
14 * but is dual licensed:
15 *
16 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
17 * All Rights Reserved.
18 *
19 * Permission is hereby granted, free of charge, to any person obtaining a
20 * copy of this software and associated documentation files (the
21 * "Software"), to deal in the Software without restriction, including
22 * without limitation the rights to use, copy, modify, merge, publish,
23 * distribute, sub license, and/or sell copies of the Software, and to
24 * permit persons to whom the Software is furnished to do so, subject to
25 * the following conditions:
26 *
27 * The above copyright notice and this permission notice (including the
28 * next paragraph) shall be included in all copies or substantial portions
29 * of the Software.
30 *
31 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
32 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
33 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
34 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
35 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
36 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
37 * USE OR OTHER DEALINGS IN THE SOFTWARE.
38 */
39#ifndef _LINUX_RESERVATION_H
40#define _LINUX_RESERVATION_H
41
42#include <linux/ww_mutex.h>
43#include <linux/dma-fence.h>
44#include <linux/slab.h>
45#include <linux/seqlock.h>
46#include <linux/rcupdate.h>
47
48extern struct ww_class reservation_ww_class;
49extern struct lock_class_key reservation_seqcount_class;
50extern const char reservation_seqcount_string[];
51
52/**
53 * struct reservation_object_list - a list of shared fences
54 * @rcu: for internal use
55 * @shared_count: table of shared fences
56 * @shared_max: for growing shared fence table
57 * @shared: shared fence table
58 */
59struct reservation_object_list {
60 struct rcu_head rcu;
61 u32 shared_count, shared_max;
62 struct dma_fence __rcu *shared[];
63};
64
65/**
66 * struct reservation_object - a reservation object manages fences for a buffer
67 * @lock: update side lock
68 * @seq: sequence count for managing RCU read-side synchronization
69 * @fence_excl: the exclusive fence, if there is one currently
70 * @fence: list of current shared fences
71 */
72struct reservation_object {
73 struct ww_mutex lock;
74 seqcount_t seq;
75
76 struct dma_fence __rcu *fence_excl;
77 struct reservation_object_list __rcu *fence;
78};
79
80#define reservation_object_held(obj) lockdep_is_held(&(obj)->lock.base)
81#define reservation_object_assert_held(obj) \
82 lockdep_assert_held(&(obj)->lock.base)
83
84/**
85 * reservation_object_init - initialize a reservation object
86 * @obj: the reservation object
87 */
88static inline void
89reservation_object_init(struct reservation_object *obj)
90{
91 ww_mutex_init(&obj->lock, &reservation_ww_class);
92
93 __seqcount_init(&obj->seq, reservation_seqcount_string, &reservation_seqcount_class);
94 RCU_INIT_POINTER(obj->fence, NULL);
95 RCU_INIT_POINTER(obj->fence_excl, NULL);
96}
97
98/**
99 * reservation_object_fini - destroys a reservation object
100 * @obj: the reservation object
101 */
102static inline void
103reservation_object_fini(struct reservation_object *obj)
104{
105 int i;
106 struct reservation_object_list *fobj;
107 struct dma_fence *excl;
108
109 /*
110 * This object should be dead and all references must have
111 * been released to it, so no need to be protected with rcu.
112 */
113 excl = rcu_dereference_protected(obj->fence_excl, 1);
114 if (excl)
115 dma_fence_put(excl);
116
117 fobj = rcu_dereference_protected(obj->fence, 1);
118 if (fobj) {
119 for (i = 0; i < fobj->shared_count; ++i)
120 dma_fence_put(rcu_dereference_protected(fobj->shared[i], 1));
121
122 kfree(fobj);
123 }
124
125 ww_mutex_destroy(&obj->lock);
126}
127
128/**
129 * reservation_object_get_list - get the reservation object's
130 * shared fence list, with update-side lock held
131 * @obj: the reservation object
132 *
133 * Returns the shared fence list. Does NOT take references to
134 * the fence. The obj->lock must be held.
135 */
136static inline struct reservation_object_list *
137reservation_object_get_list(struct reservation_object *obj)
138{
139 return rcu_dereference_protected(obj->fence,
140 reservation_object_held(obj));
141}
142
143/**
144 * reservation_object_lock - lock the reservation object
145 * @obj: the reservation object
146 * @ctx: the locking context
147 *
148 * Locks the reservation object for exclusive access and modification. Note,
149 * that the lock is only against other writers, readers will run concurrently
150 * with a writer under RCU. The seqlock is used to notify readers if they
151 * overlap with a writer.
152 *
153 * As the reservation object may be locked by multiple parties in an
154 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
155 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
156 * object may be locked by itself by passing NULL as @ctx.
157 */
158static inline int
159reservation_object_lock(struct reservation_object *obj,
160 struct ww_acquire_ctx *ctx)
161{
162 return ww_mutex_lock(&obj->lock, ctx);
163}
164
165/**
166 * reservation_object_lock_interruptible - lock the reservation object
167 * @obj: the reservation object
168 * @ctx: the locking context
169 *
170 * Locks the reservation object interruptible for exclusive access and
171 * modification. Note, that the lock is only against other writers, readers
172 * will run concurrently with a writer under RCU. The seqlock is used to
173 * notify readers if they overlap with a writer.
174 *
175 * As the reservation object may be locked by multiple parties in an
176 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
177 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
178 * object may be locked by itself by passing NULL as @ctx.
179 */
180static inline int
181reservation_object_lock_interruptible(struct reservation_object *obj,
182 struct ww_acquire_ctx *ctx)
183{
184 return ww_mutex_lock_interruptible(&obj->lock, ctx);
185}
186
187
188/**
189 * reservation_object_trylock - trylock the reservation object
190 * @obj: the reservation object
191 *
192 * Tries to lock the reservation object for exclusive access and modification.
193 * Note, that the lock is only against other writers, readers will run
194 * concurrently with a writer under RCU. The seqlock is used to notify readers
195 * if they overlap with a writer.
196 *
197 * Also note that since no context is provided, no deadlock protection is
198 * possible.
199 *
200 * Returns true if the lock was acquired, false otherwise.
201 */
202static inline bool __must_check
203reservation_object_trylock(struct reservation_object *obj)
204{
205 return ww_mutex_trylock(&obj->lock);
206}
207
208/**
209 * reservation_object_unlock - unlock the reservation object
210 * @obj: the reservation object
211 *
212 * Unlocks the reservation object following exclusive access.
213 */
214static inline void
215reservation_object_unlock(struct reservation_object *obj)
216{
217#ifdef CONFIG_DEBUG_MUTEXES
218 /* Test shared fence slot reservation */
219 if (rcu_access_pointer(obj->fence)) {
220 struct reservation_object_list *fence =
221 reservation_object_get_list(obj);
222
223 fence->shared_max = fence->shared_count;
224 }
225#endif
226 ww_mutex_unlock(&obj->lock);
227}
228
229/**
230 * reservation_object_get_excl - get the reservation object's
231 * exclusive fence, with update-side lock held
232 * @obj: the reservation object
233 *
234 * Returns the exclusive fence (if any). Does NOT take a
235 * reference. Writers must hold obj->lock, readers may only
236 * hold a RCU read side lock.
237 *
238 * RETURNS
239 * The exclusive fence or NULL
240 */
241static inline struct dma_fence *
242reservation_object_get_excl(struct reservation_object *obj)
243{
244 return rcu_dereference_protected(obj->fence_excl,
245 reservation_object_held(obj));
246}
247
248/**
249 * reservation_object_get_excl_rcu - get the reservation object's
250 * exclusive fence, without lock held.
251 * @obj: the reservation object
252 *
253 * If there is an exclusive fence, this atomically increments it's
254 * reference count and returns it.
255 *
256 * RETURNS
257 * The exclusive fence or NULL if none
258 */
259static inline struct dma_fence *
260reservation_object_get_excl_rcu(struct reservation_object *obj)
261{
262 struct dma_fence *fence;
263
264 if (!rcu_access_pointer(obj->fence_excl))
265 return NULL;
266
267 rcu_read_lock();
268 fence = dma_fence_get_rcu_safe(&obj->fence_excl);
269 rcu_read_unlock();
270
271 return fence;
272}
273
274int reservation_object_reserve_shared(struct reservation_object *obj,
275 unsigned int num_fences);
276void reservation_object_add_shared_fence(struct reservation_object *obj,
277 struct dma_fence *fence);
278
279void reservation_object_add_excl_fence(struct reservation_object *obj,
280 struct dma_fence *fence);
281
282int reservation_object_get_fences_rcu(struct reservation_object *obj,
283 struct dma_fence **pfence_excl,
284 unsigned *pshared_count,
285 struct dma_fence ***pshared);
286
287int reservation_object_copy_fences(struct reservation_object *dst,
288 struct reservation_object *src);
289
290long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
291 bool wait_all, bool intr,
292 unsigned long timeout);
293
294bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
295 bool test_all);
296
297#endif /* _LINUX_RESERVATION_H */