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/cdefs.h> 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/lock.h> 39 #include <sys/msan.h> 40 #include <sys/mutex.h> 41 #include <sys/proc.h> 42 #include <sys/bitstring.h> 43 #include <sys/epoch.h> 44 #include <sys/rangelock.h> 45 #include <sys/resourcevar.h> 46 #include <sys/sdt.h> 47 #include <sys/smp.h> 48 #include <sys/sched.h> 49 #include <sys/sleepqueue.h> 50 #include <sys/selinfo.h> 51 #include <sys/syscallsubr.h> 52 #include <sys/dtrace_bsd.h> 53 #include <sys/sysent.h> 54 #include <sys/turnstile.h> 55 #include <sys/taskqueue.h> 56 #include <sys/ktr.h> 57 #include <sys/rwlock.h> 58 #include <sys/umtxvar.h> 59 #include <sys/vmmeter.h> 60 #include <sys/cpuset.h> 61 #ifdef HWPMC_HOOKS 62 #include <sys/pmckern.h> 63 #endif 64 #include <sys/priv.h> 65 66 #include <security/audit/audit.h> 67 68 #include <vm/pmap.h> 69 #include <vm/vm.h> 70 #include <vm/vm_extern.h> 71 #include <vm/uma.h> 72 #include <vm/vm_phys.h> 73 #include <sys/eventhandler.h> 74 75 /* 76 * Asserts below verify the stability of struct thread and struct proc 77 * layout, as exposed by KBI to modules. On head, the KBI is allowed 78 * to drift, change to the structures must be accompanied by the 79 * assert update. 80 * 81 * On the stable branches after KBI freeze, conditions must not be 82 * violated. Typically new fields are moved to the end of the 83 * structures. 84 */ 85 #ifdef __amd64__ 86 _Static_assert(offsetof(struct thread, td_flags) == 0x108, 87 "struct thread KBI td_flags"); 88 _Static_assert(offsetof(struct thread, td_pflags) == 0x114, 89 "struct thread KBI td_pflags"); 90 _Static_assert(offsetof(struct thread, td_frame) == 0x4b8, 91 "struct thread KBI td_frame"); 92 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6c0, 93 "struct thread KBI td_emuldata"); 94 _Static_assert(offsetof(struct proc, p_flag) == 0xb8, 95 "struct proc KBI p_flag"); 96 _Static_assert(offsetof(struct proc, p_pid) == 0xc4, 97 "struct proc KBI p_pid"); 98 _Static_assert(offsetof(struct proc, p_filemon) == 0x3c8, 99 "struct proc KBI p_filemon"); 100 _Static_assert(offsetof(struct proc, p_comm) == 0x3e0, 101 "struct proc KBI p_comm"); 102 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4d0, 103 "struct proc KBI p_emuldata"); 104 #endif 105 #ifdef __i386__ 106 _Static_assert(offsetof(struct thread, td_flags) == 0x9c, 107 "struct thread KBI td_flags"); 108 _Static_assert(offsetof(struct thread, td_pflags) == 0xa8, 109 "struct thread KBI td_pflags"); 110 _Static_assert(offsetof(struct thread, td_frame) == 0x318, 111 "struct thread KBI td_frame"); 112 _Static_assert(offsetof(struct thread, td_emuldata) == 0x35c, 113 "struct thread KBI td_emuldata"); 114 _Static_assert(offsetof(struct proc, p_flag) == 0x6c, 115 "struct proc KBI p_flag"); 116 _Static_assert(offsetof(struct proc, p_pid) == 0x78, 117 "struct proc KBI p_pid"); 118 _Static_assert(offsetof(struct proc, p_filemon) == 0x270, 119 "struct proc KBI p_filemon"); 120 _Static_assert(offsetof(struct proc, p_comm) == 0x284, 121 "struct proc KBI p_comm"); 122 _Static_assert(offsetof(struct proc, p_emuldata) == 0x318, 123 "struct proc KBI p_emuldata"); 124 #endif 125 126 SDT_PROVIDER_DECLARE(proc); 127 SDT_PROBE_DEFINE(proc, , , lwp__exit); 128 129 /* 130 * thread related storage. 131 */ 132 static uma_zone_t thread_zone; 133 134 struct thread_domain_data { 135 struct thread *tdd_zombies; 136 int tdd_reapticks; 137 } __aligned(CACHE_LINE_SIZE); 138 139 static struct thread_domain_data thread_domain_data[MAXMEMDOM]; 140 141 static struct task thread_reap_task; 142 static struct callout thread_reap_callout; 143 144 static void thread_zombie(struct thread *); 145 static void thread_reap(void); 146 static void thread_reap_all(void); 147 static void thread_reap_task_cb(void *, int); 148 static void thread_reap_callout_cb(void *); 149 static int thread_unsuspend_one(struct thread *td, struct proc *p, 150 bool boundary); 151 static void thread_free_batched(struct thread *td); 152 153 static __exclusive_cache_line struct mtx tid_lock; 154 static bitstr_t *tid_bitmap; 155 156 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 157 158 static int maxthread; 159 SYSCTL_INT(_kern, OID_AUTO, maxthread, CTLFLAG_RDTUN, 160 &maxthread, 0, "Maximum number of threads"); 161 162 static __exclusive_cache_line int nthreads; 163 164 static LIST_HEAD(tidhashhead, thread) *tidhashtbl; 165 static u_long tidhash; 166 static u_long tidhashlock; 167 static struct rwlock *tidhashtbl_lock; 168 #define TIDHASH(tid) (&tidhashtbl[(tid) & tidhash]) 169 #define TIDHASHLOCK(tid) (&tidhashtbl_lock[(tid) & tidhashlock]) 170 171 EVENTHANDLER_LIST_DEFINE(thread_ctor); 172 EVENTHANDLER_LIST_DEFINE(thread_dtor); 173 EVENTHANDLER_LIST_DEFINE(thread_init); 174 EVENTHANDLER_LIST_DEFINE(thread_fini); 175 176 static bool 177 thread_count_inc_try(void) 178 { 179 int nthreads_new; 180 181 nthreads_new = atomic_fetchadd_int(&nthreads, 1) + 1; 182 if (nthreads_new >= maxthread - 100) { 183 if (priv_check_cred(curthread->td_ucred, PRIV_MAXPROC) != 0 || 184 nthreads_new >= maxthread) { 185 atomic_subtract_int(&nthreads, 1); 186 return (false); 187 } 188 } 189 return (true); 190 } 191 192 static bool 193 thread_count_inc(void) 194 { 195 static struct timeval lastfail; 196 static int curfail; 197 198 thread_reap(); 199 if (thread_count_inc_try()) { 200 return (true); 201 } 202 203 thread_reap_all(); 204 if (thread_count_inc_try()) { 205 return (true); 206 } 207 208 if (ppsratecheck(&lastfail, &curfail, 1)) { 209 printf("maxthread limit exceeded by uid %u " 210 "(pid %d); consider increasing kern.maxthread\n", 211 curthread->td_ucred->cr_ruid, curproc->p_pid); 212 } 213 return (false); 214 } 215 216 static void 217 thread_count_sub(int n) 218 { 219 220 atomic_subtract_int(&nthreads, n); 221 } 222 223 static void 224 thread_count_dec(void) 225 { 226 227 thread_count_sub(1); 228 } 229 230 static lwpid_t 231 tid_alloc(void) 232 { 233 static lwpid_t trytid; 234 lwpid_t tid; 235 236 mtx_lock(&tid_lock); 237 /* 238 * It is an invariant that the bitmap is big enough to hold maxthread 239 * IDs. If we got to this point there has to be at least one free. 240 */ 241 if (trytid >= maxthread) 242 trytid = 0; 243 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 244 if (tid == -1) { 245 KASSERT(trytid != 0, ("unexpectedly ran out of IDs")); 246 trytid = 0; 247 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 248 KASSERT(tid != -1, ("unexpectedly ran out of IDs")); 249 } 250 bit_set(tid_bitmap, tid); 251 trytid = tid + 1; 252 mtx_unlock(&tid_lock); 253 return (tid + NO_PID); 254 } 255 256 static void 257 tid_free_locked(lwpid_t rtid) 258 { 259 lwpid_t tid; 260 261 mtx_assert(&tid_lock, MA_OWNED); 262 KASSERT(rtid >= NO_PID, 263 ("%s: invalid tid %d\n", __func__, rtid)); 264 tid = rtid - NO_PID; 265 KASSERT(bit_test(tid_bitmap, tid) != 0, 266 ("thread ID %d not allocated\n", rtid)); 267 bit_clear(tid_bitmap, tid); 268 } 269 270 static void 271 tid_free(lwpid_t rtid) 272 { 273 274 mtx_lock(&tid_lock); 275 tid_free_locked(rtid); 276 mtx_unlock(&tid_lock); 277 } 278 279 static void 280 tid_free_batch(lwpid_t *batch, int n) 281 { 282 int i; 283 284 mtx_lock(&tid_lock); 285 for (i = 0; i < n; i++) { 286 tid_free_locked(batch[i]); 287 } 288 mtx_unlock(&tid_lock); 289 } 290 291 /* 292 * Batching for thread reapping. 293 */ 294 struct tidbatch { 295 lwpid_t tab[16]; 296 int n; 297 }; 298 299 static void 300 tidbatch_prep(struct tidbatch *tb) 301 { 302 303 tb->n = 0; 304 } 305 306 static void 307 tidbatch_add(struct tidbatch *tb, struct thread *td) 308 { 309 310 KASSERT(tb->n < nitems(tb->tab), 311 ("%s: count too high %d", __func__, tb->n)); 312 tb->tab[tb->n] = td->td_tid; 313 tb->n++; 314 } 315 316 static void 317 tidbatch_process(struct tidbatch *tb) 318 { 319 320 KASSERT(tb->n <= nitems(tb->tab), 321 ("%s: count too high %d", __func__, tb->n)); 322 if (tb->n == nitems(tb->tab)) { 323 tid_free_batch(tb->tab, tb->n); 324 tb->n = 0; 325 } 326 } 327 328 static void 329 tidbatch_final(struct tidbatch *tb) 330 { 331 332 KASSERT(tb->n <= nitems(tb->tab), 333 ("%s: count too high %d", __func__, tb->n)); 334 if (tb->n != 0) { 335 tid_free_batch(tb->tab, tb->n); 336 } 337 } 338 339 /* 340 * Batching thread count free, for consistency 341 */ 342 struct tdcountbatch { 343 int n; 344 }; 345 346 static void 347 tdcountbatch_prep(struct tdcountbatch *tb) 348 { 349 350 tb->n = 0; 351 } 352 353 static void 354 tdcountbatch_add(struct tdcountbatch *tb, struct thread *td __unused) 355 { 356 357 tb->n++; 358 } 359 360 static void 361 tdcountbatch_process(struct tdcountbatch *tb) 362 { 363 364 if (tb->n == 32) { 365 thread_count_sub(tb->n); 366 tb->n = 0; 367 } 368 } 369 370 static void 371 tdcountbatch_final(struct tdcountbatch *tb) 372 { 373 374 if (tb->n != 0) { 375 thread_count_sub(tb->n); 376 } 377 } 378 379 /* 380 * Prepare a thread for use. 381 */ 382 static int 383 thread_ctor(void *mem, int size, void *arg, int flags) 384 { 385 struct thread *td; 386 387 td = (struct thread *)mem; 388 TD_SET_STATE(td, TDS_INACTIVE); 389 td->td_lastcpu = td->td_oncpu = NOCPU; 390 391 /* 392 * Note that td_critnest begins life as 1 because the thread is not 393 * running and is thereby implicitly waiting to be on the receiving 394 * end of a context switch. 395 */ 396 td->td_critnest = 1; 397 td->td_lend_user_pri = PRI_MAX; 398 #ifdef AUDIT 399 audit_thread_alloc(td); 400 #endif 401 #ifdef KDTRACE_HOOKS 402 kdtrace_thread_ctor(td); 403 #endif 404 umtx_thread_alloc(td); 405 MPASS(td->td_sel == NULL); 406 return (0); 407 } 408 409 /* 410 * Reclaim a thread after use. 411 */ 412 static void 413 thread_dtor(void *mem, int size, void *arg) 414 { 415 struct thread *td; 416 417 td = (struct thread *)mem; 418 419 #ifdef INVARIANTS 420 /* Verify that this thread is in a safe state to free. */ 421 switch (TD_GET_STATE(td)) { 422 case TDS_INHIBITED: 423 case TDS_RUNNING: 424 case TDS_CAN_RUN: 425 case TDS_RUNQ: 426 /* 427 * We must never unlink a thread that is in one of 428 * these states, because it is currently active. 429 */ 430 panic("bad state for thread unlinking"); 431 /* NOTREACHED */ 432 case TDS_INACTIVE: 433 break; 434 default: 435 panic("bad thread state"); 436 /* NOTREACHED */ 437 } 438 #endif 439 #ifdef AUDIT 440 audit_thread_free(td); 441 #endif 442 #ifdef KDTRACE_HOOKS 443 kdtrace_thread_dtor(td); 444 #endif 445 /* Free all OSD associated to this thread. */ 446 osd_thread_exit(td); 447 ast_kclear(td); 448 seltdfini(td); 449 } 450 451 /* 452 * Initialize type-stable parts of a thread (when newly created). 453 */ 454 static int 455 thread_init(void *mem, int size, int flags) 456 { 457 struct thread *td; 458 459 td = (struct thread *)mem; 460 461 td->td_allocdomain = vm_phys_domain(vtophys(td)); 462 td->td_sleepqueue = sleepq_alloc(); 463 td->td_turnstile = turnstile_alloc(); 464 td->td_rlqe = NULL; 465 EVENTHANDLER_DIRECT_INVOKE(thread_init, td); 466 umtx_thread_init(td); 467 td->td_kstack = 0; 468 td->td_sel = NULL; 469 return (0); 470 } 471 472 /* 473 * Tear down type-stable parts of a thread (just before being discarded). 474 */ 475 static void 476 thread_fini(void *mem, int size) 477 { 478 struct thread *td; 479 480 td = (struct thread *)mem; 481 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td); 482 rlqentry_free(td->td_rlqe); 483 turnstile_free(td->td_turnstile); 484 sleepq_free(td->td_sleepqueue); 485 umtx_thread_fini(td); 486 MPASS(td->td_sel == NULL); 487 } 488 489 /* 490 * For a newly created process, 491 * link up all the structures and its initial threads etc. 492 * called from: 493 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 494 * proc_dtor() (should go away) 495 * proc_init() 496 */ 497 void 498 proc_linkup0(struct proc *p, struct thread *td) 499 { 500 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 501 proc_linkup(p, td); 502 } 503 504 void 505 proc_linkup(struct proc *p, struct thread *td) 506 { 507 508 sigqueue_init(&p->p_sigqueue, p); 509 p->p_ksi = ksiginfo_alloc(M_WAITOK); 510 if (p->p_ksi != NULL) { 511 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 512 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 513 } 514 LIST_INIT(&p->p_mqnotifier); 515 p->p_numthreads = 0; 516 thread_link(td, p); 517 } 518 519 static void 520 ast_suspend(struct thread *td, int tda __unused) 521 { 522 struct proc *p; 523 524 p = td->td_proc; 525 /* 526 * We need to check to see if we have to exit or wait due to a 527 * single threading requirement or some other STOP condition. 528 */ 529 PROC_LOCK(p); 530 thread_suspend_check(0); 531 PROC_UNLOCK(p); 532 } 533 534 extern int max_threads_per_proc; 535 536 /* 537 * Initialize global thread allocation resources. 538 */ 539 void 540 threadinit(void) 541 { 542 u_long i; 543 lwpid_t tid0; 544 545 /* 546 * Place an upper limit on threads which can be allocated. 547 * 548 * Note that other factors may make the de facto limit much lower. 549 * 550 * Platform limits are somewhat arbitrary but deemed "more than good 551 * enough" for the foreseable future. 552 */ 553 if (maxthread == 0) { 554 #ifdef _LP64 555 maxthread = MIN(maxproc * max_threads_per_proc, 1000000); 556 #else 557 maxthread = MIN(maxproc * max_threads_per_proc, 100000); 558 #endif 559 } 560 561 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 562 tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK); 563 /* 564 * Handle thread0. 565 */ 566 thread_count_inc(); 567 tid0 = tid_alloc(); 568 if (tid0 != THREAD0_TID) 569 panic("tid0 %d != %d\n", tid0, THREAD0_TID); 570 571 /* 572 * Thread structures are specially aligned so that (at least) the 573 * 5 lower bits of a pointer to 'struct thead' must be 0. These bits 574 * are used by synchronization primitives to store flags in pointers to 575 * such structures. 576 */ 577 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 578 thread_ctor, thread_dtor, thread_init, thread_fini, 579 UMA_ALIGN_CACHE_AND_MASK(32 - 1), UMA_ZONE_NOFREE); 580 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 581 tidhashlock = (tidhash + 1) / 64; 582 if (tidhashlock > 0) 583 tidhashlock--; 584 tidhashtbl_lock = malloc(sizeof(*tidhashtbl_lock) * (tidhashlock + 1), 585 M_TIDHASH, M_WAITOK | M_ZERO); 586 for (i = 0; i < tidhashlock + 1; i++) 587 rw_init(&tidhashtbl_lock[i], "tidhash"); 588 589 TASK_INIT(&thread_reap_task, 0, thread_reap_task_cb, NULL); 590 callout_init(&thread_reap_callout, 1); 591 callout_reset(&thread_reap_callout, 5 * hz, 592 thread_reap_callout_cb, NULL); 593 ast_register(TDA_SUSPEND, ASTR_ASTF_REQUIRED, 0, ast_suspend); 594 } 595 596 /* 597 * Place an unused thread on the zombie list. 598 */ 599 void 600 thread_zombie(struct thread *td) 601 { 602 struct thread_domain_data *tdd; 603 struct thread *ztd; 604 605 tdd = &thread_domain_data[td->td_allocdomain]; 606 ztd = atomic_load_ptr(&tdd->tdd_zombies); 607 for (;;) { 608 td->td_zombie = ztd; 609 if (atomic_fcmpset_rel_ptr((uintptr_t *)&tdd->tdd_zombies, 610 (uintptr_t *)&ztd, (uintptr_t)td)) 611 break; 612 continue; 613 } 614 } 615 616 /* 617 * Release a thread that has exited after cpu_throw(). 618 */ 619 void 620 thread_stash(struct thread *td) 621 { 622 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 623 thread_zombie(td); 624 } 625 626 /* 627 * Reap zombies from passed domain. 628 */ 629 static void 630 thread_reap_domain(struct thread_domain_data *tdd) 631 { 632 struct thread *itd, *ntd; 633 struct tidbatch tidbatch; 634 struct credbatch credbatch; 635 struct limbatch limbatch; 636 struct tdcountbatch tdcountbatch; 637 638 /* 639 * Reading upfront is pessimal if followed by concurrent atomic_swap, 640 * but most of the time the list is empty. 641 */ 642 if (tdd->tdd_zombies == NULL) 643 return; 644 645 itd = (struct thread *)atomic_swap_ptr((uintptr_t *)&tdd->tdd_zombies, 646 (uintptr_t)NULL); 647 if (itd == NULL) 648 return; 649 650 /* 651 * Multiple CPUs can get here, the race is fine as ticks is only 652 * advisory. 653 */ 654 tdd->tdd_reapticks = ticks; 655 656 tidbatch_prep(&tidbatch); 657 credbatch_prep(&credbatch); 658 limbatch_prep(&limbatch); 659 tdcountbatch_prep(&tdcountbatch); 660 661 while (itd != NULL) { 662 ntd = itd->td_zombie; 663 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, itd); 664 665 tidbatch_add(&tidbatch, itd); 666 credbatch_add(&credbatch, itd); 667 limbatch_add(&limbatch, itd); 668 tdcountbatch_add(&tdcountbatch, itd); 669 670 thread_free_batched(itd); 671 672 tidbatch_process(&tidbatch); 673 credbatch_process(&credbatch); 674 limbatch_process(&limbatch); 675 tdcountbatch_process(&tdcountbatch); 676 677 itd = ntd; 678 } 679 680 tidbatch_final(&tidbatch); 681 credbatch_final(&credbatch); 682 limbatch_final(&limbatch); 683 tdcountbatch_final(&tdcountbatch); 684 } 685 686 /* 687 * Reap zombies from all domains. 688 */ 689 static void 690 thread_reap_all(void) 691 { 692 struct thread_domain_data *tdd; 693 int i, domain; 694 695 domain = PCPU_GET(domain); 696 for (i = 0; i < vm_ndomains; i++) { 697 tdd = &thread_domain_data[(i + domain) % vm_ndomains]; 698 thread_reap_domain(tdd); 699 } 700 } 701 702 /* 703 * Reap zombies from local domain. 704 */ 705 static void 706 thread_reap(void) 707 { 708 struct thread_domain_data *tdd; 709 int domain; 710 711 domain = PCPU_GET(domain); 712 tdd = &thread_domain_data[domain]; 713 714 thread_reap_domain(tdd); 715 } 716 717 static void 718 thread_reap_task_cb(void *arg __unused, int pending __unused) 719 { 720 721 thread_reap_all(); 722 } 723 724 static void 725 thread_reap_callout_cb(void *arg __unused) 726 { 727 struct thread_domain_data *tdd; 728 int i, cticks, lticks; 729 bool wantreap; 730 731 wantreap = false; 732 cticks = atomic_load_int(&ticks); 733 for (i = 0; i < vm_ndomains; i++) { 734 tdd = &thread_domain_data[i]; 735 lticks = tdd->tdd_reapticks; 736 if (tdd->tdd_zombies != NULL && 737 (u_int)(cticks - lticks) > 5 * hz) { 738 wantreap = true; 739 break; 740 } 741 } 742 743 if (wantreap) 744 taskqueue_enqueue(taskqueue_thread, &thread_reap_task); 745 callout_reset(&thread_reap_callout, 5 * hz, 746 thread_reap_callout_cb, NULL); 747 } 748 749 /* 750 * Calling this function guarantees that any thread that exited before 751 * the call is reaped when the function returns. By 'exited' we mean 752 * a thread removed from the process linkage with thread_unlink(). 753 * Practically this means that caller must lock/unlock corresponding 754 * process lock before the call, to synchronize with thread_exit(). 755 */ 756 void 757 thread_reap_barrier(void) 758 { 759 struct task *t; 760 761 /* 762 * First do context switches to each CPU to ensure that all 763 * PCPU pc_deadthreads are moved to zombie list. 764 */ 765 quiesce_all_cpus("", PDROP); 766 767 /* 768 * Second, fire the task in the same thread as normal 769 * thread_reap() is done, to serialize reaping. 770 */ 771 t = malloc(sizeof(*t), M_TEMP, M_WAITOK); 772 TASK_INIT(t, 0, thread_reap_task_cb, t); 773 taskqueue_enqueue(taskqueue_thread, t); 774 taskqueue_drain(taskqueue_thread, t); 775 free(t, M_TEMP); 776 } 777 778 /* 779 * Allocate a thread. 780 */ 781 struct thread * 782 thread_alloc(int pages) 783 { 784 struct thread *td; 785 lwpid_t tid; 786 787 if (!thread_count_inc()) { 788 return (NULL); 789 } 790 791 tid = tid_alloc(); 792 td = uma_zalloc(thread_zone, M_WAITOK); 793 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 794 if (!vm_thread_new(td, pages)) { 795 uma_zfree(thread_zone, td); 796 tid_free(tid); 797 thread_count_dec(); 798 return (NULL); 799 } 800 td->td_tid = tid; 801 bzero(&td->td_sa.args, sizeof(td->td_sa.args)); 802 kmsan_thread_alloc(td); 803 cpu_thread_alloc(td); 804 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); 805 return (td); 806 } 807 808 int 809 thread_alloc_stack(struct thread *td, int pages) 810 { 811 812 KASSERT(td->td_kstack == 0, 813 ("thread_alloc_stack called on a thread with kstack")); 814 if (!vm_thread_new(td, pages)) 815 return (0); 816 cpu_thread_alloc(td); 817 return (1); 818 } 819 820 /* 821 * Deallocate a thread. 822 */ 823 static void 824 thread_free_batched(struct thread *td) 825 { 826 827 lock_profile_thread_exit(td); 828 if (td->td_cpuset) 829 cpuset_rel(td->td_cpuset); 830 td->td_cpuset = NULL; 831 cpu_thread_free(td); 832 if (td->td_kstack != 0) 833 vm_thread_dispose(td); 834 callout_drain(&td->td_slpcallout); 835 /* 836 * Freeing handled by the caller. 837 */ 838 td->td_tid = -1; 839 kmsan_thread_free(td); 840 uma_zfree(thread_zone, td); 841 } 842 843 void 844 thread_free(struct thread *td) 845 { 846 lwpid_t tid; 847 848 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td); 849 tid = td->td_tid; 850 thread_free_batched(td); 851 tid_free(tid); 852 thread_count_dec(); 853 } 854 855 void 856 thread_cow_get_proc(struct thread *newtd, struct proc *p) 857 { 858 859 PROC_LOCK_ASSERT(p, MA_OWNED); 860 newtd->td_realucred = crcowget(p->p_ucred); 861 newtd->td_ucred = newtd->td_realucred; 862 newtd->td_limit = lim_hold(p->p_limit); 863 newtd->td_cowgen = p->p_cowgen; 864 } 865 866 void 867 thread_cow_get(struct thread *newtd, struct thread *td) 868 { 869 870 MPASS(td->td_realucred == td->td_ucred); 871 newtd->td_realucred = crcowget(td->td_realucred); 872 newtd->td_ucred = newtd->td_realucred; 873 newtd->td_limit = lim_hold(td->td_limit); 874 newtd->td_cowgen = td->td_cowgen; 875 } 876 877 void 878 thread_cow_free(struct thread *td) 879 { 880 881 if (td->td_realucred != NULL) 882 crcowfree(td); 883 if (td->td_limit != NULL) 884 lim_free(td->td_limit); 885 } 886 887 void 888 thread_cow_update(struct thread *td) 889 { 890 struct proc *p; 891 struct ucred *oldcred; 892 struct plimit *oldlimit; 893 894 p = td->td_proc; 895 PROC_LOCK(p); 896 oldcred = crcowsync(); 897 oldlimit = lim_cowsync(); 898 td->td_cowgen = p->p_cowgen; 899 PROC_UNLOCK(p); 900 if (oldcred != NULL) 901 crfree(oldcred); 902 if (oldlimit != NULL) 903 lim_free(oldlimit); 904 } 905 906 void 907 thread_cow_synced(struct thread *td) 908 { 909 struct proc *p; 910 911 p = td->td_proc; 912 PROC_LOCK_ASSERT(p, MA_OWNED); 913 MPASS(td->td_cowgen != p->p_cowgen); 914 MPASS(td->td_ucred == p->p_ucred); 915 MPASS(td->td_limit == p->p_limit); 916 td->td_cowgen = p->p_cowgen; 917 } 918 919 /* 920 * Discard the current thread and exit from its context. 921 * Always called with scheduler locked. 922 * 923 * Because we can't free a thread while we're operating under its context, 924 * push the current thread into our CPU's deadthread holder. This means 925 * we needn't worry about someone else grabbing our context before we 926 * do a cpu_throw(). 927 */ 928 void 929 thread_exit(void) 930 { 931 uint64_t runtime, new_switchtime; 932 struct thread *td; 933 struct thread *td2; 934 struct proc *p; 935 int wakeup_swapper; 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 wakeup_swapper = thread_unsuspend_one( 982 p->p_singlethread, p, false); 983 if (wakeup_swapper) 984 kick_proc0(); 985 } 986 } 987 988 PCPU_SET(deadthread, td); 989 } else { 990 /* 991 * The last thread is exiting.. but not through exit() 992 */ 993 panic ("thread_exit: Last thread exiting on its own"); 994 } 995 } 996 #ifdef HWPMC_HOOKS 997 /* 998 * If this thread is part of a process that is being tracked by hwpmc(4), 999 * inform the module of the thread's impending exit. 1000 */ 1001 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) { 1002 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 1003 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL); 1004 } else if (PMC_SYSTEM_SAMPLING_ACTIVE()) 1005 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL); 1006 #endif 1007 PROC_UNLOCK(p); 1008 PROC_STATLOCK(p); 1009 thread_lock(td); 1010 PROC_SUNLOCK(p); 1011 1012 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 1013 new_switchtime = cpu_ticks(); 1014 runtime = new_switchtime - PCPU_GET(switchtime); 1015 td->td_runtime += runtime; 1016 td->td_incruntime += runtime; 1017 PCPU_SET(switchtime, new_switchtime); 1018 PCPU_SET(switchticks, ticks); 1019 VM_CNT_INC(v_swtch); 1020 1021 /* Save our resource usage in our process. */ 1022 td->td_ru.ru_nvcsw++; 1023 ruxagg_locked(p, td); 1024 rucollect(&p->p_ru, &td->td_ru); 1025 PROC_STATUNLOCK(p); 1026 1027 TD_SET_STATE(td, TDS_INACTIVE); 1028 #ifdef WITNESS 1029 witness_thread_exit(td); 1030 #endif 1031 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 1032 sched_throw(td); 1033 panic("I'm a teapot!"); 1034 /* NOTREACHED */ 1035 } 1036 1037 /* 1038 * Do any thread specific cleanups that may be needed in wait() 1039 * called with Giant, proc and schedlock not held. 1040 */ 1041 void 1042 thread_wait(struct proc *p) 1043 { 1044 struct thread *td; 1045 1046 mtx_assert(&Giant, MA_NOTOWNED); 1047 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 1048 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 1049 td = FIRST_THREAD_IN_PROC(p); 1050 /* Lock the last thread so we spin until it exits cpu_throw(). */ 1051 thread_lock(td); 1052 thread_unlock(td); 1053 lock_profile_thread_exit(td); 1054 cpuset_rel(td->td_cpuset); 1055 td->td_cpuset = NULL; 1056 cpu_thread_clean(td); 1057 thread_cow_free(td); 1058 callout_drain(&td->td_slpcallout); 1059 thread_reap(); /* check for zombie threads etc. */ 1060 } 1061 1062 /* 1063 * Link a thread to a process. 1064 * set up anything that needs to be initialized for it to 1065 * be used by the process. 1066 */ 1067 void 1068 thread_link(struct thread *td, struct proc *p) 1069 { 1070 1071 /* 1072 * XXX This can't be enabled because it's called for proc0 before 1073 * its lock has been created. 1074 * PROC_LOCK_ASSERT(p, MA_OWNED); 1075 */ 1076 TD_SET_STATE(td, TDS_INACTIVE); 1077 td->td_proc = p; 1078 td->td_flags = TDF_INMEM; 1079 1080 LIST_INIT(&td->td_contested); 1081 LIST_INIT(&td->td_lprof[0]); 1082 LIST_INIT(&td->td_lprof[1]); 1083 #ifdef EPOCH_TRACE 1084 SLIST_INIT(&td->td_epochs); 1085 #endif 1086 sigqueue_init(&td->td_sigqueue, p); 1087 callout_init(&td->td_slpcallout, 1); 1088 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 1089 p->p_numthreads++; 1090 } 1091 1092 /* 1093 * Called from: 1094 * thread_exit() 1095 */ 1096 void 1097 thread_unlink(struct thread *td) 1098 { 1099 struct proc *p = td->td_proc; 1100 1101 PROC_LOCK_ASSERT(p, MA_OWNED); 1102 #ifdef EPOCH_TRACE 1103 MPASS(SLIST_EMPTY(&td->td_epochs)); 1104 #endif 1105 1106 TAILQ_REMOVE(&p->p_threads, td, td_plist); 1107 p->p_numthreads--; 1108 /* could clear a few other things here */ 1109 /* Must NOT clear links to proc! */ 1110 } 1111 1112 static int 1113 calc_remaining(struct proc *p, int mode) 1114 { 1115 int remaining; 1116 1117 PROC_LOCK_ASSERT(p, MA_OWNED); 1118 PROC_SLOCK_ASSERT(p, MA_OWNED); 1119 if (mode == SINGLE_EXIT) 1120 remaining = p->p_numthreads; 1121 else if (mode == SINGLE_BOUNDARY) 1122 remaining = p->p_numthreads - p->p_boundary_count; 1123 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 1124 remaining = p->p_numthreads - p->p_suspcount; 1125 else 1126 panic("calc_remaining: wrong mode %d", mode); 1127 return (remaining); 1128 } 1129 1130 static int 1131 remain_for_mode(int mode) 1132 { 1133 1134 return (mode == SINGLE_ALLPROC ? 0 : 1); 1135 } 1136 1137 static int 1138 weed_inhib(int mode, struct thread *td2, struct proc *p) 1139 { 1140 int wakeup_swapper; 1141 1142 PROC_LOCK_ASSERT(p, MA_OWNED); 1143 PROC_SLOCK_ASSERT(p, MA_OWNED); 1144 THREAD_LOCK_ASSERT(td2, MA_OWNED); 1145 1146 wakeup_swapper = 0; 1147 1148 /* 1149 * Since the thread lock is dropped by the scheduler we have 1150 * to retry to check for races. 1151 */ 1152 restart: 1153 switch (mode) { 1154 case SINGLE_EXIT: 1155 if (TD_IS_SUSPENDED(td2)) { 1156 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 1157 thread_lock(td2); 1158 goto restart; 1159 } 1160 if (TD_CAN_ABORT(td2)) { 1161 wakeup_swapper |= sleepq_abort(td2, EINTR); 1162 return (wakeup_swapper); 1163 } 1164 break; 1165 case SINGLE_BOUNDARY: 1166 case SINGLE_NO_EXIT: 1167 if (TD_IS_SUSPENDED(td2) && 1168 (td2->td_flags & TDF_BOUNDARY) == 0) { 1169 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 1170 thread_lock(td2); 1171 goto restart; 1172 } 1173 if (TD_CAN_ABORT(td2)) { 1174 wakeup_swapper |= sleepq_abort(td2, ERESTART); 1175 return (wakeup_swapper); 1176 } 1177 break; 1178 case SINGLE_ALLPROC: 1179 /* 1180 * ALLPROC suspend tries to avoid spurious EINTR for 1181 * threads sleeping interruptable, by suspending the 1182 * thread directly, similarly to sig_suspend_threads(). 1183 * Since such sleep is not neccessary performed at the user 1184 * boundary, TDF_ALLPROCSUSP is used to avoid immediate 1185 * un-suspend. 1186 */ 1187 if (TD_IS_SUSPENDED(td2) && 1188 (td2->td_flags & TDF_ALLPROCSUSP) == 0) { 1189 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 1190 thread_lock(td2); 1191 goto restart; 1192 } 1193 if (TD_CAN_ABORT(td2)) { 1194 td2->td_flags |= TDF_ALLPROCSUSP; 1195 wakeup_swapper |= sleepq_abort(td2, ERESTART); 1196 return (wakeup_swapper); 1197 } 1198 break; 1199 default: 1200 break; 1201 } 1202 thread_unlock(td2); 1203 return (wakeup_swapper); 1204 } 1205 1206 /* 1207 * Enforce single-threading. 1208 * 1209 * Returns 1 if the caller must abort (another thread is waiting to 1210 * exit the process or similar). Process is locked! 1211 * Returns 0 when you are successfully the only thread running. 1212 * A process has successfully single threaded in the suspend mode when 1213 * There are no threads in user mode. Threads in the kernel must be 1214 * allowed to continue until they get to the user boundary. They may even 1215 * copy out their return values and data before suspending. They may however be 1216 * accelerated in reaching the user boundary as we will wake up 1217 * any sleeping threads that are interruptable. (PCATCH). 1218 */ 1219 int 1220 thread_single(struct proc *p, int mode) 1221 { 1222 struct thread *td; 1223 struct thread *td2; 1224 int remaining, wakeup_swapper; 1225 1226 td = curthread; 1227 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1228 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1229 ("invalid mode %d", mode)); 1230 /* 1231 * If allowing non-ALLPROC singlethreading for non-curproc 1232 * callers, calc_remaining() and remain_for_mode() should be 1233 * adjusted to also account for td->td_proc != p. For now 1234 * this is not implemented because it is not used. 1235 */ 1236 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 1237 (mode != SINGLE_ALLPROC && td->td_proc == p), 1238 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 1239 mtx_assert(&Giant, MA_NOTOWNED); 1240 PROC_LOCK_ASSERT(p, MA_OWNED); 1241 1242 /* 1243 * Is someone already single threading? 1244 * Or may be singlethreading is not needed at all. 1245 */ 1246 if (mode == SINGLE_ALLPROC) { 1247 while ((p->p_flag & P_STOPPED_SINGLE) != 0) { 1248 if ((p->p_flag2 & P2_WEXIT) != 0) 1249 return (1); 1250 msleep(&p->p_flag, &p->p_mtx, PCATCH, "thrsgl", 0); 1251 } 1252 } else if ((p->p_flag & P_HADTHREADS) == 0) 1253 return (0); 1254 if (p->p_singlethread != NULL && p->p_singlethread != td) 1255 return (1); 1256 1257 if (mode == SINGLE_EXIT) { 1258 p->p_flag |= P_SINGLE_EXIT; 1259 p->p_flag &= ~P_SINGLE_BOUNDARY; 1260 } else { 1261 p->p_flag &= ~P_SINGLE_EXIT; 1262 if (mode == SINGLE_BOUNDARY) 1263 p->p_flag |= P_SINGLE_BOUNDARY; 1264 else 1265 p->p_flag &= ~P_SINGLE_BOUNDARY; 1266 } 1267 if (mode == SINGLE_ALLPROC) 1268 p->p_flag |= P_TOTAL_STOP; 1269 p->p_flag |= P_STOPPED_SINGLE; 1270 PROC_SLOCK(p); 1271 p->p_singlethread = td; 1272 remaining = calc_remaining(p, mode); 1273 while (remaining != remain_for_mode(mode)) { 1274 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 1275 goto stopme; 1276 wakeup_swapper = 0; 1277 FOREACH_THREAD_IN_PROC(p, td2) { 1278 if (td2 == td) 1279 continue; 1280 thread_lock(td2); 1281 ast_sched_locked(td2, TDA_SUSPEND); 1282 if (TD_IS_INHIBITED(td2)) { 1283 wakeup_swapper |= weed_inhib(mode, td2, p); 1284 #ifdef SMP 1285 } else if (TD_IS_RUNNING(td2)) { 1286 forward_signal(td2); 1287 thread_unlock(td2); 1288 #endif 1289 } else 1290 thread_unlock(td2); 1291 } 1292 if (wakeup_swapper) 1293 kick_proc0(); 1294 remaining = calc_remaining(p, mode); 1295 1296 /* 1297 * Maybe we suspended some threads.. was it enough? 1298 */ 1299 if (remaining == remain_for_mode(mode)) 1300 break; 1301 1302 stopme: 1303 /* 1304 * Wake us up when everyone else has suspended. 1305 * In the mean time we suspend as well. 1306 */ 1307 thread_suspend_switch(td, p); 1308 remaining = calc_remaining(p, mode); 1309 } 1310 if (mode == SINGLE_EXIT) { 1311 /* 1312 * Convert the process to an unthreaded process. The 1313 * SINGLE_EXIT is called by exit1() or execve(), in 1314 * both cases other threads must be retired. 1315 */ 1316 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 1317 p->p_singlethread = NULL; 1318 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 1319 1320 /* 1321 * Wait for any remaining threads to exit cpu_throw(). 1322 */ 1323 while (p->p_exitthreads != 0) { 1324 PROC_SUNLOCK(p); 1325 PROC_UNLOCK(p); 1326 sched_relinquish(td); 1327 PROC_LOCK(p); 1328 PROC_SLOCK(p); 1329 } 1330 } else if (mode == SINGLE_BOUNDARY) { 1331 /* 1332 * Wait until all suspended threads are removed from 1333 * the processors. The thread_suspend_check() 1334 * increments p_boundary_count while it is still 1335 * running, which makes it possible for the execve() 1336 * to destroy vmspace while our other threads are 1337 * still using the address space. 1338 * 1339 * We lock the thread, which is only allowed to 1340 * succeed after context switch code finished using 1341 * the address space. 1342 */ 1343 FOREACH_THREAD_IN_PROC(p, td2) { 1344 if (td2 == td) 1345 continue; 1346 thread_lock(td2); 1347 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 1348 ("td %p not on boundary", td2)); 1349 KASSERT(TD_IS_SUSPENDED(td2), 1350 ("td %p is not suspended", td2)); 1351 thread_unlock(td2); 1352 } 1353 } 1354 PROC_SUNLOCK(p); 1355 return (0); 1356 } 1357 1358 bool 1359 thread_suspend_check_needed(void) 1360 { 1361 struct proc *p; 1362 struct thread *td; 1363 1364 td = curthread; 1365 p = td->td_proc; 1366 PROC_LOCK_ASSERT(p, MA_OWNED); 1367 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 1368 (td->td_dbgflags & TDB_SUSPEND) != 0)); 1369 } 1370 1371 /* 1372 * Called in from locations that can safely check to see 1373 * whether we have to suspend or at least throttle for a 1374 * single-thread event (e.g. fork). 1375 * 1376 * Such locations include userret(). 1377 * If the "return_instead" argument is non zero, the thread must be able to 1378 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 1379 * 1380 * The 'return_instead' argument tells the function if it may do a 1381 * thread_exit() or suspend, or whether the caller must abort and back 1382 * out instead. 1383 * 1384 * If the thread that set the single_threading request has set the 1385 * P_SINGLE_EXIT bit in the process flags then this call will never return 1386 * if 'return_instead' is false, but will exit. 1387 * 1388 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 1389 *---------------+--------------------+--------------------- 1390 * 0 | returns 0 | returns 0 or 1 1391 * | when ST ends | immediately 1392 *---------------+--------------------+--------------------- 1393 * 1 | thread exits | returns 1 1394 * | | immediately 1395 * 0 = thread_exit() or suspension ok, 1396 * other = return error instead of stopping the thread. 1397 * 1398 * While a full suspension is under effect, even a single threading 1399 * thread would be suspended if it made this call (but it shouldn't). 1400 * This call should only be made from places where 1401 * thread_exit() would be safe as that may be the outcome unless 1402 * return_instead is set. 1403 */ 1404 int 1405 thread_suspend_check(int return_instead) 1406 { 1407 struct thread *td; 1408 struct proc *p; 1409 int wakeup_swapper; 1410 1411 td = curthread; 1412 p = td->td_proc; 1413 mtx_assert(&Giant, MA_NOTOWNED); 1414 PROC_LOCK_ASSERT(p, MA_OWNED); 1415 while (thread_suspend_check_needed()) { 1416 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1417 KASSERT(p->p_singlethread != NULL, 1418 ("singlethread not set")); 1419 /* 1420 * The only suspension in action is a 1421 * single-threading. Single threader need not stop. 1422 * It is safe to access p->p_singlethread unlocked 1423 * because it can only be set to our address by us. 1424 */ 1425 if (p->p_singlethread == td) 1426 return (0); /* Exempt from stopping. */ 1427 } 1428 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 1429 return (EINTR); 1430 1431 /* Should we goto user boundary if we didn't come from there? */ 1432 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1433 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 1434 return (ERESTART); 1435 1436 /* 1437 * Ignore suspend requests if they are deferred. 1438 */ 1439 if ((td->td_flags & TDF_SBDRY) != 0) { 1440 KASSERT(return_instead, 1441 ("TDF_SBDRY set for unsafe thread_suspend_check")); 1442 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 1443 (TDF_SEINTR | TDF_SERESTART), 1444 ("both TDF_SEINTR and TDF_SERESTART")); 1445 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 1446 } 1447 1448 /* 1449 * If the process is waiting for us to exit, 1450 * this thread should just suicide. 1451 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 1452 */ 1453 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 1454 PROC_UNLOCK(p); 1455 1456 /* 1457 * Allow Linux emulation layer to do some work 1458 * before thread suicide. 1459 */ 1460 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 1461 (p->p_sysent->sv_thread_detach)(td); 1462 umtx_thread_exit(td); 1463 kern_thr_exit(td); 1464 panic("stopped thread did not exit"); 1465 } 1466 1467 PROC_SLOCK(p); 1468 thread_stopped(p); 1469 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1470 if (p->p_numthreads == p->p_suspcount + 1) { 1471 thread_lock(p->p_singlethread); 1472 wakeup_swapper = thread_unsuspend_one( 1473 p->p_singlethread, p, false); 1474 if (wakeup_swapper) 1475 kick_proc0(); 1476 } 1477 } 1478 PROC_UNLOCK(p); 1479 thread_lock(td); 1480 /* 1481 * When a thread suspends, it just 1482 * gets taken off all queues. 1483 */ 1484 thread_suspend_one(td); 1485 if (return_instead == 0) { 1486 p->p_boundary_count++; 1487 td->td_flags |= TDF_BOUNDARY; 1488 } 1489 PROC_SUNLOCK(p); 1490 mi_switch(SW_INVOL | SWT_SUSPEND); 1491 PROC_LOCK(p); 1492 } 1493 return (0); 1494 } 1495 1496 /* 1497 * Check for possible stops and suspensions while executing a 1498 * casueword or similar transiently failing operation. 1499 * 1500 * The sleep argument controls whether the function can handle a stop 1501 * request itself or it should return ERESTART and the request is 1502 * proceed at the kernel/user boundary in ast. 1503 * 1504 * Typically, when retrying due to casueword(9) failure (rv == 1), we 1505 * should handle the stop requests there, with exception of cases when 1506 * the thread owns a kernel resource, for instance busied the umtx 1507 * key, or when functions return immediately if thread_check_susp() 1508 * returned non-zero. On the other hand, retrying the whole lock 1509 * operation, we better not stop there but delegate the handling to 1510 * ast. 1511 * 1512 * If the request is for thread termination P_SINGLE_EXIT, we cannot 1513 * handle it at all, and simply return EINTR. 1514 */ 1515 int 1516 thread_check_susp(struct thread *td, bool sleep) 1517 { 1518 struct proc *p; 1519 int error; 1520 1521 /* 1522 * The check for TDA_SUSPEND is racy, but it is enough to 1523 * eventually break the lockstep loop. 1524 */ 1525 if (!td_ast_pending(td, TDA_SUSPEND)) 1526 return (0); 1527 error = 0; 1528 p = td->td_proc; 1529 PROC_LOCK(p); 1530 if (p->p_flag & P_SINGLE_EXIT) 1531 error = EINTR; 1532 else if (P_SHOULDSTOP(p) || 1533 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) 1534 error = sleep ? thread_suspend_check(0) : ERESTART; 1535 PROC_UNLOCK(p); 1536 return (error); 1537 } 1538 1539 void 1540 thread_suspend_switch(struct thread *td, struct proc *p) 1541 { 1542 1543 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1544 PROC_LOCK_ASSERT(p, MA_OWNED); 1545 PROC_SLOCK_ASSERT(p, MA_OWNED); 1546 /* 1547 * We implement thread_suspend_one in stages here to avoid 1548 * dropping the proc lock while the thread lock is owned. 1549 */ 1550 if (p == td->td_proc) { 1551 thread_stopped(p); 1552 p->p_suspcount++; 1553 } 1554 PROC_UNLOCK(p); 1555 thread_lock(td); 1556 ast_unsched_locked(td, TDA_SUSPEND); 1557 TD_SET_SUSPENDED(td); 1558 sched_sleep(td, 0); 1559 PROC_SUNLOCK(p); 1560 DROP_GIANT(); 1561 mi_switch(SW_VOL | SWT_SUSPEND); 1562 PICKUP_GIANT(); 1563 PROC_LOCK(p); 1564 PROC_SLOCK(p); 1565 } 1566 1567 void 1568 thread_suspend_one(struct thread *td) 1569 { 1570 struct proc *p; 1571 1572 p = td->td_proc; 1573 PROC_SLOCK_ASSERT(p, MA_OWNED); 1574 THREAD_LOCK_ASSERT(td, MA_OWNED); 1575 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1576 p->p_suspcount++; 1577 ast_unsched_locked(td, TDA_SUSPEND); 1578 TD_SET_SUSPENDED(td); 1579 sched_sleep(td, 0); 1580 } 1581 1582 static int 1583 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1584 { 1585 1586 THREAD_LOCK_ASSERT(td, MA_OWNED); 1587 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1588 TD_CLR_SUSPENDED(td); 1589 td->td_flags &= ~TDF_ALLPROCSUSP; 1590 if (td->td_proc == p) { 1591 PROC_SLOCK_ASSERT(p, MA_OWNED); 1592 p->p_suspcount--; 1593 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1594 td->td_flags &= ~TDF_BOUNDARY; 1595 p->p_boundary_count--; 1596 } 1597 } 1598 return (setrunnable(td, 0)); 1599 } 1600 1601 void 1602 thread_run_flash(struct thread *td) 1603 { 1604 struct proc *p; 1605 1606 p = td->td_proc; 1607 PROC_LOCK_ASSERT(p, MA_OWNED); 1608 1609 if (TD_ON_SLEEPQ(td)) 1610 sleepq_remove_nested(td); 1611 else 1612 thread_lock(td); 1613 1614 THREAD_LOCK_ASSERT(td, MA_OWNED); 1615 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1616 1617 TD_CLR_SUSPENDED(td); 1618 PROC_SLOCK(p); 1619 MPASS(p->p_suspcount > 0); 1620 p->p_suspcount--; 1621 PROC_SUNLOCK(p); 1622 if (setrunnable(td, 0)) 1623 kick_proc0(); 1624 } 1625 1626 /* 1627 * Allow all threads blocked by single threading to continue running. 1628 */ 1629 void 1630 thread_unsuspend(struct proc *p) 1631 { 1632 struct thread *td; 1633 int wakeup_swapper; 1634 1635 PROC_LOCK_ASSERT(p, MA_OWNED); 1636 PROC_SLOCK_ASSERT(p, MA_OWNED); 1637 wakeup_swapper = 0; 1638 if (!P_SHOULDSTOP(p)) { 1639 FOREACH_THREAD_IN_PROC(p, td) { 1640 thread_lock(td); 1641 if (TD_IS_SUSPENDED(td)) 1642 wakeup_swapper |= thread_unsuspend_one(td, p, 1643 true); 1644 else 1645 thread_unlock(td); 1646 } 1647 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1648 p->p_numthreads == p->p_suspcount) { 1649 /* 1650 * Stopping everything also did the job for the single 1651 * threading request. Now we've downgraded to single-threaded, 1652 * let it continue. 1653 */ 1654 if (p->p_singlethread->td_proc == p) { 1655 thread_lock(p->p_singlethread); 1656 wakeup_swapper = thread_unsuspend_one( 1657 p->p_singlethread, p, false); 1658 } 1659 } 1660 if (wakeup_swapper) 1661 kick_proc0(); 1662 } 1663 1664 /* 1665 * End the single threading mode.. 1666 */ 1667 void 1668 thread_single_end(struct proc *p, int mode) 1669 { 1670 struct thread *td; 1671 int wakeup_swapper; 1672 1673 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1674 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1675 ("invalid mode %d", mode)); 1676 PROC_LOCK_ASSERT(p, MA_OWNED); 1677 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1678 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1679 ("mode %d does not match P_TOTAL_STOP", mode)); 1680 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1681 ("thread_single_end from other thread %p %p", 1682 curthread, p->p_singlethread)); 1683 KASSERT(mode != SINGLE_BOUNDARY || 1684 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1685 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1686 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1687 P_TOTAL_STOP); 1688 PROC_SLOCK(p); 1689 p->p_singlethread = NULL; 1690 wakeup_swapper = 0; 1691 /* 1692 * If there are other threads they may now run, 1693 * unless of course there is a blanket 'stop order' 1694 * on the process. The single threader must be allowed 1695 * to continue however as this is a bad place to stop. 1696 */ 1697 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1698 FOREACH_THREAD_IN_PROC(p, td) { 1699 thread_lock(td); 1700 if (TD_IS_SUSPENDED(td)) { 1701 wakeup_swapper |= thread_unsuspend_one(td, p, 1702 true); 1703 } else 1704 thread_unlock(td); 1705 } 1706 } 1707 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1708 ("inconsistent boundary count %d", p->p_boundary_count)); 1709 PROC_SUNLOCK(p); 1710 if (wakeup_swapper) 1711 kick_proc0(); 1712 wakeup(&p->p_flag); 1713 } 1714 1715 /* 1716 * Locate a thread by number and return with proc lock held. 1717 * 1718 * thread exit establishes proc -> tidhash lock ordering, but lookup 1719 * takes tidhash first and needs to return locked proc. 1720 * 1721 * The problem is worked around by relying on type-safety of both 1722 * structures and doing the work in 2 steps: 1723 * - tidhash-locked lookup which saves both thread and proc pointers 1724 * - proc-locked verification that the found thread still matches 1725 */ 1726 static bool 1727 tdfind_hash(lwpid_t tid, pid_t pid, struct proc **pp, struct thread **tdp) 1728 { 1729 #define RUN_THRESH 16 1730 struct proc *p; 1731 struct thread *td; 1732 int run; 1733 bool locked; 1734 1735 run = 0; 1736 rw_rlock(TIDHASHLOCK(tid)); 1737 locked = true; 1738 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1739 if (td->td_tid != tid) { 1740 run++; 1741 continue; 1742 } 1743 p = td->td_proc; 1744 if (pid != -1 && p->p_pid != pid) { 1745 td = NULL; 1746 break; 1747 } 1748 if (run > RUN_THRESH) { 1749 if (rw_try_upgrade(TIDHASHLOCK(tid))) { 1750 LIST_REMOVE(td, td_hash); 1751 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1752 td, td_hash); 1753 rw_wunlock(TIDHASHLOCK(tid)); 1754 locked = false; 1755 break; 1756 } 1757 } 1758 break; 1759 } 1760 if (locked) 1761 rw_runlock(TIDHASHLOCK(tid)); 1762 if (td == NULL) 1763 return (false); 1764 *pp = p; 1765 *tdp = td; 1766 return (true); 1767 } 1768 1769 struct thread * 1770 tdfind(lwpid_t tid, pid_t pid) 1771 { 1772 struct proc *p; 1773 struct thread *td; 1774 1775 td = curthread; 1776 if (td->td_tid == tid) { 1777 if (pid != -1 && td->td_proc->p_pid != pid) 1778 return (NULL); 1779 PROC_LOCK(td->td_proc); 1780 return (td); 1781 } 1782 1783 for (;;) { 1784 if (!tdfind_hash(tid, pid, &p, &td)) 1785 return (NULL); 1786 PROC_LOCK(p); 1787 if (td->td_tid != tid) { 1788 PROC_UNLOCK(p); 1789 continue; 1790 } 1791 if (td->td_proc != p) { 1792 PROC_UNLOCK(p); 1793 continue; 1794 } 1795 if (p->p_state == PRS_NEW) { 1796 PROC_UNLOCK(p); 1797 return (NULL); 1798 } 1799 return (td); 1800 } 1801 } 1802 1803 void 1804 tidhash_add(struct thread *td) 1805 { 1806 rw_wlock(TIDHASHLOCK(td->td_tid)); 1807 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1808 rw_wunlock(TIDHASHLOCK(td->td_tid)); 1809 } 1810 1811 void 1812 tidhash_remove(struct thread *td) 1813 { 1814 1815 rw_wlock(TIDHASHLOCK(td->td_tid)); 1816 LIST_REMOVE(td, td_hash); 1817 rw_wunlock(TIDHASHLOCK(td->td_tid)); 1818 } 1819