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.
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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
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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;
51 * struct dma_resv_list - a list of shared fences
52 * @rcu: for internal use
53 * @shared_count: table of shared fences
54 * @shared_max: for growing shared fence table
55 * @shared: shared fence table
57 struct dma_resv_list {
59 u32 shared_count, shared_max;
60 struct dma_fence __rcu *shared[];
64 * struct dma_resv - a reservation object manages fences for a buffer
65 * @lock: update side lock
66 * @seq: sequence count for managing RCU read-side synchronization
67 * @fence_excl: the exclusive fence, if there is one currently
68 * @fence: list of current shared fences
73 struct dma_fence __rcu *fence_excl;
74 struct dma_resv_list __rcu *fence;
77 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
78 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
81 * dma_resv_get_excl - get the reservation object's
82 * exclusive fence, with update-side lock held
83 * @obj: the reservation object
85 * Returns the exclusive fence (if any). Does NOT take a
86 * reference. Writers must hold obj->lock, readers may only
87 * hold a RCU read side lock.
90 * The exclusive fence or NULL
92 static inline struct dma_fence *dma_resv_get_excl(struct dma_resv *obj)
94 return rcu_dereference_protected(obj->fence_excl,
99 * dma_resv_get_list - get the reservation object's
100 * shared fence list, with update-side lock held
101 * @obj: the reservation object
103 * Returns the shared fence list. Does NOT take references to
104 * the fence. The obj->lock must be held.
106 static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj)
108 return rcu_dereference_protected(obj->fence,
113 * dma_resv_fences - read consistent fence pointers
114 * @obj: reservation object where we get the fences from
115 * @excl: pointer for the exclusive fence
116 * @list: pointer for the shared fence list
118 * Make sure we have a consisten exclusive fence and shared fence list.
119 * Must be called with rcu read side lock held.
121 static inline void dma_resv_fences(struct dma_resv *obj,
122 struct dma_fence **excl,
123 struct dma_resv_list **list,
127 *excl = rcu_dereference(obj->fence_excl);
128 *list = rcu_dereference(obj->fence);
129 *shared_count = *list ? (*list)->shared_count : 0;
130 smp_rmb(); /* See dma_resv_add_excl_fence */
131 } while (rcu_access_pointer(obj->fence_excl) != *excl);
135 * dma_resv_get_excl_rcu - get the reservation object's
136 * exclusive fence, without lock held.
137 * @obj: the reservation object
139 * If there is an exclusive fence, this atomically increments it's
140 * reference count and returns it.
143 * The exclusive fence or NULL if none
145 static inline struct dma_fence *dma_resv_get_excl_rcu(struct dma_resv *obj)
147 struct dma_fence *fence;
149 if (!rcu_access_pointer(obj->fence_excl))
153 fence = dma_fence_get_rcu_safe(&obj->fence_excl);
160 * dma_resv_lock - lock the reservation object
161 * @obj: the reservation object
162 * @ctx: the locking context
164 * Locks the reservation object for exclusive access and modification. Note,
165 * that the lock is only against other writers, readers will run concurrently
166 * with a writer under RCU. The seqlock is used to notify readers if they
167 * overlap with a writer.
169 * As the reservation object may be locked by multiple parties in an
170 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
171 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
172 * object may be locked by itself by passing NULL as @ctx.
174 static inline int dma_resv_lock(struct dma_resv *obj,
175 struct ww_acquire_ctx *ctx)
177 return ww_mutex_lock(&obj->lock, ctx);
181 * dma_resv_lock_interruptible - lock the reservation object
182 * @obj: the reservation object
183 * @ctx: the locking context
185 * Locks the reservation object interruptible for exclusive access and
186 * modification. Note, that the lock is only against other writers, readers
187 * will run concurrently with a writer under RCU. The seqlock is used to
188 * notify readers if they overlap with a writer.
190 * As the reservation object may be locked by multiple parties in an
191 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
192 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
193 * object may be locked by itself by passing NULL as @ctx.
195 static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
196 struct ww_acquire_ctx *ctx)
198 return ww_mutex_lock_interruptible(&obj->lock, ctx);
202 * dma_resv_lock_slow - slowpath lock the reservation object
203 * @obj: the reservation object
204 * @ctx: the locking context
206 * Acquires the reservation object after a die case. This function
207 * will sleep until the lock becomes available. See dma_resv_lock() as
210 static inline void dma_resv_lock_slow(struct dma_resv *obj,
211 struct ww_acquire_ctx *ctx)
213 ww_mutex_lock_slow(&obj->lock, ctx);
217 * dma_resv_lock_slow_interruptible - slowpath lock the reservation
218 * object, interruptible
219 * @obj: the reservation object
220 * @ctx: the locking context
222 * Acquires the reservation object interruptible after a die case. This function
223 * will sleep until the lock becomes available. See
224 * dma_resv_lock_interruptible() as well.
226 static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
227 struct ww_acquire_ctx *ctx)
229 return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
233 * dma_resv_trylock - trylock the reservation object
234 * @obj: the reservation object
236 * Tries to lock the reservation object for exclusive access and modification.
237 * Note, that the lock is only against other writers, readers will run
238 * concurrently with a writer under RCU. The seqlock is used to notify readers
239 * if they overlap with a writer.
241 * Also note that since no context is provided, no deadlock protection is
244 * Returns true if the lock was acquired, false otherwise.
246 static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
248 return ww_mutex_trylock(&obj->lock);
252 * dma_resv_is_locked - is the reservation object locked
253 * @obj: the reservation object
255 * Returns true if the mutex is locked, false if unlocked.
257 static inline bool dma_resv_is_locked(struct dma_resv *obj)
259 return ww_mutex_is_locked(&obj->lock);
263 * dma_resv_locking_ctx - returns the context used to lock the object
264 * @obj: the reservation object
266 * Returns the context used to lock a reservation object or NULL if no context
267 * was used or the object is not locked at all.
269 static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
271 return READ_ONCE(obj->lock.ctx);
275 * dma_resv_unlock - unlock the reservation object
276 * @obj: the reservation object
278 * Unlocks the reservation object following exclusive access.
280 static inline void dma_resv_unlock(struct dma_resv *obj)
282 #ifdef CONFIG_DEBUG_MUTEXES
283 /* Test shared fence slot reservation */
284 if (rcu_access_pointer(obj->fence)) {
285 struct dma_resv_list *fence = dma_resv_get_list(obj);
287 fence->shared_max = fence->shared_count;
290 ww_mutex_unlock(&obj->lock);
293 void dma_resv_init(struct dma_resv *obj);
294 void dma_resv_fini(struct dma_resv *obj);
295 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
296 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
298 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
300 int dma_resv_get_fences_rcu(struct dma_resv *obj,
301 struct dma_fence **pfence_excl,
302 unsigned *pshared_count,
303 struct dma_fence ***pshared);
305 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
307 long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
308 unsigned long timeout);
310 bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all);
312 #endif /* _LINUX_RESERVATION_H */