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 	BUG_ON(!fn);
245 
246 	__init_waitqueue_head(&fence->wait, name, key);
247 	fence->fn = fn;
248 #ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
249 	fence->flags = 0;
250 #endif
251 
252 	i915_sw_fence_reinit(fence);
253 }
254 
255 void i915_sw_fence_reinit(struct i915_sw_fence *fence)
256 {
257 	debug_fence_init(fence);
258 
259 	atomic_set(&fence->pending, 1);
260 	fence->error = 0;
261 
262 	I915_SW_FENCE_BUG_ON(!list_empty(&fence->wait.head));
263 }
264 
265 void i915_sw_fence_commit(struct i915_sw_fence *fence)
266 {
267 	debug_fence_activate(fence);
268 	i915_sw_fence_complete(fence);
269 }
270 
271 static int i915_sw_fence_wake(wait_queue_entry_t *wq, unsigned mode, int flags, void *key)
272 {
273 	i915_sw_fence_set_error_once(wq->private, flags);
274 
275 	list_del(&wq->entry);
276 	__i915_sw_fence_complete(wq->private, key);
277 
278 	if (wq->flags & I915_SW_FENCE_FLAG_ALLOC)
279 		kfree(wq);
280 	return 0;
281 }
282 
283 #ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
284 static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
285 				    const struct i915_sw_fence * const signaler)
286 {
287 	wait_queue_entry_t *wq;
288 
289 	if (__test_and_set_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
290 		return false;
291 
292 	if (fence == signaler)
293 		return true;
294 
295 	list_for_each_entry(wq, &fence->wait.head, entry) {
296 		if (wq->func != i915_sw_fence_wake)
297 			continue;
298 
299 		if (__i915_sw_fence_check_if_after(wq->private, signaler))
300 			return true;
301 	}
302 
303 	return false;
304 }
305 
306 static void __i915_sw_fence_clear_checked_bit(struct i915_sw_fence *fence)
307 {
308 	wait_queue_entry_t *wq;
309 
310 	if (!__test_and_clear_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
311 		return;
312 
313 	list_for_each_entry(wq, &fence->wait.head, entry) {
314 		if (wq->func != i915_sw_fence_wake)
315 			continue;
316 
317 		__i915_sw_fence_clear_checked_bit(wq->private);
318 	}
319 }
320 
321 static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
322 				  const struct i915_sw_fence * const signaler)
323 {
324 	unsigned long flags;
325 	bool err;
326 
327 	spin_lock_irqsave(&i915_sw_fence_lock, flags);
328 	err = __i915_sw_fence_check_if_after(fence, signaler);
329 	__i915_sw_fence_clear_checked_bit(fence);
330 	spin_unlock_irqrestore(&i915_sw_fence_lock, flags);
331 
332 	return err;
333 }
334 #else
335 static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
336 					 const struct i915_sw_fence * const signaler)
337 {
338 	return false;
339 }
340 #endif
341 
342 static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
343 					  struct i915_sw_fence *signaler,
344 					  wait_queue_entry_t *wq, gfp_t gfp)
345 {
346 	unsigned int pending;
347 	unsigned long flags;
348 
349 	debug_fence_assert(fence);
350 	might_sleep_if(gfpflags_allow_blocking(gfp));
351 
352 	if (i915_sw_fence_done(signaler)) {
353 		i915_sw_fence_set_error_once(fence, signaler->error);
354 		return 0;
355 	}
356 
357 	debug_fence_assert(signaler);
358 
359 	/* The dependency graph must be acyclic. */
360 	if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
361 		return -EINVAL;
362 
363 	pending = I915_SW_FENCE_FLAG_FENCE;
364 	if (!wq) {
365 		wq = kmalloc(sizeof(*wq), gfp);
366 		if (!wq) {
367 			if (!gfpflags_allow_blocking(gfp))
368 				return -ENOMEM;
369 
370 			i915_sw_fence_wait(signaler);
371 			i915_sw_fence_set_error_once(fence, signaler->error);
372 			return 0;
373 		}
374 
375 		pending |= I915_SW_FENCE_FLAG_ALLOC;
376 	}
377 
378 	INIT_LIST_HEAD(&wq->entry);
379 	wq->flags = pending;
380 	wq->func = i915_sw_fence_wake;
381 	wq->private = fence;
382 
383 	i915_sw_fence_await(fence);
384 
385 	spin_lock_irqsave(&signaler->wait.lock, flags);
386 	if (likely(!i915_sw_fence_done(signaler))) {
387 		__add_wait_queue_entry_tail(&signaler->wait, wq);
388 		pending = 1;
389 	} else {
390 		i915_sw_fence_wake(wq, 0, signaler->error, NULL);
391 		pending = 0;
392 	}
393 	spin_unlock_irqrestore(&signaler->wait.lock, flags);
394 
395 	return pending;
396 }
397 
398 int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
399 				 struct i915_sw_fence *signaler,
400 				 wait_queue_entry_t *wq)
401 {
402 	return __i915_sw_fence_await_sw_fence(fence, signaler, wq, 0);
403 }
404 
405 int i915_sw_fence_await_sw_fence_gfp(struct i915_sw_fence *fence,
406 				     struct i915_sw_fence *signaler,
407 				     gfp_t gfp)
408 {
409 	return __i915_sw_fence_await_sw_fence(fence, signaler, NULL, gfp);
410 }
411 
412 struct i915_sw_dma_fence_cb_timer {
413 	struct i915_sw_dma_fence_cb base;
414 	struct dma_fence *dma;
415 	struct timer_list timer;
416 	struct irq_work work;
417 	struct rcu_head rcu;
418 };
419 
420 static void dma_i915_sw_fence_wake(struct dma_fence *dma,
421 				   struct dma_fence_cb *data)
422 {
423 	struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
424 
425 	i915_sw_fence_set_error_once(cb->fence, dma->error);
426 	i915_sw_fence_complete(cb->fence);
427 	kfree(cb);
428 }
429 
430 static void timer_i915_sw_fence_wake(struct timer_list *t)
431 {
432 	struct i915_sw_dma_fence_cb_timer *cb = from_timer(cb, t, timer);
433 	struct i915_sw_fence *fence;
434 
435 	fence = xchg(&cb->base.fence, NULL);
436 	if (!fence)
437 		return;
438 
439 	pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",
440 		  cb->dma->ops->get_driver_name(cb->dma),
441 		  cb->dma->ops->get_timeline_name(cb->dma),
442 		  cb->dma->seqno,
443 		  i915_sw_fence_debug_hint(fence));
444 
445 	i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
446 	i915_sw_fence_complete(fence);
447 }
448 
449 static void dma_i915_sw_fence_wake_timer(struct dma_fence *dma,
450 					 struct dma_fence_cb *data)
451 {
452 	struct i915_sw_dma_fence_cb_timer *cb =
453 		container_of(data, typeof(*cb), base.base);
454 	struct i915_sw_fence *fence;
455 
456 	fence = xchg(&cb->base.fence, NULL);
457 	if (fence) {
458 		i915_sw_fence_set_error_once(fence, dma->error);
459 		i915_sw_fence_complete(fence);
460 	}
461 
462 	irq_work_queue(&cb->work);
463 }
464 
465 static void irq_i915_sw_fence_work(struct irq_work *wrk)
466 {
467 	struct i915_sw_dma_fence_cb_timer *cb =
468 		container_of(wrk, typeof(*cb), work);
469 
470 	del_timer_sync(&cb->timer);
471 	dma_fence_put(cb->dma);
472 
473 	kfree_rcu(cb, rcu);
474 }
475 
476 int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
477 				  struct dma_fence *dma,
478 				  unsigned long timeout,
479 				  gfp_t gfp)
480 {
481 	struct i915_sw_dma_fence_cb *cb;
482 	dma_fence_func_t func;
483 	int ret;
484 
485 	debug_fence_assert(fence);
486 	might_sleep_if(gfpflags_allow_blocking(gfp));
487 
488 	if (dma_fence_is_signaled(dma)) {
489 		i915_sw_fence_set_error_once(fence, dma->error);
490 		return 0;
491 	}
492 
493 	cb = kmalloc(timeout ?
494 		     sizeof(struct i915_sw_dma_fence_cb_timer) :
495 		     sizeof(struct i915_sw_dma_fence_cb),
496 		     gfp);
497 	if (!cb) {
498 		if (!gfpflags_allow_blocking(gfp))
499 			return -ENOMEM;
500 
501 		ret = dma_fence_wait(dma, false);
502 		if (ret)
503 			return ret;
504 
505 		i915_sw_fence_set_error_once(fence, dma->error);
506 		return 0;
507 	}
508 
509 	cb->fence = fence;
510 	i915_sw_fence_await(fence);
511 
512 	func = dma_i915_sw_fence_wake;
513 	if (timeout) {
514 		struct i915_sw_dma_fence_cb_timer *timer =
515 			container_of(cb, typeof(*timer), base);
516 
517 		timer->dma = dma_fence_get(dma);
518 		init_irq_work(&timer->work, irq_i915_sw_fence_work);
519 
520 		timer_setup(&timer->timer,
521 			    timer_i915_sw_fence_wake, TIMER_IRQSAFE);
522 		mod_timer(&timer->timer, round_jiffies_up(jiffies + timeout));
523 
524 		func = dma_i915_sw_fence_wake_timer;
525 	}
526 
527 	ret = dma_fence_add_callback(dma, &cb->base, func);
528 	if (ret == 0) {
529 		ret = 1;
530 	} else {
531 		func(dma, &cb->base);
532 		if (ret == -ENOENT) /* fence already signaled */
533 			ret = 0;
534 	}
535 
536 	return ret;
537 }
538 
539 static void __dma_i915_sw_fence_wake(struct dma_fence *dma,
540 				     struct dma_fence_cb *data)
541 {
542 	struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
543 
544 	i915_sw_fence_set_error_once(cb->fence, dma->error);
545 	i915_sw_fence_complete(cb->fence);
546 }
547 
548 int __i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
549 				    struct dma_fence *dma,
550 				    struct i915_sw_dma_fence_cb *cb)
551 {
552 	int ret;
553 
554 	debug_fence_assert(fence);
555 
556 	if (dma_fence_is_signaled(dma)) {
557 		i915_sw_fence_set_error_once(fence, dma->error);
558 		return 0;
559 	}
560 
561 	cb->fence = fence;
562 	i915_sw_fence_await(fence);
563 
564 	ret = 1;
565 	if (dma_fence_add_callback(dma, &cb->base, __dma_i915_sw_fence_wake)) {
566 		/* fence already signaled */
567 		__dma_i915_sw_fence_wake(dma, &cb->base);
568 		ret = 0;
569 	}
570 
571 	return ret;
572 }
573 
574 int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
575 				    struct dma_resv *resv,
576 				    const struct dma_fence_ops *exclude,
577 				    bool write,
578 				    unsigned long timeout,
579 				    gfp_t gfp)
580 {
581 	struct dma_resv_iter cursor;
582 	struct dma_fence *f;
583 	int ret = 0, pending;
584 
585 	debug_fence_assert(fence);
586 	might_sleep_if(gfpflags_allow_blocking(gfp));
587 
588 	dma_resv_iter_begin(&cursor, resv, write);
589 	dma_resv_for_each_fence_unlocked(&cursor, f) {
590 		pending = i915_sw_fence_await_dma_fence(fence, f, timeout,
591 							gfp);
592 		if (pending < 0) {
593 			ret = pending;
594 			break;
595 		}
596 
597 		ret |= pending;
598 	}
599 	dma_resv_iter_end(&cursor);
600 	return ret;
601 }
602 
603 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
604 #include "selftests/lib_sw_fence.c"
605 #include "selftests/i915_sw_fence.c"
606 #endif
607