Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0-only */
2 : /*
3 : * Fence mechanism for dma-buf to allow for asynchronous dma access
4 : *
5 : * Copyright (C) 2012 Canonical Ltd
6 : * Copyright (C) 2012 Texas Instruments
7 : *
8 : * Authors:
9 : * Rob Clark <robdclark@gmail.com>
10 : * Maarten Lankhorst <maarten.lankhorst@canonical.com>
11 : */
12 :
13 : #ifndef __LINUX_DMA_FENCE_H
14 : #define __LINUX_DMA_FENCE_H
15 :
16 : #include <linux/err.h>
17 : #include <linux/wait.h>
18 : #include <linux/list.h>
19 : #include <linux/bitops.h>
20 : #include <linux/kref.h>
21 : #include <linux/sched.h>
22 : #include <linux/printk.h>
23 : #include <linux/rcupdate.h>
24 :
25 : struct dma_fence;
26 : struct dma_fence_ops;
27 : struct dma_fence_cb;
28 :
29 : /**
30 : * struct dma_fence - software synchronization primitive
31 : * @refcount: refcount for this fence
32 : * @ops: dma_fence_ops associated with this fence
33 : * @rcu: used for releasing fence with kfree_rcu
34 : * @cb_list: list of all callbacks to call
35 : * @lock: spin_lock_irqsave used for locking
36 : * @context: execution context this fence belongs to, returned by
37 : * dma_fence_context_alloc()
38 : * @seqno: the sequence number of this fence inside the execution context,
39 : * can be compared to decide which fence would be signaled later.
40 : * @flags: A mask of DMA_FENCE_FLAG_* defined below
41 : * @timestamp: Timestamp when the fence was signaled.
42 : * @error: Optional, only valid if < 0, must be set before calling
43 : * dma_fence_signal, indicates that the fence has completed with an error.
44 : *
45 : * the flags member must be manipulated and read using the appropriate
46 : * atomic ops (bit_*), so taking the spinlock will not be needed most
47 : * of the time.
48 : *
49 : * DMA_FENCE_FLAG_SIGNALED_BIT - fence is already signaled
50 : * DMA_FENCE_FLAG_TIMESTAMP_BIT - timestamp recorded for fence signaling
51 : * DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT - enable_signaling might have been called
52 : * DMA_FENCE_FLAG_USER_BITS - start of the unused bits, can be used by the
53 : * implementer of the fence for its own purposes. Can be used in different
54 : * ways by different fence implementers, so do not rely on this.
55 : *
56 : * Since atomic bitops are used, this is not guaranteed to be the case.
57 : * Particularly, if the bit was set, but dma_fence_signal was called right
58 : * before this bit was set, it would have been able to set the
59 : * DMA_FENCE_FLAG_SIGNALED_BIT, before enable_signaling was called.
60 : * Adding a check for DMA_FENCE_FLAG_SIGNALED_BIT after setting
61 : * DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT closes this race, and makes sure that
62 : * after dma_fence_signal was called, any enable_signaling call will have either
63 : * been completed, or never called at all.
64 : */
65 : struct dma_fence {
66 : spinlock_t *lock;
67 : const struct dma_fence_ops *ops;
68 : /*
69 : * We clear the callback list on kref_put so that by the time we
70 : * release the fence it is unused. No one should be adding to the
71 : * cb_list that they don't themselves hold a reference for.
72 : *
73 : * The lifetime of the timestamp is similarly tied to both the
74 : * rcu freelist and the cb_list. The timestamp is only set upon
75 : * signaling while simultaneously notifying the cb_list. Ergo, we
76 : * only use either the cb_list of timestamp. Upon destruction,
77 : * neither are accessible, and so we can use the rcu. This means
78 : * that the cb_list is *only* valid until the signal bit is set,
79 : * and to read either you *must* hold a reference to the fence,
80 : * and not just the rcu_read_lock.
81 : *
82 : * Listed in chronological order.
83 : */
84 : union {
85 : struct list_head cb_list;
86 : /* @cb_list replaced by @timestamp on dma_fence_signal() */
87 : ktime_t timestamp;
88 : /* @timestamp replaced by @rcu on dma_fence_release() */
89 : struct rcu_head rcu;
90 : };
91 : u64 context;
92 : u64 seqno;
93 : unsigned long flags;
94 : struct kref refcount;
95 : int error;
96 : };
97 :
98 : enum dma_fence_flag_bits {
99 : DMA_FENCE_FLAG_SIGNALED_BIT,
100 : DMA_FENCE_FLAG_TIMESTAMP_BIT,
101 : DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
102 : DMA_FENCE_FLAG_USER_BITS, /* must always be last member */
103 : };
104 :
105 : typedef void (*dma_fence_func_t)(struct dma_fence *fence,
106 : struct dma_fence_cb *cb);
107 :
108 : /**
109 : * struct dma_fence_cb - callback for dma_fence_add_callback()
110 : * @node: used by dma_fence_add_callback() to append this struct to fence::cb_list
111 : * @func: dma_fence_func_t to call
112 : *
113 : * This struct will be initialized by dma_fence_add_callback(), additional
114 : * data can be passed along by embedding dma_fence_cb in another struct.
115 : */
116 : struct dma_fence_cb {
117 : struct list_head node;
118 : dma_fence_func_t func;
119 : };
120 :
121 : /**
122 : * struct dma_fence_ops - operations implemented for fence
123 : *
124 : */
125 : struct dma_fence_ops {
126 : /**
127 : * @use_64bit_seqno:
128 : *
129 : * True if this dma_fence implementation uses 64bit seqno, false
130 : * otherwise.
131 : */
132 : bool use_64bit_seqno;
133 :
134 : /**
135 : * @get_driver_name:
136 : *
137 : * Returns the driver name. This is a callback to allow drivers to
138 : * compute the name at runtime, without having it to store permanently
139 : * for each fence, or build a cache of some sort.
140 : *
141 : * This callback is mandatory.
142 : */
143 : const char * (*get_driver_name)(struct dma_fence *fence);
144 :
145 : /**
146 : * @get_timeline_name:
147 : *
148 : * Return the name of the context this fence belongs to. This is a
149 : * callback to allow drivers to compute the name at runtime, without
150 : * having it to store permanently for each fence, or build a cache of
151 : * some sort.
152 : *
153 : * This callback is mandatory.
154 : */
155 : const char * (*get_timeline_name)(struct dma_fence *fence);
156 :
157 : /**
158 : * @enable_signaling:
159 : *
160 : * Enable software signaling of fence.
161 : *
162 : * For fence implementations that have the capability for hw->hw
163 : * signaling, they can implement this op to enable the necessary
164 : * interrupts, or insert commands into cmdstream, etc, to avoid these
165 : * costly operations for the common case where only hw->hw
166 : * synchronization is required. This is called in the first
167 : * dma_fence_wait() or dma_fence_add_callback() path to let the fence
168 : * implementation know that there is another driver waiting on the
169 : * signal (ie. hw->sw case).
170 : *
171 : * This function can be called from atomic context, but not
172 : * from irq context, so normal spinlocks can be used.
173 : *
174 : * A return value of false indicates the fence already passed,
175 : * or some failure occurred that made it impossible to enable
176 : * signaling. True indicates successful enabling.
177 : *
178 : * &dma_fence.error may be set in enable_signaling, but only when false
179 : * is returned.
180 : *
181 : * Since many implementations can call dma_fence_signal() even when before
182 : * @enable_signaling has been called there's a race window, where the
183 : * dma_fence_signal() might result in the final fence reference being
184 : * released and its memory freed. To avoid this, implementations of this
185 : * callback should grab their own reference using dma_fence_get(), to be
186 : * released when the fence is signalled (through e.g. the interrupt
187 : * handler).
188 : *
189 : * This callback is optional. If this callback is not present, then the
190 : * driver must always have signaling enabled.
191 : */
192 : bool (*enable_signaling)(struct dma_fence *fence);
193 :
194 : /**
195 : * @signaled:
196 : *
197 : * Peek whether the fence is signaled, as a fastpath optimization for
198 : * e.g. dma_fence_wait() or dma_fence_add_callback(). Note that this
199 : * callback does not need to make any guarantees beyond that a fence
200 : * once indicates as signalled must always return true from this
201 : * callback. This callback may return false even if the fence has
202 : * completed already, in this case information hasn't propogated throug
203 : * the system yet. See also dma_fence_is_signaled().
204 : *
205 : * May set &dma_fence.error if returning true.
206 : *
207 : * This callback is optional.
208 : */
209 : bool (*signaled)(struct dma_fence *fence);
210 :
211 : /**
212 : * @wait:
213 : *
214 : * Custom wait implementation, defaults to dma_fence_default_wait() if
215 : * not set.
216 : *
217 : * Deprecated and should not be used by new implementations. Only used
218 : * by existing implementations which need special handling for their
219 : * hardware reset procedure.
220 : *
221 : * Must return -ERESTARTSYS if the wait is intr = true and the wait was
222 : * interrupted, and remaining jiffies if fence has signaled, or 0 if wait
223 : * timed out. Can also return other error values on custom implementations,
224 : * which should be treated as if the fence is signaled. For example a hardware
225 : * lockup could be reported like that.
226 : */
227 : signed long (*wait)(struct dma_fence *fence,
228 : bool intr, signed long timeout);
229 :
230 : /**
231 : * @release:
232 : *
233 : * Called on destruction of fence to release additional resources.
234 : * Can be called from irq context. This callback is optional. If it is
235 : * NULL, then dma_fence_free() is instead called as the default
236 : * implementation.
237 : */
238 : void (*release)(struct dma_fence *fence);
239 :
240 : /**
241 : * @fence_value_str:
242 : *
243 : * Callback to fill in free-form debug info specific to this fence, like
244 : * the sequence number.
245 : *
246 : * This callback is optional.
247 : */
248 : void (*fence_value_str)(struct dma_fence *fence, char *str, int size);
249 :
250 : /**
251 : * @timeline_value_str:
252 : *
253 : * Fills in the current value of the timeline as a string, like the
254 : * sequence number. Note that the specific fence passed to this function
255 : * should not matter, drivers should only use it to look up the
256 : * corresponding timeline structures.
257 : */
258 : void (*timeline_value_str)(struct dma_fence *fence,
259 : char *str, int size);
260 :
261 : /**
262 : * @set_deadline:
263 : *
264 : * Callback to allow a fence waiter to inform the fence signaler of
265 : * an upcoming deadline, such as vblank, by which point the waiter
266 : * would prefer the fence to be signaled by. This is intended to
267 : * give feedback to the fence signaler to aid in power management
268 : * decisions, such as boosting GPU frequency.
269 : *
270 : * This is called without &dma_fence.lock held, it can be called
271 : * multiple times and from any context. Locking is up to the callee
272 : * if it has some state to manage. If multiple deadlines are set,
273 : * the expectation is to track the soonest one. If the deadline is
274 : * before the current time, it should be interpreted as an immediate
275 : * deadline.
276 : *
277 : * This callback is optional.
278 : */
279 : void (*set_deadline)(struct dma_fence *fence, ktime_t deadline);
280 : };
281 :
282 : void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
283 : spinlock_t *lock, u64 context, u64 seqno);
284 :
285 : void dma_fence_release(struct kref *kref);
286 : void dma_fence_free(struct dma_fence *fence);
287 : void dma_fence_describe(struct dma_fence *fence, struct seq_file *seq);
288 :
289 : /**
290 : * dma_fence_put - decreases refcount of the fence
291 : * @fence: fence to reduce refcount of
292 : */
293 : static inline void dma_fence_put(struct dma_fence *fence)
294 : {
295 0 : if (fence)
296 0 : kref_put(&fence->refcount, dma_fence_release);
297 : }
298 :
299 : /**
300 : * dma_fence_get - increases refcount of the fence
301 : * @fence: fence to increase refcount of
302 : *
303 : * Returns the same fence, with refcount increased by 1.
304 : */
305 : static inline struct dma_fence *dma_fence_get(struct dma_fence *fence)
306 : {
307 0 : if (fence)
308 0 : kref_get(&fence->refcount);
309 : return fence;
310 : }
311 :
312 : /**
313 : * dma_fence_get_rcu - get a fence from a dma_resv_list with
314 : * rcu read lock
315 : * @fence: fence to increase refcount of
316 : *
317 : * Function returns NULL if no refcount could be obtained, or the fence.
318 : */
319 : static inline struct dma_fence *dma_fence_get_rcu(struct dma_fence *fence)
320 : {
321 0 : if (kref_get_unless_zero(&fence->refcount))
322 : return fence;
323 : else
324 : return NULL;
325 : }
326 :
327 : /**
328 : * dma_fence_get_rcu_safe - acquire a reference to an RCU tracked fence
329 : * @fencep: pointer to fence to increase refcount of
330 : *
331 : * Function returns NULL if no refcount could be obtained, or the fence.
332 : * This function handles acquiring a reference to a fence that may be
333 : * reallocated within the RCU grace period (such as with SLAB_TYPESAFE_BY_RCU),
334 : * so long as the caller is using RCU on the pointer to the fence.
335 : *
336 : * An alternative mechanism is to employ a seqlock to protect a bunch of
337 : * fences, such as used by struct dma_resv. When using a seqlock,
338 : * the seqlock must be taken before and checked after a reference to the
339 : * fence is acquired (as shown here).
340 : *
341 : * The caller is required to hold the RCU read lock.
342 : */
343 : static inline struct dma_fence *
344 0 : dma_fence_get_rcu_safe(struct dma_fence __rcu **fencep)
345 : {
346 : do {
347 : struct dma_fence *fence;
348 :
349 0 : fence = rcu_dereference(*fencep);
350 0 : if (!fence)
351 : return NULL;
352 :
353 0 : if (!dma_fence_get_rcu(fence))
354 0 : continue;
355 :
356 : /* The atomic_inc_not_zero() inside dma_fence_get_rcu()
357 : * provides a full memory barrier upon success (such as now).
358 : * This is paired with the write barrier from assigning
359 : * to the __rcu protected fence pointer so that if that
360 : * pointer still matches the current fence, we know we
361 : * have successfully acquire a reference to it. If it no
362 : * longer matches, we are holding a reference to some other
363 : * reallocated pointer. This is possible if the allocator
364 : * is using a freelist like SLAB_TYPESAFE_BY_RCU where the
365 : * fence remains valid for the RCU grace period, but it
366 : * may be reallocated. When using such allocators, we are
367 : * responsible for ensuring the reference we get is to
368 : * the right fence, as below.
369 : */
370 0 : if (fence == rcu_access_pointer(*fencep))
371 : return rcu_pointer_handoff(fence);
372 :
373 : dma_fence_put(fence);
374 : } while (1);
375 : }
376 :
377 : #ifdef CONFIG_LOCKDEP
378 : bool dma_fence_begin_signalling(void);
379 : void dma_fence_end_signalling(bool cookie);
380 : void __dma_fence_might_wait(void);
381 : #else
382 : static inline bool dma_fence_begin_signalling(void)
383 : {
384 : return true;
385 : }
386 : static inline void dma_fence_end_signalling(bool cookie) {}
387 : static inline void __dma_fence_might_wait(void) {}
388 : #endif
389 :
390 : int dma_fence_signal(struct dma_fence *fence);
391 : int dma_fence_signal_locked(struct dma_fence *fence);
392 : int dma_fence_signal_timestamp(struct dma_fence *fence, ktime_t timestamp);
393 : int dma_fence_signal_timestamp_locked(struct dma_fence *fence,
394 : ktime_t timestamp);
395 : signed long dma_fence_default_wait(struct dma_fence *fence,
396 : bool intr, signed long timeout);
397 : int dma_fence_add_callback(struct dma_fence *fence,
398 : struct dma_fence_cb *cb,
399 : dma_fence_func_t func);
400 : bool dma_fence_remove_callback(struct dma_fence *fence,
401 : struct dma_fence_cb *cb);
402 : void dma_fence_enable_sw_signaling(struct dma_fence *fence);
403 :
404 : /**
405 : * dma_fence_is_signaled_locked - Return an indication if the fence
406 : * is signaled yet.
407 : * @fence: the fence to check
408 : *
409 : * Returns true if the fence was already signaled, false if not. Since this
410 : * function doesn't enable signaling, it is not guaranteed to ever return
411 : * true if dma_fence_add_callback(), dma_fence_wait() or
412 : * dma_fence_enable_sw_signaling() haven't been called before.
413 : *
414 : * This function requires &dma_fence.lock to be held.
415 : *
416 : * See also dma_fence_is_signaled().
417 : */
418 : static inline bool
419 0 : dma_fence_is_signaled_locked(struct dma_fence *fence)
420 : {
421 0 : if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
422 : return true;
423 :
424 0 : if (fence->ops->signaled && fence->ops->signaled(fence)) {
425 0 : dma_fence_signal_locked(fence);
426 0 : return true;
427 : }
428 :
429 : return false;
430 : }
431 :
432 : /**
433 : * dma_fence_is_signaled - Return an indication if the fence is signaled yet.
434 : * @fence: the fence to check
435 : *
436 : * Returns true if the fence was already signaled, false if not. Since this
437 : * function doesn't enable signaling, it is not guaranteed to ever return
438 : * true if dma_fence_add_callback(), dma_fence_wait() or
439 : * dma_fence_enable_sw_signaling() haven't been called before.
440 : *
441 : * It's recommended for seqno fences to call dma_fence_signal when the
442 : * operation is complete, it makes it possible to prevent issues from
443 : * wraparound between time of issue and time of use by checking the return
444 : * value of this function before calling hardware-specific wait instructions.
445 : *
446 : * See also dma_fence_is_signaled_locked().
447 : */
448 : static inline bool
449 0 : dma_fence_is_signaled(struct dma_fence *fence)
450 : {
451 0 : if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
452 : return true;
453 :
454 0 : if (fence->ops->signaled && fence->ops->signaled(fence)) {
455 0 : dma_fence_signal(fence);
456 0 : return true;
457 : }
458 :
459 : return false;
460 : }
461 :
462 : /**
463 : * __dma_fence_is_later - return if f1 is chronologically later than f2
464 : * @f1: the first fence's seqno
465 : * @f2: the second fence's seqno from the same context
466 : * @ops: dma_fence_ops associated with the seqno
467 : *
468 : * Returns true if f1 is chronologically later than f2. Both fences must be
469 : * from the same context, since a seqno is not common across contexts.
470 : */
471 : static inline bool __dma_fence_is_later(u64 f1, u64 f2,
472 : const struct dma_fence_ops *ops)
473 : {
474 : /* This is for backward compatibility with drivers which can only handle
475 : * 32bit sequence numbers. Use a 64bit compare when the driver says to
476 : * do so.
477 : */
478 0 : if (ops->use_64bit_seqno)
479 0 : return f1 > f2;
480 :
481 0 : return (int)(lower_32_bits(f1) - lower_32_bits(f2)) > 0;
482 : }
483 :
484 : /**
485 : * dma_fence_is_later - return if f1 is chronologically later than f2
486 : * @f1: the first fence from the same context
487 : * @f2: the second fence from the same context
488 : *
489 : * Returns true if f1 is chronologically later than f2. Both fences must be
490 : * from the same context, since a seqno is not re-used across contexts.
491 : */
492 0 : static inline bool dma_fence_is_later(struct dma_fence *f1,
493 : struct dma_fence *f2)
494 : {
495 0 : if (WARN_ON(f1->context != f2->context))
496 : return false;
497 :
498 0 : return __dma_fence_is_later(f1->seqno, f2->seqno, f1->ops);
499 : }
500 :
501 : /**
502 : * dma_fence_later - return the chronologically later fence
503 : * @f1: the first fence from the same context
504 : * @f2: the second fence from the same context
505 : *
506 : * Returns NULL if both fences are signaled, otherwise the fence that would be
507 : * signaled last. Both fences must be from the same context, since a seqno is
508 : * not re-used across contexts.
509 : */
510 : static inline struct dma_fence *dma_fence_later(struct dma_fence *f1,
511 : struct dma_fence *f2)
512 : {
513 : if (WARN_ON(f1->context != f2->context))
514 : return NULL;
515 :
516 : /*
517 : * Can't check just DMA_FENCE_FLAG_SIGNALED_BIT here, it may never
518 : * have been set if enable_signaling wasn't called, and enabling that
519 : * here is overkill.
520 : */
521 : if (dma_fence_is_later(f1, f2))
522 : return dma_fence_is_signaled(f1) ? NULL : f1;
523 : else
524 : return dma_fence_is_signaled(f2) ? NULL : f2;
525 : }
526 :
527 : /**
528 : * dma_fence_get_status_locked - returns the status upon completion
529 : * @fence: the dma_fence to query
530 : *
531 : * Drivers can supply an optional error status condition before they signal
532 : * the fence (to indicate whether the fence was completed due to an error
533 : * rather than success). The value of the status condition is only valid
534 : * if the fence has been signaled, dma_fence_get_status_locked() first checks
535 : * the signal state before reporting the error status.
536 : *
537 : * Returns 0 if the fence has not yet been signaled, 1 if the fence has
538 : * been signaled without an error condition, or a negative error code
539 : * if the fence has been completed in err.
540 : */
541 : static inline int dma_fence_get_status_locked(struct dma_fence *fence)
542 : {
543 0 : if (dma_fence_is_signaled_locked(fence))
544 0 : return fence->error ?: 1;
545 : else
546 : return 0;
547 : }
548 :
549 : int dma_fence_get_status(struct dma_fence *fence);
550 :
551 : /**
552 : * dma_fence_set_error - flag an error condition on the fence
553 : * @fence: the dma_fence
554 : * @error: the error to store
555 : *
556 : * Drivers can supply an optional error status condition before they signal
557 : * the fence, to indicate that the fence was completed due to an error
558 : * rather than success. This must be set before signaling (so that the value
559 : * is visible before any waiters on the signal callback are woken). This
560 : * helper exists to help catching erroneous setting of #dma_fence.error.
561 : */
562 0 : static inline void dma_fence_set_error(struct dma_fence *fence,
563 : int error)
564 : {
565 0 : WARN_ON(test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags));
566 0 : WARN_ON(error >= 0 || error < -MAX_ERRNO);
567 :
568 0 : fence->error = error;
569 0 : }
570 :
571 : signed long dma_fence_wait_timeout(struct dma_fence *,
572 : bool intr, signed long timeout);
573 : signed long dma_fence_wait_any_timeout(struct dma_fence **fences,
574 : uint32_t count,
575 : bool intr, signed long timeout,
576 : uint32_t *idx);
577 :
578 : /**
579 : * dma_fence_wait - sleep until the fence gets signaled
580 : * @fence: the fence to wait on
581 : * @intr: if true, do an interruptible wait
582 : *
583 : * This function will return -ERESTARTSYS if interrupted by a signal,
584 : * or 0 if the fence was signaled. Other error values may be
585 : * returned on custom implementations.
586 : *
587 : * Performs a synchronous wait on this fence. It is assumed the caller
588 : * directly or indirectly holds a reference to the fence, otherwise the
589 : * fence might be freed before return, resulting in undefined behavior.
590 : *
591 : * See also dma_fence_wait_timeout() and dma_fence_wait_any_timeout().
592 : */
593 : static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
594 : {
595 : signed long ret;
596 :
597 : /* Since dma_fence_wait_timeout cannot timeout with
598 : * MAX_SCHEDULE_TIMEOUT, only valid return values are
599 : * -ERESTARTSYS and MAX_SCHEDULE_TIMEOUT.
600 : */
601 0 : ret = dma_fence_wait_timeout(fence, intr, MAX_SCHEDULE_TIMEOUT);
602 :
603 0 : return ret < 0 ? ret : 0;
604 : }
605 :
606 : void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline);
607 :
608 : struct dma_fence *dma_fence_get_stub(void);
609 : struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp);
610 : u64 dma_fence_context_alloc(unsigned num);
611 :
612 : extern const struct dma_fence_ops dma_fence_array_ops;
613 : extern const struct dma_fence_ops dma_fence_chain_ops;
614 :
615 : /**
616 : * dma_fence_is_array - check if a fence is from the array subclass
617 : * @fence: the fence to test
618 : *
619 : * Return true if it is a dma_fence_array and false otherwise.
620 : */
621 : static inline bool dma_fence_is_array(struct dma_fence *fence)
622 : {
623 : return fence->ops == &dma_fence_array_ops;
624 : }
625 :
626 : /**
627 : * dma_fence_is_chain - check if a fence is from the chain subclass
628 : * @fence: the fence to test
629 : *
630 : * Return true if it is a dma_fence_chain and false otherwise.
631 : */
632 : static inline bool dma_fence_is_chain(struct dma_fence *fence)
633 : {
634 0 : return fence->ops == &dma_fence_chain_ops;
635 : }
636 :
637 : /**
638 : * dma_fence_is_container - check if a fence is a container for other fences
639 : * @fence: the fence to test
640 : *
641 : * Return true if this fence is a container for other fences, false otherwise.
642 : * This is important since we can't build up large fence structure or otherwise
643 : * we run into recursion during operation on those fences.
644 : */
645 : static inline bool dma_fence_is_container(struct dma_fence *fence)
646 : {
647 0 : return dma_fence_is_array(fence) || dma_fence_is_chain(fence);
648 : }
649 :
650 : #endif /* __LINUX_DMA_FENCE_H */
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