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
243 * Returns 0 in case of success, -ENOENT if the fence is already signaled
244 * and -EINVAL in case of error.
246 int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
247 dma_fence_func_t func)
253 if (WARN_ON(!fence || !func))
256 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
257 INIT_LIST_HEAD(&cb->node);
261 spin_lock_irqsave(fence->lock, flags);
263 was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
266 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
269 trace_dma_fence_enable_signal(fence);
271 if (!fence->ops->enable_signaling(fence)) {
272 dma_fence_signal_locked(fence);
279 list_add_tail(&cb->node, &fence->cb_list);
281 INIT_LIST_HEAD(&cb->node);
282 spin_unlock_irqrestore(fence->lock, flags);
286 EXPORT_SYMBOL(dma_fence_add_callback);
289 * dma_fence_get_status - returns the status upon completion
290 * @fence: [in] the dma_fence to query
292 * This wraps dma_fence_get_status_locked() to return the error status
293 * condition on a signaled fence. See dma_fence_get_status_locked() for more
296 * Returns 0 if the fence has not yet been signaled, 1 if the fence has
297 * been signaled without an error condition, or a negative error code
298 * if the fence has been completed in err.
300 int dma_fence_get_status(struct dma_fence *fence)
305 spin_lock_irqsave(fence->lock, flags);
306 status = dma_fence_get_status_locked(fence);
307 spin_unlock_irqrestore(fence->lock, flags);
311 EXPORT_SYMBOL(dma_fence_get_status);
314 * dma_fence_remove_callback - remove a callback from the signaling list
315 * @fence: [in] the fence to wait on
316 * @cb: [in] the callback to remove
318 * Remove a previously queued callback from the fence. This function returns
319 * true if the callback is successfully removed, or false if the fence has
320 * already been signaled.
323 * Cancelling a callback should only be done if you really know what you're
324 * doing, since deadlocks and race conditions could occur all too easily. For
325 * this reason, it should only ever be done on hardware lockup recovery,
326 * with a reference held to the fence.
329 dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
334 spin_lock_irqsave(fence->lock, flags);
336 ret = !list_empty(&cb->node);
338 list_del_init(&cb->node);
340 spin_unlock_irqrestore(fence->lock, flags);
344 EXPORT_SYMBOL(dma_fence_remove_callback);
346 struct default_wait_cb {
347 struct dma_fence_cb base;
348 struct task_struct *task;
352 dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
354 struct default_wait_cb *wait =
355 container_of(cb, struct default_wait_cb, base);
357 wake_up_state(wait->task, TASK_NORMAL);
361 * dma_fence_default_wait - default sleep until the fence gets signaled
362 * or until timeout elapses
363 * @fence: [in] the fence to wait on
364 * @intr: [in] if true, do an interruptible wait
365 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
367 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
368 * remaining timeout in jiffies on success. If timeout is zero the value one is
369 * returned if the fence is already signaled for consistency with other
370 * functions taking a jiffies timeout.
373 dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
375 struct default_wait_cb cb;
377 signed long ret = timeout ? timeout : 1;
380 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
383 spin_lock_irqsave(fence->lock, flags);
385 if (intr && signal_pending(current)) {
390 was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
393 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
397 trace_dma_fence_enable_signal(fence);
399 if (!fence->ops->enable_signaling(fence)) {
400 dma_fence_signal_locked(fence);
410 cb.base.func = dma_fence_default_wait_cb;
412 list_add(&cb.base.node, &fence->cb_list);
414 while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
416 __set_current_state(TASK_INTERRUPTIBLE);
418 __set_current_state(TASK_UNINTERRUPTIBLE);
419 spin_unlock_irqrestore(fence->lock, flags);
421 ret = schedule_timeout(ret);
423 spin_lock_irqsave(fence->lock, flags);
424 if (ret > 0 && intr && signal_pending(current))
428 if (!list_empty(&cb.base.node))
429 list_del(&cb.base.node);
430 __set_current_state(TASK_RUNNING);
433 spin_unlock_irqrestore(fence->lock, flags);
436 EXPORT_SYMBOL(dma_fence_default_wait);
439 dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
444 for (i = 0; i < count; ++i) {
445 struct dma_fence *fence = fences[i];
446 if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
456 * dma_fence_wait_any_timeout - sleep until any fence gets signaled
457 * or until timeout elapses
458 * @fences: [in] array of fences to wait on
459 * @count: [in] number of fences to wait on
460 * @intr: [in] if true, do an interruptible wait
461 * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
462 * @idx: [out] the first signaled fence index, meaningful only on
465 * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
466 * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
469 * Synchronous waits for the first fence in the array to be signaled. The
470 * caller needs to hold a reference to all fences in the array, otherwise a
471 * fence might be freed before return, resulting in undefined behavior.
474 dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
475 bool intr, signed long timeout, uint32_t *idx)
477 struct default_wait_cb *cb;
478 signed long ret = timeout;
481 if (WARN_ON(!fences || !count || timeout < 0))
485 for (i = 0; i < count; ++i)
486 if (dma_fence_is_signaled(fences[i])) {
495 cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL);
501 for (i = 0; i < count; ++i) {
502 struct dma_fence *fence = fences[i];
504 if (fence->ops->wait != dma_fence_default_wait) {
509 cb[i].task = current;
510 if (dma_fence_add_callback(fence, &cb[i].base,
511 dma_fence_default_wait_cb)) {
512 /* This fence is already signaled */
521 set_current_state(TASK_INTERRUPTIBLE);
523 set_current_state(TASK_UNINTERRUPTIBLE);
525 if (dma_fence_test_signaled_any(fences, count, idx))
528 ret = schedule_timeout(ret);
530 if (ret > 0 && intr && signal_pending(current))
534 __set_current_state(TASK_RUNNING);
538 dma_fence_remove_callback(fences[i], &cb[i].base);
545 EXPORT_SYMBOL(dma_fence_wait_any_timeout);
548 * dma_fence_init - Initialize a custom fence.
549 * @fence: [in] the fence to initialize
550 * @ops: [in] the dma_fence_ops for operations on this fence
551 * @lock: [in] the irqsafe spinlock to use for locking this fence
552 * @context: [in] the execution context this fence is run on
553 * @seqno: [in] a linear increasing sequence number for this context
555 * Initializes an allocated fence, the caller doesn't have to keep its
556 * refcount after committing with this fence, but it will need to hold a
557 * refcount again if dma_fence_ops.enable_signaling gets called. This can
558 * be used for other implementing other types of fence.
560 * context and seqno are used for easy comparison between fences, allowing
561 * to check which fence is later by simply using dma_fence_later.
564 dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
565 spinlock_t *lock, u64 context, unsigned seqno)
568 BUG_ON(!ops || !ops->wait || !ops->enable_signaling ||
569 !ops->get_driver_name || !ops->get_timeline_name);
571 kref_init(&fence->refcount);
573 INIT_LIST_HEAD(&fence->cb_list);
575 fence->context = context;
576 fence->seqno = seqno;
580 trace_dma_fence_init(fence);
582 EXPORT_SYMBOL(dma_fence_init);