1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2018, Matthew Macy <mmacy@freebsd.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/types.h> 34 #include <sys/systm.h> 35 #include <sys/counter.h> 36 #include <sys/epoch.h> 37 #include <sys/gtaskqueue.h> 38 #include <sys/kernel.h> 39 #include <sys/limits.h> 40 #include <sys/lock.h> 41 #include <sys/malloc.h> 42 #include <sys/mutex.h> 43 #include <sys/pcpu.h> 44 #include <sys/proc.h> 45 #include <sys/sched.h> 46 #include <sys/sx.h> 47 #include <sys/smp.h> 48 #include <sys/sysctl.h> 49 #include <sys/turnstile.h> 50 #include <vm/vm.h> 51 #include <vm/vm_extern.h> 52 #include <vm/vm_kern.h> 53 #include <vm/uma.h> 54 55 #include <ck_epoch.h> 56 57 static MALLOC_DEFINE(M_EPOCH, "epoch", "epoch based reclamation"); 58 59 #ifdef __amd64__ 60 #define EPOCH_ALIGN CACHE_LINE_SIZE*2 61 #else 62 #define EPOCH_ALIGN CACHE_LINE_SIZE 63 #endif 64 65 TAILQ_HEAD (epoch_tdlist, epoch_tracker); 66 typedef struct epoch_record { 67 ck_epoch_record_t er_record; 68 struct epoch_context er_drain_ctx; 69 struct epoch *er_parent; 70 volatile struct epoch_tdlist er_tdlist; 71 volatile uint32_t er_gen; 72 uint32_t er_cpuid; 73 } __aligned(EPOCH_ALIGN) *epoch_record_t; 74 75 struct epoch { 76 struct ck_epoch e_epoch __aligned(EPOCH_ALIGN); 77 epoch_record_t e_pcpu_record; 78 int e_idx; 79 int e_flags; 80 struct sx e_drain_sx; 81 struct mtx e_drain_mtx; 82 volatile int e_drain_count; 83 }; 84 85 /* arbitrary --- needs benchmarking */ 86 #define MAX_ADAPTIVE_SPIN 100 87 #define MAX_EPOCHS 64 88 89 CTASSERT(sizeof(ck_epoch_entry_t) == sizeof(struct epoch_context)); 90 SYSCTL_NODE(_kern, OID_AUTO, epoch, CTLFLAG_RW, 0, "epoch information"); 91 SYSCTL_NODE(_kern_epoch, OID_AUTO, stats, CTLFLAG_RW, 0, "epoch stats"); 92 93 /* Stats. */ 94 static counter_u64_t block_count; 95 96 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, nblocked, CTLFLAG_RW, 97 &block_count, "# of times a thread was in an epoch when epoch_wait was called"); 98 static counter_u64_t migrate_count; 99 100 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, migrations, CTLFLAG_RW, 101 &migrate_count, "# of times thread was migrated to another CPU in epoch_wait"); 102 static counter_u64_t turnstile_count; 103 104 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, ncontended, CTLFLAG_RW, 105 &turnstile_count, "# of times a thread was blocked on a lock in an epoch during an epoch_wait"); 106 static counter_u64_t switch_count; 107 108 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, switches, CTLFLAG_RW, 109 &switch_count, "# of times a thread voluntarily context switched in epoch_wait"); 110 static counter_u64_t epoch_call_count; 111 112 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, epoch_calls, CTLFLAG_RW, 113 &epoch_call_count, "# of times a callback was deferred"); 114 static counter_u64_t epoch_call_task_count; 115 116 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, epoch_call_tasks, CTLFLAG_RW, 117 &epoch_call_task_count, "# of times a callback task was run"); 118 119 TAILQ_HEAD (threadlist, thread); 120 121 CK_STACK_CONTAINER(struct ck_epoch_entry, stack_entry, 122 ck_epoch_entry_container) 123 124 epoch_t allepochs[MAX_EPOCHS]; 125 126 DPCPU_DEFINE(struct grouptask, epoch_cb_task); 127 DPCPU_DEFINE(int, epoch_cb_count); 128 129 static __read_mostly int inited; 130 static __read_mostly int epoch_count; 131 __read_mostly epoch_t global_epoch; 132 __read_mostly epoch_t global_epoch_preempt; 133 134 static void epoch_call_task(void *context __unused); 135 static uma_zone_t pcpu_zone_record; 136 137 static void 138 epoch_init(void *arg __unused) 139 { 140 int cpu; 141 142 block_count = counter_u64_alloc(M_WAITOK); 143 migrate_count = counter_u64_alloc(M_WAITOK); 144 turnstile_count = counter_u64_alloc(M_WAITOK); 145 switch_count = counter_u64_alloc(M_WAITOK); 146 epoch_call_count = counter_u64_alloc(M_WAITOK); 147 epoch_call_task_count = counter_u64_alloc(M_WAITOK); 148 149 pcpu_zone_record = uma_zcreate("epoch_record pcpu", 150 sizeof(struct epoch_record), NULL, NULL, NULL, NULL, 151 UMA_ALIGN_PTR, UMA_ZONE_PCPU); 152 CPU_FOREACH(cpu) { 153 GROUPTASK_INIT(DPCPU_ID_PTR(cpu, epoch_cb_task), 0, 154 epoch_call_task, NULL); 155 taskqgroup_attach_cpu(qgroup_softirq, 156 DPCPU_ID_PTR(cpu, epoch_cb_task), NULL, cpu, NULL, NULL, 157 "epoch call task"); 158 } 159 inited = 1; 160 global_epoch = epoch_alloc(0); 161 global_epoch_preempt = epoch_alloc(EPOCH_PREEMPT); 162 } 163 SYSINIT(epoch, SI_SUB_TASKQ + 1, SI_ORDER_FIRST, epoch_init, NULL); 164 165 #if !defined(EARLY_AP_STARTUP) 166 static void 167 epoch_init_smp(void *dummy __unused) 168 { 169 inited = 2; 170 } 171 SYSINIT(epoch_smp, SI_SUB_SMP + 1, SI_ORDER_FIRST, epoch_init_smp, NULL); 172 #endif 173 174 static void 175 epoch_ctor(epoch_t epoch) 176 { 177 epoch_record_t er; 178 int cpu; 179 180 epoch->e_pcpu_record = uma_zalloc_pcpu(pcpu_zone_record, M_WAITOK); 181 CPU_FOREACH(cpu) { 182 er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu); 183 bzero(er, sizeof(*er)); 184 ck_epoch_register(&epoch->e_epoch, &er->er_record, NULL); 185 TAILQ_INIT((struct threadlist *)(uintptr_t)&er->er_tdlist); 186 er->er_cpuid = cpu; 187 er->er_parent = epoch; 188 } 189 } 190 191 static void 192 epoch_adjust_prio(struct thread *td, u_char prio) 193 { 194 195 thread_lock(td); 196 sched_prio(td, prio); 197 thread_unlock(td); 198 } 199 200 epoch_t 201 epoch_alloc(int flags) 202 { 203 epoch_t epoch; 204 205 if (__predict_false(!inited)) 206 panic("%s called too early in boot", __func__); 207 epoch = malloc(sizeof(struct epoch), M_EPOCH, M_ZERO | M_WAITOK); 208 ck_epoch_init(&epoch->e_epoch); 209 epoch_ctor(epoch); 210 MPASS(epoch_count < MAX_EPOCHS - 2); 211 epoch->e_flags = flags; 212 epoch->e_idx = epoch_count; 213 sx_init(&epoch->e_drain_sx, "epoch-drain-sx"); 214 mtx_init(&epoch->e_drain_mtx, "epoch-drain-mtx", NULL, MTX_DEF); 215 allepochs[epoch_count++] = epoch; 216 return (epoch); 217 } 218 219 void 220 epoch_free(epoch_t epoch) 221 { 222 223 epoch_drain_callbacks(epoch); 224 allepochs[epoch->e_idx] = NULL; 225 epoch_wait(global_epoch); 226 uma_zfree_pcpu(pcpu_zone_record, epoch->e_pcpu_record); 227 mtx_destroy(&epoch->e_drain_mtx); 228 sx_destroy(&epoch->e_drain_sx); 229 free(epoch, M_EPOCH); 230 } 231 232 static epoch_record_t 233 epoch_currecord(epoch_t epoch) 234 { 235 236 return (zpcpu_get_cpu(epoch->e_pcpu_record, curcpu)); 237 } 238 239 #define INIT_CHECK(epoch) \ 240 do { \ 241 if (__predict_false((epoch) == NULL)) \ 242 return; \ 243 } while (0) 244 245 void 246 epoch_enter_preempt(epoch_t epoch, epoch_tracker_t et) 247 { 248 struct epoch_record *er; 249 struct thread *td; 250 251 MPASS(cold || epoch != NULL); 252 INIT_CHECK(epoch); 253 MPASS(epoch->e_flags & EPOCH_PREEMPT); 254 #ifdef EPOCH_TRACKER_DEBUG 255 et->et_magic_pre = EPOCH_MAGIC0; 256 et->et_magic_post = EPOCH_MAGIC1; 257 #endif 258 td = curthread; 259 et->et_td = td; 260 td->td_epochnest++; 261 critical_enter(); 262 sched_pin(); 263 264 td->td_pre_epoch_prio = td->td_priority; 265 er = epoch_currecord(epoch); 266 TAILQ_INSERT_TAIL(&er->er_tdlist, et, et_link); 267 ck_epoch_begin(&er->er_record, &et->et_section); 268 critical_exit(); 269 } 270 271 void 272 epoch_enter(epoch_t epoch) 273 { 274 struct thread *td; 275 epoch_record_t er; 276 277 MPASS(cold || epoch != NULL); 278 INIT_CHECK(epoch); 279 td = curthread; 280 281 td->td_epochnest++; 282 critical_enter(); 283 er = epoch_currecord(epoch); 284 ck_epoch_begin(&er->er_record, NULL); 285 } 286 287 void 288 epoch_exit_preempt(epoch_t epoch, epoch_tracker_t et) 289 { 290 struct epoch_record *er; 291 struct thread *td; 292 293 INIT_CHECK(epoch); 294 td = curthread; 295 critical_enter(); 296 sched_unpin(); 297 MPASS(td->td_epochnest); 298 td->td_epochnest--; 299 er = epoch_currecord(epoch); 300 MPASS(epoch->e_flags & EPOCH_PREEMPT); 301 MPASS(et != NULL); 302 MPASS(et->et_td == td); 303 #ifdef EPOCH_TRACKER_DEBUG 304 MPASS(et->et_magic_pre == EPOCH_MAGIC0); 305 MPASS(et->et_magic_post == EPOCH_MAGIC1); 306 et->et_magic_pre = 0; 307 et->et_magic_post = 0; 308 #endif 309 #ifdef INVARIANTS 310 et->et_td = (void*)0xDEADBEEF; 311 #endif 312 ck_epoch_end(&er->er_record, &et->et_section); 313 TAILQ_REMOVE(&er->er_tdlist, et, et_link); 314 er->er_gen++; 315 if (__predict_false(td->td_pre_epoch_prio != td->td_priority)) 316 epoch_adjust_prio(td, td->td_pre_epoch_prio); 317 critical_exit(); 318 } 319 320 void 321 epoch_exit(epoch_t epoch) 322 { 323 struct thread *td; 324 epoch_record_t er; 325 326 INIT_CHECK(epoch); 327 td = curthread; 328 MPASS(td->td_epochnest); 329 td->td_epochnest--; 330 er = epoch_currecord(epoch); 331 ck_epoch_end(&er->er_record, NULL); 332 critical_exit(); 333 } 334 335 /* 336 * epoch_block_handler_preempt() is a callback from the CK code when another 337 * thread is currently in an epoch section. 338 */ 339 static void 340 epoch_block_handler_preempt(struct ck_epoch *global __unused, 341 ck_epoch_record_t *cr, void *arg __unused) 342 { 343 epoch_record_t record; 344 struct thread *td, *owner, *curwaittd; 345 struct epoch_tracker *tdwait; 346 struct turnstile *ts; 347 struct lock_object *lock; 348 int spincount, gen; 349 int locksheld __unused; 350 351 record = __containerof(cr, struct epoch_record, er_record); 352 td = curthread; 353 locksheld = td->td_locks; 354 spincount = 0; 355 counter_u64_add(block_count, 1); 356 /* 357 * We lost a race and there's no longer any threads 358 * on the CPU in an epoch section. 359 */ 360 if (TAILQ_EMPTY(&record->er_tdlist)) 361 return; 362 363 if (record->er_cpuid != curcpu) { 364 /* 365 * If the head of the list is running, we can wait for it 366 * to remove itself from the list and thus save us the 367 * overhead of a migration 368 */ 369 gen = record->er_gen; 370 thread_unlock(td); 371 /* 372 * We can't actually check if the waiting thread is running 373 * so we simply poll for it to exit before giving up and 374 * migrating. 375 */ 376 do { 377 cpu_spinwait(); 378 } while (!TAILQ_EMPTY(&record->er_tdlist) && 379 gen == record->er_gen && 380 spincount++ < MAX_ADAPTIVE_SPIN); 381 thread_lock(td); 382 /* 383 * If the generation has changed we can poll again 384 * otherwise we need to migrate. 385 */ 386 if (gen != record->er_gen) 387 return; 388 /* 389 * Being on the same CPU as that of the record on which 390 * we need to wait allows us access to the thread 391 * list associated with that CPU. We can then examine the 392 * oldest thread in the queue and wait on its turnstile 393 * until it resumes and so on until a grace period 394 * elapses. 395 * 396 */ 397 counter_u64_add(migrate_count, 1); 398 sched_bind(td, record->er_cpuid); 399 /* 400 * At this point we need to return to the ck code 401 * to scan to see if a grace period has elapsed. 402 * We can't move on to check the thread list, because 403 * in the meantime new threads may have arrived that 404 * in fact belong to a different epoch. 405 */ 406 return; 407 } 408 /* 409 * Try to find a thread in an epoch section on this CPU 410 * waiting on a turnstile. Otherwise find the lowest 411 * priority thread (highest prio value) and drop our priority 412 * to match to allow it to run. 413 */ 414 TAILQ_FOREACH(tdwait, &record->er_tdlist, et_link) { 415 /* 416 * Propagate our priority to any other waiters to prevent us 417 * from starving them. They will have their original priority 418 * restore on exit from epoch_wait(). 419 */ 420 curwaittd = tdwait->et_td; 421 if (!TD_IS_INHIBITED(curwaittd) && curwaittd->td_priority > td->td_priority) { 422 critical_enter(); 423 thread_unlock(td); 424 thread_lock(curwaittd); 425 sched_prio(curwaittd, td->td_priority); 426 thread_unlock(curwaittd); 427 thread_lock(td); 428 critical_exit(); 429 } 430 if (TD_IS_INHIBITED(curwaittd) && TD_ON_LOCK(curwaittd) && 431 ((ts = curwaittd->td_blocked) != NULL)) { 432 /* 433 * We unlock td to allow turnstile_wait to reacquire 434 * the thread lock. Before unlocking it we enter a 435 * critical section to prevent preemption after we 436 * reenable interrupts by dropping the thread lock in 437 * order to prevent curwaittd from getting to run. 438 */ 439 critical_enter(); 440 thread_unlock(td); 441 owner = turnstile_lock(ts, &lock); 442 /* 443 * The owner pointer indicates that the lock succeeded. 444 * Only in case we hold the lock and the turnstile we 445 * locked is still the one that curwaittd is blocked on 446 * can we continue. Otherwise the turnstile pointer has 447 * been changed out from underneath us, as in the case 448 * where the lock holder has signalled curwaittd, 449 * and we need to continue. 450 */ 451 if (owner != NULL && ts == curwaittd->td_blocked) { 452 MPASS(TD_IS_INHIBITED(curwaittd) && 453 TD_ON_LOCK(curwaittd)); 454 critical_exit(); 455 turnstile_wait(ts, owner, curwaittd->td_tsqueue); 456 counter_u64_add(turnstile_count, 1); 457 thread_lock(td); 458 return; 459 } else if (owner != NULL) 460 turnstile_unlock(ts, lock); 461 thread_lock(td); 462 critical_exit(); 463 KASSERT(td->td_locks == locksheld, 464 ("%d extra locks held", td->td_locks - locksheld)); 465 } 466 } 467 /* 468 * We didn't find any threads actually blocked on a lock 469 * so we have nothing to do except context switch away. 470 */ 471 counter_u64_add(switch_count, 1); 472 mi_switch(SW_VOL | SWT_RELINQUISH, NULL); 473 474 /* 475 * Release the thread lock while yielding to 476 * allow other threads to acquire the lock 477 * pointed to by TDQ_LOCKPTR(td). Else a 478 * deadlock like situation might happen. (HPS) 479 */ 480 thread_unlock(td); 481 thread_lock(td); 482 } 483 484 void 485 epoch_wait_preempt(epoch_t epoch) 486 { 487 struct thread *td; 488 int was_bound; 489 int old_cpu; 490 int old_pinned; 491 u_char old_prio; 492 int locks __unused; 493 494 MPASS(cold || epoch != NULL); 495 INIT_CHECK(epoch); 496 td = curthread; 497 #ifdef INVARIANTS 498 locks = curthread->td_locks; 499 MPASS(epoch->e_flags & EPOCH_PREEMPT); 500 if ((epoch->e_flags & EPOCH_LOCKED) == 0) 501 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 502 "epoch_wait() can be long running"); 503 KASSERT(!in_epoch(epoch), ("epoch_wait_preempt() called in the middle " 504 "of an epoch section of the same epoch")); 505 #endif 506 thread_lock(td); 507 DROP_GIANT(); 508 509 old_cpu = PCPU_GET(cpuid); 510 old_pinned = td->td_pinned; 511 old_prio = td->td_priority; 512 was_bound = sched_is_bound(td); 513 sched_unbind(td); 514 td->td_pinned = 0; 515 sched_bind(td, old_cpu); 516 517 ck_epoch_synchronize_wait(&epoch->e_epoch, epoch_block_handler_preempt, 518 NULL); 519 520 /* restore CPU binding, if any */ 521 if (was_bound != 0) { 522 sched_bind(td, old_cpu); 523 } else { 524 /* get thread back to initial CPU, if any */ 525 if (old_pinned != 0) 526 sched_bind(td, old_cpu); 527 sched_unbind(td); 528 } 529 /* restore pinned after bind */ 530 td->td_pinned = old_pinned; 531 532 /* restore thread priority */ 533 sched_prio(td, old_prio); 534 thread_unlock(td); 535 PICKUP_GIANT(); 536 KASSERT(td->td_locks == locks, 537 ("%d residual locks held", td->td_locks - locks)); 538 } 539 540 static void 541 epoch_block_handler(struct ck_epoch *g __unused, ck_epoch_record_t *c __unused, 542 void *arg __unused) 543 { 544 cpu_spinwait(); 545 } 546 547 void 548 epoch_wait(epoch_t epoch) 549 { 550 551 MPASS(cold || epoch != NULL); 552 INIT_CHECK(epoch); 553 MPASS(epoch->e_flags == 0); 554 critical_enter(); 555 ck_epoch_synchronize_wait(&epoch->e_epoch, epoch_block_handler, NULL); 556 critical_exit(); 557 } 558 559 void 560 epoch_call(epoch_t epoch, epoch_context_t ctx, void (*callback) (epoch_context_t)) 561 { 562 epoch_record_t er; 563 ck_epoch_entry_t *cb; 564 565 cb = (void *)ctx; 566 567 MPASS(callback); 568 /* too early in boot to have epoch set up */ 569 if (__predict_false(epoch == NULL)) 570 goto boottime; 571 #if !defined(EARLY_AP_STARTUP) 572 if (__predict_false(inited < 2)) 573 goto boottime; 574 #endif 575 576 critical_enter(); 577 *DPCPU_PTR(epoch_cb_count) += 1; 578 er = epoch_currecord(epoch); 579 ck_epoch_call(&er->er_record, cb, (ck_epoch_cb_t *)callback); 580 critical_exit(); 581 return; 582 boottime: 583 callback(ctx); 584 } 585 586 static void 587 epoch_call_task(void *arg __unused) 588 { 589 ck_stack_entry_t *cursor, *head, *next; 590 ck_epoch_record_t *record; 591 epoch_record_t er; 592 epoch_t epoch; 593 ck_stack_t cb_stack; 594 int i, npending, total; 595 596 ck_stack_init(&cb_stack); 597 critical_enter(); 598 epoch_enter(global_epoch); 599 for (total = i = 0; i < epoch_count; i++) { 600 if (__predict_false((epoch = allepochs[i]) == NULL)) 601 continue; 602 er = epoch_currecord(epoch); 603 record = &er->er_record; 604 if ((npending = record->n_pending) == 0) 605 continue; 606 ck_epoch_poll_deferred(record, &cb_stack); 607 total += npending - record->n_pending; 608 } 609 epoch_exit(global_epoch); 610 *DPCPU_PTR(epoch_cb_count) -= total; 611 critical_exit(); 612 613 counter_u64_add(epoch_call_count, total); 614 counter_u64_add(epoch_call_task_count, 1); 615 616 head = ck_stack_batch_pop_npsc(&cb_stack); 617 for (cursor = head; cursor != NULL; cursor = next) { 618 struct ck_epoch_entry *entry = 619 ck_epoch_entry_container(cursor); 620 621 next = CK_STACK_NEXT(cursor); 622 entry->function(entry); 623 } 624 } 625 626 int 627 in_epoch_verbose(epoch_t epoch, int dump_onfail) 628 { 629 struct epoch_tracker *tdwait; 630 struct thread *td; 631 epoch_record_t er; 632 633 td = curthread; 634 if (td->td_epochnest == 0) 635 return (0); 636 if (__predict_false((epoch) == NULL)) 637 return (0); 638 critical_enter(); 639 er = epoch_currecord(epoch); 640 TAILQ_FOREACH(tdwait, &er->er_tdlist, et_link) 641 if (tdwait->et_td == td) { 642 critical_exit(); 643 return (1); 644 } 645 #ifdef INVARIANTS 646 if (dump_onfail) { 647 MPASS(td->td_pinned); 648 printf("cpu: %d id: %d\n", curcpu, td->td_tid); 649 TAILQ_FOREACH(tdwait, &er->er_tdlist, et_link) 650 printf("td_tid: %d ", tdwait->et_td->td_tid); 651 printf("\n"); 652 } 653 #endif 654 critical_exit(); 655 return (0); 656 } 657 658 int 659 in_epoch(epoch_t epoch) 660 { 661 return (in_epoch_verbose(epoch, 0)); 662 } 663 664 static void 665 epoch_drain_cb(struct epoch_context *ctx) 666 { 667 struct epoch *epoch = 668 __containerof(ctx, struct epoch_record, er_drain_ctx)->er_parent; 669 670 if (atomic_fetchadd_int(&epoch->e_drain_count, -1) == 1) { 671 mtx_lock(&epoch->e_drain_mtx); 672 wakeup(epoch); 673 mtx_unlock(&epoch->e_drain_mtx); 674 } 675 } 676 677 void 678 epoch_drain_callbacks(epoch_t epoch) 679 { 680 epoch_record_t er; 681 struct thread *td; 682 int was_bound; 683 int old_pinned; 684 int old_cpu; 685 int cpu; 686 687 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 688 "epoch_drain_callbacks() may sleep!"); 689 690 /* too early in boot to have epoch set up */ 691 if (__predict_false(epoch == NULL)) 692 return; 693 #if !defined(EARLY_AP_STARTUP) 694 if (__predict_false(inited < 2)) 695 return; 696 #endif 697 DROP_GIANT(); 698 699 sx_xlock(&epoch->e_drain_sx); 700 mtx_lock(&epoch->e_drain_mtx); 701 702 td = curthread; 703 thread_lock(td); 704 old_cpu = PCPU_GET(cpuid); 705 old_pinned = td->td_pinned; 706 was_bound = sched_is_bound(td); 707 sched_unbind(td); 708 td->td_pinned = 0; 709 710 CPU_FOREACH(cpu) 711 epoch->e_drain_count++; 712 CPU_FOREACH(cpu) { 713 er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu); 714 sched_bind(td, cpu); 715 epoch_call(epoch, &er->er_drain_ctx, &epoch_drain_cb); 716 } 717 718 /* restore CPU binding, if any */ 719 if (was_bound != 0) { 720 sched_bind(td, old_cpu); 721 } else { 722 /* get thread back to initial CPU, if any */ 723 if (old_pinned != 0) 724 sched_bind(td, old_cpu); 725 sched_unbind(td); 726 } 727 /* restore pinned after bind */ 728 td->td_pinned = old_pinned; 729 730 thread_unlock(td); 731 732 while (epoch->e_drain_count != 0) 733 msleep(epoch, &epoch->e_drain_mtx, PZERO, "EDRAIN", 0); 734 735 mtx_unlock(&epoch->e_drain_mtx); 736 sx_xunlock(&epoch->e_drain_sx); 737 738 PICKUP_GIANT(); 739 } 740 741 void 742 epoch_thread_init(struct thread *td) 743 { 744 745 td->td_et = malloc(sizeof(struct epoch_tracker), M_EPOCH, M_WAITOK); 746 } 747 748 void 749 epoch_thread_fini(struct thread *td) 750 { 751 752 free(td->td_et, M_EPOCH); 753 } 754