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) == 0xb0, 92 "struct proc KBI p_flag"); 93 _Static_assert(offsetof(struct proc, p_pid) == 0xbc, 94 "struct proc KBI p_pid"); 95 _Static_assert(offsetof(struct proc, p_filemon) == 0x3b8, 96 "struct proc KBI p_filemon"); 97 _Static_assert(offsetof(struct proc, p_comm) == 0x3d0, 98 "struct proc KBI p_comm"); 99 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4b0, 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) == 0x68, 112 "struct proc KBI p_flag"); 113 _Static_assert(offsetof(struct proc, p_pid) == 0x74, 114 "struct proc KBI p_pid"); 115 _Static_assert(offsetof(struct proc, p_filemon) == 0x268, 116 "struct proc KBI p_filemon"); 117 _Static_assert(offsetof(struct proc, p_comm) == 0x27c, 118 "struct proc KBI p_comm"); 119 _Static_assert(offsetof(struct proc, p_emuldata) == 0x308, 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 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 132 static struct mtx zombie_lock; 133 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 134 135 static void thread_zombie(struct thread *); 136 static int thread_unsuspend_one(struct thread *td, struct proc *p, 137 bool boundary); 138 139 static struct mtx tid_lock; 140 static bitstr_t *tid_bitmap; 141 142 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 143 144 static int maxthread; 145 SYSCTL_INT(_kern, OID_AUTO, maxthread, CTLFLAG_RDTUN, 146 &maxthread, 0, "Maximum number of threads"); 147 148 static int nthreads; 149 150 struct tidhashhead *tidhashtbl; 151 u_long tidhash; 152 struct rwlock tidhash_lock; 153 154 EVENTHANDLER_LIST_DEFINE(thread_ctor); 155 EVENTHANDLER_LIST_DEFINE(thread_dtor); 156 EVENTHANDLER_LIST_DEFINE(thread_init); 157 EVENTHANDLER_LIST_DEFINE(thread_fini); 158 159 static lwpid_t 160 tid_alloc(void) 161 { 162 static struct timeval lastfail; 163 static int curfail; 164 static lwpid_t trytid; 165 lwpid_t tid; 166 167 mtx_lock(&tid_lock); 168 if (nthreads + 1 >= maxthread - 100) { 169 if (priv_check_cred(curthread->td_ucred, PRIV_MAXPROC) != 0 || 170 nthreads + 1 >= maxthread) { 171 mtx_unlock(&tid_lock); 172 if (ppsratecheck(&lastfail, &curfail, 1)) { 173 printf("maxthread limit exceeded by uid %u " 174 "(pid %d); consider increasing kern.maxthread\n", 175 curthread->td_ucred->cr_ruid, curproc->p_pid); 176 } 177 return (-1); 178 } 179 } 180 181 nthreads++; 182 /* 183 * It is an invariant that the bitmap is big enough to hold maxthread 184 * IDs. If we got to this point there has to be at least one free. 185 */ 186 if (trytid >= maxthread) 187 trytid = 0; 188 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 189 if (tid == -1) { 190 KASSERT(trytid != 0, ("unexpectedly ran out of IDs")); 191 trytid = 0; 192 bit_ffc_at(tid_bitmap, trytid, maxthread, &tid); 193 KASSERT(tid != -1, ("unexpectedly ran out of IDs")); 194 } 195 bit_set(tid_bitmap, tid); 196 trytid = tid + 1; 197 mtx_unlock(&tid_lock); 198 return (tid + NO_PID); 199 } 200 201 static void 202 tid_free(lwpid_t rtid) 203 { 204 lwpid_t tid; 205 206 KASSERT(rtid >= NO_PID, 207 ("%s: invalid tid %d\n", __func__, rtid)); 208 tid = rtid - NO_PID; 209 mtx_lock(&tid_lock); 210 KASSERT(bit_test(tid_bitmap, tid) != 0, 211 ("thread ID %d not allocated\n", rtid)); 212 bit_clear(tid_bitmap, tid); 213 nthreads--; 214 mtx_unlock(&tid_lock); 215 } 216 217 /* 218 * Prepare a thread for use. 219 */ 220 static int 221 thread_ctor(void *mem, int size, void *arg, int flags) 222 { 223 struct thread *td; 224 225 td = (struct thread *)mem; 226 td->td_state = TDS_INACTIVE; 227 td->td_lastcpu = td->td_oncpu = NOCPU; 228 229 /* 230 * Note that td_critnest begins life as 1 because the thread is not 231 * running and is thereby implicitly waiting to be on the receiving 232 * end of a context switch. 233 */ 234 td->td_critnest = 1; 235 td->td_lend_user_pri = PRI_MAX; 236 #ifdef AUDIT 237 audit_thread_alloc(td); 238 #endif 239 umtx_thread_alloc(td); 240 return (0); 241 } 242 243 /* 244 * Reclaim a thread after use. 245 */ 246 static void 247 thread_dtor(void *mem, int size, void *arg) 248 { 249 struct thread *td; 250 251 td = (struct thread *)mem; 252 253 #ifdef INVARIANTS 254 /* Verify that this thread is in a safe state to free. */ 255 switch (td->td_state) { 256 case TDS_INHIBITED: 257 case TDS_RUNNING: 258 case TDS_CAN_RUN: 259 case TDS_RUNQ: 260 /* 261 * We must never unlink a thread that is in one of 262 * these states, because it is currently active. 263 */ 264 panic("bad state for thread unlinking"); 265 /* NOTREACHED */ 266 case TDS_INACTIVE: 267 break; 268 default: 269 panic("bad thread state"); 270 /* NOTREACHED */ 271 } 272 #endif 273 #ifdef AUDIT 274 audit_thread_free(td); 275 #endif 276 /* Free all OSD associated to this thread. */ 277 osd_thread_exit(td); 278 td_softdep_cleanup(td); 279 MPASS(td->td_su == NULL); 280 } 281 282 /* 283 * Initialize type-stable parts of a thread (when newly created). 284 */ 285 static int 286 thread_init(void *mem, int size, int flags) 287 { 288 struct thread *td; 289 290 td = (struct thread *)mem; 291 292 td->td_sleepqueue = sleepq_alloc(); 293 td->td_turnstile = turnstile_alloc(); 294 td->td_rlqe = NULL; 295 EVENTHANDLER_DIRECT_INVOKE(thread_init, td); 296 umtx_thread_init(td); 297 td->td_kstack = 0; 298 td->td_sel = NULL; 299 return (0); 300 } 301 302 /* 303 * Tear down type-stable parts of a thread (just before being discarded). 304 */ 305 static void 306 thread_fini(void *mem, int size) 307 { 308 struct thread *td; 309 310 td = (struct thread *)mem; 311 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td); 312 rlqentry_free(td->td_rlqe); 313 turnstile_free(td->td_turnstile); 314 sleepq_free(td->td_sleepqueue); 315 umtx_thread_fini(td); 316 seltdfini(td); 317 } 318 319 /* 320 * For a newly created process, 321 * link up all the structures and its initial threads etc. 322 * called from: 323 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 324 * proc_dtor() (should go away) 325 * proc_init() 326 */ 327 void 328 proc_linkup0(struct proc *p, struct thread *td) 329 { 330 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 331 proc_linkup(p, td); 332 } 333 334 void 335 proc_linkup(struct proc *p, struct thread *td) 336 { 337 338 sigqueue_init(&p->p_sigqueue, p); 339 p->p_ksi = ksiginfo_alloc(1); 340 if (p->p_ksi != NULL) { 341 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 342 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 343 } 344 LIST_INIT(&p->p_mqnotifier); 345 p->p_numthreads = 0; 346 thread_link(td, p); 347 } 348 349 extern int max_threads_per_proc; 350 351 /* 352 * Initialize global thread allocation resources. 353 */ 354 void 355 threadinit(void) 356 { 357 uint32_t flags; 358 359 /* 360 * Place an upper limit on threads which can be allocated. 361 * 362 * Note that other factors may make the de facto limit much lower. 363 * 364 * Platform limits are somewhat arbitrary but deemed "more than good 365 * enough" for the foreseable future. 366 */ 367 if (maxthread == 0) { 368 #ifdef _LP64 369 maxthread = MIN(maxproc * max_threads_per_proc, 1000000); 370 #else 371 maxthread = MIN(maxproc * max_threads_per_proc, 100000); 372 #endif 373 } 374 375 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 376 tid_bitmap = bit_alloc(maxthread, M_TIDHASH, M_WAITOK); 377 378 flags = UMA_ZONE_NOFREE; 379 #ifdef __aarch64__ 380 /* 381 * Force thread structures to be allocated from the direct map. 382 * Otherwise, superpage promotions and demotions may temporarily 383 * invalidate thread structure mappings. For most dynamically allocated 384 * structures this is not a problem, but translation faults cannot be 385 * handled without accessing curthread. 386 */ 387 flags |= UMA_ZONE_CONTIG; 388 #endif 389 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 390 thread_ctor, thread_dtor, thread_init, thread_fini, 391 32 - 1, flags); 392 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 393 rw_init(&tidhash_lock, "tidhash"); 394 } 395 396 /* 397 * Place an unused thread on the zombie list. 398 * Use the slpq as that must be unused by now. 399 */ 400 void 401 thread_zombie(struct thread *td) 402 { 403 mtx_lock_spin(&zombie_lock); 404 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 405 mtx_unlock_spin(&zombie_lock); 406 } 407 408 /* 409 * Release a thread that has exited after cpu_throw(). 410 */ 411 void 412 thread_stash(struct thread *td) 413 { 414 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 415 thread_zombie(td); 416 } 417 418 /* 419 * Reap zombie resources. 420 */ 421 void 422 thread_reap(void) 423 { 424 struct thread *td_first, *td_next; 425 426 /* 427 * Don't even bother to lock if none at this instant, 428 * we really don't care about the next instant. 429 */ 430 if (!TAILQ_EMPTY(&zombie_threads)) { 431 mtx_lock_spin(&zombie_lock); 432 td_first = TAILQ_FIRST(&zombie_threads); 433 if (td_first) 434 TAILQ_INIT(&zombie_threads); 435 mtx_unlock_spin(&zombie_lock); 436 while (td_first) { 437 td_next = TAILQ_NEXT(td_first, td_slpq); 438 thread_cow_free(td_first); 439 thread_free(td_first); 440 td_first = td_next; 441 } 442 } 443 } 444 445 /* 446 * Allocate a thread. 447 */ 448 struct thread * 449 thread_alloc(int pages) 450 { 451 struct thread *td; 452 lwpid_t tid; 453 454 thread_reap(); /* check if any zombies to get */ 455 456 tid = tid_alloc(); 457 if (tid == -1) { 458 return (NULL); 459 } 460 461 td = uma_zalloc(thread_zone, M_WAITOK); 462 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 463 if (!vm_thread_new(td, pages)) { 464 uma_zfree(thread_zone, td); 465 tid_free(tid); 466 return (NULL); 467 } 468 td->td_tid = tid; 469 cpu_thread_alloc(td); 470 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); 471 return (td); 472 } 473 474 int 475 thread_alloc_stack(struct thread *td, int pages) 476 { 477 478 KASSERT(td->td_kstack == 0, 479 ("thread_alloc_stack called on a thread with kstack")); 480 if (!vm_thread_new(td, pages)) 481 return (0); 482 cpu_thread_alloc(td); 483 return (1); 484 } 485 486 /* 487 * Deallocate a thread. 488 */ 489 void 490 thread_free(struct thread *td) 491 { 492 493 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td); 494 lock_profile_thread_exit(td); 495 if (td->td_cpuset) 496 cpuset_rel(td->td_cpuset); 497 td->td_cpuset = NULL; 498 cpu_thread_free(td); 499 if (td->td_kstack != 0) 500 vm_thread_dispose(td); 501 callout_drain(&td->td_slpcallout); 502 tid_free(td->td_tid); 503 td->td_tid = -1; 504 uma_zfree(thread_zone, td); 505 } 506 507 void 508 thread_cow_get_proc(struct thread *newtd, struct proc *p) 509 { 510 511 PROC_LOCK_ASSERT(p, MA_OWNED); 512 newtd->td_realucred = crcowget(p->p_ucred); 513 newtd->td_ucred = newtd->td_realucred; 514 newtd->td_limit = lim_hold(p->p_limit); 515 newtd->td_cowgen = p->p_cowgen; 516 } 517 518 void 519 thread_cow_get(struct thread *newtd, struct thread *td) 520 { 521 522 MPASS(td->td_realucred == td->td_ucred); 523 newtd->td_realucred = crcowget(td->td_realucred); 524 newtd->td_ucred = newtd->td_realucred; 525 newtd->td_limit = lim_hold(td->td_limit); 526 newtd->td_cowgen = td->td_cowgen; 527 } 528 529 void 530 thread_cow_free(struct thread *td) 531 { 532 533 if (td->td_realucred != NULL) 534 crcowfree(td); 535 if (td->td_limit != NULL) 536 lim_free(td->td_limit); 537 } 538 539 void 540 thread_cow_update(struct thread *td) 541 { 542 struct proc *p; 543 struct ucred *oldcred; 544 struct plimit *oldlimit; 545 546 p = td->td_proc; 547 oldlimit = NULL; 548 PROC_LOCK(p); 549 oldcred = crcowsync(); 550 if (td->td_limit != p->p_limit) { 551 oldlimit = td->td_limit; 552 td->td_limit = lim_hold(p->p_limit); 553 } 554 td->td_cowgen = p->p_cowgen; 555 PROC_UNLOCK(p); 556 if (oldcred != NULL) 557 crfree(oldcred); 558 if (oldlimit != NULL) 559 lim_free(oldlimit); 560 } 561 562 /* 563 * Discard the current thread and exit from its context. 564 * Always called with scheduler locked. 565 * 566 * Because we can't free a thread while we're operating under its context, 567 * push the current thread into our CPU's deadthread holder. This means 568 * we needn't worry about someone else grabbing our context before we 569 * do a cpu_throw(). 570 */ 571 void 572 thread_exit(void) 573 { 574 uint64_t runtime, new_switchtime; 575 struct thread *td; 576 struct thread *td2; 577 struct proc *p; 578 int wakeup_swapper; 579 580 td = curthread; 581 p = td->td_proc; 582 583 PROC_SLOCK_ASSERT(p, MA_OWNED); 584 mtx_assert(&Giant, MA_NOTOWNED); 585 586 PROC_LOCK_ASSERT(p, MA_OWNED); 587 KASSERT(p != NULL, ("thread exiting without a process")); 588 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 589 (long)p->p_pid, td->td_name); 590 SDT_PROBE0(proc, , , lwp__exit); 591 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 592 MPASS(td->td_realucred == td->td_ucred); 593 594 /* 595 * drop FPU & debug register state storage, or any other 596 * architecture specific resources that 597 * would not be on a new untouched process. 598 */ 599 cpu_thread_exit(td); 600 601 /* 602 * The last thread is left attached to the process 603 * So that the whole bundle gets recycled. Skip 604 * all this stuff if we never had threads. 605 * EXIT clears all sign of other threads when 606 * it goes to single threading, so the last thread always 607 * takes the short path. 608 */ 609 if (p->p_flag & P_HADTHREADS) { 610 if (p->p_numthreads > 1) { 611 atomic_add_int(&td->td_proc->p_exitthreads, 1); 612 thread_unlink(td); 613 td2 = FIRST_THREAD_IN_PROC(p); 614 sched_exit_thread(td2, td); 615 616 /* 617 * The test below is NOT true if we are the 618 * sole exiting thread. P_STOPPED_SINGLE is unset 619 * in exit1() after it is the only survivor. 620 */ 621 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 622 if (p->p_numthreads == p->p_suspcount) { 623 thread_lock(p->p_singlethread); 624 wakeup_swapper = thread_unsuspend_one( 625 p->p_singlethread, p, false); 626 if (wakeup_swapper) 627 kick_proc0(); 628 } 629 } 630 631 PCPU_SET(deadthread, td); 632 } else { 633 /* 634 * The last thread is exiting.. but not through exit() 635 */ 636 panic ("thread_exit: Last thread exiting on its own"); 637 } 638 } 639 #ifdef HWPMC_HOOKS 640 /* 641 * If this thread is part of a process that is being tracked by hwpmc(4), 642 * inform the module of the thread's impending exit. 643 */ 644 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) { 645 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 646 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL); 647 } else if (PMC_SYSTEM_SAMPLING_ACTIVE()) 648 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL); 649 #endif 650 PROC_UNLOCK(p); 651 PROC_STATLOCK(p); 652 thread_lock(td); 653 PROC_SUNLOCK(p); 654 655 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 656 new_switchtime = cpu_ticks(); 657 runtime = new_switchtime - PCPU_GET(switchtime); 658 td->td_runtime += runtime; 659 td->td_incruntime += runtime; 660 PCPU_SET(switchtime, new_switchtime); 661 PCPU_SET(switchticks, ticks); 662 VM_CNT_INC(v_swtch); 663 664 /* Save our resource usage in our process. */ 665 td->td_ru.ru_nvcsw++; 666 ruxagg_locked(p, td); 667 rucollect(&p->p_ru, &td->td_ru); 668 PROC_STATUNLOCK(p); 669 670 td->td_state = TDS_INACTIVE; 671 #ifdef WITNESS 672 witness_thread_exit(td); 673 #endif 674 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 675 sched_throw(td); 676 panic("I'm a teapot!"); 677 /* NOTREACHED */ 678 } 679 680 /* 681 * Do any thread specific cleanups that may be needed in wait() 682 * called with Giant, proc and schedlock not held. 683 */ 684 void 685 thread_wait(struct proc *p) 686 { 687 struct thread *td; 688 689 mtx_assert(&Giant, MA_NOTOWNED); 690 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 691 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 692 td = FIRST_THREAD_IN_PROC(p); 693 /* Lock the last thread so we spin until it exits cpu_throw(). */ 694 thread_lock(td); 695 thread_unlock(td); 696 lock_profile_thread_exit(td); 697 cpuset_rel(td->td_cpuset); 698 td->td_cpuset = NULL; 699 cpu_thread_clean(td); 700 thread_cow_free(td); 701 callout_drain(&td->td_slpcallout); 702 thread_reap(); /* check for zombie threads etc. */ 703 } 704 705 /* 706 * Link a thread to a process. 707 * set up anything that needs to be initialized for it to 708 * be used by the process. 709 */ 710 void 711 thread_link(struct thread *td, struct proc *p) 712 { 713 714 /* 715 * XXX This can't be enabled because it's called for proc0 before 716 * its lock has been created. 717 * PROC_LOCK_ASSERT(p, MA_OWNED); 718 */ 719 td->td_state = TDS_INACTIVE; 720 td->td_proc = p; 721 td->td_flags = TDF_INMEM; 722 723 LIST_INIT(&td->td_contested); 724 LIST_INIT(&td->td_lprof[0]); 725 LIST_INIT(&td->td_lprof[1]); 726 #ifdef EPOCH_TRACE 727 SLIST_INIT(&td->td_epochs); 728 #endif 729 sigqueue_init(&td->td_sigqueue, p); 730 callout_init(&td->td_slpcallout, 1); 731 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 732 p->p_numthreads++; 733 } 734 735 /* 736 * Called from: 737 * thread_exit() 738 */ 739 void 740 thread_unlink(struct thread *td) 741 { 742 struct proc *p = td->td_proc; 743 744 PROC_LOCK_ASSERT(p, MA_OWNED); 745 #ifdef EPOCH_TRACE 746 MPASS(SLIST_EMPTY(&td->td_epochs)); 747 #endif 748 749 TAILQ_REMOVE(&p->p_threads, td, td_plist); 750 p->p_numthreads--; 751 /* could clear a few other things here */ 752 /* Must NOT clear links to proc! */ 753 } 754 755 static int 756 calc_remaining(struct proc *p, int mode) 757 { 758 int remaining; 759 760 PROC_LOCK_ASSERT(p, MA_OWNED); 761 PROC_SLOCK_ASSERT(p, MA_OWNED); 762 if (mode == SINGLE_EXIT) 763 remaining = p->p_numthreads; 764 else if (mode == SINGLE_BOUNDARY) 765 remaining = p->p_numthreads - p->p_boundary_count; 766 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 767 remaining = p->p_numthreads - p->p_suspcount; 768 else 769 panic("calc_remaining: wrong mode %d", mode); 770 return (remaining); 771 } 772 773 static int 774 remain_for_mode(int mode) 775 { 776 777 return (mode == SINGLE_ALLPROC ? 0 : 1); 778 } 779 780 static int 781 weed_inhib(int mode, struct thread *td2, struct proc *p) 782 { 783 int wakeup_swapper; 784 785 PROC_LOCK_ASSERT(p, MA_OWNED); 786 PROC_SLOCK_ASSERT(p, MA_OWNED); 787 THREAD_LOCK_ASSERT(td2, MA_OWNED); 788 789 wakeup_swapper = 0; 790 791 /* 792 * Since the thread lock is dropped by the scheduler we have 793 * to retry to check for races. 794 */ 795 restart: 796 switch (mode) { 797 case SINGLE_EXIT: 798 if (TD_IS_SUSPENDED(td2)) { 799 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 800 thread_lock(td2); 801 goto restart; 802 } 803 if (TD_CAN_ABORT(td2)) { 804 wakeup_swapper |= sleepq_abort(td2, EINTR); 805 return (wakeup_swapper); 806 } 807 break; 808 case SINGLE_BOUNDARY: 809 case SINGLE_NO_EXIT: 810 if (TD_IS_SUSPENDED(td2) && 811 (td2->td_flags & TDF_BOUNDARY) == 0) { 812 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 813 thread_lock(td2); 814 goto restart; 815 } 816 if (TD_CAN_ABORT(td2)) { 817 wakeup_swapper |= sleepq_abort(td2, ERESTART); 818 return (wakeup_swapper); 819 } 820 break; 821 case SINGLE_ALLPROC: 822 /* 823 * ALLPROC suspend tries to avoid spurious EINTR for 824 * threads sleeping interruptable, by suspending the 825 * thread directly, similarly to sig_suspend_threads(). 826 * Since such sleep is not performed at the user 827 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 828 * is used to avoid immediate un-suspend. 829 */ 830 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 831 TDF_ALLPROCSUSP)) == 0) { 832 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 833 thread_lock(td2); 834 goto restart; 835 } 836 if (TD_CAN_ABORT(td2)) { 837 if ((td2->td_flags & TDF_SBDRY) == 0) { 838 thread_suspend_one(td2); 839 td2->td_flags |= TDF_ALLPROCSUSP; 840 } else { 841 wakeup_swapper |= sleepq_abort(td2, ERESTART); 842 return (wakeup_swapper); 843 } 844 } 845 break; 846 default: 847 break; 848 } 849 thread_unlock(td2); 850 return (wakeup_swapper); 851 } 852 853 /* 854 * Enforce single-threading. 855 * 856 * Returns 1 if the caller must abort (another thread is waiting to 857 * exit the process or similar). Process is locked! 858 * Returns 0 when you are successfully the only thread running. 859 * A process has successfully single threaded in the suspend mode when 860 * There are no threads in user mode. Threads in the kernel must be 861 * allowed to continue until they get to the user boundary. They may even 862 * copy out their return values and data before suspending. They may however be 863 * accelerated in reaching the user boundary as we will wake up 864 * any sleeping threads that are interruptable. (PCATCH). 865 */ 866 int 867 thread_single(struct proc *p, int mode) 868 { 869 struct thread *td; 870 struct thread *td2; 871 int remaining, wakeup_swapper; 872 873 td = curthread; 874 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 875 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 876 ("invalid mode %d", mode)); 877 /* 878 * If allowing non-ALLPROC singlethreading for non-curproc 879 * callers, calc_remaining() and remain_for_mode() should be 880 * adjusted to also account for td->td_proc != p. For now 881 * this is not implemented because it is not used. 882 */ 883 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 884 (mode != SINGLE_ALLPROC && td->td_proc == p), 885 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 886 mtx_assert(&Giant, MA_NOTOWNED); 887 PROC_LOCK_ASSERT(p, MA_OWNED); 888 889 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 890 return (0); 891 892 /* Is someone already single threading? */ 893 if (p->p_singlethread != NULL && p->p_singlethread != td) 894 return (1); 895 896 if (mode == SINGLE_EXIT) { 897 p->p_flag |= P_SINGLE_EXIT; 898 p->p_flag &= ~P_SINGLE_BOUNDARY; 899 } else { 900 p->p_flag &= ~P_SINGLE_EXIT; 901 if (mode == SINGLE_BOUNDARY) 902 p->p_flag |= P_SINGLE_BOUNDARY; 903 else 904 p->p_flag &= ~P_SINGLE_BOUNDARY; 905 } 906 if (mode == SINGLE_ALLPROC) 907 p->p_flag |= P_TOTAL_STOP; 908 p->p_flag |= P_STOPPED_SINGLE; 909 PROC_SLOCK(p); 910 p->p_singlethread = td; 911 remaining = calc_remaining(p, mode); 912 while (remaining != remain_for_mode(mode)) { 913 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 914 goto stopme; 915 wakeup_swapper = 0; 916 FOREACH_THREAD_IN_PROC(p, td2) { 917 if (td2 == td) 918 continue; 919 thread_lock(td2); 920 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 921 if (TD_IS_INHIBITED(td2)) { 922 wakeup_swapper |= weed_inhib(mode, td2, p); 923 #ifdef SMP 924 } else if (TD_IS_RUNNING(td2) && td != td2) { 925 forward_signal(td2); 926 thread_unlock(td2); 927 #endif 928 } else 929 thread_unlock(td2); 930 } 931 if (wakeup_swapper) 932 kick_proc0(); 933 remaining = calc_remaining(p, mode); 934 935 /* 936 * Maybe we suspended some threads.. was it enough? 937 */ 938 if (remaining == remain_for_mode(mode)) 939 break; 940 941 stopme: 942 /* 943 * Wake us up when everyone else has suspended. 944 * In the mean time we suspend as well. 945 */ 946 thread_suspend_switch(td, p); 947 remaining = calc_remaining(p, mode); 948 } 949 if (mode == SINGLE_EXIT) { 950 /* 951 * Convert the process to an unthreaded process. The 952 * SINGLE_EXIT is called by exit1() or execve(), in 953 * both cases other threads must be retired. 954 */ 955 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 956 p->p_singlethread = NULL; 957 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 958 959 /* 960 * Wait for any remaining threads to exit cpu_throw(). 961 */ 962 while (p->p_exitthreads != 0) { 963 PROC_SUNLOCK(p); 964 PROC_UNLOCK(p); 965 sched_relinquish(td); 966 PROC_LOCK(p); 967 PROC_SLOCK(p); 968 } 969 } else if (mode == SINGLE_BOUNDARY) { 970 /* 971 * Wait until all suspended threads are removed from 972 * the processors. The thread_suspend_check() 973 * increments p_boundary_count while it is still 974 * running, which makes it possible for the execve() 975 * to destroy vmspace while our other threads are 976 * still using the address space. 977 * 978 * We lock the thread, which is only allowed to 979 * succeed after context switch code finished using 980 * the address space. 981 */ 982 FOREACH_THREAD_IN_PROC(p, td2) { 983 if (td2 == td) 984 continue; 985 thread_lock(td2); 986 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 987 ("td %p not on boundary", td2)); 988 KASSERT(TD_IS_SUSPENDED(td2), 989 ("td %p is not suspended", td2)); 990 thread_unlock(td2); 991 } 992 } 993 PROC_SUNLOCK(p); 994 return (0); 995 } 996 997 bool 998 thread_suspend_check_needed(void) 999 { 1000 struct proc *p; 1001 struct thread *td; 1002 1003 td = curthread; 1004 p = td->td_proc; 1005 PROC_LOCK_ASSERT(p, MA_OWNED); 1006 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 1007 (td->td_dbgflags & TDB_SUSPEND) != 0)); 1008 } 1009 1010 /* 1011 * Called in from locations that can safely check to see 1012 * whether we have to suspend or at least throttle for a 1013 * single-thread event (e.g. fork). 1014 * 1015 * Such locations include userret(). 1016 * If the "return_instead" argument is non zero, the thread must be able to 1017 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 1018 * 1019 * The 'return_instead' argument tells the function if it may do a 1020 * thread_exit() or suspend, or whether the caller must abort and back 1021 * out instead. 1022 * 1023 * If the thread that set the single_threading request has set the 1024 * P_SINGLE_EXIT bit in the process flags then this call will never return 1025 * if 'return_instead' is false, but will exit. 1026 * 1027 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 1028 *---------------+--------------------+--------------------- 1029 * 0 | returns 0 | returns 0 or 1 1030 * | when ST ends | immediately 1031 *---------------+--------------------+--------------------- 1032 * 1 | thread exits | returns 1 1033 * | | immediately 1034 * 0 = thread_exit() or suspension ok, 1035 * other = return error instead of stopping the thread. 1036 * 1037 * While a full suspension is under effect, even a single threading 1038 * thread would be suspended if it made this call (but it shouldn't). 1039 * This call should only be made from places where 1040 * thread_exit() would be safe as that may be the outcome unless 1041 * return_instead is set. 1042 */ 1043 int 1044 thread_suspend_check(int return_instead) 1045 { 1046 struct thread *td; 1047 struct proc *p; 1048 int wakeup_swapper; 1049 1050 td = curthread; 1051 p = td->td_proc; 1052 mtx_assert(&Giant, MA_NOTOWNED); 1053 PROC_LOCK_ASSERT(p, MA_OWNED); 1054 while (thread_suspend_check_needed()) { 1055 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1056 KASSERT(p->p_singlethread != NULL, 1057 ("singlethread not set")); 1058 /* 1059 * The only suspension in action is a 1060 * single-threading. Single threader need not stop. 1061 * It is safe to access p->p_singlethread unlocked 1062 * because it can only be set to our address by us. 1063 */ 1064 if (p->p_singlethread == td) 1065 return (0); /* Exempt from stopping. */ 1066 } 1067 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 1068 return (EINTR); 1069 1070 /* Should we goto user boundary if we didn't come from there? */ 1071 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1072 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 1073 return (ERESTART); 1074 1075 /* 1076 * Ignore suspend requests if they are deferred. 1077 */ 1078 if ((td->td_flags & TDF_SBDRY) != 0) { 1079 KASSERT(return_instead, 1080 ("TDF_SBDRY set for unsafe thread_suspend_check")); 1081 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 1082 (TDF_SEINTR | TDF_SERESTART), 1083 ("both TDF_SEINTR and TDF_SERESTART")); 1084 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 1085 } 1086 1087 /* 1088 * If the process is waiting for us to exit, 1089 * this thread should just suicide. 1090 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 1091 */ 1092 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 1093 PROC_UNLOCK(p); 1094 1095 /* 1096 * Allow Linux emulation layer to do some work 1097 * before thread suicide. 1098 */ 1099 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 1100 (p->p_sysent->sv_thread_detach)(td); 1101 umtx_thread_exit(td); 1102 kern_thr_exit(td); 1103 panic("stopped thread did not exit"); 1104 } 1105 1106 PROC_SLOCK(p); 1107 thread_stopped(p); 1108 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1109 if (p->p_numthreads == p->p_suspcount + 1) { 1110 thread_lock(p->p_singlethread); 1111 wakeup_swapper = thread_unsuspend_one( 1112 p->p_singlethread, p, false); 1113 if (wakeup_swapper) 1114 kick_proc0(); 1115 } 1116 } 1117 PROC_UNLOCK(p); 1118 thread_lock(td); 1119 /* 1120 * When a thread suspends, it just 1121 * gets taken off all queues. 1122 */ 1123 thread_suspend_one(td); 1124 if (return_instead == 0) { 1125 p->p_boundary_count++; 1126 td->td_flags |= TDF_BOUNDARY; 1127 } 1128 PROC_SUNLOCK(p); 1129 mi_switch(SW_INVOL | SWT_SUSPEND); 1130 PROC_LOCK(p); 1131 } 1132 return (0); 1133 } 1134 1135 /* 1136 * Check for possible stops and suspensions while executing a 1137 * casueword or similar transiently failing operation. 1138 * 1139 * The sleep argument controls whether the function can handle a stop 1140 * request itself or it should return ERESTART and the request is 1141 * proceed at the kernel/user boundary in ast. 1142 * 1143 * Typically, when retrying due to casueword(9) failure (rv == 1), we 1144 * should handle the stop requests there, with exception of cases when 1145 * the thread owns a kernel resource, for instance busied the umtx 1146 * key, or when functions return immediately if thread_check_susp() 1147 * returned non-zero. On the other hand, retrying the whole lock 1148 * operation, we better not stop there but delegate the handling to 1149 * ast. 1150 * 1151 * If the request is for thread termination P_SINGLE_EXIT, we cannot 1152 * handle it at all, and simply return EINTR. 1153 */ 1154 int 1155 thread_check_susp(struct thread *td, bool sleep) 1156 { 1157 struct proc *p; 1158 int error; 1159 1160 /* 1161 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to 1162 * eventually break the lockstep loop. 1163 */ 1164 if ((td->td_flags & TDF_NEEDSUSPCHK) == 0) 1165 return (0); 1166 error = 0; 1167 p = td->td_proc; 1168 PROC_LOCK(p); 1169 if (p->p_flag & P_SINGLE_EXIT) 1170 error = EINTR; 1171 else if (P_SHOULDSTOP(p) || 1172 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) 1173 error = sleep ? thread_suspend_check(0) : ERESTART; 1174 PROC_UNLOCK(p); 1175 return (error); 1176 } 1177 1178 void 1179 thread_suspend_switch(struct thread *td, struct proc *p) 1180 { 1181 1182 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1183 PROC_LOCK_ASSERT(p, MA_OWNED); 1184 PROC_SLOCK_ASSERT(p, MA_OWNED); 1185 /* 1186 * We implement thread_suspend_one in stages here to avoid 1187 * dropping the proc lock while the thread lock is owned. 1188 */ 1189 if (p == td->td_proc) { 1190 thread_stopped(p); 1191 p->p_suspcount++; 1192 } 1193 PROC_UNLOCK(p); 1194 thread_lock(td); 1195 td->td_flags &= ~TDF_NEEDSUSPCHK; 1196 TD_SET_SUSPENDED(td); 1197 sched_sleep(td, 0); 1198 PROC_SUNLOCK(p); 1199 DROP_GIANT(); 1200 mi_switch(SW_VOL | SWT_SUSPEND); 1201 PICKUP_GIANT(); 1202 PROC_LOCK(p); 1203 PROC_SLOCK(p); 1204 } 1205 1206 void 1207 thread_suspend_one(struct thread *td) 1208 { 1209 struct proc *p; 1210 1211 p = td->td_proc; 1212 PROC_SLOCK_ASSERT(p, MA_OWNED); 1213 THREAD_LOCK_ASSERT(td, MA_OWNED); 1214 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1215 p->p_suspcount++; 1216 td->td_flags &= ~TDF_NEEDSUSPCHK; 1217 TD_SET_SUSPENDED(td); 1218 sched_sleep(td, 0); 1219 } 1220 1221 static int 1222 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1223 { 1224 1225 THREAD_LOCK_ASSERT(td, MA_OWNED); 1226 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1227 TD_CLR_SUSPENDED(td); 1228 td->td_flags &= ~TDF_ALLPROCSUSP; 1229 if (td->td_proc == p) { 1230 PROC_SLOCK_ASSERT(p, MA_OWNED); 1231 p->p_suspcount--; 1232 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1233 td->td_flags &= ~TDF_BOUNDARY; 1234 p->p_boundary_count--; 1235 } 1236 } 1237 return (setrunnable(td, 0)); 1238 } 1239 1240 /* 1241 * Allow all threads blocked by single threading to continue running. 1242 */ 1243 void 1244 thread_unsuspend(struct proc *p) 1245 { 1246 struct thread *td; 1247 int wakeup_swapper; 1248 1249 PROC_LOCK_ASSERT(p, MA_OWNED); 1250 PROC_SLOCK_ASSERT(p, MA_OWNED); 1251 wakeup_swapper = 0; 1252 if (!P_SHOULDSTOP(p)) { 1253 FOREACH_THREAD_IN_PROC(p, td) { 1254 thread_lock(td); 1255 if (TD_IS_SUSPENDED(td)) { 1256 wakeup_swapper |= thread_unsuspend_one(td, p, 1257 true); 1258 } else 1259 thread_unlock(td); 1260 } 1261 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1262 p->p_numthreads == p->p_suspcount) { 1263 /* 1264 * Stopping everything also did the job for the single 1265 * threading request. Now we've downgraded to single-threaded, 1266 * let it continue. 1267 */ 1268 if (p->p_singlethread->td_proc == p) { 1269 thread_lock(p->p_singlethread); 1270 wakeup_swapper = thread_unsuspend_one( 1271 p->p_singlethread, p, false); 1272 } 1273 } 1274 if (wakeup_swapper) 1275 kick_proc0(); 1276 } 1277 1278 /* 1279 * End the single threading mode.. 1280 */ 1281 void 1282 thread_single_end(struct proc *p, int mode) 1283 { 1284 struct thread *td; 1285 int wakeup_swapper; 1286 1287 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1288 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1289 ("invalid mode %d", mode)); 1290 PROC_LOCK_ASSERT(p, MA_OWNED); 1291 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1292 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1293 ("mode %d does not match P_TOTAL_STOP", mode)); 1294 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1295 ("thread_single_end from other thread %p %p", 1296 curthread, p->p_singlethread)); 1297 KASSERT(mode != SINGLE_BOUNDARY || 1298 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1299 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1300 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1301 P_TOTAL_STOP); 1302 PROC_SLOCK(p); 1303 p->p_singlethread = NULL; 1304 wakeup_swapper = 0; 1305 /* 1306 * If there are other threads they may now run, 1307 * unless of course there is a blanket 'stop order' 1308 * on the process. The single threader must be allowed 1309 * to continue however as this is a bad place to stop. 1310 */ 1311 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1312 FOREACH_THREAD_IN_PROC(p, td) { 1313 thread_lock(td); 1314 if (TD_IS_SUSPENDED(td)) { 1315 wakeup_swapper |= thread_unsuspend_one(td, p, 1316 mode == SINGLE_BOUNDARY); 1317 } else 1318 thread_unlock(td); 1319 } 1320 } 1321 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1322 ("inconsistent boundary count %d", p->p_boundary_count)); 1323 PROC_SUNLOCK(p); 1324 if (wakeup_swapper) 1325 kick_proc0(); 1326 } 1327 1328 /* Locate a thread by number; return with proc lock held. */ 1329 struct thread * 1330 tdfind(lwpid_t tid, pid_t pid) 1331 { 1332 #define RUN_THRESH 16 1333 struct thread *td; 1334 int run = 0; 1335 1336 td = curthread; 1337 if (td->td_tid == tid) { 1338 if (pid != -1 && td->td_proc->p_pid != pid) 1339 return (NULL); 1340 PROC_LOCK(td->td_proc); 1341 return (td); 1342 } 1343 1344 rw_rlock(&tidhash_lock); 1345 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1346 if (td->td_tid == tid) { 1347 if (pid != -1 && td->td_proc->p_pid != pid) { 1348 td = NULL; 1349 break; 1350 } 1351 PROC_LOCK(td->td_proc); 1352 if (td->td_proc->p_state == PRS_NEW) { 1353 PROC_UNLOCK(td->td_proc); 1354 td = NULL; 1355 break; 1356 } 1357 if (run > RUN_THRESH) { 1358 if (rw_try_upgrade(&tidhash_lock)) { 1359 LIST_REMOVE(td, td_hash); 1360 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1361 td, td_hash); 1362 rw_wunlock(&tidhash_lock); 1363 return (td); 1364 } 1365 } 1366 break; 1367 } 1368 run++; 1369 } 1370 rw_runlock(&tidhash_lock); 1371 return (td); 1372 } 1373 1374 void 1375 tidhash_add(struct thread *td) 1376 { 1377 rw_wlock(&tidhash_lock); 1378 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1379 rw_wunlock(&tidhash_lock); 1380 } 1381 1382 void 1383 tidhash_remove(struct thread *td) 1384 { 1385 rw_wlock(&tidhash_lock); 1386 LIST_REMOVE(td, td_hash); 1387 rw_wunlock(&tidhash_lock); 1388 } 1389