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786d7257 ML |
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: | |
0ba6b8fb | 9 | * Rob Clark <robdclark@gmail.com> |
786d7257 ML |
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 | ||
1b375dc3 | 42 | #include <linux/ww_mutex.h> |
f54d1867 | 43 | #include <linux/dma-fence.h> |
0ba6b8fb | 44 | #include <linux/slab.h> |
3c3b177a ML |
45 | #include <linux/seqlock.h> |
46 | #include <linux/rcupdate.h> | |
786d7257 ML |
47 | |
48 | extern struct ww_class reservation_ww_class; | |
49 | ||
dad6c394 | 50 | /** |
52791eee | 51 | * struct dma_resv_list - a list of shared fences |
dad6c394 RC |
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 | */ | |
52791eee | 57 | struct dma_resv_list { |
3c3b177a | 58 | struct rcu_head rcu; |
04a5faa8 | 59 | u32 shared_count, shared_max; |
f54d1867 | 60 | struct dma_fence __rcu *shared[]; |
04a5faa8 ML |
61 | }; |
62 | ||
dad6c394 | 63 | /** |
52791eee | 64 | * struct dma_resv - a reservation object manages fences for a buffer |
d9edf92d DV |
65 | * |
66 | * There are multiple uses for this, with sometimes slightly different rules in | |
67 | * how the fence slots are used. | |
68 | * | |
69 | * One use is to synchronize cross-driver access to a struct dma_buf, either for | |
70 | * dynamic buffer management or just to handle implicit synchronization between | |
71 | * different users of the buffer in userspace. See &dma_buf.resv for a more | |
72 | * in-depth discussion. | |
73 | * | |
74 | * The other major use is to manage access and locking within a driver in a | |
75 | * buffer based memory manager. struct ttm_buffer_object is the canonical | |
76 | * example here, since this is where reservation objects originated from. But | |
77 | * use in drivers is spreading and some drivers also manage struct | |
78 | * drm_gem_object with the same scheme. | |
dad6c394 | 79 | */ |
52791eee | 80 | struct dma_resv { |
d9edf92d DV |
81 | /** |
82 | * @lock: | |
83 | * | |
84 | * Update side lock. Don't use directly, instead use the wrapper | |
85 | * functions like dma_resv_lock() and dma_resv_unlock(). | |
86 | * | |
87 | * Drivers which use the reservation object to manage memory dynamically | |
88 | * also use this lock to protect buffer object state like placement, | |
89 | * allocation policies or throughout command submission. | |
90 | */ | |
786d7257 | 91 | struct ww_mutex lock; |
d9edf92d DV |
92 | |
93 | /** | |
94 | * @seq: | |
95 | * | |
96 | * Sequence count for managing RCU read-side synchronization, allows | |
97 | * read-only access to @fence_excl and @fence while ensuring we take a | |
98 | * consistent snapshot. | |
99 | */ | |
cd29f220 | 100 | seqcount_ww_mutex_t seq; |
0ba6b8fb | 101 | |
d9edf92d DV |
102 | /** |
103 | * @fence_excl: | |
104 | * | |
105 | * The exclusive fence, if there is one currently. | |
106 | * | |
107 | * There are two ways to update this fence: | |
108 | * | |
109 | * - First by calling dma_resv_add_excl_fence(), which replaces all | |
110 | * fences attached to the reservation object. To guarantee that no | |
111 | * fences are lost, this new fence must signal only after all previous | |
112 | * fences, both shared and exclusive, have signalled. In some cases it | |
113 | * is convenient to achieve that by attaching a struct dma_fence_array | |
114 | * with all the new and old fences. | |
115 | * | |
116 | * - Alternatively the fence can be set directly, which leaves the | |
117 | * shared fences unchanged. To guarantee that no fences are lost, this | |
118 | * new fence must signal only after the previous exclusive fence has | |
119 | * signalled. Since the shared fences are staying intact, it is not | |
120 | * necessary to maintain any ordering against those. If semantically | |
121 | * only a new access is added without actually treating the previous | |
122 | * one as a dependency the exclusive fences can be strung together | |
123 | * using struct dma_fence_chain. | |
124 | * | |
125 | * Note that actual semantics of what an exclusive or shared fence mean | |
126 | * is defined by the user, for reservation objects shared across drivers | |
127 | * see &dma_buf.resv. | |
128 | */ | |
f54d1867 | 129 | struct dma_fence __rcu *fence_excl; |
d9edf92d DV |
130 | |
131 | /** | |
132 | * @fence: | |
133 | * | |
134 | * List of current shared fences. | |
135 | * | |
136 | * There are no ordering constraints of shared fences against the | |
137 | * exclusive fence slot. If a waiter needs to wait for all access, it | |
138 | * has to wait for both sets of fences to signal. | |
139 | * | |
140 | * A new fence is added by calling dma_resv_add_shared_fence(). Since | |
141 | * this often needs to be done past the point of no return in command | |
142 | * submission it cannot fail, and therefore sufficient slots need to be | |
143 | * reserved by calling dma_resv_reserve_shared(). | |
144 | * | |
145 | * Note that actual semantics of what an exclusive or shared fence mean | |
146 | * is defined by the user, for reservation objects shared across drivers | |
147 | * see &dma_buf.resv. | |
148 | */ | |
52791eee | 149 | struct dma_resv_list __rcu *fence; |
786d7257 ML |
150 | }; |
151 | ||
c921ff37 CK |
152 | /** |
153 | * struct dma_resv_iter - current position into the dma_resv fences | |
154 | * | |
155 | * Don't touch this directly in the driver, use the accessor function instead. | |
156 | */ | |
157 | struct dma_resv_iter { | |
158 | /** @obj: The dma_resv object we iterate over */ | |
159 | struct dma_resv *obj; | |
160 | ||
161 | /** @all_fences: If all fences should be returned */ | |
162 | bool all_fences; | |
163 | ||
164 | /** @fence: the currently handled fence */ | |
165 | struct dma_fence *fence; | |
166 | ||
167 | /** @seq: sequence number to check for modifications */ | |
168 | unsigned int seq; | |
169 | ||
170 | /** @index: index into the shared fences */ | |
171 | unsigned int index; | |
172 | ||
5e51cc00 | 173 | /** @fences: the shared fences; private, *MUST* not dereference */ |
c921ff37 CK |
174 | struct dma_resv_list *fences; |
175 | ||
5e51cc00 TU |
176 | /** @shared_count: number of shared fences */ |
177 | unsigned int shared_count; | |
178 | ||
c921ff37 CK |
179 | /** @is_restarted: true if this is the first returned fence */ |
180 | bool is_restarted; | |
181 | }; | |
182 | ||
183 | struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor); | |
184 | struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor); | |
5baaac31 CK |
185 | struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor); |
186 | struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor); | |
c921ff37 CK |
187 | |
188 | /** | |
189 | * dma_resv_iter_begin - initialize a dma_resv_iter object | |
190 | * @cursor: The dma_resv_iter object to initialize | |
191 | * @obj: The dma_resv object which we want to iterate over | |
192 | * @all_fences: If all fences should be returned or just the exclusive one | |
193 | */ | |
194 | static inline void dma_resv_iter_begin(struct dma_resv_iter *cursor, | |
195 | struct dma_resv *obj, | |
196 | bool all_fences) | |
197 | { | |
198 | cursor->obj = obj; | |
199 | cursor->all_fences = all_fences; | |
200 | cursor->fence = NULL; | |
201 | } | |
202 | ||
203 | /** | |
204 | * dma_resv_iter_end - cleanup a dma_resv_iter object | |
205 | * @cursor: the dma_resv_iter object which should be cleaned up | |
206 | * | |
207 | * Make sure that the reference to the fence in the cursor is properly | |
208 | * dropped. | |
209 | */ | |
210 | static inline void dma_resv_iter_end(struct dma_resv_iter *cursor) | |
211 | { | |
212 | dma_fence_put(cursor->fence); | |
213 | } | |
214 | ||
215 | /** | |
216 | * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one | |
217 | * @cursor: the cursor of the current position | |
218 | * | |
219 | * Returns true if the currently returned fence is the exclusive one. | |
220 | */ | |
221 | static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor) | |
222 | { | |
223 | return cursor->index == 0; | |
224 | } | |
225 | ||
226 | /** | |
227 | * dma_resv_iter_is_restarted - test if this is the first fence after a restart | |
228 | * @cursor: the cursor with the current position | |
229 | * | |
230 | * Return true if this is the first fence in an iteration after a restart. | |
231 | */ | |
232 | static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor) | |
233 | { | |
234 | return cursor->is_restarted; | |
235 | } | |
236 | ||
237 | /** | |
238 | * dma_resv_for_each_fence_unlocked - unlocked fence iterator | |
239 | * @cursor: a struct dma_resv_iter pointer | |
240 | * @fence: the current fence | |
241 | * | |
242 | * Iterate over the fences in a struct dma_resv object without holding the | |
243 | * &dma_resv.lock and using RCU instead. The cursor needs to be initialized | |
244 | * with dma_resv_iter_begin() and cleaned up with dma_resv_iter_end(). Inside | |
245 | * the iterator a reference to the dma_fence is held and the RCU lock dropped. | |
246 | * When the dma_resv is modified the iteration starts over again. | |
247 | */ | |
248 | #define dma_resv_for_each_fence_unlocked(cursor, fence) \ | |
249 | for (fence = dma_resv_iter_first_unlocked(cursor); \ | |
250 | fence; fence = dma_resv_iter_next_unlocked(cursor)) | |
251 | ||
5baaac31 CK |
252 | /** |
253 | * dma_resv_for_each_fence - fence iterator | |
254 | * @cursor: a struct dma_resv_iter pointer | |
255 | * @obj: a dma_resv object pointer | |
256 | * @all_fences: true if all fences should be returned | |
257 | * @fence: the current fence | |
258 | * | |
259 | * Iterate over the fences in a struct dma_resv object while holding the | |
260 | * &dma_resv.lock. @all_fences controls if the shared fences are returned as | |
261 | * well. The cursor initialisation is part of the iterator and the fence stays | |
262 | * valid as long as the lock is held and so no extra reference to the fence is | |
263 | * taken. | |
264 | */ | |
265 | #define dma_resv_for_each_fence(cursor, obj, all_fences, fence) \ | |
266 | for (dma_resv_iter_begin(cursor, obj, all_fences), \ | |
267 | fence = dma_resv_iter_first(cursor); fence; \ | |
268 | fence = dma_resv_iter_next(cursor)) | |
269 | ||
52791eee CK |
270 | #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base) |
271 | #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base) | |
04a5faa8 | 272 | |
0c6b522a CK |
273 | #ifdef CONFIG_DEBUG_MUTEXES |
274 | void dma_resv_reset_shared_max(struct dma_resv *obj); | |
275 | #else | |
276 | static inline void dma_resv_reset_shared_max(struct dma_resv *obj) {} | |
277 | #endif | |
278 | ||
122020af | 279 | /** |
52791eee | 280 | * dma_resv_lock - lock the reservation object |
122020af CW |
281 | * @obj: the reservation object |
282 | * @ctx: the locking context | |
283 | * | |
284 | * Locks the reservation object for exclusive access and modification. Note, | |
285 | * that the lock is only against other writers, readers will run concurrently | |
286 | * with a writer under RCU. The seqlock is used to notify readers if they | |
287 | * overlap with a writer. | |
288 | * | |
289 | * As the reservation object may be locked by multiple parties in an | |
290 | * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle | |
291 | * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation | |
292 | * object may be locked by itself by passing NULL as @ctx. | |
d9edf92d DV |
293 | * |
294 | * When a die situation is indicated by returning -EDEADLK all locks held by | |
295 | * @ctx must be unlocked and then dma_resv_lock_slow() called on @obj. | |
296 | * | |
297 | * Unlocked by calling dma_resv_unlock(). | |
298 | * | |
299 | * See also dma_resv_lock_interruptible() for the interruptible variant. | |
122020af | 300 | */ |
52791eee CK |
301 | static inline int dma_resv_lock(struct dma_resv *obj, |
302 | struct ww_acquire_ctx *ctx) | |
122020af CW |
303 | { |
304 | return ww_mutex_lock(&obj->lock, ctx); | |
305 | } | |
306 | ||
5d276a1a | 307 | /** |
52791eee | 308 | * dma_resv_lock_interruptible - lock the reservation object |
5d276a1a CK |
309 | * @obj: the reservation object |
310 | * @ctx: the locking context | |
311 | * | |
312 | * Locks the reservation object interruptible for exclusive access and | |
313 | * modification. Note, that the lock is only against other writers, readers | |
314 | * will run concurrently with a writer under RCU. The seqlock is used to | |
315 | * notify readers if they overlap with a writer. | |
316 | * | |
317 | * As the reservation object may be locked by multiple parties in an | |
318 | * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle | |
319 | * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation | |
320 | * object may be locked by itself by passing NULL as @ctx. | |
d9edf92d DV |
321 | * |
322 | * When a die situation is indicated by returning -EDEADLK all locks held by | |
323 | * @ctx must be unlocked and then dma_resv_lock_slow_interruptible() called on | |
324 | * @obj. | |
325 | * | |
326 | * Unlocked by calling dma_resv_unlock(). | |
5d276a1a | 327 | */ |
52791eee CK |
328 | static inline int dma_resv_lock_interruptible(struct dma_resv *obj, |
329 | struct ww_acquire_ctx *ctx) | |
5d276a1a CK |
330 | { |
331 | return ww_mutex_lock_interruptible(&obj->lock, ctx); | |
332 | } | |
333 | ||
0dbd555a | 334 | /** |
52791eee | 335 | * dma_resv_lock_slow - slowpath lock the reservation object |
0dbd555a CK |
336 | * @obj: the reservation object |
337 | * @ctx: the locking context | |
338 | * | |
339 | * Acquires the reservation object after a die case. This function | |
52791eee | 340 | * will sleep until the lock becomes available. See dma_resv_lock() as |
0dbd555a | 341 | * well. |
d9edf92d DV |
342 | * |
343 | * See also dma_resv_lock_slow_interruptible() for the interruptible variant. | |
0dbd555a | 344 | */ |
52791eee CK |
345 | static inline void dma_resv_lock_slow(struct dma_resv *obj, |
346 | struct ww_acquire_ctx *ctx) | |
0dbd555a CK |
347 | { |
348 | ww_mutex_lock_slow(&obj->lock, ctx); | |
349 | } | |
350 | ||
351 | /** | |
52791eee | 352 | * dma_resv_lock_slow_interruptible - slowpath lock the reservation |
0dbd555a CK |
353 | * object, interruptible |
354 | * @obj: the reservation object | |
355 | * @ctx: the locking context | |
356 | * | |
357 | * Acquires the reservation object interruptible after a die case. This function | |
358 | * will sleep until the lock becomes available. See | |
52791eee | 359 | * dma_resv_lock_interruptible() as well. |
0dbd555a | 360 | */ |
52791eee CK |
361 | static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj, |
362 | struct ww_acquire_ctx *ctx) | |
0dbd555a CK |
363 | { |
364 | return ww_mutex_lock_slow_interruptible(&obj->lock, ctx); | |
365 | } | |
5d276a1a | 366 | |
2955b73d | 367 | /** |
52791eee | 368 | * dma_resv_trylock - trylock the reservation object |
2955b73d CW |
369 | * @obj: the reservation object |
370 | * | |
371 | * Tries to lock the reservation object for exclusive access and modification. | |
372 | * Note, that the lock is only against other writers, readers will run | |
373 | * concurrently with a writer under RCU. The seqlock is used to notify readers | |
374 | * if they overlap with a writer. | |
375 | * | |
376 | * Also note that since no context is provided, no deadlock protection is | |
d9edf92d | 377 | * possible, which is also not needed for a trylock. |
2955b73d CW |
378 | * |
379 | * Returns true if the lock was acquired, false otherwise. | |
380 | */ | |
52791eee | 381 | static inline bool __must_check dma_resv_trylock(struct dma_resv *obj) |
2955b73d | 382 | { |
12235da8 | 383 | return ww_mutex_trylock(&obj->lock, NULL); |
2955b73d CW |
384 | } |
385 | ||
0dbd555a | 386 | /** |
52791eee | 387 | * dma_resv_is_locked - is the reservation object locked |
0dbd555a CK |
388 | * @obj: the reservation object |
389 | * | |
390 | * Returns true if the mutex is locked, false if unlocked. | |
391 | */ | |
52791eee | 392 | static inline bool dma_resv_is_locked(struct dma_resv *obj) |
0dbd555a CK |
393 | { |
394 | return ww_mutex_is_locked(&obj->lock); | |
395 | } | |
396 | ||
397 | /** | |
52791eee | 398 | * dma_resv_locking_ctx - returns the context used to lock the object |
0dbd555a CK |
399 | * @obj: the reservation object |
400 | * | |
401 | * Returns the context used to lock a reservation object or NULL if no context | |
402 | * was used or the object is not locked at all. | |
d9edf92d DV |
403 | * |
404 | * WARNING: This interface is pretty horrible, but TTM needs it because it | |
405 | * doesn't pass the struct ww_acquire_ctx around in some very long callchains. | |
406 | * Everyone else just uses it to check whether they're holding a reservation or | |
407 | * not. | |
0dbd555a | 408 | */ |
52791eee | 409 | static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj) |
0dbd555a CK |
410 | { |
411 | return READ_ONCE(obj->lock.ctx); | |
412 | } | |
413 | ||
122020af | 414 | /** |
52791eee | 415 | * dma_resv_unlock - unlock the reservation object |
122020af CW |
416 | * @obj: the reservation object |
417 | * | |
418 | * Unlocks the reservation object following exclusive access. | |
419 | */ | |
52791eee | 420 | static inline void dma_resv_unlock(struct dma_resv *obj) |
122020af | 421 | { |
0c6b522a | 422 | dma_resv_reset_shared_max(obj); |
122020af CW |
423 | ww_mutex_unlock(&obj->lock); |
424 | } | |
425 | ||
b016cd6e | 426 | /** |
82c850c1 | 427 | * dma_resv_excl_fence - return the object's exclusive fence |
b016cd6e CW |
428 | * @obj: the reservation object |
429 | * | |
6edbd6ab CK |
430 | * Returns the exclusive fence (if any). Caller must either hold the objects |
431 | * through dma_resv_lock() or the RCU read side lock through rcu_read_lock(), | |
432 | * or one of the variants of each | |
b016cd6e CW |
433 | * |
434 | * RETURNS | |
435 | * The exclusive fence or NULL | |
436 | */ | |
437 | static inline struct dma_fence * | |
6edbd6ab | 438 | dma_resv_excl_fence(struct dma_resv *obj) |
b016cd6e | 439 | { |
6edbd6ab | 440 | return rcu_dereference_check(obj->fence_excl, dma_resv_held(obj)); |
b016cd6e CW |
441 | } |
442 | ||
fb5ce730 CK |
443 | /** |
444 | * dma_resv_shared_list - get the reservation object's shared fence list | |
445 | * @obj: the reservation object | |
446 | * | |
447 | * Returns the shared fence list. Caller must either hold the objects | |
448 | * through dma_resv_lock() or the RCU read side lock through rcu_read_lock(), | |
449 | * or one of the variants of each | |
450 | */ | |
451 | static inline struct dma_resv_list *dma_resv_shared_list(struct dma_resv *obj) | |
452 | { | |
453 | return rcu_dereference_check(obj->fence, dma_resv_held(obj)); | |
454 | } | |
455 | ||
52791eee CK |
456 | void dma_resv_init(struct dma_resv *obj); |
457 | void dma_resv_fini(struct dma_resv *obj); | |
458 | int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences); | |
459 | void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence); | |
52791eee | 460 | void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence); |
d3fae3b3 CK |
461 | int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl, |
462 | unsigned *pshared_count, struct dma_fence ***pshared); | |
52791eee | 463 | int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src); |
d3fae3b3 CK |
464 | long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr, |
465 | unsigned long timeout); | |
466 | bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all); | |
a25efb38 | 467 | void dma_resv_describe(struct dma_resv *obj, struct seq_file *seq); |
3c3b177a | 468 | |
786d7257 | 469 | #endif /* _LINUX_RESERVATION_H */ |