kern_thread.c revision 196730
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 31#include <sys/cdefs.h> 32__FBSDID("$FreeBSD: head/sys/kern/kern_thread.c 196730 2009-09-01 11:41:51Z kib $"); 33 34#include <sys/param.h> 35#include <sys/systm.h> 36#include <sys/kernel.h> 37#include <sys/lock.h> 38#include <sys/mutex.h> 39#include <sys/proc.h> 40#include <sys/resourcevar.h> 41#include <sys/smp.h> 42#include <sys/sysctl.h> 43#include <sys/sched.h> 44#include <sys/sleepqueue.h> 45#include <sys/selinfo.h> 46#include <sys/turnstile.h> 47#include <sys/ktr.h> 48#include <sys/umtx.h> 49#include <sys/cpuset.h> 50 51#include <security/audit/audit.h> 52 53#include <vm/vm.h> 54#include <vm/vm_extern.h> 55#include <vm/uma.h> 56#include <sys/eventhandler.h> 57 58/* 59 * thread related storage. 60 */ 61static uma_zone_t thread_zone; 62 63SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation"); 64 65int max_threads_per_proc = 1500; 66SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW, 67 &max_threads_per_proc, 0, "Limit on threads per proc"); 68 69int max_threads_hits; 70SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD, 71 &max_threads_hits, 0, ""); 72 73TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 74static struct mtx zombie_lock; 75MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 76 77static void thread_zombie(struct thread *); 78 79struct mtx tid_lock; 80static struct unrhdr *tid_unrhdr; 81 82/* 83 * Prepare a thread for use. 84 */ 85static int 86thread_ctor(void *mem, int size, void *arg, int flags) 87{ 88 struct thread *td; 89 90 td = (struct thread *)mem; 91 td->td_state = TDS_INACTIVE; 92 td->td_oncpu = NOCPU; 93 94 td->td_tid = alloc_unr(tid_unrhdr); 95 td->td_syscalls = 0; 96 97 /* 98 * Note that td_critnest begins life as 1 because the thread is not 99 * running and is thereby implicitly waiting to be on the receiving 100 * end of a context switch. 101 */ 102 td->td_critnest = 1; 103 EVENTHANDLER_INVOKE(thread_ctor, td); 104#ifdef AUDIT 105 audit_thread_alloc(td); 106#endif 107 umtx_thread_alloc(td); 108 return (0); 109} 110 111/* 112 * Reclaim a thread after use. 113 */ 114static void 115thread_dtor(void *mem, int size, void *arg) 116{ 117 struct thread *td; 118 119 td = (struct thread *)mem; 120 121#ifdef INVARIANTS 122 /* Verify that this thread is in a safe state to free. */ 123 switch (td->td_state) { 124 case TDS_INHIBITED: 125 case TDS_RUNNING: 126 case TDS_CAN_RUN: 127 case TDS_RUNQ: 128 /* 129 * We must never unlink a thread that is in one of 130 * these states, because it is currently active. 131 */ 132 panic("bad state for thread unlinking"); 133 /* NOTREACHED */ 134 case TDS_INACTIVE: 135 break; 136 default: 137 panic("bad thread state"); 138 /* NOTREACHED */ 139 } 140#endif 141#ifdef AUDIT 142 audit_thread_free(td); 143#endif 144 /* Free all OSD associated to this thread. */ 145 osd_thread_exit(td); 146 147 EVENTHANDLER_INVOKE(thread_dtor, td); 148 free_unr(tid_unrhdr, td->td_tid); 149} 150 151/* 152 * Initialize type-stable parts of a thread (when newly created). 153 */ 154static int 155thread_init(void *mem, int size, int flags) 156{ 157 struct thread *td; 158 159 td = (struct thread *)mem; 160 161 td->td_sleepqueue = sleepq_alloc(); 162 td->td_turnstile = turnstile_alloc(); 163 EVENTHANDLER_INVOKE(thread_init, td); 164 td->td_sched = (struct td_sched *)&td[1]; 165 umtx_thread_init(td); 166 td->td_kstack = 0; 167 return (0); 168} 169 170/* 171 * Tear down type-stable parts of a thread (just before being discarded). 172 */ 173static void 174thread_fini(void *mem, int size) 175{ 176 struct thread *td; 177 178 td = (struct thread *)mem; 179 EVENTHANDLER_INVOKE(thread_fini, td); 180 turnstile_free(td->td_turnstile); 181 sleepq_free(td->td_sleepqueue); 182 umtx_thread_fini(td); 183 seltdfini(td); 184} 185 186/* 187 * For a newly created process, 188 * link up all the structures and its initial threads etc. 189 * called from: 190 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 191 * proc_dtor() (should go away) 192 * proc_init() 193 */ 194void 195proc_linkup0(struct proc *p, struct thread *td) 196{ 197 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 198 proc_linkup(p, td); 199} 200 201void 202proc_linkup(struct proc *p, struct thread *td) 203{ 204 205 sigqueue_init(&p->p_sigqueue, p); 206 p->p_ksi = ksiginfo_alloc(1); 207 if (p->p_ksi != NULL) { 208 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 209 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 210 } 211 LIST_INIT(&p->p_mqnotifier); 212 p->p_numthreads = 0; 213 thread_link(td, p); 214} 215 216/* 217 * Initialize global thread allocation resources. 218 */ 219void 220threadinit(void) 221{ 222 223 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 224 /* leave one number for thread0 */ 225 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 226 227 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 228 thread_ctor, thread_dtor, thread_init, thread_fini, 229 16 - 1, 0); 230} 231 232/* 233 * Place an unused thread on the zombie list. 234 * Use the slpq as that must be unused by now. 235 */ 236void 237thread_zombie(struct thread *td) 238{ 239 mtx_lock_spin(&zombie_lock); 240 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 241 mtx_unlock_spin(&zombie_lock); 242} 243 244/* 245 * Release a thread that has exited after cpu_throw(). 246 */ 247void 248thread_stash(struct thread *td) 249{ 250 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 251 thread_zombie(td); 252} 253 254/* 255 * Reap zombie resources. 256 */ 257void 258thread_reap(void) 259{ 260 struct thread *td_first, *td_next; 261 262 /* 263 * Don't even bother to lock if none at this instant, 264 * we really don't care about the next instant.. 265 */ 266 if (!TAILQ_EMPTY(&zombie_threads)) { 267 mtx_lock_spin(&zombie_lock); 268 td_first = TAILQ_FIRST(&zombie_threads); 269 if (td_first) 270 TAILQ_INIT(&zombie_threads); 271 mtx_unlock_spin(&zombie_lock); 272 while (td_first) { 273 td_next = TAILQ_NEXT(td_first, td_slpq); 274 if (td_first->td_ucred) 275 crfree(td_first->td_ucred); 276 thread_free(td_first); 277 td_first = td_next; 278 } 279 } 280} 281 282/* 283 * Allocate a thread. 284 */ 285struct thread * 286thread_alloc(int pages) 287{ 288 struct thread *td; 289 290 thread_reap(); /* check if any zombies to get */ 291 292 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 293 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 294 if (!vm_thread_new(td, pages)) { 295 uma_zfree(thread_zone, td); 296 return (NULL); 297 } 298 cpu_thread_alloc(td); 299 return (td); 300} 301 302int 303thread_alloc_stack(struct thread *td, int pages) 304{ 305 306 KASSERT(td->td_kstack == 0, 307 ("thread_alloc_stack called on a thread with kstack")); 308 if (!vm_thread_new(td, pages)) 309 return (0); 310 cpu_thread_alloc(td); 311 return (1); 312} 313 314/* 315 * Deallocate a thread. 316 */ 317void 318thread_free(struct thread *td) 319{ 320 321 lock_profile_thread_exit(td); 322 if (td->td_cpuset) 323 cpuset_rel(td->td_cpuset); 324 td->td_cpuset = NULL; 325 cpu_thread_free(td); 326 if (td->td_kstack != 0) 327 vm_thread_dispose(td); 328 uma_zfree(thread_zone, td); 329} 330 331/* 332 * Discard the current thread and exit from its context. 333 * Always called with scheduler locked. 334 * 335 * Because we can't free a thread while we're operating under its context, 336 * push the current thread into our CPU's deadthread holder. This means 337 * we needn't worry about someone else grabbing our context before we 338 * do a cpu_throw(). 339 */ 340void 341thread_exit(void) 342{ 343 uint64_t new_switchtime; 344 struct thread *td; 345 struct thread *td2; 346 struct proc *p; 347 int wakeup_swapper; 348 349 td = curthread; 350 p = td->td_proc; 351 352 PROC_SLOCK_ASSERT(p, MA_OWNED); 353 mtx_assert(&Giant, MA_NOTOWNED); 354 355 PROC_LOCK_ASSERT(p, MA_OWNED); 356 KASSERT(p != NULL, ("thread exiting without a process")); 357 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 358 (long)p->p_pid, td->td_name); 359 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 360 361#ifdef AUDIT 362 AUDIT_SYSCALL_EXIT(0, td); 363#endif 364 umtx_thread_exit(td); 365 /* 366 * drop FPU & debug register state storage, or any other 367 * architecture specific resources that 368 * would not be on a new untouched process. 369 */ 370 cpu_thread_exit(td); /* XXXSMP */ 371 372 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 373 new_switchtime = cpu_ticks(); 374 p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime)); 375 PCPU_SET(switchtime, new_switchtime); 376 PCPU_SET(switchticks, ticks); 377 PCPU_INC(cnt.v_swtch); 378 /* Save our resource usage in our process. */ 379 td->td_ru.ru_nvcsw++; 380 rucollect(&p->p_ru, &td->td_ru); 381 /* 382 * The last thread is left attached to the process 383 * So that the whole bundle gets recycled. Skip 384 * all this stuff if we never had threads. 385 * EXIT clears all sign of other threads when 386 * it goes to single threading, so the last thread always 387 * takes the short path. 388 */ 389 if (p->p_flag & P_HADTHREADS) { 390 if (p->p_numthreads > 1) { 391 thread_unlink(td); 392 td2 = FIRST_THREAD_IN_PROC(p); 393 sched_exit_thread(td2, td); 394 395 /* 396 * The test below is NOT true if we are the 397 * sole exiting thread. P_STOPPED_SNGL is unset 398 * in exit1() after it is the only survivor. 399 */ 400 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 401 if (p->p_numthreads == p->p_suspcount) { 402 thread_lock(p->p_singlethread); 403 wakeup_swapper = thread_unsuspend_one( 404 p->p_singlethread); 405 thread_unlock(p->p_singlethread); 406 if (wakeup_swapper) 407 kick_proc0(); 408 } 409 } 410 411 atomic_add_int(&td->td_proc->p_exitthreads, 1); 412 PCPU_SET(deadthread, td); 413 } else { 414 /* 415 * The last thread is exiting.. but not through exit() 416 */ 417 panic ("thread_exit: Last thread exiting on its own"); 418 } 419 } 420 PROC_UNLOCK(p); 421 thread_lock(td); 422 /* Save our tick information with both the thread and proc locked */ 423 ruxagg(&p->p_rux, td); 424 PROC_SUNLOCK(p); 425 td->td_state = TDS_INACTIVE; 426#ifdef WITNESS 427 witness_thread_exit(td); 428#endif 429 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 430 sched_throw(td); 431 panic("I'm a teapot!"); 432 /* NOTREACHED */ 433} 434 435/* 436 * Do any thread specific cleanups that may be needed in wait() 437 * called with Giant, proc and schedlock not held. 438 */ 439void 440thread_wait(struct proc *p) 441{ 442 struct thread *td; 443 444 mtx_assert(&Giant, MA_NOTOWNED); 445 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 446 td = FIRST_THREAD_IN_PROC(p); 447 /* Lock the last thread so we spin until it exits cpu_throw(). */ 448 thread_lock(td); 449 thread_unlock(td); 450 /* Wait for any remaining threads to exit cpu_throw(). */ 451 while (p->p_exitthreads) 452 sched_relinquish(curthread); 453 lock_profile_thread_exit(td); 454 cpuset_rel(td->td_cpuset); 455 td->td_cpuset = NULL; 456 cpu_thread_clean(td); 457 crfree(td->td_ucred); 458 thread_reap(); /* check for zombie threads etc. */ 459} 460 461/* 462 * Link a thread to a process. 463 * set up anything that needs to be initialized for it to 464 * be used by the process. 465 */ 466void 467thread_link(struct thread *td, struct proc *p) 468{ 469 470 /* 471 * XXX This can't be enabled because it's called for proc0 before 472 * its lock has been created. 473 * PROC_LOCK_ASSERT(p, MA_OWNED); 474 */ 475 td->td_state = TDS_INACTIVE; 476 td->td_proc = p; 477 td->td_flags = TDF_INMEM; 478 479 LIST_INIT(&td->td_contested); 480 LIST_INIT(&td->td_lprof[0]); 481 LIST_INIT(&td->td_lprof[1]); 482 sigqueue_init(&td->td_sigqueue, p); 483 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 484 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 485 p->p_numthreads++; 486} 487 488/* 489 * Convert a process with one thread to an unthreaded process. 490 */ 491void 492thread_unthread(struct thread *td) 493{ 494 struct proc *p = td->td_proc; 495 496 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 497 p->p_flag &= ~P_HADTHREADS; 498} 499 500/* 501 * Called from: 502 * thread_exit() 503 */ 504void 505thread_unlink(struct thread *td) 506{ 507 struct proc *p = td->td_proc; 508 509 PROC_LOCK_ASSERT(p, MA_OWNED); 510 TAILQ_REMOVE(&p->p_threads, td, td_plist); 511 p->p_numthreads--; 512 /* could clear a few other things here */ 513 /* Must NOT clear links to proc! */ 514} 515 516static int 517calc_remaining(struct proc *p, int mode) 518{ 519 int remaining; 520 521 if (mode == SINGLE_EXIT) 522 remaining = p->p_numthreads; 523 else if (mode == SINGLE_BOUNDARY) 524 remaining = p->p_numthreads - p->p_boundary_count; 525 else if (mode == SINGLE_NO_EXIT) 526 remaining = p->p_numthreads - p->p_suspcount; 527 else 528 panic("calc_remaining: wrong mode %d", mode); 529 return (remaining); 530} 531 532/* 533 * Enforce single-threading. 534 * 535 * Returns 1 if the caller must abort (another thread is waiting to 536 * exit the process or similar). Process is locked! 537 * Returns 0 when you are successfully the only thread running. 538 * A process has successfully single threaded in the suspend mode when 539 * There are no threads in user mode. Threads in the kernel must be 540 * allowed to continue until they get to the user boundary. They may even 541 * copy out their return values and data before suspending. They may however be 542 * accelerated in reaching the user boundary as we will wake up 543 * any sleeping threads that are interruptable. (PCATCH). 544 */ 545int 546thread_single(int mode) 547{ 548 struct thread *td; 549 struct thread *td2; 550 struct proc *p; 551 int remaining, wakeup_swapper; 552 553 td = curthread; 554 p = td->td_proc; 555 mtx_assert(&Giant, MA_NOTOWNED); 556 PROC_LOCK_ASSERT(p, MA_OWNED); 557 KASSERT((td != NULL), ("curthread is NULL")); 558 559 if ((p->p_flag & P_HADTHREADS) == 0) 560 return (0); 561 562 /* Is someone already single threading? */ 563 if (p->p_singlethread != NULL && p->p_singlethread != td) 564 return (1); 565 566 if (mode == SINGLE_EXIT) { 567 p->p_flag |= P_SINGLE_EXIT; 568 p->p_flag &= ~P_SINGLE_BOUNDARY; 569 } else { 570 p->p_flag &= ~P_SINGLE_EXIT; 571 if (mode == SINGLE_BOUNDARY) 572 p->p_flag |= P_SINGLE_BOUNDARY; 573 else 574 p->p_flag &= ~P_SINGLE_BOUNDARY; 575 } 576 p->p_flag |= P_STOPPED_SINGLE; 577 PROC_SLOCK(p); 578 p->p_singlethread = td; 579 remaining = calc_remaining(p, mode); 580 while (remaining != 1) { 581 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 582 goto stopme; 583 wakeup_swapper = 0; 584 FOREACH_THREAD_IN_PROC(p, td2) { 585 if (td2 == td) 586 continue; 587 thread_lock(td2); 588 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 589 if (TD_IS_INHIBITED(td2)) { 590 switch (mode) { 591 case SINGLE_EXIT: 592 if (TD_IS_SUSPENDED(td2)) 593 wakeup_swapper |= 594 thread_unsuspend_one(td2); 595 if (TD_ON_SLEEPQ(td2) && 596 (td2->td_flags & TDF_SINTR)) 597 wakeup_swapper |= 598 sleepq_abort(td2, EINTR); 599 break; 600 case SINGLE_BOUNDARY: 601 if (TD_IS_SUSPENDED(td2) && 602 !(td2->td_flags & TDF_BOUNDARY)) 603 wakeup_swapper |= 604 thread_unsuspend_one(td2); 605 if (TD_ON_SLEEPQ(td2) && 606 (td2->td_flags & TDF_SINTR)) 607 wakeup_swapper |= 608 sleepq_abort(td2, ERESTART); 609 break; 610 case SINGLE_NO_EXIT: 611 if (TD_IS_SUSPENDED(td2) && 612 !(td2->td_flags & TDF_BOUNDARY)) 613 wakeup_swapper |= 614 thread_unsuspend_one(td2); 615 if (TD_ON_SLEEPQ(td2) && 616 (td2->td_flags & TDF_SINTR)) 617 wakeup_swapper |= 618 sleepq_abort(td2, ERESTART); 619 break; 620 default: 621 break; 622 } 623 } 624#ifdef SMP 625 else if (TD_IS_RUNNING(td2) && td != td2) { 626 forward_signal(td2); 627 } 628#endif 629 thread_unlock(td2); 630 } 631 if (wakeup_swapper) 632 kick_proc0(); 633 remaining = calc_remaining(p, mode); 634 635 /* 636 * Maybe we suspended some threads.. was it enough? 637 */ 638 if (remaining == 1) 639 break; 640 641stopme: 642 /* 643 * Wake us up when everyone else has suspended. 644 * In the mean time we suspend as well. 645 */ 646 thread_suspend_switch(td); 647 remaining = calc_remaining(p, mode); 648 } 649 if (mode == SINGLE_EXIT) { 650 /* 651 * We have gotten rid of all the other threads and we 652 * are about to either exit or exec. In either case, 653 * we try our utmost to revert to being a non-threaded 654 * process. 655 */ 656 p->p_singlethread = NULL; 657 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 658 thread_unthread(td); 659 } 660 PROC_SUNLOCK(p); 661 return (0); 662} 663 664/* 665 * Called in from locations that can safely check to see 666 * whether we have to suspend or at least throttle for a 667 * single-thread event (e.g. fork). 668 * 669 * Such locations include userret(). 670 * If the "return_instead" argument is non zero, the thread must be able to 671 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 672 * 673 * The 'return_instead' argument tells the function if it may do a 674 * thread_exit() or suspend, or whether the caller must abort and back 675 * out instead. 676 * 677 * If the thread that set the single_threading request has set the 678 * P_SINGLE_EXIT bit in the process flags then this call will never return 679 * if 'return_instead' is false, but will exit. 680 * 681 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 682 *---------------+--------------------+--------------------- 683 * 0 | returns 0 | returns 0 or 1 684 * | when ST ends | immediatly 685 *---------------+--------------------+--------------------- 686 * 1 | thread exits | returns 1 687 * | | immediatly 688 * 0 = thread_exit() or suspension ok, 689 * other = return error instead of stopping the thread. 690 * 691 * While a full suspension is under effect, even a single threading 692 * thread would be suspended if it made this call (but it shouldn't). 693 * This call should only be made from places where 694 * thread_exit() would be safe as that may be the outcome unless 695 * return_instead is set. 696 */ 697int 698thread_suspend_check(int return_instead) 699{ 700 struct thread *td; 701 struct proc *p; 702 int wakeup_swapper; 703 704 td = curthread; 705 p = td->td_proc; 706 mtx_assert(&Giant, MA_NOTOWNED); 707 PROC_LOCK_ASSERT(p, MA_OWNED); 708 while (P_SHOULDSTOP(p) || 709 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) { 710 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 711 KASSERT(p->p_singlethread != NULL, 712 ("singlethread not set")); 713 /* 714 * The only suspension in action is a 715 * single-threading. Single threader need not stop. 716 * XXX Should be safe to access unlocked 717 * as it can only be set to be true by us. 718 */ 719 if (p->p_singlethread == td) 720 return (0); /* Exempt from stopping. */ 721 } 722 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 723 return (EINTR); 724 725 /* Should we goto user boundary if we didn't come from there? */ 726 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 727 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 728 return (ERESTART); 729 730 /* If thread will exit, flush its pending signals */ 731 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 732 sigqueue_flush(&td->td_sigqueue); 733 734 PROC_SLOCK(p); 735 thread_stopped(p); 736 /* 737 * If the process is waiting for us to exit, 738 * this thread should just suicide. 739 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 740 */ 741 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 742 thread_exit(); 743 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 744 if (p->p_numthreads == p->p_suspcount + 1) { 745 thread_lock(p->p_singlethread); 746 wakeup_swapper = 747 thread_unsuspend_one(p->p_singlethread); 748 thread_unlock(p->p_singlethread); 749 if (wakeup_swapper) 750 kick_proc0(); 751 } 752 } 753 PROC_UNLOCK(p); 754 thread_lock(td); 755 /* 756 * When a thread suspends, it just 757 * gets taken off all queues. 758 */ 759 thread_suspend_one(td); 760 if (return_instead == 0) { 761 p->p_boundary_count++; 762 td->td_flags |= TDF_BOUNDARY; 763 } 764 PROC_SUNLOCK(p); 765 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 766 if (return_instead == 0) 767 td->td_flags &= ~TDF_BOUNDARY; 768 thread_unlock(td); 769 PROC_LOCK(p); 770 if (return_instead == 0) 771 p->p_boundary_count--; 772 } 773 return (0); 774} 775 776void 777thread_suspend_switch(struct thread *td) 778{ 779 struct proc *p; 780 781 p = td->td_proc; 782 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 783 PROC_LOCK_ASSERT(p, MA_OWNED); 784 PROC_SLOCK_ASSERT(p, MA_OWNED); 785 /* 786 * We implement thread_suspend_one in stages here to avoid 787 * dropping the proc lock while the thread lock is owned. 788 */ 789 thread_stopped(p); 790 p->p_suspcount++; 791 PROC_UNLOCK(p); 792 thread_lock(td); 793 td->td_flags &= ~TDF_NEEDSUSPCHK; 794 TD_SET_SUSPENDED(td); 795 sched_sleep(td, 0); 796 PROC_SUNLOCK(p); 797 DROP_GIANT(); 798 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 799 thread_unlock(td); 800 PICKUP_GIANT(); 801 PROC_LOCK(p); 802 PROC_SLOCK(p); 803} 804 805void 806thread_suspend_one(struct thread *td) 807{ 808 struct proc *p = td->td_proc; 809 810 PROC_SLOCK_ASSERT(p, MA_OWNED); 811 THREAD_LOCK_ASSERT(td, MA_OWNED); 812 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 813 p->p_suspcount++; 814 td->td_flags &= ~TDF_NEEDSUSPCHK; 815 TD_SET_SUSPENDED(td); 816 sched_sleep(td, 0); 817} 818 819int 820thread_unsuspend_one(struct thread *td) 821{ 822 struct proc *p = td->td_proc; 823 824 PROC_SLOCK_ASSERT(p, MA_OWNED); 825 THREAD_LOCK_ASSERT(td, MA_OWNED); 826 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 827 TD_CLR_SUSPENDED(td); 828 p->p_suspcount--; 829 return (setrunnable(td)); 830} 831 832/* 833 * Allow all threads blocked by single threading to continue running. 834 */ 835void 836thread_unsuspend(struct proc *p) 837{ 838 struct thread *td; 839 int wakeup_swapper; 840 841 PROC_LOCK_ASSERT(p, MA_OWNED); 842 PROC_SLOCK_ASSERT(p, MA_OWNED); 843 wakeup_swapper = 0; 844 if (!P_SHOULDSTOP(p)) { 845 FOREACH_THREAD_IN_PROC(p, td) { 846 thread_lock(td); 847 if (TD_IS_SUSPENDED(td)) { 848 wakeup_swapper |= thread_unsuspend_one(td); 849 } 850 thread_unlock(td); 851 } 852 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 853 (p->p_numthreads == p->p_suspcount)) { 854 /* 855 * Stopping everything also did the job for the single 856 * threading request. Now we've downgraded to single-threaded, 857 * let it continue. 858 */ 859 thread_lock(p->p_singlethread); 860 wakeup_swapper = thread_unsuspend_one(p->p_singlethread); 861 thread_unlock(p->p_singlethread); 862 } 863 if (wakeup_swapper) 864 kick_proc0(); 865} 866 867/* 868 * End the single threading mode.. 869 */ 870void 871thread_single_end(void) 872{ 873 struct thread *td; 874 struct proc *p; 875 int wakeup_swapper; 876 877 td = curthread; 878 p = td->td_proc; 879 PROC_LOCK_ASSERT(p, MA_OWNED); 880 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 881 PROC_SLOCK(p); 882 p->p_singlethread = NULL; 883 wakeup_swapper = 0; 884 /* 885 * If there are other threads they may now run, 886 * unless of course there is a blanket 'stop order' 887 * on the process. The single threader must be allowed 888 * to continue however as this is a bad place to stop. 889 */ 890 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 891 FOREACH_THREAD_IN_PROC(p, td) { 892 thread_lock(td); 893 if (TD_IS_SUSPENDED(td)) { 894 wakeup_swapper |= thread_unsuspend_one(td); 895 } 896 thread_unlock(td); 897 } 898 } 899 PROC_SUNLOCK(p); 900 if (wakeup_swapper) 901 kick_proc0(); 902} 903 904struct thread * 905thread_find(struct proc *p, lwpid_t tid) 906{ 907 struct thread *td; 908 909 PROC_LOCK_ASSERT(p, MA_OWNED); 910 FOREACH_THREAD_IN_PROC(p, td) { 911 if (td->td_tid == tid) 912 break; 913 } 914 return (td); 915} 916