kern_thread.c revision 293473
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_kdtrace.h" 31#include "opt_hwpmc_hooks.h" 32 33#include <sys/cdefs.h> 34__FBSDID("$FreeBSD: stable/10/sys/kern/kern_thread.c 293473 2016-01-09 14:08:10Z dchagin $"); 35 36#include <sys/param.h> 37#include <sys/systm.h> 38#include <sys/kernel.h> 39#include <sys/lock.h> 40#include <sys/mutex.h> 41#include <sys/proc.h> 42#include <sys/rangelock.h> 43#include <sys/resourcevar.h> 44#include <sys/sdt.h> 45#include <sys/smp.h> 46#include <sys/sched.h> 47#include <sys/sleepqueue.h> 48#include <sys/selinfo.h> 49#include <sys/turnstile.h> 50#include <sys/ktr.h> 51#include <sys/rwlock.h> 52#include <sys/umtx.h> 53#include <sys/cpuset.h> 54#ifdef HWPMC_HOOKS 55#include <sys/pmckern.h> 56#endif 57 58#include <security/audit/audit.h> 59 60#include <vm/vm.h> 61#include <vm/vm_extern.h> 62#include <vm/uma.h> 63#include <sys/eventhandler.h> 64 65SDT_PROVIDER_DECLARE(proc); 66SDT_PROBE_DEFINE(proc, , , lwp__exit); 67 68/* 69 * thread related storage. 70 */ 71static uma_zone_t thread_zone; 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 *); 78static int thread_unsuspend_one(struct thread *td, struct proc *p, 79 bool boundary); 80 81#define TID_BUFFER_SIZE 1024 82 83struct mtx tid_lock; 84static struct unrhdr *tid_unrhdr; 85static lwpid_t tid_buffer[TID_BUFFER_SIZE]; 86static int tid_head, tid_tail; 87static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 88 89struct tidhashhead *tidhashtbl; 90u_long tidhash; 91struct rwlock tidhash_lock; 92 93static lwpid_t 94tid_alloc(void) 95{ 96 lwpid_t tid; 97 98 tid = alloc_unr(tid_unrhdr); 99 if (tid != -1) 100 return (tid); 101 mtx_lock(&tid_lock); 102 if (tid_head == tid_tail) { 103 mtx_unlock(&tid_lock); 104 return (-1); 105 } 106 tid = tid_buffer[tid_head]; 107 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 108 mtx_unlock(&tid_lock); 109 return (tid); 110} 111 112static void 113tid_free(lwpid_t tid) 114{ 115 lwpid_t tmp_tid = -1; 116 117 mtx_lock(&tid_lock); 118 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { 119 tmp_tid = tid_buffer[tid_head]; 120 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 121 } 122 tid_buffer[tid_tail] = tid; 123 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE; 124 mtx_unlock(&tid_lock); 125 if (tmp_tid != -1) 126 free_unr(tid_unrhdr, tmp_tid); 127} 128 129/* 130 * Prepare a thread for use. 131 */ 132static int 133thread_ctor(void *mem, int size, void *arg, int flags) 134{ 135 struct thread *td; 136 137 td = (struct thread *)mem; 138 td->td_state = TDS_INACTIVE; 139 td->td_oncpu = NOCPU; 140 141 td->td_tid = tid_alloc(); 142 143 /* 144 * Note that td_critnest begins life as 1 because the thread is not 145 * running and is thereby implicitly waiting to be on the receiving 146 * end of a context switch. 147 */ 148 td->td_critnest = 1; 149 td->td_lend_user_pri = PRI_MAX; 150 EVENTHANDLER_INVOKE(thread_ctor, td); 151#ifdef AUDIT 152 audit_thread_alloc(td); 153#endif 154 umtx_thread_alloc(td); 155 return (0); 156} 157 158/* 159 * Reclaim a thread after use. 160 */ 161static void 162thread_dtor(void *mem, int size, void *arg) 163{ 164 struct thread *td; 165 166 td = (struct thread *)mem; 167 168#ifdef INVARIANTS 169 /* Verify that this thread is in a safe state to free. */ 170 switch (td->td_state) { 171 case TDS_INHIBITED: 172 case TDS_RUNNING: 173 case TDS_CAN_RUN: 174 case TDS_RUNQ: 175 /* 176 * We must never unlink a thread that is in one of 177 * these states, because it is currently active. 178 */ 179 panic("bad state for thread unlinking"); 180 /* NOTREACHED */ 181 case TDS_INACTIVE: 182 break; 183 default: 184 panic("bad thread state"); 185 /* NOTREACHED */ 186 } 187#endif 188#ifdef AUDIT 189 audit_thread_free(td); 190#endif 191 /* Free all OSD associated to this thread. */ 192 osd_thread_exit(td); 193 194 EVENTHANDLER_INVOKE(thread_dtor, td); 195 tid_free(td->td_tid); 196} 197 198/* 199 * Initialize type-stable parts of a thread (when newly created). 200 */ 201static int 202thread_init(void *mem, int size, int flags) 203{ 204 struct thread *td; 205 206 td = (struct thread *)mem; 207 208 td->td_sleepqueue = sleepq_alloc(); 209 td->td_turnstile = turnstile_alloc(); 210 td->td_rlqe = NULL; 211 EVENTHANDLER_INVOKE(thread_init, td); 212 td->td_sched = (struct td_sched *)&td[1]; 213 umtx_thread_init(td); 214 td->td_kstack = 0; 215 td->td_sel = NULL; 216 return (0); 217} 218 219/* 220 * Tear down type-stable parts of a thread (just before being discarded). 221 */ 222static void 223thread_fini(void *mem, int size) 224{ 225 struct thread *td; 226 227 td = (struct thread *)mem; 228 EVENTHANDLER_INVOKE(thread_fini, td); 229 rlqentry_free(td->td_rlqe); 230 turnstile_free(td->td_turnstile); 231 sleepq_free(td->td_sleepqueue); 232 umtx_thread_fini(td); 233 seltdfini(td); 234} 235 236/* 237 * For a newly created process, 238 * link up all the structures and its initial threads etc. 239 * called from: 240 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 241 * proc_dtor() (should go away) 242 * proc_init() 243 */ 244void 245proc_linkup0(struct proc *p, struct thread *td) 246{ 247 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 248 proc_linkup(p, td); 249} 250 251void 252proc_linkup(struct proc *p, struct thread *td) 253{ 254 255 sigqueue_init(&p->p_sigqueue, p); 256 p->p_ksi = ksiginfo_alloc(1); 257 if (p->p_ksi != NULL) { 258 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 259 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 260 } 261 LIST_INIT(&p->p_mqnotifier); 262 p->p_numthreads = 0; 263 thread_link(td, p); 264} 265 266/* 267 * Initialize global thread allocation resources. 268 */ 269void 270threadinit(void) 271{ 272 273 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 274 275 /* 276 * pid_max cannot be greater than PID_MAX. 277 * leave one number for thread0. 278 */ 279 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 280 281 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 282 thread_ctor, thread_dtor, thread_init, thread_fini, 283 16 - 1, UMA_ZONE_NOFREE); 284 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 285 rw_init(&tidhash_lock, "tidhash"); 286} 287 288/* 289 * Place an unused thread on the zombie list. 290 * Use the slpq as that must be unused by now. 291 */ 292void 293thread_zombie(struct thread *td) 294{ 295 mtx_lock_spin(&zombie_lock); 296 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 297 mtx_unlock_spin(&zombie_lock); 298} 299 300/* 301 * Release a thread that has exited after cpu_throw(). 302 */ 303void 304thread_stash(struct thread *td) 305{ 306 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 307 thread_zombie(td); 308} 309 310/* 311 * Reap zombie resources. 312 */ 313void 314thread_reap(void) 315{ 316 struct thread *td_first, *td_next; 317 318 /* 319 * Don't even bother to lock if none at this instant, 320 * we really don't care about the next instant.. 321 */ 322 if (!TAILQ_EMPTY(&zombie_threads)) { 323 mtx_lock_spin(&zombie_lock); 324 td_first = TAILQ_FIRST(&zombie_threads); 325 if (td_first) 326 TAILQ_INIT(&zombie_threads); 327 mtx_unlock_spin(&zombie_lock); 328 while (td_first) { 329 td_next = TAILQ_NEXT(td_first, td_slpq); 330 if (td_first->td_ucred) 331 crfree(td_first->td_ucred); 332 thread_free(td_first); 333 td_first = td_next; 334 } 335 } 336} 337 338/* 339 * Allocate a thread. 340 */ 341struct thread * 342thread_alloc(int pages) 343{ 344 struct thread *td; 345 346 thread_reap(); /* check if any zombies to get */ 347 348 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 349 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 350 if (!vm_thread_new(td, pages)) { 351 uma_zfree(thread_zone, td); 352 return (NULL); 353 } 354 cpu_thread_alloc(td); 355 return (td); 356} 357 358int 359thread_alloc_stack(struct thread *td, int pages) 360{ 361 362 KASSERT(td->td_kstack == 0, 363 ("thread_alloc_stack called on a thread with kstack")); 364 if (!vm_thread_new(td, pages)) 365 return (0); 366 cpu_thread_alloc(td); 367 return (1); 368} 369 370/* 371 * Deallocate a thread. 372 */ 373void 374thread_free(struct thread *td) 375{ 376 377 lock_profile_thread_exit(td); 378 if (td->td_cpuset) 379 cpuset_rel(td->td_cpuset); 380 td->td_cpuset = NULL; 381 cpu_thread_free(td); 382 if (td->td_kstack != 0) 383 vm_thread_dispose(td); 384 uma_zfree(thread_zone, td); 385} 386 387/* 388 * Discard the current thread and exit from its context. 389 * Always called with scheduler locked. 390 * 391 * Because we can't free a thread while we're operating under its context, 392 * push the current thread into our CPU's deadthread holder. This means 393 * we needn't worry about someone else grabbing our context before we 394 * do a cpu_throw(). 395 */ 396void 397thread_exit(void) 398{ 399 uint64_t runtime, new_switchtime; 400 struct thread *td; 401 struct thread *td2; 402 struct proc *p; 403 int wakeup_swapper; 404 405 td = curthread; 406 p = td->td_proc; 407 408 PROC_SLOCK_ASSERT(p, MA_OWNED); 409 mtx_assert(&Giant, MA_NOTOWNED); 410 411 PROC_LOCK_ASSERT(p, MA_OWNED); 412 KASSERT(p != NULL, ("thread exiting without a process")); 413 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 414 (long)p->p_pid, td->td_name); 415 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 416 417#ifdef AUDIT 418 AUDIT_SYSCALL_EXIT(0, td); 419#endif 420 /* 421 * drop FPU & debug register state storage, or any other 422 * architecture specific resources that 423 * would not be on a new untouched process. 424 */ 425 cpu_thread_exit(td); /* XXXSMP */ 426 427 /* 428 * The last thread is left attached to the process 429 * So that the whole bundle gets recycled. Skip 430 * all this stuff if we never had threads. 431 * EXIT clears all sign of other threads when 432 * it goes to single threading, so the last thread always 433 * takes the short path. 434 */ 435 if (p->p_flag & P_HADTHREADS) { 436 if (p->p_numthreads > 1) { 437 atomic_add_int(&td->td_proc->p_exitthreads, 1); 438 thread_unlink(td); 439 td2 = FIRST_THREAD_IN_PROC(p); 440 sched_exit_thread(td2, td); 441 442 /* 443 * The test below is NOT true if we are the 444 * sole exiting thread. P_STOPPED_SINGLE is unset 445 * in exit1() after it is the only survivor. 446 */ 447 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 448 if (p->p_numthreads == p->p_suspcount) { 449 thread_lock(p->p_singlethread); 450 wakeup_swapper = thread_unsuspend_one( 451 p->p_singlethread, p, false); 452 thread_unlock(p->p_singlethread); 453 if (wakeup_swapper) 454 kick_proc0(); 455 } 456 } 457 458 PCPU_SET(deadthread, td); 459 } else { 460 /* 461 * The last thread is exiting.. but not through exit() 462 */ 463 panic ("thread_exit: Last thread exiting on its own"); 464 } 465 } 466#ifdef HWPMC_HOOKS 467 /* 468 * If this thread is part of a process that is being tracked by hwpmc(4), 469 * inform the module of the thread's impending exit. 470 */ 471 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 472 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 473#endif 474 PROC_UNLOCK(p); 475 PROC_STATLOCK(p); 476 thread_lock(td); 477 PROC_SUNLOCK(p); 478 479 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 480 new_switchtime = cpu_ticks(); 481 runtime = new_switchtime - PCPU_GET(switchtime); 482 td->td_runtime += runtime; 483 td->td_incruntime += runtime; 484 PCPU_SET(switchtime, new_switchtime); 485 PCPU_SET(switchticks, ticks); 486 PCPU_INC(cnt.v_swtch); 487 488 /* Save our resource usage in our process. */ 489 td->td_ru.ru_nvcsw++; 490 ruxagg(p, td); 491 rucollect(&p->p_ru, &td->td_ru); 492 PROC_STATUNLOCK(p); 493 494 td->td_state = TDS_INACTIVE; 495#ifdef WITNESS 496 witness_thread_exit(td); 497#endif 498 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 499 sched_throw(td); 500 panic("I'm a teapot!"); 501 /* NOTREACHED */ 502} 503 504/* 505 * Do any thread specific cleanups that may be needed in wait() 506 * called with Giant, proc and schedlock not held. 507 */ 508void 509thread_wait(struct proc *p) 510{ 511 struct thread *td; 512 513 mtx_assert(&Giant, MA_NOTOWNED); 514 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 515 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 516 td = FIRST_THREAD_IN_PROC(p); 517 /* Lock the last thread so we spin until it exits cpu_throw(). */ 518 thread_lock(td); 519 thread_unlock(td); 520 lock_profile_thread_exit(td); 521 cpuset_rel(td->td_cpuset); 522 td->td_cpuset = NULL; 523 cpu_thread_clean(td); 524 crfree(td->td_ucred); 525 thread_reap(); /* check for zombie threads etc. */ 526} 527 528/* 529 * Link a thread to a process. 530 * set up anything that needs to be initialized for it to 531 * be used by the process. 532 */ 533void 534thread_link(struct thread *td, struct proc *p) 535{ 536 537 /* 538 * XXX This can't be enabled because it's called for proc0 before 539 * its lock has been created. 540 * PROC_LOCK_ASSERT(p, MA_OWNED); 541 */ 542 td->td_state = TDS_INACTIVE; 543 td->td_proc = p; 544 td->td_flags = TDF_INMEM; 545 546 LIST_INIT(&td->td_contested); 547 LIST_INIT(&td->td_lprof[0]); 548 LIST_INIT(&td->td_lprof[1]); 549 sigqueue_init(&td->td_sigqueue, p); 550 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 551 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 552 p->p_numthreads++; 553} 554 555/* 556 * Called from: 557 * thread_exit() 558 */ 559void 560thread_unlink(struct thread *td) 561{ 562 struct proc *p = td->td_proc; 563 564 PROC_LOCK_ASSERT(p, MA_OWNED); 565 TAILQ_REMOVE(&p->p_threads, td, td_plist); 566 p->p_numthreads--; 567 /* could clear a few other things here */ 568 /* Must NOT clear links to proc! */ 569} 570 571static int 572calc_remaining(struct proc *p, int mode) 573{ 574 int remaining; 575 576 PROC_LOCK_ASSERT(p, MA_OWNED); 577 PROC_SLOCK_ASSERT(p, MA_OWNED); 578 if (mode == SINGLE_EXIT) 579 remaining = p->p_numthreads; 580 else if (mode == SINGLE_BOUNDARY) 581 remaining = p->p_numthreads - p->p_boundary_count; 582 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 583 remaining = p->p_numthreads - p->p_suspcount; 584 else 585 panic("calc_remaining: wrong mode %d", mode); 586 return (remaining); 587} 588 589static int 590remain_for_mode(int mode) 591{ 592 593 return (mode == SINGLE_ALLPROC ? 0 : 1); 594} 595 596static int 597weed_inhib(int mode, struct thread *td2, struct proc *p) 598{ 599 int wakeup_swapper; 600 601 PROC_LOCK_ASSERT(p, MA_OWNED); 602 PROC_SLOCK_ASSERT(p, MA_OWNED); 603 THREAD_LOCK_ASSERT(td2, MA_OWNED); 604 605 wakeup_swapper = 0; 606 switch (mode) { 607 case SINGLE_EXIT: 608 if (TD_IS_SUSPENDED(td2)) 609 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 610 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 611 wakeup_swapper |= sleepq_abort(td2, EINTR); 612 break; 613 case SINGLE_BOUNDARY: 614 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 615 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 616 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 617 wakeup_swapper |= sleepq_abort(td2, ERESTART); 618 break; 619 case SINGLE_NO_EXIT: 620 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 621 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 622 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 623 wakeup_swapper |= sleepq_abort(td2, ERESTART); 624 break; 625 case SINGLE_ALLPROC: 626 /* 627 * ALLPROC suspend tries to avoid spurious EINTR for 628 * threads sleeping interruptable, by suspending the 629 * thread directly, similarly to sig_suspend_threads(). 630 * Since such sleep is not performed at the user 631 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 632 * is used to avoid immediate un-suspend. 633 */ 634 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 635 TDF_ALLPROCSUSP)) == 0) 636 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 637 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) { 638 if ((td2->td_flags & TDF_SBDRY) == 0) { 639 thread_suspend_one(td2); 640 td2->td_flags |= TDF_ALLPROCSUSP; 641 } else { 642 wakeup_swapper |= sleepq_abort(td2, ERESTART); 643 } 644 } 645 break; 646 } 647 return (wakeup_swapper); 648} 649 650/* 651 * Enforce single-threading. 652 * 653 * Returns 1 if the caller must abort (another thread is waiting to 654 * exit the process or similar). Process is locked! 655 * Returns 0 when you are successfully the only thread running. 656 * A process has successfully single threaded in the suspend mode when 657 * There are no threads in user mode. Threads in the kernel must be 658 * allowed to continue until they get to the user boundary. They may even 659 * copy out their return values and data before suspending. They may however be 660 * accelerated in reaching the user boundary as we will wake up 661 * any sleeping threads that are interruptable. (PCATCH). 662 */ 663int 664thread_single(struct proc *p, int mode) 665{ 666 struct thread *td; 667 struct thread *td2; 668 int remaining, wakeup_swapper; 669 670 td = curthread; 671 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 672 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 673 ("invalid mode %d", mode)); 674 /* 675 * If allowing non-ALLPROC singlethreading for non-curproc 676 * callers, calc_remaining() and remain_for_mode() should be 677 * adjusted to also account for td->td_proc != p. For now 678 * this is not implemented because it is not used. 679 */ 680 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 681 (mode != SINGLE_ALLPROC && td->td_proc == p), 682 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 683 mtx_assert(&Giant, MA_NOTOWNED); 684 PROC_LOCK_ASSERT(p, MA_OWNED); 685 686 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 687 return (0); 688 689 /* Is someone already single threading? */ 690 if (p->p_singlethread != NULL && p->p_singlethread != td) 691 return (1); 692 693 if (mode == SINGLE_EXIT) { 694 p->p_flag |= P_SINGLE_EXIT; 695 p->p_flag &= ~P_SINGLE_BOUNDARY; 696 } else { 697 p->p_flag &= ~P_SINGLE_EXIT; 698 if (mode == SINGLE_BOUNDARY) 699 p->p_flag |= P_SINGLE_BOUNDARY; 700 else 701 p->p_flag &= ~P_SINGLE_BOUNDARY; 702 } 703 if (mode == SINGLE_ALLPROC) 704 p->p_flag |= P_TOTAL_STOP; 705 p->p_flag |= P_STOPPED_SINGLE; 706 PROC_SLOCK(p); 707 p->p_singlethread = td; 708 remaining = calc_remaining(p, mode); 709 while (remaining != remain_for_mode(mode)) { 710 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 711 goto stopme; 712 wakeup_swapper = 0; 713 FOREACH_THREAD_IN_PROC(p, td2) { 714 if (td2 == td) 715 continue; 716 thread_lock(td2); 717 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 718 if (TD_IS_INHIBITED(td2)) { 719 wakeup_swapper |= weed_inhib(mode, td2, p); 720#ifdef SMP 721 } else if (TD_IS_RUNNING(td2) && td != td2) { 722 forward_signal(td2); 723#endif 724 } 725 thread_unlock(td2); 726 } 727 if (wakeup_swapper) 728 kick_proc0(); 729 remaining = calc_remaining(p, mode); 730 731 /* 732 * Maybe we suspended some threads.. was it enough? 733 */ 734 if (remaining == remain_for_mode(mode)) 735 break; 736 737stopme: 738 /* 739 * Wake us up when everyone else has suspended. 740 * In the mean time we suspend as well. 741 */ 742 thread_suspend_switch(td, p); 743 remaining = calc_remaining(p, mode); 744 } 745 if (mode == SINGLE_EXIT) { 746 /* 747 * Convert the process to an unthreaded process. The 748 * SINGLE_EXIT is called by exit1() or execve(), in 749 * both cases other threads must be retired. 750 */ 751 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 752 p->p_singlethread = NULL; 753 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 754 755 /* 756 * Wait for any remaining threads to exit cpu_throw(). 757 */ 758 while (p->p_exitthreads != 0) { 759 PROC_SUNLOCK(p); 760 PROC_UNLOCK(p); 761 sched_relinquish(td); 762 PROC_LOCK(p); 763 PROC_SLOCK(p); 764 } 765 } else if (mode == SINGLE_BOUNDARY) { 766 /* 767 * Wait until all suspended threads are removed from 768 * the processors. The thread_suspend_check() 769 * increments p_boundary_count while it is still 770 * running, which makes it possible for the execve() 771 * to destroy vmspace while our other threads are 772 * still using the address space. 773 * 774 * We lock the thread, which is only allowed to 775 * succeed after context switch code finished using 776 * the address space. 777 */ 778 FOREACH_THREAD_IN_PROC(p, td2) { 779 if (td2 == td) 780 continue; 781 thread_lock(td2); 782 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 783 ("td %p not on boundary", td2)); 784 KASSERT(TD_IS_SUSPENDED(td2), 785 ("td %p is not suspended", td2)); 786 thread_unlock(td2); 787 } 788 } 789 PROC_SUNLOCK(p); 790 return (0); 791} 792 793bool 794thread_suspend_check_needed(void) 795{ 796 struct proc *p; 797 struct thread *td; 798 799 td = curthread; 800 p = td->td_proc; 801 PROC_LOCK_ASSERT(p, MA_OWNED); 802 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 803 (td->td_dbgflags & TDB_SUSPEND) != 0)); 804} 805 806/* 807 * Called in from locations that can safely check to see 808 * whether we have to suspend or at least throttle for a 809 * single-thread event (e.g. fork). 810 * 811 * Such locations include userret(). 812 * If the "return_instead" argument is non zero, the thread must be able to 813 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 814 * 815 * The 'return_instead' argument tells the function if it may do a 816 * thread_exit() or suspend, or whether the caller must abort and back 817 * out instead. 818 * 819 * If the thread that set the single_threading request has set the 820 * P_SINGLE_EXIT bit in the process flags then this call will never return 821 * if 'return_instead' is false, but will exit. 822 * 823 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 824 *---------------+--------------------+--------------------- 825 * 0 | returns 0 | returns 0 or 1 826 * | when ST ends | immediately 827 *---------------+--------------------+--------------------- 828 * 1 | thread exits | returns 1 829 * | | immediately 830 * 0 = thread_exit() or suspension ok, 831 * other = return error instead of stopping the thread. 832 * 833 * While a full suspension is under effect, even a single threading 834 * thread would be suspended if it made this call (but it shouldn't). 835 * This call should only be made from places where 836 * thread_exit() would be safe as that may be the outcome unless 837 * return_instead is set. 838 */ 839int 840thread_suspend_check(int return_instead) 841{ 842 struct thread *td; 843 struct proc *p; 844 int wakeup_swapper; 845 846 td = curthread; 847 p = td->td_proc; 848 mtx_assert(&Giant, MA_NOTOWNED); 849 PROC_LOCK_ASSERT(p, MA_OWNED); 850 while (thread_suspend_check_needed()) { 851 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 852 KASSERT(p->p_singlethread != NULL, 853 ("singlethread not set")); 854 /* 855 * The only suspension in action is a 856 * single-threading. Single threader need not stop. 857 * XXX Should be safe to access unlocked 858 * as it can only be set to be true by us. 859 */ 860 if (p->p_singlethread == td) 861 return (0); /* Exempt from stopping. */ 862 } 863 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 864 return (EINTR); 865 866 /* Should we goto user boundary if we didn't come from there? */ 867 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 868 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 869 return (ERESTART); 870 871 /* 872 * Ignore suspend requests if they are deferred. 873 */ 874 if ((td->td_flags & TDF_SBDRY) != 0) { 875 KASSERT(return_instead, 876 ("TDF_SBDRY set for unsafe thread_suspend_check")); 877 return (0); 878 } 879 880 /* 881 * If the process is waiting for us to exit, 882 * this thread should just suicide. 883 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 884 */ 885 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 886 PROC_UNLOCK(p); 887 tidhash_remove(td); 888 PROC_LOCK(p); 889 tdsigcleanup(td); 890 umtx_thread_exit(td); 891 PROC_SLOCK(p); 892 thread_stopped(p); 893 thread_exit(); 894 } 895 896 PROC_SLOCK(p); 897 thread_stopped(p); 898 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 899 if (p->p_numthreads == p->p_suspcount + 1) { 900 thread_lock(p->p_singlethread); 901 wakeup_swapper = thread_unsuspend_one( 902 p->p_singlethread, p, false); 903 thread_unlock(p->p_singlethread); 904 if (wakeup_swapper) 905 kick_proc0(); 906 } 907 } 908 PROC_UNLOCK(p); 909 thread_lock(td); 910 /* 911 * When a thread suspends, it just 912 * gets taken off all queues. 913 */ 914 thread_suspend_one(td); 915 if (return_instead == 0) { 916 p->p_boundary_count++; 917 td->td_flags |= TDF_BOUNDARY; 918 } 919 PROC_SUNLOCK(p); 920 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 921 thread_unlock(td); 922 PROC_LOCK(p); 923 } 924 return (0); 925} 926 927void 928thread_suspend_switch(struct thread *td, struct proc *p) 929{ 930 931 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 932 PROC_LOCK_ASSERT(p, MA_OWNED); 933 PROC_SLOCK_ASSERT(p, MA_OWNED); 934 /* 935 * We implement thread_suspend_one in stages here to avoid 936 * dropping the proc lock while the thread lock is owned. 937 */ 938 if (p == td->td_proc) { 939 thread_stopped(p); 940 p->p_suspcount++; 941 } 942 PROC_UNLOCK(p); 943 thread_lock(td); 944 td->td_flags &= ~TDF_NEEDSUSPCHK; 945 TD_SET_SUSPENDED(td); 946 sched_sleep(td, 0); 947 PROC_SUNLOCK(p); 948 DROP_GIANT(); 949 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 950 thread_unlock(td); 951 PICKUP_GIANT(); 952 PROC_LOCK(p); 953 PROC_SLOCK(p); 954} 955 956void 957thread_suspend_one(struct thread *td) 958{ 959 struct proc *p; 960 961 p = td->td_proc; 962 PROC_SLOCK_ASSERT(p, MA_OWNED); 963 THREAD_LOCK_ASSERT(td, MA_OWNED); 964 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 965 p->p_suspcount++; 966 td->td_flags &= ~TDF_NEEDSUSPCHK; 967 TD_SET_SUSPENDED(td); 968 sched_sleep(td, 0); 969} 970 971static int 972thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 973{ 974 975 THREAD_LOCK_ASSERT(td, MA_OWNED); 976 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 977 TD_CLR_SUSPENDED(td); 978 td->td_flags &= ~TDF_ALLPROCSUSP; 979 if (td->td_proc == p) { 980 PROC_SLOCK_ASSERT(p, MA_OWNED); 981 p->p_suspcount--; 982 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 983 td->td_flags &= ~TDF_BOUNDARY; 984 p->p_boundary_count--; 985 } 986 } 987 return (setrunnable(td)); 988} 989 990/* 991 * Allow all threads blocked by single threading to continue running. 992 */ 993void 994thread_unsuspend(struct proc *p) 995{ 996 struct thread *td; 997 int wakeup_swapper; 998 999 PROC_LOCK_ASSERT(p, MA_OWNED); 1000 PROC_SLOCK_ASSERT(p, MA_OWNED); 1001 wakeup_swapper = 0; 1002 if (!P_SHOULDSTOP(p)) { 1003 FOREACH_THREAD_IN_PROC(p, td) { 1004 thread_lock(td); 1005 if (TD_IS_SUSPENDED(td)) { 1006 wakeup_swapper |= thread_unsuspend_one(td, p, 1007 true); 1008 } 1009 thread_unlock(td); 1010 } 1011 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1012 p->p_numthreads == p->p_suspcount) { 1013 /* 1014 * Stopping everything also did the job for the single 1015 * threading request. Now we've downgraded to single-threaded, 1016 * let it continue. 1017 */ 1018 if (p->p_singlethread->td_proc == p) { 1019 thread_lock(p->p_singlethread); 1020 wakeup_swapper = thread_unsuspend_one( 1021 p->p_singlethread, p, false); 1022 thread_unlock(p->p_singlethread); 1023 } 1024 } 1025 if (wakeup_swapper) 1026 kick_proc0(); 1027} 1028 1029/* 1030 * End the single threading mode.. 1031 */ 1032void 1033thread_single_end(struct proc *p, int mode) 1034{ 1035 struct thread *td; 1036 int wakeup_swapper; 1037 1038 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1039 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1040 ("invalid mode %d", mode)); 1041 PROC_LOCK_ASSERT(p, MA_OWNED); 1042 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1043 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1044 ("mode %d does not match P_TOTAL_STOP", mode)); 1045 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1046 ("thread_single_end from other thread %p %p", 1047 curthread, p->p_singlethread)); 1048 KASSERT(mode != SINGLE_BOUNDARY || 1049 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1050 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1051 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1052 P_TOTAL_STOP); 1053 PROC_SLOCK(p); 1054 p->p_singlethread = NULL; 1055 wakeup_swapper = 0; 1056 /* 1057 * If there are other threads they may now run, 1058 * unless of course there is a blanket 'stop order' 1059 * on the process. The single threader must be allowed 1060 * to continue however as this is a bad place to stop. 1061 */ 1062 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1063 FOREACH_THREAD_IN_PROC(p, td) { 1064 thread_lock(td); 1065 if (TD_IS_SUSPENDED(td)) { 1066 wakeup_swapper |= thread_unsuspend_one(td, p, 1067 mode == SINGLE_BOUNDARY); 1068 } 1069 thread_unlock(td); 1070 } 1071 } 1072 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1073 ("inconsistent boundary count %d", p->p_boundary_count)); 1074 PROC_SUNLOCK(p); 1075 if (wakeup_swapper) 1076 kick_proc0(); 1077} 1078 1079struct thread * 1080thread_find(struct proc *p, lwpid_t tid) 1081{ 1082 struct thread *td; 1083 1084 PROC_LOCK_ASSERT(p, MA_OWNED); 1085 FOREACH_THREAD_IN_PROC(p, td) { 1086 if (td->td_tid == tid) 1087 break; 1088 } 1089 return (td); 1090} 1091 1092/* Locate a thread by number; return with proc lock held. */ 1093struct thread * 1094tdfind(lwpid_t tid, pid_t pid) 1095{ 1096#define RUN_THRESH 16 1097 struct thread *td; 1098 int run = 0; 1099 1100 rw_rlock(&tidhash_lock); 1101 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1102 if (td->td_tid == tid) { 1103 if (pid != -1 && td->td_proc->p_pid != pid) { 1104 td = NULL; 1105 break; 1106 } 1107 PROC_LOCK(td->td_proc); 1108 if (td->td_proc->p_state == PRS_NEW) { 1109 PROC_UNLOCK(td->td_proc); 1110 td = NULL; 1111 break; 1112 } 1113 if (run > RUN_THRESH) { 1114 if (rw_try_upgrade(&tidhash_lock)) { 1115 LIST_REMOVE(td, td_hash); 1116 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1117 td, td_hash); 1118 rw_wunlock(&tidhash_lock); 1119 return (td); 1120 } 1121 } 1122 break; 1123 } 1124 run++; 1125 } 1126 rw_runlock(&tidhash_lock); 1127 return (td); 1128} 1129 1130void 1131tidhash_add(struct thread *td) 1132{ 1133 rw_wlock(&tidhash_lock); 1134 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1135 rw_wunlock(&tidhash_lock); 1136} 1137 1138void 1139tidhash_remove(struct thread *td) 1140{ 1141 rw_wlock(&tidhash_lock); 1142 LIST_REMOVE(td, td_hash); 1143 rw_wunlock(&tidhash_lock); 1144} 1145