1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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 __FBSDID("$FreeBSD$"); 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/kernel.h> 40 #include <sys/lock.h> 41 #include <sys/msan.h> 42 #include <sys/mutex.h> 43 #include <sys/proc.h> 44 #include <sys/bitstring.h> 45 #include <sys/epoch.h> 46 #include <sys/rangelock.h> 47 #include <sys/resourcevar.h> 48 #include <sys/sdt.h> 49 #include <sys/smp.h> 50 #include <sys/sched.h> 51 #include <sys/sleepqueue.h> 52 #include <sys/selinfo.h> 53 #include <sys/syscallsubr.h> 54 #include <sys/dtrace_bsd.h> 55 #include <sys/sysent.h> 56 #include <sys/turnstile.h> 57 #include <sys/taskqueue.h> 58 #include <sys/ktr.h> 59 #include <sys/rwlock.h> 60 #include <sys/umtxvar.h> 61 #include <sys/vmmeter.h> 62 #include <sys/cpuset.h> 63 #ifdef HWPMC_HOOKS 64 #include <sys/pmckern.h> 65 #endif 66 #include <sys/priv.h> 67 68 #include <security/audit/audit.h> 69 70 #include <vm/pmap.h> 71 #include <vm/vm.h> 72 #include <vm/vm_extern.h> 73 #include <vm/uma.h> 74 #include <vm/vm_phys.h> 75 #include <sys/eventhandler.h> 76 77 /* 78 * Asserts below verify the stability of struct thread and struct proc 79 * layout, as exposed by KBI to modules. On head, the KBI is allowed 80 * to drift, change to the structures must be accompanied by the 81 * assert update. 82 * 83 * On the stable branches after KBI freeze, conditions must not be 84 * violated. Typically new fields are moved to the end of the 85 * structures. 86 */ 87 #ifdef __amd64__ 88 _Static_assert(offsetof(struct thread, td_flags) == 0x108, 89 "struct thread KBI td_flags"); 90 _Static_assert(offsetof(struct thread, td_pflags) == 0x110, 91 "struct thread KBI td_pflags"); 92 _Static_assert(offsetof(struct thread, td_frame) == 0x4a8, 93 "struct thread KBI td_frame"); 94 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6b0, 95 "struct thread KBI td_emuldata"); 96 _Static_assert(offsetof(struct proc, p_flag) == 0xb8, 97 "struct proc KBI p_flag"); 98 _Static_assert(offsetof(struct proc, p_pid) == 0xc4, 99 "struct proc KBI p_pid"); 100 _Static_assert(offsetof(struct proc, p_filemon) == 0x3c8, 101 "struct proc KBI p_filemon"); 102 _Static_assert(offsetof(struct proc, p_comm) == 0x3e0, 103 "struct proc KBI p_comm"); 104 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4c8, 105 "struct proc KBI p_emuldata"); 106 #endif 107 #ifdef __i386__ 108 _Static_assert(offsetof(struct thread, td_flags) == 0x9c, 109 "struct thread KBI td_flags"); 110 _Static_assert(offsetof(struct thread, td_pflags) == 0xa4, 111 "struct thread KBI td_pflags"); 112 _Static_assert(offsetof(struct thread, td_frame) == 0x308, 113 "struct thread KBI td_frame"); 114 _Static_assert(offsetof(struct thread, td_emuldata) == 0x34c, 115 "struct thread KBI td_emuldata"); 116 _Static_assert(offsetof(struct proc, p_flag) == 0x6c, 117 "struct proc KBI p_flag"); 118 _Static_assert(offsetof(struct proc, p_pid) == 0x78, 119 "struct proc KBI p_pid"); 120 _Static_assert(offsetof(struct proc, p_filemon) == 0x270, 121 "struct proc KBI p_filemon"); 122 _Static_assert(offsetof(struct proc, p_comm) == 0x284, 123 "struct proc KBI p_comm"); 124 _Static_assert(offsetof(struct proc, p_emuldata) == 0x310, 125 "struct proc KBI p_emuldata"); 126 #endif 127 128 SDT_PROVIDER_DECLARE(proc); 129 SDT_PROBE_DEFINE(proc, , , lwp__exit); 130 131 /* 132 * thread related storage. 133 */ 134 static uma_zone_t thread_zone; 135 136 struct thread_domain_data { 137 struct thread *tdd_zombies; 138 int tdd_reapticks; 139 } __aligned(CACHE_LINE_SIZE); 140 141 static struct thread_domain_data thread_domain_data[MAXMEMDOM]; 142 143 static struct task thread_reap_task; 144 static struct callout thread_reap_callout; 145 146 static void thread_zombie(struct thread *); 147 static void thread_reap(void); 148 static void thread_reap_all(void); 149 static void thread_reap_task_cb(void *, int); 150 static void thread_reap_callout_cb(void *); 151 static int thread_unsuspend_one(struct thread *td, struct proc *p, 152 bool boundary); 153 static void thread_free_batched(struct thread *td); 154 155 static __exclusive_cache_line struct mtx tid_lock; 156 static bitstr_t *tid_bitmap; 157 158 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 159 160 static int maxthread; 161 SYSCTL_INT(_kern, OID_AUTO, maxthread, CTLFLAG_RDTUN, 162 &maxthread, 0, "Maximum number of threads"); 163 164 static __exclusive_cache_line int nthreads; 165 166 static LIST_HEAD(tidhashhead, thread) *tidhashtbl; 167 static u_long tidhash; 168 static u_long tidhashlock; 169 static struct rwlock *tidhashtbl_lock; 170 #define TIDHASH(tid) (&tidhashtbl[(tid) & tidhash]) 171 #define TIDHASHLOCK(tid) (&tidhashtbl_lock[(tid) & tidhashlock]) 172 173 EVENTHANDLER_LIST_DEFINE(thread_ctor); 174 EVENTHANDLER_LIST_DEFINE(thread_dtor); 175 EVENTHANDLER_LIST_DEFINE(thread_init); 176 EVENTHANDLER_LIST_DEFINE(thread_fini); 177 178 static bool 179 thread_count_inc_try(void) 180 { 181 int nthreads_new; 182 183 nthreads_new = atomic_fetchadd_int(&nthreads, 1) + 1; 184 if (nthreads_new >= maxthread - 100) { 185 if (priv_check_cred(curthread->td_ucred, PRIV_MAXPROC) != 0 || 186 nthreads_new >= maxthread) { 187 atomic_subtract_int(&nthreads, 1); 188 return (false); 189 } 190 } 191 return (true); 192 } 193 194 static bool 195 thread_count_inc(void) 196 { 197 static struct timeval lastfail; 198 static int curfail; 199 200 thread_reap(); 201 if (thread_count_inc_try()) { 202 return (true); 203 } 204 205 thread_reap_all(); 206 if (thread_count_inc_try()) { 207 return (true); 208 } 209 210 if (ppsratecheck(&lastfail, &curfail, 1)) { 211 printf("maxthread limit exceeded by uid %u " 212 "(pid %d); consider increasing kern.maxthread\n", 213 curthread->td_ucred->cr_ruid, curproc->p_pid); 214 } 215 return (false); 216 } 217 218 static void 219 thread_count_sub(int n) 220 { 221 222 atomic_subtract_int(&nthreads, n); 223 } 224 225 static void 226 thread_count_dec(void) 227 { 228 229 thread_count_sub(1); 230 } 231 232 static lwpid_t 233 tid_alloc(void) 234 { 235 static lwpid_t trytid; 236 lwpid_t tid; 237 238 mtx_lock(&tid_lock); 239 /* 240 * It is an invariant that the bitmap is big enough to hold maxthread 241 * IDs. If we got to this point there has to be at least one free. 242 */ 243 if (trytid >= maxthread) 244 trytid = 0; 245 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 246 if (tid == -1) { 247 KASSERT(trytid != 0, ("unexpectedly ran out of IDs")); 248 trytid = 0; 249 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 250 KASSERT(tid != -1, ("unexpectedly ran out of IDs")); 251 } 252 bit_set(tid_bitmap, tid); 253 trytid = tid + 1; 254 mtx_unlock(&tid_lock); 255 return (tid + NO_PID); 256 } 257 258 static void 259 tid_free_locked(lwpid_t rtid) 260 { 261 lwpid_t tid; 262 263 mtx_assert(&tid_lock, MA_OWNED); 264 KASSERT(rtid >= NO_PID, 265 ("%s: invalid tid %d\n", __func__, rtid)); 266 tid = rtid - NO_PID; 267 KASSERT(bit_test(tid_bitmap, tid) != 0, 268 ("thread ID %d not allocated\n", rtid)); 269 bit_clear(tid_bitmap, tid); 270 } 271 272 static void 273 tid_free(lwpid_t rtid) 274 { 275 276 mtx_lock(&tid_lock); 277 tid_free_locked(rtid); 278 mtx_unlock(&tid_lock); 279 } 280 281 static void 282 tid_free_batch(lwpid_t *batch, int n) 283 { 284 int i; 285 286 mtx_lock(&tid_lock); 287 for (i = 0; i < n; i++) { 288 tid_free_locked(batch[i]); 289 } 290 mtx_unlock(&tid_lock); 291 } 292 293 /* 294 * Batching for thread reapping. 295 */ 296 struct tidbatch { 297 lwpid_t tab[16]; 298 int n; 299 }; 300 301 static void 302 tidbatch_prep(struct tidbatch *tb) 303 { 304 305 tb->n = 0; 306 } 307 308 static void 309 tidbatch_add(struct tidbatch *tb, struct thread *td) 310 { 311 312 KASSERT(tb->n < nitems(tb->tab), 313 ("%s: count too high %d", __func__, tb->n)); 314 tb->tab[tb->n] = td->td_tid; 315 tb->n++; 316 } 317 318 static void 319 tidbatch_process(struct tidbatch *tb) 320 { 321 322 KASSERT(tb->n <= nitems(tb->tab), 323 ("%s: count too high %d", __func__, tb->n)); 324 if (tb->n == nitems(tb->tab)) { 325 tid_free_batch(tb->tab, tb->n); 326 tb->n = 0; 327 } 328 } 329 330 static void 331 tidbatch_final(struct tidbatch *tb) 332 { 333 334 KASSERT(tb->n <= nitems(tb->tab), 335 ("%s: count too high %d", __func__, tb->n)); 336 if (tb->n != 0) { 337 tid_free_batch(tb->tab, tb->n); 338 } 339 } 340 341 /* 342 * Prepare a thread for use. 343 */ 344 static int 345 thread_ctor(void *mem, int size, void *arg, int flags) 346 { 347 struct thread *td; 348 349 td = (struct thread *)mem; 350 TD_SET_STATE(td, TDS_INACTIVE); 351 td->td_lastcpu = td->td_oncpu = NOCPU; 352 353 /* 354 * Note that td_critnest begins life as 1 because the thread is not 355 * running and is thereby implicitly waiting to be on the receiving 356 * end of a context switch. 357 */ 358 td->td_critnest = 1; 359 td->td_lend_user_pri = PRI_MAX; 360 #ifdef AUDIT 361 audit_thread_alloc(td); 362 #endif 363 #ifdef KDTRACE_HOOKS 364 kdtrace_thread_ctor(td); 365 #endif 366 umtx_thread_alloc(td); 367 MPASS(td->td_sel == NULL); 368 return (0); 369 } 370 371 /* 372 * Reclaim a thread after use. 373 */ 374 static void 375 thread_dtor(void *mem, int size, void *arg) 376 { 377 struct thread *td; 378 379 td = (struct thread *)mem; 380 381 #ifdef INVARIANTS 382 /* Verify that this thread is in a safe state to free. */ 383 switch (TD_GET_STATE(td)) { 384 case TDS_INHIBITED: 385 case TDS_RUNNING: 386 case TDS_CAN_RUN: 387 case TDS_RUNQ: 388 /* 389 * We must never unlink a thread that is in one of 390 * these states, because it is currently active. 391 */ 392 panic("bad state for thread unlinking"); 393 /* NOTREACHED */ 394 case TDS_INACTIVE: 395 break; 396 default: 397 panic("bad thread state"); 398 /* NOTREACHED */ 399 } 400 #endif 401 #ifdef AUDIT 402 audit_thread_free(td); 403 #endif 404 #ifdef KDTRACE_HOOKS 405 kdtrace_thread_dtor(td); 406 #endif 407 /* Free all OSD associated to this thread. */ 408 osd_thread_exit(td); 409 td_softdep_cleanup(td); 410 MPASS(td->td_su == NULL); 411 seltdfini(td); 412 } 413 414 /* 415 * Initialize type-stable parts of a thread (when newly created). 416 */ 417 static int 418 thread_init(void *mem, int size, int flags) 419 { 420 struct thread *td; 421 422 td = (struct thread *)mem; 423 424 td->td_allocdomain = vm_phys_domain(vtophys(td)); 425 td->td_sleepqueue = sleepq_alloc(); 426 td->td_turnstile = turnstile_alloc(); 427 td->td_rlqe = NULL; 428 EVENTHANDLER_DIRECT_INVOKE(thread_init, td); 429 umtx_thread_init(td); 430 td->td_kstack = 0; 431 td->td_sel = NULL; 432 return (0); 433 } 434 435 /* 436 * Tear down type-stable parts of a thread (just before being discarded). 437 */ 438 static void 439 thread_fini(void *mem, int size) 440 { 441 struct thread *td; 442 443 td = (struct thread *)mem; 444 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td); 445 rlqentry_free(td->td_rlqe); 446 turnstile_free(td->td_turnstile); 447 sleepq_free(td->td_sleepqueue); 448 umtx_thread_fini(td); 449 MPASS(td->td_sel == NULL); 450 } 451 452 /* 453 * For a newly created process, 454 * link up all the structures and its initial threads etc. 455 * called from: 456 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 457 * proc_dtor() (should go away) 458 * proc_init() 459 */ 460 void 461 proc_linkup0(struct proc *p, struct thread *td) 462 { 463 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 464 proc_linkup(p, td); 465 } 466 467 void 468 proc_linkup(struct proc *p, struct thread *td) 469 { 470 471 sigqueue_init(&p->p_sigqueue, p); 472 p->p_ksi = ksiginfo_alloc(1); 473 if (p->p_ksi != NULL) { 474 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 475 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 476 } 477 LIST_INIT(&p->p_mqnotifier); 478 p->p_numthreads = 0; 479 thread_link(td, p); 480 } 481 482 extern int max_threads_per_proc; 483 484 /* 485 * Initialize global thread allocation resources. 486 */ 487 void 488 threadinit(void) 489 { 490 u_long i; 491 lwpid_t tid0; 492 uint32_t flags; 493 494 /* 495 * Place an upper limit on threads which can be allocated. 496 * 497 * Note that other factors may make the de facto limit much lower. 498 * 499 * Platform limits are somewhat arbitrary but deemed "more than good 500 * enough" for the foreseable future. 501 */ 502 if (maxthread == 0) { 503 #ifdef _LP64 504 maxthread = MIN(maxproc * max_threads_per_proc, 1000000); 505 #else 506 maxthread = MIN(maxproc * max_threads_per_proc, 100000); 507 #endif 508 } 509 510 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 511 tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK); 512 /* 513 * Handle thread0. 514 */ 515 thread_count_inc(); 516 tid0 = tid_alloc(); 517 if (tid0 != THREAD0_TID) 518 panic("tid0 %d != %d\n", tid0, THREAD0_TID); 519 520 flags = UMA_ZONE_NOFREE; 521 #ifdef __aarch64__ 522 /* 523 * Force thread structures to be allocated from the direct map. 524 * Otherwise, superpage promotions and demotions may temporarily 525 * invalidate thread structure mappings. For most dynamically allocated 526 * structures this is not a problem, but translation faults cannot be 527 * handled without accessing curthread. 528 */ 529 flags |= UMA_ZONE_CONTIG; 530 #endif 531 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 532 thread_ctor, thread_dtor, thread_init, thread_fini, 533 32 - 1, flags); 534 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 535 tidhashlock = (tidhash + 1) / 64; 536 if (tidhashlock > 0) 537 tidhashlock--; 538 tidhashtbl_lock = malloc(sizeof(*tidhashtbl_lock) * (tidhashlock + 1), 539 M_TIDHASH, M_WAITOK | M_ZERO); 540 for (i = 0; i < tidhashlock + 1; i++) 541 rw_init(&tidhashtbl_lock[i], "tidhash"); 542 543 TASK_INIT(&thread_reap_task, 0, thread_reap_task_cb, NULL); 544 callout_init(&thread_reap_callout, 1); 545 callout_reset(&thread_reap_callout, 5 * hz, 546 thread_reap_callout_cb, NULL); 547 } 548 549 /* 550 * Place an unused thread on the zombie list. 551 */ 552 void 553 thread_zombie(struct thread *td) 554 { 555 struct thread_domain_data *tdd; 556 struct thread *ztd; 557 558 tdd = &thread_domain_data[td->td_allocdomain]; 559 ztd = atomic_load_ptr(&tdd->tdd_zombies); 560 for (;;) { 561 td->td_zombie = ztd; 562 if (atomic_fcmpset_rel_ptr((uintptr_t *)&tdd->tdd_zombies, 563 (uintptr_t *)&ztd, (uintptr_t)td)) 564 break; 565 continue; 566 } 567 } 568 569 /* 570 * Release a thread that has exited after cpu_throw(). 571 */ 572 void 573 thread_stash(struct thread *td) 574 { 575 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 576 thread_zombie(td); 577 } 578 579 /* 580 * Reap zombies from passed domain. 581 */ 582 static void 583 thread_reap_domain(struct thread_domain_data *tdd) 584 { 585 struct thread *itd, *ntd; 586 struct tidbatch tidbatch; 587 struct credbatch credbatch; 588 int tdcount; 589 struct plimit *lim; 590 int limcount; 591 592 /* 593 * Reading upfront is pessimal if followed by concurrent atomic_swap, 594 * but most of the time the list is empty. 595 */ 596 if (tdd->tdd_zombies == NULL) 597 return; 598 599 itd = (struct thread *)atomic_swap_ptr((uintptr_t *)&tdd->tdd_zombies, 600 (uintptr_t)NULL); 601 if (itd == NULL) 602 return; 603 604 /* 605 * Multiple CPUs can get here, the race is fine as ticks is only 606 * advisory. 607 */ 608 tdd->tdd_reapticks = ticks; 609 610 tidbatch_prep(&tidbatch); 611 credbatch_prep(&credbatch); 612 tdcount = 0; 613 lim = NULL; 614 limcount = 0; 615 616 while (itd != NULL) { 617 ntd = itd->td_zombie; 618 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, itd); 619 tidbatch_add(&tidbatch, itd); 620 credbatch_add(&credbatch, itd); 621 MPASS(itd->td_limit != NULL); 622 if (lim != itd->td_limit) { 623 if (limcount != 0) { 624 lim_freen(lim, limcount); 625 limcount = 0; 626 } 627 } 628 lim = itd->td_limit; 629 limcount++; 630 thread_free_batched(itd); 631 tidbatch_process(&tidbatch); 632 credbatch_process(&credbatch); 633 tdcount++; 634 if (tdcount == 32) { 635 thread_count_sub(tdcount); 636 tdcount = 0; 637 } 638 itd = ntd; 639 } 640 641 tidbatch_final(&tidbatch); 642 credbatch_final(&credbatch); 643 if (tdcount != 0) { 644 thread_count_sub(tdcount); 645 } 646 MPASS(limcount != 0); 647 lim_freen(lim, limcount); 648 } 649 650 /* 651 * Reap zombies from all domains. 652 */ 653 static void 654 thread_reap_all(void) 655 { 656 struct thread_domain_data *tdd; 657 int i, domain; 658 659 domain = PCPU_GET(domain); 660 for (i = 0; i < vm_ndomains; i++) { 661 tdd = &thread_domain_data[(i + domain) % vm_ndomains]; 662 thread_reap_domain(tdd); 663 } 664 } 665 666 /* 667 * Reap zombies from local domain. 668 */ 669 static void 670 thread_reap(void) 671 { 672 struct thread_domain_data *tdd; 673 int domain; 674 675 domain = PCPU_GET(domain); 676 tdd = &thread_domain_data[domain]; 677 678 thread_reap_domain(tdd); 679 } 680 681 static void 682 thread_reap_task_cb(void *arg __unused, int pending __unused) 683 { 684 685 thread_reap_all(); 686 } 687 688 static void 689 thread_reap_callout_cb(void *arg __unused) 690 { 691 struct thread_domain_data *tdd; 692 int i, cticks, lticks; 693 bool wantreap; 694 695 wantreap = false; 696 cticks = atomic_load_int(&ticks); 697 for (i = 0; i < vm_ndomains; i++) { 698 tdd = &thread_domain_data[i]; 699 lticks = tdd->tdd_reapticks; 700 if (tdd->tdd_zombies != NULL && 701 (u_int)(cticks - lticks) > 5 * hz) { 702 wantreap = true; 703 break; 704 } 705 } 706 707 if (wantreap) 708 taskqueue_enqueue(taskqueue_thread, &thread_reap_task); 709 callout_reset(&thread_reap_callout, 5 * hz, 710 thread_reap_callout_cb, NULL); 711 } 712 713 /* 714 * Calling this function guarantees that any thread that exited before 715 * the call is reaped when the function returns. By 'exited' we mean 716 * a thread removed from the process linkage with thread_unlink(). 717 * Practically this means that caller must lock/unlock corresponding 718 * process lock before the call, to synchronize with thread_exit(). 719 */ 720 void 721 thread_reap_barrier(void) 722 { 723 struct task *t; 724 725 /* 726 * First do context switches to each CPU to ensure that all 727 * PCPU pc_deadthreads are moved to zombie list. 728 */ 729 quiesce_all_cpus("", PDROP); 730 731 /* 732 * Second, fire the task in the same thread as normal 733 * thread_reap() is done, to serialize reaping. 734 */ 735 t = malloc(sizeof(*t), M_TEMP, M_WAITOK); 736 TASK_INIT(t, 0, thread_reap_task_cb, t); 737 taskqueue_enqueue(taskqueue_thread, t); 738 taskqueue_drain(taskqueue_thread, t); 739 free(t, M_TEMP); 740 } 741 742 /* 743 * Allocate a thread. 744 */ 745 struct thread * 746 thread_alloc(int pages) 747 { 748 struct thread *td; 749 lwpid_t tid; 750 751 if (!thread_count_inc()) { 752 return (NULL); 753 } 754 755 tid = tid_alloc(); 756 td = uma_zalloc(thread_zone, M_WAITOK); 757 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 758 if (!vm_thread_new(td, pages)) { 759 uma_zfree(thread_zone, td); 760 tid_free(tid); 761 thread_count_dec(); 762 return (NULL); 763 } 764 td->td_tid = tid; 765 bzero(&td->td_sa.args, sizeof(td->td_sa.args)); 766 kmsan_thread_alloc(td); 767 cpu_thread_alloc(td); 768 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); 769 return (td); 770 } 771 772 int 773 thread_alloc_stack(struct thread *td, int pages) 774 { 775 776 KASSERT(td->td_kstack == 0, 777 ("thread_alloc_stack called on a thread with kstack")); 778 if (!vm_thread_new(td, pages)) 779 return (0); 780 cpu_thread_alloc(td); 781 return (1); 782 } 783 784 /* 785 * Deallocate a thread. 786 */ 787 static void 788 thread_free_batched(struct thread *td) 789 { 790 791 lock_profile_thread_exit(td); 792 if (td->td_cpuset) 793 cpuset_rel(td->td_cpuset); 794 td->td_cpuset = NULL; 795 cpu_thread_free(td); 796 if (td->td_kstack != 0) 797 vm_thread_dispose(td); 798 callout_drain(&td->td_slpcallout); 799 /* 800 * Freeing handled by the caller. 801 */ 802 td->td_tid = -1; 803 kmsan_thread_free(td); 804 uma_zfree(thread_zone, td); 805 } 806 807 void 808 thread_free(struct thread *td) 809 { 810 lwpid_t tid; 811 812 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td); 813 tid = td->td_tid; 814 thread_free_batched(td); 815 tid_free(tid); 816 thread_count_dec(); 817 } 818 819 void 820 thread_cow_get_proc(struct thread *newtd, struct proc *p) 821 { 822 823 PROC_LOCK_ASSERT(p, MA_OWNED); 824 newtd->td_realucred = crcowget(p->p_ucred); 825 newtd->td_ucred = newtd->td_realucred; 826 newtd->td_limit = lim_hold(p->p_limit); 827 newtd->td_cowgen = p->p_cowgen; 828 } 829 830 void 831 thread_cow_get(struct thread *newtd, struct thread *td) 832 { 833 834 MPASS(td->td_realucred == td->td_ucred); 835 newtd->td_realucred = crcowget(td->td_realucred); 836 newtd->td_ucred = newtd->td_realucred; 837 newtd->td_limit = lim_hold(td->td_limit); 838 newtd->td_cowgen = td->td_cowgen; 839 } 840 841 void 842 thread_cow_free(struct thread *td) 843 { 844 845 if (td->td_realucred != NULL) 846 crcowfree(td); 847 if (td->td_limit != NULL) 848 lim_free(td->td_limit); 849 } 850 851 void 852 thread_cow_update(struct thread *td) 853 { 854 struct proc *p; 855 struct ucred *oldcred; 856 struct plimit *oldlimit; 857 858 p = td->td_proc; 859 oldlimit = NULL; 860 PROC_LOCK(p); 861 oldcred = crcowsync(); 862 oldlimit = lim_cowsync(); 863 td->td_cowgen = p->p_cowgen; 864 PROC_UNLOCK(p); 865 if (oldcred != NULL) 866 crfree(oldcred); 867 if (oldlimit != NULL) 868 lim_free(oldlimit); 869 } 870 871 void 872 thread_cow_synced(struct thread *td) 873 { 874 struct proc *p; 875 876 p = td->td_proc; 877 PROC_LOCK_ASSERT(p, MA_OWNED); 878 MPASS(td->td_cowgen != p->p_cowgen); 879 MPASS(td->td_ucred == p->p_ucred); 880 MPASS(td->td_limit == p->p_limit); 881 td->td_cowgen = p->p_cowgen; 882 } 883 884 /* 885 * Discard the current thread and exit from its context. 886 * Always called with scheduler locked. 887 * 888 * Because we can't free a thread while we're operating under its context, 889 * push the current thread into our CPU's deadthread holder. This means 890 * we needn't worry about someone else grabbing our context before we 891 * do a cpu_throw(). 892 */ 893 void 894 thread_exit(void) 895 { 896 uint64_t runtime, new_switchtime; 897 struct thread *td; 898 struct thread *td2; 899 struct proc *p; 900 int wakeup_swapper; 901 902 td = curthread; 903 p = td->td_proc; 904 905 PROC_SLOCK_ASSERT(p, MA_OWNED); 906 mtx_assert(&Giant, MA_NOTOWNED); 907 908 PROC_LOCK_ASSERT(p, MA_OWNED); 909 KASSERT(p != NULL, ("thread exiting without a process")); 910 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 911 (long)p->p_pid, td->td_name); 912 SDT_PROBE0(proc, , , lwp__exit); 913 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 914 MPASS(td->td_realucred == td->td_ucred); 915 916 /* 917 * drop FPU & debug register state storage, or any other 918 * architecture specific resources that 919 * would not be on a new untouched process. 920 */ 921 cpu_thread_exit(td); 922 923 /* 924 * The last thread is left attached to the process 925 * So that the whole bundle gets recycled. Skip 926 * all this stuff if we never had threads. 927 * EXIT clears all sign of other threads when 928 * it goes to single threading, so the last thread always 929 * takes the short path. 930 */ 931 if (p->p_flag & P_HADTHREADS) { 932 if (p->p_numthreads > 1) { 933 atomic_add_int(&td->td_proc->p_exitthreads, 1); 934 thread_unlink(td); 935 td2 = FIRST_THREAD_IN_PROC(p); 936 sched_exit_thread(td2, td); 937 938 /* 939 * The test below is NOT true if we are the 940 * sole exiting thread. P_STOPPED_SINGLE is unset 941 * in exit1() after it is the only survivor. 942 */ 943 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 944 if (p->p_numthreads == p->p_suspcount) { 945 thread_lock(p->p_singlethread); 946 wakeup_swapper = thread_unsuspend_one( 947 p->p_singlethread, p, false); 948 if (wakeup_swapper) 949 kick_proc0(); 950 } 951 } 952 953 PCPU_SET(deadthread, td); 954 } else { 955 /* 956 * The last thread is exiting.. but not through exit() 957 */ 958 panic ("thread_exit: Last thread exiting on its own"); 959 } 960 } 961 #ifdef HWPMC_HOOKS 962 /* 963 * If this thread is part of a process that is being tracked by hwpmc(4), 964 * inform the module of the thread's impending exit. 965 */ 966 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) { 967 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 968 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL); 969 } else if (PMC_SYSTEM_SAMPLING_ACTIVE()) 970 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL); 971 #endif 972 PROC_UNLOCK(p); 973 PROC_STATLOCK(p); 974 thread_lock(td); 975 PROC_SUNLOCK(p); 976 977 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 978 new_switchtime = cpu_ticks(); 979 runtime = new_switchtime - PCPU_GET(switchtime); 980 td->td_runtime += runtime; 981 td->td_incruntime += runtime; 982 PCPU_SET(switchtime, new_switchtime); 983 PCPU_SET(switchticks, ticks); 984 VM_CNT_INC(v_swtch); 985 986 /* Save our resource usage in our process. */ 987 td->td_ru.ru_nvcsw++; 988 ruxagg_locked(p, td); 989 rucollect(&p->p_ru, &td->td_ru); 990 PROC_STATUNLOCK(p); 991 992 TD_SET_STATE(td, TDS_INACTIVE); 993 #ifdef WITNESS 994 witness_thread_exit(td); 995 #endif 996 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 997 sched_throw(td); 998 panic("I'm a teapot!"); 999 /* NOTREACHED */ 1000 } 1001 1002 /* 1003 * Do any thread specific cleanups that may be needed in wait() 1004 * called with Giant, proc and schedlock not held. 1005 */ 1006 void 1007 thread_wait(struct proc *p) 1008 { 1009 struct thread *td; 1010 1011 mtx_assert(&Giant, MA_NOTOWNED); 1012 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 1013 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 1014 td = FIRST_THREAD_IN_PROC(p); 1015 /* Lock the last thread so we spin until it exits cpu_throw(). */ 1016 thread_lock(td); 1017 thread_unlock(td); 1018 lock_profile_thread_exit(td); 1019 cpuset_rel(td->td_cpuset); 1020 td->td_cpuset = NULL; 1021 cpu_thread_clean(td); 1022 thread_cow_free(td); 1023 callout_drain(&td->td_slpcallout); 1024 thread_reap(); /* check for zombie threads etc. */ 1025 } 1026 1027 /* 1028 * Link a thread to a process. 1029 * set up anything that needs to be initialized for it to 1030 * be used by the process. 1031 */ 1032 void 1033 thread_link(struct thread *td, struct proc *p) 1034 { 1035 1036 /* 1037 * XXX This can't be enabled because it's called for proc0 before 1038 * its lock has been created. 1039 * PROC_LOCK_ASSERT(p, MA_OWNED); 1040 */ 1041 TD_SET_STATE(td, TDS_INACTIVE); 1042 td->td_proc = p; 1043 td->td_flags = TDF_INMEM; 1044 1045 LIST_INIT(&td->td_contested); 1046 LIST_INIT(&td->td_lprof[0]); 1047 LIST_INIT(&td->td_lprof[1]); 1048 #ifdef EPOCH_TRACE 1049 SLIST_INIT(&td->td_epochs); 1050 #endif 1051 sigqueue_init(&td->td_sigqueue, p); 1052 callout_init(&td->td_slpcallout, 1); 1053 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 1054 p->p_numthreads++; 1055 } 1056 1057 /* 1058 * Called from: 1059 * thread_exit() 1060 */ 1061 void 1062 thread_unlink(struct thread *td) 1063 { 1064 struct proc *p = td->td_proc; 1065 1066 PROC_LOCK_ASSERT(p, MA_OWNED); 1067 #ifdef EPOCH_TRACE 1068 MPASS(SLIST_EMPTY(&td->td_epochs)); 1069 #endif 1070 1071 TAILQ_REMOVE(&p->p_threads, td, td_plist); 1072 p->p_numthreads--; 1073 /* could clear a few other things here */ 1074 /* Must NOT clear links to proc! */ 1075 } 1076 1077 static int 1078 calc_remaining(struct proc *p, int mode) 1079 { 1080 int remaining; 1081 1082 PROC_LOCK_ASSERT(p, MA_OWNED); 1083 PROC_SLOCK_ASSERT(p, MA_OWNED); 1084 if (mode == SINGLE_EXIT) 1085 remaining = p->p_numthreads; 1086 else if (mode == SINGLE_BOUNDARY) 1087 remaining = p->p_numthreads - p->p_boundary_count; 1088 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 1089 remaining = p->p_numthreads - p->p_suspcount; 1090 else 1091 panic("calc_remaining: wrong mode %d", mode); 1092 return (remaining); 1093 } 1094 1095 static int 1096 remain_for_mode(int mode) 1097 { 1098 1099 return (mode == SINGLE_ALLPROC ? 0 : 1); 1100 } 1101 1102 static int 1103 weed_inhib(int mode, struct thread *td2, struct proc *p) 1104 { 1105 int wakeup_swapper; 1106 1107 PROC_LOCK_ASSERT(p, MA_OWNED); 1108 PROC_SLOCK_ASSERT(p, MA_OWNED); 1109 THREAD_LOCK_ASSERT(td2, MA_OWNED); 1110 1111 wakeup_swapper = 0; 1112 1113 /* 1114 * Since the thread lock is dropped by the scheduler we have 1115 * to retry to check for races. 1116 */ 1117 restart: 1118 switch (mode) { 1119 case SINGLE_EXIT: 1120 if (TD_IS_SUSPENDED(td2)) { 1121 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 1122 thread_lock(td2); 1123 goto restart; 1124 } 1125 if (TD_CAN_ABORT(td2)) { 1126 wakeup_swapper |= sleepq_abort(td2, EINTR); 1127 return (wakeup_swapper); 1128 } 1129 break; 1130 case SINGLE_BOUNDARY: 1131 case SINGLE_NO_EXIT: 1132 if (TD_IS_SUSPENDED(td2) && 1133 (td2->td_flags & TDF_BOUNDARY) == 0) { 1134 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 1135 thread_lock(td2); 1136 goto restart; 1137 } 1138 if (TD_CAN_ABORT(td2)) { 1139 wakeup_swapper |= sleepq_abort(td2, ERESTART); 1140 return (wakeup_swapper); 1141 } 1142 break; 1143 case SINGLE_ALLPROC: 1144 /* 1145 * ALLPROC suspend tries to avoid spurious EINTR for 1146 * threads sleeping interruptable, by suspending the 1147 * thread directly, similarly to sig_suspend_threads(). 1148 * Since such sleep is not performed at the user 1149 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 1150 * is used to avoid immediate un-suspend. 1151 */ 1152 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 1153 TDF_ALLPROCSUSP)) == 0) { 1154 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 1155 thread_lock(td2); 1156 goto restart; 1157 } 1158 if (TD_CAN_ABORT(td2)) { 1159 if ((td2->td_flags & TDF_SBDRY) == 0) { 1160 thread_suspend_one(td2); 1161 td2->td_flags |= TDF_ALLPROCSUSP; 1162 } else { 1163 wakeup_swapper |= sleepq_abort(td2, ERESTART); 1164 return (wakeup_swapper); 1165 } 1166 } 1167 break; 1168 default: 1169 break; 1170 } 1171 thread_unlock(td2); 1172 return (wakeup_swapper); 1173 } 1174 1175 /* 1176 * Enforce single-threading. 1177 * 1178 * Returns 1 if the caller must abort (another thread is waiting to 1179 * exit the process or similar). Process is locked! 1180 * Returns 0 when you are successfully the only thread running. 1181 * A process has successfully single threaded in the suspend mode when 1182 * There are no threads in user mode. Threads in the kernel must be 1183 * allowed to continue until they get to the user boundary. They may even 1184 * copy out their return values and data before suspending. They may however be 1185 * accelerated in reaching the user boundary as we will wake up 1186 * any sleeping threads that are interruptable. (PCATCH). 1187 */ 1188 int 1189 thread_single(struct proc *p, int mode) 1190 { 1191 struct thread *td; 1192 struct thread *td2; 1193 int remaining, wakeup_swapper; 1194 1195 td = curthread; 1196 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1197 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1198 ("invalid mode %d", mode)); 1199 /* 1200 * If allowing non-ALLPROC singlethreading for non-curproc 1201 * callers, calc_remaining() and remain_for_mode() should be 1202 * adjusted to also account for td->td_proc != p. For now 1203 * this is not implemented because it is not used. 1204 */ 1205 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 1206 (mode != SINGLE_ALLPROC && td->td_proc == p), 1207 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 1208 mtx_assert(&Giant, MA_NOTOWNED); 1209 PROC_LOCK_ASSERT(p, MA_OWNED); 1210 1211 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 1212 return (0); 1213 1214 /* Is someone already single threading? */ 1215 if (p->p_singlethread != NULL && p->p_singlethread != td) 1216 return (1); 1217 1218 if (mode == SINGLE_EXIT) { 1219 p->p_flag |= P_SINGLE_EXIT; 1220 p->p_flag &= ~P_SINGLE_BOUNDARY; 1221 } else { 1222 p->p_flag &= ~P_SINGLE_EXIT; 1223 if (mode == SINGLE_BOUNDARY) 1224 p->p_flag |= P_SINGLE_BOUNDARY; 1225 else 1226 p->p_flag &= ~P_SINGLE_BOUNDARY; 1227 } 1228 if (mode == SINGLE_ALLPROC) 1229 p->p_flag |= P_TOTAL_STOP; 1230 p->p_flag |= P_STOPPED_SINGLE; 1231 PROC_SLOCK(p); 1232 p->p_singlethread = td; 1233 remaining = calc_remaining(p, mode); 1234 while (remaining != remain_for_mode(mode)) { 1235 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 1236 goto stopme; 1237 wakeup_swapper = 0; 1238 FOREACH_THREAD_IN_PROC(p, td2) { 1239 if (td2 == td) 1240 continue; 1241 thread_lock(td2); 1242 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 1243 if (TD_IS_INHIBITED(td2)) { 1244 wakeup_swapper |= weed_inhib(mode, td2, p); 1245 #ifdef SMP 1246 } else if (TD_IS_RUNNING(td2) && td != td2) { 1247 forward_signal(td2); 1248 thread_unlock(td2); 1249 #endif 1250 } else 1251 thread_unlock(td2); 1252 } 1253 if (wakeup_swapper) 1254 kick_proc0(); 1255 remaining = calc_remaining(p, mode); 1256 1257 /* 1258 * Maybe we suspended some threads.. was it enough? 1259 */ 1260 if (remaining == remain_for_mode(mode)) 1261 break; 1262 1263 stopme: 1264 /* 1265 * Wake us up when everyone else has suspended. 1266 * In the mean time we suspend as well. 1267 */ 1268 thread_suspend_switch(td, p); 1269 remaining = calc_remaining(p, mode); 1270 } 1271 if (mode == SINGLE_EXIT) { 1272 /* 1273 * Convert the process to an unthreaded process. The 1274 * SINGLE_EXIT is called by exit1() or execve(), in 1275 * both cases other threads must be retired. 1276 */ 1277 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 1278 p->p_singlethread = NULL; 1279 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 1280 1281 /* 1282 * Wait for any remaining threads to exit cpu_throw(). 1283 */ 1284 while (p->p_exitthreads != 0) { 1285 PROC_SUNLOCK(p); 1286 PROC_UNLOCK(p); 1287 sched_relinquish(td); 1288 PROC_LOCK(p); 1289 PROC_SLOCK(p); 1290 } 1291 } else if (mode == SINGLE_BOUNDARY) { 1292 /* 1293 * Wait until all suspended threads are removed from 1294 * the processors. The thread_suspend_check() 1295 * increments p_boundary_count while it is still 1296 * running, which makes it possible for the execve() 1297 * to destroy vmspace while our other threads are 1298 * still using the address space. 1299 * 1300 * We lock the thread, which is only allowed to 1301 * succeed after context switch code finished using 1302 * the address space. 1303 */ 1304 FOREACH_THREAD_IN_PROC(p, td2) { 1305 if (td2 == td) 1306 continue; 1307 thread_lock(td2); 1308 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 1309 ("td %p not on boundary", td2)); 1310 KASSERT(TD_IS_SUSPENDED(td2), 1311 ("td %p is not suspended", td2)); 1312 thread_unlock(td2); 1313 } 1314 } 1315 PROC_SUNLOCK(p); 1316 return (0); 1317 } 1318 1319 bool 1320 thread_suspend_check_needed(void) 1321 { 1322 struct proc *p; 1323 struct thread *td; 1324 1325 td = curthread; 1326 p = td->td_proc; 1327 PROC_LOCK_ASSERT(p, MA_OWNED); 1328 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 1329 (td->td_dbgflags & TDB_SUSPEND) != 0)); 1330 } 1331 1332 /* 1333 * Called in from locations that can safely check to see 1334 * whether we have to suspend or at least throttle for a 1335 * single-thread event (e.g. fork). 1336 * 1337 * Such locations include userret(). 1338 * If the "return_instead" argument is non zero, the thread must be able to 1339 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 1340 * 1341 * The 'return_instead' argument tells the function if it may do a 1342 * thread_exit() or suspend, or whether the caller must abort and back 1343 * out instead. 1344 * 1345 * If the thread that set the single_threading request has set the 1346 * P_SINGLE_EXIT bit in the process flags then this call will never return 1347 * if 'return_instead' is false, but will exit. 1348 * 1349 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 1350 *---------------+--------------------+--------------------- 1351 * 0 | returns 0 | returns 0 or 1 1352 * | when ST ends | immediately 1353 *---------------+--------------------+--------------------- 1354 * 1 | thread exits | returns 1 1355 * | | immediately 1356 * 0 = thread_exit() or suspension ok, 1357 * other = return error instead of stopping the thread. 1358 * 1359 * While a full suspension is under effect, even a single threading 1360 * thread would be suspended if it made this call (but it shouldn't). 1361 * This call should only be made from places where 1362 * thread_exit() would be safe as that may be the outcome unless 1363 * return_instead is set. 1364 */ 1365 int 1366 thread_suspend_check(int return_instead) 1367 { 1368 struct thread *td; 1369 struct proc *p; 1370 int wakeup_swapper; 1371 1372 td = curthread; 1373 p = td->td_proc; 1374 mtx_assert(&Giant, MA_NOTOWNED); 1375 PROC_LOCK_ASSERT(p, MA_OWNED); 1376 while (thread_suspend_check_needed()) { 1377 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1378 KASSERT(p->p_singlethread != NULL, 1379 ("singlethread not set")); 1380 /* 1381 * The only suspension in action is a 1382 * single-threading. Single threader need not stop. 1383 * It is safe to access p->p_singlethread unlocked 1384 * because it can only be set to our address by us. 1385 */ 1386 if (p->p_singlethread == td) 1387 return (0); /* Exempt from stopping. */ 1388 } 1389 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 1390 return (EINTR); 1391 1392 /* Should we goto user boundary if we didn't come from there? */ 1393 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1394 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 1395 return (ERESTART); 1396 1397 /* 1398 * Ignore suspend requests if they are deferred. 1399 */ 1400 if ((td->td_flags & TDF_SBDRY) != 0) { 1401 KASSERT(return_instead, 1402 ("TDF_SBDRY set for unsafe thread_suspend_check")); 1403 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 1404 (TDF_SEINTR | TDF_SERESTART), 1405 ("both TDF_SEINTR and TDF_SERESTART")); 1406 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 1407 } 1408 1409 /* 1410 * If the process is waiting for us to exit, 1411 * this thread should just suicide. 1412 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 1413 */ 1414 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 1415 PROC_UNLOCK(p); 1416 1417 /* 1418 * Allow Linux emulation layer to do some work 1419 * before thread suicide. 1420 */ 1421 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 1422 (p->p_sysent->sv_thread_detach)(td); 1423 umtx_thread_exit(td); 1424 kern_thr_exit(td); 1425 panic("stopped thread did not exit"); 1426 } 1427 1428 PROC_SLOCK(p); 1429 thread_stopped(p); 1430 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1431 if (p->p_numthreads == p->p_suspcount + 1) { 1432 thread_lock(p->p_singlethread); 1433 wakeup_swapper = thread_unsuspend_one( 1434 p->p_singlethread, p, false); 1435 if (wakeup_swapper) 1436 kick_proc0(); 1437 } 1438 } 1439 PROC_UNLOCK(p); 1440 thread_lock(td); 1441 /* 1442 * When a thread suspends, it just 1443 * gets taken off all queues. 1444 */ 1445 thread_suspend_one(td); 1446 if (return_instead == 0) { 1447 p->p_boundary_count++; 1448 td->td_flags |= TDF_BOUNDARY; 1449 } 1450 PROC_SUNLOCK(p); 1451 mi_switch(SW_INVOL | SWT_SUSPEND); 1452 PROC_LOCK(p); 1453 } 1454 return (0); 1455 } 1456 1457 /* 1458 * Check for possible stops and suspensions while executing a 1459 * casueword or similar transiently failing operation. 1460 * 1461 * The sleep argument controls whether the function can handle a stop 1462 * request itself or it should return ERESTART and the request is 1463 * proceed at the kernel/user boundary in ast. 1464 * 1465 * Typically, when retrying due to casueword(9) failure (rv == 1), we 1466 * should handle the stop requests there, with exception of cases when 1467 * the thread owns a kernel resource, for instance busied the umtx 1468 * key, or when functions return immediately if thread_check_susp() 1469 * returned non-zero. On the other hand, retrying the whole lock 1470 * operation, we better not stop there but delegate the handling to 1471 * ast. 1472 * 1473 * If the request is for thread termination P_SINGLE_EXIT, we cannot 1474 * handle it at all, and simply return EINTR. 1475 */ 1476 int 1477 thread_check_susp(struct thread *td, bool sleep) 1478 { 1479 struct proc *p; 1480 int error; 1481 1482 /* 1483 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to 1484 * eventually break the lockstep loop. 1485 */ 1486 if ((td->td_flags & TDF_NEEDSUSPCHK) == 0) 1487 return (0); 1488 error = 0; 1489 p = td->td_proc; 1490 PROC_LOCK(p); 1491 if (p->p_flag & P_SINGLE_EXIT) 1492 error = EINTR; 1493 else if (P_SHOULDSTOP(p) || 1494 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) 1495 error = sleep ? thread_suspend_check(0) : ERESTART; 1496 PROC_UNLOCK(p); 1497 return (error); 1498 } 1499 1500 void 1501 thread_suspend_switch(struct thread *td, struct proc *p) 1502 { 1503 1504 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1505 PROC_LOCK_ASSERT(p, MA_OWNED); 1506 PROC_SLOCK_ASSERT(p, MA_OWNED); 1507 /* 1508 * We implement thread_suspend_one in stages here to avoid 1509 * dropping the proc lock while the thread lock is owned. 1510 */ 1511 if (p == td->td_proc) { 1512 thread_stopped(p); 1513 p->p_suspcount++; 1514 } 1515 PROC_UNLOCK(p); 1516 thread_lock(td); 1517 td->td_flags &= ~TDF_NEEDSUSPCHK; 1518 TD_SET_SUSPENDED(td); 1519 sched_sleep(td, 0); 1520 PROC_SUNLOCK(p); 1521 DROP_GIANT(); 1522 mi_switch(SW_VOL | SWT_SUSPEND); 1523 PICKUP_GIANT(); 1524 PROC_LOCK(p); 1525 PROC_SLOCK(p); 1526 } 1527 1528 void 1529 thread_suspend_one(struct thread *td) 1530 { 1531 struct proc *p; 1532 1533 p = td->td_proc; 1534 PROC_SLOCK_ASSERT(p, MA_OWNED); 1535 THREAD_LOCK_ASSERT(td, MA_OWNED); 1536 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1537 p->p_suspcount++; 1538 td->td_flags &= ~TDF_NEEDSUSPCHK; 1539 TD_SET_SUSPENDED(td); 1540 sched_sleep(td, 0); 1541 } 1542 1543 static int 1544 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1545 { 1546 1547 THREAD_LOCK_ASSERT(td, MA_OWNED); 1548 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1549 TD_CLR_SUSPENDED(td); 1550 td->td_flags &= ~TDF_ALLPROCSUSP; 1551 if (td->td_proc == p) { 1552 PROC_SLOCK_ASSERT(p, MA_OWNED); 1553 p->p_suspcount--; 1554 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1555 td->td_flags &= ~TDF_BOUNDARY; 1556 p->p_boundary_count--; 1557 } 1558 } 1559 return (setrunnable(td, 0)); 1560 } 1561 1562 void 1563 thread_run_flash(struct thread *td) 1564 { 1565 struct proc *p; 1566 1567 p = td->td_proc; 1568 PROC_LOCK_ASSERT(p, MA_OWNED); 1569 1570 if (TD_ON_SLEEPQ(td)) 1571 sleepq_remove_nested(td); 1572 else 1573 thread_lock(td); 1574 1575 THREAD_LOCK_ASSERT(td, MA_OWNED); 1576 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1577 1578 TD_CLR_SUSPENDED(td); 1579 PROC_SLOCK(p); 1580 MPASS(p->p_suspcount > 0); 1581 p->p_suspcount--; 1582 PROC_SUNLOCK(p); 1583 if (setrunnable(td, 0)) 1584 kick_proc0(); 1585 } 1586 1587 /* 1588 * Allow all threads blocked by single threading to continue running. 1589 */ 1590 void 1591 thread_unsuspend(struct proc *p) 1592 { 1593 struct thread *td; 1594 int wakeup_swapper; 1595 1596 PROC_LOCK_ASSERT(p, MA_OWNED); 1597 PROC_SLOCK_ASSERT(p, MA_OWNED); 1598 wakeup_swapper = 0; 1599 if (!P_SHOULDSTOP(p)) { 1600 FOREACH_THREAD_IN_PROC(p, td) { 1601 thread_lock(td); 1602 if (TD_IS_SUSPENDED(td)) { 1603 wakeup_swapper |= thread_unsuspend_one(td, p, 1604 true); 1605 } else 1606 thread_unlock(td); 1607 } 1608 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1609 p->p_numthreads == p->p_suspcount) { 1610 /* 1611 * Stopping everything also did the job for the single 1612 * threading request. Now we've downgraded to single-threaded, 1613 * let it continue. 1614 */ 1615 if (p->p_singlethread->td_proc == p) { 1616 thread_lock(p->p_singlethread); 1617 wakeup_swapper = thread_unsuspend_one( 1618 p->p_singlethread, p, false); 1619 } 1620 } 1621 if (wakeup_swapper) 1622 kick_proc0(); 1623 } 1624 1625 /* 1626 * End the single threading mode.. 1627 */ 1628 void 1629 thread_single_end(struct proc *p, int mode) 1630 { 1631 struct thread *td; 1632 int wakeup_swapper; 1633 1634 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1635 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1636 ("invalid mode %d", mode)); 1637 PROC_LOCK_ASSERT(p, MA_OWNED); 1638 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1639 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1640 ("mode %d does not match P_TOTAL_STOP", mode)); 1641 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1642 ("thread_single_end from other thread %p %p", 1643 curthread, p->p_singlethread)); 1644 KASSERT(mode != SINGLE_BOUNDARY || 1645 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1646 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1647 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1648 P_TOTAL_STOP); 1649 PROC_SLOCK(p); 1650 p->p_singlethread = NULL; 1651 wakeup_swapper = 0; 1652 /* 1653 * If there are other threads they may now run, 1654 * unless of course there is a blanket 'stop order' 1655 * on the process. The single threader must be allowed 1656 * to continue however as this is a bad place to stop. 1657 */ 1658 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1659 FOREACH_THREAD_IN_PROC(p, td) { 1660 thread_lock(td); 1661 if (TD_IS_SUSPENDED(td)) { 1662 wakeup_swapper |= thread_unsuspend_one(td, p, 1663 mode == SINGLE_BOUNDARY); 1664 } else 1665 thread_unlock(td); 1666 } 1667 } 1668 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1669 ("inconsistent boundary count %d", p->p_boundary_count)); 1670 PROC_SUNLOCK(p); 1671 if (wakeup_swapper) 1672 kick_proc0(); 1673 } 1674 1675 /* 1676 * Locate a thread by number and return with proc lock held. 1677 * 1678 * thread exit establishes proc -> tidhash lock ordering, but lookup 1679 * takes tidhash first and needs to return locked proc. 1680 * 1681 * The problem is worked around by relying on type-safety of both 1682 * structures and doing the work in 2 steps: 1683 * - tidhash-locked lookup which saves both thread and proc pointers 1684 * - proc-locked verification that the found thread still matches 1685 */ 1686 static bool 1687 tdfind_hash(lwpid_t tid, pid_t pid, struct proc **pp, struct thread **tdp) 1688 { 1689 #define RUN_THRESH 16 1690 struct proc *p; 1691 struct thread *td; 1692 int run; 1693 bool locked; 1694 1695 run = 0; 1696 rw_rlock(TIDHASHLOCK(tid)); 1697 locked = true; 1698 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1699 if (td->td_tid != tid) { 1700 run++; 1701 continue; 1702 } 1703 p = td->td_proc; 1704 if (pid != -1 && p->p_pid != pid) { 1705 td = NULL; 1706 break; 1707 } 1708 if (run > RUN_THRESH) { 1709 if (rw_try_upgrade(TIDHASHLOCK(tid))) { 1710 LIST_REMOVE(td, td_hash); 1711 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1712 td, td_hash); 1713 rw_wunlock(TIDHASHLOCK(tid)); 1714 locked = false; 1715 break; 1716 } 1717 } 1718 break; 1719 } 1720 if (locked) 1721 rw_runlock(TIDHASHLOCK(tid)); 1722 if (td == NULL) 1723 return (false); 1724 *pp = p; 1725 *tdp = td; 1726 return (true); 1727 } 1728 1729 struct thread * 1730 tdfind(lwpid_t tid, pid_t pid) 1731 { 1732 struct proc *p; 1733 struct thread *td; 1734 1735 td = curthread; 1736 if (td->td_tid == tid) { 1737 if (pid != -1 && td->td_proc->p_pid != pid) 1738 return (NULL); 1739 PROC_LOCK(td->td_proc); 1740 return (td); 1741 } 1742 1743 for (;;) { 1744 if (!tdfind_hash(tid, pid, &p, &td)) 1745 return (NULL); 1746 PROC_LOCK(p); 1747 if (td->td_tid != tid) { 1748 PROC_UNLOCK(p); 1749 continue; 1750 } 1751 if (td->td_proc != p) { 1752 PROC_UNLOCK(p); 1753 continue; 1754 } 1755 if (p->p_state == PRS_NEW) { 1756 PROC_UNLOCK(p); 1757 return (NULL); 1758 } 1759 return (td); 1760 } 1761 } 1762 1763 void 1764 tidhash_add(struct thread *td) 1765 { 1766 rw_wlock(TIDHASHLOCK(td->td_tid)); 1767 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1768 rw_wunlock(TIDHASHLOCK(td->td_tid)); 1769 } 1770 1771 void 1772 tidhash_remove(struct thread *td) 1773 { 1774 1775 rw_wlock(TIDHASHLOCK(td->td_tid)); 1776 LIST_REMOVE(td, td_hash); 1777 rw_wunlock(TIDHASHLOCK(td->td_tid)); 1778 } 1779