1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (C) 2001 Julian Elischer <julian@freebsd.org>. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice(s), this list of conditions and the following disclaimer as 12 * the first lines of this file unmodified other than the possible 13 * addition of one or more copyright notices. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice(s), this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 19 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 21 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 22 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 25 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 28 * DAMAGE. 29 */ 30 31 #include "opt_witness.h" 32 #include "opt_hwpmc_hooks.h" 33 34 #include <sys/systm.h> 35 #include <sys/asan.h> 36 #include <sys/kernel.h> 37 #include <sys/lock.h> 38 #include <sys/msan.h> 39 #include <sys/mutex.h> 40 #include <sys/proc.h> 41 #include <sys/bitstring.h> 42 #include <sys/epoch.h> 43 #include <sys/rangelock.h> 44 #include <sys/resourcevar.h> 45 #include <sys/sdt.h> 46 #include <sys/smp.h> 47 #include <sys/sched.h> 48 #include <sys/sleepqueue.h> 49 #include <sys/selinfo.h> 50 #include <sys/syscallsubr.h> 51 #include <sys/dtrace_bsd.h> 52 #include <sys/sysent.h> 53 #include <sys/turnstile.h> 54 #include <sys/taskqueue.h> 55 #include <sys/ktr.h> 56 #include <sys/rwlock.h> 57 #include <sys/umtxvar.h> 58 #include <sys/vmmeter.h> 59 #include <sys/cpuset.h> 60 #ifdef HWPMC_HOOKS 61 #include <sys/pmckern.h> 62 #endif 63 #include <sys/priv.h> 64 65 #include <security/audit/audit.h> 66 67 #include <vm/pmap.h> 68 #include <vm/vm.h> 69 #include <vm/vm_extern.h> 70 #include <vm/uma.h> 71 #include <vm/vm_phys.h> 72 #include <sys/eventhandler.h> 73 74 /* 75 * Asserts below verify the stability of struct thread and struct proc 76 * layout, as exposed by KBI to modules. On head, the KBI is allowed 77 * to drift, change to the structures must be accompanied by the 78 * assert update. 79 * 80 * On the stable branches after KBI freeze, conditions must not be 81 * violated. Typically new fields are moved to the end of the 82 * structures. 83 */ 84 #ifdef __amd64__ 85 _Static_assert(offsetof(struct thread, td_flags) == 0x108, 86 "struct thread KBI td_flags"); 87 _Static_assert(offsetof(struct thread, td_pflags) == 0x114, 88 "struct thread KBI td_pflags"); 89 _Static_assert(offsetof(struct thread, td_frame) == 0x4b8, 90 "struct thread KBI td_frame"); 91 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6c0, 92 "struct thread KBI td_emuldata"); 93 _Static_assert(offsetof(struct proc, p_flag) == 0xb8, 94 "struct proc KBI p_flag"); 95 _Static_assert(offsetof(struct proc, p_pid) == 0xc4, 96 "struct proc KBI p_pid"); 97 _Static_assert(offsetof(struct proc, p_filemon) == 0x3c8, 98 "struct proc KBI p_filemon"); 99 _Static_assert(offsetof(struct proc, p_comm) == 0x3e0, 100 "struct proc KBI p_comm"); 101 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4d0, 102 "struct proc KBI p_emuldata"); 103 #endif 104 #ifdef __i386__ 105 _Static_assert(offsetof(struct thread, td_flags) == 0x9c, 106 "struct thread KBI td_flags"); 107 _Static_assert(offsetof(struct thread, td_pflags) == 0xa8, 108 "struct thread KBI td_pflags"); 109 _Static_assert(offsetof(struct thread, td_frame) == 0x318, 110 "struct thread KBI td_frame"); 111 _Static_assert(offsetof(struct thread, td_emuldata) == 0x35c, 112 "struct thread KBI td_emuldata"); 113 _Static_assert(offsetof(struct proc, p_flag) == 0x6c, 114 "struct proc KBI p_flag"); 115 _Static_assert(offsetof(struct proc, p_pid) == 0x78, 116 "struct proc KBI p_pid"); 117 _Static_assert(offsetof(struct proc, p_filemon) == 0x270, 118 "struct proc KBI p_filemon"); 119 _Static_assert(offsetof(struct proc, p_comm) == 0x284, 120 "struct proc KBI p_comm"); 121 _Static_assert(offsetof(struct proc, p_emuldata) == 0x318, 122 "struct proc KBI p_emuldata"); 123 #endif 124 125 SDT_PROVIDER_DECLARE(proc); 126 SDT_PROBE_DEFINE(proc, , , lwp__exit); 127 128 /* 129 * thread related storage. 130 */ 131 static uma_zone_t thread_zone; 132 133 struct thread_domain_data { 134 struct thread *tdd_zombies; 135 int tdd_reapticks; 136 } __aligned(CACHE_LINE_SIZE); 137 138 static struct thread_domain_data thread_domain_data[MAXMEMDOM]; 139 140 static struct task thread_reap_task; 141 static struct callout thread_reap_callout; 142 143 static void thread_zombie(struct thread *); 144 static void thread_reap(void); 145 static void thread_reap_all(void); 146 static void thread_reap_task_cb(void *, int); 147 static void thread_reap_callout_cb(void *); 148 static void thread_unsuspend_one(struct thread *td, struct proc *p, 149 bool boundary); 150 static void thread_free_batched(struct thread *td); 151 152 static __exclusive_cache_line struct mtx tid_lock; 153 static bitstr_t *tid_bitmap; 154 155 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 156 157 static int maxthread; 158 SYSCTL_INT(_kern, OID_AUTO, maxthread, CTLFLAG_RDTUN, 159 &maxthread, 0, "Maximum number of threads"); 160 161 static __exclusive_cache_line int nthreads; 162 163 static LIST_HEAD(tidhashhead, thread) *tidhashtbl; 164 static u_long tidhash; 165 static u_long tidhashlock; 166 static struct rwlock *tidhashtbl_lock; 167 #define TIDHASH(tid) (&tidhashtbl[(tid) & tidhash]) 168 #define TIDHASHLOCK(tid) (&tidhashtbl_lock[(tid) & tidhashlock]) 169 170 EVENTHANDLER_LIST_DEFINE(thread_ctor); 171 EVENTHANDLER_LIST_DEFINE(thread_dtor); 172 EVENTHANDLER_LIST_DEFINE(thread_init); 173 EVENTHANDLER_LIST_DEFINE(thread_fini); 174 175 static bool 176 thread_count_inc_try(void) 177 { 178 int nthreads_new; 179 180 nthreads_new = atomic_fetchadd_int(&nthreads, 1) + 1; 181 if (nthreads_new >= maxthread - 100) { 182 if (priv_check_cred(curthread->td_ucred, PRIV_MAXPROC) != 0 || 183 nthreads_new >= maxthread) { 184 atomic_subtract_int(&nthreads, 1); 185 return (false); 186 } 187 } 188 return (true); 189 } 190 191 static bool 192 thread_count_inc(void) 193 { 194 static struct timeval lastfail; 195 static int curfail; 196 197 thread_reap(); 198 if (thread_count_inc_try()) { 199 return (true); 200 } 201 202 thread_reap_all(); 203 if (thread_count_inc_try()) { 204 return (true); 205 } 206 207 if (ppsratecheck(&lastfail, &curfail, 1)) { 208 printf("maxthread limit exceeded by uid %u " 209 "(pid %d); consider increasing kern.maxthread\n", 210 curthread->td_ucred->cr_ruid, curproc->p_pid); 211 } 212 return (false); 213 } 214 215 static void 216 thread_count_sub(int n) 217 { 218 219 atomic_subtract_int(&nthreads, n); 220 } 221 222 static void 223 thread_count_dec(void) 224 { 225 226 thread_count_sub(1); 227 } 228 229 static lwpid_t 230 tid_alloc(void) 231 { 232 static lwpid_t trytid; 233 lwpid_t tid; 234 235 mtx_lock(&tid_lock); 236 /* 237 * It is an invariant that the bitmap is big enough to hold maxthread 238 * IDs. If we got to this point there has to be at least one free. 239 */ 240 if (trytid >= maxthread) 241 trytid = 0; 242 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 243 if (tid == -1) { 244 KASSERT(trytid != 0, ("unexpectedly ran out of IDs")); 245 trytid = 0; 246 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 247 KASSERT(tid != -1, ("unexpectedly ran out of IDs")); 248 } 249 bit_set(tid_bitmap, tid); 250 trytid = tid + 1; 251 mtx_unlock(&tid_lock); 252 return (tid + NO_PID); 253 } 254 255 static void 256 tid_free_locked(lwpid_t rtid) 257 { 258 lwpid_t tid; 259 260 mtx_assert(&tid_lock, MA_OWNED); 261 KASSERT(rtid >= NO_PID, 262 ("%s: invalid tid %d\n", __func__, rtid)); 263 tid = rtid - NO_PID; 264 KASSERT(bit_test(tid_bitmap, tid) != 0, 265 ("thread ID %d not allocated\n", rtid)); 266 bit_clear(tid_bitmap, tid); 267 } 268 269 static void 270 tid_free(lwpid_t rtid) 271 { 272 273 mtx_lock(&tid_lock); 274 tid_free_locked(rtid); 275 mtx_unlock(&tid_lock); 276 } 277 278 static void 279 tid_free_batch(lwpid_t *batch, int n) 280 { 281 int i; 282 283 mtx_lock(&tid_lock); 284 for (i = 0; i < n; i++) { 285 tid_free_locked(batch[i]); 286 } 287 mtx_unlock(&tid_lock); 288 } 289 290 /* 291 * Batching for thread reapping. 292 */ 293 struct tidbatch { 294 lwpid_t tab[16]; 295 int n; 296 }; 297 298 static void 299 tidbatch_prep(struct tidbatch *tb) 300 { 301 302 tb->n = 0; 303 } 304 305 static void 306 tidbatch_add(struct tidbatch *tb, struct thread *td) 307 { 308 309 KASSERT(tb->n < nitems(tb->tab), 310 ("%s: count too high %d", __func__, tb->n)); 311 tb->tab[tb->n] = td->td_tid; 312 tb->n++; 313 } 314 315 static void 316 tidbatch_process(struct tidbatch *tb) 317 { 318 319 KASSERT(tb->n <= nitems(tb->tab), 320 ("%s: count too high %d", __func__, tb->n)); 321 if (tb->n == nitems(tb->tab)) { 322 tid_free_batch(tb->tab, tb->n); 323 tb->n = 0; 324 } 325 } 326 327 static void 328 tidbatch_final(struct tidbatch *tb) 329 { 330 331 KASSERT(tb->n <= nitems(tb->tab), 332 ("%s: count too high %d", __func__, tb->n)); 333 if (tb->n != 0) { 334 tid_free_batch(tb->tab, tb->n); 335 } 336 } 337 338 /* 339 * Batching thread count free, for consistency 340 */ 341 struct tdcountbatch { 342 int n; 343 }; 344 345 static void 346 tdcountbatch_prep(struct tdcountbatch *tb) 347 { 348 349 tb->n = 0; 350 } 351 352 static void 353 tdcountbatch_add(struct tdcountbatch *tb, struct thread *td __unused) 354 { 355 356 tb->n++; 357 } 358 359 static void 360 tdcountbatch_process(struct tdcountbatch *tb) 361 { 362 363 if (tb->n == 32) { 364 thread_count_sub(tb->n); 365 tb->n = 0; 366 } 367 } 368 369 static void 370 tdcountbatch_final(struct tdcountbatch *tb) 371 { 372 373 if (tb->n != 0) { 374 thread_count_sub(tb->n); 375 } 376 } 377 378 /* 379 * Prepare a thread for use. 380 */ 381 static int 382 thread_ctor(void *mem, int size, void *arg, int flags) 383 { 384 struct thread *td; 385 386 td = (struct thread *)mem; 387 TD_SET_STATE(td, TDS_INACTIVE); 388 td->td_lastcpu = td->td_oncpu = NOCPU; 389 390 /* 391 * Note that td_critnest begins life as 1 because the thread is not 392 * running and is thereby implicitly waiting to be on the receiving 393 * end of a context switch. 394 */ 395 td->td_critnest = 1; 396 td->td_lend_user_pri = PRI_MAX; 397 #ifdef AUDIT 398 audit_thread_alloc(td); 399 #endif 400 #ifdef KDTRACE_HOOKS 401 kdtrace_thread_ctor(td); 402 #endif 403 umtx_thread_alloc(td); 404 MPASS(td->td_sel == NULL); 405 return (0); 406 } 407 408 /* 409 * Reclaim a thread after use. 410 */ 411 static void 412 thread_dtor(void *mem, int size, void *arg) 413 { 414 struct thread *td; 415 416 td = (struct thread *)mem; 417 418 #ifdef INVARIANTS 419 /* Verify that this thread is in a safe state to free. */ 420 switch (TD_GET_STATE(td)) { 421 case TDS_INHIBITED: 422 case TDS_RUNNING: 423 case TDS_CAN_RUN: 424 case TDS_RUNQ: 425 /* 426 * We must never unlink a thread that is in one of 427 * these states, because it is currently active. 428 */ 429 panic("bad state for thread unlinking"); 430 /* NOTREACHED */ 431 case TDS_INACTIVE: 432 break; 433 default: 434 panic("bad thread state"); 435 /* NOTREACHED */ 436 } 437 #endif 438 #ifdef AUDIT 439 audit_thread_free(td); 440 #endif 441 #ifdef KDTRACE_HOOKS 442 kdtrace_thread_dtor(td); 443 #endif 444 /* Free all OSD associated to this thread. */ 445 osd_thread_exit(td); 446 ast_kclear(td); 447 seltdfini(td); 448 } 449 450 /* 451 * Initialize type-stable parts of a thread (when newly created). 452 */ 453 static int 454 thread_init(void *mem, int size, int flags) 455 { 456 struct thread *td; 457 458 td = (struct thread *)mem; 459 460 td->td_allocdomain = vm_phys_domain(vtophys(td)); 461 td->td_sleepqueue = sleepq_alloc(); 462 td->td_turnstile = turnstile_alloc(); 463 EVENTHANDLER_DIRECT_INVOKE(thread_init, td); 464 umtx_thread_init(td); 465 td->td_kstack = 0; 466 td->td_sel = NULL; 467 return (0); 468 } 469 470 /* 471 * Tear down type-stable parts of a thread (just before being discarded). 472 */ 473 static void 474 thread_fini(void *mem, int size) 475 { 476 struct thread *td; 477 478 td = (struct thread *)mem; 479 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td); 480 turnstile_free(td->td_turnstile); 481 sleepq_free(td->td_sleepqueue); 482 umtx_thread_fini(td); 483 MPASS(td->td_sel == NULL); 484 } 485 486 /* 487 * For a newly created process, 488 * link up all the structures and its initial threads etc. 489 * called from: 490 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 491 * proc_dtor() (should go away) 492 * proc_init() 493 */ 494 void 495 proc_linkup0(struct proc *p, struct thread *td) 496 { 497 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 498 proc_linkup(p, td); 499 } 500 501 void 502 proc_linkup(struct proc *p, struct thread *td) 503 { 504 505 sigqueue_init(&p->p_sigqueue, p); 506 p->p_ksi = ksiginfo_alloc(M_WAITOK); 507 if (p->p_ksi != NULL) { 508 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 509 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 510 } 511 LIST_INIT(&p->p_mqnotifier); 512 p->p_numthreads = 0; 513 thread_link(td, p); 514 } 515 516 static void 517 ast_suspend(struct thread *td, int tda __unused) 518 { 519 struct proc *p; 520 521 p = td->td_proc; 522 /* 523 * We need to check to see if we have to exit or wait due to a 524 * single threading requirement or some other STOP condition. 525 */ 526 PROC_LOCK(p); 527 thread_suspend_check(0); 528 PROC_UNLOCK(p); 529 } 530 531 extern int max_threads_per_proc; 532 533 /* 534 * Initialize global thread allocation resources. 535 */ 536 void 537 threadinit(void) 538 { 539 u_long i; 540 lwpid_t tid0; 541 542 /* 543 * Place an upper limit on threads which can be allocated. 544 * 545 * Note that other factors may make the de facto limit much lower. 546 * 547 * Platform limits are somewhat arbitrary but deemed "more than good 548 * enough" for the foreseable future. 549 */ 550 if (maxthread == 0) { 551 #ifdef _LP64 552 maxthread = MIN(maxproc * max_threads_per_proc, 1000000); 553 #else 554 maxthread = MIN(maxproc * max_threads_per_proc, 100000); 555 #endif 556 } 557 558 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 559 tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK); 560 /* 561 * Handle thread0. 562 */ 563 thread_count_inc(); 564 tid0 = tid_alloc(); 565 if (tid0 != THREAD0_TID) 566 panic("tid0 %d != %d\n", tid0, THREAD0_TID); 567 568 /* 569 * Thread structures are specially aligned so that (at least) the 570 * 5 lower bits of a pointer to 'struct thead' must be 0. These bits 571 * are used by synchronization primitives to store flags in pointers to 572 * such structures. 573 */ 574 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 575 thread_ctor, thread_dtor, thread_init, thread_fini, 576 UMA_ALIGN_CACHE_AND_MASK(32 - 1), UMA_ZONE_NOFREE); 577 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 578 tidhashlock = (tidhash + 1) / 64; 579 if (tidhashlock > 0) 580 tidhashlock--; 581 tidhashtbl_lock = malloc(sizeof(*tidhashtbl_lock) * (tidhashlock + 1), 582 M_TIDHASH, M_WAITOK | M_ZERO); 583 for (i = 0; i < tidhashlock + 1; i++) 584 rw_init(&tidhashtbl_lock[i], "tidhash"); 585 586 TASK_INIT(&thread_reap_task, 0, thread_reap_task_cb, NULL); 587 callout_init(&thread_reap_callout, 1); 588 callout_reset(&thread_reap_callout, 5 * hz, 589 thread_reap_callout_cb, NULL); 590 ast_register(TDA_SUSPEND, ASTR_ASTF_REQUIRED, 0, ast_suspend); 591 } 592 593 /* 594 * Place an unused thread on the zombie list. 595 */ 596 void 597 thread_zombie(struct thread *td) 598 { 599 struct thread_domain_data *tdd; 600 struct thread *ztd; 601 602 tdd = &thread_domain_data[td->td_allocdomain]; 603 ztd = atomic_load_ptr(&tdd->tdd_zombies); 604 for (;;) { 605 td->td_zombie = ztd; 606 if (atomic_fcmpset_rel_ptr((uintptr_t *)&tdd->tdd_zombies, 607 (uintptr_t *)&ztd, (uintptr_t)td)) 608 break; 609 continue; 610 } 611 } 612 613 /* 614 * Release a thread that has exited after cpu_throw(). 615 */ 616 void 617 thread_stash(struct thread *td) 618 { 619 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 620 thread_zombie(td); 621 } 622 623 /* 624 * Reap zombies from passed domain. 625 */ 626 static void 627 thread_reap_domain(struct thread_domain_data *tdd) 628 { 629 struct thread *itd, *ntd; 630 struct tidbatch tidbatch; 631 struct credbatch credbatch; 632 struct limbatch limbatch; 633 struct tdcountbatch tdcountbatch; 634 635 /* 636 * Reading upfront is pessimal if followed by concurrent atomic_swap, 637 * but most of the time the list is empty. 638 */ 639 if (tdd->tdd_zombies == NULL) 640 return; 641 642 itd = (struct thread *)atomic_swap_ptr((uintptr_t *)&tdd->tdd_zombies, 643 (uintptr_t)NULL); 644 if (itd == NULL) 645 return; 646 647 /* 648 * Multiple CPUs can get here, the race is fine as ticks is only 649 * advisory. 650 */ 651 tdd->tdd_reapticks = ticks; 652 653 tidbatch_prep(&tidbatch); 654 credbatch_prep(&credbatch); 655 limbatch_prep(&limbatch); 656 tdcountbatch_prep(&tdcountbatch); 657 658 while (itd != NULL) { 659 ntd = itd->td_zombie; 660 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, itd); 661 662 tidbatch_add(&tidbatch, itd); 663 credbatch_add(&credbatch, itd); 664 limbatch_add(&limbatch, itd); 665 tdcountbatch_add(&tdcountbatch, itd); 666 667 thread_free_batched(itd); 668 669 tidbatch_process(&tidbatch); 670 credbatch_process(&credbatch); 671 limbatch_process(&limbatch); 672 tdcountbatch_process(&tdcountbatch); 673 674 itd = ntd; 675 } 676 677 tidbatch_final(&tidbatch); 678 credbatch_final(&credbatch); 679 limbatch_final(&limbatch); 680 tdcountbatch_final(&tdcountbatch); 681 } 682 683 /* 684 * Reap zombies from all domains. 685 */ 686 static void 687 thread_reap_all(void) 688 { 689 struct thread_domain_data *tdd; 690 int i, domain; 691 692 domain = PCPU_GET(domain); 693 for (i = 0; i < vm_ndomains; i++) { 694 tdd = &thread_domain_data[(i + domain) % vm_ndomains]; 695 thread_reap_domain(tdd); 696 } 697 } 698 699 /* 700 * Reap zombies from local domain. 701 */ 702 static void 703 thread_reap(void) 704 { 705 struct thread_domain_data *tdd; 706 int domain; 707 708 domain = PCPU_GET(domain); 709 tdd = &thread_domain_data[domain]; 710 711 thread_reap_domain(tdd); 712 } 713 714 static void 715 thread_reap_task_cb(void *arg __unused, int pending __unused) 716 { 717 718 thread_reap_all(); 719 } 720 721 static void 722 thread_reap_callout_cb(void *arg __unused) 723 { 724 struct thread_domain_data *tdd; 725 int i, cticks, lticks; 726 bool wantreap; 727 728 wantreap = false; 729 cticks = atomic_load_int(&ticks); 730 for (i = 0; i < vm_ndomains; i++) { 731 tdd = &thread_domain_data[i]; 732 lticks = tdd->tdd_reapticks; 733 if (tdd->tdd_zombies != NULL && 734 (u_int)(cticks - lticks) > 5 * hz) { 735 wantreap = true; 736 break; 737 } 738 } 739 740 if (wantreap) 741 taskqueue_enqueue(taskqueue_thread, &thread_reap_task); 742 callout_reset(&thread_reap_callout, 5 * hz, 743 thread_reap_callout_cb, NULL); 744 } 745 746 /* 747 * Calling this function guarantees that any thread that exited before 748 * the call is reaped when the function returns. By 'exited' we mean 749 * a thread removed from the process linkage with thread_unlink(). 750 * Practically this means that caller must lock/unlock corresponding 751 * process lock before the call, to synchronize with thread_exit(). 752 */ 753 void 754 thread_reap_barrier(void) 755 { 756 struct task *t; 757 758 /* 759 * First do context switches to each CPU to ensure that all 760 * PCPU pc_deadthreads are moved to zombie list. 761 */ 762 quiesce_all_cpus("", PDROP); 763 764 /* 765 * Second, fire the task in the same thread as normal 766 * thread_reap() is done, to serialize reaping. 767 */ 768 t = malloc(sizeof(*t), M_TEMP, M_WAITOK); 769 TASK_INIT(t, 0, thread_reap_task_cb, t); 770 taskqueue_enqueue(taskqueue_thread, t); 771 taskqueue_drain(taskqueue_thread, t); 772 free(t, M_TEMP); 773 } 774 775 /* 776 * Allocate a thread. 777 */ 778 struct thread * 779 thread_alloc(int pages) 780 { 781 struct thread *td; 782 lwpid_t tid; 783 784 if (!thread_count_inc()) { 785 return (NULL); 786 } 787 788 tid = tid_alloc(); 789 td = uma_zalloc(thread_zone, M_WAITOK); 790 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 791 if (!vm_thread_new(td, pages)) { 792 uma_zfree(thread_zone, td); 793 tid_free(tid); 794 thread_count_dec(); 795 return (NULL); 796 } 797 td->td_tid = tid; 798 bzero(&td->td_sa.args, sizeof(td->td_sa.args)); 799 kasan_thread_alloc(td); 800 kmsan_thread_alloc(td); 801 cpu_thread_alloc(td); 802 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); 803 return (td); 804 } 805 806 int 807 thread_recycle(struct thread *td, int pages) 808 { 809 if (td->td_kstack == 0 || td->td_kstack_pages != pages) { 810 if (td->td_kstack != 0) 811 vm_thread_dispose(td); 812 if (!vm_thread_new(td, pages)) 813 return (ENOMEM); 814 cpu_thread_alloc(td); 815 } 816 kasan_thread_alloc(td); 817 kmsan_thread_alloc(td); 818 return (0); 819 } 820 821 /* 822 * Deallocate a thread. 823 */ 824 static void 825 thread_free_batched(struct thread *td) 826 { 827 828 lock_profile_thread_exit(td); 829 if (td->td_cpuset) 830 cpuset_rel(td->td_cpuset); 831 td->td_cpuset = NULL; 832 cpu_thread_free(td); 833 if (td->td_kstack != 0) 834 vm_thread_dispose(td); 835 callout_drain(&td->td_slpcallout); 836 /* 837 * Freeing handled by the caller. 838 */ 839 td->td_tid = -1; 840 kmsan_thread_free(td); 841 uma_zfree(thread_zone, td); 842 } 843 844 void 845 thread_free(struct thread *td) 846 { 847 lwpid_t tid; 848 849 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td); 850 tid = td->td_tid; 851 thread_free_batched(td); 852 tid_free(tid); 853 thread_count_dec(); 854 } 855 856 void 857 thread_cow_get_proc(struct thread *newtd, struct proc *p) 858 { 859 860 PROC_LOCK_ASSERT(p, MA_OWNED); 861 newtd->td_realucred = crcowget(p->p_ucred); 862 newtd->td_ucred = newtd->td_realucred; 863 newtd->td_limit = lim_hold(p->p_limit); 864 newtd->td_cowgen = p->p_cowgen; 865 } 866 867 void 868 thread_cow_get(struct thread *newtd, struct thread *td) 869 { 870 871 MPASS(td->td_realucred == td->td_ucred); 872 newtd->td_realucred = crcowget(td->td_realucred); 873 newtd->td_ucred = newtd->td_realucred; 874 newtd->td_limit = lim_hold(td->td_limit); 875 newtd->td_cowgen = td->td_cowgen; 876 } 877 878 void 879 thread_cow_free(struct thread *td) 880 { 881 882 if (td->td_realucred != NULL) 883 crcowfree(td); 884 if (td->td_limit != NULL) 885 lim_free(td->td_limit); 886 } 887 888 void 889 thread_cow_update(struct thread *td) 890 { 891 struct proc *p; 892 struct ucred *oldcred; 893 struct plimit *oldlimit; 894 895 p = td->td_proc; 896 PROC_LOCK(p); 897 oldcred = crcowsync(); 898 oldlimit = lim_cowsync(); 899 td->td_cowgen = p->p_cowgen; 900 PROC_UNLOCK(p); 901 if (oldcred != NULL) 902 crfree(oldcred); 903 if (oldlimit != NULL) 904 lim_free(oldlimit); 905 } 906 907 void 908 thread_cow_synced(struct thread *td) 909 { 910 struct proc *p; 911 912 p = td->td_proc; 913 PROC_LOCK_ASSERT(p, MA_OWNED); 914 MPASS(td->td_cowgen != p->p_cowgen); 915 MPASS(td->td_ucred == p->p_ucred); 916 MPASS(td->td_limit == p->p_limit); 917 td->td_cowgen = p->p_cowgen; 918 } 919 920 /* 921 * Discard the current thread and exit from its context. 922 * Always called with scheduler locked. 923 * 924 * Because we can't free a thread while we're operating under its context, 925 * push the current thread into our CPU's deadthread holder. This means 926 * we needn't worry about someone else grabbing our context before we 927 * do a cpu_throw(). 928 */ 929 void 930 thread_exit(void) 931 { 932 uint64_t runtime, new_switchtime; 933 struct thread *td; 934 struct thread *td2; 935 struct proc *p; 936 937 td = curthread; 938 p = td->td_proc; 939 940 PROC_SLOCK_ASSERT(p, MA_OWNED); 941 mtx_assert(&Giant, MA_NOTOWNED); 942 943 PROC_LOCK_ASSERT(p, MA_OWNED); 944 KASSERT(p != NULL, ("thread exiting without a process")); 945 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 946 (long)p->p_pid, td->td_name); 947 SDT_PROBE0(proc, , , lwp__exit); 948 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 949 MPASS(td->td_realucred == td->td_ucred); 950 951 /* 952 * drop FPU & debug register state storage, or any other 953 * architecture specific resources that 954 * would not be on a new untouched process. 955 */ 956 cpu_thread_exit(td); 957 958 /* 959 * The last thread is left attached to the process 960 * So that the whole bundle gets recycled. Skip 961 * all this stuff if we never had threads. 962 * EXIT clears all sign of other threads when 963 * it goes to single threading, so the last thread always 964 * takes the short path. 965 */ 966 if (p->p_flag & P_HADTHREADS) { 967 if (p->p_numthreads > 1) { 968 atomic_add_int(&td->td_proc->p_exitthreads, 1); 969 thread_unlink(td); 970 td2 = FIRST_THREAD_IN_PROC(p); 971 sched_exit_thread(td2, td); 972 973 /* 974 * The test below is NOT true if we are the 975 * sole exiting thread. P_STOPPED_SINGLE is unset 976 * in exit1() after it is the only survivor. 977 */ 978 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 979 if (p->p_numthreads == p->p_suspcount) { 980 thread_lock(p->p_singlethread); 981 thread_unsuspend_one(p->p_singlethread, 982 p, false); 983 } 984 } 985 986 PCPU_SET(deadthread, td); 987 } else { 988 /* 989 * The last thread is exiting.. but not through exit() 990 */ 991 panic ("thread_exit: Last thread exiting on its own"); 992 } 993 } 994 #ifdef HWPMC_HOOKS 995 /* 996 * If this thread is part of a process that is being tracked by hwpmc(4), 997 * inform the module of the thread's impending exit. 998 */ 999 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) { 1000 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1001 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL); 1002 } else if (PMC_SYSTEM_SAMPLING_ACTIVE()) 1003 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL); 1004 #endif 1005 PROC_UNLOCK(p); 1006 PROC_STATLOCK(p); 1007 thread_lock(td); 1008 PROC_SUNLOCK(p); 1009 1010 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 1011 new_switchtime = cpu_ticks(); 1012 runtime = new_switchtime - PCPU_GET(switchtime); 1013 td->td_runtime += runtime; 1014 td->td_incruntime += runtime; 1015 PCPU_SET(switchtime, new_switchtime); 1016 PCPU_SET(switchticks, ticks); 1017 VM_CNT_INC(v_swtch); 1018 1019 /* Save our resource usage in our process. */ 1020 td->td_ru.ru_nvcsw++; 1021 ruxagg_locked(p, td); 1022 rucollect(&p->p_ru, &td->td_ru); 1023 PROC_STATUNLOCK(p); 1024 1025 TD_SET_STATE(td, TDS_INACTIVE); 1026 #ifdef WITNESS 1027 witness_thread_exit(td); 1028 #endif 1029 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 1030 sched_throw(td); 1031 panic("I'm a teapot!"); 1032 /* NOTREACHED */ 1033 } 1034 1035 /* 1036 * Do any thread specific cleanups that may be needed in wait() 1037 * called with Giant, proc and schedlock not held. 1038 */ 1039 void 1040 thread_wait(struct proc *p) 1041 { 1042 struct thread *td; 1043 1044 mtx_assert(&Giant, MA_NOTOWNED); 1045 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 1046 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 1047 td = FIRST_THREAD_IN_PROC(p); 1048 /* Lock the last thread so we spin until it exits cpu_throw(). */ 1049 thread_lock(td); 1050 thread_unlock(td); 1051 lock_profile_thread_exit(td); 1052 cpuset_rel(td->td_cpuset); 1053 td->td_cpuset = NULL; 1054 cpu_thread_clean(td); 1055 thread_cow_free(td); 1056 callout_drain(&td->td_slpcallout); 1057 thread_reap(); /* check for zombie threads etc. */ 1058 } 1059 1060 /* 1061 * Link a thread to a process. 1062 * set up anything that needs to be initialized for it to 1063 * be used by the process. 1064 */ 1065 void 1066 thread_link(struct thread *td, struct proc *p) 1067 { 1068 1069 /* 1070 * XXX This can't be enabled because it's called for proc0 before 1071 * its lock has been created. 1072 * PROC_LOCK_ASSERT(p, MA_OWNED); 1073 */ 1074 TD_SET_STATE(td, TDS_INACTIVE); 1075 td->td_proc = p; 1076 td->td_flags = TDF_INMEM; 1077 1078 LIST_INIT(&td->td_contested); 1079 LIST_INIT(&td->td_lprof[0]); 1080 LIST_INIT(&td->td_lprof[1]); 1081 #ifdef EPOCH_TRACE 1082 SLIST_INIT(&td->td_epochs); 1083 #endif 1084 sigqueue_init(&td->td_sigqueue, p); 1085 callout_init(&td->td_slpcallout, 1); 1086 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 1087 p->p_numthreads++; 1088 } 1089 1090 /* 1091 * Called from: 1092 * thread_exit() 1093 */ 1094 void 1095 thread_unlink(struct thread *td) 1096 { 1097 struct proc *p = td->td_proc; 1098 1099 PROC_LOCK_ASSERT(p, MA_OWNED); 1100 #ifdef EPOCH_TRACE 1101 MPASS(SLIST_EMPTY(&td->td_epochs)); 1102 #endif 1103 1104 TAILQ_REMOVE(&p->p_threads, td, td_plist); 1105 p->p_numthreads--; 1106 /* could clear a few other things here */ 1107 /* Must NOT clear links to proc! */ 1108 } 1109 1110 static int 1111 calc_remaining(struct proc *p, int mode) 1112 { 1113 int remaining; 1114 1115 PROC_LOCK_ASSERT(p, MA_OWNED); 1116 PROC_SLOCK_ASSERT(p, MA_OWNED); 1117 if (mode == SINGLE_EXIT) 1118 remaining = p->p_numthreads; 1119 else if (mode == SINGLE_BOUNDARY) 1120 remaining = p->p_numthreads - p->p_boundary_count; 1121 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 1122 remaining = p->p_numthreads - p->p_suspcount; 1123 else 1124 panic("calc_remaining: wrong mode %d", mode); 1125 return (remaining); 1126 } 1127 1128 static int 1129 remain_for_mode(int mode) 1130 { 1131 1132 return (mode == SINGLE_ALLPROC ? 0 : 1); 1133 } 1134 1135 static void 1136 weed_inhib(int mode, struct thread *td2, struct proc *p) 1137 { 1138 PROC_LOCK_ASSERT(p, MA_OWNED); 1139 PROC_SLOCK_ASSERT(p, MA_OWNED); 1140 THREAD_LOCK_ASSERT(td2, MA_OWNED); 1141 1142 /* 1143 * Since the thread lock is dropped by the scheduler we have 1144 * to retry to check for races. 1145 */ 1146 restart: 1147 switch (mode) { 1148 case SINGLE_EXIT: 1149 if (TD_IS_SUSPENDED(td2)) { 1150 thread_unsuspend_one(td2, p, true); 1151 thread_lock(td2); 1152 goto restart; 1153 } 1154 if (TD_CAN_ABORT(td2)) { 1155 sleepq_abort(td2, EINTR); 1156 return; 1157 } 1158 break; 1159 case SINGLE_BOUNDARY: 1160 case SINGLE_NO_EXIT: 1161 if (TD_IS_SUSPENDED(td2) && 1162 (td2->td_flags & TDF_BOUNDARY) == 0) { 1163 thread_unsuspend_one(td2, p, false); 1164 thread_lock(td2); 1165 goto restart; 1166 } 1167 if (TD_CAN_ABORT(td2)) { 1168 sleepq_abort(td2, ERESTART); 1169 return; 1170 } 1171 break; 1172 case SINGLE_ALLPROC: 1173 /* 1174 * ALLPROC suspend tries to avoid spurious EINTR for 1175 * threads sleeping interruptable, by suspending the 1176 * thread directly, similarly to sig_suspend_threads(). 1177 * Since such sleep is not neccessary performed at the user 1178 * boundary, TDF_ALLPROCSUSP is used to avoid immediate 1179 * un-suspend. 1180 */ 1181 if (TD_IS_SUSPENDED(td2) && 1182 (td2->td_flags & TDF_ALLPROCSUSP) == 0) { 1183 thread_unsuspend_one(td2, p, false); 1184 thread_lock(td2); 1185 goto restart; 1186 } 1187 if (TD_CAN_ABORT(td2)) { 1188 td2->td_flags |= TDF_ALLPROCSUSP; 1189 sleepq_abort(td2, ERESTART); 1190 return; 1191 } 1192 break; 1193 default: 1194 break; 1195 } 1196 thread_unlock(td2); 1197 } 1198 1199 /* 1200 * Enforce single-threading. 1201 * 1202 * Returns 1 if the caller must abort (another thread is waiting to 1203 * exit the process or similar). Process is locked! 1204 * Returns 0 when you are successfully the only thread running. 1205 * A process has successfully single threaded in the suspend mode when 1206 * There are no threads in user mode. Threads in the kernel must be 1207 * allowed to continue until they get to the user boundary. They may even 1208 * copy out their return values and data before suspending. They may however be 1209 * accelerated in reaching the user boundary as we will wake up 1210 * any sleeping threads that are interruptable. (PCATCH). 1211 */ 1212 int 1213 thread_single(struct proc *p, int mode) 1214 { 1215 struct thread *td; 1216 struct thread *td2; 1217 int remaining; 1218 1219 td = curthread; 1220 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1221 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1222 ("invalid mode %d", mode)); 1223 /* 1224 * If allowing non-ALLPROC singlethreading for non-curproc 1225 * callers, calc_remaining() and remain_for_mode() should be 1226 * adjusted to also account for td->td_proc != p. For now 1227 * this is not implemented because it is not used. 1228 */ 1229 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 1230 (mode != SINGLE_ALLPROC && td->td_proc == p), 1231 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 1232 mtx_assert(&Giant, MA_NOTOWNED); 1233 PROC_LOCK_ASSERT(p, MA_OWNED); 1234 1235 /* 1236 * Is someone already single threading? 1237 * Or may be singlethreading is not needed at all. 1238 */ 1239 if (mode == SINGLE_ALLPROC) { 1240 while ((p->p_flag & P_STOPPED_SINGLE) != 0) { 1241 if ((p->p_flag2 & P2_WEXIT) != 0) 1242 return (1); 1243 msleep(&p->p_flag, &p->p_mtx, PCATCH, "thrsgl", 0); 1244 } 1245 if ((p->p_flag & (P_STOPPED_SIG | P_TRACED)) != 0 || 1246 (p->p_flag2 & P2_WEXIT) != 0) 1247 return (1); 1248 } else if ((p->p_flag & P_HADTHREADS) == 0) 1249 return (0); 1250 if (p->p_singlethread != NULL && p->p_singlethread != td) 1251 return (1); 1252 1253 if (mode == SINGLE_EXIT) { 1254 p->p_flag |= P_SINGLE_EXIT; 1255 p->p_flag &= ~P_SINGLE_BOUNDARY; 1256 } else { 1257 p->p_flag &= ~P_SINGLE_EXIT; 1258 if (mode == SINGLE_BOUNDARY) 1259 p->p_flag |= P_SINGLE_BOUNDARY; 1260 else 1261 p->p_flag &= ~P_SINGLE_BOUNDARY; 1262 } 1263 if (mode == SINGLE_ALLPROC) 1264 p->p_flag |= P_TOTAL_STOP; 1265 p->p_flag |= P_STOPPED_SINGLE; 1266 PROC_SLOCK(p); 1267 p->p_singlethread = td; 1268 remaining = calc_remaining(p, mode); 1269 while (remaining != remain_for_mode(mode)) { 1270 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 1271 goto stopme; 1272 FOREACH_THREAD_IN_PROC(p, td2) { 1273 if (td2 == td) 1274 continue; 1275 thread_lock(td2); 1276 ast_sched_locked(td2, TDA_SUSPEND); 1277 if (TD_IS_INHIBITED(td2)) { 1278 weed_inhib(mode, td2, p); 1279 #ifdef SMP 1280 } else if (TD_IS_RUNNING(td2)) { 1281 forward_signal(td2); 1282 thread_unlock(td2); 1283 #endif 1284 } else 1285 thread_unlock(td2); 1286 } 1287 remaining = calc_remaining(p, mode); 1288 1289 /* 1290 * Maybe we suspended some threads.. was it enough? 1291 */ 1292 if (remaining == remain_for_mode(mode)) 1293 break; 1294 1295 stopme: 1296 /* 1297 * Wake us up when everyone else has suspended. 1298 * In the mean time we suspend as well. 1299 */ 1300 thread_suspend_switch(td, p); 1301 remaining = calc_remaining(p, mode); 1302 } 1303 if (mode == SINGLE_EXIT) { 1304 /* 1305 * Convert the process to an unthreaded process. The 1306 * SINGLE_EXIT is called by exit1() or execve(), in 1307 * both cases other threads must be retired. 1308 */ 1309 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 1310 p->p_singlethread = NULL; 1311 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 1312 1313 /* 1314 * Wait for any remaining threads to exit cpu_throw(). 1315 */ 1316 while (p->p_exitthreads != 0) { 1317 PROC_SUNLOCK(p); 1318 PROC_UNLOCK(p); 1319 sched_relinquish(td); 1320 PROC_LOCK(p); 1321 PROC_SLOCK(p); 1322 } 1323 } else if (mode == SINGLE_BOUNDARY) { 1324 /* 1325 * Wait until all suspended threads are removed from 1326 * the processors. The thread_suspend_check() 1327 * increments p_boundary_count while it is still 1328 * running, which makes it possible for the execve() 1329 * to destroy vmspace while our other threads are 1330 * still using the address space. 1331 * 1332 * We lock the thread, which is only allowed to 1333 * succeed after context switch code finished using 1334 * the address space. 1335 */ 1336 FOREACH_THREAD_IN_PROC(p, td2) { 1337 if (td2 == td) 1338 continue; 1339 thread_lock(td2); 1340 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 1341 ("td %p not on boundary", td2)); 1342 KASSERT(TD_IS_SUSPENDED(td2), 1343 ("td %p is not suspended", td2)); 1344 thread_unlock(td2); 1345 } 1346 } 1347 PROC_SUNLOCK(p); 1348 return (0); 1349 } 1350 1351 bool 1352 thread_suspend_check_needed(void) 1353 { 1354 struct proc *p; 1355 struct thread *td; 1356 1357 td = curthread; 1358 p = td->td_proc; 1359 PROC_LOCK_ASSERT(p, MA_OWNED); 1360 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 1361 (td->td_dbgflags & TDB_SUSPEND) != 0)); 1362 } 1363 1364 /* 1365 * Called in from locations that can safely check to see 1366 * whether we have to suspend or at least throttle for a 1367 * single-thread event (e.g. fork). 1368 * 1369 * Such locations include userret(). 1370 * If the "return_instead" argument is non zero, the thread must be able to 1371 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 1372 * 1373 * The 'return_instead' argument tells the function if it may do a 1374 * thread_exit() or suspend, or whether the caller must abort and back 1375 * out instead. 1376 * 1377 * If the thread that set the single_threading request has set the 1378 * P_SINGLE_EXIT bit in the process flags then this call will never return 1379 * if 'return_instead' is false, but will exit. 1380 * 1381 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 1382 *---------------+--------------------+--------------------- 1383 * 0 | returns 0 | returns 0 or 1 1384 * | when ST ends | immediately 1385 *---------------+--------------------+--------------------- 1386 * 1 | thread exits | returns 1 1387 * | | immediately 1388 * 0 = thread_exit() or suspension ok, 1389 * other = return error instead of stopping the thread. 1390 * 1391 * While a full suspension is under effect, even a single threading 1392 * thread would be suspended if it made this call (but it shouldn't). 1393 * This call should only be made from places where 1394 * thread_exit() would be safe as that may be the outcome unless 1395 * return_instead is set. 1396 */ 1397 int 1398 thread_suspend_check(int return_instead) 1399 { 1400 struct thread *td; 1401 struct proc *p; 1402 1403 td = curthread; 1404 p = td->td_proc; 1405 mtx_assert(&Giant, MA_NOTOWNED); 1406 PROC_LOCK_ASSERT(p, MA_OWNED); 1407 while (thread_suspend_check_needed()) { 1408 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1409 KASSERT(p->p_singlethread != NULL, 1410 ("singlethread not set")); 1411 /* 1412 * The only suspension in action is a 1413 * single-threading. Single threader need not stop. 1414 * It is safe to access p->p_singlethread unlocked 1415 * because it can only be set to our address by us. 1416 */ 1417 if (p->p_singlethread == td) 1418 return (0); /* Exempt from stopping. */ 1419 } 1420 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 1421 return (EINTR); 1422 1423 /* Should we goto user boundary if we didn't come from there? */ 1424 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1425 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 1426 return (ERESTART); 1427 1428 /* 1429 * Ignore suspend requests if they are deferred. 1430 */ 1431 if ((td->td_flags & TDF_SBDRY) != 0) { 1432 KASSERT(return_instead, 1433 ("TDF_SBDRY set for unsafe thread_suspend_check")); 1434 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 1435 (TDF_SEINTR | TDF_SERESTART), 1436 ("both TDF_SEINTR and TDF_SERESTART")); 1437 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 1438 } 1439 1440 /* 1441 * If the process is waiting for us to exit, 1442 * this thread should just suicide. 1443 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 1444 */ 1445 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 1446 PROC_UNLOCK(p); 1447 1448 /* 1449 * Allow Linux emulation layer to do some work 1450 * before thread suicide. 1451 */ 1452 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 1453 (p->p_sysent->sv_thread_detach)(td); 1454 umtx_thread_exit(td); 1455 kern_thr_exit(td); 1456 panic("stopped thread did not exit"); 1457 } 1458 1459 PROC_SLOCK(p); 1460 thread_stopped(p); 1461 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1462 if (p->p_numthreads == p->p_suspcount + 1) { 1463 thread_lock(p->p_singlethread); 1464 thread_unsuspend_one(p->p_singlethread, p, 1465 false); 1466 } 1467 } 1468 PROC_UNLOCK(p); 1469 thread_lock(td); 1470 /* 1471 * When a thread suspends, it just 1472 * gets taken off all queues. 1473 */ 1474 thread_suspend_one(td); 1475 if (return_instead == 0) { 1476 p->p_boundary_count++; 1477 td->td_flags |= TDF_BOUNDARY; 1478 } 1479 PROC_SUNLOCK(p); 1480 mi_switch(SW_INVOL | SWT_SUSPEND); 1481 PROC_LOCK(p); 1482 } 1483 return (0); 1484 } 1485 1486 /* 1487 * Check for possible stops and suspensions while executing a 1488 * casueword or similar transiently failing operation. 1489 * 1490 * The sleep argument controls whether the function can handle a stop 1491 * request itself or it should return ERESTART and the request is 1492 * proceed at the kernel/user boundary in ast. 1493 * 1494 * Typically, when retrying due to casueword(9) failure (rv == 1), we 1495 * should handle the stop requests there, with exception of cases when 1496 * the thread owns a kernel resource, for instance busied the umtx 1497 * key, or when functions return immediately if thread_check_susp() 1498 * returned non-zero. On the other hand, retrying the whole lock 1499 * operation, we better not stop there but delegate the handling to 1500 * ast. 1501 * 1502 * If the request is for thread termination P_SINGLE_EXIT, we cannot 1503 * handle it at all, and simply return EINTR. 1504 */ 1505 int 1506 thread_check_susp(struct thread *td, bool sleep) 1507 { 1508 struct proc *p; 1509 int error; 1510 1511 /* 1512 * The check for TDA_SUSPEND is racy, but it is enough to 1513 * eventually break the lockstep loop. 1514 */ 1515 if (!td_ast_pending(td, TDA_SUSPEND)) 1516 return (0); 1517 error = 0; 1518 p = td->td_proc; 1519 PROC_LOCK(p); 1520 if (p->p_flag & P_SINGLE_EXIT) 1521 error = EINTR; 1522 else if (P_SHOULDSTOP(p) || 1523 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) 1524 error = sleep ? thread_suspend_check(0) : ERESTART; 1525 PROC_UNLOCK(p); 1526 return (error); 1527 } 1528 1529 void 1530 thread_suspend_switch(struct thread *td, struct proc *p) 1531 { 1532 1533 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1534 PROC_LOCK_ASSERT(p, MA_OWNED); 1535 PROC_SLOCK_ASSERT(p, MA_OWNED); 1536 /* 1537 * We implement thread_suspend_one in stages here to avoid 1538 * dropping the proc lock while the thread lock is owned. 1539 */ 1540 if (p == td->td_proc) { 1541 thread_stopped(p); 1542 p->p_suspcount++; 1543 } 1544 PROC_UNLOCK(p); 1545 thread_lock(td); 1546 ast_unsched_locked(td, TDA_SUSPEND); 1547 TD_SET_SUSPENDED(td); 1548 sched_sleep(td, 0); 1549 PROC_SUNLOCK(p); 1550 DROP_GIANT(); 1551 mi_switch(SW_VOL | SWT_SUSPEND); 1552 PICKUP_GIANT(); 1553 PROC_LOCK(p); 1554 PROC_SLOCK(p); 1555 } 1556 1557 void 1558 thread_suspend_one(struct thread *td) 1559 { 1560 struct proc *p; 1561 1562 p = td->td_proc; 1563 PROC_SLOCK_ASSERT(p, MA_OWNED); 1564 THREAD_LOCK_ASSERT(td, MA_OWNED); 1565 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1566 p->p_suspcount++; 1567 ast_unsched_locked(td, TDA_SUSPEND); 1568 TD_SET_SUSPENDED(td); 1569 sched_sleep(td, 0); 1570 } 1571 1572 static void 1573 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1574 { 1575 1576 THREAD_LOCK_ASSERT(td, MA_OWNED); 1577 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1578 TD_CLR_SUSPENDED(td); 1579 td->td_flags &= ~TDF_ALLPROCSUSP; 1580 if (td->td_proc == p) { 1581 PROC_SLOCK_ASSERT(p, MA_OWNED); 1582 p->p_suspcount--; 1583 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1584 td->td_flags &= ~TDF_BOUNDARY; 1585 p->p_boundary_count--; 1586 } 1587 } 1588 setrunnable(td, 0); 1589 } 1590 1591 void 1592 thread_run_flash(struct thread *td) 1593 { 1594 struct proc *p; 1595 1596 p = td->td_proc; 1597 PROC_LOCK_ASSERT(p, MA_OWNED); 1598 1599 if (TD_ON_SLEEPQ(td)) 1600 sleepq_remove_nested(td); 1601 else 1602 thread_lock(td); 1603 1604 THREAD_LOCK_ASSERT(td, MA_OWNED); 1605 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1606 1607 TD_CLR_SUSPENDED(td); 1608 PROC_SLOCK(p); 1609 MPASS(p->p_suspcount > 0); 1610 p->p_suspcount--; 1611 PROC_SUNLOCK(p); 1612 setrunnable(td, 0); 1613 } 1614 1615 /* 1616 * Allow all threads blocked by single threading to continue running. 1617 */ 1618 void 1619 thread_unsuspend(struct proc *p) 1620 { 1621 struct thread *td; 1622 1623 PROC_LOCK_ASSERT(p, MA_OWNED); 1624 PROC_SLOCK_ASSERT(p, MA_OWNED); 1625 if (!P_SHOULDSTOP(p)) { 1626 FOREACH_THREAD_IN_PROC(p, td) { 1627 thread_lock(td); 1628 if (TD_IS_SUSPENDED(td)) 1629 thread_unsuspend_one(td, p, true); 1630 else 1631 thread_unlock(td); 1632 } 1633 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1634 p->p_numthreads == p->p_suspcount) { 1635 /* 1636 * Stopping everything also did the job for the single 1637 * threading request. Now we've downgraded to single-threaded, 1638 * let it continue. 1639 */ 1640 if (p->p_singlethread->td_proc == p) { 1641 thread_lock(p->p_singlethread); 1642 thread_unsuspend_one(p->p_singlethread, p, false); 1643 } 1644 } 1645 } 1646 1647 /* 1648 * End the single threading mode.. 1649 */ 1650 void 1651 thread_single_end(struct proc *p, int mode) 1652 { 1653 struct thread *td; 1654 1655 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1656 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1657 ("invalid mode %d", mode)); 1658 PROC_LOCK_ASSERT(p, MA_OWNED); 1659 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1660 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1661 ("mode %d does not match P_TOTAL_STOP", mode)); 1662 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1663 ("thread_single_end from other thread %p %p", 1664 curthread, p->p_singlethread)); 1665 KASSERT(mode != SINGLE_BOUNDARY || 1666 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1667 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1668 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1669 P_TOTAL_STOP); 1670 PROC_SLOCK(p); 1671 p->p_singlethread = NULL; 1672 1673 /* 1674 * If there are other threads they may now run, 1675 * unless of course there is a blanket 'stop order' 1676 * on the process. The single threader must be allowed 1677 * to continue however as this is a bad place to stop. 1678 */ 1679 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1680 FOREACH_THREAD_IN_PROC(p, td) { 1681 thread_lock(td); 1682 if (TD_IS_SUSPENDED(td)) 1683 thread_unsuspend_one(td, p, true); 1684 else 1685 thread_unlock(td); 1686 } 1687 } 1688 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1689 ("inconsistent boundary count %d", p->p_boundary_count)); 1690 PROC_SUNLOCK(p); 1691 wakeup(&p->p_flag); 1692 } 1693 1694 /* 1695 * Locate a thread by number and return with proc lock held. 1696 * 1697 * thread exit establishes proc -> tidhash lock ordering, but lookup 1698 * takes tidhash first and needs to return locked proc. 1699 * 1700 * The problem is worked around by relying on type-safety of both 1701 * structures and doing the work in 2 steps: 1702 * - tidhash-locked lookup which saves both thread and proc pointers 1703 * - proc-locked verification that the found thread still matches 1704 */ 1705 static bool 1706 tdfind_hash(lwpid_t tid, pid_t pid, struct proc **pp, struct thread **tdp) 1707 { 1708 #define RUN_THRESH 16 1709 struct proc *p; 1710 struct thread *td; 1711 int run; 1712 bool locked; 1713 1714 run = 0; 1715 rw_rlock(TIDHASHLOCK(tid)); 1716 locked = true; 1717 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1718 if (td->td_tid != tid) { 1719 run++; 1720 continue; 1721 } 1722 p = td->td_proc; 1723 if (pid != -1 && p->p_pid != pid) { 1724 td = NULL; 1725 break; 1726 } 1727 if (run > RUN_THRESH) { 1728 if (rw_try_upgrade(TIDHASHLOCK(tid))) { 1729 LIST_REMOVE(td, td_hash); 1730 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1731 td, td_hash); 1732 rw_wunlock(TIDHASHLOCK(tid)); 1733 locked = false; 1734 break; 1735 } 1736 } 1737 break; 1738 } 1739 if (locked) 1740 rw_runlock(TIDHASHLOCK(tid)); 1741 if (td == NULL) 1742 return (false); 1743 *pp = p; 1744 *tdp = td; 1745 return (true); 1746 } 1747 1748 struct thread * 1749 tdfind(lwpid_t tid, pid_t pid) 1750 { 1751 struct proc *p; 1752 struct thread *td; 1753 1754 td = curthread; 1755 if (td->td_tid == tid) { 1756 if (pid != -1 && td->td_proc->p_pid != pid) 1757 return (NULL); 1758 PROC_LOCK(td->td_proc); 1759 return (td); 1760 } 1761 1762 for (;;) { 1763 if (!tdfind_hash(tid, pid, &p, &td)) 1764 return (NULL); 1765 PROC_LOCK(p); 1766 if (td->td_tid != tid) { 1767 PROC_UNLOCK(p); 1768 continue; 1769 } 1770 if (td->td_proc != p) { 1771 PROC_UNLOCK(p); 1772 continue; 1773 } 1774 if (p->p_state == PRS_NEW) { 1775 PROC_UNLOCK(p); 1776 return (NULL); 1777 } 1778 return (td); 1779 } 1780 } 1781 1782 void 1783 tidhash_add(struct thread *td) 1784 { 1785 rw_wlock(TIDHASHLOCK(td->td_tid)); 1786 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1787 rw_wunlock(TIDHASHLOCK(td->td_tid)); 1788 } 1789 1790 void 1791 tidhash_remove(struct thread *td) 1792 { 1793 1794 rw_wlock(TIDHASHLOCK(td->td_tid)); 1795 LIST_REMOVE(td, td_hash); 1796 rw_wunlock(TIDHASHLOCK(td->td_tid)); 1797 } 1798