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 #define I915_SW_FENCE_FLAG_ALLOC BIT(3) /* after WQ_FLAG_* for safety */
22 
23 static DEFINE_SPINLOCK(i915_sw_fence_lock);
24 
25 enum {
26 	DEBUG_FENCE_IDLE = 0,
27 	DEBUG_FENCE_NOTIFY,
28 };
29 
30 static void *i915_sw_fence_debug_hint(void *addr)
31 {
32 	return (void *)(((struct i915_sw_fence *)addr)->flags & I915_SW_FENCE_MASK);
33 }
34 
35 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
36 
37 static struct debug_obj_descr i915_sw_fence_debug_descr = {
38 	.name = "i915_sw_fence",
39 	.debug_hint = i915_sw_fence_debug_hint,
40 };
41 
42 static inline void debug_fence_init(struct i915_sw_fence *fence)
43 {
44 	debug_object_init(fence, &i915_sw_fence_debug_descr);
45 }
46 
47 static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
48 {
49 	debug_object_init_on_stack(fence, &i915_sw_fence_debug_descr);
50 }
51 
52 static inline void debug_fence_activate(struct i915_sw_fence *fence)
53 {
54 	debug_object_activate(fence, &i915_sw_fence_debug_descr);
55 }
56 
57 static inline void debug_fence_set_state(struct i915_sw_fence *fence,
58 					 int old, int new)
59 {
60 	debug_object_active_state(fence, &i915_sw_fence_debug_descr, old, new);
61 }
62 
63 static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
64 {
65 	debug_object_deactivate(fence, &i915_sw_fence_debug_descr);
66 }
67 
68 static inline void debug_fence_destroy(struct i915_sw_fence *fence)
69 {
70 	debug_object_destroy(fence, &i915_sw_fence_debug_descr);
71 }
72 
73 static inline void debug_fence_free(struct i915_sw_fence *fence)
74 {
75 	debug_object_free(fence, &i915_sw_fence_debug_descr);
76 	smp_wmb(); /* flush the change in state before reallocation */
77 }
78 
79 static inline void debug_fence_assert(struct i915_sw_fence *fence)
80 {
81 	debug_object_assert_init(fence, &i915_sw_fence_debug_descr);
82 }
83 
84 #else
85 
86 static inline void debug_fence_init(struct i915_sw_fence *fence)
87 {
88 }
89 
90 static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
91 {
92 }
93 
94 static inline void debug_fence_activate(struct i915_sw_fence *fence)
95 {
96 }
97 
98 static inline void debug_fence_set_state(struct i915_sw_fence *fence,
99 					 int old, int new)
100 {
101 }
102 
103 static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
104 {
105 }
106 
107 static inline void debug_fence_destroy(struct i915_sw_fence *fence)
108 {
109 }
110 
111 static inline void debug_fence_free(struct i915_sw_fence *fence)
112 {
113 }
114 
115 static inline void debug_fence_assert(struct i915_sw_fence *fence)
116 {
117 }
118 
119 #endif
120 
121 static int __i915_sw_fence_notify(struct i915_sw_fence *fence,
122 				  enum i915_sw_fence_notify state)
123 {
124 	i915_sw_fence_notify_t fn;
125 
126 	fn = (i915_sw_fence_notify_t)(fence->flags & I915_SW_FENCE_MASK);
127 	return fn(fence, state);
128 }
129 
130 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
131 void i915_sw_fence_fini(struct i915_sw_fence *fence)
132 {
133 	debug_fence_free(fence);
134 }
135 #endif
136 
137 static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
138 					struct list_head *continuation)
139 {
140 	wait_queue_head_t *x = &fence->wait;
141 	wait_queue_entry_t *pos, *next;
142 	unsigned long flags;
143 
144 	debug_fence_deactivate(fence);
145 	atomic_set_release(&fence->pending, -1); /* 0 -> -1 [done] */
146 
147 	/*
148 	 * To prevent unbounded recursion as we traverse the graph of
149 	 * i915_sw_fences, we move the entry list from this, the next ready
150 	 * fence, to the tail of the original fence's entry list
151 	 * (and so added to the list to be woken).
152 	 */
153 
154 	spin_lock_irqsave_nested(&x->lock, flags, 1 + !!continuation);
155 	if (continuation) {
156 		list_for_each_entry_safe(pos, next, &x->head, entry) {
157 			if (pos->func == autoremove_wake_function)
158 				pos->func(pos, TASK_NORMAL, 0, continuation);
159 			else
160 				list_move_tail(&pos->entry, continuation);
161 		}
162 	} else {
163 		LIST_HEAD(extra);
164 
165 		do {
166 			list_for_each_entry_safe(pos, next, &x->head, entry) {
167 				pos->func(pos,
168 					  TASK_NORMAL, fence->error,
169 					  &extra);
170 			}
171 
172 			if (list_empty(&extra))
173 				break;
174 
175 			list_splice_tail_init(&extra, &x->head);
176 		} while (1);
177 	}
178 	spin_unlock_irqrestore(&x->lock, flags);
179 
180 	debug_fence_assert(fence);
181 }
182 
183 static void __i915_sw_fence_complete(struct i915_sw_fence *fence,
184 				     struct list_head *continuation)
185 {
186 	debug_fence_assert(fence);
187 
188 	if (!atomic_dec_and_test(&fence->pending))
189 		return;
190 
191 	debug_fence_set_state(fence, DEBUG_FENCE_IDLE, DEBUG_FENCE_NOTIFY);
192 
193 	if (__i915_sw_fence_notify(fence, FENCE_COMPLETE) != NOTIFY_DONE)
194 		return;
195 
196 	debug_fence_set_state(fence, DEBUG_FENCE_NOTIFY, DEBUG_FENCE_IDLE);
197 
198 	__i915_sw_fence_wake_up_all(fence, continuation);
199 
200 	debug_fence_destroy(fence);
201 	__i915_sw_fence_notify(fence, FENCE_FREE);
202 }
203 
204 void i915_sw_fence_complete(struct i915_sw_fence *fence)
205 {
206 	debug_fence_assert(fence);
207 
208 	if (WARN_ON(i915_sw_fence_done(fence)))
209 		return;
210 
211 	__i915_sw_fence_complete(fence, NULL);
212 }
213 
214 bool i915_sw_fence_await(struct i915_sw_fence *fence)
215 {
216 	int pending;
217 
218 	/*
219 	 * It is only safe to add a new await to the fence while it has
220 	 * not yet been signaled (i.e. there are still existing signalers).
221 	 */
222 	pending = atomic_read(&fence->pending);
223 	do {
224 		if (pending < 1)
225 			return false;
226 	} while (!atomic_try_cmpxchg(&fence->pending, &pending, pending + 1));
227 
228 	return true;
229 }
230 
231 void __i915_sw_fence_init(struct i915_sw_fence *fence,
232 			  i915_sw_fence_notify_t fn,
233 			  const char *name,
234 			  struct lock_class_key *key)
235 {
236 	BUG_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK);
237 
238 	__init_waitqueue_head(&fence->wait, name, key);
239 	fence->flags = (unsigned long)fn;
240 
241 	i915_sw_fence_reinit(fence);
242 }
243 
244 void i915_sw_fence_reinit(struct i915_sw_fence *fence)
245 {
246 	debug_fence_init(fence);
247 
248 	atomic_set(&fence->pending, 1);
249 	fence->error = 0;
250 
251 	I915_SW_FENCE_BUG_ON(!fence->flags);
252 	I915_SW_FENCE_BUG_ON(!list_empty(&fence->wait.head));
253 }
254 
255 void i915_sw_fence_commit(struct i915_sw_fence *fence)
256 {
257 	debug_fence_activate(fence);
258 	i915_sw_fence_complete(fence);
259 }
260 
261 static int i915_sw_fence_wake(wait_queue_entry_t *wq, unsigned mode, int flags, void *key)
262 {
263 	i915_sw_fence_set_error_once(wq->private, flags);
264 
265 	list_del(&wq->entry);
266 	__i915_sw_fence_complete(wq->private, key);
267 
268 	if (wq->flags & I915_SW_FENCE_FLAG_ALLOC)
269 		kfree(wq);
270 	return 0;
271 }
272 
273 static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
274 				    const struct i915_sw_fence * const signaler)
275 {
276 	wait_queue_entry_t *wq;
277 
278 	if (__test_and_set_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
279 		return false;
280 
281 	if (fence == signaler)
282 		return true;
283 
284 	list_for_each_entry(wq, &fence->wait.head, entry) {
285 		if (wq->func != i915_sw_fence_wake)
286 			continue;
287 
288 		if (__i915_sw_fence_check_if_after(wq->private, signaler))
289 			return true;
290 	}
291 
292 	return false;
293 }
294 
295 static void __i915_sw_fence_clear_checked_bit(struct i915_sw_fence *fence)
296 {
297 	wait_queue_entry_t *wq;
298 
299 	if (!__test_and_clear_bit(I915_SW_FENCE_CHECKED_BIT, &fence->flags))
300 		return;
301 
302 	list_for_each_entry(wq, &fence->wait.head, entry) {
303 		if (wq->func != i915_sw_fence_wake)
304 			continue;
305 
306 		__i915_sw_fence_clear_checked_bit(wq->private);
307 	}
308 }
309 
310 static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
311 				  const struct i915_sw_fence * const signaler)
312 {
313 	unsigned long flags;
314 	bool err;
315 
316 	if (!IS_ENABLED(CONFIG_DRM_I915_SW_FENCE_CHECK_DAG))
317 		return false;
318 
319 	spin_lock_irqsave(&i915_sw_fence_lock, flags);
320 	err = __i915_sw_fence_check_if_after(fence, signaler);
321 	__i915_sw_fence_clear_checked_bit(fence);
322 	spin_unlock_irqrestore(&i915_sw_fence_lock, flags);
323 
324 	return err;
325 }
326 
327 static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
328 					  struct i915_sw_fence *signaler,
329 					  wait_queue_entry_t *wq, gfp_t gfp)
330 {
331 	unsigned long flags;
332 	int pending;
333 
334 	debug_fence_assert(fence);
335 	might_sleep_if(gfpflags_allow_blocking(gfp));
336 
337 	if (i915_sw_fence_done(signaler)) {
338 		i915_sw_fence_set_error_once(fence, signaler->error);
339 		return 0;
340 	}
341 
342 	debug_fence_assert(signaler);
343 
344 	/* The dependency graph must be acyclic. */
345 	if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
346 		return -EINVAL;
347 
348 	pending = 0;
349 	if (!wq) {
350 		wq = kmalloc(sizeof(*wq), gfp);
351 		if (!wq) {
352 			if (!gfpflags_allow_blocking(gfp))
353 				return -ENOMEM;
354 
355 			i915_sw_fence_wait(signaler);
356 			i915_sw_fence_set_error_once(fence, signaler->error);
357 			return 0;
358 		}
359 
360 		pending |= I915_SW_FENCE_FLAG_ALLOC;
361 	}
362 
363 	INIT_LIST_HEAD(&wq->entry);
364 	wq->flags = pending;
365 	wq->func = i915_sw_fence_wake;
366 	wq->private = fence;
367 
368 	i915_sw_fence_await(fence);
369 
370 	spin_lock_irqsave(&signaler->wait.lock, flags);
371 	if (likely(!i915_sw_fence_done(signaler))) {
372 		__add_wait_queue_entry_tail(&signaler->wait, wq);
373 		pending = 1;
374 	} else {
375 		i915_sw_fence_wake(wq, 0, signaler->error, NULL);
376 		pending = 0;
377 	}
378 	spin_unlock_irqrestore(&signaler->wait.lock, flags);
379 
380 	return pending;
381 }
382 
383 int i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
384 				 struct i915_sw_fence *signaler,
385 				 wait_queue_entry_t *wq)
386 {
387 	return __i915_sw_fence_await_sw_fence(fence, signaler, wq, 0);
388 }
389 
390 int i915_sw_fence_await_sw_fence_gfp(struct i915_sw_fence *fence,
391 				     struct i915_sw_fence *signaler,
392 				     gfp_t gfp)
393 {
394 	return __i915_sw_fence_await_sw_fence(fence, signaler, NULL, gfp);
395 }
396 
397 struct i915_sw_dma_fence_cb_timer {
398 	struct i915_sw_dma_fence_cb base;
399 	struct dma_fence *dma;
400 	struct timer_list timer;
401 	struct irq_work work;
402 	struct rcu_head rcu;
403 };
404 
405 static void dma_i915_sw_fence_wake(struct dma_fence *dma,
406 				   struct dma_fence_cb *data)
407 {
408 	struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
409 
410 	i915_sw_fence_set_error_once(cb->fence, dma->error);
411 	i915_sw_fence_complete(cb->fence);
412 	kfree(cb);
413 }
414 
415 static void timer_i915_sw_fence_wake(struct timer_list *t)
416 {
417 	struct i915_sw_dma_fence_cb_timer *cb = from_timer(cb, t, timer);
418 	struct i915_sw_fence *fence;
419 
420 	fence = xchg(&cb->base.fence, NULL);
421 	if (!fence)
422 		return;
423 
424 	pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",
425 		  cb->dma->ops->get_driver_name(cb->dma),
426 		  cb->dma->ops->get_timeline_name(cb->dma),
427 		  cb->dma->seqno,
428 		  i915_sw_fence_debug_hint(fence));
429 
430 	i915_sw_fence_set_error_once(fence, -ETIMEDOUT);
431 	i915_sw_fence_complete(fence);
432 }
433 
434 static void dma_i915_sw_fence_wake_timer(struct dma_fence *dma,
435 					 struct dma_fence_cb *data)
436 {
437 	struct i915_sw_dma_fence_cb_timer *cb =
438 		container_of(data, typeof(*cb), base.base);
439 	struct i915_sw_fence *fence;
440 
441 	fence = xchg(&cb->base.fence, NULL);
442 	if (fence) {
443 		i915_sw_fence_set_error_once(fence, dma->error);
444 		i915_sw_fence_complete(fence);
445 	}
446 
447 	irq_work_queue(&cb->work);
448 }
449 
450 static void irq_i915_sw_fence_work(struct irq_work *wrk)
451 {
452 	struct i915_sw_dma_fence_cb_timer *cb =
453 		container_of(wrk, typeof(*cb), work);
454 
455 	del_timer_sync(&cb->timer);
456 	dma_fence_put(cb->dma);
457 
458 	kfree_rcu(cb, rcu);
459 }
460 
461 int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
462 				  struct dma_fence *dma,
463 				  unsigned long timeout,
464 				  gfp_t gfp)
465 {
466 	struct i915_sw_dma_fence_cb *cb;
467 	dma_fence_func_t func;
468 	int ret;
469 
470 	debug_fence_assert(fence);
471 	might_sleep_if(gfpflags_allow_blocking(gfp));
472 
473 	if (dma_fence_is_signaled(dma)) {
474 		i915_sw_fence_set_error_once(fence, dma->error);
475 		return 0;
476 	}
477 
478 	cb = kmalloc(timeout ?
479 		     sizeof(struct i915_sw_dma_fence_cb_timer) :
480 		     sizeof(struct i915_sw_dma_fence_cb),
481 		     gfp);
482 	if (!cb) {
483 		if (!gfpflags_allow_blocking(gfp))
484 			return -ENOMEM;
485 
486 		ret = dma_fence_wait(dma, false);
487 		if (ret)
488 			return ret;
489 
490 		i915_sw_fence_set_error_once(fence, dma->error);
491 		return 0;
492 	}
493 
494 	cb->fence = fence;
495 	i915_sw_fence_await(fence);
496 
497 	func = dma_i915_sw_fence_wake;
498 	if (timeout) {
499 		struct i915_sw_dma_fence_cb_timer *timer =
500 			container_of(cb, typeof(*timer), base);
501 
502 		timer->dma = dma_fence_get(dma);
503 		init_irq_work(&timer->work, irq_i915_sw_fence_work);
504 
505 		timer_setup(&timer->timer,
506 			    timer_i915_sw_fence_wake, TIMER_IRQSAFE);
507 		mod_timer(&timer->timer, round_jiffies_up(jiffies + timeout));
508 
509 		func = dma_i915_sw_fence_wake_timer;
510 	}
511 
512 	ret = dma_fence_add_callback(dma, &cb->base, func);
513 	if (ret == 0) {
514 		ret = 1;
515 	} else {
516 		func(dma, &cb->base);
517 		if (ret == -ENOENT) /* fence already signaled */
518 			ret = 0;
519 	}
520 
521 	return ret;
522 }
523 
524 static void __dma_i915_sw_fence_wake(struct dma_fence *dma,
525 				     struct dma_fence_cb *data)
526 {
527 	struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
528 
529 	i915_sw_fence_set_error_once(cb->fence, dma->error);
530 	i915_sw_fence_complete(cb->fence);
531 }
532 
533 int __i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
534 				    struct dma_fence *dma,
535 				    struct i915_sw_dma_fence_cb *cb)
536 {
537 	int ret;
538 
539 	debug_fence_assert(fence);
540 
541 	if (dma_fence_is_signaled(dma)) {
542 		i915_sw_fence_set_error_once(fence, dma->error);
543 		return 0;
544 	}
545 
546 	cb->fence = fence;
547 	i915_sw_fence_await(fence);
548 
549 	ret = 1;
550 	if (dma_fence_add_callback(dma, &cb->base, __dma_i915_sw_fence_wake)) {
551 		/* fence already signaled */
552 		__dma_i915_sw_fence_wake(dma, &cb->base);
553 		ret = 0;
554 	}
555 
556 	return ret;
557 }
558 
559 int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
560 				    struct dma_resv *resv,
561 				    const struct dma_fence_ops *exclude,
562 				    bool write,
563 				    unsigned long timeout,
564 				    gfp_t gfp)
565 {
566 	struct dma_fence *excl;
567 	int ret = 0, pending;
568 
569 	debug_fence_assert(fence);
570 	might_sleep_if(gfpflags_allow_blocking(gfp));
571 
572 	if (write) {
573 		struct dma_fence **shared;
574 		unsigned int count, i;
575 
576 		ret = dma_resv_get_fences_rcu(resv, &excl, &count, &shared);
577 		if (ret)
578 			return ret;
579 
580 		for (i = 0; i < count; i++) {
581 			if (shared[i]->ops == exclude)
582 				continue;
583 
584 			pending = i915_sw_fence_await_dma_fence(fence,
585 								shared[i],
586 								timeout,
587 								gfp);
588 			if (pending < 0) {
589 				ret = pending;
590 				break;
591 			}
592 
593 			ret |= pending;
594 		}
595 
596 		for (i = 0; i < count; i++)
597 			dma_fence_put(shared[i]);
598 		kfree(shared);
599 	} else {
600 		excl = dma_resv_get_excl_rcu(resv);
601 	}
602 
603 	if (ret >= 0 && excl && excl->ops != exclude) {
604 		pending = i915_sw_fence_await_dma_fence(fence,
605 							excl,
606 							timeout,
607 							gfp);
608 		if (pending < 0)
609 			ret = pending;
610 		else
611 			ret |= pending;
612 	}
613 
614 	dma_fence_put(excl);
615 
616 	return ret;
617 }
618 
619 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
620 #include "selftests/lib_sw_fence.c"
621 #include "selftests/i915_sw_fence.c"
622 #endif
623