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Maarten Lankhorste9417592014-07-01 12:57:14 +02001/*
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
29EXPORT_TRACEPOINT_SYMBOL(fence_annotate_wait_on);
30EXPORT_TRACEPOINT_SYMBOL(fence_emit);
31
Thierry Redinge9f3b792014-08-08 12:42:32 +020032/*
Maarten Lankhorste9417592014-07-01 12:57:14 +020033 * 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 */
38static 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 */
47unsigned fence_context_alloc(unsigned num)
48{
49 BUG_ON(!num);
50 return atomic_add_return(num, &fence_context_counter) - num;
51}
52EXPORT_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 */
66int 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}
95EXPORT_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 */
107int 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}
136EXPORT_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 */
154signed long
155fence_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
Jammy Zhou847b19a32015-01-21 18:35:48 +0800162 if (timeout == 0)
163 return fence_is_signaled(fence);
164
Maarten Lankhorste9417592014-07-01 12:57:14 +0200165 trace_fence_wait_start(fence);
166 ret = fence->ops->wait(fence, intr, timeout);
167 trace_fence_wait_end(fence);
168 return ret;
169}
170EXPORT_SYMBOL(fence_wait_timeout);
171
172void fence_release(struct kref *kref)
173{
174 struct fence *fence =
175 container_of(kref, struct fence, refcount);
176
177 trace_fence_destroy(fence);
178
179 BUG_ON(!list_empty(&fence->cb_list));
180
181 if (fence->ops->release)
182 fence->ops->release(fence);
183 else
184 fence_free(fence);
185}
186EXPORT_SYMBOL(fence_release);
187
188void fence_free(struct fence *fence)
189{
Maarten Lankhorst3c3b1772014-07-01 12:58:00 +0200190 kfree_rcu(fence, rcu);
Maarten Lankhorste9417592014-07-01 12:57:14 +0200191}
192EXPORT_SYMBOL(fence_free);
193
194/**
195 * fence_enable_sw_signaling - enable signaling on fence
196 * @fence: [in] the fence to enable
197 *
198 * this will request for sw signaling to be enabled, to make the fence
199 * complete as soon as possible
200 */
201void fence_enable_sw_signaling(struct fence *fence)
202{
203 unsigned long flags;
204
205 if (!test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags) &&
206 !test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
207 trace_fence_enable_signal(fence);
208
209 spin_lock_irqsave(fence->lock, flags);
210
211 if (!fence->ops->enable_signaling(fence))
212 fence_signal_locked(fence);
213
214 spin_unlock_irqrestore(fence->lock, flags);
215 }
216}
217EXPORT_SYMBOL(fence_enable_sw_signaling);
218
219/**
220 * fence_add_callback - add a callback to be called when the fence
221 * is signaled
222 * @fence: [in] the fence to wait on
223 * @cb: [in] the callback to register
224 * @func: [in] the function to call
225 *
226 * cb will be initialized by fence_add_callback, no initialization
227 * by the caller is required. Any number of callbacks can be registered
228 * to a fence, but a callback can only be registered to one fence at a time.
229 *
230 * Note that the callback can be called from an atomic context. If
231 * fence is already signaled, this function will return -ENOENT (and
232 * *not* call the callback)
233 *
234 * Add a software callback to the fence. Same restrictions apply to
235 * refcount as it does to fence_wait, however the caller doesn't need to
236 * keep a refcount to fence afterwards: when software access is enabled,
237 * the creator of the fence is required to keep the fence alive until
238 * after it signals with fence_signal. The callback itself can be called
239 * from irq context.
240 *
241 */
242int fence_add_callback(struct fence *fence, struct fence_cb *cb,
243 fence_func_t func)
244{
245 unsigned long flags;
246 int ret = 0;
247 bool was_set;
248
249 if (WARN_ON(!fence || !func))
250 return -EINVAL;
251
252 if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
253 INIT_LIST_HEAD(&cb->node);
254 return -ENOENT;
255 }
256
257 spin_lock_irqsave(fence->lock, flags);
258
259 was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags);
260
261 if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
262 ret = -ENOENT;
263 else if (!was_set) {
264 trace_fence_enable_signal(fence);
265
266 if (!fence->ops->enable_signaling(fence)) {
267 fence_signal_locked(fence);
268 ret = -ENOENT;
269 }
270 }
271
272 if (!ret) {
273 cb->func = func;
274 list_add_tail(&cb->node, &fence->cb_list);
275 } else
276 INIT_LIST_HEAD(&cb->node);
277 spin_unlock_irqrestore(fence->lock, flags);
278
279 return ret;
280}
281EXPORT_SYMBOL(fence_add_callback);
282
283/**
284 * fence_remove_callback - remove a callback from the signaling list
285 * @fence: [in] the fence to wait on
286 * @cb: [in] the callback to remove
287 *
288 * Remove a previously queued callback from the fence. This function returns
Masanari Iidaf353d712014-10-22 00:00:14 +0900289 * true if the callback is successfully removed, or false if the fence has
Maarten Lankhorste9417592014-07-01 12:57:14 +0200290 * already been signaled.
291 *
292 * *WARNING*:
293 * Cancelling a callback should only be done if you really know what you're
294 * doing, since deadlocks and race conditions could occur all too easily. For
295 * this reason, it should only ever be done on hardware lockup recovery,
296 * with a reference held to the fence.
297 */
298bool
299fence_remove_callback(struct fence *fence, struct fence_cb *cb)
300{
301 unsigned long flags;
302 bool ret;
303
304 spin_lock_irqsave(fence->lock, flags);
305
306 ret = !list_empty(&cb->node);
307 if (ret)
308 list_del_init(&cb->node);
309
310 spin_unlock_irqrestore(fence->lock, flags);
311
312 return ret;
313}
314EXPORT_SYMBOL(fence_remove_callback);
315
316struct default_wait_cb {
317 struct fence_cb base;
318 struct task_struct *task;
319};
320
321static void
322fence_default_wait_cb(struct fence *fence, struct fence_cb *cb)
323{
324 struct default_wait_cb *wait =
325 container_of(cb, struct default_wait_cb, base);
326
327 wake_up_state(wait->task, TASK_NORMAL);
328}
329
330/**
331 * fence_default_wait - default sleep until the fence gets signaled
332 * or until timeout elapses
333 * @fence: [in] the fence to wait on
334 * @intr: [in] if true, do an interruptible wait
335 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
336 *
337 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
338 * remaining timeout in jiffies on success.
339 */
340signed long
341fence_default_wait(struct fence *fence, bool intr, signed long timeout)
342{
343 struct default_wait_cb cb;
344 unsigned long flags;
345 signed long ret = timeout;
346 bool was_set;
347
348 if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
349 return timeout;
350
351 spin_lock_irqsave(fence->lock, flags);
352
353 if (intr && signal_pending(current)) {
354 ret = -ERESTARTSYS;
355 goto out;
356 }
357
358 was_set = test_and_set_bit(FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags);
359
360 if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags))
361 goto out;
362
363 if (!was_set) {
364 trace_fence_enable_signal(fence);
365
366 if (!fence->ops->enable_signaling(fence)) {
367 fence_signal_locked(fence);
368 goto out;
369 }
370 }
371
372 cb.base.func = fence_default_wait_cb;
373 cb.task = current;
374 list_add(&cb.base.node, &fence->cb_list);
375
376 while (!test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
377 if (intr)
378 __set_current_state(TASK_INTERRUPTIBLE);
379 else
380 __set_current_state(TASK_UNINTERRUPTIBLE);
381 spin_unlock_irqrestore(fence->lock, flags);
382
383 ret = schedule_timeout(ret);
384
385 spin_lock_irqsave(fence->lock, flags);
386 if (ret > 0 && intr && signal_pending(current))
387 ret = -ERESTARTSYS;
388 }
389
390 if (!list_empty(&cb.base.node))
391 list_del(&cb.base.node);
392 __set_current_state(TASK_RUNNING);
393
394out:
395 spin_unlock_irqrestore(fence->lock, flags);
396 return ret;
397}
398EXPORT_SYMBOL(fence_default_wait);
399
400/**
401 * fence_init - Initialize a custom fence.
402 * @fence: [in] the fence to initialize
403 * @ops: [in] the fence_ops for operations on this fence
404 * @lock: [in] the irqsafe spinlock to use for locking this fence
405 * @context: [in] the execution context this fence is run on
406 * @seqno: [in] a linear increasing sequence number for this context
407 *
408 * Initializes an allocated fence, the caller doesn't have to keep its
409 * refcount after committing with this fence, but it will need to hold a
410 * refcount again if fence_ops.enable_signaling gets called. This can
411 * be used for other implementing other types of fence.
412 *
413 * context and seqno are used for easy comparison between fences, allowing
414 * to check which fence is later by simply using fence_later.
415 */
416void
417fence_init(struct fence *fence, const struct fence_ops *ops,
418 spinlock_t *lock, unsigned context, unsigned seqno)
419{
420 BUG_ON(!lock);
421 BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
422 !ops->get_driver_name || !ops->get_timeline_name);
423
424 kref_init(&fence->refcount);
425 fence->ops = ops;
426 INIT_LIST_HEAD(&fence->cb_list);
427 fence->lock = lock;
428 fence->context = context;
429 fence->seqno = seqno;
430 fence->flags = 0UL;
431
432 trace_fence_init(fence);
433}
434EXPORT_SYMBOL(fence_init);