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
50 /**
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
56 */
57 struct dma_resv_list {
58 struct rcu_head rcu;
59 u32 shared_count, shared_max;
60 struct dma_fence __rcu *shared[];
61 };
62
63 /**
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
69 */
70 struct dma_resv {
71 struct ww_mutex lock;
72 seqcount_ww_mutex_t seq;
73
74 struct dma_fence __rcu *fence_excl;
75 struct dma_resv_list __rcu *fence;
76 };
77
78 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
79 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
80
81 /**
82 * dma_resv_get_list - get the reservation object's
83 * shared fence list, with update-side lock held
84 * @obj: the reservation object
85 *
86 * Returns the shared fence list. Does NOT take references to
87 * the fence. The obj->lock must be held.
88 */
dma_resv_get_list(struct dma_resv * obj)89 static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj)
90 {
91 return rcu_dereference_protected(obj->fence,
92 dma_resv_held(obj));
93 }
94
95 /**
96 * dma_resv_lock - lock the reservation object
97 * @obj: the reservation object
98 * @ctx: the locking context
99 *
100 * Locks the reservation object for exclusive access and modification. Note,
101 * that the lock is only against other writers, readers will run concurrently
102 * with a writer under RCU. The seqlock is used to notify readers if they
103 * overlap with a writer.
104 *
105 * As the reservation object may be locked by multiple parties in an
106 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
107 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
108 * object may be locked by itself by passing NULL as @ctx.
109 */
dma_resv_lock(struct dma_resv * obj,struct ww_acquire_ctx * ctx)110 static inline int dma_resv_lock(struct dma_resv *obj,
111 struct ww_acquire_ctx *ctx)
112 {
113 return ww_mutex_lock(&obj->lock, ctx);
114 }
115
116 /**
117 * dma_resv_lock_interruptible - lock the reservation object
118 * @obj: the reservation object
119 * @ctx: the locking context
120 *
121 * Locks the reservation object interruptible for exclusive access and
122 * modification. Note, that the lock is only against other writers, readers
123 * will run concurrently with a writer under RCU. The seqlock is used to
124 * notify readers if they overlap with a writer.
125 *
126 * As the reservation object may be locked by multiple parties in an
127 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
128 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
129 * object may be locked by itself by passing NULL as @ctx.
130 */
dma_resv_lock_interruptible(struct dma_resv * obj,struct ww_acquire_ctx * ctx)131 static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
132 struct ww_acquire_ctx *ctx)
133 {
134 return ww_mutex_lock_interruptible(&obj->lock, ctx);
135 }
136
137 /**
138 * dma_resv_lock_slow - slowpath lock the reservation object
139 * @obj: the reservation object
140 * @ctx: the locking context
141 *
142 * Acquires the reservation object after a die case. This function
143 * will sleep until the lock becomes available. See dma_resv_lock() as
144 * well.
145 */
dma_resv_lock_slow(struct dma_resv * obj,struct ww_acquire_ctx * ctx)146 static inline void dma_resv_lock_slow(struct dma_resv *obj,
147 struct ww_acquire_ctx *ctx)
148 {
149 ww_mutex_lock_slow(&obj->lock, ctx);
150 }
151
152 /**
153 * dma_resv_lock_slow_interruptible - slowpath lock the reservation
154 * object, interruptible
155 * @obj: the reservation object
156 * @ctx: the locking context
157 *
158 * Acquires the reservation object interruptible after a die case. This function
159 * will sleep until the lock becomes available. See
160 * dma_resv_lock_interruptible() as well.
161 */
dma_resv_lock_slow_interruptible(struct dma_resv * obj,struct ww_acquire_ctx * ctx)162 static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
163 struct ww_acquire_ctx *ctx)
164 {
165 return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
166 }
167
168 /**
169 * dma_resv_trylock - trylock the reservation object
170 * @obj: the reservation object
171 *
172 * Tries to lock the reservation object for exclusive access and modification.
173 * Note, that the lock is only against other writers, readers will run
174 * concurrently with a writer under RCU. The seqlock is used to notify readers
175 * if they overlap with a writer.
176 *
177 * Also note that since no context is provided, no deadlock protection is
178 * possible.
179 *
180 * Returns true if the lock was acquired, false otherwise.
181 */
dma_resv_trylock(struct dma_resv * obj)182 static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
183 {
184 return ww_mutex_trylock(&obj->lock);
185 }
186
187 /**
188 * dma_resv_is_locked - is the reservation object locked
189 * @obj: the reservation object
190 *
191 * Returns true if the mutex is locked, false if unlocked.
192 */
dma_resv_is_locked(struct dma_resv * obj)193 static inline bool dma_resv_is_locked(struct dma_resv *obj)
194 {
195 return ww_mutex_is_locked(&obj->lock);
196 }
197
198 /**
199 * dma_resv_locking_ctx - returns the context used to lock the object
200 * @obj: the reservation object
201 *
202 * Returns the context used to lock a reservation object or NULL if no context
203 * was used or the object is not locked at all.
204 */
dma_resv_locking_ctx(struct dma_resv * obj)205 static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
206 {
207 return READ_ONCE(obj->lock.ctx);
208 }
209
210 /**
211 * dma_resv_unlock - unlock the reservation object
212 * @obj: the reservation object
213 *
214 * Unlocks the reservation object following exclusive access.
215 */
dma_resv_unlock(struct dma_resv * obj)216 static inline void dma_resv_unlock(struct dma_resv *obj)
217 {
218 #ifdef CONFIG_DEBUG_MUTEXES
219 /* Test shared fence slot reservation */
220 if (rcu_access_pointer(obj->fence)) {
221 struct dma_resv_list *fence = dma_resv_get_list(obj);
222
223 fence->shared_max = fence->shared_count;
224 }
225 #endif
226 ww_mutex_unlock(&obj->lock);
227 }
228
229 /**
230 * dma_resv_get_excl - get the reservation object's
231 * exclusive fence, with update-side lock held
232 * @obj: the reservation object
233 *
234 * Returns the exclusive fence (if any). Does NOT take a
235 * reference. Writers must hold obj->lock, readers may only
236 * hold a RCU read side lock.
237 *
238 * RETURNS
239 * The exclusive fence or NULL
240 */
241 static inline struct dma_fence *
dma_resv_get_excl(struct dma_resv * obj)242 dma_resv_get_excl(struct dma_resv *obj)
243 {
244 return rcu_dereference_protected(obj->fence_excl,
245 dma_resv_held(obj));
246 }
247
248 /**
249 * dma_resv_get_excl_rcu - get the reservation object's
250 * exclusive fence, without lock held.
251 * @obj: the reservation object
252 *
253 * If there is an exclusive fence, this atomically increments it's
254 * reference count and returns it.
255 *
256 * RETURNS
257 * The exclusive fence or NULL if none
258 */
259 static inline struct dma_fence *
dma_resv_get_excl_rcu(struct dma_resv * obj)260 dma_resv_get_excl_rcu(struct dma_resv *obj)
261 {
262 struct dma_fence *fence;
263
264 if (!rcu_access_pointer(obj->fence_excl))
265 return NULL;
266
267 rcu_read_lock();
268 fence = dma_fence_get_rcu_safe(&obj->fence_excl);
269 rcu_read_unlock();
270
271 return fence;
272 }
273
274 void dma_resv_init(struct dma_resv *obj);
275 void dma_resv_fini(struct dma_resv *obj);
276 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
277 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
278
279 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
280
281 int dma_resv_get_fences_rcu(struct dma_resv *obj,
282 struct dma_fence **pfence_excl,
283 unsigned *pshared_count,
284 struct dma_fence ***pshared);
285
286 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
287
288 long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
289 unsigned long timeout);
290
291 bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all);
292
293 #endif /* _LINUX_RESERVATION_H */
294
