2 * Header file for reservations for dma-buf and ttm
4 * Copyright(C) 2011 Linaro Limited. All rights reserved.
5 * Copyright (C) 2012-2013 Canonical Ltd
6 * Copyright (C) 2012 Texas Instruments
9 * Rob Clark <robdclark@gmail.com>
10 * Maarten Lankhorst <maarten.lankhorst@canonical.com>
11 * Thomas Hellstrom <thellstrom-at-vmware-dot-com>
13 * Based on bo.c which bears the following copyright notice,
14 * but is dual licensed:
16 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
17 * All Rights Reserved.
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:
27 * The above copyright notice and this permission notice (including the
28 * next paragraph) shall be included in all copies or substantial portions
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,
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39 #ifndef _LINUX_RESERVATION_H
40 #define _LINUX_RESERVATION_H
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>
48 extern struct ww_class reservation_ww_class;
49 extern struct lock_class_key reservation_seqcount_class;
50 extern const char reservation_seqcount_string[];
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
59 struct reservation_object_list {
61 u32 shared_count, shared_max;
62 struct dma_fence __rcu *shared[];
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
72 struct reservation_object {
76 struct dma_fence __rcu *fence_excl;
77 struct reservation_object_list __rcu *fence;
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)
85 * reservation_object_get_excl - get the reservation object's
86 * exclusive fence, with update-side lock held
87 * @obj: the reservation object
89 * Returns the exclusive fence (if any). Does NOT take a
90 * reference. Writers must hold obj->lock, readers may only
91 * hold a RCU read side lock.
94 * The exclusive fence or NULL
96 static inline struct dma_fence *
97 reservation_object_get_excl(struct reservation_object *obj)
99 return rcu_dereference_protected(obj->fence_excl,
100 reservation_object_held(obj));
104 * reservation_object_get_list - get the reservation object's
105 * shared fence list, with update-side lock held
106 * @obj: the reservation object
108 * Returns the shared fence list. Does NOT take references to
109 * the fence. The obj->lock must be held.
111 static inline struct reservation_object_list *
112 reservation_object_get_list(struct reservation_object *obj)
114 return rcu_dereference_protected(obj->fence,
115 reservation_object_held(obj));
119 * reservation_object_fences - read consistent fence pointers
120 * @obj: reservation object where we get the fences from
121 * @excl: pointer for the exclusive fence
122 * @list: pointer for the shared fence list
124 * Make sure we have a consisten exclusive fence and shared fence list.
125 * Must be called with rcu read side lock held.
128 reservation_object_fences(struct reservation_object *obj,
129 struct dma_fence **excl,
130 struct reservation_object_list **list,
136 seq = read_seqcount_begin(&obj->seq);
137 *excl = rcu_dereference(obj->fence_excl);
138 *list = rcu_dereference(obj->fence);
139 *shared_count = *list ? (*list)->shared_count : 0;
140 } while (read_seqcount_retry(&obj->seq, seq));
144 * reservation_object_get_excl_rcu - get the reservation object's
145 * exclusive fence, without lock held.
146 * @obj: the reservation object
148 * If there is an exclusive fence, this atomically increments it's
149 * reference count and returns it.
152 * The exclusive fence or NULL if none
154 static inline struct dma_fence *
155 reservation_object_get_excl_rcu(struct reservation_object *obj)
157 struct dma_fence *fence;
159 if (!rcu_access_pointer(obj->fence_excl))
163 fence = dma_fence_get_rcu_safe(&obj->fence_excl);
170 * reservation_object_lock - lock the reservation object
171 * @obj: the reservation object
172 * @ctx: the locking context
174 * Locks the reservation object for exclusive access and modification. Note,
175 * that the lock is only against other writers, readers will run concurrently
176 * with a writer under RCU. The seqlock is used to notify readers if they
177 * overlap with a writer.
179 * As the reservation object may be locked by multiple parties in an
180 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
181 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
182 * object may be locked by itself by passing NULL as @ctx.
185 reservation_object_lock(struct reservation_object *obj,
186 struct ww_acquire_ctx *ctx)
188 return ww_mutex_lock(&obj->lock, ctx);
192 * reservation_object_lock_interruptible - lock the reservation object
193 * @obj: the reservation object
194 * @ctx: the locking context
196 * Locks the reservation object interruptible for exclusive access and
197 * modification. Note, that the lock is only against other writers, readers
198 * will run concurrently with a writer under RCU. The seqlock is used to
199 * notify readers if they overlap with a writer.
201 * As the reservation object may be locked by multiple parties in an
202 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
203 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
204 * object may be locked by itself by passing NULL as @ctx.
207 reservation_object_lock_interruptible(struct reservation_object *obj,
208 struct ww_acquire_ctx *ctx)
210 return ww_mutex_lock_interruptible(&obj->lock, ctx);
214 * reservation_object_lock_slow - slowpath lock the reservation object
215 * @obj: the reservation object
216 * @ctx: the locking context
218 * Acquires the reservation object after a die case. This function
219 * will sleep until the lock becomes available. See reservation_object_lock() as
223 reservation_object_lock_slow(struct reservation_object *obj,
224 struct ww_acquire_ctx *ctx)
226 ww_mutex_lock_slow(&obj->lock, ctx);
230 * reservation_object_lock_slow_interruptible - slowpath lock the reservation
231 * object, interruptible
232 * @obj: the reservation object
233 * @ctx: the locking context
235 * Acquires the reservation object interruptible after a die case. This function
236 * will sleep until the lock becomes available. See
237 * reservation_object_lock_interruptible() as well.
240 reservation_object_lock_slow_interruptible(struct reservation_object *obj,
241 struct ww_acquire_ctx *ctx)
243 return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
247 * reservation_object_trylock - trylock the reservation object
248 * @obj: the reservation object
250 * Tries to lock the reservation object for exclusive access and modification.
251 * Note, that the lock is only against other writers, readers will run
252 * concurrently with a writer under RCU. The seqlock is used to notify readers
253 * if they overlap with a writer.
255 * Also note that since no context is provided, no deadlock protection is
258 * Returns true if the lock was acquired, false otherwise.
260 static inline bool __must_check
261 reservation_object_trylock(struct reservation_object *obj)
263 return ww_mutex_trylock(&obj->lock);
267 * reservation_object_is_locked - is the reservation object locked
268 * @obj: the reservation object
270 * Returns true if the mutex is locked, false if unlocked.
273 reservation_object_is_locked(struct reservation_object *obj)
275 return ww_mutex_is_locked(&obj->lock);
279 * reservation_object_locking_ctx - returns the context used to lock the object
280 * @obj: the reservation object
282 * Returns the context used to lock a reservation object or NULL if no context
283 * was used or the object is not locked at all.
285 static inline struct ww_acquire_ctx *
286 reservation_object_locking_ctx(struct reservation_object *obj)
288 return READ_ONCE(obj->lock.ctx);
292 * reservation_object_unlock - unlock the reservation object
293 * @obj: the reservation object
295 * Unlocks the reservation object following exclusive access.
298 reservation_object_unlock(struct reservation_object *obj)
300 #ifdef CONFIG_DEBUG_MUTEXES
301 /* Test shared fence slot reservation */
302 if (rcu_access_pointer(obj->fence)) {
303 struct reservation_object_list *fence =
304 reservation_object_get_list(obj);
306 fence->shared_max = fence->shared_count;
309 ww_mutex_unlock(&obj->lock);
312 void reservation_object_init(struct reservation_object *obj);
313 void reservation_object_fini(struct reservation_object *obj);
314 int reservation_object_reserve_shared(struct reservation_object *obj,
315 unsigned int num_fences);
316 void reservation_object_add_shared_fence(struct reservation_object *obj,
317 struct dma_fence *fence);
319 void reservation_object_add_excl_fence(struct reservation_object *obj,
320 struct dma_fence *fence);
322 int reservation_object_get_fences_rcu(struct reservation_object *obj,
323 struct dma_fence **pfence_excl,
324 unsigned *pshared_count,
325 struct dma_fence ***pshared);
327 int reservation_object_copy_fences(struct reservation_object *dst,
328 struct reservation_object *src);
330 long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
331 bool wait_all, bool intr,
332 unsigned long timeout);
334 bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
337 #endif /* _LINUX_RESERVATION_H */