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e941759c ML |
1 | /* |
2 | * Fence mechanism for dma-buf and to allow for asynchronous dma access | |
3 | * | |
4 | * Copyright (C) 2012 Canonical Ltd | |
5 | * Copyright (C) 2012 Texas Instruments | |
6 | * | |
7 | * Authors: | |
8 | * Rob Clark <robdclark@gmail.com> | |
9 | * Maarten Lankhorst <maarten.lankhorst@canonical.com> | |
10 | * | |
11 | * This program is free software; you can redistribute it and/or modify it | |
12 | * under the terms of the GNU General Public License version 2 as published by | |
13 | * the Free Software Foundation. | |
14 | * | |
15 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
16 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
17 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
18 | * more details. | |
19 | */ | |
20 | ||
21 | #include <linux/slab.h> | |
22 | #include <linux/export.h> | |
23 | #include <linux/atomic.h> | |
24 | #include <linux/fence.h> | |
25 | ||
26 | #define CREATE_TRACE_POINTS | |
27 | #include <trace/events/fence.h> | |
28 | ||
29 | EXPORT_TRACEPOINT_SYMBOL(fence_annotate_wait_on); | |
30 | EXPORT_TRACEPOINT_SYMBOL(fence_emit); | |
31 | ||
e9f3b796 | 32 | /* |
e941759c ML |
33 | * fence context counter: each execution context should have its own |
34 | * fence context, this allows checking if fences belong to the same | |
35 | * context or not. One device can have multiple separate contexts, | |
36 | * and they're used if some engine can run independently of another. | |
37 | */ | |
76bf0db5 | 38 | static atomic64_t fence_context_counter = ATOMIC64_INIT(0); |
e941759c ML |
39 | |
40 | /** | |
41 | * fence_context_alloc - allocate an array of fence contexts | |
42 | * @num: [in] amount of contexts to allocate | |
43 | * | |
44 | * This function will return the first index of the number of fences allocated. | |
45 | * The fence context is used for setting fence->context to a unique number. | |
46 | */ | |
76bf0db5 | 47 | u64 fence_context_alloc(unsigned num) |
e941759c ML |
48 | { |
49 | BUG_ON(!num); | |
76bf0db5 | 50 | return atomic64_add_return(num, &fence_context_counter) - num; |
e941759c ML |
51 | } |
52 | EXPORT_SYMBOL(fence_context_alloc); | |
53 | ||
54 | /** | |
55 | * fence_signal_locked - signal completion of a fence | |
56 | * @fence: the fence to signal | |
57 | * | |
58 | * Signal completion for software callbacks on a fence, this will unblock | |
59 | * fence_wait() calls and run all the callbacks added with | |
60 | * fence_add_callback(). Can be called multiple times, but since a fence | |
61 | * can only go from unsignaled to signaled state, it will only be effective | |
62 | * the first time. | |
63 | * | |
64 | * Unlike fence_signal, this function must be called with fence->lock held. | |
65 | */ | |
66 | int fence_signal_locked(struct fence *fence) | |
67 | { | |
68 | struct fence_cb *cur, *tmp; | |
69 | int ret = 0; | |
70 | ||
78010cd9 RC |
71 | lockdep_assert_held(fence->lock); |
72 | ||
e941759c ML |
73 | if (WARN_ON(!fence)) |
74 | return -EINVAL; | |
75 | ||
76 | if (!ktime_to_ns(fence->timestamp)) { | |
77 | fence->timestamp = ktime_get(); | |
78 | smp_mb__before_atomic(); | |
79 | } | |
80 | ||
81 | if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { | |
82 | ret = -EINVAL; | |
83 | ||
84 | /* | |
85 | * we might have raced with the unlocked fence_signal, | |
86 | * still run through all callbacks | |
87 | */ | |
88 | } else | |
89 | trace_fence_signaled(fence); | |
90 | ||
91 | list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { | |
92 | list_del_init(&cur->node); | |
93 | cur->func(fence, cur); | |
94 | } | |
95 | return ret; | |
96 | } | |
97 | EXPORT_SYMBOL(fence_signal_locked); | |
98 | ||
99 | /** | |
100 | * fence_signal - signal completion of a fence | |
101 | * @fence: the fence to signal | |
102 | * | |
103 | * Signal completion for software callbacks on a fence, this will unblock | |
104 | * fence_wait() calls and run all the callbacks added with | |
105 | * fence_add_callback(). Can be called multiple times, but since a fence | |
106 | * can only go from unsignaled to signaled state, it will only be effective | |
107 | * the first time. | |
108 | */ | |
109 | int fence_signal(struct fence *fence) | |
110 | { | |
111 | unsigned long flags; | |
112 | ||
113 | if (!fence) | |
114 | return -EINVAL; | |
115 | ||
116 | if (!ktime_to_ns(fence->timestamp)) { | |
117 | fence->timestamp = ktime_get(); | |
118 | smp_mb__before_atomic(); | |
119 | } | |
120 | ||
121 | if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
122 | return -EINVAL; | |
123 | ||
124 | trace_fence_signaled(fence); | |
125 | ||
126 | if (test_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) { | |
127 | struct fence_cb *cur, *tmp; | |
128 | ||
129 | spin_lock_irqsave(fence->lock, flags); | |
130 | list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { | |
131 | list_del_init(&cur->node); | |
132 | cur->func(fence, cur); | |
133 | } | |
134 | spin_unlock_irqrestore(fence->lock, flags); | |
135 | } | |
136 | return 0; | |
137 | } | |
138 | EXPORT_SYMBOL(fence_signal); | |
139 | ||
140 | /** | |
141 | * fence_wait_timeout - sleep until the fence gets signaled | |
142 | * or until timeout elapses | |
143 | * @fence: [in] the fence to wait on | |
144 | * @intr: [in] if true, do an interruptible wait | |
145 | * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT | |
146 | * | |
147 | * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the | |
148 | * remaining timeout in jiffies on success. Other error values may be | |
149 | * returned on custom implementations. | |
150 | * | |
151 | * Performs a synchronous wait on this fence. It is assumed the caller | |
152 | * directly or indirectly (buf-mgr between reservation and committing) | |
153 | * holds a reference to the fence, otherwise the fence might be | |
154 | * freed before return, resulting in undefined behavior. | |
155 | */ | |
156 | signed long | |
157 | fence_wait_timeout(struct fence *fence, bool intr, signed long timeout) | |
158 | { | |
159 | signed long ret; | |
160 | ||
161 | if (WARN_ON(timeout < 0)) | |
162 | return -EINVAL; | |
163 | ||
847b19a3 JZ |
164 | if (timeout == 0) |
165 | return fence_is_signaled(fence); | |
166 | ||
e941759c ML |
167 | trace_fence_wait_start(fence); |
168 | ret = fence->ops->wait(fence, intr, timeout); | |
169 | trace_fence_wait_end(fence); | |
170 | return ret; | |
171 | } | |
172 | EXPORT_SYMBOL(fence_wait_timeout); | |
173 | ||
174 | void fence_release(struct kref *kref) | |
175 | { | |
176 | struct fence *fence = | |
177 | container_of(kref, struct fence, refcount); | |
178 | ||
179 | trace_fence_destroy(fence); | |
180 | ||
181 | BUG_ON(!list_empty(&fence->cb_list)); | |
182 | ||
183 | if (fence->ops->release) | |
184 | fence->ops->release(fence); | |
185 | else | |
186 | fence_free(fence); | |
187 | } | |
188 | EXPORT_SYMBOL(fence_release); | |
189 | ||
190 | void fence_free(struct fence *fence) | |
191 | { | |
3c3b177a | 192 | kfree_rcu(fence, rcu); |
e941759c ML |
193 | } |
194 | EXPORT_SYMBOL(fence_free); | |
195 | ||
196 | /** | |
197 | * fence_enable_sw_signaling - enable signaling on fence | |
198 | * @fence: [in] the fence to enable | |
199 | * | |
200 | * this will request for sw signaling to be enabled, to make the fence | |
201 | * complete as soon as possible | |
202 | */ | |
203 | void fence_enable_sw_signaling(struct fence *fence) | |
204 | { | |
205 | unsigned long flags; | |
206 | ||
207 | if (!test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags) && | |
208 | !test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { | |
209 | trace_fence_enable_signal(fence); | |
210 | ||
211 | spin_lock_irqsave(fence->lock, flags); | |
212 | ||
213 | if (!fence->ops->enable_signaling(fence)) | |
214 | fence_signal_locked(fence); | |
215 | ||
216 | spin_unlock_irqrestore(fence->lock, flags); | |
217 | } | |
218 | } | |
219 | EXPORT_SYMBOL(fence_enable_sw_signaling); | |
220 | ||
221 | /** | |
222 | * fence_add_callback - add a callback to be called when the fence | |
223 | * is signaled | |
224 | * @fence: [in] the fence to wait on | |
225 | * @cb: [in] the callback to register | |
226 | * @func: [in] the function to call | |
227 | * | |
228 | * cb will be initialized by fence_add_callback, no initialization | |
229 | * by the caller is required. Any number of callbacks can be registered | |
230 | * to a fence, but a callback can only be registered to one fence at a time. | |
231 | * | |
232 | * Note that the callback can be called from an atomic context. If | |
233 | * fence is already signaled, this function will return -ENOENT (and | |
234 | * *not* call the callback) | |
235 | * | |
236 | * Add a software callback to the fence. Same restrictions apply to | |
237 | * refcount as it does to fence_wait, however the caller doesn't need to | |
238 | * keep a refcount to fence afterwards: when software access is enabled, | |
239 | * the creator of the fence is required to keep the fence alive until | |
240 | * after it signals with fence_signal. The callback itself can be called | |
241 | * from irq context. | |
242 | * | |
243 | */ | |
244 | int fence_add_callback(struct fence *fence, struct fence_cb *cb, | |
245 | fence_func_t func) | |
246 | { | |
247 | unsigned long flags; | |
248 | int ret = 0; | |
249 | bool was_set; | |
250 | ||
251 | if (WARN_ON(!fence || !func)) | |
252 | return -EINVAL; | |
253 | ||
254 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { | |
255 | INIT_LIST_HEAD(&cb->node); | |
256 | return -ENOENT; | |
257 | } | |
258 | ||
259 | spin_lock_irqsave(fence->lock, flags); | |
260 | ||
261 | was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags); | |
262 | ||
263 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
264 | ret = -ENOENT; | |
265 | else if (!was_set) { | |
266 | trace_fence_enable_signal(fence); | |
267 | ||
268 | if (!fence->ops->enable_signaling(fence)) { | |
269 | fence_signal_locked(fence); | |
270 | ret = -ENOENT; | |
271 | } | |
272 | } | |
273 | ||
274 | if (!ret) { | |
275 | cb->func = func; | |
276 | list_add_tail(&cb->node, &fence->cb_list); | |
277 | } else | |
278 | INIT_LIST_HEAD(&cb->node); | |
279 | spin_unlock_irqrestore(fence->lock, flags); | |
280 | ||
281 | return ret; | |
282 | } | |
283 | EXPORT_SYMBOL(fence_add_callback); | |
284 | ||
285 | /** | |
286 | * fence_remove_callback - remove a callback from the signaling list | |
287 | * @fence: [in] the fence to wait on | |
288 | * @cb: [in] the callback to remove | |
289 | * | |
290 | * Remove a previously queued callback from the fence. This function returns | |
f353d71f | 291 | * true if the callback is successfully removed, or false if the fence has |
e941759c ML |
292 | * already been signaled. |
293 | * | |
294 | * *WARNING*: | |
295 | * Cancelling a callback should only be done if you really know what you're | |
296 | * doing, since deadlocks and race conditions could occur all too easily. For | |
297 | * this reason, it should only ever be done on hardware lockup recovery, | |
298 | * with a reference held to the fence. | |
299 | */ | |
300 | bool | |
301 | fence_remove_callback(struct fence *fence, struct fence_cb *cb) | |
302 | { | |
303 | unsigned long flags; | |
304 | bool ret; | |
305 | ||
306 | spin_lock_irqsave(fence->lock, flags); | |
307 | ||
308 | ret = !list_empty(&cb->node); | |
309 | if (ret) | |
310 | list_del_init(&cb->node); | |
311 | ||
312 | spin_unlock_irqrestore(fence->lock, flags); | |
313 | ||
314 | return ret; | |
315 | } | |
316 | EXPORT_SYMBOL(fence_remove_callback); | |
317 | ||
318 | struct default_wait_cb { | |
319 | struct fence_cb base; | |
320 | struct task_struct *task; | |
321 | }; | |
322 | ||
323 | static void | |
324 | fence_default_wait_cb(struct fence *fence, struct fence_cb *cb) | |
325 | { | |
326 | struct default_wait_cb *wait = | |
327 | container_of(cb, struct default_wait_cb, base); | |
328 | ||
329 | wake_up_state(wait->task, TASK_NORMAL); | |
330 | } | |
331 | ||
332 | /** | |
333 | * fence_default_wait - default sleep until the fence gets signaled | |
334 | * or until timeout elapses | |
335 | * @fence: [in] the fence to wait on | |
336 | * @intr: [in] if true, do an interruptible wait | |
337 | * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT | |
338 | * | |
339 | * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the | |
340 | * remaining timeout in jiffies on success. | |
341 | */ | |
342 | signed long | |
343 | fence_default_wait(struct fence *fence, bool intr, signed long timeout) | |
344 | { | |
345 | struct default_wait_cb cb; | |
346 | unsigned long flags; | |
347 | signed long ret = timeout; | |
348 | bool was_set; | |
349 | ||
350 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
351 | return timeout; | |
352 | ||
353 | spin_lock_irqsave(fence->lock, flags); | |
354 | ||
355 | if (intr && signal_pending(current)) { | |
356 | ret = -ERESTARTSYS; | |
357 | goto out; | |
358 | } | |
359 | ||
360 | was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags); | |
361 | ||
362 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
363 | goto out; | |
364 | ||
365 | if (!was_set) { | |
366 | trace_fence_enable_signal(fence); | |
367 | ||
368 | if (!fence->ops->enable_signaling(fence)) { | |
369 | fence_signal_locked(fence); | |
370 | goto out; | |
371 | } | |
372 | } | |
373 | ||
374 | cb.base.func = fence_default_wait_cb; | |
375 | cb.task = current; | |
376 | list_add(&cb.base.node, &fence->cb_list); | |
377 | ||
378 | while (!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) { | |
379 | if (intr) | |
380 | __set_current_state(TASK_INTERRUPTIBLE); | |
381 | else | |
382 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
383 | spin_unlock_irqrestore(fence->lock, flags); | |
384 | ||
385 | ret = schedule_timeout(ret); | |
386 | ||
387 | spin_lock_irqsave(fence->lock, flags); | |
388 | if (ret > 0 && intr && signal_pending(current)) | |
389 | ret = -ERESTARTSYS; | |
390 | } | |
391 | ||
392 | if (!list_empty(&cb.base.node)) | |
393 | list_del(&cb.base.node); | |
394 | __set_current_state(TASK_RUNNING); | |
395 | ||
396 | out: | |
397 | spin_unlock_irqrestore(fence->lock, flags); | |
398 | return ret; | |
399 | } | |
400 | EXPORT_SYMBOL(fence_default_wait); | |
401 | ||
a519435a CK |
402 | static bool |
403 | fence_test_signaled_any(struct fence **fences, uint32_t count) | |
404 | { | |
405 | int i; | |
406 | ||
407 | for (i = 0; i < count; ++i) { | |
408 | struct fence *fence = fences[i]; | |
409 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
410 | return true; | |
411 | } | |
412 | return false; | |
413 | } | |
414 | ||
415 | /** | |
416 | * fence_wait_any_timeout - sleep until any fence gets signaled | |
417 | * or until timeout elapses | |
418 | * @fences: [in] array of fences to wait on | |
419 | * @count: [in] number of fences to wait on | |
420 | * @intr: [in] if true, do an interruptible wait | |
421 | * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT | |
422 | * | |
423 | * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if | |
424 | * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies | |
425 | * on success. | |
426 | * | |
427 | * Synchronous waits for the first fence in the array to be signaled. The | |
428 | * caller needs to hold a reference to all fences in the array, otherwise a | |
429 | * fence might be freed before return, resulting in undefined behavior. | |
430 | */ | |
431 | signed long | |
432 | fence_wait_any_timeout(struct fence **fences, uint32_t count, | |
433 | bool intr, signed long timeout) | |
434 | { | |
435 | struct default_wait_cb *cb; | |
436 | signed long ret = timeout; | |
437 | unsigned i; | |
438 | ||
439 | if (WARN_ON(!fences || !count || timeout < 0)) | |
440 | return -EINVAL; | |
441 | ||
442 | if (timeout == 0) { | |
443 | for (i = 0; i < count; ++i) | |
444 | if (fence_is_signaled(fences[i])) | |
445 | return 1; | |
446 | ||
447 | return 0; | |
448 | } | |
449 | ||
450 | cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL); | |
451 | if (cb == NULL) { | |
452 | ret = -ENOMEM; | |
453 | goto err_free_cb; | |
454 | } | |
455 | ||
456 | for (i = 0; i < count; ++i) { | |
457 | struct fence *fence = fences[i]; | |
458 | ||
459 | if (fence->ops->wait != fence_default_wait) { | |
460 | ret = -EINVAL; | |
461 | goto fence_rm_cb; | |
462 | } | |
463 | ||
464 | cb[i].task = current; | |
465 | if (fence_add_callback(fence, &cb[i].base, | |
466 | fence_default_wait_cb)) { | |
467 | /* This fence is already signaled */ | |
468 | goto fence_rm_cb; | |
469 | } | |
470 | } | |
471 | ||
472 | while (ret > 0) { | |
473 | if (intr) | |
474 | set_current_state(TASK_INTERRUPTIBLE); | |
475 | else | |
476 | set_current_state(TASK_UNINTERRUPTIBLE); | |
477 | ||
478 | if (fence_test_signaled_any(fences, count)) | |
479 | break; | |
480 | ||
481 | ret = schedule_timeout(ret); | |
482 | ||
483 | if (ret > 0 && intr && signal_pending(current)) | |
484 | ret = -ERESTARTSYS; | |
485 | } | |
486 | ||
487 | __set_current_state(TASK_RUNNING); | |
488 | ||
489 | fence_rm_cb: | |
490 | while (i-- > 0) | |
491 | fence_remove_callback(fences[i], &cb[i].base); | |
492 | ||
493 | err_free_cb: | |
494 | kfree(cb); | |
495 | ||
496 | return ret; | |
497 | } | |
498 | EXPORT_SYMBOL(fence_wait_any_timeout); | |
499 | ||
e941759c ML |
500 | /** |
501 | * fence_init - Initialize a custom fence. | |
502 | * @fence: [in] the fence to initialize | |
503 | * @ops: [in] the fence_ops for operations on this fence | |
504 | * @lock: [in] the irqsafe spinlock to use for locking this fence | |
505 | * @context: [in] the execution context this fence is run on | |
506 | * @seqno: [in] a linear increasing sequence number for this context | |
507 | * | |
508 | * Initializes an allocated fence, the caller doesn't have to keep its | |
509 | * refcount after committing with this fence, but it will need to hold a | |
510 | * refcount again if fence_ops.enable_signaling gets called. This can | |
511 | * be used for other implementing other types of fence. | |
512 | * | |
513 | * context and seqno are used for easy comparison between fences, allowing | |
514 | * to check which fence is later by simply using fence_later. | |
515 | */ | |
516 | void | |
517 | fence_init(struct fence *fence, const struct fence_ops *ops, | |
76bf0db5 | 518 | spinlock_t *lock, u64 context, unsigned seqno) |
e941759c ML |
519 | { |
520 | BUG_ON(!lock); | |
521 | BUG_ON(!ops || !ops->wait || !ops->enable_signaling || | |
522 | !ops->get_driver_name || !ops->get_timeline_name); | |
523 | ||
524 | kref_init(&fence->refcount); | |
525 | fence->ops = ops; | |
526 | INIT_LIST_HEAD(&fence->cb_list); | |
527 | fence->lock = lock; | |
528 | fence->context = context; | |
529 | fence->seqno = seqno; | |
530 | fence->flags = 0UL; | |
531 | ||
532 | trace_fence_init(fence); | |
533 | } | |
534 | EXPORT_SYMBOL(fence_init); |