1 /* 1 /*
2 * Header file for reservations for dma-buf an 2 * Header file for reservations for dma-buf and ttm
3 * 3 *
4 * Copyright(C) 2011 Linaro Limited. All right 4 * Copyright(C) 2011 Linaro Limited. All rights reserved.
5 * Copyright (C) 2012-2013 Canonical Ltd 5 * Copyright (C) 2012-2013 Canonical Ltd
6 * Copyright (C) 2012 Texas Instruments 6 * Copyright (C) 2012 Texas Instruments
7 * 7 *
8 * Authors: 8 * Authors:
9 * Rob Clark <robdclark@gmail.com> 9 * Rob Clark <robdclark@gmail.com>
10 * Maarten Lankhorst <maarten.lankhorst@canoni 10 * Maarten Lankhorst <maarten.lankhorst@canonical.com>
11 * Thomas Hellstrom <thellstrom-at-vmware-dot- 11 * Thomas Hellstrom <thellstrom-at-vmware-dot-com>
12 * 12 *
13 * Based on bo.c which bears the following cop 13 * Based on bo.c which bears the following copyright notice,
14 * but is dual licensed: 14 * but is dual licensed:
15 * 15 *
16 * Copyright (c) 2006-2009 VMware, Inc., Palo 16 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
17 * All Rights Reserved. 17 * All Rights Reserved.
18 * 18 *
19 * Permission is hereby granted, free of charg 19 * Permission is hereby granted, free of charge, to any person obtaining a
20 * copy of this software and associated docume 20 * copy of this software and associated documentation files (the
21 * "Software"), to deal in the Software withou 21 * "Software"), to deal in the Software without restriction, including
22 * without limitation the rights to use, copy, 22 * without limitation the rights to use, copy, modify, merge, publish,
23 * distribute, sub license, and/or sell copies 23 * distribute, sub license, and/or sell copies of the Software, and to
24 * permit persons to whom the Software is furn 24 * permit persons to whom the Software is furnished to do so, subject to
25 * the following conditions: 25 * the following conditions:
26 * 26 *
27 * The above copyright notice and this permiss 27 * The above copyright notice and this permission notice (including the
28 * next paragraph) shall be included in all co 28 * next paragraph) shall be included in all copies or substantial portions
29 * of the Software. 29 * of the Software.
30 * 30 *
31 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT W 31 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
32 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE W 32 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
33 * FITNESS FOR A PARTICULAR PURPOSE AND NON-IN 33 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
34 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS S 34 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
35 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN A 35 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
36 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNE 36 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
37 * USE OR OTHER DEALINGS IN THE SOFTWARE. 37 * USE OR OTHER DEALINGS IN THE SOFTWARE.
38 */ 38 */
39 #ifndef _LINUX_RESERVATION_H 39 #ifndef _LINUX_RESERVATION_H
40 #define _LINUX_RESERVATION_H 40 #define _LINUX_RESERVATION_H
41 41
42 #include <linux/ww_mutex.h> 42 #include <linux/ww_mutex.h>
43 #include <linux/dma-fence.h> 43 #include <linux/dma-fence.h>
44 #include <linux/slab.h> 44 #include <linux/slab.h>
45 #include <linux/seqlock.h> 45 #include <linux/seqlock.h>
46 #include <linux/rcupdate.h> 46 #include <linux/rcupdate.h>
47 47
48 extern struct ww_class reservation_ww_class; 48 extern struct ww_class reservation_ww_class;
49 49
50 struct dma_resv_list; <<
51 <<
52 /** 50 /**
53 * enum dma_resv_usage - how the fences from a !! 51 * struct dma_resv_list - a list of shared fences
54 * !! 52 * @rcu: for internal use
55 * This enum describes the different use cases !! 53 * @shared_count: table of shared fences
56 * controls which fences are returned when que !! 54 * @shared_max: for growing shared fence table
57 * !! 55 * @shared: shared fence table
58 * An important fact is that there is the orde !! 56 */
59 * when the dma_resv object is asked for fence !! 57 struct dma_resv_list {
60 * for the lower use case are returned as well !! 58 struct rcu_head rcu;
61 * !! 59 u32 shared_count, shared_max;
62 * For example when asking for WRITE fences th !! 60 struct dma_fence __rcu *shared[];
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 }; 61 };
118 62
119 /** 63 /**
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 64 * struct dma_resv - a reservation object manages fences for a buffer
140 * 65 *
141 * This is a container for dma_fence objects w !! 66 * There are multiple uses for this, with sometimes slightly different rules in
142 * cases. !! 67 * how the fence slots are used.
143 * 68 *
144 * One use is to synchronize cross-driver acce 69 * One use is to synchronize cross-driver access to a struct dma_buf, either for
145 * dynamic buffer management or just to handle 70 * dynamic buffer management or just to handle implicit synchronization between
146 * different users of the buffer in userspace. 71 * different users of the buffer in userspace. See &dma_buf.resv for a more
147 * in-depth discussion. 72 * in-depth discussion.
148 * 73 *
149 * The other major use is to manage access and 74 * The other major use is to manage access and locking within a driver in a
150 * buffer based memory manager. struct ttm_buf 75 * buffer based memory manager. struct ttm_buffer_object is the canonical
151 * example here, since this is where reservati 76 * example here, since this is where reservation objects originated from. But
152 * use in drivers is spreading and some driver 77 * use in drivers is spreading and some drivers also manage struct
153 * drm_gem_object with the same scheme. 78 * drm_gem_object with the same scheme.
154 */ 79 */
155 struct dma_resv { 80 struct dma_resv {
156 /** 81 /**
157 * @lock: 82 * @lock:
158 * 83 *
159 * Update side lock. Don't use directl 84 * Update side lock. Don't use directly, instead use the wrapper
160 * functions like dma_resv_lock() and 85 * functions like dma_resv_lock() and dma_resv_unlock().
161 * 86 *
162 * Drivers which use the reservation o 87 * Drivers which use the reservation object to manage memory dynamically
163 * also use this lock to protect buffe 88 * also use this lock to protect buffer object state like placement,
164 * allocation policies or throughout c 89 * allocation policies or throughout command submission.
165 */ 90 */
166 struct ww_mutex lock; 91 struct ww_mutex lock;
167 92
168 /** 93 /**
169 * @fences: !! 94 * @seq:
170 * 95 *
171 * Array of fences which where added t !! 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 */
>> 100 seqcount_ww_mutex_t seq;
>> 101
>> 102 /**
>> 103 * @fence_excl:
>> 104 *
>> 105 * The exclusive fence, if there is one currently.
172 * 106 *
173 * A new fence is added by calling dma !! 107 * There are two ways to update this fence:
174 * often needs to be done past the poi !! 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 */
>> 129 struct dma_fence __rcu *fence_excl;
>> 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
175 * submission it cannot fail, and ther 142 * submission it cannot fail, and therefore sufficient slots need to be
176 * reserved by calling dma_resv_reserv !! 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.
177 */ 148 */
178 struct dma_resv_list __rcu *fences; !! 149 struct dma_resv_list __rcu *fence;
179 }; 150 };
180 151
181 /** 152 /**
182 * struct dma_resv_iter - current position int 153 * struct dma_resv_iter - current position into the dma_resv fences
183 * 154 *
184 * Don't touch this directly in the driver, us 155 * Don't touch this directly in the driver, use the accessor function instead.
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 */ 156 */
193 struct dma_resv_iter { 157 struct dma_resv_iter {
194 /** @obj: The dma_resv object we itera 158 /** @obj: The dma_resv object we iterate over */
195 struct dma_resv *obj; 159 struct dma_resv *obj;
196 160
197 /** @usage: Return fences with this us !! 161 /** @all_fences: If all fences should be returned */
198 enum dma_resv_usage usage; !! 162 bool all_fences;
199 163
200 /** @fence: the currently handled fenc 164 /** @fence: the currently handled fence */
201 struct dma_fence *fence; 165 struct dma_fence *fence;
202 166
203 /** @fence_usage: the usage of the cur !! 167 /** @seq: sequence number to check for modifications */
204 enum dma_resv_usage fence_usage; !! 168 unsigned int seq;
205 169
206 /** @index: index into the shared fenc 170 /** @index: index into the shared fences */
207 unsigned int index; 171 unsigned int index;
208 172
209 /** @fences: the shared fences; privat 173 /** @fences: the shared fences; private, *MUST* not dereference */
210 struct dma_resv_list *fences; 174 struct dma_resv_list *fences;
211 175
212 /** @num_fences: number of fences */ !! 176 /** @shared_count: number of shared fences */
213 unsigned int num_fences; !! 177 unsigned int shared_count;
214 178
215 /** @is_restarted: true if this is the 179 /** @is_restarted: true if this is the first returned fence */
216 bool is_restarted; 180 bool is_restarted;
217 }; 181 };
218 182
219 struct dma_fence *dma_resv_iter_first_unlocked 183 struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor);
220 struct dma_fence *dma_resv_iter_next_unlocked( 184 struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor);
221 struct dma_fence *dma_resv_iter_first(struct d 185 struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor);
222 struct dma_fence *dma_resv_iter_next(struct dm 186 struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor);
223 187
224 /** 188 /**
225 * dma_resv_iter_begin - initialize a dma_resv 189 * dma_resv_iter_begin - initialize a dma_resv_iter object
226 * @cursor: The dma_resv_iter object to initia 190 * @cursor: The dma_resv_iter object to initialize
227 * @obj: The dma_resv object which we want to 191 * @obj: The dma_resv object which we want to iterate over
228 * @usage: controls which fences to include, s !! 192 * @all_fences: If all fences should be returned or just the exclusive one
229 */ 193 */
230 static inline void dma_resv_iter_begin(struct 194 static inline void dma_resv_iter_begin(struct dma_resv_iter *cursor,
231 struct 195 struct dma_resv *obj,
232 enum dm !! 196 bool all_fences)
233 { 197 {
234 cursor->obj = obj; 198 cursor->obj = obj;
235 cursor->usage = usage; !! 199 cursor->all_fences = all_fences;
236 cursor->fence = NULL; 200 cursor->fence = NULL;
237 } 201 }
238 202
239 /** 203 /**
240 * dma_resv_iter_end - cleanup a dma_resv_iter 204 * dma_resv_iter_end - cleanup a dma_resv_iter object
241 * @cursor: the dma_resv_iter object which sho 205 * @cursor: the dma_resv_iter object which should be cleaned up
242 * 206 *
243 * Make sure that the reference to the fence i 207 * Make sure that the reference to the fence in the cursor is properly
244 * dropped. 208 * dropped.
245 */ 209 */
246 static inline void dma_resv_iter_end(struct dm 210 static inline void dma_resv_iter_end(struct dma_resv_iter *cursor)
247 { 211 {
248 dma_fence_put(cursor->fence); 212 dma_fence_put(cursor->fence);
249 } 213 }
250 214
251 /** 215 /**
252 * dma_resv_iter_usage - Return the usage of t !! 216 * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
253 * @cursor: the cursor of the current position 217 * @cursor: the cursor of the current position
254 * 218 *
255 * Returns the usage of the currently processe !! 219 * Returns true if the currently returned fence is the exclusive one.
256 */ 220 */
257 static inline enum dma_resv_usage !! 221 static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
258 dma_resv_iter_usage(struct dma_resv_iter *curs <<
259 { 222 {
260 return cursor->fence_usage; !! 223 return cursor->index == 0;
261 } 224 }
262 225
263 /** 226 /**
264 * dma_resv_iter_is_restarted - test if this i 227 * dma_resv_iter_is_restarted - test if this is the first fence after a restart
265 * @cursor: the cursor with the current positi 228 * @cursor: the cursor with the current position
266 * 229 *
267 * Return true if this is the first fence in a 230 * Return true if this is the first fence in an iteration after a restart.
268 */ 231 */
269 static inline bool dma_resv_iter_is_restarted( 232 static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
270 { 233 {
271 return cursor->is_restarted; 234 return cursor->is_restarted;
272 } 235 }
273 236
274 /** 237 /**
275 * dma_resv_for_each_fence_unlocked - unlocked 238 * dma_resv_for_each_fence_unlocked - unlocked fence iterator
276 * @cursor: a struct dma_resv_iter pointer 239 * @cursor: a struct dma_resv_iter pointer
277 * @fence: the current fence 240 * @fence: the current fence
278 * 241 *
279 * Iterate over the fences in a struct dma_res 242 * Iterate over the fences in a struct dma_resv object without holding the
280 * &dma_resv.lock and using RCU instead. The c 243 * &dma_resv.lock and using RCU instead. The cursor needs to be initialized
281 * with dma_resv_iter_begin() and cleaned up w 244 * with dma_resv_iter_begin() and cleaned up with dma_resv_iter_end(). Inside
282 * the iterator a reference to the dma_fence i 245 * the iterator a reference to the dma_fence is held and the RCU lock dropped.
283 * !! 246 * When the dma_resv is modified the iteration starts over again.
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 */ 247 */
289 #define dma_resv_for_each_fence_unlocked(curso 248 #define dma_resv_for_each_fence_unlocked(cursor, fence) \
290 for (fence = dma_resv_iter_first_unloc 249 for (fence = dma_resv_iter_first_unlocked(cursor); \
291 fence; fence = dma_resv_iter_next 250 fence; fence = dma_resv_iter_next_unlocked(cursor))
292 251
293 /** 252 /**
294 * dma_resv_for_each_fence - fence iterator 253 * dma_resv_for_each_fence - fence iterator
295 * @cursor: a struct dma_resv_iter pointer 254 * @cursor: a struct dma_resv_iter pointer
296 * @obj: a dma_resv object pointer 255 * @obj: a dma_resv object pointer
297 * @usage: controls which fences to return !! 256 * @all_fences: true if all fences should be returned
298 * @fence: the current fence 257 * @fence: the current fence
299 * 258 *
300 * Iterate over the fences in a struct dma_res 259 * Iterate over the fences in a struct dma_resv object while holding the
301 * &dma_resv.lock. @all_fences controls if the 260 * &dma_resv.lock. @all_fences controls if the shared fences are returned as
302 * well. The cursor initialisation is part of 261 * well. The cursor initialisation is part of the iterator and the fence stays
303 * valid as long as the lock is held and so no 262 * valid as long as the lock is held and so no extra reference to the fence is
304 * taken. 263 * taken.
305 */ 264 */
306 #define dma_resv_for_each_fence(cursor, obj, u !! 265 #define dma_resv_for_each_fence(cursor, obj, all_fences, fence) \
307 for (dma_resv_iter_begin(cursor, obj, !! 266 for (dma_resv_iter_begin(cursor, obj, all_fences), \
308 fence = dma_resv_iter_first(curso 267 fence = dma_resv_iter_first(cursor); fence; \
309 fence = dma_resv_iter_next(cursor 268 fence = dma_resv_iter_next(cursor))
310 269
311 #define dma_resv_held(obj) lockdep_is_held(&(o 270 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
312 #define dma_resv_assert_held(obj) lockdep_asse 271 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
313 272
314 #ifdef CONFIG_DEBUG_MUTEXES 273 #ifdef CONFIG_DEBUG_MUTEXES
315 void dma_resv_reset_max_fences(struct dma_resv !! 274 void dma_resv_reset_shared_max(struct dma_resv *obj);
316 #else 275 #else
317 static inline void dma_resv_reset_max_fences(s !! 276 static inline void dma_resv_reset_shared_max(struct dma_resv *obj) {}
318 #endif 277 #endif
319 278
320 /** 279 /**
321 * dma_resv_lock - lock the reservation object 280 * dma_resv_lock - lock the reservation object
322 * @obj: the reservation object 281 * @obj: the reservation object
323 * @ctx: the locking context 282 * @ctx: the locking context
324 * 283 *
325 * Locks the reservation object for exclusive 284 * Locks the reservation object for exclusive access and modification. Note,
326 * that the lock is only against other writers 285 * that the lock is only against other writers, readers will run concurrently
327 * with a writer under RCU. The seqlock is use 286 * with a writer under RCU. The seqlock is used to notify readers if they
328 * overlap with a writer. 287 * overlap with a writer.
329 * 288 *
330 * As the reservation object may be locked by 289 * As the reservation object may be locked by multiple parties in an
331 * undefined order, a #ww_acquire_ctx is passe 290 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
332 * is detected. See ww_mutex_lock() and ww_acq 291 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
333 * object may be locked by itself by passing N 292 * object may be locked by itself by passing NULL as @ctx.
334 * 293 *
335 * When a die situation is indicated by return 294 * When a die situation is indicated by returning -EDEADLK all locks held by
336 * @ctx must be unlocked and then dma_resv_loc 295 * @ctx must be unlocked and then dma_resv_lock_slow() called on @obj.
337 * 296 *
338 * Unlocked by calling dma_resv_unlock(). 297 * Unlocked by calling dma_resv_unlock().
339 * 298 *
340 * See also dma_resv_lock_interruptible() for 299 * See also dma_resv_lock_interruptible() for the interruptible variant.
341 */ 300 */
342 static inline int dma_resv_lock(struct dma_res 301 static inline int dma_resv_lock(struct dma_resv *obj,
343 struct ww_acqu 302 struct ww_acquire_ctx *ctx)
344 { 303 {
345 return ww_mutex_lock(&obj->lock, ctx); 304 return ww_mutex_lock(&obj->lock, ctx);
346 } 305 }
347 306
348 /** 307 /**
349 * dma_resv_lock_interruptible - lock the rese 308 * dma_resv_lock_interruptible - lock the reservation object
350 * @obj: the reservation object 309 * @obj: the reservation object
351 * @ctx: the locking context 310 * @ctx: the locking context
352 * 311 *
353 * Locks the reservation object interruptible 312 * Locks the reservation object interruptible for exclusive access and
354 * modification. Note, that the lock is only a 313 * modification. Note, that the lock is only against other writers, readers
355 * will run concurrently with a writer under R 314 * will run concurrently with a writer under RCU. The seqlock is used to
356 * notify readers if they overlap with a write 315 * notify readers if they overlap with a writer.
357 * 316 *
358 * As the reservation object may be locked by 317 * As the reservation object may be locked by multiple parties in an
359 * undefined order, a #ww_acquire_ctx is passe 318 * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
360 * is detected. See ww_mutex_lock() and ww_acq 319 * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
361 * object may be locked by itself by passing N 320 * object may be locked by itself by passing NULL as @ctx.
362 * 321 *
363 * When a die situation is indicated by return 322 * When a die situation is indicated by returning -EDEADLK all locks held by
364 * @ctx must be unlocked and then dma_resv_loc 323 * @ctx must be unlocked and then dma_resv_lock_slow_interruptible() called on
365 * @obj. 324 * @obj.
366 * 325 *
367 * Unlocked by calling dma_resv_unlock(). 326 * Unlocked by calling dma_resv_unlock().
368 */ 327 */
369 static inline int dma_resv_lock_interruptible( 328 static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
370 329 struct ww_acquire_ctx *ctx)
371 { 330 {
372 return ww_mutex_lock_interruptible(&ob 331 return ww_mutex_lock_interruptible(&obj->lock, ctx);
373 } 332 }
374 333
375 /** 334 /**
376 * dma_resv_lock_slow - slowpath lock the rese 335 * dma_resv_lock_slow - slowpath lock the reservation object
377 * @obj: the reservation object 336 * @obj: the reservation object
378 * @ctx: the locking context 337 * @ctx: the locking context
379 * 338 *
380 * Acquires the reservation object after a die 339 * Acquires the reservation object after a die case. This function
381 * will sleep until the lock becomes available 340 * will sleep until the lock becomes available. See dma_resv_lock() as
382 * well. 341 * well.
383 * 342 *
384 * See also dma_resv_lock_slow_interruptible() 343 * See also dma_resv_lock_slow_interruptible() for the interruptible variant.
385 */ 344 */
386 static inline void dma_resv_lock_slow(struct d 345 static inline void dma_resv_lock_slow(struct dma_resv *obj,
387 struct w 346 struct ww_acquire_ctx *ctx)
388 { 347 {
389 ww_mutex_lock_slow(&obj->lock, ctx); 348 ww_mutex_lock_slow(&obj->lock, ctx);
390 } 349 }
391 350
392 /** 351 /**
393 * dma_resv_lock_slow_interruptible - slowpath 352 * dma_resv_lock_slow_interruptible - slowpath lock the reservation
394 * object, interruptible 353 * object, interruptible
395 * @obj: the reservation object 354 * @obj: the reservation object
396 * @ctx: the locking context 355 * @ctx: the locking context
397 * 356 *
398 * Acquires the reservation object interruptib 357 * Acquires the reservation object interruptible after a die case. This function
399 * will sleep until the lock becomes available 358 * will sleep until the lock becomes available. See
400 * dma_resv_lock_interruptible() as well. 359 * dma_resv_lock_interruptible() as well.
401 */ 360 */
402 static inline int dma_resv_lock_slow_interrupt 361 static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
403 362 struct ww_acquire_ctx *ctx)
404 { 363 {
405 return ww_mutex_lock_slow_interruptibl 364 return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
406 } 365 }
407 366
408 /** 367 /**
409 * dma_resv_trylock - trylock the reservation 368 * dma_resv_trylock - trylock the reservation object
410 * @obj: the reservation object 369 * @obj: the reservation object
411 * 370 *
412 * Tries to lock the reservation object for ex 371 * Tries to lock the reservation object for exclusive access and modification.
413 * Note, that the lock is only against other w 372 * Note, that the lock is only against other writers, readers will run
414 * concurrently with a writer under RCU. The s 373 * concurrently with a writer under RCU. The seqlock is used to notify readers
415 * if they overlap with a writer. 374 * if they overlap with a writer.
416 * 375 *
417 * Also note that since no context is provided 376 * Also note that since no context is provided, no deadlock protection is
418 * possible, which is also not needed for a tr 377 * possible, which is also not needed for a trylock.
419 * 378 *
420 * Returns true if the lock was acquired, fals 379 * Returns true if the lock was acquired, false otherwise.
421 */ 380 */
422 static inline bool __must_check dma_resv_trylo 381 static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
423 { 382 {
424 return ww_mutex_trylock(&obj->lock, NU 383 return ww_mutex_trylock(&obj->lock, NULL);
425 } 384 }
426 385
427 /** 386 /**
428 * dma_resv_is_locked - is the reservation obj 387 * dma_resv_is_locked - is the reservation object locked
429 * @obj: the reservation object 388 * @obj: the reservation object
430 * 389 *
431 * Returns true if the mutex is locked, false 390 * Returns true if the mutex is locked, false if unlocked.
432 */ 391 */
433 static inline bool dma_resv_is_locked(struct d 392 static inline bool dma_resv_is_locked(struct dma_resv *obj)
434 { 393 {
435 return ww_mutex_is_locked(&obj->lock); 394 return ww_mutex_is_locked(&obj->lock);
436 } 395 }
437 396
438 /** 397 /**
439 * dma_resv_locking_ctx - returns the context 398 * dma_resv_locking_ctx - returns the context used to lock the object
440 * @obj: the reservation object 399 * @obj: the reservation object
441 * 400 *
442 * Returns the context used to lock a reservat 401 * Returns the context used to lock a reservation object or NULL if no context
443 * was used or the object is not locked at all 402 * was used or the object is not locked at all.
444 * 403 *
445 * WARNING: This interface is pretty horrible, 404 * WARNING: This interface is pretty horrible, but TTM needs it because it
446 * doesn't pass the struct ww_acquire_ctx arou 405 * doesn't pass the struct ww_acquire_ctx around in some very long callchains.
447 * Everyone else just uses it to check whether 406 * Everyone else just uses it to check whether they're holding a reservation or
448 * not. 407 * not.
449 */ 408 */
450 static inline struct ww_acquire_ctx *dma_resv_ 409 static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
451 { 410 {
452 return READ_ONCE(obj->lock.ctx); 411 return READ_ONCE(obj->lock.ctx);
453 } 412 }
454 413
455 /** 414 /**
456 * dma_resv_unlock - unlock the reservation ob 415 * dma_resv_unlock - unlock the reservation object
457 * @obj: the reservation object 416 * @obj: the reservation object
458 * 417 *
459 * Unlocks the reservation object following ex 418 * Unlocks the reservation object following exclusive access.
460 */ 419 */
461 static inline void dma_resv_unlock(struct dma_ 420 static inline void dma_resv_unlock(struct dma_resv *obj)
462 { 421 {
463 dma_resv_reset_max_fences(obj); !! 422 dma_resv_reset_shared_max(obj);
464 ww_mutex_unlock(&obj->lock); 423 ww_mutex_unlock(&obj->lock);
465 } 424 }
466 425
>> 426 /**
>> 427 * dma_resv_excl_fence - return the object's exclusive fence
>> 428 * @obj: the reservation object
>> 429 *
>> 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
>> 433 *
>> 434 * RETURNS
>> 435 * The exclusive fence or NULL
>> 436 */
>> 437 static inline struct dma_fence *
>> 438 dma_resv_excl_fence(struct dma_resv *obj)
>> 439 {
>> 440 return rcu_dereference_check(obj->fence_excl, dma_resv_held(obj));
>> 441 }
>> 442
>> 443 /**
>> 444 * dma_resv_get_excl_unlocked - get the reservation object's
>> 445 * exclusive fence, without lock held.
>> 446 * @obj: the reservation object
>> 447 *
>> 448 * If there is an exclusive fence, this atomically increments it's
>> 449 * reference count and returns it.
>> 450 *
>> 451 * RETURNS
>> 452 * The exclusive fence or NULL if none
>> 453 */
>> 454 static inline struct dma_fence *
>> 455 dma_resv_get_excl_unlocked(struct dma_resv *obj)
>> 456 {
>> 457 struct dma_fence *fence;
>> 458
>> 459 if (!rcu_access_pointer(obj->fence_excl))
>> 460 return NULL;
>> 461
>> 462 rcu_read_lock();
>> 463 fence = dma_fence_get_rcu_safe(&obj->fence_excl);
>> 464 rcu_read_unlock();
>> 465
>> 466 return fence;
>> 467 }
>> 468
>> 469 /**
>> 470 * dma_resv_shared_list - get the reservation object's shared fence list
>> 471 * @obj: the reservation object
>> 472 *
>> 473 * Returns the shared fence list. Caller must either hold the objects
>> 474 * through dma_resv_lock() or the RCU read side lock through rcu_read_lock(),
>> 475 * or one of the variants of each
>> 476 */
>> 477 static inline struct dma_resv_list *dma_resv_shared_list(struct dma_resv *obj)
>> 478 {
>> 479 return rcu_dereference_check(obj->fence, dma_resv_held(obj));
>> 480 }
>> 481
467 void dma_resv_init(struct dma_resv *obj); 482 void dma_resv_init(struct dma_resv *obj);
468 void dma_resv_fini(struct dma_resv *obj); 483 void dma_resv_fini(struct dma_resv *obj);
469 int dma_resv_reserve_fences(struct dma_resv *o !! 484 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
470 void dma_resv_add_fence(struct dma_resv *obj, !! 485 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
471 enum dma_resv_usage us !! 486 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
472 void dma_resv_replace_fences(struct dma_resv * !! 487 int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
473 struct dma_fence !! 488 unsigned *pshared_count, struct dma_fence ***pshared);
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, 489 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
480 long dma_resv_wait_timeout(struct dma_resv *ob !! 490 long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
481 bool intr, unsigned !! 491 unsigned long timeout);
482 void dma_resv_set_deadline(struct dma_resv *ob !! 492 bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all);
483 ktime_t deadline); <<
484 bool dma_resv_test_signaled(struct dma_resv *o <<
485 void dma_resv_describe(struct dma_resv *obj, s <<
486 493
487 #endif /* _LINUX_RESERVATION_H */ 494 #endif /* _LINUX_RESERVATION_H */
488 495
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