1 /* 1
2 * Header file for reservations for dma-buf an
3 *
4 * Copyright(C) 2011 Linaro Limited. All right
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@canoni
11 * Thomas Hellstrom <thellstrom-at-vmware-dot-
12 *
13 * Based on bo.c which bears the following cop
14 * but is dual licensed:
15 *
16 * Copyright (c) 2006-2009 VMware, Inc., Palo
17 * All Rights Reserved.
18 *
19 * Permission is hereby granted, free of charg
20 * copy of this software and associated docume
21 * "Software"), to deal in the Software withou
22 * without limitation the rights to use, copy,
23 * distribute, sub license, and/or sell copies
24 * permit persons to whom the Software is furn
25 * the following conditions:
26 *
27 * The above copyright notice and this permiss
28 * next paragraph) shall be included in all co
29 * of the Software.
30 *
31 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT W
32 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE W
33 * FITNESS FOR A PARTICULAR PURPOSE AND NON-IN
34 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS S
35 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN A
36 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNE
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 struct dma_resv_list;
51
52 /**
53 * enum dma_resv_usage - how the fences from a
54 *
55 * This enum describes the different use cases
56 * controls which fences are returned when que
57 *
58 * An important fact is that there is the orde
59 * when the dma_resv object is asked for fence
60 * for the lower use case are returned as well
61 *
62 * For example when asking for WRITE fences th
63 * as well. Similar when asked for READ fences
64 * fences are returned as well.
65 *
66 * Already used fences can be promoted in the
67 * DMA_RESV_USAGE_BOOKKEEP could become DMA_RE
68 * with this usage. But fences can never be de
69 * with DMA_RESV_USAGE_WRITE could become DMA_
70 */
71 enum dma_resv_usage {
72 /**
73 * @DMA_RESV_USAGE_KERNEL: For in kern
74 *
75 * This should only be used for things
76 * with a DMA hardware engine for the
77 * management.
78 *
79 * Drivers *always* must wait for thos
80 * resource protected by the dma_resv
81 * that is when the resource is known
82 * pinning it previously.
83 */
84 DMA_RESV_USAGE_KERNEL,
85
86 /**
87 * @DMA_RESV_USAGE_WRITE: Implicit wri
88 *
89 * This should only be used for usersp
90 * an implicit write dependency.
91 */
92 DMA_RESV_USAGE_WRITE,
93
94 /**
95 * @DMA_RESV_USAGE_READ: Implicit read
96 *
97 * This should only be used for usersp
98 * an implicit read dependency.
99 */
100 DMA_RESV_USAGE_READ,
101
102 /**
103 * @DMA_RESV_USAGE_BOOKKEEP: No implic
104 *
105 * This should be used by submissions
106 * any implicit synchronization.
107 *
108 * The most common case are preemption
109 * flushes as well as explicit synced
110 *
111 * Explicit synced user user submissio
112 * DMA_RESV_USAGE_READ or DMA_RESV_USA
113 * dma_buf_import_sync_file() when imp
114 * become necessary after initial addi
115 */
116 DMA_RESV_USAGE_BOOKKEEP
117 };
118
119 /**
120 * dma_resv_usage_rw - helper for implicit syn
121 * @write: true if we create a new implicit sy
122 *
123 * This returns the implicit synchronization u
124 * see enum dma_resv_usage and &dma_buf.resv.
125 */
126 static inline enum dma_resv_usage dma_resv_usa
127 {
128 /* This looks confusing at first sight
129 *
130 * The rational is that new write oper
131 * existing read and write operations
132 * But a new read operation only needs
133 * operations to finish.
134 */
135 return write ? DMA_RESV_USAGE_READ : D
136 }
137
138 /**
139 * struct dma_resv - a reservation object mana
140 *
141 * This is a container for dma_fence objects w
142 * cases.
143 *
144 * One use is to synchronize cross-driver acce
145 * dynamic buffer management or just to handle
146 * different users of the buffer in userspace.
147 * in-depth discussion.
148 *
149 * The other major use is to manage access and
150 * buffer based memory manager. struct ttm_buf
151 * example here, since this is where reservati
152 * use in drivers is spreading and some driver
153 * drm_gem_object with the same scheme.
154 */
155 struct dma_resv {
156 /**
157 * @lock:
158 *
159 * Update side lock. Don't use directl
160 * functions like dma_resv_lock() and
161 *
162 * Drivers which use the reservation o
163 * also use this lock to protect buffe
164 * allocation policies or throughout c
165 */
166 struct ww_mutex lock;
167
168 /**
169 * @fences:
170 *
171 * Array of fences which where added t
172 *
173 * A new fence is added by calling dma
174 * often needs to be done past the poi
175 * submission it cannot fail, and ther
176 * reserved by calling dma_resv_reserv
177 */
178 struct dma_resv_list __rcu *fences;
179 };
180
181 /**
182 * struct dma_resv_iter - current position int
183 *
184 * Don't touch this directly in the driver, us
185 *
186 * IMPORTANT
187 *
188 * When using the lockless iterators like dma_
189 * dma_resv_for_each_fence_unlocked() beware t
190 * Code which accumulates statistics or simila
191 * dma_resv_iter_is_restarted().
192 */
193 struct dma_resv_iter {
194 /** @obj: The dma_resv object we itera
195 struct dma_resv *obj;
196
197 /** @usage: Return fences with this us
198 enum dma_resv_usage usage;
199
200 /** @fence: the currently handled fenc
201 struct dma_fence *fence;
202
203 /** @fence_usage: the usage of the cur
204 enum dma_resv_usage fence_usage;
205
206 /** @index: index into the shared fenc
207 unsigned int index;
208
209 /** @fences: the shared fences; privat
210 struct dma_resv_list *fences;
211
212 /** @num_fences: number of fences */
213 unsigned int num_fences;
214
215 /** @is_restarted: true if this is the
216 bool is_restarted;
217 };
218
219 struct dma_fence *dma_resv_iter_first_unlocked
220 struct dma_fence *dma_resv_iter_next_unlocked(
221 struct dma_fence *dma_resv_iter_first(struct d
222 struct dma_fence *dma_resv_iter_next(struct dm
223
224 /**
225 * dma_resv_iter_begin - initialize a dma_resv
226 * @cursor: The dma_resv_iter object to initia
227 * @obj: The dma_resv object which we want to
228 * @usage: controls which fences to include, s
229 */
230 static inline void dma_resv_iter_begin(struct
231 struct
232 enum dm
233 {
234 cursor->obj = obj;
235 cursor->usage = usage;
236 cursor->fence = NULL;
237 }
238
239 /**
240 * dma_resv_iter_end - cleanup a dma_resv_iter
241 * @cursor: the dma_resv_iter object which sho
242 *
243 * Make sure that the reference to the fence i
244 * dropped.
245 */
246 static inline void dma_resv_iter_end(struct dm
247 {
248 dma_fence_put(cursor->fence);
249 }
250
251 /**
252 * dma_resv_iter_usage - Return the usage of t
253 * @cursor: the cursor of the current position
254 *
255 * Returns the usage of the currently processe
256 */
257 static inline enum dma_resv_usage
258 dma_resv_iter_usage(struct dma_resv_iter *curs
259 {
260 return cursor->fence_usage;
261 }
262
263 /**
264 * dma_resv_iter_is_restarted - test if this i
265 * @cursor: the cursor with the current positi
266 *
267 * Return true if this is the first fence in a
268 */
269 static inline bool dma_resv_iter_is_restarted(
270 {
271 return cursor->is_restarted;
272 }
273
274 /**
275 * dma_resv_for_each_fence_unlocked - unlocked
276 * @cursor: a struct dma_resv_iter pointer
277 * @fence: the current fence
278 *
279 * Iterate over the fences in a struct dma_res
280 * &dma_resv.lock and using RCU instead. The c
281 * with dma_resv_iter_begin() and cleaned up w
282 * the iterator a reference to the dma_fence i
283 *
284 * Beware that the iterator can be restarted w
285 * @cursor is modified. Code which accumulates
286 * check for this with dma_resv_iter_is_restar
287 * lock iterator dma_resv_for_each_fence() whe
288 */
289 #define dma_resv_for_each_fence_unlocked(curso
290 for (fence = dma_resv_iter_first_unloc
291 fence; fence = dma_resv_iter_next
292
293 /**
294 * dma_resv_for_each_fence - fence iterator
295 * @cursor: a struct dma_resv_iter pointer
296 * @obj: a dma_resv object pointer
297 * @usage: controls which fences to return
298 * @fence: the current fence
299 *
300 * Iterate over the fences in a struct dma_res
301 * &dma_resv.lock. @all_fences controls if the
302 * well. The cursor initialisation is part of
303 * valid as long as the lock is held and so no
304 * taken.
305 */
306 #define dma_resv_for_each_fence(cursor, obj, u
307 for (dma_resv_iter_begin(cursor, obj,
308 fence = dma_resv_iter_first(curso
309 fence = dma_resv_iter_next(cursor
310
311 #define dma_resv_held(obj) lockdep_is_held(&(o
312 #define dma_resv_assert_held(obj) lockdep_asse
313
314 #ifdef CONFIG_DEBUG_MUTEXES
315 void dma_resv_reset_max_fences(struct dma_resv
316 #else
317 static inline void dma_resv_reset_max_fences(s
318 #endif
319
320 /**
321 * dma_resv_lock - lock the reservation object
322 * @obj: the reservation object
323 * @ctx: the locking context
324 *
325 * Locks the reservation object for exclusive
326 * that the lock is only against other writers
327 * with a writer under RCU. The seqlock is use
328 * overlap with a writer.
329 *
330 * As the reservation object may be locked by
331 * undefined order, a #ww_acquire_ctx is passe
332 * is detected. See ww_mutex_lock() and ww_acq
333 * object may be locked by itself by passing N
334 *
335 * When a die situation is indicated by return
336 * @ctx must be unlocked and then dma_resv_loc
337 *
338 * Unlocked by calling dma_resv_unlock().
339 *
340 * See also dma_resv_lock_interruptible() for
341 */
342 static inline int dma_resv_lock(struct dma_res
343 struct ww_acqu
344 {
345 return ww_mutex_lock(&obj->lock, ctx);
346 }
347
348 /**
349 * dma_resv_lock_interruptible - lock the rese
350 * @obj: the reservation object
351 * @ctx: the locking context
352 *
353 * Locks the reservation object interruptible
354 * modification. Note, that the lock is only a
355 * will run concurrently with a writer under R
356 * notify readers if they overlap with a write
357 *
358 * As the reservation object may be locked by
359 * undefined order, a #ww_acquire_ctx is passe
360 * is detected. See ww_mutex_lock() and ww_acq
361 * object may be locked by itself by passing N
362 *
363 * When a die situation is indicated by return
364 * @ctx must be unlocked and then dma_resv_loc
365 * @obj.
366 *
367 * Unlocked by calling dma_resv_unlock().
368 */
369 static inline int dma_resv_lock_interruptible(
370
371 {
372 return ww_mutex_lock_interruptible(&ob
373 }
374
375 /**
376 * dma_resv_lock_slow - slowpath lock the rese
377 * @obj: the reservation object
378 * @ctx: the locking context
379 *
380 * Acquires the reservation object after a die
381 * will sleep until the lock becomes available
382 * well.
383 *
384 * See also dma_resv_lock_slow_interruptible()
385 */
386 static inline void dma_resv_lock_slow(struct d
387 struct w
388 {
389 ww_mutex_lock_slow(&obj->lock, ctx);
390 }
391
392 /**
393 * dma_resv_lock_slow_interruptible - slowpath
394 * object, interruptible
395 * @obj: the reservation object
396 * @ctx: the locking context
397 *
398 * Acquires the reservation object interruptib
399 * will sleep until the lock becomes available
400 * dma_resv_lock_interruptible() as well.
401 */
402 static inline int dma_resv_lock_slow_interrupt
403
404 {
405 return ww_mutex_lock_slow_interruptibl
406 }
407
408 /**
409 * dma_resv_trylock - trylock the reservation
410 * @obj: the reservation object
411 *
412 * Tries to lock the reservation object for ex
413 * Note, that the lock is only against other w
414 * concurrently with a writer under RCU. The s
415 * if they overlap with a writer.
416 *
417 * Also note that since no context is provided
418 * possible, which is also not needed for a tr
419 *
420 * Returns true if the lock was acquired, fals
421 */
422 static inline bool __must_check dma_resv_trylo
423 {
424 return ww_mutex_trylock(&obj->lock, NU
425 }
426
427 /**
428 * dma_resv_is_locked - is the reservation obj
429 * @obj: the reservation object
430 *
431 * Returns true if the mutex is locked, false
432 */
433 static inline bool dma_resv_is_locked(struct d
434 {
435 return ww_mutex_is_locked(&obj->lock);
436 }
437
438 /**
439 * dma_resv_locking_ctx - returns the context
440 * @obj: the reservation object
441 *
442 * Returns the context used to lock a reservat
443 * was used or the object is not locked at all
444 *
445 * WARNING: This interface is pretty horrible,
446 * doesn't pass the struct ww_acquire_ctx arou
447 * Everyone else just uses it to check whether
448 * not.
449 */
450 static inline struct ww_acquire_ctx *dma_resv_
451 {
452 return READ_ONCE(obj->lock.ctx);
453 }
454
455 /**
456 * dma_resv_unlock - unlock the reservation ob
457 * @obj: the reservation object
458 *
459 * Unlocks the reservation object following ex
460 */
461 static inline void dma_resv_unlock(struct dma_
462 {
463 dma_resv_reset_max_fences(obj);
464 ww_mutex_unlock(&obj->lock);
465 }
466
467 void dma_resv_init(struct dma_resv *obj);
468 void dma_resv_fini(struct dma_resv *obj);
469 int dma_resv_reserve_fences(struct dma_resv *o
470 void dma_resv_add_fence(struct dma_resv *obj,
471 enum dma_resv_usage us
472 void dma_resv_replace_fences(struct dma_resv *
473 struct dma_fence
474 enum dma_resv_usa
475 int dma_resv_get_fences(struct dma_resv *obj,
476 unsigned int *num_fenc
477 int dma_resv_get_singleton(struct dma_resv *ob
478 struct dma_fence **
479 int dma_resv_copy_fences(struct dma_resv *dst,
480 long dma_resv_wait_timeout(struct dma_resv *ob
481 bool intr, unsigned
482 void dma_resv_set_deadline(struct dma_resv *ob
483 ktime_t deadline);
484 bool dma_resv_test_signaled(struct dma_resv *o
485 void dma_resv_describe(struct dma_resv *obj, s
486
487 #endif /* _LINUX_RESERVATION_H */
488
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