x86/speculation/mds: Fix documentation typo
[linux/fpc-iii.git] / drivers / dma-buf / dma-fence.c
blob9a302799040e4529bc5d08ce7c17343421ea19b6
1 /*
2 * Fence mechanism for dma-buf and to allow for asynchronous dma access
4 * Copyright (C) 2012 Canonical Ltd
5 * Copyright (C) 2012 Texas Instruments
7 * Authors:
8 * Rob Clark <robdclark@gmail.com>
9 * Maarten Lankhorst <maarten.lankhorst@canonical.com>
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.
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.
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>
27 #define CREATE_TRACE_POINTS
28 #include <trace/events/dma_fence.h>
30 EXPORT_TRACEPOINT_SYMBOL(dma_fence_annotate_wait_on);
31 EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit);
32 EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal);
35 * fence context counter: each execution context should have its own
36 * fence context, this allows checking if fences belong to the same
37 * context or not. One device can have multiple separate contexts,
38 * and they're used if some engine can run independently of another.
40 static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0);
42 /**
43 * dma_fence_context_alloc - allocate an array of fence contexts
44 * @num: [in] amount of contexts to allocate
46 * This function will return the first index of the number of fences allocated.
47 * The fence context is used for setting fence->context to a unique number.
49 u64 dma_fence_context_alloc(unsigned num)
51 WARN_ON(!num);
52 return atomic64_add_return(num, &dma_fence_context_counter) - num;
54 EXPORT_SYMBOL(dma_fence_context_alloc);
56 /**
57 * dma_fence_signal_locked - signal completion of a fence
58 * @fence: the fence to signal
60 * Signal completion for software callbacks on a fence, this will unblock
61 * dma_fence_wait() calls and run all the callbacks added with
62 * dma_fence_add_callback(). Can be called multiple times, but since a fence
63 * can only go from unsignaled to signaled state, it will only be effective
64 * the first time.
66 * Unlike dma_fence_signal, this function must be called with fence->lock held.
68 int dma_fence_signal_locked(struct dma_fence *fence)
70 struct dma_fence_cb *cur, *tmp;
71 int ret = 0;
73 lockdep_assert_held(fence->lock);
75 if (WARN_ON(!fence))
76 return -EINVAL;
78 if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
79 ret = -EINVAL;
82 * we might have raced with the unlocked dma_fence_signal,
83 * still run through all callbacks
85 } else {
86 fence->timestamp = ktime_get();
87 set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
88 trace_dma_fence_signaled(fence);
91 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
92 list_del_init(&cur->node);
93 cur->func(fence, cur);
95 return ret;
97 EXPORT_SYMBOL(dma_fence_signal_locked);
99 /**
100 * dma_fence_signal - signal completion of a fence
101 * @fence: the fence to signal
103 * Signal completion for software callbacks on a fence, this will unblock
104 * dma_fence_wait() calls and run all the callbacks added with
105 * dma_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.
109 int dma_fence_signal(struct dma_fence *fence)
111 unsigned long flags;
113 if (!fence)
114 return -EINVAL;
116 if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
117 return -EINVAL;
119 fence->timestamp = ktime_get();
120 set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
121 trace_dma_fence_signaled(fence);
123 if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
124 struct dma_fence_cb *cur, *tmp;
126 spin_lock_irqsave(fence->lock, flags);
127 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
128 list_del_init(&cur->node);
129 cur->func(fence, cur);
131 spin_unlock_irqrestore(fence->lock, flags);
133 return 0;
135 EXPORT_SYMBOL(dma_fence_signal);
138 * dma_fence_wait_timeout - sleep until the fence gets signaled
139 * or until timeout elapses
140 * @fence: [in] the fence to wait on
141 * @intr: [in] if true, do an interruptible wait
142 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
144 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
145 * remaining timeout in jiffies on success. Other error values may be
146 * returned on custom implementations.
148 * Performs a synchronous wait on this fence. It is assumed the caller
149 * directly or indirectly (buf-mgr between reservation and committing)
150 * holds a reference to the fence, otherwise the fence might be
151 * freed before return, resulting in undefined behavior.
153 signed long
154 dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
156 signed long ret;
158 if (WARN_ON(timeout < 0))
159 return -EINVAL;
161 trace_dma_fence_wait_start(fence);
162 ret = fence->ops->wait(fence, intr, timeout);
163 trace_dma_fence_wait_end(fence);
164 return ret;
166 EXPORT_SYMBOL(dma_fence_wait_timeout);
168 void dma_fence_release(struct kref *kref)
170 struct dma_fence *fence =
171 container_of(kref, struct dma_fence, refcount);
173 trace_dma_fence_destroy(fence);
175 WARN_ON(!list_empty(&fence->cb_list));
177 if (fence->ops->release)
178 fence->ops->release(fence);
179 else
180 dma_fence_free(fence);
182 EXPORT_SYMBOL(dma_fence_release);
184 void dma_fence_free(struct dma_fence *fence)
186 kfree_rcu(fence, rcu);
188 EXPORT_SYMBOL(dma_fence_free);
191 * dma_fence_enable_sw_signaling - enable signaling on fence
192 * @fence: [in] the fence to enable
194 * this will request for sw signaling to be enabled, to make the fence
195 * complete as soon as possible
197 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
199 unsigned long flags;
201 if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
202 &fence->flags) &&
203 !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
204 trace_dma_fence_enable_signal(fence);
206 spin_lock_irqsave(fence->lock, flags);
208 if (!fence->ops->enable_signaling(fence))
209 dma_fence_signal_locked(fence);
211 spin_unlock_irqrestore(fence->lock, flags);
214 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
217 * dma_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
223 * cb will be initialized by dma_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.
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)
231 * Add a software callback to the fence. Same restrictions apply to
232 * refcount as it does to dma_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 dma_fence_signal. The callback itself can be called
236 * from irq context.
238 * Returns 0 in case of success, -ENOENT if the fence is already signaled
239 * and -EINVAL in case of error.
241 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
242 dma_fence_func_t func)
244 unsigned long flags;
245 int ret = 0;
246 bool was_set;
248 if (WARN_ON(!fence || !func))
249 return -EINVAL;
251 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
252 INIT_LIST_HEAD(&cb->node);
253 return -ENOENT;
256 spin_lock_irqsave(fence->lock, flags);
258 was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
259 &fence->flags);
261 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
262 ret = -ENOENT;
263 else if (!was_set) {
264 trace_dma_fence_enable_signal(fence);
266 if (!fence->ops->enable_signaling(fence)) {
267 dma_fence_signal_locked(fence);
268 ret = -ENOENT;
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);
279 return ret;
281 EXPORT_SYMBOL(dma_fence_add_callback);
284 * dma_fence_get_status - returns the status upon completion
285 * @fence: [in] the dma_fence to query
287 * This wraps dma_fence_get_status_locked() to return the error status
288 * condition on a signaled fence. See dma_fence_get_status_locked() for more
289 * details.
291 * Returns 0 if the fence has not yet been signaled, 1 if the fence has
292 * been signaled without an error condition, or a negative error code
293 * if the fence has been completed in err.
295 int dma_fence_get_status(struct dma_fence *fence)
297 unsigned long flags;
298 int status;
300 spin_lock_irqsave(fence->lock, flags);
301 status = dma_fence_get_status_locked(fence);
302 spin_unlock_irqrestore(fence->lock, flags);
304 return status;
306 EXPORT_SYMBOL(dma_fence_get_status);
309 * dma_fence_remove_callback - remove a callback from the signaling list
310 * @fence: [in] the fence to wait on
311 * @cb: [in] the callback to remove
313 * Remove a previously queued callback from the fence. This function returns
314 * true if the callback is successfully removed, or false if the fence has
315 * already been signaled.
317 * *WARNING*:
318 * Cancelling a callback should only be done if you really know what you're
319 * doing, since deadlocks and race conditions could occur all too easily. For
320 * this reason, it should only ever be done on hardware lockup recovery,
321 * with a reference held to the fence.
323 bool
324 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
326 unsigned long flags;
327 bool ret;
329 spin_lock_irqsave(fence->lock, flags);
331 ret = !list_empty(&cb->node);
332 if (ret)
333 list_del_init(&cb->node);
335 spin_unlock_irqrestore(fence->lock, flags);
337 return ret;
339 EXPORT_SYMBOL(dma_fence_remove_callback);
341 struct default_wait_cb {
342 struct dma_fence_cb base;
343 struct task_struct *task;
346 static void
347 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
349 struct default_wait_cb *wait =
350 container_of(cb, struct default_wait_cb, base);
352 wake_up_state(wait->task, TASK_NORMAL);
356 * dma_fence_default_wait - default sleep until the fence gets signaled
357 * or until timeout elapses
358 * @fence: [in] the fence to wait on
359 * @intr: [in] if true, do an interruptible wait
360 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
362 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
363 * remaining timeout in jiffies on success. If timeout is zero the value one is
364 * returned if the fence is already signaled for consistency with other
365 * functions taking a jiffies timeout.
367 signed long
368 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
370 struct default_wait_cb cb;
371 unsigned long flags;
372 signed long ret = timeout ? timeout : 1;
373 bool was_set;
375 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
376 return ret;
378 spin_lock_irqsave(fence->lock, flags);
380 if (intr && signal_pending(current)) {
381 ret = -ERESTARTSYS;
382 goto out;
385 was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
386 &fence->flags);
388 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
389 goto out;
391 if (!was_set) {
392 trace_dma_fence_enable_signal(fence);
394 if (!fence->ops->enable_signaling(fence)) {
395 dma_fence_signal_locked(fence);
396 goto out;
400 if (!timeout) {
401 ret = 0;
402 goto out;
405 cb.base.func = dma_fence_default_wait_cb;
406 cb.task = current;
407 list_add(&cb.base.node, &fence->cb_list);
409 while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
410 if (intr)
411 __set_current_state(TASK_INTERRUPTIBLE);
412 else
413 __set_current_state(TASK_UNINTERRUPTIBLE);
414 spin_unlock_irqrestore(fence->lock, flags);
416 ret = schedule_timeout(ret);
418 spin_lock_irqsave(fence->lock, flags);
419 if (ret > 0 && intr && signal_pending(current))
420 ret = -ERESTARTSYS;
423 if (!list_empty(&cb.base.node))
424 list_del(&cb.base.node);
425 __set_current_state(TASK_RUNNING);
427 out:
428 spin_unlock_irqrestore(fence->lock, flags);
429 return ret;
431 EXPORT_SYMBOL(dma_fence_default_wait);
433 static bool
434 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
435 uint32_t *idx)
437 int i;
439 for (i = 0; i < count; ++i) {
440 struct dma_fence *fence = fences[i];
441 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
442 if (idx)
443 *idx = i;
444 return true;
447 return false;
451 * dma_fence_wait_any_timeout - sleep until any fence gets signaled
452 * or until timeout elapses
453 * @fences: [in] array of fences to wait on
454 * @count: [in] number of fences to wait on
455 * @intr: [in] if true, do an interruptible wait
456 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
457 * @idx: [out] the first signaled fence index, meaningful only on
458 * positive return
460 * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
461 * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
462 * on success.
464 * Synchronous waits for the first fence in the array to be signaled. The
465 * caller needs to hold a reference to all fences in the array, otherwise a
466 * fence might be freed before return, resulting in undefined behavior.
468 signed long
469 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
470 bool intr, signed long timeout, uint32_t *idx)
472 struct default_wait_cb *cb;
473 signed long ret = timeout;
474 unsigned i;
476 if (WARN_ON(!fences || !count || timeout < 0))
477 return -EINVAL;
479 if (timeout == 0) {
480 for (i = 0; i < count; ++i)
481 if (dma_fence_is_signaled(fences[i])) {
482 if (idx)
483 *idx = i;
484 return 1;
487 return 0;
490 cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
491 if (cb == NULL) {
492 ret = -ENOMEM;
493 goto err_free_cb;
496 for (i = 0; i < count; ++i) {
497 struct dma_fence *fence = fences[i];
499 if (fence->ops->wait != dma_fence_default_wait) {
500 ret = -EINVAL;
501 goto fence_rm_cb;
504 cb[i].task = current;
505 if (dma_fence_add_callback(fence, &cb[i].base,
506 dma_fence_default_wait_cb)) {
507 /* This fence is already signaled */
508 if (idx)
509 *idx = i;
510 goto fence_rm_cb;
514 while (ret > 0) {
515 if (intr)
516 set_current_state(TASK_INTERRUPTIBLE);
517 else
518 set_current_state(TASK_UNINTERRUPTIBLE);
520 if (dma_fence_test_signaled_any(fences, count, idx))
521 break;
523 ret = schedule_timeout(ret);
525 if (ret > 0 && intr && signal_pending(current))
526 ret = -ERESTARTSYS;
529 __set_current_state(TASK_RUNNING);
531 fence_rm_cb:
532 while (i-- > 0)
533 dma_fence_remove_callback(fences[i], &cb[i].base);
535 err_free_cb:
536 kfree(cb);
538 return ret;
540 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
543 * dma_fence_init - Initialize a custom fence.
544 * @fence: [in] the fence to initialize
545 * @ops: [in] the dma_fence_ops for operations on this fence
546 * @lock: [in] the irqsafe spinlock to use for locking this fence
547 * @context: [in] the execution context this fence is run on
548 * @seqno: [in] a linear increasing sequence number for this context
550 * Initializes an allocated fence, the caller doesn't have to keep its
551 * refcount after committing with this fence, but it will need to hold a
552 * refcount again if dma_fence_ops.enable_signaling gets called. This can
553 * be used for other implementing other types of fence.
555 * context and seqno are used for easy comparison between fences, allowing
556 * to check which fence is later by simply using dma_fence_later.
558 void
559 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
560 spinlock_t *lock, u64 context, unsigned seqno)
562 BUG_ON(!lock);
563 BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
564 !ops->get_driver_name || !ops->get_timeline_name);
566 kref_init(&fence->refcount);
567 fence->ops = ops;
568 INIT_LIST_HEAD(&fence->cb_list);
569 fence->lock = lock;
570 fence->context = context;
571 fence->seqno = seqno;
572 fence->flags = 0UL;
573 fence->error = 0;
575 trace_dma_fence_init(fence);
577 EXPORT_SYMBOL(dma_fence_init);