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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:
0ba6b8fb 9 * Rob Clark <robdclark@gmail.com>
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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
1b375dc3 42#include <linux/ww_mutex.h>
f54d1867 43#include <linux/dma-fence.h>
0ba6b8fb 44#include <linux/slab.h>
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45#include <linux/seqlock.h>
46#include <linux/rcupdate.h>
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47
48extern struct ww_class reservation_ww_class;
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49extern struct lock_class_key reservation_seqcount_class;
50extern const char reservation_seqcount_string[];
786d7257 51
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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 */
04a5faa8 59struct reservation_object_list {
3c3b177a 60 struct rcu_head rcu;
04a5faa8 61 u32 shared_count, shared_max;
f54d1867 62 struct dma_fence __rcu *shared[];
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63};
64
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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 * @staged: staged copy of shared fences for RCU updates
72 */
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73struct reservation_object {
74 struct ww_mutex lock;
3c3b177a 75 seqcount_t seq;
0ba6b8fb 76
f54d1867 77 struct dma_fence __rcu *fence_excl;
3c3b177a 78 struct reservation_object_list __rcu *fence;
04a5faa8 79 struct reservation_object_list *staged;
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80};
81
3c3b177a 82#define reservation_object_held(obj) lockdep_is_held(&(obj)->lock.base)
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83#define reservation_object_assert_held(obj) \
84 lockdep_assert_held(&(obj)->lock.base)
85
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86/**
87 * reservation_object_init - initialize a reservation object
88 * @obj: the reservation object
89 */
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90static inline void
91reservation_object_init(struct reservation_object *obj)
92{
93 ww_mutex_init(&obj->lock, &reservation_ww_class);
0ba6b8fb 94
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95 __seqcount_init(&obj->seq, reservation_seqcount_string, &reservation_seqcount_class);
96 RCU_INIT_POINTER(obj->fence, NULL);
97 RCU_INIT_POINTER(obj->fence_excl, NULL);
04a5faa8 98 obj->staged = NULL;
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99}
100
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101/**
102 * reservation_object_fini - destroys a reservation object
103 * @obj: the reservation object
104 */
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105static inline void
106reservation_object_fini(struct reservation_object *obj)
107{
0ba6b8fb 108 int i;
04a5faa8 109 struct reservation_object_list *fobj;
f54d1867 110 struct dma_fence *excl;
0ba6b8fb 111
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112 /*
113 * This object should be dead and all references must have
3c3b177a 114 * been released to it, so no need to be protected with rcu.
04a5faa8 115 */
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116 excl = rcu_dereference_protected(obj->fence_excl, 1);
117 if (excl)
f54d1867 118 dma_fence_put(excl);
04a5faa8 119
3c3b177a 120 fobj = rcu_dereference_protected(obj->fence, 1);
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121 if (fobj) {
122 for (i = 0; i < fobj->shared_count; ++i)
f54d1867 123 dma_fence_put(rcu_dereference_protected(fobj->shared[i], 1));
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124
125 kfree(fobj);
126 }
127 kfree(obj->staged);
0ba6b8fb 128
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129 ww_mutex_destroy(&obj->lock);
130}
131
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132/**
133 * reservation_object_get_list - get the reservation object's
134 * shared fence list, with update-side lock held
135 * @obj: the reservation object
136 *
137 * Returns the shared fence list. Does NOT take references to
138 * the fence. The obj->lock must be held.
139 */
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140static inline struct reservation_object_list *
141reservation_object_get_list(struct reservation_object *obj)
142{
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143 return rcu_dereference_protected(obj->fence,
144 reservation_object_held(obj));
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145}
146
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147/**
148 * reservation_object_lock - lock the reservation object
149 * @obj: the reservation object
150 * @ctx: the locking context
151 *
152 * Locks the reservation object for exclusive access and modification. Note,
153 * that the lock is only against other writers, readers will run concurrently
154 * with a writer under RCU. The seqlock is used to notify readers if they
155 * overlap with a writer.
156 *
157 * As the reservation object may be locked by multiple parties in an
158 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
159 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
160 * object may be locked by itself by passing NULL as @ctx.
161 */
162static inline int
163reservation_object_lock(struct reservation_object *obj,
164 struct ww_acquire_ctx *ctx)
165{
166 return ww_mutex_lock(&obj->lock, ctx);
167}
168
169/**
170 * reservation_object_unlock - unlock the reservation object
171 * @obj: the reservation object
172 *
173 * Unlocks the reservation object following exclusive access.
174 */
175static inline void
176reservation_object_unlock(struct reservation_object *obj)
177{
178 ww_mutex_unlock(&obj->lock);
179}
180
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181/**
182 * reservation_object_get_excl - get the reservation object's
183 * exclusive fence, with update-side lock held
184 * @obj: the reservation object
185 *
186 * Returns the exclusive fence (if any). Does NOT take a
187 * reference. The obj->lock must be held.
188 *
189 * RETURNS
190 * The exclusive fence or NULL
191 */
f54d1867 192static inline struct dma_fence *
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193reservation_object_get_excl(struct reservation_object *obj)
194{
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195 return rcu_dereference_protected(obj->fence_excl,
196 reservation_object_held(obj));
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197}
198
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199/**
200 * reservation_object_get_excl_rcu - get the reservation object's
201 * exclusive fence, without lock held.
202 * @obj: the reservation object
203 *
204 * If there is an exclusive fence, this atomically increments it's
205 * reference count and returns it.
206 *
207 * RETURNS
208 * The exclusive fence or NULL if none
209 */
f54d1867 210static inline struct dma_fence *
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211reservation_object_get_excl_rcu(struct reservation_object *obj)
212{
f54d1867 213 struct dma_fence *fence;
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214
215 if (!rcu_access_pointer(obj->fence_excl))
216 return NULL;
217
824815c4 218 rcu_read_lock();
6bfec6d9 219 fence = dma_fence_get_rcu_safe(&obj->fence_excl);
824815c4 220 rcu_read_unlock();
6bfec6d9 221
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222 return fence;
223}
224
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225int reservation_object_reserve_shared(struct reservation_object *obj);
226void reservation_object_add_shared_fence(struct reservation_object *obj,
f54d1867 227 struct dma_fence *fence);
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228
229void reservation_object_add_excl_fence(struct reservation_object *obj,
f54d1867 230 struct dma_fence *fence);
04a5faa8 231
3c3b177a 232int reservation_object_get_fences_rcu(struct reservation_object *obj,
f54d1867 233 struct dma_fence **pfence_excl,
3c3b177a 234 unsigned *pshared_count,
f54d1867 235 struct dma_fence ***pshared);
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236
237long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
238 bool wait_all, bool intr,
239 unsigned long timeout);
240
241bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
242 bool test_all);
243
786d7257 244#endif /* _LINUX_RESERVATION_H */