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
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
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);
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)
52 return atomic64_add_return(num, &dma_fence_context_counter) - num;
54 EXPORT_SYMBOL(dma_fence_context_alloc);
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
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;
73 lockdep_assert_held(fence->lock);
78 if (!ktime_to_ns(fence->timestamp)) {
79 fence->timestamp = ktime_get();
80 smp_mb__before_atomic();
83 if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
87 * we might have raced with the unlocked dma_fence_signal,
88 * still run through all callbacks
91 trace_dma_fence_signaled(fence);
93 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
94 list_del_init(&cur->node);
95 cur->func(fence, cur);
99 EXPORT_SYMBOL(dma_fence_signal_locked);
102 * dma_fence_signal - signal completion of a fence
103 * @fence: the fence to signal
105 * Signal completion for software callbacks on a fence, this will unblock
106 * dma_fence_wait() calls and run all the callbacks added with
107 * dma_fence_add_callback(). Can be called multiple times, but since a fence
108 * can only go from unsignaled to signaled state, it will only be effective
111 int dma_fence_signal(struct dma_fence *fence)
118 if (!ktime_to_ns(fence->timestamp)) {
119 fence->timestamp = ktime_get();
120 smp_mb__before_atomic();
123 if (test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
126 trace_dma_fence_signaled(fence);
128 if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags)) {
129 struct dma_fence_cb *cur, *tmp;
131 spin_lock_irqsave(fence->lock, flags);
132 list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
133 list_del_init(&cur->node);
134 cur->func(fence, cur);
136 spin_unlock_irqrestore(fence->lock, flags);
140 EXPORT_SYMBOL(dma_fence_signal);
143 * dma_fence_wait_timeout - sleep until the fence gets signaled
144 * or until timeout elapses
145 * @fence: [in] the fence to wait on
146 * @intr: [in] if true, do an interruptible wait
147 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
149 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
150 * remaining timeout in jiffies on success. Other error values may be
151 * returned on custom implementations.
153 * Performs a synchronous wait on this fence. It is assumed the caller
154 * directly or indirectly (buf-mgr between reservation and committing)
155 * holds a reference to the fence, otherwise the fence might be
156 * freed before return, resulting in undefined behavior.
159 dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
163 if (WARN_ON(timeout < 0))
166 trace_dma_fence_wait_start(fence);
167 ret = fence->ops->wait(fence, intr, timeout);
168 trace_dma_fence_wait_end(fence);
171 EXPORT_SYMBOL(dma_fence_wait_timeout);
173 void dma_fence_release(struct kref *kref)
175 struct dma_fence *fence =
176 container_of(kref, struct dma_fence, refcount);
178 trace_dma_fence_destroy(fence);
180 BUG_ON(!list_empty(&fence->cb_list));
182 if (fence->ops->release)
183 fence->ops->release(fence);
185 dma_fence_free(fence);
187 EXPORT_SYMBOL(dma_fence_release);
189 void dma_fence_free(struct dma_fence *fence)
191 kfree_rcu(fence, rcu);
193 EXPORT_SYMBOL(dma_fence_free);
196 * dma_fence_enable_sw_signaling - enable signaling on fence
197 * @fence: [in] the fence to enable
199 * this will request for sw signaling to be enabled, to make the fence
200 * complete as soon as possible
202 void dma_fence_enable_sw_signaling(struct dma_fence *fence)
206 if (!test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
208 !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
209 trace_dma_fence_enable_signal(fence);
211 spin_lock_irqsave(fence->lock, flags);
213 if (!fence->ops->enable_signaling(fence))
214 dma_fence_signal_locked(fence);
216 spin_unlock_irqrestore(fence->lock, flags);
219 EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
222 * dma_fence_add_callback - add a callback to be called when the fence
224 * @fence: [in] the fence to wait on
225 * @cb: [in] the callback to register
226 * @func: [in] the function to call
228 * cb will be initialized by dma_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.
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)
236 * Add a software callback to the fence. Same restrictions apply to
237 * refcount as it does to dma_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 dma_fence_signal. The callback itself can be called
244 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
245 dma_fence_func_t func)
251 if (WARN_ON(!fence || !func))
254 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
255 INIT_LIST_HEAD(&cb->node);
259 spin_lock_irqsave(fence->lock, flags);
261 was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
264 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
267 trace_dma_fence_enable_signal(fence);
269 if (!fence->ops->enable_signaling(fence)) {
270 dma_fence_signal_locked(fence);
277 list_add_tail(&cb->node, &fence->cb_list);
279 INIT_LIST_HEAD(&cb->node);
280 spin_unlock_irqrestore(fence->lock, flags);
284 EXPORT_SYMBOL(dma_fence_add_callback);
287 * dma_fence_get_status - returns the status upon completion
288 * @fence: [in] the dma_fence to query
290 * This wraps dma_fence_get_status_locked() to return the error status
291 * condition on a signaled fence. See dma_fence_get_status_locked() for more
294 * Returns 0 if the fence has not yet been signaled, 1 if the fence has
295 * been signaled without an error condition, or a negative error code
296 * if the fence has been completed in err.
298 int dma_fence_get_status(struct dma_fence *fence)
303 spin_lock_irqsave(fence->lock, flags);
304 status = dma_fence_get_status_locked(fence);
305 spin_unlock_irqrestore(fence->lock, flags);
309 EXPORT_SYMBOL(dma_fence_get_status);
312 * dma_fence_remove_callback - remove a callback from the signaling list
313 * @fence: [in] the fence to wait on
314 * @cb: [in] the callback to remove
316 * Remove a previously queued callback from the fence. This function returns
317 * true if the callback is successfully removed, or false if the fence has
318 * already been signaled.
321 * Cancelling a callback should only be done if you really know what you're
322 * doing, since deadlocks and race conditions could occur all too easily. For
323 * this reason, it should only ever be done on hardware lockup recovery,
324 * with a reference held to the fence.
327 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
332 spin_lock_irqsave(fence->lock, flags);
334 ret = !list_empty(&cb->node);
336 list_del_init(&cb->node);
338 spin_unlock_irqrestore(fence->lock, flags);
342 EXPORT_SYMBOL(dma_fence_remove_callback);
344 struct default_wait_cb {
345 struct dma_fence_cb base;
346 struct task_struct *task;
350 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
352 struct default_wait_cb *wait =
353 container_of(cb, struct default_wait_cb, base);
355 wake_up_state(wait->task, TASK_NORMAL);
359 * dma_fence_default_wait - default sleep until the fence gets signaled
360 * or until timeout elapses
361 * @fence: [in] the fence to wait on
362 * @intr: [in] if true, do an interruptible wait
363 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
365 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
366 * remaining timeout in jiffies on success. If timeout is zero the value one is
367 * returned if the fence is already signaled for consistency with other
368 * functions taking a jiffies timeout.
371 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
373 struct default_wait_cb cb;
375 signed long ret = timeout ? timeout : 1;
378 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
381 spin_lock_irqsave(fence->lock, flags);
383 if (intr && signal_pending(current)) {
388 was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
391 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
395 trace_dma_fence_enable_signal(fence);
397 if (!fence->ops->enable_signaling(fence)) {
398 dma_fence_signal_locked(fence);
403 cb.base.func = dma_fence_default_wait_cb;
405 list_add(&cb.base.node, &fence->cb_list);
407 while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
409 __set_current_state(TASK_INTERRUPTIBLE);
411 __set_current_state(TASK_UNINTERRUPTIBLE);
412 spin_unlock_irqrestore(fence->lock, flags);
414 ret = schedule_timeout(ret);
416 spin_lock_irqsave(fence->lock, flags);
417 if (ret > 0 && intr && signal_pending(current))
421 if (!list_empty(&cb.base.node))
422 list_del(&cb.base.node);
423 __set_current_state(TASK_RUNNING);
426 spin_unlock_irqrestore(fence->lock, flags);
429 EXPORT_SYMBOL(dma_fence_default_wait);
432 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
437 for (i = 0; i < count; ++i) {
438 struct dma_fence *fence = fences[i];
439 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
449 * dma_fence_wait_any_timeout - sleep until any fence gets signaled
450 * or until timeout elapses
451 * @fences: [in] array of fences to wait on
452 * @count: [in] number of fences to wait on
453 * @intr: [in] if true, do an interruptible wait
454 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
455 * @idx: [out] the first signaled fence index, meaningful only on
458 * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
459 * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
462 * Synchronous waits for the first fence in the array to be signaled. The
463 * caller needs to hold a reference to all fences in the array, otherwise a
464 * fence might be freed before return, resulting in undefined behavior.
467 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
468 bool intr, signed long timeout, uint32_t *idx)
470 struct default_wait_cb *cb;
471 signed long ret = timeout;
474 if (WARN_ON(!fences || !count || timeout < 0))
478 for (i = 0; i < count; ++i)
479 if (dma_fence_is_signaled(fences[i])) {
488 cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
494 for (i = 0; i < count; ++i) {
495 struct dma_fence *fence = fences[i];
497 if (fence->ops->wait != dma_fence_default_wait) {
502 cb[i].task = current;
503 if (dma_fence_add_callback(fence, &cb[i].base,
504 dma_fence_default_wait_cb)) {
505 /* This fence is already signaled */
514 set_current_state(TASK_INTERRUPTIBLE);
516 set_current_state(TASK_UNINTERRUPTIBLE);
518 if (dma_fence_test_signaled_any(fences, count, idx))
521 ret = schedule_timeout(ret);
523 if (ret > 0 && intr && signal_pending(current))
527 __set_current_state(TASK_RUNNING);
531 dma_fence_remove_callback(fences[i], &cb[i].base);
538 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
541 * dma_fence_init - Initialize a custom fence.
542 * @fence: [in] the fence to initialize
543 * @ops: [in] the dma_fence_ops for operations on this fence
544 * @lock: [in] the irqsafe spinlock to use for locking this fence
545 * @context: [in] the execution context this fence is run on
546 * @seqno: [in] a linear increasing sequence number for this context
548 * Initializes an allocated fence, the caller doesn't have to keep its
549 * refcount after committing with this fence, but it will need to hold a
550 * refcount again if dma_fence_ops.enable_signaling gets called. This can
551 * be used for other implementing other types of fence.
553 * context and seqno are used for easy comparison between fences, allowing
554 * to check which fence is later by simply using dma_fence_later.
557 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
558 spinlock_t *lock, u64 context, unsigned seqno)
561 BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
562 !ops->get_driver_name || !ops->get_timeline_name);
564 kref_init(&fence->refcount);
566 INIT_LIST_HEAD(&fence->cb_list);
568 fence->context = context;
569 fence->seqno = seqno;
573 trace_dma_fence_init(fence);
575 EXPORT_SYMBOL(dma_fence_init);