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
22static 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
32enum {
33 DEBUG_FENCE_IDLE = 0,
34 DEBUG_FENCE_NOTIFY,
35};
36
37static 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
44static 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
49static inline void debug_fence_init(struct i915_sw_fence *fence)
50{
51 debug_object_init(fence, &i915_sw_fence_debug_descr);
52}
53
54static inline __maybe_unused 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
59static inline void debug_fence_activate(struct i915_sw_fence *fence)
60{
61 debug_object_activate(fence, &i915_sw_fence_debug_descr);
62}
63
64static 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
70static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
71{
72 debug_object_deactivate(fence, &i915_sw_fence_debug_descr);
73}
74
75static inline void debug_fence_destroy(struct i915_sw_fence *fence)
76{
77 debug_object_destroy(fence, &i915_sw_fence_debug_descr);
78}
79
80static inline __maybe_unused 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
86static 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
93static inline void debug_fence_init(struct i915_sw_fence *fence)
94{
95}
96
97static inline __maybe_unused void debug_fence_init_onstack(struct i915_sw_fence *fence)
98{
99}
100
101static inline void debug_fence_activate(struct i915_sw_fence *fence)
102{
103}
104
105static inline void debug_fence_set_state(struct i915_sw_fence *fence,
106 int old, int new)
107{
108}
109
110static inline void debug_fence_deactivate(struct i915_sw_fence *fence)
111{
112}
113
114static inline void debug_fence_destroy(struct i915_sw_fence *fence)
115{
116}
117
118static inline __maybe_unused void debug_fence_free(struct i915_sw_fence *fence)
119{
120}
121
122static inline void debug_fence_assert(struct i915_sw_fence *fence)
123{
124}
125
126#endif
127
128static 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
135void i915_sw_fence_fini(struct i915_sw_fence *fence)
136{
137 debug_fence_free(fence);
138}
139#endif
140
141static 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(v: &fence->pending, i: -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(list: &pos->entry, head: 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(head: &extra))
181 break;
182
183 list_splice_tail_init(list: &extra, head: &x->head);
184 } while (1);
185 }
186 spin_unlock_irqrestore(lock: &x->lock, flags);
187
188 debug_fence_assert(fence);
189}
190
191static 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(v: &fence->pending))
197 return;
198
199 debug_fence_set_state(fence, old: DEBUG_FENCE_IDLE, new: DEBUG_FENCE_NOTIFY);
200
201 if (__i915_sw_fence_notify(fence, state: FENCE_COMPLETE) != NOTIFY_DONE)
202 return;
203
204 debug_fence_set_state(fence, old: DEBUG_FENCE_NOTIFY, new: 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, state: FENCE_FREE);
210}
211
212void 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
222bool 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(v: &fence->pending);
231 do {
232 if (pending < 1)
233 return false;
234 } while (!atomic_try_cmpxchg(v: &fence->pending, old: &pending, new: pending + 1));
235
236 return true;
237}
238
239void __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(wq_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
253void i915_sw_fence_reinit(struct i915_sw_fence *fence)
254{
255 debug_fence_init(fence);
256
257 atomic_set(v: &fence->pending, i: 1);
258 fence->error = 0;
259
260 I915_SW_FENCE_BUG_ON(!list_empty(&fence->wait.head));
261}
262
263void i915_sw_fence_commit(struct i915_sw_fence *fence)
264{
265 debug_fence_activate(fence);
266 i915_sw_fence_complete(fence);
267}
268
269static int i915_sw_fence_wake(wait_queue_entry_t *wq, unsigned mode, int flags, void *key)
270{
271 i915_sw_fence_set_error_once(fence: wq->private, error: flags);
272
273 list_del(entry: &wq->entry);
274 __i915_sw_fence_complete(fence: wq->private, continuation: key);
275
276 if (wq->flags & I915_SW_FENCE_FLAG_ALLOC)
277 kfree(objp: wq);
278 return 0;
279}
280
281#ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
282static 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
304static 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
319static 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
333static 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
340static 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(fence: signaler)) {
351 i915_sw_fence_set_error_once(fence, error: signaler->error);
352 return 0;
353 }
354
355 debug_fence_assert(fence: 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_flags: gfp))
366 return -ENOMEM;
367
368 i915_sw_fence_wait(fence: signaler);
369 i915_sw_fence_set_error_once(fence, error: signaler->error);
370 return 0;
371 }
372
373 pending |= I915_SW_FENCE_FLAG_ALLOC;
374 }
375
376 INIT_LIST_HEAD(list: &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(wq_head: &signaler->wait, wq_entry: wq);
386 pending = 1;
387 } else {
388 i915_sw_fence_wake(wq, mode: 0, flags: signaler->error, NULL);
389 pending = 0;
390 }
391 spin_unlock_irqrestore(lock: &signaler->wait.lock, flags);
392
393 return pending;
394}
395
396int 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, gfp: 0);
401}
402
403int 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
410struct 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
418static 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(fence: cb->fence, error: dma->error);
424 i915_sw_fence_complete(fence: cb->fence);
425 kfree(objp: cb);
426}
427
428static void timer_i915_sw_fence_wake(struct timer_list *t)
429{
430 struct i915_sw_dma_fence_cb_timer *cb = timer_container_of(cb, t,
431 timer);
432 struct i915_sw_fence *fence;
433 const char __rcu *timeline;
434 const char __rcu *driver;
435
436 fence = xchg(&cb->base.fence, NULL);
437 if (!fence)
438 return;
439
440 rcu_read_lock();
441 driver = dma_fence_driver_name(fence: cb->dma);
442 timeline = dma_fence_timeline_name(fence: cb->dma);
443 pr_notice("Asynchronous wait on fence %s:%s:%llx timed out (hint:%ps)\n",
444 rcu_dereference(driver),
445 rcu_dereference(timeline),
446 cb->dma->seqno,
447 i915_sw_fence_debug_hint(fence));
448 rcu_read_unlock();
449
450 i915_sw_fence_set_error_once(fence, error: -ETIMEDOUT);
451 i915_sw_fence_complete(fence);
452}
453
454static void dma_i915_sw_fence_wake_timer(struct dma_fence *dma,
455 struct dma_fence_cb *data)
456{
457 struct i915_sw_dma_fence_cb_timer *cb =
458 container_of(data, typeof(*cb), base.base);
459 struct i915_sw_fence *fence;
460
461 fence = xchg(&cb->base.fence, NULL);
462 if (fence) {
463 i915_sw_fence_set_error_once(fence, error: dma->error);
464 i915_sw_fence_complete(fence);
465 }
466
467 irq_work_queue(work: &cb->work);
468}
469
470static void irq_i915_sw_fence_work(struct irq_work *wrk)
471{
472 struct i915_sw_dma_fence_cb_timer *cb =
473 container_of(wrk, typeof(*cb), work);
474
475 timer_shutdown_sync(timer: &cb->timer);
476 dma_fence_put(fence: cb->dma);
477
478 kfree_rcu(cb, rcu);
479}
480
481int i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
482 struct dma_fence *dma,
483 unsigned long timeout,
484 gfp_t gfp)
485{
486 struct i915_sw_dma_fence_cb *cb;
487 dma_fence_func_t func;
488 int ret;
489
490 debug_fence_assert(fence);
491 might_sleep_if(gfpflags_allow_blocking(gfp));
492
493 if (dma_fence_is_signaled(fence: dma)) {
494 i915_sw_fence_set_error_once(fence, error: dma->error);
495 return 0;
496 }
497
498 cb = kmalloc(timeout ?
499 sizeof(struct i915_sw_dma_fence_cb_timer) :
500 sizeof(struct i915_sw_dma_fence_cb),
501 gfp);
502 if (!cb) {
503 if (!gfpflags_allow_blocking(gfp_flags: gfp))
504 return -ENOMEM;
505
506 ret = dma_fence_wait(fence: dma, intr: false);
507 if (ret)
508 return ret;
509
510 i915_sw_fence_set_error_once(fence, error: dma->error);
511 return 0;
512 }
513
514 cb->fence = fence;
515 i915_sw_fence_await(fence);
516
517 func = dma_i915_sw_fence_wake;
518 if (timeout) {
519 struct i915_sw_dma_fence_cb_timer *timer =
520 container_of(cb, typeof(*timer), base);
521
522 timer->dma = dma_fence_get(fence: dma);
523 init_irq_work(work: &timer->work, func: irq_i915_sw_fence_work);
524
525 timer_setup(&timer->timer,
526 timer_i915_sw_fence_wake, TIMER_IRQSAFE);
527 mod_timer(timer: &timer->timer, expires: round_jiffies_up(j: jiffies + timeout));
528
529 func = dma_i915_sw_fence_wake_timer;
530 }
531
532 ret = dma_fence_add_callback(fence: dma, cb: &cb->base, func);
533 if (ret == 0) {
534 ret = 1;
535 } else {
536 func(dma, &cb->base);
537 if (ret == -ENOENT) /* fence already signaled */
538 ret = 0;
539 }
540
541 return ret;
542}
543
544static void __dma_i915_sw_fence_wake(struct dma_fence *dma,
545 struct dma_fence_cb *data)
546{
547 struct i915_sw_dma_fence_cb *cb = container_of(data, typeof(*cb), base);
548
549 i915_sw_fence_set_error_once(fence: cb->fence, error: dma->error);
550 i915_sw_fence_complete(fence: cb->fence);
551}
552
553int __i915_sw_fence_await_dma_fence(struct i915_sw_fence *fence,
554 struct dma_fence *dma,
555 struct i915_sw_dma_fence_cb *cb)
556{
557 int ret;
558
559 debug_fence_assert(fence);
560
561 if (dma_fence_is_signaled(fence: dma)) {
562 i915_sw_fence_set_error_once(fence, error: dma->error);
563 return 0;
564 }
565
566 cb->fence = fence;
567 i915_sw_fence_await(fence);
568
569 ret = 1;
570 if (dma_fence_add_callback(fence: dma, cb: &cb->base, func: __dma_i915_sw_fence_wake)) {
571 /* fence already signaled */
572 __dma_i915_sw_fence_wake(dma, data: &cb->base);
573 ret = 0;
574 }
575
576 return ret;
577}
578
579int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
580 struct dma_resv *resv,
581 bool write,
582 unsigned long timeout,
583 gfp_t gfp)
584{
585 struct dma_resv_iter cursor;
586 struct dma_fence *f;
587 int ret = 0, pending;
588
589 debug_fence_assert(fence);
590 might_sleep_if(gfpflags_allow_blocking(gfp));
591
592 dma_resv_iter_begin(cursor: &cursor, obj: resv, usage: dma_resv_usage_rw(write));
593 dma_resv_for_each_fence_unlocked(&cursor, f) {
594 pending = i915_sw_fence_await_dma_fence(fence, dma: f, timeout,
595 gfp);
596 if (pending < 0) {
597 ret = pending;
598 break;
599 }
600
601 ret |= pending;
602 }
603 dma_resv_iter_end(cursor: &cursor);
604 return ret;
605}
606
607#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
608#include "selftests/lib_sw_fence.c"
609#include "selftests/i915_sw_fence.c"
610#endif
611