xref: /linux/drivers/gpu/drm/i915/i915_sw_fence.c (revision dd093fb0) 
1 /*
2  * SPDX-License-Identifier: MIT
3  *
4  * (C) Copyright 2016 Intel Corporation
5  */
6 
7 #include <linux/slab.h>
8 #include <linux/dma-fence.h>
9 #include <linux/irq_work.h>
10 #include <linux/dma-resv.h>
11 
12 #include "i915_sw_fence.h"
13 #include "i915_selftest.h"
14 
15 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
16 #define I915_SW_FENCE_BUG_ON(expr) BUG_ON(expr)
17 #else
18 #define I915_SW_FENCE_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
19 #endif
20 
21 #ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
22 static DEFINE_SPINLOCK(i915_sw_fence_lock);
23 #endif
24 
25 #define WQ_FLAG_BITS \
26 	BITS_PER_TYPE(typeof_member(struct wait_queue_entry, flags))
27 
28 /* after WQ_FLAG_* for safety */
29 #define I915_SW_FENCE_FLAG_FENCE BIT(WQ_FLAG_BITS - 1)
30 #define I915_SW_FENCE_FLAG_ALLOC BIT(WQ_FLAG_BITS - 2)
31 
32 enum {
33 	DEBUG_FENCE_IDLE = 0,
34 	DEBUG_FENCE_NOTIFY,
35 };
36 
37 static void *i915_sw_fence_debug_hint(void *addr)
38 {
39 	return (void *)(((struct i915_sw_fence *)addr)->fn);
40 }
41 
42 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
43 
44 static const struct debug_obj_descr i915_sw_fence_debug_descr = {
45 	.name = "i915_sw_fence",
46 	.debug_hint = i915_sw_fence_debug_hint,
47 };
48 
49 static inline void debug_fence_init(struct i915_sw_fence *fence)
50 {
51 	debug_object_init(fence, &i915_sw_fence_debug_descr);
52 }
53 
54 static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
55 {
56 	debug_object_init_on_stack(fence, &i915_sw_fence_debug_descr);
57 }
58 
59 static inline void debug_fence_activate(struct i915_sw_fence *fence)
60 {
61 	debug_object_activate(fence, &i915_sw_fence_debug_descr);
62 }
63 
64 static inline void debug_fence_set_state(struct i915_sw_fence *fence,
65 					 int old, int new)
66 {
67 	debug_object_active_state(fence, &i915_sw_fence_debug_descr, old, new);
68 }
69 
70 static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
71 {
72 	debug_object_deactivate(fence, &i915_sw_fence_debug_descr);
73 }
74 
75 static inline void debug_fence_destroy(struct i915_sw_fence *fence)
76 {
77 	debug_object_destroy(fence, &i915_sw_fence_debug_descr);
78 }
79 
80 static inline void debug_fence_free(struct i915_sw_fence *fence)
81 {
82 	debug_object_free(fence, &i915_sw_fence_debug_descr);
83 	smp_wmb(); /* flush the change in state before reallocation */
84 }
85 
86 static inline void debug_fence_assert(struct i915_sw_fence *fence)
87 {
88 	debug_object_assert_init(fence, &i915_sw_fence_debug_descr);
89 }
90 
91 #else
92 
93 static inline void debug_fence_init(struct i915_sw_fence *fence)
94 {
95 }
96 
97 static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
98 {
99 }
100 
101 static inline void debug_fence_activate(struct i915_sw_fence *fence)
102 {
103 }
104 
105 static inline void debug_fence_set_state(struct i915_sw_fence *fence,
106 					 int old, int new)
107 {
108 }
109 
110 static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
111 {
112 }
113 
114 static inline void debug_fence_destroy(struct i915_sw_fence *fence)
115 {
116 }
117 
118 static inline void debug_fence_free(struct i915_sw_fence *fence)
119 {
120 }
121 
122 static inline void debug_fence_assert(struct i915_sw_fence *fence)
123 {
124 }
125 
126 #endif
127 
128 static int __i915_sw_fence_notify(struct i915_sw_fence *fence,
129 				  enum i915_sw_fence_notify state)
130 {
131 	return fence->fn(fence, state);
132 }
133 
134 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
135 void i915_sw_fence_fini(struct i915_sw_fence *fence)
136 {
137 	debug_fence_free(fence);
138 }
139 #endif
140 
141 static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
142 					struct list_head *continuation)
143 {
144 	wait_queue_head_t *x = &fence->wait;
145 	wait_queue_entry_t *pos, *next;
146 	unsigned long flags;
147 
148 	debug_fence_deactivate(fence);
149 	atomic_set_release(&fence->pending, -1); /* 0 -> -1 [done] */
150 
151 	/*
152 	 * To prevent unbounded recursion as we traverse the graph of
153 	 * i915_sw_fences, we move the entry list from this, the next ready
154 	 * fence, to the tail of the original fence's entry list
155 	 * (and so added to the list to be woken).
156 	 */
157 
158 	spin_lock_irqsave_nested(&x->lock, flags, 1 + !!continuation);
159 	if (continuation) {
160 		list_for_each_entry_safe(pos, next, &x->head, entry) {
161 			if (pos->flags & I915_SW_FENCE_FLAG_FENCE)
162 				list_move_tail(&pos->entry, continuation);
163 			else
164 				pos->func(pos, TASK_NORMAL, 0, continuation);
165 		}
166 	} else {
167 		LIST_HEAD(extra);
168 
169 		do {
170 			list_for_each_entry_safe(pos, next, &x->head, entry) {
171 				int wake_flags;
172 
173 				wake_flags = 0;
174 				if (pos->flags & I915_SW_FENCE_FLAG_FENCE)
175 					wake_flags = fence->error;
176 
177 				pos->func(pos, TASK_NORMAL, wake_flags, &extra);
178 			}
179 
180 			if (list_empty(&extra))
181 				break;
182 
183 			list_splice_tail_init(&extra, &x->head);
184 		} while (1);
185 	}
186 	spin_unlock_irqrestore(&x->lock, flags);
187 
188 	debug_fence_assert(fence);
189 }
190 
191 static void __i915_sw_fence_complete(struct i915_sw_fence *fence,
192 				     struct list_head *continuation)
193 {
194 	debug_fence_assert(fence);
195 
196 	if (!atomic_dec_and_test(&fence->pending))
197 		return;
198 
199 	debug_fence_set_state(fence, DEBUG_FENCE_IDLE, DEBUG_FENCE_NOTIFY);
200 
201 	if (__i915_sw_fence_notify(fence, FENCE_COMPLETE) != NOTIFY_DONE)
202 		return;
203 
204 	debug_fence_set_state(fence, DEBUG_FENCE_NOTIFY, DEBUG_FENCE_IDLE);
205 
206 	__i915_sw_fence_wake_up_all(fence, continuation);
207 
208 	debug_fence_destroy(fence);
209 	__i915_sw_fence_notify(fence, FENCE_FREE);
210 }
211 
212 void i915_sw_fence_complete(struct i915_sw_fence *fence)
213 {
214 	debug_fence_assert(fence);
215 
216 	if (WARN_ON(i915_sw_fence_done(fence)))
217 		return;
218 
219 	__i915_sw_fence_complete(fence, NULL);
220 }
221 
222 bool i915_sw_fence_await(struct i915_sw_fence *fence)
223 {
224 	int pending;
225 
226 	/*
227 	 * It is only safe to add a new await to the fence while it has
228 	 * not yet been signaled (i.e. there are still existing signalers).
229 	 */
230 	pending = atomic_read(&fence->pending);
231 	do {
232 		if (pending < 1)
233 			return false;
234 	} while (!atomic_try_cmpxchg(&fence->pending, &pending, pending + 1));
235 
236 	return true;
237 }
238 
239 void __i915_sw_fence_init(struct i915_sw_fence *fence,
240 			  i915_sw_fence_notify_t fn,
241 			  const char *name,
242 			  struct lock_class_key *key)
243 {
244 	__init_waitqueue_head(&fence->wait, name, key);
245 	fence->fn = fn;
246 #ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
247 	fence->flags = 0;
248 #endif
249 
250 	i915_sw_fence_reinit(fence);
251 }
252 
253 void i915_sw_fence_reinit(struct i915_sw_fence *fence)
254 {
255 	debug_fence_init(fence);
256 
257 	atomic_set(&fence->pending, 1);
258 	fence->error = 0;
259 
260 	I915_SW_FENCE_BUG_ON(!list_empty(&fence->wait.head));
261 }
262 
263 void i915_sw_fence_commit(struct i915_sw_fence *fence)
264 {
265 	debug_fence_activate(fence);
266 	i915_sw_fence_complete(fence);
267 }
268 
269 static int i915_sw_fence_wake(wait_queue_entry_t *wq, unsigned mode, int flags, void *key)
270 {
271 	i915_sw_fence_set_error_once(wq->private, flags);
272 
273 	list_del(&wq->entry);
274 	__i915_sw_fence_complete(wq->private, key);
275 
276 	if (wq->flags & I915_SW_FENCE_FLAG_ALLOC)
277 		kfree(wq);
278 	return 0;
279 }
280 
281 #ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
282 static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
283 				    const struct i915_sw_fence * const signaler)
284 {
285 	wait_queue_entry_t *wq;
286 
287 	if (__test_and_set_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
288 		return false;
289 
290 	if (fence == signaler)
291 		return true;
292 
293 	list_for_each_entry(wq, &fence->wait.head, entry) {
294 		if (wq->func != i915_sw_fence_wake)
295 			continue;
296 
297 		if (__i915_sw_fence_check_if_after(wq->private, signaler))
298 			return true;
299 	}
300 
301 	return false;
302 }
303 
304 static void __i915_sw_fence_clear_checked_bit(struct i915_sw_fence *fence)
305 {
306 	wait_queue_entry_t *wq;
307 
308 	if (!__test_and_clear_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
309 		return;
310 
311 	list_for_each_entry(wq, &fence->wait.head, entry) {
312 		if (wq->func != i915_sw_fence_wake)
313 			continue;
314 
315 		__i915_sw_fence_clear_checked_bit(wq->private);
316 	}
317 }
318 
319 static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
320 				  const struct i915_sw_fence * const signaler)
321 {
322 	unsigned long flags;
323 	bool err;
324 
325 	spin_lock_irqsave(&i915_sw_fence_lock, flags);
326 	err = __i915_sw_fence_check_if_after(fence, signaler);
327 	__i915_sw_fence_clear_checked_bit(fence);
328 	spin_unlock_irqrestore(&i915_sw_fence_lock, flags);
329 
330 	return err;
331 }
332 #else
333 static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
334 					 const struct i915_sw_fence * const signaler)
335 {
336 	return false;
337 }
338 #endif
339 
340 static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
341 					  struct i915_sw_fence *signaler,
342 					  wait_queue_entry_t *wq, gfp_t gfp)
343 {
344 	unsigned int pending;
345 	unsigned long flags;
346 
347 	debug_fence_assert(fence);
348 	might_sleep_if(gfpflags_allow_blocking(gfp));
349 
350 	if (i915_sw_fence_done(signaler)) {
351 		i915_sw_fence_set_error_once(fence, signaler->error);
352 		return 0;
353 	}
354 
355 	debug_fence_assert(signaler);
356 
357 	/* The dependency graph must be acyclic. */
358 	if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
359 		return -EINVAL;
360 
361 	pending = I915_SW_FENCE_FLAG_FENCE;
362 	if (!wq) {
363 		wq = kmalloc(sizeof(*wq), gfp);
364 		if (!wq) {
365 			if (!gfpflags_allow_blocking(gfp))
366 				return -ENOMEM;
367 
368 			i915_sw_fence_wait(signaler);
369 			i915_sw_fence_set_error_once(fence, signaler->error);
370 			return 0;
371 		}
372 
373 		pending |= I915_SW_FENCE_FLAG_ALLOC;
374 	}
375 
376 	INIT_LIST_HEAD(&wq->entry);
377 	wq->flags = pending;
378 	wq->func = i915_sw_fence_wake;
379 	wq->private = fence;
380 
381 	i915_sw_fence_await(fence);
382 
383 	spin_lock_irqsave(&signaler->wait.lock, flags);
384 	if (likely(!i915_sw_fence_done(signaler))) {
385 		__add_wait_queue_entry_tail(&signaler->wait, wq);
386 		pending = 1;
387 	} else {
388 		i915_sw_fence_wake(wq, 0, signaler->error, NULL);
389 		pending = 0;
390 	}
391 	spin_unlock_irqrestore(&signaler->wait.lock, flags);
392 
393 	return pending;
394 }
395 
396 int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
397 				 struct i915_sw_fence *signaler,
398 				 wait_queue_entry_t *wq)
399 {
400 	return __i915_sw_fence_await_sw_fence(fence, signaler, wq, 0);
401 }
402 
403 int i915_sw_fence_await_sw_fence_gfp(struct i915_sw_fence *fence,
404 				     struct i915_sw_fence *signaler,
405 				     gfp_t gfp)
406 {
407 	return __i915_sw_fence_await_sw_fence(fence, signaler, NULL, gfp);
408 }
409 
410 struct i915_sw_dma_fence_cb_timer {
411 	struct i915_sw_dma_fence_cb base;
412 	struct dma_fence *dma;
413 	struct timer_list timer;
414 	struct irq_work work;
415 	struct rcu_head rcu;
416 };
417 
418 static void dma_i915_sw_fence_wake(struct dma_fence *dma,
419 				   struct dma_fence_cb *data)
420 {
421 	struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
422 
423 	i915_sw_fence_set_error_once(cb->fence, dma->error);
424 	i915_sw_fence_complete(cb->fence);
425 	kfree(cb);
426 }
427 
428 static void timer_i915_sw_fence_wake(struct timer_list *t)
429 {
430 	struct i915_sw_dma_fence_cb_timer *cb = from_timer(cb, t, timer);
431 	struct i915_sw_fence *fence;
432 
433 	fence = xchg(&cb->base.fence, NULL);
434 	if (!fence)
435 		return;
436 
437 	pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",
438 		  cb->dma->ops->get_driver_name(cb->dma),
439 		  cb->dma->ops->get_timeline_name(cb->dma),
440 		  cb->dma->seqno,
441 		  i915_sw_fence_debug_hint(fence));
442 
443 	i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
444 	i915_sw_fence_complete(fence);
445 }
446 
447 static void dma_i915_sw_fence_wake_timer(struct dma_fence *dma,
448 					 struct dma_fence_cb *data)
449 {
450 	struct i915_sw_dma_fence_cb_timer *cb =
451 		container_of(data, typeof(*cb), base.base);
452 	struct i915_sw_fence *fence;
453 
454 	fence = xchg(&cb->base.fence, NULL);
455 	if (fence) {
456 		i915_sw_fence_set_error_once(fence, dma->error);
457 		i915_sw_fence_complete(fence);
458 	}
459 
460 	irq_work_queue(&cb->work);
461 }
462 
463 static void irq_i915_sw_fence_work(struct irq_work *wrk)
464 {
465 	struct i915_sw_dma_fence_cb_timer *cb =
466 		container_of(wrk, typeof(*cb), work);
467 
468 	timer_shutdown_sync(&cb->timer);
469 	dma_fence_put(cb->dma);
470 
471 	kfree_rcu(cb, rcu);
472 }
473 
474 int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
475 				  struct dma_fence *dma,
476 				  unsigned long timeout,
477 				  gfp_t gfp)
478 {
479 	struct i915_sw_dma_fence_cb *cb;
480 	dma_fence_func_t func;
481 	int ret;
482 
483 	debug_fence_assert(fence);
484 	might_sleep_if(gfpflags_allow_blocking(gfp));
485 
486 	if (dma_fence_is_signaled(dma)) {
487 		i915_sw_fence_set_error_once(fence, dma->error);
488 		return 0;
489 	}
490 
491 	cb = kmalloc(timeout ?
492 		     sizeof(struct i915_sw_dma_fence_cb_timer) :
493 		     sizeof(struct i915_sw_dma_fence_cb),
494 		     gfp);
495 	if (!cb) {
496 		if (!gfpflags_allow_blocking(gfp))
497 			return -ENOMEM;
498 
499 		ret = dma_fence_wait(dma, false);
500 		if (ret)
501 			return ret;
502 
503 		i915_sw_fence_set_error_once(fence, dma->error);
504 		return 0;
505 	}
506 
507 	cb->fence = fence;
508 	i915_sw_fence_await(fence);
509 
510 	func = dma_i915_sw_fence_wake;
511 	if (timeout) {
512 		struct i915_sw_dma_fence_cb_timer *timer =
513 			container_of(cb, typeof(*timer), base);
514 
515 		timer->dma = dma_fence_get(dma);
516 		init_irq_work(&timer->work, irq_i915_sw_fence_work);
517 
518 		timer_setup(&timer->timer,
519 			    timer_i915_sw_fence_wake, TIMER_IRQSAFE);
520 		mod_timer(&timer->timer, round_jiffies_up(jiffies + timeout));
521 
522 		func = dma_i915_sw_fence_wake_timer;
523 	}
524 
525 	ret = dma_fence_add_callback(dma, &cb->base, func);
526 	if (ret == 0) {
527 		ret = 1;
528 	} else {
529 		func(dma, &cb->base);
530 		if (ret == -ENOENT) /* fence already signaled */
531 			ret = 0;
532 	}
533 
534 	return ret;
535 }
536 
537 static void __dma_i915_sw_fence_wake(struct dma_fence *dma,
538 				     struct dma_fence_cb *data)
539 {
540 	struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
541 
542 	i915_sw_fence_set_error_once(cb->fence, dma->error);
543 	i915_sw_fence_complete(cb->fence);
544 }
545 
546 int __i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
547 				    struct dma_fence *dma,
548 				    struct i915_sw_dma_fence_cb *cb)
549 {
550 	int ret;
551 
552 	debug_fence_assert(fence);
553 
554 	if (dma_fence_is_signaled(dma)) {
555 		i915_sw_fence_set_error_once(fence, dma->error);
556 		return 0;
557 	}
558 
559 	cb->fence = fence;
560 	i915_sw_fence_await(fence);
561 
562 	ret = 1;
563 	if (dma_fence_add_callback(dma, &cb->base, __dma_i915_sw_fence_wake)) {
564 		/* fence already signaled */
565 		__dma_i915_sw_fence_wake(dma, &cb->base);
566 		ret = 0;
567 	}
568 
569 	return ret;
570 }
571 
572 int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
573 				    struct dma_resv *resv,
574 				    bool write,
575 				    unsigned long timeout,
576 				    gfp_t gfp)
577 {
578 	struct dma_resv_iter cursor;
579 	struct dma_fence *f;
580 	int ret = 0, pending;
581 
582 	debug_fence_assert(fence);
583 	might_sleep_if(gfpflags_allow_blocking(gfp));
584 
585 	dma_resv_iter_begin(&cursor, resv, dma_resv_usage_rw(write));
586 	dma_resv_for_each_fence_unlocked(&cursor, f) {
587 		pending = i915_sw_fence_await_dma_fence(fence, f, timeout,
588 							gfp);
589 		if (pending < 0) {
590 			ret = pending;
591 			break;
592 		}
593 
594 		ret |= pending;
595 	}
596 	dma_resv_iter_end(&cursor);
597 	return ret;
598 }
599 
600 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
601 #include "selftests/lib_sw_fence.c"
602 #include "selftests/i915_sw_fence.c"
603 #endif
604