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
);