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