1/*
  2 * Copyright © 2008-2015 Intel Corporation
  3 *
  4 * Permission is hereby granted, free of charge, to any person obtaining a
  5 * copy of this software and associated documentation files (the "Software"),
  6 * to deal in the Software without restriction, including without limitation
  7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  8 * and/or sell copies of the Software, and to permit persons to whom the
  9 * Software is furnished to do so, subject to the following conditions:
 10 *
 11 * The above copyright notice and this permission notice (including the next
 12 * paragraph) shall be included in all copies or substantial portions of the
 13 * Software.
 14 *
 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 21 * IN THE SOFTWARE.
 22 *
 23 */
 24
 25#ifndef I915_GEM_REQUEST_H
 26#define I915_GEM_REQUEST_H
 27
 28#include <linux/dma-fence.h>
 29
 30#include "i915_gem.h"
 31#include "i915_sw_fence.h"
 32
 33struct drm_file;
 34struct drm_i915_gem_object;
 35
 36struct intel_wait {
 37	struct rb_node node;
 38	struct task_struct *tsk;
 39	u32 seqno;
 40};
 41
 42struct intel_signal_node {
 43	struct rb_node node;
 44	struct intel_wait wait;
 45};
 46
 47struct i915_dependency {
 48	struct i915_priotree *signaler;
 49	struct list_head signal_link;
 50	struct list_head wait_link;
 51	struct list_head dfs_link;
 52	unsigned long flags;
 53#define I915_DEPENDENCY_ALLOC BIT(0)
 54};
 55
 56/* Requests exist in a complex web of interdependencies. Each request
 57 * has to wait for some other request to complete before it is ready to be run
 58 * (e.g. we have to wait until the pixels have been rendering into a texture
 59 * before we can copy from it). We track the readiness of a request in terms
 60 * of fences, but we also need to keep the dependency tree for the lifetime
 61 * of the request (beyond the life of an individual fence). We use the tree
 62 * at various points to reorder the requests whilst keeping the requests
 63 * in order with respect to their various dependencies.
 64 */
 65struct i915_priotree {
 66	struct list_head signalers_list; /* those before us, we depend upon */
 67	struct list_head waiters_list; /* those after us, they depend upon us */
 68	struct rb_node node;
 69	int priority;
 70#define I915_PRIORITY_MAX 1024
 71#define I915_PRIORITY_MIN (-I915_PRIORITY_MAX)
 72};
 73
 74/**
 75 * Request queue structure.
 76 *
 77 * The request queue allows us to note sequence numbers that have been emitted
 78 * and may be associated with active buffers to be retired.
 79 *
 80 * By keeping this list, we can avoid having to do questionable sequence
 81 * number comparisons on buffer last_read|write_seqno. It also allows an
 82 * emission time to be associated with the request for tracking how far ahead
 83 * of the GPU the submission is.
 84 *
 85 * When modifying this structure be very aware that we perform a lockless
 86 * RCU lookup of it that may race against reallocation of the struct
 87 * from the slab freelist. We intentionally do not zero the structure on
 88 * allocation so that the lookup can use the dangling pointers (and is
 89 * cogniscent that those pointers may be wrong). Instead, everything that
 90 * needs to be initialised must be done so explicitly.
 91 *
 92 * The requests are reference counted.
 93 */
 94struct drm_i915_gem_request {
 95	struct dma_fence fence;
 96	spinlock_t lock;
 97
 98	/** On Which ring this request was generated */
 99	struct drm_i915_private *i915;
100
101	/**
102	 * Context and ring buffer related to this request
103	 * Contexts are refcounted, so when this request is associated with a
104	 * context, we must increment the context's refcount, to guarantee that
105	 * it persists while any request is linked to it. Requests themselves
106	 * are also refcounted, so the request will only be freed when the last
107	 * reference to it is dismissed, and the code in
108	 * i915_gem_request_free() will then decrement the refcount on the
109	 * context.
110	 */
111	struct i915_gem_context *ctx;
112	struct intel_engine_cs *engine;
113	struct intel_ring *ring;
114	struct intel_timeline *timeline;
115	struct intel_signal_node signaling;
116
117	/* Fences for the various phases in the request's lifetime.
118	 *
119	 * The submit fence is used to await upon all of the request's
120	 * dependencies. When it is signaled, the request is ready to run.
121	 * It is used by the driver to then queue the request for execution.
122	 *
123	 * The execute fence is used to signal when the request has been
124	 * sent to hardware.
125	 *
126	 * It is illegal for the submit fence of one request to wait upon the
127	 * execute fence of an earlier request. It should be sufficient to
128	 * wait upon the submit fence of the earlier request.
129	 */
130	struct i915_sw_fence submit;
131	struct i915_sw_fence execute;
132	wait_queue_t submitq;
133	wait_queue_t execq;
134
135	/* A list of everyone we wait upon, and everyone who waits upon us.
136	 * Even though we will not be submitted to the hardware before the
137	 * submit fence is signaled (it waits for all external events as well
138	 * as our own requests), the scheduler still needs to know the
139	 * dependency tree for the lifetime of the request (from execbuf
140	 * to retirement), i.e. bidirectional dependency information for the
141	 * request not tied to individual fences.
142	 */
143	struct i915_priotree priotree;
144	struct i915_dependency dep;
145
146	u32 global_seqno;
147
148	/** GEM sequence number associated with the previous request,
149	 * when the HWS breadcrumb is equal to this the GPU is processing
150	 * this request.
151	 */
152	u32 previous_seqno;
153
154	/** Position in the ring of the start of the request */
155	u32 head;
156
157	/**
158	 * Position in the ring of the start of the postfix.
159	 * This is required to calculate the maximum available ring space
160	 * without overwriting the postfix.
161	 */
162	u32 postfix;
163
164	/** Position in the ring of the end of the whole request */
165	u32 tail;
166
167	/** Position in the ring of the end of any workarounds after the tail */
168	u32 wa_tail;
169
170	/** Preallocate space in the ring for the emitting the request */
171	u32 reserved_space;
172
173	/**
174	 * Context related to the previous request.
175	 * As the contexts are accessed by the hardware until the switch is
176	 * completed to a new context, the hardware may still be writing
177	 * to the context object after the breadcrumb is visible. We must
178	 * not unpin/unbind/prune that object whilst still active and so
179	 * we keep the previous context pinned until the following (this)
180	 * request is retired.
181	 */
182	struct i915_gem_context *previous_context;
183
184	/** Batch buffer related to this request if any (used for
185	 * error state dump only).
186	 */
187	struct i915_vma *batch;
188	struct list_head active_list;
189
190	/** Time at which this request was emitted, in jiffies. */
191	unsigned long emitted_jiffies;
192
193	/** engine->request_list entry for this request */
194	struct list_head link;
195
196	/** ring->request_list entry for this request */
197	struct list_head ring_link;
198
199	struct drm_i915_file_private *file_priv;
200	/** file_priv list entry for this request */
201	struct list_head client_list;
202};
203
204extern const struct dma_fence_ops i915_fence_ops;
205
206static inline bool dma_fence_is_i915(const struct dma_fence *fence)
207{
208	return fence->ops == &i915_fence_ops;
209}
210
211struct drm_i915_gem_request * __must_check
212i915_gem_request_alloc(struct intel_engine_cs *engine,
213		       struct i915_gem_context *ctx);
214int i915_gem_request_add_to_client(struct drm_i915_gem_request *req,
215				   struct drm_file *file);
216void i915_gem_request_retire_upto(struct drm_i915_gem_request *req);
217
218static inline struct drm_i915_gem_request *
219to_request(struct dma_fence *fence)
220{
221	/* We assume that NULL fence/request are interoperable */
222	BUILD_BUG_ON(offsetof(struct drm_i915_gem_request, fence) != 0);
223	GEM_BUG_ON(fence && !dma_fence_is_i915(fence));
224	return container_of(fence, struct drm_i915_gem_request, fence);
225}
226
227static inline struct drm_i915_gem_request *
228i915_gem_request_get(struct drm_i915_gem_request *req)
229{
230	return to_request(dma_fence_get(&req->fence));
231}
232
233static inline struct drm_i915_gem_request *
234i915_gem_request_get_rcu(struct drm_i915_gem_request *req)
235{
236	return to_request(dma_fence_get_rcu(&req->fence));
237}
238
239static inline void
240i915_gem_request_put(struct drm_i915_gem_request *req)
241{
242	dma_fence_put(&req->fence);
243}
244
245static inline void i915_gem_request_assign(struct drm_i915_gem_request **pdst,
246					   struct drm_i915_gem_request *src)
247{
248	if (src)
249		i915_gem_request_get(src);
250
251	if (*pdst)
252		i915_gem_request_put(*pdst);
253
254	*pdst = src;
255}
256
257int
258i915_gem_request_await_object(struct drm_i915_gem_request *to,
259			      struct drm_i915_gem_object *obj,
260			      bool write);
261int i915_gem_request_await_dma_fence(struct drm_i915_gem_request *req,
262				     struct dma_fence *fence);
263
264void __i915_add_request(struct drm_i915_gem_request *req, bool flush_caches);
265#define i915_add_request(req) \
266	__i915_add_request(req, true)
267#define i915_add_request_no_flush(req) \
268	__i915_add_request(req, false)
269
270void __i915_gem_request_submit(struct drm_i915_gem_request *request);
271void i915_gem_request_submit(struct drm_i915_gem_request *request);
272
273struct intel_rps_client;
274#define NO_WAITBOOST ERR_PTR(-1)
275#define IS_RPS_CLIENT(p) (!IS_ERR(p))
276#define IS_RPS_USER(p) (!IS_ERR_OR_NULL(p))
277
278long i915_wait_request(struct drm_i915_gem_request *req,
279		       unsigned int flags,
280		       long timeout)
281	__attribute__((nonnull(1)));
282#define I915_WAIT_INTERRUPTIBLE	BIT(0)
283#define I915_WAIT_LOCKED	BIT(1) /* struct_mutex held, handle GPU reset */
284#define I915_WAIT_ALL		BIT(2) /* used by i915_gem_object_wait() */
285
286static inline u32 intel_engine_get_seqno(struct intel_engine_cs *engine);
287
288/**
289 * Returns true if seq1 is later than seq2.
290 */
291static inline bool i915_seqno_passed(u32 seq1, u32 seq2)
292{
293	return (s32)(seq1 - seq2) >= 0;
294}
295
296static inline bool
297__i915_gem_request_started(const struct drm_i915_gem_request *req)
298{
299	GEM_BUG_ON(!req->global_seqno);
300	return i915_seqno_passed(intel_engine_get_seqno(req->engine),
301				 req->previous_seqno);
302}
303
304static inline bool
305i915_gem_request_started(const struct drm_i915_gem_request *req)
306{
307	if (!req->global_seqno)
308		return false;
309
310	return __i915_gem_request_started(req);
311}
312
313static inline bool
314__i915_gem_request_completed(const struct drm_i915_gem_request *req)
315{
316	GEM_BUG_ON(!req->global_seqno);
317	return i915_seqno_passed(intel_engine_get_seqno(req->engine),
318				 req->global_seqno);
319}
320
321static inline bool
322i915_gem_request_completed(const struct drm_i915_gem_request *req)
323{
324	if (!req->global_seqno)
325		return false;
326
327	return __i915_gem_request_completed(req);
328}
329
330bool __i915_spin_request(const struct drm_i915_gem_request *request,
331			 int state, unsigned long timeout_us);
332static inline bool i915_spin_request(const struct drm_i915_gem_request *request,
333				     int state, unsigned long timeout_us)
334{
335	return (__i915_gem_request_started(request) &&
336		__i915_spin_request(request, state, timeout_us));
337}
338
339/* We treat requests as fences. This is not be to confused with our
340 * "fence registers" but pipeline synchronisation objects ala GL_ARB_sync.
341 * We use the fences to synchronize access from the CPU with activity on the
342 * GPU, for example, we should not rewrite an object's PTE whilst the GPU
343 * is reading them. We also track fences at a higher level to provide
344 * implicit synchronisation around GEM objects, e.g. set-domain will wait
345 * for outstanding GPU rendering before marking the object ready for CPU
346 * access, or a pageflip will wait until the GPU is complete before showing
347 * the frame on the scanout.
348 *
349 * In order to use a fence, the object must track the fence it needs to
350 * serialise with. For example, GEM objects want to track both read and
351 * write access so that we can perform concurrent read operations between
352 * the CPU and GPU engines, as well as waiting for all rendering to
353 * complete, or waiting for the last GPU user of a "fence register". The
354 * object then embeds a #i915_gem_active to track the most recent (in
355 * retirement order) request relevant for the desired mode of access.
356 * The #i915_gem_active is updated with i915_gem_active_set() to track the
357 * most recent fence request, typically this is done as part of
358 * i915_vma_move_to_active().
359 *
360 * When the #i915_gem_active completes (is retired), it will
361 * signal its completion to the owner through a callback as well as mark
362 * itself as idle (i915_gem_active.request == NULL). The owner
363 * can then perform any action, such as delayed freeing of an active
364 * resource including itself.
365 */
366struct i915_gem_active;
367
368typedef void (*i915_gem_retire_fn)(struct i915_gem_active *,
369				   struct drm_i915_gem_request *);
370
371struct i915_gem_active {
372	struct drm_i915_gem_request __rcu *request;
373	struct list_head link;
374	i915_gem_retire_fn retire;
375};
376
377void i915_gem_retire_noop(struct i915_gem_active *,
378			  struct drm_i915_gem_request *request);
379
380/**
381 * init_request_active - prepares the activity tracker for use
382 * @active - the active tracker
383 * @func - a callback when then the tracker is retired (becomes idle),
384 *         can be NULL
385 *
386 * init_request_active() prepares the embedded @active struct for use as
387 * an activity tracker, that is for tracking the last known active request
388 * associated with it. When the last request becomes idle, when it is retired
389 * after completion, the optional callback @func is invoked.
390 */
391static inline void
392init_request_active(struct i915_gem_active *active,
393		    i915_gem_retire_fn retire)
394{
395	INIT_LIST_HEAD(&active->link);
396	active->retire = retire ?: i915_gem_retire_noop;
397}
398
399/**
400 * i915_gem_active_set - updates the tracker to watch the current request
401 * @active - the active tracker
402 * @request - the request to watch
403 *
404 * i915_gem_active_set() watches the given @request for completion. Whilst
405 * that @request is busy, the @active reports busy. When that @request is
406 * retired, the @active tracker is updated to report idle.
407 */
408static inline void
409i915_gem_active_set(struct i915_gem_active *active,
410		    struct drm_i915_gem_request *request)
411{
412	list_move(&active->link, &request->active_list);
413	rcu_assign_pointer(active->request, request);
414}
415
416/**
417 * i915_gem_active_set_retire_fn - updates the retirement callback
418 * @active - the active tracker
419 * @fn - the routine called when the request is retired
420 * @mutex - struct_mutex used to guard retirements
421 *
422 * i915_gem_active_set_retire_fn() updates the function pointer that
423 * is called when the final request associated with the @active tracker
424 * is retired.
425 */
426static inline void
427i915_gem_active_set_retire_fn(struct i915_gem_active *active,
428			      i915_gem_retire_fn fn,
429			      struct mutex *mutex)
430{
431	lockdep_assert_held(mutex);
432	active->retire = fn ?: i915_gem_retire_noop;
433}
434
435static inline struct drm_i915_gem_request *
436__i915_gem_active_peek(const struct i915_gem_active *active)
437{
438	/* Inside the error capture (running with the driver in an unknown
439	 * state), we want to bend the rules slightly (a lot).
440	 *
441	 * Work is in progress to make it safer, in the meantime this keeps
442	 * the known issue from spamming the logs.
443	 */
444	return rcu_dereference_protected(active->request, 1);
445}
446
447/**
448 * i915_gem_active_raw - return the active request
449 * @active - the active tracker
450 *
451 * i915_gem_active_raw() returns the current request being tracked, or NULL.
452 * It does not obtain a reference on the request for the caller, so the caller
453 * must hold struct_mutex.
454 */
455static inline struct drm_i915_gem_request *
456i915_gem_active_raw(const struct i915_gem_active *active, struct mutex *mutex)
457{
458	return rcu_dereference_protected(active->request,
459					 lockdep_is_held(mutex));
460}
461
462/**
463 * i915_gem_active_peek - report the active request being monitored
464 * @active - the active tracker
465 *
466 * i915_gem_active_peek() returns the current request being tracked if
467 * still active, or NULL. It does not obtain a reference on the request
468 * for the caller, so the caller must hold struct_mutex.
469 */
470static inline struct drm_i915_gem_request *
471i915_gem_active_peek(const struct i915_gem_active *active, struct mutex *mutex)
472{
473	struct drm_i915_gem_request *request;
474
475	request = i915_gem_active_raw(active, mutex);
476	if (!request || i915_gem_request_completed(request))
477		return NULL;
478
479	return request;
480}
481
482/**
483 * i915_gem_active_get - return a reference to the active request
484 * @active - the active tracker
485 *
486 * i915_gem_active_get() returns a reference to the active request, or NULL
487 * if the active tracker is idle. The caller must hold struct_mutex.
488 */
489static inline struct drm_i915_gem_request *
490i915_gem_active_get(const struct i915_gem_active *active, struct mutex *mutex)
491{
492	return i915_gem_request_get(i915_gem_active_peek(active, mutex));
493}
494
495/**
496 * __i915_gem_active_get_rcu - return a reference to the active request
497 * @active - the active tracker
498 *
499 * __i915_gem_active_get() returns a reference to the active request, or NULL
500 * if the active tracker is idle. The caller must hold the RCU read lock, but
501 * the returned pointer is safe to use outside of RCU.
502 */
503static inline struct drm_i915_gem_request *
504__i915_gem_active_get_rcu(const struct i915_gem_active *active)
505{
506	/* Performing a lockless retrieval of the active request is super
507	 * tricky. SLAB_DESTROY_BY_RCU merely guarantees that the backing
508	 * slab of request objects will not be freed whilst we hold the
509	 * RCU read lock. It does not guarantee that the request itself
510	 * will not be freed and then *reused*. Viz,
511	 *
512	 * Thread A			Thread B
513	 *
514	 * req = active.request
515	 *				retire(req) -> free(req);
516	 *				(req is now first on the slab freelist)
517	 *				active.request = NULL
518	 *
519	 *				req = new submission on a new object
520	 * ref(req)
521	 *
522	 * To prevent the request from being reused whilst the caller
523	 * uses it, we take a reference like normal. Whilst acquiring
524	 * the reference we check that it is not in a destroyed state
525	 * (refcnt == 0). That prevents the request being reallocated
526	 * whilst the caller holds on to it. To check that the request
527	 * was not reallocated as we acquired the reference we have to
528	 * check that our request remains the active request across
529	 * the lookup, in the same manner as a seqlock. The visibility
530	 * of the pointer versus the reference counting is controlled
531	 * by using RCU barriers (rcu_dereference and rcu_assign_pointer).
532	 *
533	 * In the middle of all that, we inspect whether the request is
534	 * complete. Retiring is lazy so the request may be completed long
535	 * before the active tracker is updated. Querying whether the
536	 * request is complete is far cheaper (as it involves no locked
537	 * instructions setting cachelines to exclusive) than acquiring
538	 * the reference, so we do it first. The RCU read lock ensures the
539	 * pointer dereference is valid, but does not ensure that the
540	 * seqno nor HWS is the right one! However, if the request was
541	 * reallocated, that means the active tracker's request was complete.
542	 * If the new request is also complete, then both are and we can
543	 * just report the active tracker is idle. If the new request is
544	 * incomplete, then we acquire a reference on it and check that
545	 * it remained the active request.
546	 *
547	 * It is then imperative that we do not zero the request on
548	 * reallocation, so that we can chase the dangling pointers!
549	 * See i915_gem_request_alloc().
550	 */
551	do {
552		struct drm_i915_gem_request *request;
553
554		request = rcu_dereference(active->request);
555		if (!request || i915_gem_request_completed(request))
556			return NULL;
557
558		/* An especially silly compiler could decide to recompute the
559		 * result of i915_gem_request_completed, more specifically
560		 * re-emit the load for request->fence.seqno. A race would catch
561		 * a later seqno value, which could flip the result from true to
562		 * false. Which means part of the instructions below might not
563		 * be executed, while later on instructions are executed. Due to
564		 * barriers within the refcounting the inconsistency can't reach
565		 * past the call to i915_gem_request_get_rcu, but not executing
566		 * that while still executing i915_gem_request_put() creates
567		 * havoc enough.  Prevent this with a compiler barrier.
568		 */
569		barrier();
570
571		request = i915_gem_request_get_rcu(request);
572
573		/* What stops the following rcu_access_pointer() from occurring
574		 * before the above i915_gem_request_get_rcu()? If we were
575		 * to read the value before pausing to get the reference to
576		 * the request, we may not notice a change in the active
577		 * tracker.
578		 *
579		 * The rcu_access_pointer() is a mere compiler barrier, which
580		 * means both the CPU and compiler are free to perform the
581		 * memory read without constraint. The compiler only has to
582		 * ensure that any operations after the rcu_access_pointer()
583		 * occur afterwards in program order. This means the read may
584		 * be performed earlier by an out-of-order CPU, or adventurous
585		 * compiler.
586		 *
587		 * The atomic operation at the heart of
588		 * i915_gem_request_get_rcu(), see dma_fence_get_rcu(), is
589		 * atomic_inc_not_zero() which is only a full memory barrier
590		 * when successful. That is, if i915_gem_request_get_rcu()
591		 * returns the request (and so with the reference counted
592		 * incremented) then the following read for rcu_access_pointer()
593		 * must occur after the atomic operation and so confirm
594		 * that this request is the one currently being tracked.
595		 *
596		 * The corresponding write barrier is part of
597		 * rcu_assign_pointer().
598		 */
599		if (!request || request == rcu_access_pointer(active->request))
600			return rcu_pointer_handoff(request);
601
602		i915_gem_request_put(request);
603	} while (1);
604}
605
606/**
607 * i915_gem_active_get_unlocked - return a reference to the active request
608 * @active - the active tracker
609 *
610 * i915_gem_active_get_unlocked() returns a reference to the active request,
611 * or NULL if the active tracker is idle. The reference is obtained under RCU,
612 * so no locking is required by the caller.
613 *
614 * The reference should be freed with i915_gem_request_put().
615 */
616static inline struct drm_i915_gem_request *
617i915_gem_active_get_unlocked(const struct i915_gem_active *active)
618{
619	struct drm_i915_gem_request *request;
620
621	rcu_read_lock();
622	request = __i915_gem_active_get_rcu(active);
623	rcu_read_unlock();
624
625	return request;
626}
627
628/**
629 * i915_gem_active_isset - report whether the active tracker is assigned
630 * @active - the active tracker
631 *
632 * i915_gem_active_isset() returns true if the active tracker is currently
633 * assigned to a request. Due to the lazy retiring, that request may be idle
634 * and this may report stale information.
635 */
636static inline bool
637i915_gem_active_isset(const struct i915_gem_active *active)
638{
639	return rcu_access_pointer(active->request);
640}
641
642/**
643 * i915_gem_active_wait - waits until the request is completed
644 * @active - the active request on which to wait
645 * @flags - how to wait
646 * @timeout - how long to wait at most
647 * @rps - userspace client to charge for a waitboost
648 *
649 * i915_gem_active_wait() waits until the request is completed before
650 * returning, without requiring any locks to be held. Note that it does not
651 * retire any requests before returning.
652 *
653 * This function relies on RCU in order to acquire the reference to the active
654 * request without holding any locks. See __i915_gem_active_get_rcu() for the
655 * glory details on how that is managed. Once the reference is acquired, we
656 * can then wait upon the request, and afterwards release our reference,
657 * free of any locking.
658 *
659 * This function wraps i915_wait_request(), see it for the full details on
660 * the arguments.
661 *
662 * Returns 0 if successful, or a negative error code.
663 */
664static inline int
665i915_gem_active_wait(const struct i915_gem_active *active, unsigned int flags)
666{
667	struct drm_i915_gem_request *request;
668	long ret = 0;
669
670	request = i915_gem_active_get_unlocked(active);
671	if (request) {
672		ret = i915_wait_request(request, flags, MAX_SCHEDULE_TIMEOUT);
673		i915_gem_request_put(request);
674	}
675
676	return ret < 0 ? ret : 0;
677}
678
679/**
680 * i915_gem_active_retire - waits until the request is retired
681 * @active - the active request on which to wait
682 *
683 * i915_gem_active_retire() waits until the request is completed,
684 * and then ensures that at least the retirement handler for this
685 * @active tracker is called before returning. If the @active
686 * tracker is idle, the function returns immediately.
687 */
688static inline int __must_check
689i915_gem_active_retire(struct i915_gem_active *active,
690		       struct mutex *mutex)
691{
692	struct drm_i915_gem_request *request;
693	long ret;
694
695	request = i915_gem_active_raw(active, mutex);
696	if (!request)
697		return 0;
698
699	ret = i915_wait_request(request,
700				I915_WAIT_INTERRUPTIBLE | I915_WAIT_LOCKED,
701				MAX_SCHEDULE_TIMEOUT);
702	if (ret < 0)
703		return ret;
704
705	list_del_init(&active->link);
706	RCU_INIT_POINTER(active->request, NULL);
707
708	active->retire(active, request);
709
710	return 0;
711}
712
713#define for_each_active(mask, idx) \
714	for (; mask ? idx = ffs(mask) - 1, 1 : 0; mask &= ~BIT(idx))
715
716#endif /* I915_GEM_REQUEST_H */