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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Module-based API test facility for ww_mutexes
4 */
5
6#include <linux/kernel.h>
7
8#include <linux/completion.h>
9#include <linux/delay.h>
10#include <linux/kthread.h>
11#include <linux/module.h>
12#include <linux/random.h>
13#include <linux/slab.h>
14#include <linux/ww_mutex.h>
15
16static DEFINE_WD_CLASS(ww_class);
17struct workqueue_struct *wq;
18
19#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
20#define ww_acquire_init_noinject(a, b) do { \
21 ww_acquire_init((a), (b)); \
22 (a)->deadlock_inject_countdown = ~0U; \
23 } while (0)
24#else
25#define ww_acquire_init_noinject(a, b) ww_acquire_init((a), (b))
26#endif
27
28struct test_mutex {
29 struct work_struct work;
30 struct ww_mutex mutex;
31 struct completion ready, go, done;
32 unsigned int flags;
33};
34
35#define TEST_MTX_SPIN BIT(0)
36#define TEST_MTX_TRY BIT(1)
37#define TEST_MTX_CTX BIT(2)
38#define __TEST_MTX_LAST BIT(3)
39
40static void test_mutex_work(struct work_struct *work)
41{
42 struct test_mutex *mtx = container_of(work, typeof(*mtx), work);
43
44 complete(&mtx->ready);
45 wait_for_completion(&mtx->go);
46
47 if (mtx->flags & TEST_MTX_TRY) {
48 while (!ww_mutex_trylock(&mtx->mutex, NULL))
49 cond_resched();
50 } else {
51 ww_mutex_lock(&mtx->mutex, NULL);
52 }
53 complete(&mtx->done);
54 ww_mutex_unlock(&mtx->mutex);
55}
56
57static int __test_mutex(unsigned int flags)
58{
59#define TIMEOUT (HZ / 16)
60 struct test_mutex mtx;
61 struct ww_acquire_ctx ctx;
62 int ret;
63
64 ww_mutex_init(&mtx.mutex, &ww_class);
65 ww_acquire_init(&ctx, &ww_class);
66
67 INIT_WORK_ONSTACK(&mtx.work, test_mutex_work);
68 init_completion(&mtx.ready);
69 init_completion(&mtx.go);
70 init_completion(&mtx.done);
71 mtx.flags = flags;
72
73 schedule_work(&mtx.work);
74
75 wait_for_completion(&mtx.ready);
76 ww_mutex_lock(&mtx.mutex, (flags & TEST_MTX_CTX) ? &ctx : NULL);
77 complete(&mtx.go);
78 if (flags & TEST_MTX_SPIN) {
79 unsigned long timeout = jiffies + TIMEOUT;
80
81 ret = 0;
82 do {
83 if (completion_done(&mtx.done)) {
84 ret = -EINVAL;
85 break;
86 }
87 cond_resched();
88 } while (time_before(jiffies, timeout));
89 } else {
90 ret = wait_for_completion_timeout(&mtx.done, TIMEOUT);
91 }
92 ww_mutex_unlock(&mtx.mutex);
93 ww_acquire_fini(&ctx);
94
95 if (ret) {
96 pr_err("%s(flags=%x): mutual exclusion failure\n",
97 __func__, flags);
98 ret = -EINVAL;
99 }
100
101 flush_work(&mtx.work);
102 destroy_work_on_stack(&mtx.work);
103 return ret;
104#undef TIMEOUT
105}
106
107static int test_mutex(void)
108{
109 int ret;
110 int i;
111
112 for (i = 0; i < __TEST_MTX_LAST; i++) {
113 ret = __test_mutex(i);
114 if (ret)
115 return ret;
116 }
117
118 return 0;
119}
120
121static int test_aa(bool trylock)
122{
123 struct ww_mutex mutex;
124 struct ww_acquire_ctx ctx;
125 int ret;
126 const char *from = trylock ? "trylock" : "lock";
127
128 ww_mutex_init(&mutex, &ww_class);
129 ww_acquire_init(&ctx, &ww_class);
130
131 if (!trylock) {
132 ret = ww_mutex_lock(&mutex, &ctx);
133 if (ret) {
134 pr_err("%s: initial lock failed!\n", __func__);
135 goto out;
136 }
137 } else {
138 ret = !ww_mutex_trylock(&mutex, &ctx);
139 if (ret) {
140 pr_err("%s: initial trylock failed!\n", __func__);
141 goto out;
142 }
143 }
144
145 if (ww_mutex_trylock(&mutex, NULL)) {
146 pr_err("%s: trylocked itself without context from %s!\n", __func__, from);
147 ww_mutex_unlock(&mutex);
148 ret = -EINVAL;
149 goto out;
150 }
151
152 if (ww_mutex_trylock(&mutex, &ctx)) {
153 pr_err("%s: trylocked itself with context from %s!\n", __func__, from);
154 ww_mutex_unlock(&mutex);
155 ret = -EINVAL;
156 goto out;
157 }
158
159 ret = ww_mutex_lock(&mutex, &ctx);
160 if (ret != -EALREADY) {
161 pr_err("%s: missed deadlock for recursing, ret=%d from %s\n",
162 __func__, ret, from);
163 if (!ret)
164 ww_mutex_unlock(&mutex);
165 ret = -EINVAL;
166 goto out;
167 }
168
169 ww_mutex_unlock(&mutex);
170 ret = 0;
171out:
172 ww_acquire_fini(&ctx);
173 return ret;
174}
175
176struct test_abba {
177 struct work_struct work;
178 struct ww_mutex a_mutex;
179 struct ww_mutex b_mutex;
180 struct completion a_ready;
181 struct completion b_ready;
182 bool resolve, trylock;
183 int result;
184};
185
186static void test_abba_work(struct work_struct *work)
187{
188 struct test_abba *abba = container_of(work, typeof(*abba), work);
189 struct ww_acquire_ctx ctx;
190 int err;
191
192 ww_acquire_init_noinject(&ctx, &ww_class);
193 if (!abba->trylock)
194 ww_mutex_lock(&abba->b_mutex, &ctx);
195 else
196 WARN_ON(!ww_mutex_trylock(&abba->b_mutex, &ctx));
197
198 WARN_ON(READ_ONCE(abba->b_mutex.ctx) != &ctx);
199
200 complete(&abba->b_ready);
201 wait_for_completion(&abba->a_ready);
202
203 err = ww_mutex_lock(&abba->a_mutex, &ctx);
204 if (abba->resolve && err == -EDEADLK) {
205 ww_mutex_unlock(&abba->b_mutex);
206 ww_mutex_lock_slow(&abba->a_mutex, &ctx);
207 err = ww_mutex_lock(&abba->b_mutex, &ctx);
208 }
209
210 if (!err)
211 ww_mutex_unlock(&abba->a_mutex);
212 ww_mutex_unlock(&abba->b_mutex);
213 ww_acquire_fini(&ctx);
214
215 abba->result = err;
216}
217
218static int test_abba(bool trylock, bool resolve)
219{
220 struct test_abba abba;
221 struct ww_acquire_ctx ctx;
222 int err, ret;
223
224 ww_mutex_init(&abba.a_mutex, &ww_class);
225 ww_mutex_init(&abba.b_mutex, &ww_class);
226 INIT_WORK_ONSTACK(&abba.work, test_abba_work);
227 init_completion(&abba.a_ready);
228 init_completion(&abba.b_ready);
229 abba.trylock = trylock;
230 abba.resolve = resolve;
231
232 schedule_work(&abba.work);
233
234 ww_acquire_init_noinject(&ctx, &ww_class);
235 if (!trylock)
236 ww_mutex_lock(&abba.a_mutex, &ctx);
237 else
238 WARN_ON(!ww_mutex_trylock(&abba.a_mutex, &ctx));
239
240 WARN_ON(READ_ONCE(abba.a_mutex.ctx) != &ctx);
241
242 complete(&abba.a_ready);
243 wait_for_completion(&abba.b_ready);
244
245 err = ww_mutex_lock(&abba.b_mutex, &ctx);
246 if (resolve && err == -EDEADLK) {
247 ww_mutex_unlock(&abba.a_mutex);
248 ww_mutex_lock_slow(&abba.b_mutex, &ctx);
249 err = ww_mutex_lock(&abba.a_mutex, &ctx);
250 }
251
252 if (!err)
253 ww_mutex_unlock(&abba.b_mutex);
254 ww_mutex_unlock(&abba.a_mutex);
255 ww_acquire_fini(&ctx);
256
257 flush_work(&abba.work);
258 destroy_work_on_stack(&abba.work);
259
260 ret = 0;
261 if (resolve) {
262 if (err || abba.result) {
263 pr_err("%s: failed to resolve ABBA deadlock, A err=%d, B err=%d\n",
264 __func__, err, abba.result);
265 ret = -EINVAL;
266 }
267 } else {
268 if (err != -EDEADLK && abba.result != -EDEADLK) {
269 pr_err("%s: missed ABBA deadlock, A err=%d, B err=%d\n",
270 __func__, err, abba.result);
271 ret = -EINVAL;
272 }
273 }
274 return ret;
275}
276
277struct test_cycle {
278 struct work_struct work;
279 struct ww_mutex a_mutex;
280 struct ww_mutex *b_mutex;
281 struct completion *a_signal;
282 struct completion b_signal;
283 int result;
284};
285
286static void test_cycle_work(struct work_struct *work)
287{
288 struct test_cycle *cycle = container_of(work, typeof(*cycle), work);
289 struct ww_acquire_ctx ctx;
290 int err, erra = 0;
291
292 ww_acquire_init_noinject(&ctx, &ww_class);
293 ww_mutex_lock(&cycle->a_mutex, &ctx);
294
295 complete(cycle->a_signal);
296 wait_for_completion(&cycle->b_signal);
297
298 err = ww_mutex_lock(cycle->b_mutex, &ctx);
299 if (err == -EDEADLK) {
300 err = 0;
301 ww_mutex_unlock(&cycle->a_mutex);
302 ww_mutex_lock_slow(cycle->b_mutex, &ctx);
303 erra = ww_mutex_lock(&cycle->a_mutex, &ctx);
304 }
305
306 if (!err)
307 ww_mutex_unlock(cycle->b_mutex);
308 if (!erra)
309 ww_mutex_unlock(&cycle->a_mutex);
310 ww_acquire_fini(&ctx);
311
312 cycle->result = err ?: erra;
313}
314
315static int __test_cycle(unsigned int nthreads)
316{
317 struct test_cycle *cycles;
318 unsigned int n, last = nthreads - 1;
319 int ret;
320
321 cycles = kmalloc_array(nthreads, sizeof(*cycles), GFP_KERNEL);
322 if (!cycles)
323 return -ENOMEM;
324
325 for (n = 0; n < nthreads; n++) {
326 struct test_cycle *cycle = &cycles[n];
327
328 ww_mutex_init(&cycle->a_mutex, &ww_class);
329 if (n == last)
330 cycle->b_mutex = &cycles[0].a_mutex;
331 else
332 cycle->b_mutex = &cycles[n + 1].a_mutex;
333
334 if (n == 0)
335 cycle->a_signal = &cycles[last].b_signal;
336 else
337 cycle->a_signal = &cycles[n - 1].b_signal;
338 init_completion(&cycle->b_signal);
339
340 INIT_WORK(&cycle->work, test_cycle_work);
341 cycle->result = 0;
342 }
343
344 for (n = 0; n < nthreads; n++)
345 queue_work(wq, &cycles[n].work);
346
347 flush_workqueue(wq);
348
349 ret = 0;
350 for (n = 0; n < nthreads; n++) {
351 struct test_cycle *cycle = &cycles[n];
352
353 if (!cycle->result)
354 continue;
355
356 pr_err("cyclic deadlock not resolved, ret[%d/%d] = %d\n",
357 n, nthreads, cycle->result);
358 ret = -EINVAL;
359 break;
360 }
361
362 for (n = 0; n < nthreads; n++)
363 ww_mutex_destroy(&cycles[n].a_mutex);
364 kfree(cycles);
365 return ret;
366}
367
368static int test_cycle(unsigned int ncpus)
369{
370 unsigned int n;
371 int ret;
372
373 for (n = 2; n <= ncpus + 1; n++) {
374 ret = __test_cycle(n);
375 if (ret)
376 return ret;
377 }
378
379 return 0;
380}
381
382struct stress {
383 struct work_struct work;
384 struct ww_mutex *locks;
385 unsigned long timeout;
386 int nlocks;
387};
388
389static int *get_random_order(int count)
390{
391 int *order;
392 int n, r, tmp;
393
394 order = kmalloc_array(count, sizeof(*order), GFP_KERNEL);
395 if (!order)
396 return order;
397
398 for (n = 0; n < count; n++)
399 order[n] = n;
400
401 for (n = count - 1; n > 1; n--) {
402 r = get_random_u32_below(n + 1);
403 if (r != n) {
404 tmp = order[n];
405 order[n] = order[r];
406 order[r] = tmp;
407 }
408 }
409
410 return order;
411}
412
413static void dummy_load(struct stress *stress)
414{
415 usleep_range(1000, 2000);
416}
417
418static void stress_inorder_work(struct work_struct *work)
419{
420 struct stress *stress = container_of(work, typeof(*stress), work);
421 const int nlocks = stress->nlocks;
422 struct ww_mutex *locks = stress->locks;
423 struct ww_acquire_ctx ctx;
424 int *order;
425
426 order = get_random_order(nlocks);
427 if (!order)
428 return;
429
430 do {
431 int contended = -1;
432 int n, err;
433
434 ww_acquire_init(&ctx, &ww_class);
435retry:
436 err = 0;
437 for (n = 0; n < nlocks; n++) {
438 if (n == contended)
439 continue;
440
441 err = ww_mutex_lock(&locks[order[n]], &ctx);
442 if (err < 0)
443 break;
444 }
445 if (!err)
446 dummy_load(stress);
447
448 if (contended > n)
449 ww_mutex_unlock(&locks[order[contended]]);
450 contended = n;
451 while (n--)
452 ww_mutex_unlock(&locks[order[n]]);
453
454 if (err == -EDEADLK) {
455 ww_mutex_lock_slow(&locks[order[contended]], &ctx);
456 goto retry;
457 }
458
459 if (err) {
460 pr_err_once("stress (%s) failed with %d\n",
461 __func__, err);
462 break;
463 }
464
465 ww_acquire_fini(&ctx);
466 } while (!time_after(jiffies, stress->timeout));
467
468 kfree(order);
469 kfree(stress);
470}
471
472struct reorder_lock {
473 struct list_head link;
474 struct ww_mutex *lock;
475};
476
477static void stress_reorder_work(struct work_struct *work)
478{
479 struct stress *stress = container_of(work, typeof(*stress), work);
480 LIST_HEAD(locks);
481 struct ww_acquire_ctx ctx;
482 struct reorder_lock *ll, *ln;
483 int *order;
484 int n, err;
485
486 order = get_random_order(stress->nlocks);
487 if (!order)
488 return;
489
490 for (n = 0; n < stress->nlocks; n++) {
491 ll = kmalloc(sizeof(*ll), GFP_KERNEL);
492 if (!ll)
493 goto out;
494
495 ll->lock = &stress->locks[order[n]];
496 list_add(&ll->link, &locks);
497 }
498 kfree(order);
499 order = NULL;
500
501 do {
502 ww_acquire_init(&ctx, &ww_class);
503
504 list_for_each_entry(ll, &locks, link) {
505 err = ww_mutex_lock(ll->lock, &ctx);
506 if (!err)
507 continue;
508
509 ln = ll;
510 list_for_each_entry_continue_reverse(ln, &locks, link)
511 ww_mutex_unlock(ln->lock);
512
513 if (err != -EDEADLK) {
514 pr_err_once("stress (%s) failed with %d\n",
515 __func__, err);
516 break;
517 }
518
519 ww_mutex_lock_slow(ll->lock, &ctx);
520 list_move(&ll->link, &locks); /* restarts iteration */
521 }
522
523 dummy_load(stress);
524 list_for_each_entry(ll, &locks, link)
525 ww_mutex_unlock(ll->lock);
526
527 ww_acquire_fini(&ctx);
528 } while (!time_after(jiffies, stress->timeout));
529
530out:
531 list_for_each_entry_safe(ll, ln, &locks, link)
532 kfree(ll);
533 kfree(order);
534 kfree(stress);
535}
536
537static void stress_one_work(struct work_struct *work)
538{
539 struct stress *stress = container_of(work, typeof(*stress), work);
540 const int nlocks = stress->nlocks;
541 struct ww_mutex *lock = stress->locks + get_random_u32_below(nlocks);
542 int err;
543
544 do {
545 err = ww_mutex_lock(lock, NULL);
546 if (!err) {
547 dummy_load(stress);
548 ww_mutex_unlock(lock);
549 } else {
550 pr_err_once("stress (%s) failed with %d\n",
551 __func__, err);
552 break;
553 }
554 } while (!time_after(jiffies, stress->timeout));
555
556 kfree(stress);
557}
558
559#define STRESS_INORDER BIT(0)
560#define STRESS_REORDER BIT(1)
561#define STRESS_ONE BIT(2)
562#define STRESS_ALL (STRESS_INORDER | STRESS_REORDER | STRESS_ONE)
563
564static int stress(int nlocks, int nthreads, unsigned int flags)
565{
566 struct ww_mutex *locks;
567 int n;
568
569 locks = kmalloc_array(nlocks, sizeof(*locks), GFP_KERNEL);
570 if (!locks)
571 return -ENOMEM;
572
573 for (n = 0; n < nlocks; n++)
574 ww_mutex_init(&locks[n], &ww_class);
575
576 for (n = 0; nthreads; n++) {
577 struct stress *stress;
578 void (*fn)(struct work_struct *work);
579
580 fn = NULL;
581 switch (n & 3) {
582 case 0:
583 if (flags & STRESS_INORDER)
584 fn = stress_inorder_work;
585 break;
586 case 1:
587 if (flags & STRESS_REORDER)
588 fn = stress_reorder_work;
589 break;
590 case 2:
591 if (flags & STRESS_ONE)
592 fn = stress_one_work;
593 break;
594 }
595
596 if (!fn)
597 continue;
598
599 stress = kmalloc(sizeof(*stress), GFP_KERNEL);
600 if (!stress)
601 break;
602
603 INIT_WORK(&stress->work, fn);
604 stress->locks = locks;
605 stress->nlocks = nlocks;
606 stress->timeout = jiffies + 2*HZ;
607
608 queue_work(wq, &stress->work);
609 nthreads--;
610 }
611
612 flush_workqueue(wq);
613
614 for (n = 0; n < nlocks; n++)
615 ww_mutex_destroy(&locks[n]);
616 kfree(locks);
617
618 return 0;
619}
620
621static int __init test_ww_mutex_init(void)
622{
623 int ncpus = num_online_cpus();
624 int ret, i;
625
626 printk(KERN_INFO "Beginning ww mutex selftests\n");
627
628 wq = alloc_workqueue("test-ww_mutex", WQ_UNBOUND, 0);
629 if (!wq)
630 return -ENOMEM;
631
632 ret = test_mutex();
633 if (ret)
634 return ret;
635
636 ret = test_aa(false);
637 if (ret)
638 return ret;
639
640 ret = test_aa(true);
641 if (ret)
642 return ret;
643
644 for (i = 0; i < 4; i++) {
645 ret = test_abba(i & 1, i & 2);
646 if (ret)
647 return ret;
648 }
649
650 ret = test_cycle(ncpus);
651 if (ret)
652 return ret;
653
654 ret = stress(16, 2*ncpus, STRESS_INORDER);
655 if (ret)
656 return ret;
657
658 ret = stress(16, 2*ncpus, STRESS_REORDER);
659 if (ret)
660 return ret;
661
662 ret = stress(4095, hweight32(STRESS_ALL)*ncpus, STRESS_ALL);
663 if (ret)
664 return ret;
665
666 printk(KERN_INFO "All ww mutex selftests passed\n");
667 return 0;
668}
669
670static void __exit test_ww_mutex_exit(void)
671{
672 destroy_workqueue(wq);
673}
674
675module_init(test_ww_mutex_init);
676module_exit(test_ww_mutex_exit);
677
678MODULE_LICENSE("GPL");
679MODULE_AUTHOR("Intel Corporation");