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Linux/include/linux/reservation.h

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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 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  */
 59 struct 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  */
 72 struct 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  */
 88 static inline void
 89 reservation_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  */
102 static inline void
103 reservation_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  */
136 static inline struct reservation_object_list *
137 reservation_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  */
158 static inline int
159 reservation_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  */
180 static inline int
181 reservation_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  */
202 static inline bool __must_check
203 reservation_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  */
214 static inline void
215 reservation_object_unlock(struct reservation_object *obj)
216 {
217 #ifdef CONFIG_DEBUG_MUTEXES
218         /* Test shared fence slot reservation */
219         if (obj->fence)
220                 obj->fence->shared_max = obj->fence->shared_count;
221 #endif
222         ww_mutex_unlock(&obj->lock);
223 }
224 
225 /**
226  * reservation_object_get_excl - get the reservation object's
227  * exclusive fence, with update-side lock held
228  * @obj: the reservation object
229  *
230  * Returns the exclusive fence (if any).  Does NOT take a
231  * reference.  The obj->lock must be held.
232  *
233  * RETURNS
234  * The exclusive fence or NULL
235  */
236 static inline struct dma_fence *
237 reservation_object_get_excl(struct reservation_object *obj)
238 {
239         return rcu_dereference_protected(obj->fence_excl,
240                                          reservation_object_held(obj));
241 }
242 
243 /**
244  * reservation_object_get_excl_rcu - get the reservation object's
245  * exclusive fence, without lock held.
246  * @obj: the reservation object
247  *
248  * If there is an exclusive fence, this atomically increments it's
249  * reference count and returns it.
250  *
251  * RETURNS
252  * The exclusive fence or NULL if none
253  */
254 static inline struct dma_fence *
255 reservation_object_get_excl_rcu(struct reservation_object *obj)
256 {
257         struct dma_fence *fence;
258 
259         if (!rcu_access_pointer(obj->fence_excl))
260                 return NULL;
261 
262         rcu_read_lock();
263         fence = dma_fence_get_rcu_safe(&obj->fence_excl);
264         rcu_read_unlock();
265 
266         return fence;
267 }
268 
269 int reservation_object_reserve_shared(struct reservation_object *obj,
270                                       unsigned int num_fences);
271 void reservation_object_add_shared_fence(struct reservation_object *obj,
272                                          struct dma_fence *fence);
273 
274 void reservation_object_add_excl_fence(struct reservation_object *obj,
275                                        struct dma_fence *fence);
276 
277 int reservation_object_get_fences_rcu(struct reservation_object *obj,
278                                       struct dma_fence **pfence_excl,
279                                       unsigned *pshared_count,
280                                       struct dma_fence ***pshared);
281 
282 int reservation_object_copy_fences(struct reservation_object *dst,
283                                    struct reservation_object *src);
284 
285 long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
286                                          bool wait_all, bool intr,
287                                          unsigned long timeout);
288 
289 bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
290                                           bool test_all);
291 
292 #endif /* _LINUX_RESERVATION_H */
293 

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