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) == 0x4a8, 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) == 0x304, 106 "struct thread KBI td_frame"); 107 _Static_assert(offsetof(struct thread, td_emuldata) == 0x348, 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_realucred = crcowget(p->p_ucred); 467 newtd->td_ucred = newtd->td_realucred; 468 newtd->td_limit = lim_hold(p->p_limit); 469 newtd->td_cowgen = p->p_cowgen; 470 } 471 472 void 473 thread_cow_get(struct thread *newtd, struct thread *td) 474 { 475 476 MPASS(td->td_realucred == td->td_ucred); 477 newtd->td_realucred = crcowget(td->td_realucred); 478 newtd->td_ucred = newtd->td_realucred; 479 newtd->td_limit = lim_hold(td->td_limit); 480 newtd->td_cowgen = td->td_cowgen; 481 } 482 483 void 484 thread_cow_free(struct thread *td) 485 { 486 487 if (td->td_realucred != NULL) 488 crcowfree(td); 489 if (td->td_limit != NULL) 490 lim_free(td->td_limit); 491 } 492 493 void 494 thread_cow_update(struct thread *td) 495 { 496 struct proc *p; 497 struct ucred *oldcred; 498 struct plimit *oldlimit; 499 500 p = td->td_proc; 501 oldlimit = NULL; 502 PROC_LOCK(p); 503 oldcred = crcowsync(); 504 if (td->td_limit != p->p_limit) { 505 oldlimit = td->td_limit; 506 td->td_limit = lim_hold(p->p_limit); 507 } 508 td->td_cowgen = p->p_cowgen; 509 PROC_UNLOCK(p); 510 if (oldcred != NULL) 511 crfree(oldcred); 512 if (oldlimit != NULL) 513 lim_free(oldlimit); 514 } 515 516 /* 517 * Discard the current thread and exit from its context. 518 * Always called with scheduler locked. 519 * 520 * Because we can't free a thread while we're operating under its context, 521 * push the current thread into our CPU's deadthread holder. This means 522 * we needn't worry about someone else grabbing our context before we 523 * do a cpu_throw(). 524 */ 525 void 526 thread_exit(void) 527 { 528 uint64_t runtime, new_switchtime; 529 struct thread *td; 530 struct thread *td2; 531 struct proc *p; 532 int wakeup_swapper; 533 534 td = curthread; 535 p = td->td_proc; 536 537 PROC_SLOCK_ASSERT(p, MA_OWNED); 538 mtx_assert(&Giant, MA_NOTOWNED); 539 540 PROC_LOCK_ASSERT(p, MA_OWNED); 541 KASSERT(p != NULL, ("thread exiting without a process")); 542 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 543 (long)p->p_pid, td->td_name); 544 SDT_PROBE0(proc, , , lwp__exit); 545 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 546 547 /* 548 * drop FPU & debug register state storage, or any other 549 * architecture specific resources that 550 * would not be on a new untouched process. 551 */ 552 cpu_thread_exit(td); 553 554 /* 555 * The last thread is left attached to the process 556 * So that the whole bundle gets recycled. Skip 557 * all this stuff if we never had threads. 558 * EXIT clears all sign of other threads when 559 * it goes to single threading, so the last thread always 560 * takes the short path. 561 */ 562 if (p->p_flag & P_HADTHREADS) { 563 if (p->p_numthreads > 1) { 564 atomic_add_int(&td->td_proc->p_exitthreads, 1); 565 thread_unlink(td); 566 td2 = FIRST_THREAD_IN_PROC(p); 567 sched_exit_thread(td2, td); 568 569 /* 570 * The test below is NOT true if we are the 571 * sole exiting thread. P_STOPPED_SINGLE is unset 572 * in exit1() after it is the only survivor. 573 */ 574 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 575 if (p->p_numthreads == p->p_suspcount) { 576 thread_lock(p->p_singlethread); 577 wakeup_swapper = thread_unsuspend_one( 578 p->p_singlethread, p, false); 579 if (wakeup_swapper) 580 kick_proc0(); 581 } 582 } 583 584 PCPU_SET(deadthread, td); 585 } else { 586 /* 587 * The last thread is exiting.. but not through exit() 588 */ 589 panic ("thread_exit: Last thread exiting on its own"); 590 } 591 } 592 #ifdef HWPMC_HOOKS 593 /* 594 * If this thread is part of a process that is being tracked by hwpmc(4), 595 * inform the module of the thread's impending exit. 596 */ 597 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) { 598 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 599 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT, NULL); 600 } else if (PMC_SYSTEM_SAMPLING_ACTIVE()) 601 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_THR_EXIT_LOG, NULL); 602 #endif 603 PROC_UNLOCK(p); 604 PROC_STATLOCK(p); 605 thread_lock(td); 606 PROC_SUNLOCK(p); 607 608 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 609 new_switchtime = cpu_ticks(); 610 runtime = new_switchtime - PCPU_GET(switchtime); 611 td->td_runtime += runtime; 612 td->td_incruntime += runtime; 613 PCPU_SET(switchtime, new_switchtime); 614 PCPU_SET(switchticks, ticks); 615 VM_CNT_INC(v_swtch); 616 617 /* Save our resource usage in our process. */ 618 td->td_ru.ru_nvcsw++; 619 ruxagg_locked(p, td); 620 rucollect(&p->p_ru, &td->td_ru); 621 PROC_STATUNLOCK(p); 622 623 td->td_state = TDS_INACTIVE; 624 #ifdef WITNESS 625 witness_thread_exit(td); 626 #endif 627 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 628 sched_throw(td); 629 panic("I'm a teapot!"); 630 /* NOTREACHED */ 631 } 632 633 /* 634 * Do any thread specific cleanups that may be needed in wait() 635 * called with Giant, proc and schedlock not held. 636 */ 637 void 638 thread_wait(struct proc *p) 639 { 640 struct thread *td; 641 642 mtx_assert(&Giant, MA_NOTOWNED); 643 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 644 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 645 td = FIRST_THREAD_IN_PROC(p); 646 /* Lock the last thread so we spin until it exits cpu_throw(). */ 647 thread_lock(td); 648 thread_unlock(td); 649 lock_profile_thread_exit(td); 650 cpuset_rel(td->td_cpuset); 651 td->td_cpuset = NULL; 652 cpu_thread_clean(td); 653 thread_cow_free(td); 654 callout_drain(&td->td_slpcallout); 655 thread_reap(); /* check for zombie threads etc. */ 656 } 657 658 /* 659 * Link a thread to a process. 660 * set up anything that needs to be initialized for it to 661 * be used by the process. 662 */ 663 void 664 thread_link(struct thread *td, struct proc *p) 665 { 666 667 /* 668 * XXX This can't be enabled because it's called for proc0 before 669 * its lock has been created. 670 * PROC_LOCK_ASSERT(p, MA_OWNED); 671 */ 672 td->td_state = TDS_INACTIVE; 673 td->td_proc = p; 674 td->td_flags = TDF_INMEM; 675 676 LIST_INIT(&td->td_contested); 677 LIST_INIT(&td->td_lprof[0]); 678 LIST_INIT(&td->td_lprof[1]); 679 #ifdef EPOCH_TRACE 680 SLIST_INIT(&td->td_epochs); 681 #endif 682 sigqueue_init(&td->td_sigqueue, p); 683 callout_init(&td->td_slpcallout, 1); 684 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 685 p->p_numthreads++; 686 } 687 688 /* 689 * Called from: 690 * thread_exit() 691 */ 692 void 693 thread_unlink(struct thread *td) 694 { 695 struct proc *p = td->td_proc; 696 697 PROC_LOCK_ASSERT(p, MA_OWNED); 698 #ifdef EPOCH_TRACE 699 MPASS(SLIST_EMPTY(&td->td_epochs)); 700 #endif 701 702 TAILQ_REMOVE(&p->p_threads, td, td_plist); 703 p->p_numthreads--; 704 /* could clear a few other things here */ 705 /* Must NOT clear links to proc! */ 706 } 707 708 static int 709 calc_remaining(struct proc *p, int mode) 710 { 711 int remaining; 712 713 PROC_LOCK_ASSERT(p, MA_OWNED); 714 PROC_SLOCK_ASSERT(p, MA_OWNED); 715 if (mode == SINGLE_EXIT) 716 remaining = p->p_numthreads; 717 else if (mode == SINGLE_BOUNDARY) 718 remaining = p->p_numthreads - p->p_boundary_count; 719 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 720 remaining = p->p_numthreads - p->p_suspcount; 721 else 722 panic("calc_remaining: wrong mode %d", mode); 723 return (remaining); 724 } 725 726 static int 727 remain_for_mode(int mode) 728 { 729 730 return (mode == SINGLE_ALLPROC ? 0 : 1); 731 } 732 733 static int 734 weed_inhib(int mode, struct thread *td2, struct proc *p) 735 { 736 int wakeup_swapper; 737 738 PROC_LOCK_ASSERT(p, MA_OWNED); 739 PROC_SLOCK_ASSERT(p, MA_OWNED); 740 THREAD_LOCK_ASSERT(td2, MA_OWNED); 741 742 wakeup_swapper = 0; 743 744 /* 745 * Since the thread lock is dropped by the scheduler we have 746 * to retry to check for races. 747 */ 748 restart: 749 switch (mode) { 750 case SINGLE_EXIT: 751 if (TD_IS_SUSPENDED(td2)) { 752 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 753 thread_lock(td2); 754 goto restart; 755 } 756 if (TD_CAN_ABORT(td2)) { 757 wakeup_swapper |= sleepq_abort(td2, EINTR); 758 return (wakeup_swapper); 759 } 760 break; 761 case SINGLE_BOUNDARY: 762 case SINGLE_NO_EXIT: 763 if (TD_IS_SUSPENDED(td2) && 764 (td2->td_flags & TDF_BOUNDARY) == 0) { 765 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 766 thread_lock(td2); 767 goto restart; 768 } 769 if (TD_CAN_ABORT(td2)) { 770 wakeup_swapper |= sleepq_abort(td2, ERESTART); 771 return (wakeup_swapper); 772 } 773 break; 774 case SINGLE_ALLPROC: 775 /* 776 * ALLPROC suspend tries to avoid spurious EINTR for 777 * threads sleeping interruptable, by suspending the 778 * thread directly, similarly to sig_suspend_threads(). 779 * Since such sleep is not performed at the user 780 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 781 * is used to avoid immediate un-suspend. 782 */ 783 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 784 TDF_ALLPROCSUSP)) == 0) { 785 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 786 thread_lock(td2); 787 goto restart; 788 } 789 if (TD_CAN_ABORT(td2)) { 790 if ((td2->td_flags & TDF_SBDRY) == 0) { 791 thread_suspend_one(td2); 792 td2->td_flags |= TDF_ALLPROCSUSP; 793 } else { 794 wakeup_swapper |= sleepq_abort(td2, ERESTART); 795 return (wakeup_swapper); 796 } 797 } 798 break; 799 default: 800 break; 801 } 802 thread_unlock(td2); 803 return (wakeup_swapper); 804 } 805 806 /* 807 * Enforce single-threading. 808 * 809 * Returns 1 if the caller must abort (another thread is waiting to 810 * exit the process or similar). Process is locked! 811 * Returns 0 when you are successfully the only thread running. 812 * A process has successfully single threaded in the suspend mode when 813 * There are no threads in user mode. Threads in the kernel must be 814 * allowed to continue until they get to the user boundary. They may even 815 * copy out their return values and data before suspending. They may however be 816 * accelerated in reaching the user boundary as we will wake up 817 * any sleeping threads that are interruptable. (PCATCH). 818 */ 819 int 820 thread_single(struct proc *p, int mode) 821 { 822 struct thread *td; 823 struct thread *td2; 824 int remaining, wakeup_swapper; 825 826 td = curthread; 827 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 828 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 829 ("invalid mode %d", mode)); 830 /* 831 * If allowing non-ALLPROC singlethreading for non-curproc 832 * callers, calc_remaining() and remain_for_mode() should be 833 * adjusted to also account for td->td_proc != p. For now 834 * this is not implemented because it is not used. 835 */ 836 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 837 (mode != SINGLE_ALLPROC && td->td_proc == p), 838 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 839 mtx_assert(&Giant, MA_NOTOWNED); 840 PROC_LOCK_ASSERT(p, MA_OWNED); 841 842 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 843 return (0); 844 845 /* Is someone already single threading? */ 846 if (p->p_singlethread != NULL && p->p_singlethread != td) 847 return (1); 848 849 if (mode == SINGLE_EXIT) { 850 p->p_flag |= P_SINGLE_EXIT; 851 p->p_flag &= ~P_SINGLE_BOUNDARY; 852 } else { 853 p->p_flag &= ~P_SINGLE_EXIT; 854 if (mode == SINGLE_BOUNDARY) 855 p->p_flag |= P_SINGLE_BOUNDARY; 856 else 857 p->p_flag &= ~P_SINGLE_BOUNDARY; 858 } 859 if (mode == SINGLE_ALLPROC) 860 p->p_flag |= P_TOTAL_STOP; 861 p->p_flag |= P_STOPPED_SINGLE; 862 PROC_SLOCK(p); 863 p->p_singlethread = td; 864 remaining = calc_remaining(p, mode); 865 while (remaining != remain_for_mode(mode)) { 866 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 867 goto stopme; 868 wakeup_swapper = 0; 869 FOREACH_THREAD_IN_PROC(p, td2) { 870 if (td2 == td) 871 continue; 872 thread_lock(td2); 873 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 874 if (TD_IS_INHIBITED(td2)) { 875 wakeup_swapper |= weed_inhib(mode, td2, p); 876 #ifdef SMP 877 } else if (TD_IS_RUNNING(td2) && td != td2) { 878 forward_signal(td2); 879 thread_unlock(td2); 880 #endif 881 } else 882 thread_unlock(td2); 883 } 884 if (wakeup_swapper) 885 kick_proc0(); 886 remaining = calc_remaining(p, mode); 887 888 /* 889 * Maybe we suspended some threads.. was it enough? 890 */ 891 if (remaining == remain_for_mode(mode)) 892 break; 893 894 stopme: 895 /* 896 * Wake us up when everyone else has suspended. 897 * In the mean time we suspend as well. 898 */ 899 thread_suspend_switch(td, p); 900 remaining = calc_remaining(p, mode); 901 } 902 if (mode == SINGLE_EXIT) { 903 /* 904 * Convert the process to an unthreaded process. The 905 * SINGLE_EXIT is called by exit1() or execve(), in 906 * both cases other threads must be retired. 907 */ 908 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 909 p->p_singlethread = NULL; 910 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 911 912 /* 913 * Wait for any remaining threads to exit cpu_throw(). 914 */ 915 while (p->p_exitthreads != 0) { 916 PROC_SUNLOCK(p); 917 PROC_UNLOCK(p); 918 sched_relinquish(td); 919 PROC_LOCK(p); 920 PROC_SLOCK(p); 921 } 922 } else if (mode == SINGLE_BOUNDARY) { 923 /* 924 * Wait until all suspended threads are removed from 925 * the processors. The thread_suspend_check() 926 * increments p_boundary_count while it is still 927 * running, which makes it possible for the execve() 928 * to destroy vmspace while our other threads are 929 * still using the address space. 930 * 931 * We lock the thread, which is only allowed to 932 * succeed after context switch code finished using 933 * the address space. 934 */ 935 FOREACH_THREAD_IN_PROC(p, td2) { 936 if (td2 == td) 937 continue; 938 thread_lock(td2); 939 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 940 ("td %p not on boundary", td2)); 941 KASSERT(TD_IS_SUSPENDED(td2), 942 ("td %p is not suspended", td2)); 943 thread_unlock(td2); 944 } 945 } 946 PROC_SUNLOCK(p); 947 return (0); 948 } 949 950 bool 951 thread_suspend_check_needed(void) 952 { 953 struct proc *p; 954 struct thread *td; 955 956 td = curthread; 957 p = td->td_proc; 958 PROC_LOCK_ASSERT(p, MA_OWNED); 959 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 960 (td->td_dbgflags & TDB_SUSPEND) != 0)); 961 } 962 963 /* 964 * Called in from locations that can safely check to see 965 * whether we have to suspend or at least throttle for a 966 * single-thread event (e.g. fork). 967 * 968 * Such locations include userret(). 969 * If the "return_instead" argument is non zero, the thread must be able to 970 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 971 * 972 * The 'return_instead' argument tells the function if it may do a 973 * thread_exit() or suspend, or whether the caller must abort and back 974 * out instead. 975 * 976 * If the thread that set the single_threading request has set the 977 * P_SINGLE_EXIT bit in the process flags then this call will never return 978 * if 'return_instead' is false, but will exit. 979 * 980 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 981 *---------------+--------------------+--------------------- 982 * 0 | returns 0 | returns 0 or 1 983 * | when ST ends | immediately 984 *---------------+--------------------+--------------------- 985 * 1 | thread exits | returns 1 986 * | | immediately 987 * 0 = thread_exit() or suspension ok, 988 * other = return error instead of stopping the thread. 989 * 990 * While a full suspension is under effect, even a single threading 991 * thread would be suspended if it made this call (but it shouldn't). 992 * This call should only be made from places where 993 * thread_exit() would be safe as that may be the outcome unless 994 * return_instead is set. 995 */ 996 int 997 thread_suspend_check(int return_instead) 998 { 999 struct thread *td; 1000 struct proc *p; 1001 int wakeup_swapper; 1002 1003 td = curthread; 1004 p = td->td_proc; 1005 mtx_assert(&Giant, MA_NOTOWNED); 1006 PROC_LOCK_ASSERT(p, MA_OWNED); 1007 while (thread_suspend_check_needed()) { 1008 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1009 KASSERT(p->p_singlethread != NULL, 1010 ("singlethread not set")); 1011 /* 1012 * The only suspension in action is a 1013 * single-threading. Single threader need not stop. 1014 * It is safe to access p->p_singlethread unlocked 1015 * because it can only be set to our address by us. 1016 */ 1017 if (p->p_singlethread == td) 1018 return (0); /* Exempt from stopping. */ 1019 } 1020 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 1021 return (EINTR); 1022 1023 /* Should we goto user boundary if we didn't come from there? */ 1024 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1025 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 1026 return (ERESTART); 1027 1028 /* 1029 * Ignore suspend requests if they are deferred. 1030 */ 1031 if ((td->td_flags & TDF_SBDRY) != 0) { 1032 KASSERT(return_instead, 1033 ("TDF_SBDRY set for unsafe thread_suspend_check")); 1034 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 1035 (TDF_SEINTR | TDF_SERESTART), 1036 ("both TDF_SEINTR and TDF_SERESTART")); 1037 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 1038 } 1039 1040 /* 1041 * If the process is waiting for us to exit, 1042 * this thread should just suicide. 1043 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 1044 */ 1045 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 1046 PROC_UNLOCK(p); 1047 1048 /* 1049 * Allow Linux emulation layer to do some work 1050 * before thread suicide. 1051 */ 1052 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 1053 (p->p_sysent->sv_thread_detach)(td); 1054 umtx_thread_exit(td); 1055 kern_thr_exit(td); 1056 panic("stopped thread did not exit"); 1057 } 1058 1059 PROC_SLOCK(p); 1060 thread_stopped(p); 1061 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1062 if (p->p_numthreads == p->p_suspcount + 1) { 1063 thread_lock(p->p_singlethread); 1064 wakeup_swapper = thread_unsuspend_one( 1065 p->p_singlethread, p, false); 1066 if (wakeup_swapper) 1067 kick_proc0(); 1068 } 1069 } 1070 PROC_UNLOCK(p); 1071 thread_lock(td); 1072 /* 1073 * When a thread suspends, it just 1074 * gets taken off all queues. 1075 */ 1076 thread_suspend_one(td); 1077 if (return_instead == 0) { 1078 p->p_boundary_count++; 1079 td->td_flags |= TDF_BOUNDARY; 1080 } 1081 PROC_SUNLOCK(p); 1082 mi_switch(SW_INVOL | SWT_SUSPEND); 1083 PROC_LOCK(p); 1084 } 1085 return (0); 1086 } 1087 1088 /* 1089 * Check for possible stops and suspensions while executing a 1090 * casueword or similar transiently failing operation. 1091 * 1092 * The sleep argument controls whether the function can handle a stop 1093 * request itself or it should return ERESTART and the request is 1094 * proceed at the kernel/user boundary in ast. 1095 * 1096 * Typically, when retrying due to casueword(9) failure (rv == 1), we 1097 * should handle the stop requests there, with exception of cases when 1098 * the thread owns a kernel resource, for instance busied the umtx 1099 * key, or when functions return immediately if thread_check_susp() 1100 * returned non-zero. On the other hand, retrying the whole lock 1101 * operation, we better not stop there but delegate the handling to 1102 * ast. 1103 * 1104 * If the request is for thread termination P_SINGLE_EXIT, we cannot 1105 * handle it at all, and simply return EINTR. 1106 */ 1107 int 1108 thread_check_susp(struct thread *td, bool sleep) 1109 { 1110 struct proc *p; 1111 int error; 1112 1113 /* 1114 * The check for TDF_NEEDSUSPCHK is racy, but it is enough to 1115 * eventually break the lockstep loop. 1116 */ 1117 if ((td->td_flags & TDF_NEEDSUSPCHK) == 0) 1118 return (0); 1119 error = 0; 1120 p = td->td_proc; 1121 PROC_LOCK(p); 1122 if (p->p_flag & P_SINGLE_EXIT) 1123 error = EINTR; 1124 else if (P_SHOULDSTOP(p) || 1125 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) 1126 error = sleep ? thread_suspend_check(0) : ERESTART; 1127 PROC_UNLOCK(p); 1128 return (error); 1129 } 1130 1131 void 1132 thread_suspend_switch(struct thread *td, struct proc *p) 1133 { 1134 1135 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1136 PROC_LOCK_ASSERT(p, MA_OWNED); 1137 PROC_SLOCK_ASSERT(p, MA_OWNED); 1138 /* 1139 * We implement thread_suspend_one in stages here to avoid 1140 * dropping the proc lock while the thread lock is owned. 1141 */ 1142 if (p == td->td_proc) { 1143 thread_stopped(p); 1144 p->p_suspcount++; 1145 } 1146 PROC_UNLOCK(p); 1147 thread_lock(td); 1148 td->td_flags &= ~TDF_NEEDSUSPCHK; 1149 TD_SET_SUSPENDED(td); 1150 sched_sleep(td, 0); 1151 PROC_SUNLOCK(p); 1152 DROP_GIANT(); 1153 mi_switch(SW_VOL | SWT_SUSPEND); 1154 PICKUP_GIANT(); 1155 PROC_LOCK(p); 1156 PROC_SLOCK(p); 1157 } 1158 1159 void 1160 thread_suspend_one(struct thread *td) 1161 { 1162 struct proc *p; 1163 1164 p = td->td_proc; 1165 PROC_SLOCK_ASSERT(p, MA_OWNED); 1166 THREAD_LOCK_ASSERT(td, MA_OWNED); 1167 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1168 p->p_suspcount++; 1169 td->td_flags &= ~TDF_NEEDSUSPCHK; 1170 TD_SET_SUSPENDED(td); 1171 sched_sleep(td, 0); 1172 } 1173 1174 static int 1175 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1176 { 1177 1178 THREAD_LOCK_ASSERT(td, MA_OWNED); 1179 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1180 TD_CLR_SUSPENDED(td); 1181 td->td_flags &= ~TDF_ALLPROCSUSP; 1182 if (td->td_proc == p) { 1183 PROC_SLOCK_ASSERT(p, MA_OWNED); 1184 p->p_suspcount--; 1185 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1186 td->td_flags &= ~TDF_BOUNDARY; 1187 p->p_boundary_count--; 1188 } 1189 } 1190 return (setrunnable(td, 0)); 1191 } 1192 1193 /* 1194 * Allow all threads blocked by single threading to continue running. 1195 */ 1196 void 1197 thread_unsuspend(struct proc *p) 1198 { 1199 struct thread *td; 1200 int wakeup_swapper; 1201 1202 PROC_LOCK_ASSERT(p, MA_OWNED); 1203 PROC_SLOCK_ASSERT(p, MA_OWNED); 1204 wakeup_swapper = 0; 1205 if (!P_SHOULDSTOP(p)) { 1206 FOREACH_THREAD_IN_PROC(p, td) { 1207 thread_lock(td); 1208 if (TD_IS_SUSPENDED(td)) { 1209 wakeup_swapper |= thread_unsuspend_one(td, p, 1210 true); 1211 } else 1212 thread_unlock(td); 1213 } 1214 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1215 p->p_numthreads == p->p_suspcount) { 1216 /* 1217 * Stopping everything also did the job for the single 1218 * threading request. Now we've downgraded to single-threaded, 1219 * let it continue. 1220 */ 1221 if (p->p_singlethread->td_proc == p) { 1222 thread_lock(p->p_singlethread); 1223 wakeup_swapper = thread_unsuspend_one( 1224 p->p_singlethread, p, false); 1225 } 1226 } 1227 if (wakeup_swapper) 1228 kick_proc0(); 1229 } 1230 1231 /* 1232 * End the single threading mode.. 1233 */ 1234 void 1235 thread_single_end(struct proc *p, int mode) 1236 { 1237 struct thread *td; 1238 int wakeup_swapper; 1239 1240 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1241 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1242 ("invalid mode %d", mode)); 1243 PROC_LOCK_ASSERT(p, MA_OWNED); 1244 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1245 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1246 ("mode %d does not match P_TOTAL_STOP", mode)); 1247 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1248 ("thread_single_end from other thread %p %p", 1249 curthread, p->p_singlethread)); 1250 KASSERT(mode != SINGLE_BOUNDARY || 1251 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1252 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1253 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1254 P_TOTAL_STOP); 1255 PROC_SLOCK(p); 1256 p->p_singlethread = NULL; 1257 wakeup_swapper = 0; 1258 /* 1259 * If there are other threads they may now run, 1260 * unless of course there is a blanket 'stop order' 1261 * on the process. The single threader must be allowed 1262 * to continue however as this is a bad place to stop. 1263 */ 1264 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1265 FOREACH_THREAD_IN_PROC(p, td) { 1266 thread_lock(td); 1267 if (TD_IS_SUSPENDED(td)) { 1268 wakeup_swapper |= thread_unsuspend_one(td, p, 1269 mode == SINGLE_BOUNDARY); 1270 } else 1271 thread_unlock(td); 1272 } 1273 } 1274 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1275 ("inconsistent boundary count %d", p->p_boundary_count)); 1276 PROC_SUNLOCK(p); 1277 if (wakeup_swapper) 1278 kick_proc0(); 1279 } 1280 1281 struct thread * 1282 thread_find(struct proc *p, lwpid_t tid) 1283 { 1284 struct thread *td; 1285 1286 PROC_LOCK_ASSERT(p, MA_OWNED); 1287 FOREACH_THREAD_IN_PROC(p, td) { 1288 if (td->td_tid == tid) 1289 break; 1290 } 1291 return (td); 1292 } 1293 1294 /* Locate a thread by number; return with proc lock held. */ 1295 struct thread * 1296 tdfind(lwpid_t tid, pid_t pid) 1297 { 1298 #define RUN_THRESH 16 1299 struct thread *td; 1300 int run = 0; 1301 1302 td = curthread; 1303 if (td->td_tid == tid) { 1304 if (pid != -1 && td->td_proc->p_pid != pid) 1305 return (NULL); 1306 PROC_LOCK(td->td_proc); 1307 return (td); 1308 } 1309 1310 rw_rlock(&tidhash_lock); 1311 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1312 if (td->td_tid == tid) { 1313 if (pid != -1 && td->td_proc->p_pid != pid) { 1314 td = NULL; 1315 break; 1316 } 1317 PROC_LOCK(td->td_proc); 1318 if (td->td_proc->p_state == PRS_NEW) { 1319 PROC_UNLOCK(td->td_proc); 1320 td = NULL; 1321 break; 1322 } 1323 if (run > RUN_THRESH) { 1324 if (rw_try_upgrade(&tidhash_lock)) { 1325 LIST_REMOVE(td, td_hash); 1326 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1327 td, td_hash); 1328 rw_wunlock(&tidhash_lock); 1329 return (td); 1330 } 1331 } 1332 break; 1333 } 1334 run++; 1335 } 1336 rw_runlock(&tidhash_lock); 1337 return (td); 1338 } 1339 1340 void 1341 tidhash_add(struct thread *td) 1342 { 1343 rw_wlock(&tidhash_lock); 1344 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1345 rw_wunlock(&tidhash_lock); 1346 } 1347 1348 void 1349 tidhash_remove(struct thread *td) 1350 { 1351 rw_wlock(&tidhash_lock); 1352 LIST_REMOVE(td, td_hash); 1353 rw_wunlock(&tidhash_lock); 1354 } 1355