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/mutex.h> 42 #include <sys/proc.h> 43 #include <sys/bitstring.h> 44 #include <sys/epoch.h> 45 #include <sys/rangelock.h> 46 #include <sys/resourcevar.h> 47 #include <sys/sdt.h> 48 #include <sys/smp.h> 49 #include <sys/sched.h> 50 #include <sys/sleepqueue.h> 51 #include <sys/selinfo.h> 52 #include <sys/syscallsubr.h> 53 #include <sys/sysent.h> 54 #include <sys/turnstile.h> 55 #include <sys/ktr.h> 56 #include <sys/rwlock.h> 57 #include <sys/umtx.h> 58 #include <sys/vmmeter.h> 59 #include <sys/cpuset.h> 60 #ifdef HWPMC_HOOKS 61 #include <sys/pmckern.h> 62 #endif 63 #include <sys/priv.h> 64 65 #include <security/audit/audit.h> 66 67 #include <vm/vm.h> 68 #include <vm/vm_extern.h> 69 #include <vm/uma.h> 70 #include <sys/eventhandler.h> 71 72 /* 73 * Asserts below verify the stability of struct thread and struct proc 74 * layout, as exposed by KBI to modules. On head, the KBI is allowed 75 * to drift, change to the structures must be accompanied by the 76 * assert update. 77 * 78 * On the stable branches after KBI freeze, conditions must not be 79 * violated. Typically new fields are moved to the end of the 80 * structures. 81 */ 82 #ifdef __amd64__ 83 _Static_assert(offsetof(struct thread, td_flags) == 0xfc, 84 "struct thread KBI td_flags"); 85 _Static_assert(offsetof(struct thread, td_pflags) == 0x104, 86 "struct thread KBI td_pflags"); 87 _Static_assert(offsetof(struct thread, td_frame) == 0x4a0, 88 "struct thread KBI td_frame"); 89 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6b0, 90 "struct thread KBI td_emuldata"); 91 _Static_assert(offsetof(struct proc, p_flag) == 0xb8, 92 "struct proc KBI p_flag"); 93 _Static_assert(offsetof(struct proc, p_pid) == 0xc4, 94 "struct proc KBI p_pid"); 95 _Static_assert(offsetof(struct proc, p_filemon) == 0x3c0, 96 "struct proc KBI p_filemon"); 97 _Static_assert(offsetof(struct proc, p_comm) == 0x3d8, 98 "struct proc KBI p_comm"); 99 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4b8, 100 "struct proc KBI p_emuldata"); 101 #endif 102 #ifdef __i386__ 103 _Static_assert(offsetof(struct thread, td_flags) == 0x98, 104 "struct thread KBI td_flags"); 105 _Static_assert(offsetof(struct thread, td_pflags) == 0xa0, 106 "struct thread KBI td_pflags"); 107 _Static_assert(offsetof(struct thread, td_frame) == 0x300, 108 "struct thread KBI td_frame"); 109 _Static_assert(offsetof(struct thread, td_emuldata) == 0x344, 110 "struct thread KBI td_emuldata"); 111 _Static_assert(offsetof(struct proc, p_flag) == 0x6c, 112 "struct proc KBI p_flag"); 113 _Static_assert(offsetof(struct proc, p_pid) == 0x78, 114 "struct proc KBI p_pid"); 115 _Static_assert(offsetof(struct proc, p_filemon) == 0x26c, 116 "struct proc KBI p_filemon"); 117 _Static_assert(offsetof(struct proc, p_comm) == 0x280, 118 "struct proc KBI p_comm"); 119 _Static_assert(offsetof(struct proc, p_emuldata) == 0x30c, 120 "struct proc KBI p_emuldata"); 121 #endif 122 123 SDT_PROVIDER_DECLARE(proc); 124 SDT_PROBE_DEFINE(proc, , , lwp__exit); 125 126 /* 127 * thread related storage. 128 */ 129 static uma_zone_t thread_zone; 130 131 static __exclusive_cache_line struct thread *thread_zombies; 132 133 static void thread_zombie(struct thread *); 134 static int thread_unsuspend_one(struct thread *td, struct proc *p, 135 bool boundary); 136 static void thread_free_batched(struct thread *td); 137 138 static __exclusive_cache_line struct mtx tid_lock; 139 static bitstr_t *tid_bitmap; 140 141 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 142 143 static int maxthread; 144 SYSCTL_INT(_kern, OID_AUTO, maxthread, CTLFLAG_RDTUN, 145 &maxthread, 0, "Maximum number of threads"); 146 147 static __exclusive_cache_line int nthreads; 148 149 static LIST_HEAD(tidhashhead, thread) *tidhashtbl; 150 static u_long tidhash; 151 static u_long tidhashlock; 152 static struct rwlock *tidhashtbl_lock; 153 #define TIDHASH(tid) (&tidhashtbl[(tid) & tidhash]) 154 #define TIDHASHLOCK(tid) (&tidhashtbl_lock[(tid) & tidhashlock]) 155 156 EVENTHANDLER_LIST_DEFINE(thread_ctor); 157 EVENTHANDLER_LIST_DEFINE(thread_dtor); 158 EVENTHANDLER_LIST_DEFINE(thread_init); 159 EVENTHANDLER_LIST_DEFINE(thread_fini); 160 161 static bool 162 thread_count_inc(void) 163 { 164 static struct timeval lastfail; 165 static int curfail; 166 int nthreads_new; 167 168 thread_reap(); 169 170 nthreads_new = atomic_fetchadd_int(&nthreads, 1) + 1; 171 if (nthreads_new >= maxthread - 100) { 172 if (priv_check_cred(curthread->td_ucred, PRIV_MAXPROC) != 0 || 173 nthreads_new >= maxthread) { 174 atomic_subtract_int(&nthreads, 1); 175 if (ppsratecheck(&lastfail, &curfail, 1)) { 176 printf("maxthread limit exceeded by uid %u " 177 "(pid %d); consider increasing kern.maxthread\n", 178 curthread->td_ucred->cr_ruid, curproc->p_pid); 179 } 180 return (false); 181 } 182 } 183 return (true); 184 } 185 186 static void 187 thread_count_sub(int n) 188 { 189 190 atomic_subtract_int(&nthreads, n); 191 } 192 193 static void 194 thread_count_dec(void) 195 { 196 197 thread_count_sub(1); 198 } 199 200 static lwpid_t 201 tid_alloc(void) 202 { 203 static lwpid_t trytid; 204 lwpid_t tid; 205 206 mtx_lock(&tid_lock); 207 /* 208 * It is an invariant that the bitmap is big enough to hold maxthread 209 * IDs. If we got to this point there has to be at least one free. 210 */ 211 if (trytid >= maxthread) 212 trytid = 0; 213 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 214 if (tid == -1) { 215 KASSERT(trytid != 0, ("unexpectedly ran out of IDs")); 216 trytid = 0; 217 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 218 KASSERT(tid != -1, ("unexpectedly ran out of IDs")); 219 } 220 bit_set(tid_bitmap, tid); 221 trytid = tid + 1; 222 mtx_unlock(&tid_lock); 223 return (tid + NO_PID); 224 } 225 226 static void 227 tid_free_locked(lwpid_t rtid) 228 { 229 lwpid_t tid; 230 231 mtx_assert(&tid_lock, MA_OWNED); 232 KASSERT(rtid >= NO_PID, 233 ("%s: invalid tid %d\n", __func__, rtid)); 234 tid = rtid - NO_PID; 235 KASSERT(bit_test(tid_bitmap, tid) != 0, 236 ("thread ID %d not allocated\n", rtid)); 237 bit_clear(tid_bitmap, tid); 238 } 239 240 static void 241 tid_free(lwpid_t rtid) 242 { 243 244 mtx_lock(&tid_lock); 245 tid_free_locked(rtid); 246 mtx_unlock(&tid_lock); 247 } 248 249 static void 250 tid_free_batch(lwpid_t *batch, int n) 251 { 252 int i; 253 254 mtx_lock(&tid_lock); 255 for (i = 0; i < n; i++) { 256 tid_free_locked(batch[i]); 257 } 258 mtx_unlock(&tid_lock); 259 } 260 261 /* 262 * Batching for thread reapping. 263 */ 264 struct tidbatch { 265 lwpid_t tab[16]; 266 int n; 267 }; 268 269 static void 270 tidbatch_prep(struct tidbatch *tb) 271 { 272 273 tb->n = 0; 274 } 275 276 static void 277 tidbatch_add(struct tidbatch *tb, struct thread *td) 278 { 279 280 KASSERT(tb->n < nitems(tb->tab), 281 ("%s: count too high %d", __func__, tb->n)); 282 tb->tab[tb->n] = td->td_tid; 283 tb->n++; 284 } 285 286 static void 287 tidbatch_process(struct tidbatch *tb) 288 { 289 290 KASSERT(tb->n <= nitems(tb->tab), 291 ("%s: count too high %d", __func__, tb->n)); 292 if (tb->n == nitems(tb->tab)) { 293 tid_free_batch(tb->tab, tb->n); 294 tb->n = 0; 295 } 296 } 297 298 static void 299 tidbatch_final(struct tidbatch *tb) 300 { 301 302 KASSERT(tb->n <= nitems(tb->tab), 303 ("%s: count too high %d", __func__, tb->n)); 304 if (tb->n != 0) { 305 tid_free_batch(tb->tab, tb->n); 306 } 307 } 308 309 /* 310 * Prepare a thread for use. 311 */ 312 static int 313 thread_ctor(void *mem, int size, void *arg, int flags) 314 { 315 struct thread *td; 316 317 td = (struct thread *)mem; 318 td->td_state = TDS_INACTIVE; 319 td->td_lastcpu = td->td_oncpu = NOCPU; 320 321 /* 322 * Note that td_critnest begins life as 1 because the thread is not 323 * running and is thereby implicitly waiting to be on the receiving 324 * end of a context switch. 325 */ 326 td->td_critnest = 1; 327 td->td_lend_user_pri = PRI_MAX; 328 #ifdef AUDIT 329 audit_thread_alloc(td); 330 #endif 331 umtx_thread_alloc(td); 332 MPASS(td->td_sel == NULL); 333 return (0); 334 } 335 336 /* 337 * Reclaim a thread after use. 338 */ 339 static void 340 thread_dtor(void *mem, int size, void *arg) 341 { 342 struct thread *td; 343 344 td = (struct thread *)mem; 345 346 #ifdef INVARIANTS 347 /* Verify that this thread is in a safe state to free. */ 348 switch (td->td_state) { 349 case TDS_INHIBITED: 350 case TDS_RUNNING: 351 case TDS_CAN_RUN: 352 case TDS_RUNQ: 353 /* 354 * We must never unlink a thread that is in one of 355 * these states, because it is currently active. 356 */ 357 panic("bad state for thread unlinking"); 358 /* NOTREACHED */ 359 case TDS_INACTIVE: 360 break; 361 default: 362 panic("bad thread state"); 363 /* NOTREACHED */ 364 } 365 #endif 366 #ifdef AUDIT 367 audit_thread_free(td); 368 #endif 369 /* Free all OSD associated to this thread. */ 370 osd_thread_exit(td); 371 td_softdep_cleanup(td); 372 MPASS(td->td_su == NULL); 373 seltdfini(td); 374 } 375 376 /* 377 * Initialize type-stable parts of a thread (when newly created). 378 */ 379 static int 380 thread_init(void *mem, int size, int flags) 381 { 382 struct thread *td; 383 384 td = (struct thread *)mem; 385 386 td->td_sleepqueue = sleepq_alloc(); 387 td->td_turnstile = turnstile_alloc(); 388 td->td_rlqe = NULL; 389 EVENTHANDLER_DIRECT_INVOKE(thread_init, td); 390 umtx_thread_init(td); 391 td->td_kstack = 0; 392 td->td_sel = NULL; 393 return (0); 394 } 395 396 /* 397 * Tear down type-stable parts of a thread (just before being discarded). 398 */ 399 static void 400 thread_fini(void *mem, int size) 401 { 402 struct thread *td; 403 404 td = (struct thread *)mem; 405 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td); 406 rlqentry_free(td->td_rlqe); 407 turnstile_free(td->td_turnstile); 408 sleepq_free(td->td_sleepqueue); 409 umtx_thread_fini(td); 410 MPASS(td->td_sel == NULL); 411 } 412 413 /* 414 * For a newly created process, 415 * link up all the structures and its initial threads etc. 416 * called from: 417 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 418 * proc_dtor() (should go away) 419 * proc_init() 420 */ 421 void 422 proc_linkup0(struct proc *p, struct thread *td) 423 { 424 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 425 proc_linkup(p, td); 426 } 427 428 void 429 proc_linkup(struct proc *p, struct thread *td) 430 { 431 432 sigqueue_init(&p->p_sigqueue, p); 433 p->p_ksi = ksiginfo_alloc(1); 434 if (p->p_ksi != NULL) { 435 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 436 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 437 } 438 LIST_INIT(&p->p_mqnotifier); 439 p->p_numthreads = 0; 440 thread_link(td, p); 441 } 442 443 extern int max_threads_per_proc; 444 445 /* 446 * Initialize global thread allocation resources. 447 */ 448 void 449 threadinit(void) 450 { 451 u_long i; 452 lwpid_t tid0; 453 uint32_t flags; 454 455 /* 456 * Place an upper limit on threads which can be allocated. 457 * 458 * Note that other factors may make the de facto limit much lower. 459 * 460 * Platform limits are somewhat arbitrary but deemed "more than good 461 * enough" for the foreseable future. 462 */ 463 if (maxthread == 0) { 464 #ifdef _LP64 465 maxthread = MIN(maxproc * max_threads_per_proc, 1000000); 466 #else 467 maxthread = MIN(maxproc * max_threads_per_proc, 100000); 468 #endif 469 } 470 471 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 472 tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK); 473 /* 474 * Handle thread0. 475 */ 476 thread_count_inc(); 477 tid0 = tid_alloc(); 478 if (tid0 != THREAD0_TID) 479 panic("tid0 %d != %d\n", tid0, THREAD0_TID); 480 481 flags = UMA_ZONE_NOFREE; 482 #ifdef __aarch64__ 483 /* 484 * Force thread structures to be allocated from the direct map. 485 * Otherwise, superpage promotions and demotions may temporarily 486 * invalidate thread structure mappings. For most dynamically allocated 487 * structures this is not a problem, but translation faults cannot be 488 * handled without accessing curthread. 489 */ 490 flags |= UMA_ZONE_CONTIG; 491 #endif 492 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 493 thread_ctor, thread_dtor, thread_init, thread_fini, 494 32 - 1, flags); 495 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 496 tidhashlock = (tidhash + 1) / 64; 497 if (tidhashlock > 0) 498 tidhashlock--; 499 tidhashtbl_lock = malloc(sizeof(*tidhashtbl_lock) * (tidhashlock + 1), 500 M_TIDHASH, M_WAITOK | M_ZERO); 501 for (i = 0; i < tidhashlock + 1; i++) 502 rw_init(&tidhashtbl_lock[i], "tidhash"); 503 } 504 505 /* 506 * Place an unused thread on the zombie list. 507 */ 508 void 509 thread_zombie(struct thread *td) 510 { 511 struct thread *ztd; 512 513 ztd = atomic_load_ptr(&thread_zombies); 514 for (;;) { 515 td->td_zombie = ztd; 516 if (atomic_fcmpset_rel_ptr((uintptr_t *)&thread_zombies, 517 (uintptr_t *)&ztd, (uintptr_t)td)) 518 break; 519 continue; 520 } 521 } 522 523 /* 524 * Release a thread that has exited after cpu_throw(). 525 */ 526 void 527 thread_stash(struct thread *td) 528 { 529 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 530 thread_zombie(td); 531 } 532 533 /* 534 * Reap zombie threads. 535 */ 536 void 537 thread_reap(void) 538 { 539 struct thread *itd, *ntd; 540 struct tidbatch tidbatch; 541 struct credbatch credbatch; 542 int tdcount; 543 struct plimit *lim; 544 int limcount; 545 546 /* 547 * Reading upfront is pessimal if followed by concurrent atomic_swap, 548 * but most of the time the list is empty. 549 */ 550 if (thread_zombies == NULL) 551 return; 552 553 itd = (struct thread *)atomic_swap_ptr((uintptr_t *)&thread_zombies, 554 (uintptr_t)NULL); 555 if (itd == NULL) 556 return; 557 558 tidbatch_prep(&tidbatch); 559 credbatch_prep(&credbatch); 560 tdcount = 0; 561 lim = NULL; 562 limcount = 0; 563 while (itd != NULL) { 564 ntd = itd->td_zombie; 565 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, itd); 566 tidbatch_add(&tidbatch, itd); 567 credbatch_add(&credbatch, itd); 568 MPASS(itd->td_limit != NULL); 569 if (lim != itd->td_limit) { 570 if (limcount != 0) { 571 lim_freen(lim, limcount); 572 limcount = 0; 573 } 574 } 575 lim = itd->td_limit; 576 limcount++; 577 thread_free_batched(itd); 578 tidbatch_process(&tidbatch); 579 credbatch_process(&credbatch); 580 tdcount++; 581 if (tdcount == 32) { 582 thread_count_sub(tdcount); 583 tdcount = 0; 584 } 585 itd = ntd; 586 } 587 588 tidbatch_final(&tidbatch); 589 credbatch_final(&credbatch); 590 if (tdcount != 0) { 591 thread_count_sub(tdcount); 592 } 593 MPASS(limcount != 0); 594 lim_freen(lim, limcount); 595 } 596 597 /* 598 * Allocate a thread. 599 */ 600 struct thread * 601 thread_alloc(int pages) 602 { 603 struct thread *td; 604 lwpid_t tid; 605 606 if (!thread_count_inc()) { 607 return (NULL); 608 } 609 610 tid = tid_alloc(); 611 td = uma_zalloc(thread_zone, M_WAITOK); 612 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 613 if (!vm_thread_new(td, pages)) { 614 uma_zfree(thread_zone, td); 615 tid_free(tid); 616 thread_count_dec(); 617 return (NULL); 618 } 619 td->td_tid = tid; 620 cpu_thread_alloc(td); 621 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); 622 return (td); 623 } 624 625 int 626 thread_alloc_stack(struct thread *td, int pages) 627 { 628 629 KASSERT(td->td_kstack == 0, 630 ("thread_alloc_stack called on a thread with kstack")); 631 if (!vm_thread_new(td, pages)) 632 return (0); 633 cpu_thread_alloc(td); 634 return (1); 635 } 636 637 /* 638 * Deallocate a thread. 639 */ 640 static void 641 thread_free_batched(struct thread *td) 642 { 643 644 lock_profile_thread_exit(td); 645 if (td->td_cpuset) 646 cpuset_rel(td->td_cpuset); 647 td->td_cpuset = NULL; 648 cpu_thread_free(td); 649 if (td->td_kstack != 0) 650 vm_thread_dispose(td); 651 callout_drain(&td->td_slpcallout); 652 /* 653 * Freeing handled by the caller. 654 */ 655 td->td_tid = -1; 656 uma_zfree(thread_zone, td); 657 } 658 659 void 660 thread_free(struct thread *td) 661 { 662 lwpid_t tid; 663 664 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td); 665 tid = td->td_tid; 666 thread_free_batched(td); 667 tid_free(tid); 668 thread_count_dec(); 669 } 670 671 void 672 thread_cow_get_proc(struct thread *newtd, struct proc *p) 673 { 674 675 PROC_LOCK_ASSERT(p, MA_OWNED); 676 newtd->td_realucred = crcowget(p->p_ucred); 677 newtd->td_ucred = newtd->td_realucred; 678 newtd->td_limit = lim_hold(p->p_limit); 679 newtd->td_cowgen = p->p_cowgen; 680 } 681 682 void 683 thread_cow_get(struct thread *newtd, struct thread *td) 684 { 685 686 MPASS(td->td_realucred == td->td_ucred); 687 newtd->td_realucred = crcowget(td->td_realucred); 688 newtd->td_ucred = newtd->td_realucred; 689 newtd->td_limit = lim_hold(td->td_limit); 690 newtd->td_cowgen = td->td_cowgen; 691 } 692 693 void 694 thread_cow_free(struct thread *td) 695 { 696 697 if (td->td_realucred != NULL) 698 crcowfree(td); 699 if (td->td_limit != NULL) 700 lim_free(td->td_limit); 701 } 702 703 void 704 thread_cow_update(struct thread *td) 705 { 706 struct proc *p; 707 struct ucred *oldcred; 708 struct plimit *oldlimit; 709 710 p = td->td_proc; 711 oldlimit = NULL; 712 PROC_LOCK(p); 713 oldcred = crcowsync(); 714 if (td->td_limit != p->p_limit) { 715 oldlimit = td->td_limit; 716 td->td_limit = lim_hold(p->p_limit); 717 } 718 td->td_cowgen = p->p_cowgen; 719 PROC_UNLOCK(p); 720 if (oldcred != NULL) 721 crfree(oldcred); 722 if (oldlimit != NULL) 723 lim_free(oldlimit); 724 } 725 726 /* 727 * Discard the current thread and exit from its context. 728 * Always called with scheduler locked. 729 * 730 * Because we can't free a thread while we're operating under its context, 731 * push the current thread into our CPU's deadthread holder. This means 732 * we needn't worry about someone else grabbing our context before we 733 * do a cpu_throw(). 734 */ 735 void 736 thread_exit(void) 737 { 738 uint64_t runtime, new_switchtime; 739 struct thread *td; 740 struct thread *td2; 741 struct proc *p; 742 int wakeup_swapper; 743 744 td = curthread; 745 p = td->td_proc; 746 747 PROC_SLOCK_ASSERT(p, MA_OWNED); 748 mtx_assert(&Giant, MA_NOTOWNED); 749 750 PROC_LOCK_ASSERT(p, MA_OWNED); 751 KASSERT(p != NULL, ("thread exiting without a process")); 752 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 753 (long)p->p_pid, td->td_name); 754 SDT_PROBE0(proc, , , lwp__exit); 755 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 756 MPASS(td->td_realucred == td->td_ucred); 757 758 /* 759 * drop FPU & debug register state storage, or any other 760 * architecture specific resources that 761 * would not be on a new untouched process. 762 */ 763 cpu_thread_exit(td); 764 765 /* 766 * The last thread is left attached to the process 767 * So that the whole bundle gets recycled. Skip 768 * all this stuff if we never had threads. 769 * EXIT clears all sign of other threads when 770 * it goes to single threading, so the last thread always 771 * takes the short path. 772 */ 773 if (p->p_flag & P_HADTHREADS) { 774 if (p->p_numthreads > 1) { 775 atomic_add_int(&td->td_proc->p_exitthreads, 1); 776 thread_unlink(td); 777 td2 = FIRST_THREAD_IN_PROC(p); 778 sched_exit_thread(td2, td); 779 780 /* 781 * The test below is NOT true if we are the 782 * sole exiting thread. P_STOPPED_SINGLE is unset 783 * in exit1() after it is the only survivor. 784 */ 785 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 786 if (p->p_numthreads == p->p_suspcount) { 787 thread_lock(p->p_singlethread); 788 wakeup_swapper = thread_unsuspend_one( 789 p->p_singlethread, p, false); 790 if (wakeup_swapper) 791 kick_proc0(); 792 } 793 } 794 795 PCPU_SET(deadthread, td); 796 } else { 797 /* 798 * The last thread is exiting.. but not through exit() 799 */ 800 panic ("thread_exit: Last thread exiting on its own"); 801 } 802 } 803 #ifdef HWPMC_HOOKS 804 /* 805 * If this thread is part of a process that is being tracked by hwpmc(4), 806 * inform the module of the thread's impending exit. 807 */ 808 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) { 809 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 810 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL); 811 } else if (PMC_SYSTEM_SAMPLING_ACTIVE()) 812 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL); 813 #endif 814 PROC_UNLOCK(p); 815 PROC_STATLOCK(p); 816 thread_lock(td); 817 PROC_SUNLOCK(p); 818 819 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 820 new_switchtime = cpu_ticks(); 821 runtime = new_switchtime - PCPU_GET(switchtime); 822 td->td_runtime += runtime; 823 td->td_incruntime += runtime; 824 PCPU_SET(switchtime, new_switchtime); 825 PCPU_SET(switchticks, ticks); 826 VM_CNT_INC(v_swtch); 827 828 /* Save our resource usage in our process. */ 829 td->td_ru.ru_nvcsw++; 830 ruxagg_locked(p, td); 831 rucollect(&p->p_ru, &td->td_ru); 832 PROC_STATUNLOCK(p); 833 834 td->td_state = TDS_INACTIVE; 835 #ifdef WITNESS 836 witness_thread_exit(td); 837 #endif 838 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 839 sched_throw(td); 840 panic("I'm a teapot!"); 841 /* NOTREACHED */ 842 } 843 844 /* 845 * Do any thread specific cleanups that may be needed in wait() 846 * called with Giant, proc and schedlock not held. 847 */ 848 void 849 thread_wait(struct proc *p) 850 { 851 struct thread *td; 852 853 mtx_assert(&Giant, MA_NOTOWNED); 854 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 855 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 856 td = FIRST_THREAD_IN_PROC(p); 857 /* Lock the last thread so we spin until it exits cpu_throw(). */ 858 thread_lock(td); 859 thread_unlock(td); 860 lock_profile_thread_exit(td); 861 cpuset_rel(td->td_cpuset); 862 td->td_cpuset = NULL; 863 cpu_thread_clean(td); 864 thread_cow_free(td); 865 callout_drain(&td->td_slpcallout); 866 thread_reap(); /* check for zombie threads etc. */ 867 } 868 869 /* 870 * Link a thread to a process. 871 * set up anything that needs to be initialized for it to 872 * be used by the process. 873 */ 874 void 875 thread_link(struct thread *td, struct proc *p) 876 { 877 878 /* 879 * XXX This can't be enabled because it's called for proc0 before 880 * its lock has been created. 881 * PROC_LOCK_ASSERT(p, MA_OWNED); 882 */ 883 td->td_state = TDS_INACTIVE; 884 td->td_proc = p; 885 td->td_flags = TDF_INMEM; 886 887 LIST_INIT(&td->td_contested); 888 LIST_INIT(&td->td_lprof[0]); 889 LIST_INIT(&td->td_lprof[1]); 890 #ifdef EPOCH_TRACE 891 SLIST_INIT(&td->td_epochs); 892 #endif 893 sigqueue_init(&td->td_sigqueue, p); 894 callout_init(&td->td_slpcallout, 1); 895 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 896 p->p_numthreads++; 897 } 898 899 /* 900 * Called from: 901 * thread_exit() 902 */ 903 void 904 thread_unlink(struct thread *td) 905 { 906 struct proc *p = td->td_proc; 907 908 PROC_LOCK_ASSERT(p, MA_OWNED); 909 #ifdef EPOCH_TRACE 910 MPASS(SLIST_EMPTY(&td->td_epochs)); 911 #endif 912 913 TAILQ_REMOVE(&p->p_threads, td, td_plist); 914 p->p_numthreads--; 915 /* could clear a few other things here */ 916 /* Must NOT clear links to proc! */ 917 } 918 919 static int 920 calc_remaining(struct proc *p, int mode) 921 { 922 int remaining; 923 924 PROC_LOCK_ASSERT(p, MA_OWNED); 925 PROC_SLOCK_ASSERT(p, MA_OWNED); 926 if (mode == SINGLE_EXIT) 927 remaining = p->p_numthreads; 928 else if (mode == SINGLE_BOUNDARY) 929 remaining = p->p_numthreads - p->p_boundary_count; 930 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 931 remaining = p->p_numthreads - p->p_suspcount; 932 else 933 panic("calc_remaining: wrong mode %d", mode); 934 return (remaining); 935 } 936 937 static int 938 remain_for_mode(int mode) 939 { 940 941 return (mode == SINGLE_ALLPROC ? 0 : 1); 942 } 943 944 static int 945 weed_inhib(int mode, struct thread *td2, struct proc *p) 946 { 947 int wakeup_swapper; 948 949 PROC_LOCK_ASSERT(p, MA_OWNED); 950 PROC_SLOCK_ASSERT(p, MA_OWNED); 951 THREAD_LOCK_ASSERT(td2, MA_OWNED); 952 953 wakeup_swapper = 0; 954 955 /* 956 * Since the thread lock is dropped by the scheduler we have 957 * to retry to check for races. 958 */ 959 restart: 960 switch (mode) { 961 case SINGLE_EXIT: 962 if (TD_IS_SUSPENDED(td2)) { 963 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 964 thread_lock(td2); 965 goto restart; 966 } 967 if (TD_CAN_ABORT(td2)) { 968 wakeup_swapper |= sleepq_abort(td2, EINTR); 969 return (wakeup_swapper); 970 } 971 break; 972 case SINGLE_BOUNDARY: 973 case SINGLE_NO_EXIT: 974 if (TD_IS_SUSPENDED(td2) && 975 (td2->td_flags & TDF_BOUNDARY) == 0) { 976 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 977 thread_lock(td2); 978 goto restart; 979 } 980 if (TD_CAN_ABORT(td2)) { 981 wakeup_swapper |= sleepq_abort(td2, ERESTART); 982 return (wakeup_swapper); 983 } 984 break; 985 case SINGLE_ALLPROC: 986 /* 987 * ALLPROC suspend tries to avoid spurious EINTR for 988 * threads sleeping interruptable, by suspending the 989 * thread directly, similarly to sig_suspend_threads(). 990 * Since such sleep is not performed at the user 991 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 992 * is used to avoid immediate un-suspend. 993 */ 994 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 995 TDF_ALLPROCSUSP)) == 0) { 996 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 997 thread_lock(td2); 998 goto restart; 999 } 1000 if (TD_CAN_ABORT(td2)) { 1001 if ((td2->td_flags & TDF_SBDRY) == 0) { 1002 thread_suspend_one(td2); 1003 td2->td_flags |= TDF_ALLPROCSUSP; 1004 } else { 1005 wakeup_swapper |= sleepq_abort(td2, ERESTART); 1006 return (wakeup_swapper); 1007 } 1008 } 1009 break; 1010 default: 1011 break; 1012 } 1013 thread_unlock(td2); 1014 return (wakeup_swapper); 1015 } 1016 1017 /* 1018 * Enforce single-threading. 1019 * 1020 * Returns 1 if the caller must abort (another thread is waiting to 1021 * exit the process or similar). Process is locked! 1022 * Returns 0 when you are successfully the only thread running. 1023 * A process has successfully single threaded in the suspend mode when 1024 * There are no threads in user mode. Threads in the kernel must be 1025 * allowed to continue until they get to the user boundary. They may even 1026 * copy out their return values and data before suspending. They may however be 1027 * accelerated in reaching the user boundary as we will wake up 1028 * any sleeping threads that are interruptable. (PCATCH). 1029 */ 1030 int 1031 thread_single(struct proc *p, int mode) 1032 { 1033 struct thread *td; 1034 struct thread *td2; 1035 int remaining, wakeup_swapper; 1036 1037 td = curthread; 1038 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1039 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1040 ("invalid mode %d", mode)); 1041 /* 1042 * If allowing non-ALLPROC singlethreading for non-curproc 1043 * callers, calc_remaining() and remain_for_mode() should be 1044 * adjusted to also account for td->td_proc != p. For now 1045 * this is not implemented because it is not used. 1046 */ 1047 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 1048 (mode != SINGLE_ALLPROC && td->td_proc == p), 1049 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 1050 mtx_assert(&Giant, MA_NOTOWNED); 1051 PROC_LOCK_ASSERT(p, MA_OWNED); 1052 1053 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 1054 return (0); 1055 1056 /* Is someone already single threading? */ 1057 if (p->p_singlethread != NULL && p->p_singlethread != td) 1058 return (1); 1059 1060 if (mode == SINGLE_EXIT) { 1061 p->p_flag |= P_SINGLE_EXIT; 1062 p->p_flag &= ~P_SINGLE_BOUNDARY; 1063 } else { 1064 p->p_flag &= ~P_SINGLE_EXIT; 1065 if (mode == SINGLE_BOUNDARY) 1066 p->p_flag |= P_SINGLE_BOUNDARY; 1067 else 1068 p->p_flag &= ~P_SINGLE_BOUNDARY; 1069 } 1070 if (mode == SINGLE_ALLPROC) 1071 p->p_flag |= P_TOTAL_STOP; 1072 p->p_flag |= P_STOPPED_SINGLE; 1073 PROC_SLOCK(p); 1074 p->p_singlethread = td; 1075 remaining = calc_remaining(p, mode); 1076 while (remaining != remain_for_mode(mode)) { 1077 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 1078 goto stopme; 1079 wakeup_swapper = 0; 1080 FOREACH_THREAD_IN_PROC(p, td2) { 1081 if (td2 == td) 1082 continue; 1083 thread_lock(td2); 1084 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 1085 if (TD_IS_INHIBITED(td2)) { 1086 wakeup_swapper |= weed_inhib(mode, td2, p); 1087 #ifdef SMP 1088 } else if (TD_IS_RUNNING(td2) && td != td2) { 1089 forward_signal(td2); 1090 thread_unlock(td2); 1091 #endif 1092 } else 1093 thread_unlock(td2); 1094 } 1095 if (wakeup_swapper) 1096 kick_proc0(); 1097 remaining = calc_remaining(p, mode); 1098 1099 /* 1100 * Maybe we suspended some threads.. was it enough? 1101 */ 1102 if (remaining == remain_for_mode(mode)) 1103 break; 1104 1105 stopme: 1106 /* 1107 * Wake us up when everyone else has suspended. 1108 * In the mean time we suspend as well. 1109 */ 1110 thread_suspend_switch(td, p); 1111 remaining = calc_remaining(p, mode); 1112 } 1113 if (mode == SINGLE_EXIT) { 1114 /* 1115 * Convert the process to an unthreaded process. The 1116 * SINGLE_EXIT is called by exit1() or execve(), in 1117 * both cases other threads must be retired. 1118 */ 1119 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 1120 p->p_singlethread = NULL; 1121 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 1122 1123 /* 1124 * Wait for any remaining threads to exit cpu_throw(). 1125 */ 1126 while (p->p_exitthreads != 0) { 1127 PROC_SUNLOCK(p); 1128 PROC_UNLOCK(p); 1129 sched_relinquish(td); 1130 PROC_LOCK(p); 1131 PROC_SLOCK(p); 1132 } 1133 } else if (mode == SINGLE_BOUNDARY) { 1134 /* 1135 * Wait until all suspended threads are removed from 1136 * the processors. The thread_suspend_check() 1137 * increments p_boundary_count while it is still 1138 * running, which makes it possible for the execve() 1139 * to destroy vmspace while our other threads are 1140 * still using the address space. 1141 * 1142 * We lock the thread, which is only allowed to 1143 * succeed after context switch code finished using 1144 * the address space. 1145 */ 1146 FOREACH_THREAD_IN_PROC(p, td2) { 1147 if (td2 == td) 1148 continue; 1149 thread_lock(td2); 1150 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 1151 ("td %p not on boundary", td2)); 1152 KASSERT(TD_IS_SUSPENDED(td2), 1153 ("td %p is not suspended", td2)); 1154 thread_unlock(td2); 1155 } 1156 } 1157 PROC_SUNLOCK(p); 1158 return (0); 1159 } 1160 1161 bool 1162 thread_suspend_check_needed(void) 1163 { 1164 struct proc *p; 1165 struct thread *td; 1166 1167 td = curthread; 1168 p = td->td_proc; 1169 PROC_LOCK_ASSERT(p, MA_OWNED); 1170 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 1171 (td->td_dbgflags & TDB_SUSPEND) != 0)); 1172 } 1173 1174 /* 1175 * Called in from locations that can safely check to see 1176 * whether we have to suspend or at least throttle for a 1177 * single-thread event (e.g. fork). 1178 * 1179 * Such locations include userret(). 1180 * If the "return_instead" argument is non zero, the thread must be able to 1181 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 1182 * 1183 * The 'return_instead' argument tells the function if it may do a 1184 * thread_exit() or suspend, or whether the caller must abort and back 1185 * out instead. 1186 * 1187 * If the thread that set the single_threading request has set the 1188 * P_SINGLE_EXIT bit in the process flags then this call will never return 1189 * if 'return_instead' is false, but will exit. 1190 * 1191 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 1192 *---------------+--------------------+--------------------- 1193 * 0 | returns 0 | returns 0 or 1 1194 * | when ST ends | immediately 1195 *---------------+--------------------+--------------------- 1196 * 1 | thread exits | returns 1 1197 * | | immediately 1198 * 0 = thread_exit() or suspension ok, 1199 * other = return error instead of stopping the thread. 1200 * 1201 * While a full suspension is under effect, even a single threading 1202 * thread would be suspended if it made this call (but it shouldn't). 1203 * This call should only be made from places where 1204 * thread_exit() would be safe as that may be the outcome unless 1205 * return_instead is set. 1206 */ 1207 int 1208 thread_suspend_check(int return_instead) 1209 { 1210 struct thread *td; 1211 struct proc *p; 1212 int wakeup_swapper; 1213 1214 td = curthread; 1215 p = td->td_proc; 1216 mtx_assert(&Giant, MA_NOTOWNED); 1217 PROC_LOCK_ASSERT(p, MA_OWNED); 1218 while (thread_suspend_check_needed()) { 1219 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1220 KASSERT(p->p_singlethread != NULL, 1221 ("singlethread not set")); 1222 /* 1223 * The only suspension in action is a 1224 * single-threading. Single threader need not stop. 1225 * It is safe to access p->p_singlethread unlocked 1226 * because it can only be set to our address by us. 1227 */ 1228 if (p->p_singlethread == td) 1229 return (0); /* Exempt from stopping. */ 1230 } 1231 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 1232 return (EINTR); 1233 1234 /* Should we goto user boundary if we didn't come from there? */ 1235 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1236 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 1237 return (ERESTART); 1238 1239 /* 1240 * Ignore suspend requests if they are deferred. 1241 */ 1242 if ((td->td_flags & TDF_SBDRY) != 0) { 1243 KASSERT(return_instead, 1244 ("TDF_SBDRY set for unsafe thread_suspend_check")); 1245 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 1246 (TDF_SEINTR | TDF_SERESTART), 1247 ("both TDF_SEINTR and TDF_SERESTART")); 1248 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 1249 } 1250 1251 /* 1252 * If the process is waiting for us to exit, 1253 * this thread should just suicide. 1254 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 1255 */ 1256 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 1257 PROC_UNLOCK(p); 1258 1259 /* 1260 * Allow Linux emulation layer to do some work 1261 * before thread suicide. 1262 */ 1263 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 1264 (p->p_sysent->sv_thread_detach)(td); 1265 umtx_thread_exit(td); 1266 kern_thr_exit(td); 1267 panic("stopped thread did not exit"); 1268 } 1269 1270 PROC_SLOCK(p); 1271 thread_stopped(p); 1272 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1273 if (p->p_numthreads == p->p_suspcount + 1) { 1274 thread_lock(p->p_singlethread); 1275 wakeup_swapper = thread_unsuspend_one( 1276 p->p_singlethread, p, false); 1277 if (wakeup_swapper) 1278 kick_proc0(); 1279 } 1280 } 1281 PROC_UNLOCK(p); 1282 thread_lock(td); 1283 /* 1284 * When a thread suspends, it just 1285 * gets taken off all queues. 1286 */ 1287 thread_suspend_one(td); 1288 if (return_instead == 0) { 1289 p->p_boundary_count++; 1290 td->td_flags |= TDF_BOUNDARY; 1291 } 1292 PROC_SUNLOCK(p); 1293 mi_switch(SW_INVOL | SWT_SUSPEND); 1294 PROC_LOCK(p); 1295 } 1296 return (0); 1297 } 1298 1299 /* 1300 * Check for possible stops and suspensions while executing a 1301 * casueword or similar transiently failing operation. 1302 * 1303 * The sleep argument controls whether the function can handle a stop 1304 * request itself or it should return ERESTART and the request is 1305 * proceed at the kernel/user boundary in ast. 1306 * 1307 * Typically, when retrying due to casueword(9) failure (rv == 1), we 1308 * should handle the stop requests there, with exception of cases when 1309 * the thread owns a kernel resource, for instance busied the umtx 1310 * key, or when functions return immediately if thread_check_susp() 1311 * returned non-zero. On the other hand, retrying the whole lock 1312 * operation, we better not stop there but delegate the handling to 1313 * ast. 1314 * 1315 * If the request is for thread termination P_SINGLE_EXIT, we cannot 1316 * handle it at all, and simply return EINTR. 1317 */ 1318 int 1319 thread_check_susp(struct thread *td, bool sleep) 1320 { 1321 struct proc *p; 1322 int error; 1323 1324 /* 1325 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to 1326 * eventually break the lockstep loop. 1327 */ 1328 if ((td->td_flags & TDF_NEEDSUSPCHK) == 0) 1329 return (0); 1330 error = 0; 1331 p = td->td_proc; 1332 PROC_LOCK(p); 1333 if (p->p_flag & P_SINGLE_EXIT) 1334 error = EINTR; 1335 else if (P_SHOULDSTOP(p) || 1336 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) 1337 error = sleep ? thread_suspend_check(0) : ERESTART; 1338 PROC_UNLOCK(p); 1339 return (error); 1340 } 1341 1342 void 1343 thread_suspend_switch(struct thread *td, struct proc *p) 1344 { 1345 1346 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1347 PROC_LOCK_ASSERT(p, MA_OWNED); 1348 PROC_SLOCK_ASSERT(p, MA_OWNED); 1349 /* 1350 * We implement thread_suspend_one in stages here to avoid 1351 * dropping the proc lock while the thread lock is owned. 1352 */ 1353 if (p == td->td_proc) { 1354 thread_stopped(p); 1355 p->p_suspcount++; 1356 } 1357 PROC_UNLOCK(p); 1358 thread_lock(td); 1359 td->td_flags &= ~TDF_NEEDSUSPCHK; 1360 TD_SET_SUSPENDED(td); 1361 sched_sleep(td, 0); 1362 PROC_SUNLOCK(p); 1363 DROP_GIANT(); 1364 mi_switch(SW_VOL | SWT_SUSPEND); 1365 PICKUP_GIANT(); 1366 PROC_LOCK(p); 1367 PROC_SLOCK(p); 1368 } 1369 1370 void 1371 thread_suspend_one(struct thread *td) 1372 { 1373 struct proc *p; 1374 1375 p = td->td_proc; 1376 PROC_SLOCK_ASSERT(p, MA_OWNED); 1377 THREAD_LOCK_ASSERT(td, MA_OWNED); 1378 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1379 p->p_suspcount++; 1380 td->td_flags &= ~TDF_NEEDSUSPCHK; 1381 TD_SET_SUSPENDED(td); 1382 sched_sleep(td, 0); 1383 } 1384 1385 static int 1386 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1387 { 1388 1389 THREAD_LOCK_ASSERT(td, MA_OWNED); 1390 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1391 TD_CLR_SUSPENDED(td); 1392 td->td_flags &= ~TDF_ALLPROCSUSP; 1393 if (td->td_proc == p) { 1394 PROC_SLOCK_ASSERT(p, MA_OWNED); 1395 p->p_suspcount--; 1396 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1397 td->td_flags &= ~TDF_BOUNDARY; 1398 p->p_boundary_count--; 1399 } 1400 } 1401 return (setrunnable(td, 0)); 1402 } 1403 1404 /* 1405 * Allow all threads blocked by single threading to continue running. 1406 */ 1407 void 1408 thread_unsuspend(struct proc *p) 1409 { 1410 struct thread *td; 1411 int wakeup_swapper; 1412 1413 PROC_LOCK_ASSERT(p, MA_OWNED); 1414 PROC_SLOCK_ASSERT(p, MA_OWNED); 1415 wakeup_swapper = 0; 1416 if (!P_SHOULDSTOP(p)) { 1417 FOREACH_THREAD_IN_PROC(p, td) { 1418 thread_lock(td); 1419 if (TD_IS_SUSPENDED(td)) { 1420 wakeup_swapper |= thread_unsuspend_one(td, p, 1421 true); 1422 } else 1423 thread_unlock(td); 1424 } 1425 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1426 p->p_numthreads == p->p_suspcount) { 1427 /* 1428 * Stopping everything also did the job for the single 1429 * threading request. Now we've downgraded to single-threaded, 1430 * let it continue. 1431 */ 1432 if (p->p_singlethread->td_proc == p) { 1433 thread_lock(p->p_singlethread); 1434 wakeup_swapper = thread_unsuspend_one( 1435 p->p_singlethread, p, false); 1436 } 1437 } 1438 if (wakeup_swapper) 1439 kick_proc0(); 1440 } 1441 1442 /* 1443 * End the single threading mode.. 1444 */ 1445 void 1446 thread_single_end(struct proc *p, int mode) 1447 { 1448 struct thread *td; 1449 int wakeup_swapper; 1450 1451 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1452 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1453 ("invalid mode %d", mode)); 1454 PROC_LOCK_ASSERT(p, MA_OWNED); 1455 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1456 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1457 ("mode %d does not match P_TOTAL_STOP", mode)); 1458 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1459 ("thread_single_end from other thread %p %p", 1460 curthread, p->p_singlethread)); 1461 KASSERT(mode != SINGLE_BOUNDARY || 1462 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1463 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1464 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1465 P_TOTAL_STOP); 1466 PROC_SLOCK(p); 1467 p->p_singlethread = NULL; 1468 wakeup_swapper = 0; 1469 /* 1470 * If there are other threads they may now run, 1471 * unless of course there is a blanket 'stop order' 1472 * on the process. The single threader must be allowed 1473 * to continue however as this is a bad place to stop. 1474 */ 1475 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1476 FOREACH_THREAD_IN_PROC(p, td) { 1477 thread_lock(td); 1478 if (TD_IS_SUSPENDED(td)) { 1479 wakeup_swapper |= thread_unsuspend_one(td, p, 1480 mode == SINGLE_BOUNDARY); 1481 } else 1482 thread_unlock(td); 1483 } 1484 } 1485 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1486 ("inconsistent boundary count %d", p->p_boundary_count)); 1487 PROC_SUNLOCK(p); 1488 if (wakeup_swapper) 1489 kick_proc0(); 1490 } 1491 1492 /* 1493 * Locate a thread by number and return with proc lock held. 1494 * 1495 * thread exit establishes proc -> tidhash lock ordering, but lookup 1496 * takes tidhash first and needs to return locked proc. 1497 * 1498 * The problem is worked around by relying on type-safety of both 1499 * structures and doing the work in 2 steps: 1500 * - tidhash-locked lookup which saves both thread and proc pointers 1501 * - proc-locked verification that the found thread still matches 1502 */ 1503 static bool 1504 tdfind_hash(lwpid_t tid, pid_t pid, struct proc **pp, struct thread **tdp) 1505 { 1506 #define RUN_THRESH 16 1507 struct proc *p; 1508 struct thread *td; 1509 int run; 1510 bool locked; 1511 1512 run = 0; 1513 rw_rlock(TIDHASHLOCK(tid)); 1514 locked = true; 1515 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1516 if (td->td_tid != tid) { 1517 run++; 1518 continue; 1519 } 1520 p = td->td_proc; 1521 if (pid != -1 && p->p_pid != pid) { 1522 td = NULL; 1523 break; 1524 } 1525 if (run > RUN_THRESH) { 1526 if (rw_try_upgrade(TIDHASHLOCK(tid))) { 1527 LIST_REMOVE(td, td_hash); 1528 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1529 td, td_hash); 1530 rw_wunlock(TIDHASHLOCK(tid)); 1531 locked = false; 1532 break; 1533 } 1534 } 1535 break; 1536 } 1537 if (locked) 1538 rw_runlock(TIDHASHLOCK(tid)); 1539 if (td == NULL) 1540 return (false); 1541 *pp = p; 1542 *tdp = td; 1543 return (true); 1544 } 1545 1546 struct thread * 1547 tdfind(lwpid_t tid, pid_t pid) 1548 { 1549 struct proc *p; 1550 struct thread *td; 1551 1552 td = curthread; 1553 if (td->td_tid == tid) { 1554 if (pid != -1 && td->td_proc->p_pid != pid) 1555 return (NULL); 1556 PROC_LOCK(td->td_proc); 1557 return (td); 1558 } 1559 1560 for (;;) { 1561 if (!tdfind_hash(tid, pid, &p, &td)) 1562 return (NULL); 1563 PROC_LOCK(p); 1564 if (td->td_tid != tid) { 1565 PROC_UNLOCK(p); 1566 continue; 1567 } 1568 if (td->td_proc != p) { 1569 PROC_UNLOCK(p); 1570 continue; 1571 } 1572 if (p->p_state == PRS_NEW) { 1573 PROC_UNLOCK(p); 1574 return (NULL); 1575 } 1576 return (td); 1577 } 1578 } 1579 1580 void 1581 tidhash_add(struct thread *td) 1582 { 1583 rw_wlock(TIDHASHLOCK(td->td_tid)); 1584 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1585 rw_wunlock(TIDHASHLOCK(td->td_tid)); 1586 } 1587 1588 void 1589 tidhash_remove(struct thread *td) 1590 { 1591 1592 rw_wlock(TIDHASHLOCK(td->td_tid)); 1593 LIST_REMOVE(td, td_hash); 1594 rw_wunlock(TIDHASHLOCK(td->td_tid)); 1595 } 1596