drivers/dma-buf/st-dma-fence-chain.c

   1 // SPDX-License-Identifier: MIT
   2
   3 /*
   4  * Copyright © 2019 Intel Corporation
   5  */
   6
   7 #include <linux/delay.h>
   8 #include <linux/dma-fence.h>
   9 #include <linux/dma-fence-chain.h>
  10 #include <linux/kernel.h>
  11 #include <linux/kthread.h>
  12 #include <linux/mm.h>
  13 #include <linux/sched/signal.h>
  14 #include <linux/slab.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/random.h>
  17
  18 #include "selftest.h"
  19
  20 #define CHAIN_SZ (4 << 10)
  21
  22 static struct kmem_cache *slab_fences;
  23
  24 static inline struct mock_fence {
  25         struct dma_fence base;
  26         spinlock_t lock;
  27 } *to_mock_fence(struct dma_fence *f) {
  28         return container_of(f, struct mock_fence, base);
  29 }
  30
  31 static const char *mock_name(struct dma_fence *f)
  32 {
  33         return "mock";
  34 }
  35
  36 static void mock_fence_release(struct dma_fence *f)
  37 {
  38         kmem_cache_free(slab_fences, to_mock_fence(f));
  39 }
  40
  41 static const struct dma_fence_ops mock_ops = {
  42         .get_driver_name = mock_name,
  43         .get_timeline_name = mock_name,
  44         .release = mock_fence_release,
  45 };
  46
  47 static struct dma_fence *mock_fence(void)
  48 {
  49         struct mock_fence *f;
  50
  51         f = kmem_cache_alloc(slab_fences, GFP_KERNEL);
  52         if (!f)
  53                 return NULL;
  54
  55         spin_lock_init(&f->lock);
  56         dma_fence_init(&f->base, &mock_ops, &f->lock, 0, 0);
  57
  58         return &f->base;
  59 }
  60
  61 static inline struct mock_chain {
  62         struct dma_fence_chain base;
  63 } *to_mock_chain(struct dma_fence *f) {
  64         return container_of(f, struct mock_chain, base.base);
  65 }
  66
  67 static struct dma_fence *mock_chain(struct dma_fence *prev,
  68                                     struct dma_fence *fence,
  69                                     u64 seqno)
  70 {
  71         struct mock_chain *f;
  72
  73         f = kmalloc(sizeof(*f), GFP_KERNEL);
  74         if (!f)
  75                 return NULL;
  76
  77         dma_fence_chain_init(&f->base,
  78                              dma_fence_get(prev),
  79                              dma_fence_get(fence),
  80                              seqno);
  81
  82         return &f->base.base;
  83 }
  84
  85 static int sanitycheck(void *arg)
  86 {
  87         struct dma_fence *f, *chain;
  88         int err = 0;
  89
  90         f = mock_fence();
  91         if (!f)
  92                 return -ENOMEM;
  93
  94         chain = mock_chain(NULL, f, 1);
  95         if (!chain)
  96                 err = -ENOMEM;
  97
  98         dma_fence_signal(f);
  99         dma_fence_put(f);
 100
 101         dma_fence_put(chain);
 102
 103         return err;
 104 }
 105
 106 struct fence_chains {
 107         unsigned int chain_length;
 108         struct dma_fence **fences;
 109         struct dma_fence **chains;
 110
 111         struct dma_fence *tail;
 112 };
 113
 114 static uint64_t seqno_inc(unsigned int i)
 115 {
 116         return i + 1;
 117 }
 118
 119 static int fence_chains_init(struct fence_chains *fc, unsigned int count,
 120                              uint64_t (*seqno_fn)(unsigned int))
 121 {
 122         unsigned int i;
 123         int err = 0;
 124
 125         fc->chains = kvmalloc_array(count, sizeof(*fc->chains),
 126                                     GFP_KERNEL | __GFP_ZERO);
 127         if (!fc->chains)
 128                 return -ENOMEM;
 129
 130         fc->fences = kvmalloc_array(count, sizeof(*fc->fences),
 131                                     GFP_KERNEL | __GFP_ZERO);
 132         if (!fc->fences) {
 133                 err = -ENOMEM;
 134                 goto err_chains;
 135         }
 136
 137         fc->tail = NULL;
 138         for (i = 0; i < count; i++) {
 139                 fc->fences[i] = mock_fence();
 140                 if (!fc->fences[i]) {
 141                         err = -ENOMEM;
 142                         goto unwind;
 143                 }
 144
 145                 fc->chains[i] = mock_chain(fc->tail,
 146                                            fc->fences[i],
 147                                            seqno_fn(i));
 148                 if (!fc->chains[i]) {
 149                         err = -ENOMEM;
 150                         goto unwind;
 151                 }
 152
 153                 fc->tail = fc->chains[i];
 154         }
 155
 156         fc->chain_length = i;
 157         return 0;
 158
 159 unwind:
 160         for (i = 0; i < count; i++) {
 161                 dma_fence_put(fc->fences[i]);
 162                 dma_fence_put(fc->chains[i]);
 163         }
 164         kvfree(fc->fences);
 165 err_chains:
 166         kvfree(fc->chains);
 167         return err;
 168 }
 169
 170 static void fence_chains_fini(struct fence_chains *fc)
 171 {
 172         unsigned int i;
 173
 174         for (i = 0; i < fc->chain_length; i++) {
 175                 dma_fence_signal(fc->fences[i]);
 176                 dma_fence_put(fc->fences[i]);
 177         }
 178         kvfree(fc->fences);
 179
 180         for (i = 0; i < fc->chain_length; i++)
 181                 dma_fence_put(fc->chains[i]);
 182         kvfree(fc->chains);
 183 }
 184
 185 static int find_seqno(void *arg)
 186 {
 187         struct fence_chains fc;
 188         struct dma_fence *fence;
 189         int err;
 190         int i;
 191
 192         err = fence_chains_init(&fc, 64, seqno_inc);
 193         if (err)
 194                 return err;
 195
 196         fence = dma_fence_get(fc.tail);
 197         err = dma_fence_chain_find_seqno(&fence, 0);
 198         dma_fence_put(fence);
 199         if (err) {
 200                 pr_err("Reported %d for find_seqno(0)!\n", err);
 201                 goto err;
 202         }
 203
 204         for (i = 0; i < fc.chain_length; i++) {
 205                 fence = dma_fence_get(fc.tail);
 206                 err = dma_fence_chain_find_seqno(&fence, i + 1);
 207                 dma_fence_put(fence);
 208                 if (err) {
 209                         pr_err("Reported %d for find_seqno(%d:%d)!\n",
 210                                err, fc.chain_length + 1, i + 1);
 211                         goto err;
 212                 }
 213                 if (fence != fc.chains[i]) {
 214                         pr_err("Incorrect fence reported by find_seqno(%d:%d)\n",
 215                                fc.chain_length + 1, i + 1);
 216                         err = -EINVAL;
 217                         goto err;
 218                 }
 219
 220                 dma_fence_get(fence);
 221                 err = dma_fence_chain_find_seqno(&fence, i + 1);
 222                 dma_fence_put(fence);
 223                 if (err) {
 224                         pr_err("Error reported for finding self\n");
 225                         goto err;
 226                 }
 227                 if (fence != fc.chains[i]) {
 228                         pr_err("Incorrect fence reported by find self\n");
 229                         err = -EINVAL;
 230                         goto err;
 231                 }
 232
 233                 dma_fence_get(fence);
 234                 err = dma_fence_chain_find_seqno(&fence, i + 2);
 235                 dma_fence_put(fence);
 236                 if (!err) {
 237                         pr_err("Error not reported for future fence: find_seqno(%d:%d)!\n",
 238                                i + 1, i + 2);
 239                         err = -EINVAL;
 240                         goto err;
 241                 }
 242
 243                 dma_fence_get(fence);
 244                 err = dma_fence_chain_find_seqno(&fence, i);
 245                 dma_fence_put(fence);
 246                 if (err) {
 247                         pr_err("Error reported for previous fence!\n");
 248                         goto err;
 249                 }
 250                 if (i > 0 && fence != fc.chains[i - 1]) {
 251                         pr_err("Incorrect fence reported by find_seqno(%d:%d)\n",
 252                                i + 1, i);
 253                         err = -EINVAL;
 254                         goto err;
 255                 }
 256         }
 257
 258 err:
 259         fence_chains_fini(&fc);
 260         return err;
 261 }
 262
 263 static int find_signaled(void *arg)
 264 {
 265         struct fence_chains fc;
 266         struct dma_fence *fence;
 267         int err;
 268
 269         err = fence_chains_init(&fc, 2, seqno_inc);
 270         if (err)
 271                 return err;
 272
 273         dma_fence_signal(fc.fences[0]);
 274
 275         fence = dma_fence_get(fc.tail);
 276         err = dma_fence_chain_find_seqno(&fence, 1);
 277         dma_fence_put(fence);
 278         if (err) {
 279                 pr_err("Reported %d for find_seqno()!\n", err);
 280                 goto err;
 281         }
 282
 283         if (fence && fence != fc.chains[0]) {
 284                 pr_err("Incorrect chain-fence.seqno:%lld reported for completed seqno:1\n",
 285                        fence->seqno);
 286
 287                 dma_fence_get(fence);
 288                 err = dma_fence_chain_find_seqno(&fence, 1);
 289                 dma_fence_put(fence);
 290                 if (err)
 291                         pr_err("Reported %d for finding self!\n", err);
 292
 293                 err = -EINVAL;
 294         }
 295
 296 err:
 297         fence_chains_fini(&fc);
 298         return err;
 299 }
 300
 301 static int find_out_of_order(void *arg)
 302 {
 303         struct fence_chains fc;
 304         struct dma_fence *fence;
 305         int err;
 306
 307         err = fence_chains_init(&fc, 3, seqno_inc);
 308         if (err)
 309                 return err;
 310
 311         dma_fence_signal(fc.fences[1]);
 312
 313         fence = dma_fence_get(fc.tail);
 314         err = dma_fence_chain_find_seqno(&fence, 2);
 315         dma_fence_put(fence);
 316         if (err) {
 317                 pr_err("Reported %d for find_seqno()!\n", err);
 318                 goto err;
 319         }
 320
 321         /*
 322          * We signaled the middle fence (2) of the 1-2-3 chain. The behavior
 323          * of the dma-fence-chain is to make us wait for all the fences up to
 324          * the point we want. Since fence 1 is still not signaled, this what
 325          * we should get as fence to wait upon (fence 2 being garbage
 326          * collected during the traversal of the chain).
 327          */
 328         if (fence != fc.chains[0]) {
 329                 pr_err("Incorrect chain-fence.seqno:%lld reported for completed seqno:2\n",
 330                        fence ? fence->seqno : 0);
 331
 332                 err = -EINVAL;
 333         }
 334
 335 err:
 336         fence_chains_fini(&fc);
 337         return err;
 338 }
 339
 340 static uint64_t seqno_inc2(unsigned int i)
 341 {
 342         return 2 * i + 2;
 343 }
 344
 345 static int find_gap(void *arg)
 346 {
 347         struct fence_chains fc;
 348         struct dma_fence *fence;
 349         int err;
 350         int i;
 351
 352         err = fence_chains_init(&fc, 64, seqno_inc2);
 353         if (err)
 354                 return err;
 355
 356         for (i = 0; i < fc.chain_length; i++) {
 357                 fence = dma_fence_get(fc.tail);
 358                 err = dma_fence_chain_find_seqno(&fence, 2 * i + 1);
 359                 dma_fence_put(fence);
 360                 if (err) {
 361                         pr_err("Reported %d for find_seqno(%d:%d)!\n",
 362                                err, fc.chain_length + 1, 2 * i + 1);
 363                         goto err;
 364                 }
 365                 if (fence != fc.chains[i]) {
 366                         pr_err("Incorrect fence.seqno:%lld reported by find_seqno(%d:%d)\n",
 367                                fence->seqno,
 368                                fc.chain_length + 1,
 369                                2 * i + 1);
 370                         err = -EINVAL;
 371                         goto err;
 372                 }
 373
 374                 dma_fence_get(fence);
 375                 err = dma_fence_chain_find_seqno(&fence, 2 * i + 2);
 376                 dma_fence_put(fence);
 377                 if (err) {
 378                         pr_err("Error reported for finding self\n");
 379                         goto err;
 380                 }
 381                 if (fence != fc.chains[i]) {
 382                         pr_err("Incorrect fence reported by find self\n");
 383                         err = -EINVAL;
 384                         goto err;
 385                 }
 386         }
 387
 388 err:
 389         fence_chains_fini(&fc);
 390         return err;
 391 }
 392
 393 struct find_race {
 394         struct fence_chains fc;
 395         atomic_t children;
 396 };
 397
 398 static int __find_race(void *arg)
 399 {
 400         struct find_race *data = arg;
 401         int err = 0;
 402
 403         while (!kthread_should_stop()) {
 404                 struct dma_fence *fence = dma_fence_get(data->fc.tail);
 405                 int seqno;
 406
 407                 seqno = prandom_u32_max(data->fc.chain_length) + 1;
 408
 409                 err = dma_fence_chain_find_seqno(&fence, seqno);
 410                 if (err) {
 411                         pr_err("Failed to find fence seqno:%d\n",
 412                                seqno);
 413                         dma_fence_put(fence);
 414                         break;
 415                 }
 416                 if (!fence)
 417                         goto signal;
 418
 419                 /*
 420                  * We can only find ourselves if we are on fence we were
 421                  * looking for.
 422                  */
 423                 if (fence->seqno == seqno) {
 424                         err = dma_fence_chain_find_seqno(&fence, seqno);
 425                         if (err) {
 426                                 pr_err("Reported an invalid fence for find-self:%d\n",
 427                                        seqno);
 428                                 dma_fence_put(fence);
 429                                 break;
 430                         }
 431                 }
 432
 433                 dma_fence_put(fence);
 434
 435 signal:
 436                 seqno = prandom_u32_max(data->fc.chain_length - 1);
 437                 dma_fence_signal(data->fc.fences[seqno]);
 438                 cond_resched();
 439         }
 440
 441         if (atomic_dec_and_test(&data->children))
 442                 wake_up_var(&data->children);
 443         return err;
 444 }
 445
 446 static int find_race(void *arg)
 447 {
 448         struct find_race data;
 449         int ncpus = num_online_cpus();
 450         struct task_struct **threads;
 451         unsigned long count;
 452         int err;
 453         int i;
 454
 455         err = fence_chains_init(&data.fc, CHAIN_SZ, seqno_inc);
 456         if (err)
 457                 return err;
 458
 459         threads = kmalloc_array(ncpus, sizeof(*threads), GFP_KERNEL);
 460         if (!threads) {
 461                 err = -ENOMEM;
 462                 goto err;
 463         }
 464
 465         atomic_set(&data.children, 0);
 466         for (i = 0; i < ncpus; i++) {
 467                 threads[i] = kthread_run(__find_race, &data, "dmabuf/%d", i);
 468                 if (IS_ERR(threads[i])) {
 469                         ncpus = i;
 470                         break;
 471                 }
 472                 atomic_inc(&data.children);
 473                 get_task_struct(threads[i]);
 474         }
 475
 476         wait_var_event_timeout(&data.children,
 477                                !atomic_read(&data.children),
 478                                5 * HZ);
 479
 480         for (i = 0; i < ncpus; i++) {
 481                 int ret;
 482
 483                 ret = kthread_stop(threads[i]);
 484                 if (ret && !err)
 485                         err = ret;
 486                 put_task_struct(threads[i]);
 487         }
 488         kfree(threads);
 489
 490         count = 0;
 491         for (i = 0; i < data.fc.chain_length; i++)
 492                 if (dma_fence_is_signaled(data.fc.fences[i]))
 493                         count++;
 494         pr_info("Completed %lu cycles\n", count);
 495
 496 err:
 497         fence_chains_fini(&data.fc);
 498         return err;
 499 }
 500
 501 static int signal_forward(void *arg)
 502 {
 503         struct fence_chains fc;
 504         int err;
 505         int i;
 506
 507         err = fence_chains_init(&fc, 64, seqno_inc);
 508         if (err)
 509                 return err;
 510
 511         for (i = 0; i < fc.chain_length; i++) {
 512                 dma_fence_signal(fc.fences[i]);
 513
 514                 if (!dma_fence_is_signaled(fc.chains[i])) {
 515                         pr_err("chain[%d] not signaled!\n", i);
 516                         err = -EINVAL;
 517                         goto err;
 518                 }
 519
 520                 if (i + 1 < fc.chain_length &&
 521                     dma_fence_is_signaled(fc.chains[i + 1])) {
 522                         pr_err("chain[%d] is signaled!\n", i);
 523                         err = -EINVAL;
 524                         goto err;
 525                 }
 526         }
 527
 528 err:
 529         fence_chains_fini(&fc);
 530         return err;
 531 }
 532
 533 static int signal_backward(void *arg)
 534 {
 535         struct fence_chains fc;
 536         int err;
 537         int i;
 538
 539         err = fence_chains_init(&fc, 64, seqno_inc);
 540         if (err)
 541                 return err;
 542
 543         for (i = fc.chain_length; i--; ) {
 544                 dma_fence_signal(fc.fences[i]);
 545
 546                 if (i > 0 && dma_fence_is_signaled(fc.chains[i])) {
 547                         pr_err("chain[%d] is signaled!\n", i);
 548                         err = -EINVAL;
 549                         goto err;
 550                 }
 551         }
 552
 553         for (i = 0; i < fc.chain_length; i++) {
 554                 if (!dma_fence_is_signaled(fc.chains[i])) {
 555                         pr_err("chain[%d] was not signaled!\n", i);
 556                         err = -EINVAL;
 557                         goto err;
 558                 }
 559         }
 560
 561 err:
 562         fence_chains_fini(&fc);
 563         return err;
 564 }
 565
 566 static int __wait_fence_chains(void *arg)
 567 {
 568         struct fence_chains *fc = arg;
 569
 570         if (dma_fence_wait(fc->tail, false))
 571                 return -EIO;
 572
 573         return 0;
 574 }
 575
 576 static int wait_forward(void *arg)
 577 {
 578         struct fence_chains fc;
 579         struct task_struct *tsk;
 580         int err;
 581         int i;
 582
 583         err = fence_chains_init(&fc, CHAIN_SZ, seqno_inc);
 584         if (err)
 585                 return err;
 586
 587         tsk = kthread_run(__wait_fence_chains, &fc, "dmabuf/wait");
 588         if (IS_ERR(tsk)) {
 589                 err = PTR_ERR(tsk);
 590                 goto err;
 591         }
 592         get_task_struct(tsk);
 593         yield_to(tsk, true);
 594
 595         for (i = 0; i < fc.chain_length; i++)
 596                 dma_fence_signal(fc.fences[i]);
 597
 598         err = kthread_stop(tsk);
 599         put_task_struct(tsk);
 600
 601 err:
 602         fence_chains_fini(&fc);
 603         return err;
 604 }
 605
 606 static int wait_backward(void *arg)
 607 {
 608         struct fence_chains fc;
 609         struct task_struct *tsk;
 610         int err;
 611         int i;
 612
 613         err = fence_chains_init(&fc, CHAIN_SZ, seqno_inc);
 614         if (err)
 615                 return err;
 616
 617         tsk = kthread_run(__wait_fence_chains, &fc, "dmabuf/wait");
 618         if (IS_ERR(tsk)) {
 619                 err = PTR_ERR(tsk);
 620                 goto err;
 621         }
 622         get_task_struct(tsk);
 623         yield_to(tsk, true);
 624
 625         for (i = fc.chain_length; i--; )
 626                 dma_fence_signal(fc.fences[i]);
 627
 628         err = kthread_stop(tsk);
 629         put_task_struct(tsk);
 630
 631 err:
 632         fence_chains_fini(&fc);
 633         return err;
 634 }
 635
 636 static void randomise_fences(struct fence_chains *fc)
 637 {
 638         unsigned int count = fc->chain_length;
 639
 640         /* Fisher-Yates shuffle courtesy of Knuth */
 641         while (--count) {
 642                 unsigned int swp;
 643
 644                 swp = prandom_u32_max(count + 1);
 645                 if (swp == count)
 646                         continue;
 647
 648                 swap(fc->fences[count], fc->fences[swp]);
 649         }
 650 }
 651
 652 static int wait_random(void *arg)
 653 {
 654         struct fence_chains fc;
 655         struct task_struct *tsk;
 656         int err;
 657         int i;
 658
 659         err = fence_chains_init(&fc, CHAIN_SZ, seqno_inc);
 660         if (err)
 661                 return err;
 662
 663         randomise_fences(&fc);
 664
 665         tsk = kthread_run(__wait_fence_chains, &fc, "dmabuf/wait");
 666         if (IS_ERR(tsk)) {
 667                 err = PTR_ERR(tsk);
 668                 goto err;
 669         }
 670         get_task_struct(tsk);
 671         yield_to(tsk, true);
 672
 673         for (i = 0; i < fc.chain_length; i++)
 674                 dma_fence_signal(fc.fences[i]);
 675
 676         err = kthread_stop(tsk);
 677         put_task_struct(tsk);
 678
 679 err:
 680         fence_chains_fini(&fc);
 681         return err;
 682 }
 683
 684 int dma_fence_chain(void)
 685 {
 686         static const struct subtest tests[] = {
 687                 SUBTEST(sanitycheck),
 688                 SUBTEST(find_seqno),
 689                 SUBTEST(find_signaled),
 690                 SUBTEST(find_out_of_order),
 691                 SUBTEST(find_gap),
 692                 SUBTEST(find_race),
 693                 SUBTEST(signal_forward),
 694                 SUBTEST(signal_backward),
 695                 SUBTEST(wait_forward),
 696                 SUBTEST(wait_backward),
 697                 SUBTEST(wait_random),
 698         };
 699         int ret;
 700
 701         pr_info("sizeof(dma_fence_chain)=%zu\n",
 702                 sizeof(struct dma_fence_chain));
 703
 704         slab_fences = KMEM_CACHE(mock_fence,
 705                                  SLAB_TYPESAFE_BY_RCU |
 706                                  SLAB_HWCACHE_ALIGN);
 707         if (!slab_fences)
 708                 return -ENOMEM;
 709
 710         ret = subtests(tests, NULL);
 711
 712         kmem_cache_destroy(slab_fences);
 713         return ret;
 714 }