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 static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj)
92 {
93 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 static inline int dma_resv_lock(struct dma_resv *obj,
113 struct ww_acquire_ctx *ctx)
114 {
115 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 static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
134 struct ww_acquire_ctx *ctx)
135 {
136 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 static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
165 struct ww_acquire_ctx *ctx)
166 {
167 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 static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
185 {
186 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 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 ww_mutex_unlock(&obj->lock);
229 }
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 dma_resv_get_excl(struct dma_resv *obj)
245 {
246 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 dma_resv_get_excl_rcu(struct dma_resv *obj)
263 {
264 struct dma_fence *fence;
265
266 if (!rcu_access_pointer(obj->fence_excl))
267 return NULL;
268
269 rcu_read_lock();
270 fence = dma_fence_get_rcu_safe(&obj->fence_excl);
271 rcu_read_unlock();
272
273 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 */