kern_thread.c revision 275617
1/*- 2 * Copyright (C) 2001 Julian Elischer <julian@freebsd.org>. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice(s), this list of conditions and the following disclaimer as 10 * the first lines of this file unmodified other than the possible 11 * addition of one or more copyright notices. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice(s), this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 19 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 23 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 26 * DAMAGE. 27 */ 28 29#include "opt_witness.h" 30#include "opt_hwpmc_hooks.h" 31 32#include <sys/cdefs.h> 33__FBSDID("$FreeBSD: head/sys/kern/kern_thread.c 275617 2014-12-08 16:27:43Z kib $"); 34 35#include <sys/param.h> 36#include <sys/systm.h> 37#include <sys/kernel.h> 38#include <sys/lock.h> 39#include <sys/mutex.h> 40#include <sys/proc.h> 41#include <sys/rangelock.h> 42#include <sys/resourcevar.h> 43#include <sys/sdt.h> 44#include <sys/smp.h> 45#include <sys/sched.h> 46#include <sys/sleepqueue.h> 47#include <sys/selinfo.h> 48#include <sys/turnstile.h> 49#include <sys/ktr.h> 50#include <sys/rwlock.h> 51#include <sys/umtx.h> 52#include <sys/cpuset.h> 53#ifdef HWPMC_HOOKS 54#include <sys/pmckern.h> 55#endif 56 57#include <security/audit/audit.h> 58 59#include <vm/vm.h> 60#include <vm/vm_extern.h> 61#include <vm/uma.h> 62#include <sys/eventhandler.h> 63 64SDT_PROVIDER_DECLARE(proc); 65SDT_PROBE_DEFINE(proc, , , lwp__exit); 66 67/* 68 * thread related storage. 69 */ 70static uma_zone_t thread_zone; 71 72TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 73static struct mtx zombie_lock; 74MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 75 76static void thread_zombie(struct thread *); 77 78#define TID_BUFFER_SIZE 1024 79 80struct mtx tid_lock; 81static struct unrhdr *tid_unrhdr; 82static lwpid_t tid_buffer[TID_BUFFER_SIZE]; 83static int tid_head, tid_tail; 84static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 85 86struct tidhashhead *tidhashtbl; 87u_long tidhash; 88struct rwlock tidhash_lock; 89 90static lwpid_t 91tid_alloc(void) 92{ 93 lwpid_t tid; 94 95 tid = alloc_unr(tid_unrhdr); 96 if (tid != -1) 97 return (tid); 98 mtx_lock(&tid_lock); 99 if (tid_head == tid_tail) { 100 mtx_unlock(&tid_lock); 101 return (-1); 102 } 103 tid = tid_buffer[tid_head]; 104 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 105 mtx_unlock(&tid_lock); 106 return (tid); 107} 108 109static void 110tid_free(lwpid_t tid) 111{ 112 lwpid_t tmp_tid = -1; 113 114 mtx_lock(&tid_lock); 115 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { 116 tmp_tid = tid_buffer[tid_head]; 117 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 118 } 119 tid_buffer[tid_tail] = tid; 120 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE; 121 mtx_unlock(&tid_lock); 122 if (tmp_tid != -1) 123 free_unr(tid_unrhdr, tmp_tid); 124} 125 126/* 127 * Prepare a thread for use. 128 */ 129static int 130thread_ctor(void *mem, int size, void *arg, int flags) 131{ 132 struct thread *td; 133 134 td = (struct thread *)mem; 135 td->td_state = TDS_INACTIVE; 136 td->td_oncpu = NOCPU; 137 138 td->td_tid = tid_alloc(); 139 140 /* 141 * Note that td_critnest begins life as 1 because the thread is not 142 * running and is thereby implicitly waiting to be on the receiving 143 * end of a context switch. 144 */ 145 td->td_critnest = 1; 146 td->td_lend_user_pri = PRI_MAX; 147 EVENTHANDLER_INVOKE(thread_ctor, td); 148#ifdef AUDIT 149 audit_thread_alloc(td); 150#endif 151 umtx_thread_alloc(td); 152 return (0); 153} 154 155/* 156 * Reclaim a thread after use. 157 */ 158static void 159thread_dtor(void *mem, int size, void *arg) 160{ 161 struct thread *td; 162 163 td = (struct thread *)mem; 164 165#ifdef INVARIANTS 166 /* Verify that this thread is in a safe state to free. */ 167 switch (td->td_state) { 168 case TDS_INHIBITED: 169 case TDS_RUNNING: 170 case TDS_CAN_RUN: 171 case TDS_RUNQ: 172 /* 173 * We must never unlink a thread that is in one of 174 * these states, because it is currently active. 175 */ 176 panic("bad state for thread unlinking"); 177 /* NOTREACHED */ 178 case TDS_INACTIVE: 179 break; 180 default: 181 panic("bad thread state"); 182 /* NOTREACHED */ 183 } 184#endif 185#ifdef AUDIT 186 audit_thread_free(td); 187#endif 188 /* Free all OSD associated to this thread. */ 189 osd_thread_exit(td); 190 191 EVENTHANDLER_INVOKE(thread_dtor, td); 192 tid_free(td->td_tid); 193} 194 195/* 196 * Initialize type-stable parts of a thread (when newly created). 197 */ 198static int 199thread_init(void *mem, int size, int flags) 200{ 201 struct thread *td; 202 203 td = (struct thread *)mem; 204 205 td->td_sleepqueue = sleepq_alloc(); 206 td->td_turnstile = turnstile_alloc(); 207 td->td_rlqe = NULL; 208 EVENTHANDLER_INVOKE(thread_init, td); 209 td->td_sched = (struct td_sched *)&td[1]; 210 umtx_thread_init(td); 211 td->td_kstack = 0; 212 return (0); 213} 214 215/* 216 * Tear down type-stable parts of a thread (just before being discarded). 217 */ 218static void 219thread_fini(void *mem, int size) 220{ 221 struct thread *td; 222 223 td = (struct thread *)mem; 224 EVENTHANDLER_INVOKE(thread_fini, td); 225 rlqentry_free(td->td_rlqe); 226 turnstile_free(td->td_turnstile); 227 sleepq_free(td->td_sleepqueue); 228 umtx_thread_fini(td); 229 seltdfini(td); 230} 231 232/* 233 * For a newly created process, 234 * link up all the structures and its initial threads etc. 235 * called from: 236 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 237 * proc_dtor() (should go away) 238 * proc_init() 239 */ 240void 241proc_linkup0(struct proc *p, struct thread *td) 242{ 243 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 244 proc_linkup(p, td); 245} 246 247void 248proc_linkup(struct proc *p, struct thread *td) 249{ 250 251 sigqueue_init(&p->p_sigqueue, p); 252 p->p_ksi = ksiginfo_alloc(1); 253 if (p->p_ksi != NULL) { 254 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 255 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 256 } 257 LIST_INIT(&p->p_mqnotifier); 258 p->p_numthreads = 0; 259 thread_link(td, p); 260} 261 262/* 263 * Initialize global thread allocation resources. 264 */ 265void 266threadinit(void) 267{ 268 269 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 270 271 /* 272 * pid_max cannot be greater than PID_MAX. 273 * leave one number for thread0. 274 */ 275 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 276 277 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 278 thread_ctor, thread_dtor, thread_init, thread_fini, 279 16 - 1, 0); 280 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 281 rw_init(&tidhash_lock, "tidhash"); 282} 283 284/* 285 * Place an unused thread on the zombie list. 286 * Use the slpq as that must be unused by now. 287 */ 288void 289thread_zombie(struct thread *td) 290{ 291 mtx_lock_spin(&zombie_lock); 292 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 293 mtx_unlock_spin(&zombie_lock); 294} 295 296/* 297 * Release a thread that has exited after cpu_throw(). 298 */ 299void 300thread_stash(struct thread *td) 301{ 302 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 303 thread_zombie(td); 304} 305 306/* 307 * Reap zombie resources. 308 */ 309void 310thread_reap(void) 311{ 312 struct thread *td_first, *td_next; 313 314 /* 315 * Don't even bother to lock if none at this instant, 316 * we really don't care about the next instant.. 317 */ 318 if (!TAILQ_EMPTY(&zombie_threads)) { 319 mtx_lock_spin(&zombie_lock); 320 td_first = TAILQ_FIRST(&zombie_threads); 321 if (td_first) 322 TAILQ_INIT(&zombie_threads); 323 mtx_unlock_spin(&zombie_lock); 324 while (td_first) { 325 td_next = TAILQ_NEXT(td_first, td_slpq); 326 if (td_first->td_ucred) 327 crfree(td_first->td_ucred); 328 thread_free(td_first); 329 td_first = td_next; 330 } 331 } 332} 333 334/* 335 * Allocate a thread. 336 */ 337struct thread * 338thread_alloc(int pages) 339{ 340 struct thread *td; 341 342 thread_reap(); /* check if any zombies to get */ 343 344 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 345 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 346 if (!vm_thread_new(td, pages)) { 347 uma_zfree(thread_zone, td); 348 return (NULL); 349 } 350 cpu_thread_alloc(td); 351 return (td); 352} 353 354int 355thread_alloc_stack(struct thread *td, int pages) 356{ 357 358 KASSERT(td->td_kstack == 0, 359 ("thread_alloc_stack called on a thread with kstack")); 360 if (!vm_thread_new(td, pages)) 361 return (0); 362 cpu_thread_alloc(td); 363 return (1); 364} 365 366/* 367 * Deallocate a thread. 368 */ 369void 370thread_free(struct thread *td) 371{ 372 373 lock_profile_thread_exit(td); 374 if (td->td_cpuset) 375 cpuset_rel(td->td_cpuset); 376 td->td_cpuset = NULL; 377 cpu_thread_free(td); 378 if (td->td_kstack != 0) 379 vm_thread_dispose(td); 380 uma_zfree(thread_zone, td); 381} 382 383/* 384 * Discard the current thread and exit from its context. 385 * Always called with scheduler locked. 386 * 387 * Because we can't free a thread while we're operating under its context, 388 * push the current thread into our CPU's deadthread holder. This means 389 * we needn't worry about someone else grabbing our context before we 390 * do a cpu_throw(). 391 */ 392void 393thread_exit(void) 394{ 395 uint64_t runtime, new_switchtime; 396 struct thread *td; 397 struct thread *td2; 398 struct proc *p; 399 int wakeup_swapper; 400 401 td = curthread; 402 p = td->td_proc; 403 404 PROC_SLOCK_ASSERT(p, MA_OWNED); 405 mtx_assert(&Giant, MA_NOTOWNED); 406 407 PROC_LOCK_ASSERT(p, MA_OWNED); 408 KASSERT(p != NULL, ("thread exiting without a process")); 409 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 410 (long)p->p_pid, td->td_name); 411 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 412 413#ifdef AUDIT 414 AUDIT_SYSCALL_EXIT(0, td); 415#endif 416 umtx_thread_exit(td); 417 /* 418 * drop FPU & debug register state storage, or any other 419 * architecture specific resources that 420 * would not be on a new untouched process. 421 */ 422 cpu_thread_exit(td); /* XXXSMP */ 423 424 /* 425 * The last thread is left attached to the process 426 * So that the whole bundle gets recycled. Skip 427 * all this stuff if we never had threads. 428 * EXIT clears all sign of other threads when 429 * it goes to single threading, so the last thread always 430 * takes the short path. 431 */ 432 if (p->p_flag & P_HADTHREADS) { 433 if (p->p_numthreads > 1) { 434 atomic_add_int(&td->td_proc->p_exitthreads, 1); 435 thread_unlink(td); 436 td2 = FIRST_THREAD_IN_PROC(p); 437 sched_exit_thread(td2, td); 438 439 /* 440 * The test below is NOT true if we are the 441 * sole exiting thread. P_STOPPED_SINGLE is unset 442 * in exit1() after it is the only survivor. 443 */ 444 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 445 if (p->p_numthreads == p->p_suspcount) { 446 thread_lock(p->p_singlethread); 447 wakeup_swapper = thread_unsuspend_one( 448 p->p_singlethread); 449 thread_unlock(p->p_singlethread); 450 if (wakeup_swapper) 451 kick_proc0(); 452 } 453 } 454 455 PCPU_SET(deadthread, td); 456 } else { 457 /* 458 * The last thread is exiting.. but not through exit() 459 */ 460 panic ("thread_exit: Last thread exiting on its own"); 461 } 462 } 463#ifdef HWPMC_HOOKS 464 /* 465 * If this thread is part of a process that is being tracked by hwpmc(4), 466 * inform the module of the thread's impending exit. 467 */ 468 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 469 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 470#endif 471 PROC_UNLOCK(p); 472 PROC_STATLOCK(p); 473 thread_lock(td); 474 PROC_SUNLOCK(p); 475 476 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 477 new_switchtime = cpu_ticks(); 478 runtime = new_switchtime - PCPU_GET(switchtime); 479 td->td_runtime += runtime; 480 td->td_incruntime += runtime; 481 PCPU_SET(switchtime, new_switchtime); 482 PCPU_SET(switchticks, ticks); 483 PCPU_INC(cnt.v_swtch); 484 485 /* Save our resource usage in our process. */ 486 td->td_ru.ru_nvcsw++; 487 ruxagg(p, td); 488 rucollect(&p->p_ru, &td->td_ru); 489 PROC_STATUNLOCK(p); 490 491 td->td_state = TDS_INACTIVE; 492#ifdef WITNESS 493 witness_thread_exit(td); 494#endif 495 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 496 sched_throw(td); 497 panic("I'm a teapot!"); 498 /* NOTREACHED */ 499} 500 501/* 502 * Do any thread specific cleanups that may be needed in wait() 503 * called with Giant, proc and schedlock not held. 504 */ 505void 506thread_wait(struct proc *p) 507{ 508 struct thread *td; 509 510 mtx_assert(&Giant, MA_NOTOWNED); 511 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 512 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 513 td = FIRST_THREAD_IN_PROC(p); 514 /* Lock the last thread so we spin until it exits cpu_throw(). */ 515 thread_lock(td); 516 thread_unlock(td); 517 lock_profile_thread_exit(td); 518 cpuset_rel(td->td_cpuset); 519 td->td_cpuset = NULL; 520 cpu_thread_clean(td); 521 crfree(td->td_ucred); 522 thread_reap(); /* check for zombie threads etc. */ 523} 524 525/* 526 * Link a thread to a process. 527 * set up anything that needs to be initialized for it to 528 * be used by the process. 529 */ 530void 531thread_link(struct thread *td, struct proc *p) 532{ 533 534 /* 535 * XXX This can't be enabled because it's called for proc0 before 536 * its lock has been created. 537 * PROC_LOCK_ASSERT(p, MA_OWNED); 538 */ 539 td->td_state = TDS_INACTIVE; 540 td->td_proc = p; 541 td->td_flags = TDF_INMEM; 542 543 LIST_INIT(&td->td_contested); 544 LIST_INIT(&td->td_lprof[0]); 545 LIST_INIT(&td->td_lprof[1]); 546 sigqueue_init(&td->td_sigqueue, p); 547 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 548 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 549 p->p_numthreads++; 550} 551 552/* 553 * Called from: 554 * thread_exit() 555 */ 556void 557thread_unlink(struct thread *td) 558{ 559 struct proc *p = td->td_proc; 560 561 PROC_LOCK_ASSERT(p, MA_OWNED); 562 TAILQ_REMOVE(&p->p_threads, td, td_plist); 563 p->p_numthreads--; 564 /* could clear a few other things here */ 565 /* Must NOT clear links to proc! */ 566} 567 568static int 569calc_remaining(struct proc *p, int mode) 570{ 571 int remaining; 572 573 PROC_LOCK_ASSERT(p, MA_OWNED); 574 PROC_SLOCK_ASSERT(p, MA_OWNED); 575 if (mode == SINGLE_EXIT) 576 remaining = p->p_numthreads; 577 else if (mode == SINGLE_BOUNDARY) 578 remaining = p->p_numthreads - p->p_boundary_count; 579 else if (mode == SINGLE_NO_EXIT) 580 remaining = p->p_numthreads - p->p_suspcount; 581 else 582 panic("calc_remaining: wrong mode %d", mode); 583 return (remaining); 584} 585 586static int 587remain_for_mode(int mode) 588{ 589 590 return (1); 591} 592 593static int 594weed_inhib(int mode, struct thread *td2, struct proc *p) 595{ 596 int wakeup_swapper; 597 598 PROC_LOCK_ASSERT(p, MA_OWNED); 599 PROC_SLOCK_ASSERT(p, MA_OWNED); 600 THREAD_LOCK_ASSERT(td2, MA_OWNED); 601 602 wakeup_swapper = 0; 603 switch (mode) { 604 case SINGLE_EXIT: 605 if (TD_IS_SUSPENDED(td2)) 606 wakeup_swapper |= thread_unsuspend_one(td2); 607 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 608 wakeup_swapper |= sleepq_abort(td2, EINTR); 609 break; 610 case SINGLE_BOUNDARY: 611 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 612 wakeup_swapper |= thread_unsuspend_one(td2); 613 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 614 wakeup_swapper |= sleepq_abort(td2, ERESTART); 615 break; 616 case SINGLE_NO_EXIT: 617 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 618 wakeup_swapper |= thread_unsuspend_one(td2); 619 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 620 wakeup_swapper |= sleepq_abort(td2, ERESTART); 621 break; 622 } 623 return (wakeup_swapper); 624} 625 626/* 627 * Enforce single-threading. 628 * 629 * Returns 1 if the caller must abort (another thread is waiting to 630 * exit the process or similar). Process is locked! 631 * Returns 0 when you are successfully the only thread running. 632 * A process has successfully single threaded in the suspend mode when 633 * There are no threads in user mode. Threads in the kernel must be 634 * allowed to continue until they get to the user boundary. They may even 635 * copy out their return values and data before suspending. They may however be 636 * accelerated in reaching the user boundary as we will wake up 637 * any sleeping threads that are interruptable. (PCATCH). 638 */ 639int 640thread_single(int mode) 641{ 642 struct thread *td; 643 struct thread *td2; 644 struct proc *p; 645 int remaining, wakeup_swapper; 646 647 td = curthread; 648 p = td->td_proc; 649 mtx_assert(&Giant, MA_NOTOWNED); 650 PROC_LOCK_ASSERT(p, MA_OWNED); 651 652 if ((p->p_flag & P_HADTHREADS) == 0) 653 return (0); 654 655 /* Is someone already single threading? */ 656 if (p->p_singlethread != NULL && p->p_singlethread != td) 657 return (1); 658 659 if (mode == SINGLE_EXIT) { 660 p->p_flag |= P_SINGLE_EXIT; 661 p->p_flag &= ~P_SINGLE_BOUNDARY; 662 } else { 663 p->p_flag &= ~P_SINGLE_EXIT; 664 if (mode == SINGLE_BOUNDARY) 665 p->p_flag |= P_SINGLE_BOUNDARY; 666 else 667 p->p_flag &= ~P_SINGLE_BOUNDARY; 668 } 669 p->p_flag |= P_STOPPED_SINGLE; 670 PROC_SLOCK(p); 671 p->p_singlethread = td; 672 remaining = calc_remaining(p, mode); 673 while (remaining != remain_for_mode(mode)) { 674 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 675 goto stopme; 676 wakeup_swapper = 0; 677 FOREACH_THREAD_IN_PROC(p, td2) { 678 if (td2 == td) 679 continue; 680 thread_lock(td2); 681 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 682 if (TD_IS_INHIBITED(td2)) 683 wakeup_swapper |= weed_inhib(mode, td2, p); 684#ifdef SMP 685 else if (TD_IS_RUNNING(td2) && td != td2) { 686 forward_signal(td2); 687 } 688#endif 689 thread_unlock(td2); 690 } 691 if (wakeup_swapper) 692 kick_proc0(); 693 remaining = calc_remaining(p, mode); 694 695 /* 696 * Maybe we suspended some threads.. was it enough? 697 */ 698 if (remaining == remain_for_mode(mode)) 699 break; 700 701stopme: 702 /* 703 * Wake us up when everyone else has suspended. 704 * In the mean time we suspend as well. 705 */ 706 thread_suspend_switch(td); 707 remaining = calc_remaining(p, mode); 708 } 709 if (mode == SINGLE_EXIT) { 710 /* 711 * Convert the process to an unthreaded process. The 712 * SINGLE_EXIT is called by exit1() or execve(), in 713 * both cases other threads must be retired. 714 */ 715 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 716 p->p_singlethread = NULL; 717 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 718 719 /* 720 * Wait for any remaining threads to exit cpu_throw(). 721 */ 722 while (p->p_exitthreads != 0) { 723 PROC_SUNLOCK(p); 724 PROC_UNLOCK(p); 725 sched_relinquish(td); 726 PROC_LOCK(p); 727 PROC_SLOCK(p); 728 } 729 } 730 PROC_SUNLOCK(p); 731 return (0); 732} 733 734bool 735thread_suspend_check_needed(void) 736{ 737 struct proc *p; 738 struct thread *td; 739 740 td = curthread; 741 p = td->td_proc; 742 PROC_LOCK_ASSERT(p, MA_OWNED); 743 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 744 (td->td_dbgflags & TDB_SUSPEND) != 0)); 745} 746 747/* 748 * Called in from locations that can safely check to see 749 * whether we have to suspend or at least throttle for a 750 * single-thread event (e.g. fork). 751 * 752 * Such locations include userret(). 753 * If the "return_instead" argument is non zero, the thread must be able to 754 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 755 * 756 * The 'return_instead' argument tells the function if it may do a 757 * thread_exit() or suspend, or whether the caller must abort and back 758 * out instead. 759 * 760 * If the thread that set the single_threading request has set the 761 * P_SINGLE_EXIT bit in the process flags then this call will never return 762 * if 'return_instead' is false, but will exit. 763 * 764 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 765 *---------------+--------------------+--------------------- 766 * 0 | returns 0 | returns 0 or 1 767 * | when ST ends | immediately 768 *---------------+--------------------+--------------------- 769 * 1 | thread exits | returns 1 770 * | | immediately 771 * 0 = thread_exit() or suspension ok, 772 * other = return error instead of stopping the thread. 773 * 774 * While a full suspension is under effect, even a single threading 775 * thread would be suspended if it made this call (but it shouldn't). 776 * This call should only be made from places where 777 * thread_exit() would be safe as that may be the outcome unless 778 * return_instead is set. 779 */ 780int 781thread_suspend_check(int return_instead) 782{ 783 struct thread *td; 784 struct proc *p; 785 int wakeup_swapper; 786 787 td = curthread; 788 p = td->td_proc; 789 mtx_assert(&Giant, MA_NOTOWNED); 790 PROC_LOCK_ASSERT(p, MA_OWNED); 791 while (thread_suspend_check_needed()) { 792 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 793 KASSERT(p->p_singlethread != NULL, 794 ("singlethread not set")); 795 /* 796 * The only suspension in action is a 797 * single-threading. Single threader need not stop. 798 * XXX Should be safe to access unlocked 799 * as it can only be set to be true by us. 800 */ 801 if (p->p_singlethread == td) 802 return (0); /* Exempt from stopping. */ 803 } 804 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 805 return (EINTR); 806 807 /* Should we goto user boundary if we didn't come from there? */ 808 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 809 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 810 return (ERESTART); 811 812 /* 813 * Ignore suspend requests for stop signals if they 814 * are deferred. 815 */ 816 if (P_SHOULDSTOP(p) == P_STOPPED_SIG && 817 td->td_flags & TDF_SBDRY) { 818 KASSERT(return_instead, 819 ("TDF_SBDRY set for unsafe thread_suspend_check")); 820 return (0); 821 } 822 823 /* 824 * If the process is waiting for us to exit, 825 * this thread should just suicide. 826 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 827 */ 828 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 829 PROC_UNLOCK(p); 830 tidhash_remove(td); 831 PROC_LOCK(p); 832 tdsigcleanup(td); 833 PROC_SLOCK(p); 834 thread_stopped(p); 835 thread_exit(); 836 } 837 838 PROC_SLOCK(p); 839 thread_stopped(p); 840 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 841 if (p->p_numthreads == p->p_suspcount + 1) { 842 thread_lock(p->p_singlethread); 843 wakeup_swapper = 844 thread_unsuspend_one(p->p_singlethread); 845 thread_unlock(p->p_singlethread); 846 if (wakeup_swapper) 847 kick_proc0(); 848 } 849 } 850 PROC_UNLOCK(p); 851 thread_lock(td); 852 /* 853 * When a thread suspends, it just 854 * gets taken off all queues. 855 */ 856 thread_suspend_one(td); 857 if (return_instead == 0) { 858 p->p_boundary_count++; 859 td->td_flags |= TDF_BOUNDARY; 860 } 861 PROC_SUNLOCK(p); 862 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 863 if (return_instead == 0) 864 td->td_flags &= ~TDF_BOUNDARY; 865 thread_unlock(td); 866 PROC_LOCK(p); 867 if (return_instead == 0) { 868 PROC_SLOCK(p); 869 p->p_boundary_count--; 870 PROC_SUNLOCK(p); 871 } 872 } 873 return (0); 874} 875 876void 877thread_suspend_switch(struct thread *td) 878{ 879 struct proc *p; 880 881 p = td->td_proc; 882 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 883 PROC_LOCK_ASSERT(p, MA_OWNED); 884 PROC_SLOCK_ASSERT(p, MA_OWNED); 885 /* 886 * We implement thread_suspend_one in stages here to avoid 887 * dropping the proc lock while the thread lock is owned. 888 */ 889 thread_stopped(p); 890 p->p_suspcount++; 891 PROC_UNLOCK(p); 892 thread_lock(td); 893 td->td_flags &= ~TDF_NEEDSUSPCHK; 894 TD_SET_SUSPENDED(td); 895 sched_sleep(td, 0); 896 PROC_SUNLOCK(p); 897 DROP_GIANT(); 898 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 899 thread_unlock(td); 900 PICKUP_GIANT(); 901 PROC_LOCK(p); 902 PROC_SLOCK(p); 903} 904 905void 906thread_suspend_one(struct thread *td) 907{ 908 struct proc *p = td->td_proc; 909 910 PROC_SLOCK_ASSERT(p, MA_OWNED); 911 THREAD_LOCK_ASSERT(td, MA_OWNED); 912 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 913 p->p_suspcount++; 914 td->td_flags &= ~TDF_NEEDSUSPCHK; 915 TD_SET_SUSPENDED(td); 916 sched_sleep(td, 0); 917} 918 919int 920thread_unsuspend_one(struct thread *td) 921{ 922 struct proc *p = td->td_proc; 923 924 PROC_SLOCK_ASSERT(p, MA_OWNED); 925 THREAD_LOCK_ASSERT(td, MA_OWNED); 926 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 927 TD_CLR_SUSPENDED(td); 928 p->p_suspcount--; 929 return (setrunnable(td)); 930} 931 932/* 933 * Allow all threads blocked by single threading to continue running. 934 */ 935void 936thread_unsuspend(struct proc *p) 937{ 938 struct thread *td; 939 int wakeup_swapper; 940 941 PROC_LOCK_ASSERT(p, MA_OWNED); 942 PROC_SLOCK_ASSERT(p, MA_OWNED); 943 wakeup_swapper = 0; 944 if (!P_SHOULDSTOP(p)) { 945 FOREACH_THREAD_IN_PROC(p, td) { 946 thread_lock(td); 947 if (TD_IS_SUSPENDED(td)) { 948 wakeup_swapper |= thread_unsuspend_one(td); 949 } 950 thread_unlock(td); 951 } 952 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 953 (p->p_numthreads == p->p_suspcount)) { 954 /* 955 * Stopping everything also did the job for the single 956 * threading request. Now we've downgraded to single-threaded, 957 * let it continue. 958 */ 959 thread_lock(p->p_singlethread); 960 wakeup_swapper = thread_unsuspend_one(p->p_singlethread); 961 thread_unlock(p->p_singlethread); 962 } 963 if (wakeup_swapper) 964 kick_proc0(); 965} 966 967/* 968 * End the single threading mode.. 969 */ 970void 971thread_single_end(void) 972{ 973 struct thread *td; 974 struct proc *p; 975 int wakeup_swapper; 976 977 p = curproc; 978 PROC_LOCK_ASSERT(p, MA_OWNED); 979 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 980 PROC_SLOCK(p); 981 p->p_singlethread = NULL; 982 wakeup_swapper = 0; 983 /* 984 * If there are other threads they may now run, 985 * unless of course there is a blanket 'stop order' 986 * on the process. The single threader must be allowed 987 * to continue however as this is a bad place to stop. 988 */ 989 if (p->p_numthreads != remain_for_mode(SINGLE_EXIT) && 990 !P_SHOULDSTOP(p)) { 991 FOREACH_THREAD_IN_PROC(p, td) { 992 thread_lock(td); 993 if (TD_IS_SUSPENDED(td)) { 994 wakeup_swapper |= thread_unsuspend_one(td); 995 } 996 thread_unlock(td); 997 } 998 } 999 PROC_SUNLOCK(p); 1000 if (wakeup_swapper) 1001 kick_proc0(); 1002} 1003 1004struct thread * 1005thread_find(struct proc *p, lwpid_t tid) 1006{ 1007 struct thread *td; 1008 1009 PROC_LOCK_ASSERT(p, MA_OWNED); 1010 FOREACH_THREAD_IN_PROC(p, td) { 1011 if (td->td_tid == tid) 1012 break; 1013 } 1014 return (td); 1015} 1016 1017/* Locate a thread by number; return with proc lock held. */ 1018struct thread * 1019tdfind(lwpid_t tid, pid_t pid) 1020{ 1021#define RUN_THRESH 16 1022 struct thread *td; 1023 int run = 0; 1024 1025 rw_rlock(&tidhash_lock); 1026 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1027 if (td->td_tid == tid) { 1028 if (pid != -1 && td->td_proc->p_pid != pid) { 1029 td = NULL; 1030 break; 1031 } 1032 PROC_LOCK(td->td_proc); 1033 if (td->td_proc->p_state == PRS_NEW) { 1034 PROC_UNLOCK(td->td_proc); 1035 td = NULL; 1036 break; 1037 } 1038 if (run > RUN_THRESH) { 1039 if (rw_try_upgrade(&tidhash_lock)) { 1040 LIST_REMOVE(td, td_hash); 1041 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1042 td, td_hash); 1043 rw_wunlock(&tidhash_lock); 1044 return (td); 1045 } 1046 } 1047 break; 1048 } 1049 run++; 1050 } 1051 rw_runlock(&tidhash_lock); 1052 return (td); 1053} 1054 1055void 1056tidhash_add(struct thread *td) 1057{ 1058 rw_wlock(&tidhash_lock); 1059 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1060 rw_wunlock(&tidhash_lock); 1061} 1062 1063void 1064tidhash_remove(struct thread *td) 1065{ 1066 rw_wlock(&tidhash_lock); 1067 LIST_REMOVE(td, td_hash); 1068 rw_wunlock(&tidhash_lock); 1069} 1070