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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 | ||
32 | /** | |
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 | */ | |
38 | static atomic_t fence_context_counter = ATOMIC_INIT(0); | |
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 | */ | |
47 | unsigned fence_context_alloc(unsigned num) | |
48 | { | |
49 | BUG_ON(!num); | |
50 | return atomic_add_return(num, &fence_context_counter) - num; | |
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 | ||
71 | if (WARN_ON(!fence)) | |
72 | return -EINVAL; | |
73 | ||
74 | if (!ktime_to_ns(fence->timestamp)) { | |
75 | fence->timestamp = ktime_get(); | |
76 | smp_mb__before_atomic(); | |
77 | } | |
78 | ||
79 | if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { | |
80 | ret = -EINVAL; | |
81 | ||
82 | /* | |
83 | * we might have raced with the unlocked fence_signal, | |
84 | * still run through all callbacks | |
85 | */ | |
86 | } else | |
87 | trace_fence_signaled(fence); | |
88 | ||
89 | list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { | |
90 | list_del_init(&cur->node); | |
91 | cur->func(fence, cur); | |
92 | } | |
93 | return ret; | |
94 | } | |
95 | EXPORT_SYMBOL(fence_signal_locked); | |
96 | ||
97 | /** | |
98 | * fence_signal - signal completion of a fence | |
99 | * @fence: the fence to signal | |
100 | * | |
101 | * Signal completion for software callbacks on a fence, this will unblock | |
102 | * fence_wait() calls and run all the callbacks added with | |
103 | * fence_add_callback(). Can be called multiple times, but since a fence | |
104 | * can only go from unsignaled to signaled state, it will only be effective | |
105 | * the first time. | |
106 | */ | |
107 | int fence_signal(struct fence *fence) | |
108 | { | |
109 | unsigned long flags; | |
110 | ||
111 | if (!fence) | |
112 | return -EINVAL; | |
113 | ||
114 | if (!ktime_to_ns(fence->timestamp)) { | |
115 | fence->timestamp = ktime_get(); | |
116 | smp_mb__before_atomic(); | |
117 | } | |
118 | ||
119 | if (test_and_set_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
120 | return -EINVAL; | |
121 | ||
122 | trace_fence_signaled(fence); | |
123 | ||
124 | if (test_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) { | |
125 | struct fence_cb *cur, *tmp; | |
126 | ||
127 | spin_lock_irqsave(fence->lock, flags); | |
128 | list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) { | |
129 | list_del_init(&cur->node); | |
130 | cur->func(fence, cur); | |
131 | } | |
132 | spin_unlock_irqrestore(fence->lock, flags); | |
133 | } | |
134 | return 0; | |
135 | } | |
136 | EXPORT_SYMBOL(fence_signal); | |
137 | ||
138 | /** | |
139 | * fence_wait_timeout - sleep until the fence gets signaled | |
140 | * or until timeout elapses | |
141 | * @fence: [in] the fence to wait on | |
142 | * @intr: [in] if true, do an interruptible wait | |
143 | * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT | |
144 | * | |
145 | * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the | |
146 | * remaining timeout in jiffies on success. Other error values may be | |
147 | * returned on custom implementations. | |
148 | * | |
149 | * Performs a synchronous wait on this fence. It is assumed the caller | |
150 | * directly or indirectly (buf-mgr between reservation and committing) | |
151 | * holds a reference to the fence, otherwise the fence might be | |
152 | * freed before return, resulting in undefined behavior. | |
153 | */ | |
154 | signed long | |
155 | fence_wait_timeout(struct fence *fence, bool intr, signed long timeout) | |
156 | { | |
157 | signed long ret; | |
158 | ||
159 | if (WARN_ON(timeout < 0)) | |
160 | return -EINVAL; | |
161 | ||
162 | trace_fence_wait_start(fence); | |
163 | ret = fence->ops->wait(fence, intr, timeout); | |
164 | trace_fence_wait_end(fence); | |
165 | return ret; | |
166 | } | |
167 | EXPORT_SYMBOL(fence_wait_timeout); | |
168 | ||
169 | void fence_release(struct kref *kref) | |
170 | { | |
171 | struct fence *fence = | |
172 | container_of(kref, struct fence, refcount); | |
173 | ||
174 | trace_fence_destroy(fence); | |
175 | ||
176 | BUG_ON(!list_empty(&fence->cb_list)); | |
177 | ||
178 | if (fence->ops->release) | |
179 | fence->ops->release(fence); | |
180 | else | |
181 | fence_free(fence); | |
182 | } | |
183 | EXPORT_SYMBOL(fence_release); | |
184 | ||
185 | void fence_free(struct fence *fence) | |
186 | { | |
3c3b177a | 187 | kfree_rcu(fence, rcu); |
e941759c ML |
188 | } |
189 | EXPORT_SYMBOL(fence_free); | |
190 | ||
191 | /** | |
192 | * fence_enable_sw_signaling - enable signaling on fence | |
193 | * @fence: [in] the fence to enable | |
194 | * | |
195 | * this will request for sw signaling to be enabled, to make the fence | |
196 | * complete as soon as possible | |
197 | */ | |
198 | void fence_enable_sw_signaling(struct fence *fence) | |
199 | { | |
200 | unsigned long flags; | |
201 | ||
202 | if (!test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags) && | |
203 | !test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { | |
204 | trace_fence_enable_signal(fence); | |
205 | ||
206 | spin_lock_irqsave(fence->lock, flags); | |
207 | ||
208 | if (!fence->ops->enable_signaling(fence)) | |
209 | fence_signal_locked(fence); | |
210 | ||
211 | spin_unlock_irqrestore(fence->lock, flags); | |
212 | } | |
213 | } | |
214 | EXPORT_SYMBOL(fence_enable_sw_signaling); | |
215 | ||
216 | /** | |
217 | * fence_add_callback - add a callback to be called when the fence | |
218 | * is signaled | |
219 | * @fence: [in] the fence to wait on | |
220 | * @cb: [in] the callback to register | |
221 | * @func: [in] the function to call | |
222 | * | |
223 | * cb will be initialized by fence_add_callback, no initialization | |
224 | * by the caller is required. Any number of callbacks can be registered | |
225 | * to a fence, but a callback can only be registered to one fence at a time. | |
226 | * | |
227 | * Note that the callback can be called from an atomic context. If | |
228 | * fence is already signaled, this function will return -ENOENT (and | |
229 | * *not* call the callback) | |
230 | * | |
231 | * Add a software callback to the fence. Same restrictions apply to | |
232 | * refcount as it does to fence_wait, however the caller doesn't need to | |
233 | * keep a refcount to fence afterwards: when software access is enabled, | |
234 | * the creator of the fence is required to keep the fence alive until | |
235 | * after it signals with fence_signal. The callback itself can be called | |
236 | * from irq context. | |
237 | * | |
238 | */ | |
239 | int fence_add_callback(struct fence *fence, struct fence_cb *cb, | |
240 | fence_func_t func) | |
241 | { | |
242 | unsigned long flags; | |
243 | int ret = 0; | |
244 | bool was_set; | |
245 | ||
246 | if (WARN_ON(!fence || !func)) | |
247 | return -EINVAL; | |
248 | ||
249 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { | |
250 | INIT_LIST_HEAD(&cb->node); | |
251 | return -ENOENT; | |
252 | } | |
253 | ||
254 | spin_lock_irqsave(fence->lock, flags); | |
255 | ||
256 | was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags); | |
257 | ||
258 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
259 | ret = -ENOENT; | |
260 | else if (!was_set) { | |
261 | trace_fence_enable_signal(fence); | |
262 | ||
263 | if (!fence->ops->enable_signaling(fence)) { | |
264 | fence_signal_locked(fence); | |
265 | ret = -ENOENT; | |
266 | } | |
267 | } | |
268 | ||
269 | if (!ret) { | |
270 | cb->func = func; | |
271 | list_add_tail(&cb->node, &fence->cb_list); | |
272 | } else | |
273 | INIT_LIST_HEAD(&cb->node); | |
274 | spin_unlock_irqrestore(fence->lock, flags); | |
275 | ||
276 | return ret; | |
277 | } | |
278 | EXPORT_SYMBOL(fence_add_callback); | |
279 | ||
280 | /** | |
281 | * fence_remove_callback - remove a callback from the signaling list | |
282 | * @fence: [in] the fence to wait on | |
283 | * @cb: [in] the callback to remove | |
284 | * | |
285 | * Remove a previously queued callback from the fence. This function returns | |
286 | * true if the callback is succesfully removed, or false if the fence has | |
287 | * already been signaled. | |
288 | * | |
289 | * *WARNING*: | |
290 | * Cancelling a callback should only be done if you really know what you're | |
291 | * doing, since deadlocks and race conditions could occur all too easily. For | |
292 | * this reason, it should only ever be done on hardware lockup recovery, | |
293 | * with a reference held to the fence. | |
294 | */ | |
295 | bool | |
296 | fence_remove_callback(struct fence *fence, struct fence_cb *cb) | |
297 | { | |
298 | unsigned long flags; | |
299 | bool ret; | |
300 | ||
301 | spin_lock_irqsave(fence->lock, flags); | |
302 | ||
303 | ret = !list_empty(&cb->node); | |
304 | if (ret) | |
305 | list_del_init(&cb->node); | |
306 | ||
307 | spin_unlock_irqrestore(fence->lock, flags); | |
308 | ||
309 | return ret; | |
310 | } | |
311 | EXPORT_SYMBOL(fence_remove_callback); | |
312 | ||
313 | struct default_wait_cb { | |
314 | struct fence_cb base; | |
315 | struct task_struct *task; | |
316 | }; | |
317 | ||
318 | static void | |
319 | fence_default_wait_cb(struct fence *fence, struct fence_cb *cb) | |
320 | { | |
321 | struct default_wait_cb *wait = | |
322 | container_of(cb, struct default_wait_cb, base); | |
323 | ||
324 | wake_up_state(wait->task, TASK_NORMAL); | |
325 | } | |
326 | ||
327 | /** | |
328 | * fence_default_wait - default sleep until the fence gets signaled | |
329 | * or until timeout elapses | |
330 | * @fence: [in] the fence to wait on | |
331 | * @intr: [in] if true, do an interruptible wait | |
332 | * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT | |
333 | * | |
334 | * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the | |
335 | * remaining timeout in jiffies on success. | |
336 | */ | |
337 | signed long | |
338 | fence_default_wait(struct fence *fence, bool intr, signed long timeout) | |
339 | { | |
340 | struct default_wait_cb cb; | |
341 | unsigned long flags; | |
342 | signed long ret = timeout; | |
343 | bool was_set; | |
344 | ||
345 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
346 | return timeout; | |
347 | ||
348 | spin_lock_irqsave(fence->lock, flags); | |
349 | ||
350 | if (intr && signal_pending(current)) { | |
351 | ret = -ERESTARTSYS; | |
352 | goto out; | |
353 | } | |
354 | ||
355 | was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags); | |
356 | ||
357 | if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) | |
358 | goto out; | |
359 | ||
360 | if (!was_set) { | |
361 | trace_fence_enable_signal(fence); | |
362 | ||
363 | if (!fence->ops->enable_signaling(fence)) { | |
364 | fence_signal_locked(fence); | |
365 | goto out; | |
366 | } | |
367 | } | |
368 | ||
369 | cb.base.func = fence_default_wait_cb; | |
370 | cb.task = current; | |
371 | list_add(&cb.base.node, &fence->cb_list); | |
372 | ||
373 | while (!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) { | |
374 | if (intr) | |
375 | __set_current_state(TASK_INTERRUPTIBLE); | |
376 | else | |
377 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
378 | spin_unlock_irqrestore(fence->lock, flags); | |
379 | ||
380 | ret = schedule_timeout(ret); | |
381 | ||
382 | spin_lock_irqsave(fence->lock, flags); | |
383 | if (ret > 0 && intr && signal_pending(current)) | |
384 | ret = -ERESTARTSYS; | |
385 | } | |
386 | ||
387 | if (!list_empty(&cb.base.node)) | |
388 | list_del(&cb.base.node); | |
389 | __set_current_state(TASK_RUNNING); | |
390 | ||
391 | out: | |
392 | spin_unlock_irqrestore(fence->lock, flags); | |
393 | return ret; | |
394 | } | |
395 | EXPORT_SYMBOL(fence_default_wait); | |
396 | ||
397 | /** | |
398 | * fence_init - Initialize a custom fence. | |
399 | * @fence: [in] the fence to initialize | |
400 | * @ops: [in] the fence_ops for operations on this fence | |
401 | * @lock: [in] the irqsafe spinlock to use for locking this fence | |
402 | * @context: [in] the execution context this fence is run on | |
403 | * @seqno: [in] a linear increasing sequence number for this context | |
404 | * | |
405 | * Initializes an allocated fence, the caller doesn't have to keep its | |
406 | * refcount after committing with this fence, but it will need to hold a | |
407 | * refcount again if fence_ops.enable_signaling gets called. This can | |
408 | * be used for other implementing other types of fence. | |
409 | * | |
410 | * context and seqno are used for easy comparison between fences, allowing | |
411 | * to check which fence is later by simply using fence_later. | |
412 | */ | |
413 | void | |
414 | fence_init(struct fence *fence, const struct fence_ops *ops, | |
415 | spinlock_t *lock, unsigned context, unsigned seqno) | |
416 | { | |
417 | BUG_ON(!lock); | |
418 | BUG_ON(!ops || !ops->wait || !ops->enable_signaling || | |
419 | !ops->get_driver_name || !ops->get_timeline_name); | |
420 | ||
421 | kref_init(&fence->refcount); | |
422 | fence->ops = ops; | |
423 | INIT_LIST_HEAD(&fence->cb_list); | |
424 | fence->lock = lock; | |
425 | fence->context = context; | |
426 | fence->seqno = seqno; | |
427 | fence->flags = 0UL; | |
428 | ||
429 | trace_fence_init(fence); | |
430 | } | |
431 | EXPORT_SYMBOL(fence_init); |