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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 : :
48 : : extern struct ww_class reservation_ww_class;
49 : : extern struct lock_class_key reservation_seqcount_class;
50 : : extern const char reservation_seqcount_string[];
51 : :
52 : : /**
53 : : * struct dma_resv_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 : : */
59 : : struct dma_resv_list {
60 : : struct rcu_head rcu;
61 : : u32 shared_count, shared_max;
62 : : struct dma_fence __rcu *shared[];
63 : : };
64 : :
65 : : /**
66 : : * struct dma_resv - 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 : : */
72 : : struct dma_resv {
73 : : struct ww_mutex lock;
74 : : seqcount_t seq;
75 : :
76 : : struct dma_fence __rcu *fence_excl;
77 : : struct dma_resv_list __rcu *fence;
78 : : };
79 : :
80 : : #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
81 : : #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
82 : :
83 : : /**
84 : : * dma_resv_get_list - get the reservation object's
85 : : * shared fence list, with update-side lock held
86 : : * @obj: the reservation object
87 : : *
88 : : * Returns the shared fence list. Does NOT take references to
89 : : * the fence. The obj->lock must be held.
90 : : */
91 : 0 : static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj)
92 : : {
93 [ # # # # ]: 0 : return rcu_dereference_protected(obj->fence,
94 : : dma_resv_held(obj));
95 : : }
96 : :
97 : : /**
98 : : * dma_resv_lock - lock the reservation object
99 : : * @obj: the reservation object
100 : : * @ctx: the locking context
101 : : *
102 : : * Locks the reservation object for exclusive access and modification. Note,
103 : : * that the lock is only against other writers, readers will run concurrently
104 : : * with a writer under RCU. The seqlock is used to notify readers if they
105 : : * overlap with a writer.
106 : : *
107 : : * As the reservation object may be locked by multiple parties in an
108 : : * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
109 : : * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
110 : : * object may be locked by itself by passing NULL as @ctx.
111 : : */
112 : 0 : static inline int dma_resv_lock(struct dma_resv *obj,
113 : : struct ww_acquire_ctx *ctx)
114 : : {
115 : 0 : return ww_mutex_lock(&obj->lock, ctx);
116 : : }
117 : :
118 : : /**
119 : : * dma_resv_lock_interruptible - lock the reservation object
120 : : * @obj: the reservation object
121 : : * @ctx: the locking context
122 : : *
123 : : * Locks the reservation object interruptible for exclusive access and
124 : : * modification. Note, that the lock is only against other writers, readers
125 : : * will run concurrently with a writer under RCU. The seqlock is used to
126 : : * notify readers if they overlap with a writer.
127 : : *
128 : : * As the reservation object may be locked by multiple parties in an
129 : : * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
130 : : * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
131 : : * object may be locked by itself by passing NULL as @ctx.
132 : : */
133 : 0 : static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
134 : : struct ww_acquire_ctx *ctx)
135 : : {
136 : 0 : return ww_mutex_lock_interruptible(&obj->lock, ctx);
137 : : }
138 : :
139 : : /**
140 : : * dma_resv_lock_slow - slowpath lock the reservation object
141 : : * @obj: the reservation object
142 : : * @ctx: the locking context
143 : : *
144 : : * Acquires the reservation object after a die case. This function
145 : : * will sleep until the lock becomes available. See dma_resv_lock() as
146 : : * well.
147 : : */
148 : : static inline void dma_resv_lock_slow(struct dma_resv *obj,
149 : : struct ww_acquire_ctx *ctx)
150 : : {
151 : : ww_mutex_lock_slow(&obj->lock, ctx);
152 : : }
153 : :
154 : : /**
155 : : * dma_resv_lock_slow_interruptible - slowpath lock the reservation
156 : : * object, interruptible
157 : : * @obj: the reservation object
158 : : * @ctx: the locking context
159 : : *
160 : : * Acquires the reservation object interruptible after a die case. This function
161 : : * will sleep until the lock becomes available. See
162 : : * dma_resv_lock_interruptible() as well.
163 : : */
164 : 0 : static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
165 : : struct ww_acquire_ctx *ctx)
166 : : {
167 : 0 : return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
168 : : }
169 : :
170 : : /**
171 : : * dma_resv_trylock - trylock the reservation object
172 : : * @obj: the reservation object
173 : : *
174 : : * Tries to lock the reservation object for exclusive access and modification.
175 : : * Note, that the lock is only against other writers, readers will run
176 : : * concurrently with a writer under RCU. The seqlock is used to notify readers
177 : : * if they overlap with a writer.
178 : : *
179 : : * Also note that since no context is provided, no deadlock protection is
180 : : * possible.
181 : : *
182 : : * Returns true if the lock was acquired, false otherwise.
183 : : */
184 : 0 : static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
185 : : {
186 : 0 : return ww_mutex_trylock(&obj->lock);
187 : : }
188 : :
189 : : /**
190 : : * dma_resv_is_locked - is the reservation object locked
191 : : * @obj: the reservation object
192 : : *
193 : : * Returns true if the mutex is locked, false if unlocked.
194 : : */
195 : : static inline bool dma_resv_is_locked(struct dma_resv *obj)
196 : : {
197 : : return ww_mutex_is_locked(&obj->lock);
198 : : }
199 : :
200 : : /**
201 : : * dma_resv_locking_ctx - returns the context used to lock the object
202 : : * @obj: the reservation object
203 : : *
204 : : * Returns the context used to lock a reservation object or NULL if no context
205 : : * was used or the object is not locked at all.
206 : : */
207 : : static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
208 : : {
209 : : return READ_ONCE(obj->lock.ctx);
210 : : }
211 : :
212 : : /**
213 : : * dma_resv_unlock - unlock the reservation object
214 : : * @obj: the reservation object
215 : : *
216 : : * Unlocks the reservation object following exclusive access.
217 : : */
218 : 0 : static inline void dma_resv_unlock(struct dma_resv *obj)
219 : : {
220 : : #ifdef CONFIG_DEBUG_MUTEXES
221 : : /* Test shared fence slot reservation */
222 : : if (rcu_access_pointer(obj->fence)) {
223 : : struct dma_resv_list *fence = dma_resv_get_list(obj);
224 : :
225 : : fence->shared_max = fence->shared_count;
226 : : }
227 : : #endif
228 : 0 : ww_mutex_unlock(&obj->lock);
229 : 0 : }
230 : :
231 : : /**
232 : : * dma_resv_get_excl - get the reservation object's
233 : : * exclusive fence, with update-side lock held
234 : : * @obj: the reservation object
235 : : *
236 : : * Returns the exclusive fence (if any). Does NOT take a
237 : : * reference. Writers must hold obj->lock, readers may only
238 : : * hold a RCU read side lock.
239 : : *
240 : : * RETURNS
241 : : * The exclusive fence or NULL
242 : : */
243 : : static inline struct dma_fence *
244 : 0 : dma_resv_get_excl(struct dma_resv *obj)
245 : : {
246 [ # # ]: 0 : return rcu_dereference_protected(obj->fence_excl,
247 : : dma_resv_held(obj));
248 : : }
249 : :
250 : : /**
251 : : * dma_resv_get_excl_rcu - get the reservation object's
252 : : * exclusive fence, without lock held.
253 : : * @obj: the reservation object
254 : : *
255 : : * If there is an exclusive fence, this atomically increments it's
256 : : * reference count and returns it.
257 : : *
258 : : * RETURNS
259 : : * The exclusive fence or NULL if none
260 : : */
261 : : static inline struct dma_fence *
262 : 0 : dma_resv_get_excl_rcu(struct dma_resv *obj)
263 : : {
264 : 0 : struct dma_fence *fence;
265 : :
266 [ # # # # ]: 0 : if (!rcu_access_pointer(obj->fence_excl))
267 : : return NULL;
268 : :
269 : 0 : rcu_read_lock();
270 : 0 : fence = dma_fence_get_rcu_safe(&obj->fence_excl);
271 : 0 : rcu_read_unlock();
272 : :
273 [ # # ]: 0 : return fence;
274 : : }
275 : :
276 : : void dma_resv_init(struct dma_resv *obj);
277 : : void dma_resv_fini(struct dma_resv *obj);
278 : : int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
279 : : void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
280 : :
281 : : void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
282 : :
283 : : int dma_resv_get_fences_rcu(struct dma_resv *obj,
284 : : struct dma_fence **pfence_excl,
285 : : unsigned *pshared_count,
286 : : struct dma_fence ***pshared);
287 : :
288 : : int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
289 : :
290 : : long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
291 : : unsigned long timeout);
292 : :
293 : : bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all);
294 : :
295 : : #endif /* _LINUX_RESERVATION_H */
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