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/epoch.h> 44 #include <sys/rangelock.h> 45 #include <sys/resourcevar.h> 46 #include <sys/sdt.h> 47 #include <sys/smp.h> 48 #include <sys/sched.h> 49 #include <sys/sleepqueue.h> 50 #include <sys/selinfo.h> 51 #include <sys/syscallsubr.h> 52 #include <sys/sysent.h> 53 #include <sys/turnstile.h> 54 #include <sys/ktr.h> 55 #include <sys/rwlock.h> 56 #include <sys/umtx.h> 57 #include <sys/vmmeter.h> 58 #include <sys/cpuset.h> 59 #ifdef HWPMC_HOOKS 60 #include <sys/pmckern.h> 61 #endif 62 63 #include <security/audit/audit.h> 64 65 #include <vm/vm.h> 66 #include <vm/vm_extern.h> 67 #include <vm/uma.h> 68 #include <sys/eventhandler.h> 69 70 /* 71 * Asserts below verify the stability of struct thread and struct proc 72 * layout, as exposed by KBI to modules. On head, the KBI is allowed 73 * to drift, change to the structures must be accompanied by the 74 * assert update. 75 * 76 * On the stable branches after KBI freeze, conditions must not be 77 * violated. Typically new fields are moved to the end of the 78 * structures. 79 */ 80 #ifdef __amd64__ 81 _Static_assert(offsetof(struct thread, td_flags) == 0xfc, 82 "struct thread KBI td_flags"); 83 _Static_assert(offsetof(struct thread, td_pflags) == 0x104, 84 "struct thread KBI td_pflags"); 85 _Static_assert(offsetof(struct thread, td_frame) == 0x498, 86 "struct thread KBI td_frame"); 87 _Static_assert(offsetof(struct thread, td_emuldata) == 0x6b0, 88 "struct thread KBI td_emuldata"); 89 _Static_assert(offsetof(struct proc, p_flag) == 0xb0, 90 "struct proc KBI p_flag"); 91 _Static_assert(offsetof(struct proc, p_pid) == 0xbc, 92 "struct proc KBI p_pid"); 93 _Static_assert(offsetof(struct proc, p_filemon) == 0x3b8, 94 "struct proc KBI p_filemon"); 95 _Static_assert(offsetof(struct proc, p_comm) == 0x3d0, 96 "struct proc KBI p_comm"); 97 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4b0, 98 "struct proc KBI p_emuldata"); 99 #endif 100 #ifdef __i386__ 101 _Static_assert(offsetof(struct thread, td_flags) == 0x98, 102 "struct thread KBI td_flags"); 103 _Static_assert(offsetof(struct thread, td_pflags) == 0xa0, 104 "struct thread KBI td_pflags"); 105 _Static_assert(offsetof(struct thread, td_frame) == 0x2fc, 106 "struct thread KBI td_frame"); 107 _Static_assert(offsetof(struct thread, td_emuldata) == 0x344, 108 "struct thread KBI td_emuldata"); 109 _Static_assert(offsetof(struct proc, p_flag) == 0x68, 110 "struct proc KBI p_flag"); 111 _Static_assert(offsetof(struct proc, p_pid) == 0x74, 112 "struct proc KBI p_pid"); 113 _Static_assert(offsetof(struct proc, p_filemon) == 0x268, 114 "struct proc KBI p_filemon"); 115 _Static_assert(offsetof(struct proc, p_comm) == 0x27c, 116 "struct proc KBI p_comm"); 117 _Static_assert(offsetof(struct proc, p_emuldata) == 0x308, 118 "struct proc KBI p_emuldata"); 119 #endif 120 121 SDT_PROVIDER_DECLARE(proc); 122 SDT_PROBE_DEFINE(proc, , , lwp__exit); 123 124 /* 125 * thread related storage. 126 */ 127 static uma_zone_t thread_zone; 128 129 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 130 static struct mtx zombie_lock; 131 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 132 133 static void thread_zombie(struct thread *); 134 static int thread_unsuspend_one(struct thread *td, struct proc *p, 135 bool boundary); 136 137 #define TID_BUFFER_SIZE 1024 138 139 struct mtx tid_lock; 140 static struct unrhdr *tid_unrhdr; 141 static lwpid_t tid_buffer[TID_BUFFER_SIZE]; 142 static int tid_head, tid_tail; 143 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 144 145 struct tidhashhead *tidhashtbl; 146 u_long tidhash; 147 struct rwlock tidhash_lock; 148 149 EVENTHANDLER_LIST_DEFINE(thread_ctor); 150 EVENTHANDLER_LIST_DEFINE(thread_dtor); 151 EVENTHANDLER_LIST_DEFINE(thread_init); 152 EVENTHANDLER_LIST_DEFINE(thread_fini); 153 154 static lwpid_t 155 tid_alloc(void) 156 { 157 lwpid_t tid; 158 159 tid = alloc_unr(tid_unrhdr); 160 if (tid != -1) 161 return (tid); 162 mtx_lock(&tid_lock); 163 if (tid_head == tid_tail) { 164 mtx_unlock(&tid_lock); 165 return (-1); 166 } 167 tid = tid_buffer[tid_head]; 168 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 169 mtx_unlock(&tid_lock); 170 return (tid); 171 } 172 173 static void 174 tid_free(lwpid_t tid) 175 { 176 lwpid_t tmp_tid = -1; 177 178 mtx_lock(&tid_lock); 179 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { 180 tmp_tid = tid_buffer[tid_head]; 181 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 182 } 183 tid_buffer[tid_tail] = tid; 184 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE; 185 mtx_unlock(&tid_lock); 186 if (tmp_tid != -1) 187 free_unr(tid_unrhdr, tmp_tid); 188 } 189 190 /* 191 * Prepare a thread for use. 192 */ 193 static int 194 thread_ctor(void *mem, int size, void *arg, int flags) 195 { 196 struct thread *td; 197 198 td = (struct thread *)mem; 199 td->td_state = TDS_INACTIVE; 200 td->td_lastcpu = td->td_oncpu = NOCPU; 201 202 td->td_tid = tid_alloc(); 203 204 /* 205 * Note that td_critnest begins life as 1 because the thread is not 206 * running and is thereby implicitly waiting to be on the receiving 207 * end of a context switch. 208 */ 209 td->td_critnest = 1; 210 td->td_lend_user_pri = PRI_MAX; 211 EVENTHANDLER_DIRECT_INVOKE(thread_ctor, td); 212 #ifdef AUDIT 213 audit_thread_alloc(td); 214 #endif 215 umtx_thread_alloc(td); 216 return (0); 217 } 218 219 /* 220 * Reclaim a thread after use. 221 */ 222 static void 223 thread_dtor(void *mem, int size, void *arg) 224 { 225 struct thread *td; 226 227 td = (struct thread *)mem; 228 229 #ifdef INVARIANTS 230 /* Verify that this thread is in a safe state to free. */ 231 switch (td->td_state) { 232 case TDS_INHIBITED: 233 case TDS_RUNNING: 234 case TDS_CAN_RUN: 235 case TDS_RUNQ: 236 /* 237 * We must never unlink a thread that is in one of 238 * these states, because it is currently active. 239 */ 240 panic("bad state for thread unlinking"); 241 /* NOTREACHED */ 242 case TDS_INACTIVE: 243 break; 244 default: 245 panic("bad thread state"); 246 /* NOTREACHED */ 247 } 248 #endif 249 #ifdef AUDIT 250 audit_thread_free(td); 251 #endif 252 /* Free all OSD associated to this thread. */ 253 osd_thread_exit(td); 254 td_softdep_cleanup(td); 255 MPASS(td->td_su == NULL); 256 257 EVENTHANDLER_DIRECT_INVOKE(thread_dtor, td); 258 tid_free(td->td_tid); 259 } 260 261 /* 262 * Initialize type-stable parts of a thread (when newly created). 263 */ 264 static int 265 thread_init(void *mem, int size, int flags) 266 { 267 struct thread *td; 268 269 td = (struct thread *)mem; 270 271 td->td_sleepqueue = sleepq_alloc(); 272 td->td_turnstile = turnstile_alloc(); 273 td->td_rlqe = NULL; 274 EVENTHANDLER_DIRECT_INVOKE(thread_init, td); 275 umtx_thread_init(td); 276 td->td_kstack = 0; 277 td->td_sel = NULL; 278 return (0); 279 } 280 281 /* 282 * Tear down type-stable parts of a thread (just before being discarded). 283 */ 284 static void 285 thread_fini(void *mem, int size) 286 { 287 struct thread *td; 288 289 td = (struct thread *)mem; 290 EVENTHANDLER_DIRECT_INVOKE(thread_fini, td); 291 rlqentry_free(td->td_rlqe); 292 turnstile_free(td->td_turnstile); 293 sleepq_free(td->td_sleepqueue); 294 umtx_thread_fini(td); 295 seltdfini(td); 296 } 297 298 /* 299 * For a newly created process, 300 * link up all the structures and its initial threads etc. 301 * called from: 302 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 303 * proc_dtor() (should go away) 304 * proc_init() 305 */ 306 void 307 proc_linkup0(struct proc *p, struct thread *td) 308 { 309 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 310 proc_linkup(p, td); 311 } 312 313 void 314 proc_linkup(struct proc *p, struct thread *td) 315 { 316 317 sigqueue_init(&p->p_sigqueue, p); 318 p->p_ksi = ksiginfo_alloc(1); 319 if (p->p_ksi != NULL) { 320 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 321 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 322 } 323 LIST_INIT(&p->p_mqnotifier); 324 p->p_numthreads = 0; 325 thread_link(td, p); 326 } 327 328 /* 329 * Initialize global thread allocation resources. 330 */ 331 void 332 threadinit(void) 333 { 334 uint32_t flags; 335 336 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 337 338 /* 339 * pid_max cannot be greater than PID_MAX. 340 * leave one number for thread0. 341 */ 342 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 343 344 flags = UMA_ZONE_NOFREE; 345 #ifdef __aarch64__ 346 /* 347 * Force thread structures to be allocated from the direct map. 348 * Otherwise, superpage promotions and demotions may temporarily 349 * invalidate thread structure mappings. For most dynamically allocated 350 * structures this is not a problem, but translation faults cannot be 351 * handled without accessing curthread. 352 */ 353 flags |= UMA_ZONE_CONTIG; 354 #endif 355 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 356 thread_ctor, thread_dtor, thread_init, thread_fini, 357 32 - 1, flags); 358 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 359 rw_init(&tidhash_lock, "tidhash"); 360 } 361 362 /* 363 * Place an unused thread on the zombie list. 364 * Use the slpq as that must be unused by now. 365 */ 366 void 367 thread_zombie(struct thread *td) 368 { 369 mtx_lock_spin(&zombie_lock); 370 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 371 mtx_unlock_spin(&zombie_lock); 372 } 373 374 /* 375 * Release a thread that has exited after cpu_throw(). 376 */ 377 void 378 thread_stash(struct thread *td) 379 { 380 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 381 thread_zombie(td); 382 } 383 384 /* 385 * Reap zombie resources. 386 */ 387 void 388 thread_reap(void) 389 { 390 struct thread *td_first, *td_next; 391 392 /* 393 * Don't even bother to lock if none at this instant, 394 * we really don't care about the next instant. 395 */ 396 if (!TAILQ_EMPTY(&zombie_threads)) { 397 mtx_lock_spin(&zombie_lock); 398 td_first = TAILQ_FIRST(&zombie_threads); 399 if (td_first) 400 TAILQ_INIT(&zombie_threads); 401 mtx_unlock_spin(&zombie_lock); 402 while (td_first) { 403 td_next = TAILQ_NEXT(td_first, td_slpq); 404 thread_cow_free(td_first); 405 thread_free(td_first); 406 td_first = td_next; 407 } 408 } 409 } 410 411 /* 412 * Allocate a thread. 413 */ 414 struct thread * 415 thread_alloc(int pages) 416 { 417 struct thread *td; 418 419 thread_reap(); /* check if any zombies to get */ 420 421 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 422 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 423 if (!vm_thread_new(td, pages)) { 424 uma_zfree(thread_zone, td); 425 return (NULL); 426 } 427 cpu_thread_alloc(td); 428 return (td); 429 } 430 431 int 432 thread_alloc_stack(struct thread *td, int pages) 433 { 434 435 KASSERT(td->td_kstack == 0, 436 ("thread_alloc_stack called on a thread with kstack")); 437 if (!vm_thread_new(td, pages)) 438 return (0); 439 cpu_thread_alloc(td); 440 return (1); 441 } 442 443 /* 444 * Deallocate a thread. 445 */ 446 void 447 thread_free(struct thread *td) 448 { 449 450 lock_profile_thread_exit(td); 451 if (td->td_cpuset) 452 cpuset_rel(td->td_cpuset); 453 td->td_cpuset = NULL; 454 cpu_thread_free(td); 455 if (td->td_kstack != 0) 456 vm_thread_dispose(td); 457 callout_drain(&td->td_slpcallout); 458 uma_zfree(thread_zone, td); 459 } 460 461 void 462 thread_cow_get_proc(struct thread *newtd, struct proc *p) 463 { 464 465 PROC_LOCK_ASSERT(p, MA_OWNED); 466 newtd->td_ucred = crhold(p->p_ucred); 467 newtd->td_limit = lim_hold(p->p_limit); 468 newtd->td_cowgen = p->p_cowgen; 469 } 470 471 void 472 thread_cow_get(struct thread *newtd, struct thread *td) 473 { 474 475 newtd->td_ucred = crhold(td->td_ucred); 476 newtd->td_limit = lim_hold(td->td_limit); 477 newtd->td_cowgen = td->td_cowgen; 478 } 479 480 void 481 thread_cow_free(struct thread *td) 482 { 483 484 if (td->td_ucred != NULL) 485 crfree(td->td_ucred); 486 if (td->td_limit != NULL) 487 lim_free(td->td_limit); 488 } 489 490 void 491 thread_cow_update(struct thread *td) 492 { 493 struct proc *p; 494 struct ucred *oldcred; 495 struct plimit *oldlimit; 496 497 p = td->td_proc; 498 oldcred = NULL; 499 oldlimit = NULL; 500 PROC_LOCK(p); 501 if (td->td_ucred != p->p_ucred) { 502 oldcred = td->td_ucred; 503 td->td_ucred = crhold(p->p_ucred); 504 } 505 if (td->td_limit != p->p_limit) { 506 oldlimit = td->td_limit; 507 td->td_limit = lim_hold(p->p_limit); 508 } 509 td->td_cowgen = p->p_cowgen; 510 PROC_UNLOCK(p); 511 if (oldcred != NULL) 512 crfree(oldcred); 513 if (oldlimit != NULL) 514 lim_free(oldlimit); 515 } 516 517 /* 518 * Discard the current thread and exit from its context. 519 * Always called with scheduler locked. 520 * 521 * Because we can't free a thread while we're operating under its context, 522 * push the current thread into our CPU's deadthread holder. This means 523 * we needn't worry about someone else grabbing our context before we 524 * do a cpu_throw(). 525 */ 526 void 527 thread_exit(void) 528 { 529 uint64_t runtime, new_switchtime; 530 struct thread *td; 531 struct thread *td2; 532 struct proc *p; 533 int wakeup_swapper; 534 535 td = curthread; 536 p = td->td_proc; 537 538 PROC_SLOCK_ASSERT(p, MA_OWNED); 539 mtx_assert(&Giant, MA_NOTOWNED); 540 541 PROC_LOCK_ASSERT(p, MA_OWNED); 542 KASSERT(p != NULL, ("thread exiting without a process")); 543 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 544 (long)p->p_pid, td->td_name); 545 SDT_PROBE0(proc, , , lwp__exit); 546 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 547 548 /* 549 * drop FPU & debug register state storage, or any other 550 * architecture specific resources that 551 * would not be on a new untouched process. 552 */ 553 cpu_thread_exit(td); 554 555 /* 556 * The last thread is left attached to the process 557 * So that the whole bundle gets recycled. Skip 558 * all this stuff if we never had threads. 559 * EXIT clears all sign of other threads when 560 * it goes to single threading, so the last thread always 561 * takes the short path. 562 */ 563 if (p->p_flag & P_HADTHREADS) { 564 if (p->p_numthreads > 1) { 565 atomic_add_int(&td->td_proc->p_exitthreads, 1); 566 thread_unlink(td); 567 td2 = FIRST_THREAD_IN_PROC(p); 568 sched_exit_thread(td2, td); 569 570 /* 571 * The test below is NOT true if we are the 572 * sole exiting thread. P_STOPPED_SINGLE is unset 573 * in exit1() after it is the only survivor. 574 */ 575 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 576 if (p->p_numthreads == p->p_suspcount) { 577 thread_lock(p->p_singlethread); 578 wakeup_swapper = thread_unsuspend_one( 579 p->p_singlethread, p, false); 580 if (wakeup_swapper) 581 kick_proc0(); 582 } 583 } 584 585 PCPU_SET(deadthread, td); 586 } else { 587 /* 588 * The last thread is exiting.. but not through exit() 589 */ 590 panic ("thread_exit: Last thread exiting on its own"); 591 } 592 } 593 #ifdef HWPMC_HOOKS 594 /* 595 * If this thread is part of a process that is being tracked by hwpmc(4), 596 * inform the module of the thread's impending exit. 597 */ 598 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) { 599 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 600 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL); 601 } else if (PMC_SYSTEM_SAMPLING_ACTIVE()) 602 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL); 603 #endif 604 PROC_UNLOCK(p); 605 PROC_STATLOCK(p); 606 thread_lock(td); 607 PROC_SUNLOCK(p); 608 609 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 610 new_switchtime = cpu_ticks(); 611 runtime = new_switchtime - PCPU_GET(switchtime); 612 td->td_runtime += runtime; 613 td->td_incruntime += runtime; 614 PCPU_SET(switchtime, new_switchtime); 615 PCPU_SET(switchticks, ticks); 616 VM_CNT_INC(v_swtch); 617 618 /* Save our resource usage in our process. */ 619 td->td_ru.ru_nvcsw++; 620 ruxagg_locked(p, td); 621 rucollect(&p->p_ru, &td->td_ru); 622 PROC_STATUNLOCK(p); 623 624 td->td_state = TDS_INACTIVE; 625 #ifdef WITNESS 626 witness_thread_exit(td); 627 #endif 628 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 629 sched_throw(td); 630 panic("I'm a teapot!"); 631 /* NOTREACHED */ 632 } 633 634 /* 635 * Do any thread specific cleanups that may be needed in wait() 636 * called with Giant, proc and schedlock not held. 637 */ 638 void 639 thread_wait(struct proc *p) 640 { 641 struct thread *td; 642 643 mtx_assert(&Giant, MA_NOTOWNED); 644 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 645 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 646 td = FIRST_THREAD_IN_PROC(p); 647 /* Lock the last thread so we spin until it exits cpu_throw(). */ 648 thread_lock(td); 649 thread_unlock(td); 650 lock_profile_thread_exit(td); 651 cpuset_rel(td->td_cpuset); 652 td->td_cpuset = NULL; 653 cpu_thread_clean(td); 654 thread_cow_free(td); 655 callout_drain(&td->td_slpcallout); 656 thread_reap(); /* check for zombie threads etc. */ 657 } 658 659 /* 660 * Link a thread to a process. 661 * set up anything that needs to be initialized for it to 662 * be used by the process. 663 */ 664 void 665 thread_link(struct thread *td, struct proc *p) 666 { 667 668 /* 669 * XXX This can't be enabled because it's called for proc0 before 670 * its lock has been created. 671 * PROC_LOCK_ASSERT(p, MA_OWNED); 672 */ 673 td->td_state = TDS_INACTIVE; 674 td->td_proc = p; 675 td->td_flags = TDF_INMEM; 676 677 LIST_INIT(&td->td_contested); 678 LIST_INIT(&td->td_lprof[0]); 679 LIST_INIT(&td->td_lprof[1]); 680 #ifdef EPOCH_TRACE 681 SLIST_INIT(&td->td_epochs); 682 #endif 683 sigqueue_init(&td->td_sigqueue, p); 684 callout_init(&td->td_slpcallout, 1); 685 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 686 p->p_numthreads++; 687 } 688 689 /* 690 * Called from: 691 * thread_exit() 692 */ 693 void 694 thread_unlink(struct thread *td) 695 { 696 struct proc *p = td->td_proc; 697 698 PROC_LOCK_ASSERT(p, MA_OWNED); 699 #ifdef EPOCH_TRACE 700 MPASS(SLIST_EMPTY(&td->td_epochs)); 701 #endif 702 703 TAILQ_REMOVE(&p->p_threads, td, td_plist); 704 p->p_numthreads--; 705 /* could clear a few other things here */ 706 /* Must NOT clear links to proc! */ 707 } 708 709 static int 710 calc_remaining(struct proc *p, int mode) 711 { 712 int remaining; 713 714 PROC_LOCK_ASSERT(p, MA_OWNED); 715 PROC_SLOCK_ASSERT(p, MA_OWNED); 716 if (mode == SINGLE_EXIT) 717 remaining = p->p_numthreads; 718 else if (mode == SINGLE_BOUNDARY) 719 remaining = p->p_numthreads - p->p_boundary_count; 720 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 721 remaining = p->p_numthreads - p->p_suspcount; 722 else 723 panic("calc_remaining: wrong mode %d", mode); 724 return (remaining); 725 } 726 727 static int 728 remain_for_mode(int mode) 729 { 730 731 return (mode == SINGLE_ALLPROC ? 0 : 1); 732 } 733 734 static int 735 weed_inhib(int mode, struct thread *td2, struct proc *p) 736 { 737 int wakeup_swapper; 738 739 PROC_LOCK_ASSERT(p, MA_OWNED); 740 PROC_SLOCK_ASSERT(p, MA_OWNED); 741 THREAD_LOCK_ASSERT(td2, MA_OWNED); 742 743 wakeup_swapper = 0; 744 745 /* 746 * Since the thread lock is dropped by the scheduler we have 747 * to retry to check for races. 748 */ 749 restart: 750 switch (mode) { 751 case SINGLE_EXIT: 752 if (TD_IS_SUSPENDED(td2)) { 753 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 754 thread_lock(td2); 755 goto restart; 756 } 757 if (TD_CAN_ABORT(td2)) { 758 wakeup_swapper |= sleepq_abort(td2, EINTR); 759 return (wakeup_swapper); 760 } 761 break; 762 case SINGLE_BOUNDARY: 763 case SINGLE_NO_EXIT: 764 if (TD_IS_SUSPENDED(td2) && 765 (td2->td_flags & TDF_BOUNDARY) == 0) { 766 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 767 thread_lock(td2); 768 goto restart; 769 } 770 if (TD_CAN_ABORT(td2)) { 771 wakeup_swapper |= sleepq_abort(td2, ERESTART); 772 return (wakeup_swapper); 773 } 774 break; 775 case SINGLE_ALLPROC: 776 /* 777 * ALLPROC suspend tries to avoid spurious EINTR for 778 * threads sleeping interruptable, by suspending the 779 * thread directly, similarly to sig_suspend_threads(). 780 * Since such sleep is not performed at the user 781 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 782 * is used to avoid immediate un-suspend. 783 */ 784 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 785 TDF_ALLPROCSUSP)) == 0) { 786 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 787 thread_lock(td2); 788 goto restart; 789 } 790 if (TD_CAN_ABORT(td2)) { 791 if ((td2->td_flags & TDF_SBDRY) == 0) { 792 thread_suspend_one(td2); 793 td2->td_flags |= TDF_ALLPROCSUSP; 794 } else { 795 wakeup_swapper |= sleepq_abort(td2, ERESTART); 796 return (wakeup_swapper); 797 } 798 } 799 break; 800 default: 801 break; 802 } 803 thread_unlock(td2); 804 return (wakeup_swapper); 805 } 806 807 /* 808 * Enforce single-threading. 809 * 810 * Returns 1 if the caller must abort (another thread is waiting to 811 * exit the process or similar). Process is locked! 812 * Returns 0 when you are successfully the only thread running. 813 * A process has successfully single threaded in the suspend mode when 814 * There are no threads in user mode. Threads in the kernel must be 815 * allowed to continue until they get to the user boundary. They may even 816 * copy out their return values and data before suspending. They may however be 817 * accelerated in reaching the user boundary as we will wake up 818 * any sleeping threads that are interruptable. (PCATCH). 819 */ 820 int 821 thread_single(struct proc *p, int mode) 822 { 823 struct thread *td; 824 struct thread *td2; 825 int remaining, wakeup_swapper; 826 827 td = curthread; 828 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 829 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 830 ("invalid mode %d", mode)); 831 /* 832 * If allowing non-ALLPROC singlethreading for non-curproc 833 * callers, calc_remaining() and remain_for_mode() should be 834 * adjusted to also account for td->td_proc != p. For now 835 * this is not implemented because it is not used. 836 */ 837 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 838 (mode != SINGLE_ALLPROC && td->td_proc == p), 839 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 840 mtx_assert(&Giant, MA_NOTOWNED); 841 PROC_LOCK_ASSERT(p, MA_OWNED); 842 843 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 844 return (0); 845 846 /* Is someone already single threading? */ 847 if (p->p_singlethread != NULL && p->p_singlethread != td) 848 return (1); 849 850 if (mode == SINGLE_EXIT) { 851 p->p_flag |= P_SINGLE_EXIT; 852 p->p_flag &= ~P_SINGLE_BOUNDARY; 853 } else { 854 p->p_flag &= ~P_SINGLE_EXIT; 855 if (mode == SINGLE_BOUNDARY) 856 p->p_flag |= P_SINGLE_BOUNDARY; 857 else 858 p->p_flag &= ~P_SINGLE_BOUNDARY; 859 } 860 if (mode == SINGLE_ALLPROC) 861 p->p_flag |= P_TOTAL_STOP; 862 p->p_flag |= P_STOPPED_SINGLE; 863 PROC_SLOCK(p); 864 p->p_singlethread = td; 865 remaining = calc_remaining(p, mode); 866 while (remaining != remain_for_mode(mode)) { 867 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 868 goto stopme; 869 wakeup_swapper = 0; 870 FOREACH_THREAD_IN_PROC(p, td2) { 871 if (td2 == td) 872 continue; 873 thread_lock(td2); 874 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 875 if (TD_IS_INHIBITED(td2)) { 876 wakeup_swapper |= weed_inhib(mode, td2, p); 877 #ifdef SMP 878 } else if (TD_IS_RUNNING(td2) && td != td2) { 879 forward_signal(td2); 880 thread_unlock(td2); 881 #endif 882 } else 883 thread_unlock(td2); 884 } 885 if (wakeup_swapper) 886 kick_proc0(); 887 remaining = calc_remaining(p, mode); 888 889 /* 890 * Maybe we suspended some threads.. was it enough? 891 */ 892 if (remaining == remain_for_mode(mode)) 893 break; 894 895 stopme: 896 /* 897 * Wake us up when everyone else has suspended. 898 * In the mean time we suspend as well. 899 */ 900 thread_suspend_switch(td, p); 901 remaining = calc_remaining(p, mode); 902 } 903 if (mode == SINGLE_EXIT) { 904 /* 905 * Convert the process to an unthreaded process. The 906 * SINGLE_EXIT is called by exit1() or execve(), in 907 * both cases other threads must be retired. 908 */ 909 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 910 p->p_singlethread = NULL; 911 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 912 913 /* 914 * Wait for any remaining threads to exit cpu_throw(). 915 */ 916 while (p->p_exitthreads != 0) { 917 PROC_SUNLOCK(p); 918 PROC_UNLOCK(p); 919 sched_relinquish(td); 920 PROC_LOCK(p); 921 PROC_SLOCK(p); 922 } 923 } else if (mode == SINGLE_BOUNDARY) { 924 /* 925 * Wait until all suspended threads are removed from 926 * the processors. The thread_suspend_check() 927 * increments p_boundary_count while it is still 928 * running, which makes it possible for the execve() 929 * to destroy vmspace while our other threads are 930 * still using the address space. 931 * 932 * We lock the thread, which is only allowed to 933 * succeed after context switch code finished using 934 * the address space. 935 */ 936 FOREACH_THREAD_IN_PROC(p, td2) { 937 if (td2 == td) 938 continue; 939 thread_lock(td2); 940 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 941 ("td %p not on boundary", td2)); 942 KASSERT(TD_IS_SUSPENDED(td2), 943 ("td %p is not suspended", td2)); 944 thread_unlock(td2); 945 } 946 } 947 PROC_SUNLOCK(p); 948 return (0); 949 } 950 951 bool 952 thread_suspend_check_needed(void) 953 { 954 struct proc *p; 955 struct thread *td; 956 957 td = curthread; 958 p = td->td_proc; 959 PROC_LOCK_ASSERT(p, MA_OWNED); 960 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 961 (td->td_dbgflags & TDB_SUSPEND) != 0)); 962 } 963 964 /* 965 * Called in from locations that can safely check to see 966 * whether we have to suspend or at least throttle for a 967 * single-thread event (e.g. fork). 968 * 969 * Such locations include userret(). 970 * If the "return_instead" argument is non zero, the thread must be able to 971 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 972 * 973 * The 'return_instead' argument tells the function if it may do a 974 * thread_exit() or suspend, or whether the caller must abort and back 975 * out instead. 976 * 977 * If the thread that set the single_threading request has set the 978 * P_SINGLE_EXIT bit in the process flags then this call will never return 979 * if 'return_instead' is false, but will exit. 980 * 981 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 982 *---------------+--------------------+--------------------- 983 * 0 | returns 0 | returns 0 or 1 984 * | when ST ends | immediately 985 *---------------+--------------------+--------------------- 986 * 1 | thread exits | returns 1 987 * | | immediately 988 * 0 = thread_exit() or suspension ok, 989 * other = return error instead of stopping the thread. 990 * 991 * While a full suspension is under effect, even a single threading 992 * thread would be suspended if it made this call (but it shouldn't). 993 * This call should only be made from places where 994 * thread_exit() would be safe as that may be the outcome unless 995 * return_instead is set. 996 */ 997 int 998 thread_suspend_check(int return_instead) 999 { 1000 struct thread *td; 1001 struct proc *p; 1002 int wakeup_swapper; 1003 1004 td = curthread; 1005 p = td->td_proc; 1006 mtx_assert(&Giant, MA_NOTOWNED); 1007 PROC_LOCK_ASSERT(p, MA_OWNED); 1008 while (thread_suspend_check_needed()) { 1009 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1010 KASSERT(p->p_singlethread != NULL, 1011 ("singlethread not set")); 1012 /* 1013 * The only suspension in action is a 1014 * single-threading. Single threader need not stop. 1015 * It is safe to access p->p_singlethread unlocked 1016 * because it can only be set to our address by us. 1017 */ 1018 if (p->p_singlethread == td) 1019 return (0); /* Exempt from stopping. */ 1020 } 1021 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 1022 return (EINTR); 1023 1024 /* Should we goto user boundary if we didn't come from there? */ 1025 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1026 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 1027 return (ERESTART); 1028 1029 /* 1030 * Ignore suspend requests if they are deferred. 1031 */ 1032 if ((td->td_flags & TDF_SBDRY) != 0) { 1033 KASSERT(return_instead, 1034 ("TDF_SBDRY set for unsafe thread_suspend_check")); 1035 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 1036 (TDF_SEINTR | TDF_SERESTART), 1037 ("both TDF_SEINTR and TDF_SERESTART")); 1038 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 1039 } 1040 1041 /* 1042 * If the process is waiting for us to exit, 1043 * this thread should just suicide. 1044 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 1045 */ 1046 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 1047 PROC_UNLOCK(p); 1048 1049 /* 1050 * Allow Linux emulation layer to do some work 1051 * before thread suicide. 1052 */ 1053 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 1054 (p->p_sysent->sv_thread_detach)(td); 1055 umtx_thread_exit(td); 1056 kern_thr_exit(td); 1057 panic("stopped thread did not exit"); 1058 } 1059 1060 PROC_SLOCK(p); 1061 thread_stopped(p); 1062 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1063 if (p->p_numthreads == p->p_suspcount + 1) { 1064 thread_lock(p->p_singlethread); 1065 wakeup_swapper = thread_unsuspend_one( 1066 p->p_singlethread, p, false); 1067 if (wakeup_swapper) 1068 kick_proc0(); 1069 } 1070 } 1071 PROC_UNLOCK(p); 1072 thread_lock(td); 1073 /* 1074 * When a thread suspends, it just 1075 * gets taken off all queues. 1076 */ 1077 thread_suspend_one(td); 1078 if (return_instead == 0) { 1079 p->p_boundary_count++; 1080 td->td_flags |= TDF_BOUNDARY; 1081 } 1082 PROC_SUNLOCK(p); 1083 mi_switch(SW_INVOL | SWT_SUSPEND); 1084 PROC_LOCK(p); 1085 } 1086 return (0); 1087 } 1088 1089 /* 1090 * Check for possible stops and suspensions while executing a 1091 * casueword or similar transiently failing operation. 1092 * 1093 * The sleep argument controls whether the function can handle a stop 1094 * request itself or it should return ERESTART and the request is 1095 * proceed at the kernel/user boundary in ast. 1096 * 1097 * Typically, when retrying due to casueword(9) failure (rv == 1), we 1098 * should handle the stop requests there, with exception of cases when 1099 * the thread owns a kernel resource, for instance busied the umtx 1100 * key, or when functions return immediately if thread_check_susp() 1101 * returned non-zero. On the other hand, retrying the whole lock 1102 * operation, we better not stop there but delegate the handling to 1103 * ast. 1104 * 1105 * If the request is for thread termination P_SINGLE_EXIT, we cannot 1106 * handle it at all, and simply return EINTR. 1107 */ 1108 int 1109 thread_check_susp(struct thread *td, bool sleep) 1110 { 1111 struct proc *p; 1112 int error; 1113 1114 /* 1115 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to 1116 * eventually break the lockstep loop. 1117 */ 1118 if ((td->td_flags & TDF_NEEDSUSPCHK) == 0) 1119 return (0); 1120 error = 0; 1121 p = td->td_proc; 1122 PROC_LOCK(p); 1123 if (p->p_flag & P_SINGLE_EXIT) 1124 error = EINTR; 1125 else if (P_SHOULDSTOP(p) || 1126 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) 1127 error = sleep ? thread_suspend_check(0) : ERESTART; 1128 PROC_UNLOCK(p); 1129 return (error); 1130 } 1131 1132 void 1133 thread_suspend_switch(struct thread *td, struct proc *p) 1134 { 1135 1136 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1137 PROC_LOCK_ASSERT(p, MA_OWNED); 1138 PROC_SLOCK_ASSERT(p, MA_OWNED); 1139 /* 1140 * We implement thread_suspend_one in stages here to avoid 1141 * dropping the proc lock while the thread lock is owned. 1142 */ 1143 if (p == td->td_proc) { 1144 thread_stopped(p); 1145 p->p_suspcount++; 1146 } 1147 PROC_UNLOCK(p); 1148 thread_lock(td); 1149 td->td_flags &= ~TDF_NEEDSUSPCHK; 1150 TD_SET_SUSPENDED(td); 1151 sched_sleep(td, 0); 1152 PROC_SUNLOCK(p); 1153 DROP_GIANT(); 1154 mi_switch(SW_VOL | SWT_SUSPEND); 1155 PICKUP_GIANT(); 1156 PROC_LOCK(p); 1157 PROC_SLOCK(p); 1158 } 1159 1160 void 1161 thread_suspend_one(struct thread *td) 1162 { 1163 struct proc *p; 1164 1165 p = td->td_proc; 1166 PROC_SLOCK_ASSERT(p, MA_OWNED); 1167 THREAD_LOCK_ASSERT(td, MA_OWNED); 1168 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1169 p->p_suspcount++; 1170 td->td_flags &= ~TDF_NEEDSUSPCHK; 1171 TD_SET_SUSPENDED(td); 1172 sched_sleep(td, 0); 1173 } 1174 1175 static int 1176 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1177 { 1178 1179 THREAD_LOCK_ASSERT(td, MA_OWNED); 1180 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1181 TD_CLR_SUSPENDED(td); 1182 td->td_flags &= ~TDF_ALLPROCSUSP; 1183 if (td->td_proc == p) { 1184 PROC_SLOCK_ASSERT(p, MA_OWNED); 1185 p->p_suspcount--; 1186 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1187 td->td_flags &= ~TDF_BOUNDARY; 1188 p->p_boundary_count--; 1189 } 1190 } 1191 return (setrunnable(td, 0)); 1192 } 1193 1194 /* 1195 * Allow all threads blocked by single threading to continue running. 1196 */ 1197 void 1198 thread_unsuspend(struct proc *p) 1199 { 1200 struct thread *td; 1201 int wakeup_swapper; 1202 1203 PROC_LOCK_ASSERT(p, MA_OWNED); 1204 PROC_SLOCK_ASSERT(p, MA_OWNED); 1205 wakeup_swapper = 0; 1206 if (!P_SHOULDSTOP(p)) { 1207 FOREACH_THREAD_IN_PROC(p, td) { 1208 thread_lock(td); 1209 if (TD_IS_SUSPENDED(td)) { 1210 wakeup_swapper |= thread_unsuspend_one(td, p, 1211 true); 1212 } else 1213 thread_unlock(td); 1214 } 1215 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1216 p->p_numthreads == p->p_suspcount) { 1217 /* 1218 * Stopping everything also did the job for the single 1219 * threading request. Now we've downgraded to single-threaded, 1220 * let it continue. 1221 */ 1222 if (p->p_singlethread->td_proc == p) { 1223 thread_lock(p->p_singlethread); 1224 wakeup_swapper = thread_unsuspend_one( 1225 p->p_singlethread, p, false); 1226 } 1227 } 1228 if (wakeup_swapper) 1229 kick_proc0(); 1230 } 1231 1232 /* 1233 * End the single threading mode.. 1234 */ 1235 void 1236 thread_single_end(struct proc *p, int mode) 1237 { 1238 struct thread *td; 1239 int wakeup_swapper; 1240 1241 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1242 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1243 ("invalid mode %d", mode)); 1244 PROC_LOCK_ASSERT(p, MA_OWNED); 1245 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1246 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1247 ("mode %d does not match P_TOTAL_STOP", mode)); 1248 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1249 ("thread_single_end from other thread %p %p", 1250 curthread, p->p_singlethread)); 1251 KASSERT(mode != SINGLE_BOUNDARY || 1252 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1253 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1254 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1255 P_TOTAL_STOP); 1256 PROC_SLOCK(p); 1257 p->p_singlethread = NULL; 1258 wakeup_swapper = 0; 1259 /* 1260 * If there are other threads they may now run, 1261 * unless of course there is a blanket 'stop order' 1262 * on the process. The single threader must be allowed 1263 * to continue however as this is a bad place to stop. 1264 */ 1265 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1266 FOREACH_THREAD_IN_PROC(p, td) { 1267 thread_lock(td); 1268 if (TD_IS_SUSPENDED(td)) { 1269 wakeup_swapper |= thread_unsuspend_one(td, p, 1270 mode == SINGLE_BOUNDARY); 1271 } else 1272 thread_unlock(td); 1273 } 1274 } 1275 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1276 ("inconsistent boundary count %d", p->p_boundary_count)); 1277 PROC_SUNLOCK(p); 1278 if (wakeup_swapper) 1279 kick_proc0(); 1280 } 1281 1282 struct thread * 1283 thread_find(struct proc *p, lwpid_t tid) 1284 { 1285 struct thread *td; 1286 1287 PROC_LOCK_ASSERT(p, MA_OWNED); 1288 FOREACH_THREAD_IN_PROC(p, td) { 1289 if (td->td_tid == tid) 1290 break; 1291 } 1292 return (td); 1293 } 1294 1295 /* Locate a thread by number; return with proc lock held. */ 1296 struct thread * 1297 tdfind(lwpid_t tid, pid_t pid) 1298 { 1299 #define RUN_THRESH 16 1300 struct thread *td; 1301 int run = 0; 1302 1303 rw_rlock(&tidhash_lock); 1304 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1305 if (td->td_tid == tid) { 1306 if (pid != -1 && td->td_proc->p_pid != pid) { 1307 td = NULL; 1308 break; 1309 } 1310 PROC_LOCK(td->td_proc); 1311 if (td->td_proc->p_state == PRS_NEW) { 1312 PROC_UNLOCK(td->td_proc); 1313 td = NULL; 1314 break; 1315 } 1316 if (run > RUN_THRESH) { 1317 if (rw_try_upgrade(&tidhash_lock)) { 1318 LIST_REMOVE(td, td_hash); 1319 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1320 td, td_hash); 1321 rw_wunlock(&tidhash_lock); 1322 return (td); 1323 } 1324 } 1325 break; 1326 } 1327 run++; 1328 } 1329 rw_runlock(&tidhash_lock); 1330 return (td); 1331 } 1332 1333 void 1334 tidhash_add(struct thread *td) 1335 { 1336 rw_wlock(&tidhash_lock); 1337 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1338 rw_wunlock(&tidhash_lock); 1339 } 1340 1341 void 1342 tidhash_remove(struct thread *td) 1343 { 1344 rw_wlock(&tidhash_lock); 1345 LIST_REMOVE(td, td_hash); 1346 rw_wunlock(&tidhash_lock); 1347 } 1348