3aa8733f832af9596f664b0f525de3620babf8fc
[sfrench/cifs-2.6.git] / drivers / dma-buf / dma-fence.c
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/dma-fence.h>
25 #include <linux/sched/signal.h>
26
27 #define CREATE_TRACE_POINTS
28 #include <trace/events/dma_fence.h>
29
30 EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit);
31 EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal);
32
33 static DEFINE_SPINLOCK(dma_fence_stub_lock);
34 static struct dma_fence dma_fence_stub;
35
36 /*
37  * fence context counter: each execution context should have its own
38  * fence context, this allows checking if fences belong to the same
39  * context or not. One device can have multiple separate contexts,
40  * and they're used if some engine can run independently of another.
41  */
42 static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(1);
43
44 /**
45  * DOC: DMA fences overview
46  *
47  * DMA fences, represented by &struct dma_fence, are the kernel internal
48  * synchronization primitive for DMA operations like GPU rendering, video
49  * encoding/decoding, or displaying buffers on a screen.
50  *
51  * A fence is initialized using dma_fence_init() and completed using
52  * dma_fence_signal(). Fences are associated with a context, allocated through
53  * dma_fence_context_alloc(), and all fences on the same context are
54  * fully ordered.
55  *
56  * Since the purposes of fences is to facilitate cross-device and
57  * cross-application synchronization, there's multiple ways to use one:
58  *
59  * - Individual fences can be exposed as a &sync_file, accessed as a file
60  *   descriptor from userspace, created by calling sync_file_create(). This is
61  *   called explicit fencing, since userspace passes around explicit
62  *   synchronization points.
63  *
64  * - Some subsystems also have their own explicit fencing primitives, like
65  *   &drm_syncobj. Compared to &sync_file, a &drm_syncobj allows the underlying
66  *   fence to be updated.
67  *
68  * - Then there's also implicit fencing, where the synchronization points are
69  *   implicitly passed around as part of shared &dma_buf instances. Such
70  *   implicit fences are stored in &struct reservation_object through the
71  *   &dma_buf.resv pointer.
72  */
73
74 static const char *dma_fence_stub_get_name(struct dma_fence *fence)
75 {
76         return "stub";
77 }
78
79 static const struct dma_fence_ops dma_fence_stub_ops = {
80         .get_driver_name = dma_fence_stub_get_name,
81         .get_timeline_name = dma_fence_stub_get_name,
82 };
83
84 /**
85  * dma_fence_get_stub - return a signaled fence
86  *
87  * Return a stub fence which is already signaled.
88  */
89 struct dma_fence *dma_fence_get_stub(void)
90 {
91         spin_lock(&dma_fence_stub_lock);
92         if (!dma_fence_stub.ops) {
93                 dma_fence_init(&dma_fence_stub,
94                                &dma_fence_stub_ops,
95                                &dma_fence_stub_lock,
96                                0, 0);
97                 dma_fence_signal_locked(&dma_fence_stub);
98         }
99         spin_unlock(&dma_fence_stub_lock);
100
101         return dma_fence_get(&dma_fence_stub);
102 }
103 EXPORT_SYMBOL(dma_fence_get_stub);
104
105 /**
106  * dma_fence_context_alloc - allocate an array of fence contexts
107  * @num: amount of contexts to allocate
108  *
109  * This function will return the first index of the number of fence contexts
110  * allocated.  The fence context is used for setting &dma_fence.context to a
111  * unique number by passing the context to dma_fence_init().
112  */
113 u64 dma_fence_context_alloc(unsigned num)
114 {
115         WARN_ON(!num);
116         return atomic64_add_return(num, &dma_fence_context_counter) - num;
117 }
118 EXPORT_SYMBOL(dma_fence_context_alloc);
119
120 /**
121  * dma_fence_signal_locked - signal completion of a fence
122  * @fence: the fence to signal
123  *
124  * Signal completion for software callbacks on a fence, this will unblock
125  * dma_fence_wait() calls and run all the callbacks added with
126  * dma_fence_add_callback(). Can be called multiple times, but since a fence
127  * can only go from the unsignaled to the signaled state and not back, it will
128  * only be effective the first time.
129  *
130  * Unlike dma_fence_signal(), this function must be called with &dma_fence.lock
131  * held.
132  *
133  * Returns 0 on success and a negative error value when @fence has been
134  * signalled already.
135  */
136 int dma_fence_signal_locked(struct dma_fence *fence)
137 {
138         struct dma_fence_cb *cur, *tmp;
139         int ret = 0;
140
141         lockdep_assert_held(fence->lock);
142
143         if (WARN_ON(!fence))
144                 return -EINVAL;
145
146         if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
147                 ret = -EINVAL;
148
149                 /*
150                  * we might have raced with the unlocked dma_fence_signal,
151                  * still run through all callbacks
152                  */
153         } else {
154                 fence->timestamp = ktime_get();
155                 set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
156                 trace_dma_fence_signaled(fence);
157         }
158
159         list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
160                 list_del_init(&cur->node);
161                 cur->func(fence, cur);
162         }
163         return ret;
164 }
165 EXPORT_SYMBOL(dma_fence_signal_locked);
166
167 /**
168  * dma_fence_signal - signal completion of a fence
169  * @fence: the fence to signal
170  *
171  * Signal completion for software callbacks on a fence, this will unblock
172  * dma_fence_wait() calls and run all the callbacks added with
173  * dma_fence_add_callback(). Can be called multiple times, but since a fence
174  * can only go from the unsignaled to the signaled state and not back, it will
175  * only be effective the first time.
176  *
177  * Returns 0 on success and a negative error value when @fence has been
178  * signalled already.
179  */
180 int dma_fence_signal(struct dma_fence *fence)
181 {
182         unsigned long flags;
183
184         if (!fence)
185                 return -EINVAL;
186
187         if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
188                 return -EINVAL;
189
190         fence->timestamp = ktime_get();
191         set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
192         trace_dma_fence_signaled(fence);
193
194         if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
195                 struct dma_fence_cb *cur, *tmp;
196
197                 spin_lock_irqsave(fence->lock, flags);
198                 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
199                         list_del_init(&cur->node);
200                         cur->func(fence, cur);
201                 }
202                 spin_unlock_irqrestore(fence->lock, flags);
203         }
204         return 0;
205 }
206 EXPORT_SYMBOL(dma_fence_signal);
207
208 /**
209  * dma_fence_wait_timeout - sleep until the fence gets signaled
210  * or until timeout elapses
211  * @fence: the fence to wait on
212  * @intr: if true, do an interruptible wait
213  * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
214  *
215  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
216  * remaining timeout in jiffies on success. Other error values may be
217  * returned on custom implementations.
218  *
219  * Performs a synchronous wait on this fence. It is assumed the caller
220  * directly or indirectly (buf-mgr between reservation and committing)
221  * holds a reference to the fence, otherwise the fence might be
222  * freed before return, resulting in undefined behavior.
223  *
224  * See also dma_fence_wait() and dma_fence_wait_any_timeout().
225  */
226 signed long
227 dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
228 {
229         signed long ret;
230
231         if (WARN_ON(timeout < 0))
232                 return -EINVAL;
233
234         trace_dma_fence_wait_start(fence);
235         if (fence->ops->wait)
236                 ret = fence->ops->wait(fence, intr, timeout);
237         else
238                 ret = dma_fence_default_wait(fence, intr, timeout);
239         trace_dma_fence_wait_end(fence);
240         return ret;
241 }
242 EXPORT_SYMBOL(dma_fence_wait_timeout);
243
244 /**
245  * dma_fence_release - default relese function for fences
246  * @kref: &dma_fence.recfount
247  *
248  * This is the default release functions for &dma_fence. Drivers shouldn't call
249  * this directly, but instead call dma_fence_put().
250  */
251 void dma_fence_release(struct kref *kref)
252 {
253         struct dma_fence *fence =
254                 container_of(kref, struct dma_fence, refcount);
255
256         trace_dma_fence_destroy(fence);
257
258         /* Failed to signal before release, could be a refcounting issue */
259         WARN_ON(!list_empty(&fence->cb_list));
260
261         if (fence->ops->release)
262                 fence->ops->release(fence);
263         else
264                 dma_fence_free(fence);
265 }
266 EXPORT_SYMBOL(dma_fence_release);
267
268 /**
269  * dma_fence_free - default release function for &dma_fence.
270  * @fence: fence to release
271  *
272  * This is the default implementation for &dma_fence_ops.release. It calls
273  * kfree_rcu() on @fence.
274  */
275 void dma_fence_free(struct dma_fence *fence)
276 {
277         kfree_rcu(fence, rcu);
278 }
279 EXPORT_SYMBOL(dma_fence_free);
280
281 /**
282  * dma_fence_enable_sw_signaling - enable signaling on fence
283  * @fence: the fence to enable
284  *
285  * This will request for sw signaling to be enabled, to make the fence
286  * complete as soon as possible. This calls &dma_fence_ops.enable_signaling
287  * internally.
288  */
289 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
290 {
291         unsigned long flags;
292
293         if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
294                               &fence->flags) &&
295             !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) &&
296             fence->ops->enable_signaling) {
297                 trace_dma_fence_enable_signal(fence);
298
299                 spin_lock_irqsave(fence->lock, flags);
300
301                 if (!fence->ops->enable_signaling(fence))
302                         dma_fence_signal_locked(fence);
303
304                 spin_unlock_irqrestore(fence->lock, flags);
305         }
306 }
307 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
308
309 /**
310  * dma_fence_add_callback - add a callback to be called when the fence
311  * is signaled
312  * @fence: the fence to wait on
313  * @cb: the callback to register
314  * @func: the function to call
315  *
316  * @cb will be initialized by dma_fence_add_callback(), no initialization
317  * by the caller is required. Any number of callbacks can be registered
318  * to a fence, but a callback can only be registered to one fence at a time.
319  *
320  * Note that the callback can be called from an atomic context.  If
321  * fence is already signaled, this function will return -ENOENT (and
322  * *not* call the callback).
323  *
324  * Add a software callback to the fence. Same restrictions apply to
325  * refcount as it does to dma_fence_wait(), however the caller doesn't need to
326  * keep a refcount to fence afterward dma_fence_add_callback() has returned:
327  * when software access is enabled, the creator of the fence is required to keep
328  * the fence alive until after it signals with dma_fence_signal(). The callback
329  * itself can be called from irq context.
330  *
331  * Returns 0 in case of success, -ENOENT if the fence is already signaled
332  * and -EINVAL in case of error.
333  */
334 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
335                            dma_fence_func_t func)
336 {
337         unsigned long flags;
338         int ret = 0;
339         bool was_set;
340
341         if (WARN_ON(!fence || !func))
342                 return -EINVAL;
343
344         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
345                 INIT_LIST_HEAD(&cb->node);
346                 return -ENOENT;
347         }
348
349         spin_lock_irqsave(fence->lock, flags);
350
351         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
352                                    &fence->flags);
353
354         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
355                 ret = -ENOENT;
356         else if (!was_set && fence->ops->enable_signaling) {
357                 trace_dma_fence_enable_signal(fence);
358
359                 if (!fence->ops->enable_signaling(fence)) {
360                         dma_fence_signal_locked(fence);
361                         ret = -ENOENT;
362                 }
363         }
364
365         if (!ret) {
366                 cb->func = func;
367                 list_add_tail(&cb->node, &fence->cb_list);
368         } else
369                 INIT_LIST_HEAD(&cb->node);
370         spin_unlock_irqrestore(fence->lock, flags);
371
372         return ret;
373 }
374 EXPORT_SYMBOL(dma_fence_add_callback);
375
376 /**
377  * dma_fence_get_status - returns the status upon completion
378  * @fence: the dma_fence to query
379  *
380  * This wraps dma_fence_get_status_locked() to return the error status
381  * condition on a signaled fence. See dma_fence_get_status_locked() for more
382  * details.
383  *
384  * Returns 0 if the fence has not yet been signaled, 1 if the fence has
385  * been signaled without an error condition, or a negative error code
386  * if the fence has been completed in err.
387  */
388 int dma_fence_get_status(struct dma_fence *fence)
389 {
390         unsigned long flags;
391         int status;
392
393         spin_lock_irqsave(fence->lock, flags);
394         status = dma_fence_get_status_locked(fence);
395         spin_unlock_irqrestore(fence->lock, flags);
396
397         return status;
398 }
399 EXPORT_SYMBOL(dma_fence_get_status);
400
401 /**
402  * dma_fence_remove_callback - remove a callback from the signaling list
403  * @fence: the fence to wait on
404  * @cb: the callback to remove
405  *
406  * Remove a previously queued callback from the fence. This function returns
407  * true if the callback is successfully removed, or false if the fence has
408  * already been signaled.
409  *
410  * *WARNING*:
411  * Cancelling a callback should only be done if you really know what you're
412  * doing, since deadlocks and race conditions could occur all too easily. For
413  * this reason, it should only ever be done on hardware lockup recovery,
414  * with a reference held to the fence.
415  *
416  * Behaviour is undefined if @cb has not been added to @fence using
417  * dma_fence_add_callback() beforehand.
418  */
419 bool
420 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
421 {
422         unsigned long flags;
423         bool ret;
424
425         spin_lock_irqsave(fence->lock, flags);
426
427         ret = !list_empty(&cb->node);
428         if (ret)
429                 list_del_init(&cb->node);
430
431         spin_unlock_irqrestore(fence->lock, flags);
432
433         return ret;
434 }
435 EXPORT_SYMBOL(dma_fence_remove_callback);
436
437 struct default_wait_cb {
438         struct dma_fence_cb base;
439         struct task_struct *task;
440 };
441
442 static void
443 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
444 {
445         struct default_wait_cb *wait =
446                 container_of(cb, struct default_wait_cb, base);
447
448         wake_up_state(wait->task, TASK_NORMAL);
449 }
450
451 /**
452  * dma_fence_default_wait - default sleep until the fence gets signaled
453  * or until timeout elapses
454  * @fence: the fence to wait on
455  * @intr: if true, do an interruptible wait
456  * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
457  *
458  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
459  * remaining timeout in jiffies on success. If timeout is zero the value one is
460  * returned if the fence is already signaled for consistency with other
461  * functions taking a jiffies timeout.
462  */
463 signed long
464 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
465 {
466         struct default_wait_cb cb;
467         unsigned long flags;
468         signed long ret = timeout ? timeout : 1;
469         bool was_set;
470
471         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
472                 return ret;
473
474         spin_lock_irqsave(fence->lock, flags);
475
476         if (intr && signal_pending(current)) {
477                 ret = -ERESTARTSYS;
478                 goto out;
479         }
480
481         was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
482                                    &fence->flags);
483
484         if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
485                 goto out;
486
487         if (!was_set && fence->ops->enable_signaling) {
488                 trace_dma_fence_enable_signal(fence);
489
490                 if (!fence->ops->enable_signaling(fence)) {
491                         dma_fence_signal_locked(fence);
492                         goto out;
493                 }
494         }
495
496         if (!timeout) {
497                 ret = 0;
498                 goto out;
499         }
500
501         cb.base.func = dma_fence_default_wait_cb;
502         cb.task = current;
503         list_add(&cb.base.node, &fence->cb_list);
504
505         while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
506                 if (intr)
507                         __set_current_state(TASK_INTERRUPTIBLE);
508                 else
509                         __set_current_state(TASK_UNINTERRUPTIBLE);
510                 spin_unlock_irqrestore(fence->lock, flags);
511
512                 ret = schedule_timeout(ret);
513
514                 spin_lock_irqsave(fence->lock, flags);
515                 if (ret > 0 && intr && signal_pending(current))
516                         ret = -ERESTARTSYS;
517         }
518
519         if (!list_empty(&cb.base.node))
520                 list_del(&cb.base.node);
521         __set_current_state(TASK_RUNNING);
522
523 out:
524         spin_unlock_irqrestore(fence->lock, flags);
525         return ret;
526 }
527 EXPORT_SYMBOL(dma_fence_default_wait);
528
529 static bool
530 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
531                             uint32_t *idx)
532 {
533         int i;
534
535         for (i = 0; i < count; ++i) {
536                 struct dma_fence *fence = fences[i];
537                 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
538                         if (idx)
539                                 *idx = i;
540                         return true;
541                 }
542         }
543         return false;
544 }
545
546 /**
547  * dma_fence_wait_any_timeout - sleep until any fence gets signaled
548  * or until timeout elapses
549  * @fences: array of fences to wait on
550  * @count: number of fences to wait on
551  * @intr: if true, do an interruptible wait
552  * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
553  * @idx: used to store the first signaled fence index, meaningful only on
554  *      positive return
555  *
556  * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
557  * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
558  * on success.
559  *
560  * Synchronous waits for the first fence in the array to be signaled. The
561  * caller needs to hold a reference to all fences in the array, otherwise a
562  * fence might be freed before return, resulting in undefined behavior.
563  *
564  * See also dma_fence_wait() and dma_fence_wait_timeout().
565  */
566 signed long
567 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
568                            bool intr, signed long timeout, uint32_t *idx)
569 {
570         struct default_wait_cb *cb;
571         signed long ret = timeout;
572         unsigned i;
573
574         if (WARN_ON(!fences || !count || timeout < 0))
575                 return -EINVAL;
576
577         if (timeout == 0) {
578                 for (i = 0; i < count; ++i)
579                         if (dma_fence_is_signaled(fences[i])) {
580                                 if (idx)
581                                         *idx = i;
582                                 return 1;
583                         }
584
585                 return 0;
586         }
587
588         cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
589         if (cb == NULL) {
590                 ret = -ENOMEM;
591                 goto err_free_cb;
592         }
593
594         for (i = 0; i < count; ++i) {
595                 struct dma_fence *fence = fences[i];
596
597                 cb[i].task = current;
598                 if (dma_fence_add_callback(fence, &cb[i].base,
599                                            dma_fence_default_wait_cb)) {
600                         /* This fence is already signaled */
601                         if (idx)
602                                 *idx = i;
603                         goto fence_rm_cb;
604                 }
605         }
606
607         while (ret > 0) {
608                 if (intr)
609                         set_current_state(TASK_INTERRUPTIBLE);
610                 else
611                         set_current_state(TASK_UNINTERRUPTIBLE);
612
613                 if (dma_fence_test_signaled_any(fences, count, idx))
614                         break;
615
616                 ret = schedule_timeout(ret);
617
618                 if (ret > 0 && intr && signal_pending(current))
619                         ret = -ERESTARTSYS;
620         }
621
622         __set_current_state(TASK_RUNNING);
623
624 fence_rm_cb:
625         while (i-- > 0)
626                 dma_fence_remove_callback(fences[i], &cb[i].base);
627
628 err_free_cb:
629         kfree(cb);
630
631         return ret;
632 }
633 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
634
635 /**
636  * dma_fence_init - Initialize a custom fence.
637  * @fence: the fence to initialize
638  * @ops: the dma_fence_ops for operations on this fence
639  * @lock: the irqsafe spinlock to use for locking this fence
640  * @context: the execution context this fence is run on
641  * @seqno: a linear increasing sequence number for this context
642  *
643  * Initializes an allocated fence, the caller doesn't have to keep its
644  * refcount after committing with this fence, but it will need to hold a
645  * refcount again if &dma_fence_ops.enable_signaling gets called.
646  *
647  * context and seqno are used for easy comparison between fences, allowing
648  * to check which fence is later by simply using dma_fence_later().
649  */
650 void
651 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
652                spinlock_t *lock, u64 context, u64 seqno)
653 {
654         BUG_ON(!lock);
655         BUG_ON(!ops || !ops->get_driver_name || !ops->get_timeline_name);
656
657         kref_init(&fence->refcount);
658         fence->ops = ops;
659         INIT_LIST_HEAD(&fence->cb_list);
660         fence->lock = lock;
661         fence->context = context;
662         fence->seqno = seqno;
663         fence->flags = 0UL;
664         fence->error = 0;
665
666         trace_dma_fence_init(fence);
667 }
668 EXPORT_SYMBOL(dma_fence_init);