Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_thread.c
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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: releng/11.1/sys/kern/kern_thread.c 318743 2017-05-23 12:40:50Z badger $"); 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/syscallsubr.h> 49 #include <sys/sysent.h> 50 #include <sys/turnstile.h> 51 #include <sys/ktr.h> 52 #include <sys/rwlock.h> 53 #include <sys/umtx.h> 54 #include <sys/cpuset.h> 55 #ifdef HWPMC_HOOKS 56 #include <sys/pmckern.h> 57 #endif 58 59 #include <security/audit/audit.h> 60 61 #include <vm/vm.h> 62 #include <vm/vm_extern.h> 63 #include <vm/uma.h> 64 #include <vm/vm_domain.h> 65 #include <sys/eventhandler.h> 66 67 /* 68 * Asserts below verify the stability of struct thread and struct proc 69 * layout, as exposed by KBI to modules. On head, the KBI is allowed 70 * to drift, change to the structures must be accompanied by the 71 * assert update. 72 * 73 * On the stable branches after KBI freeze, conditions must not be 74 * violated. Typically new fields are moved to the end of the 75 * structures. 76 */ 77 #ifdef __amd64__ 78 _Static_assert(offsetof(struct thread, td_flags) == 0xe4, 79 "struct thread KBI td_flags"); 80 _Static_assert(offsetof(struct thread, td_pflags) == 0xec, 81 "struct thread KBI td_pflags"); 82 _Static_assert(offsetof(struct thread, td_frame) == 0x418, 83 "struct thread KBI td_frame"); 84 _Static_assert(offsetof(struct thread, td_emuldata) == 0x4c0, 85 "struct thread KBI td_emuldata"); 86 _Static_assert(offsetof(struct proc, p_flag) == 0xb0, 87 "struct proc KBI p_flag"); 88 _Static_assert(offsetof(struct proc, p_pid) == 0xbc, 89 "struct proc KBI p_pid"); 90 _Static_assert(offsetof(struct proc, p_filemon) == 0x3c0, 91 "struct proc KBI p_filemon"); 92 _Static_assert(offsetof(struct proc, p_comm) == 0x3d0, 93 "struct proc KBI p_comm"); 94 _Static_assert(offsetof(struct proc, p_emuldata) == 0x4a0, 95 "struct proc KBI p_emuldata"); 96 #endif 97 #ifdef __i386__ 98 _Static_assert(offsetof(struct thread, td_flags) == 0x8c, 99 "struct thread KBI td_flags"); 100 _Static_assert(offsetof(struct thread, td_pflags) == 0x94, 101 "struct thread KBI td_pflags"); 102 _Static_assert(offsetof(struct thread, td_frame) == 0x2c0, 103 "struct thread KBI td_frame"); 104 _Static_assert(offsetof(struct thread, td_emuldata) == 0x30c, 105 "struct thread KBI td_emuldata"); 106 _Static_assert(offsetof(struct proc, p_flag) == 0x68, 107 "struct proc KBI p_flag"); 108 _Static_assert(offsetof(struct proc, p_pid) == 0x74, 109 "struct proc KBI p_pid"); 110 _Static_assert(offsetof(struct proc, p_filemon) == 0x268, 111 "struct proc KBI p_filemon"); 112 _Static_assert(offsetof(struct proc, p_comm) == 0x274, 113 "struct proc KBI p_comm"); 114 _Static_assert(offsetof(struct proc, p_emuldata) == 0x2f4, 115 "struct proc KBI p_emuldata"); 116 #endif 117 118 SDT_PROVIDER_DECLARE(proc); 119 SDT_PROBE_DEFINE(proc, , , lwp__exit); 120 121 /* 122 * thread related storage. 123 */ 124 static uma_zone_t thread_zone; 125 126 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 127 static struct mtx zombie_lock; 128 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 129 130 static void thread_zombie(struct thread *); 131 static int thread_unsuspend_one(struct thread *td, struct proc *p, 132 bool boundary); 133 134 #define TID_BUFFER_SIZE 1024 135 136 struct mtx tid_lock; 137 static struct unrhdr *tid_unrhdr; 138 static lwpid_t tid_buffer[TID_BUFFER_SIZE]; 139 static int tid_head, tid_tail; 140 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 141 142 struct tidhashhead *tidhashtbl; 143 u_long tidhash; 144 struct rwlock tidhash_lock; 145 146 static lwpid_t 147 tid_alloc(void) 148 { 149 lwpid_t tid; 150 151 tid = alloc_unr(tid_unrhdr); 152 if (tid != -1) 153 return (tid); 154 mtx_lock(&tid_lock); 155 if (tid_head == tid_tail) { 156 mtx_unlock(&tid_lock); 157 return (-1); 158 } 159 tid = tid_buffer[tid_head]; 160 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 161 mtx_unlock(&tid_lock); 162 return (tid); 163 } 164 165 static void 166 tid_free(lwpid_t tid) 167 { 168 lwpid_t tmp_tid = -1; 169 170 mtx_lock(&tid_lock); 171 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { 172 tmp_tid = tid_buffer[tid_head]; 173 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 174 } 175 tid_buffer[tid_tail] = tid; 176 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE; 177 mtx_unlock(&tid_lock); 178 if (tmp_tid != -1) 179 free_unr(tid_unrhdr, tmp_tid); 180 } 181 182 /* 183 * Prepare a thread for use. 184 */ 185 static int 186 thread_ctor(void *mem, int size, void *arg, int flags) 187 { 188 struct thread *td; 189 190 td = (struct thread *)mem; 191 td->td_state = TDS_INACTIVE; 192 td->td_oncpu = NOCPU; 193 194 td->td_tid = tid_alloc(); 195 196 /* 197 * Note that td_critnest begins life as 1 because the thread is not 198 * running and is thereby implicitly waiting to be on the receiving 199 * end of a context switch. 200 */ 201 td->td_critnest = 1; 202 td->td_lend_user_pri = PRI_MAX; 203 EVENTHANDLER_INVOKE(thread_ctor, td); 204 #ifdef AUDIT 205 audit_thread_alloc(td); 206 #endif 207 umtx_thread_alloc(td); 208 return (0); 209 } 210 211 /* 212 * Reclaim a thread after use. 213 */ 214 static void 215 thread_dtor(void *mem, int size, void *arg) 216 { 217 struct thread *td; 218 219 td = (struct thread *)mem; 220 221 #ifdef INVARIANTS 222 /* Verify that this thread is in a safe state to free. */ 223 switch (td->td_state) { 224 case TDS_INHIBITED: 225 case TDS_RUNNING: 226 case TDS_CAN_RUN: 227 case TDS_RUNQ: 228 /* 229 * We must never unlink a thread that is in one of 230 * these states, because it is currently active. 231 */ 232 panic("bad state for thread unlinking"); 233 /* NOTREACHED */ 234 case TDS_INACTIVE: 235 break; 236 default: 237 panic("bad thread state"); 238 /* NOTREACHED */ 239 } 240 #endif 241 #ifdef AUDIT 242 audit_thread_free(td); 243 #endif 244 /* Free all OSD associated to this thread. */ 245 osd_thread_exit(td); 246 td_softdep_cleanup(td); 247 MPASS(td->td_su == NULL); 248 249 EVENTHANDLER_INVOKE(thread_dtor, td); 250 tid_free(td->td_tid); 251 } 252 253 /* 254 * Initialize type-stable parts of a thread (when newly created). 255 */ 256 static int 257 thread_init(void *mem, int size, int flags) 258 { 259 struct thread *td; 260 261 td = (struct thread *)mem; 262 263 td->td_sleepqueue = sleepq_alloc(); 264 td->td_turnstile = turnstile_alloc(); 265 td->td_rlqe = NULL; 266 EVENTHANDLER_INVOKE(thread_init, td); 267 umtx_thread_init(td); 268 td->td_kstack = 0; 269 td->td_sel = NULL; 270 return (0); 271 } 272 273 /* 274 * Tear down type-stable parts of a thread (just before being discarded). 275 */ 276 static void 277 thread_fini(void *mem, int size) 278 { 279 struct thread *td; 280 281 td = (struct thread *)mem; 282 EVENTHANDLER_INVOKE(thread_fini, td); 283 rlqentry_free(td->td_rlqe); 284 turnstile_free(td->td_turnstile); 285 sleepq_free(td->td_sleepqueue); 286 umtx_thread_fini(td); 287 seltdfini(td); 288 } 289 290 /* 291 * For a newly created process, 292 * link up all the structures and its initial threads etc. 293 * called from: 294 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 295 * proc_dtor() (should go away) 296 * proc_init() 297 */ 298 void 299 proc_linkup0(struct proc *p, struct thread *td) 300 { 301 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 302 proc_linkup(p, td); 303 } 304 305 void 306 proc_linkup(struct proc *p, struct thread *td) 307 { 308 309 sigqueue_init(&p->p_sigqueue, p); 310 p->p_ksi = ksiginfo_alloc(1); 311 if (p->p_ksi != NULL) { 312 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 313 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 314 } 315 LIST_INIT(&p->p_mqnotifier); 316 p->p_numthreads = 0; 317 thread_link(td, p); 318 } 319 320 /* 321 * Initialize global thread allocation resources. 322 */ 323 void 324 threadinit(void) 325 { 326 327 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 328 329 /* 330 * pid_max cannot be greater than PID_MAX. 331 * leave one number for thread0. 332 */ 333 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 334 335 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 336 thread_ctor, thread_dtor, thread_init, thread_fini, 337 32 - 1, UMA_ZONE_NOFREE); 338 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 339 rw_init(&tidhash_lock, "tidhash"); 340 } 341 342 /* 343 * Place an unused thread on the zombie list. 344 * Use the slpq as that must be unused by now. 345 */ 346 void 347 thread_zombie(struct thread *td) 348 { 349 mtx_lock_spin(&zombie_lock); 350 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 351 mtx_unlock_spin(&zombie_lock); 352 } 353 354 /* 355 * Release a thread that has exited after cpu_throw(). 356 */ 357 void 358 thread_stash(struct thread *td) 359 { 360 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 361 thread_zombie(td); 362 } 363 364 /* 365 * Reap zombie resources. 366 */ 367 void 368 thread_reap(void) 369 { 370 struct thread *td_first, *td_next; 371 372 /* 373 * Don't even bother to lock if none at this instant, 374 * we really don't care about the next instant. 375 */ 376 if (!TAILQ_EMPTY(&zombie_threads)) { 377 mtx_lock_spin(&zombie_lock); 378 td_first = TAILQ_FIRST(&zombie_threads); 379 if (td_first) 380 TAILQ_INIT(&zombie_threads); 381 mtx_unlock_spin(&zombie_lock); 382 while (td_first) { 383 td_next = TAILQ_NEXT(td_first, td_slpq); 384 thread_cow_free(td_first); 385 thread_free(td_first); 386 td_first = td_next; 387 } 388 } 389 } 390 391 /* 392 * Allocate a thread. 393 */ 394 struct thread * 395 thread_alloc(int pages) 396 { 397 struct thread *td; 398 399 thread_reap(); /* check if any zombies to get */ 400 401 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 402 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 403 if (!vm_thread_new(td, pages)) { 404 uma_zfree(thread_zone, td); 405 return (NULL); 406 } 407 cpu_thread_alloc(td); 408 vm_domain_policy_init(&td->td_vm_dom_policy); 409 return (td); 410 } 411 412 int 413 thread_alloc_stack(struct thread *td, int pages) 414 { 415 416 KASSERT(td->td_kstack == 0, 417 ("thread_alloc_stack called on a thread with kstack")); 418 if (!vm_thread_new(td, pages)) 419 return (0); 420 cpu_thread_alloc(td); 421 return (1); 422 } 423 424 /* 425 * Deallocate a thread. 426 */ 427 void 428 thread_free(struct thread *td) 429 { 430 431 lock_profile_thread_exit(td); 432 if (td->td_cpuset) 433 cpuset_rel(td->td_cpuset); 434 td->td_cpuset = NULL; 435 cpu_thread_free(td); 436 if (td->td_kstack != 0) 437 vm_thread_dispose(td); 438 vm_domain_policy_cleanup(&td->td_vm_dom_policy); 439 callout_drain(&td->td_slpcallout); 440 uma_zfree(thread_zone, td); 441 } 442 443 void 444 thread_cow_get_proc(struct thread *newtd, struct proc *p) 445 { 446 447 PROC_LOCK_ASSERT(p, MA_OWNED); 448 newtd->td_ucred = crhold(p->p_ucred); 449 newtd->td_limit = lim_hold(p->p_limit); 450 newtd->td_cowgen = p->p_cowgen; 451 } 452 453 void 454 thread_cow_get(struct thread *newtd, struct thread *td) 455 { 456 457 newtd->td_ucred = crhold(td->td_ucred); 458 newtd->td_limit = lim_hold(td->td_limit); 459 newtd->td_cowgen = td->td_cowgen; 460 } 461 462 void 463 thread_cow_free(struct thread *td) 464 { 465 466 if (td->td_ucred != NULL) 467 crfree(td->td_ucred); 468 if (td->td_limit != NULL) 469 lim_free(td->td_limit); 470 } 471 472 void 473 thread_cow_update(struct thread *td) 474 { 475 struct proc *p; 476 struct ucred *oldcred; 477 struct plimit *oldlimit; 478 479 p = td->td_proc; 480 oldcred = NULL; 481 oldlimit = NULL; 482 PROC_LOCK(p); 483 if (td->td_ucred != p->p_ucred) { 484 oldcred = td->td_ucred; 485 td->td_ucred = crhold(p->p_ucred); 486 } 487 if (td->td_limit != p->p_limit) { 488 oldlimit = td->td_limit; 489 td->td_limit = lim_hold(p->p_limit); 490 } 491 td->td_cowgen = p->p_cowgen; 492 PROC_UNLOCK(p); 493 if (oldcred != NULL) 494 crfree(oldcred); 495 if (oldlimit != NULL) 496 lim_free(oldlimit); 497 } 498 499 /* 500 * Discard the current thread and exit from its context. 501 * Always called with scheduler locked. 502 * 503 * Because we can't free a thread while we're operating under its context, 504 * push the current thread into our CPU's deadthread holder. This means 505 * we needn't worry about someone else grabbing our context before we 506 * do a cpu_throw(). 507 */ 508 void 509 thread_exit(void) 510 { 511 uint64_t runtime, new_switchtime; 512 struct thread *td; 513 struct thread *td2; 514 struct proc *p; 515 int wakeup_swapper; 516 517 td = curthread; 518 p = td->td_proc; 519 520 PROC_SLOCK_ASSERT(p, MA_OWNED); 521 mtx_assert(&Giant, MA_NOTOWNED); 522 523 PROC_LOCK_ASSERT(p, MA_OWNED); 524 KASSERT(p != NULL, ("thread exiting without a process")); 525 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 526 (long)p->p_pid, td->td_name); 527 SDT_PROBE0(proc, , , lwp__exit); 528 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 529 530 #ifdef AUDIT 531 AUDIT_SYSCALL_EXIT(0, td); 532 #endif 533 /* 534 * drop FPU & debug register state storage, or any other 535 * architecture specific resources that 536 * would not be on a new untouched process. 537 */ 538 cpu_thread_exit(td); 539 540 /* 541 * The last thread is left attached to the process 542 * So that the whole bundle gets recycled. Skip 543 * all this stuff if we never had threads. 544 * EXIT clears all sign of other threads when 545 * it goes to single threading, so the last thread always 546 * takes the short path. 547 */ 548 if (p->p_flag & P_HADTHREADS) { 549 if (p->p_numthreads > 1) { 550 atomic_add_int(&td->td_proc->p_exitthreads, 1); 551 thread_unlink(td); 552 td2 = FIRST_THREAD_IN_PROC(p); 553 sched_exit_thread(td2, td); 554 555 /* 556 * The test below is NOT true if we are the 557 * sole exiting thread. P_STOPPED_SINGLE is unset 558 * in exit1() after it is the only survivor. 559 */ 560 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 561 if (p->p_numthreads == p->p_suspcount) { 562 thread_lock(p->p_singlethread); 563 wakeup_swapper = thread_unsuspend_one( 564 p->p_singlethread, p, false); 565 thread_unlock(p->p_singlethread); 566 if (wakeup_swapper) 567 kick_proc0(); 568 } 569 } 570 571 PCPU_SET(deadthread, td); 572 } else { 573 /* 574 * The last thread is exiting.. but not through exit() 575 */ 576 panic ("thread_exit: Last thread exiting on its own"); 577 } 578 } 579 #ifdef HWPMC_HOOKS 580 /* 581 * If this thread is part of a process that is being tracked by hwpmc(4), 582 * inform the module of the thread's impending exit. 583 */ 584 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 585 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 586 #endif 587 PROC_UNLOCK(p); 588 PROC_STATLOCK(p); 589 thread_lock(td); 590 PROC_SUNLOCK(p); 591 592 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 593 new_switchtime = cpu_ticks(); 594 runtime = new_switchtime - PCPU_GET(switchtime); 595 td->td_runtime += runtime; 596 td->td_incruntime += runtime; 597 PCPU_SET(switchtime, new_switchtime); 598 PCPU_SET(switchticks, ticks); 599 PCPU_INC(cnt.v_swtch); 600 601 /* Save our resource usage in our process. */ 602 td->td_ru.ru_nvcsw++; 603 ruxagg(p, td); 604 rucollect(&p->p_ru, &td->td_ru); 605 PROC_STATUNLOCK(p); 606 607 td->td_state = TDS_INACTIVE; 608 #ifdef WITNESS 609 witness_thread_exit(td); 610 #endif 611 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 612 sched_throw(td); 613 panic("I'm a teapot!"); 614 /* NOTREACHED */ 615 } 616 617 /* 618 * Do any thread specific cleanups that may be needed in wait() 619 * called with Giant, proc and schedlock not held. 620 */ 621 void 622 thread_wait(struct proc *p) 623 { 624 struct thread *td; 625 626 mtx_assert(&Giant, MA_NOTOWNED); 627 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 628 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 629 td = FIRST_THREAD_IN_PROC(p); 630 /* Lock the last thread so we spin until it exits cpu_throw(). */ 631 thread_lock(td); 632 thread_unlock(td); 633 lock_profile_thread_exit(td); 634 cpuset_rel(td->td_cpuset); 635 td->td_cpuset = NULL; 636 cpu_thread_clean(td); 637 thread_cow_free(td); 638 callout_drain(&td->td_slpcallout); 639 thread_reap(); /* check for zombie threads etc. */ 640 } 641 642 /* 643 * Link a thread to a process. 644 * set up anything that needs to be initialized for it to 645 * be used by the process. 646 */ 647 void 648 thread_link(struct thread *td, struct proc *p) 649 { 650 651 /* 652 * XXX This can't be enabled because it's called for proc0 before 653 * its lock has been created. 654 * PROC_LOCK_ASSERT(p, MA_OWNED); 655 */ 656 td->td_state = TDS_INACTIVE; 657 td->td_proc = p; 658 td->td_flags = TDF_INMEM; 659 660 LIST_INIT(&td->td_contested); 661 LIST_INIT(&td->td_lprof[0]); 662 LIST_INIT(&td->td_lprof[1]); 663 sigqueue_init(&td->td_sigqueue, p); 664 callout_init(&td->td_slpcallout, 1); 665 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 666 p->p_numthreads++; 667 } 668 669 /* 670 * Called from: 671 * thread_exit() 672 */ 673 void 674 thread_unlink(struct thread *td) 675 { 676 struct proc *p = td->td_proc; 677 678 PROC_LOCK_ASSERT(p, MA_OWNED); 679 TAILQ_REMOVE(&p->p_threads, td, td_plist); 680 p->p_numthreads--; 681 /* could clear a few other things here */ 682 /* Must NOT clear links to proc! */ 683 } 684 685 static int 686 calc_remaining(struct proc *p, int mode) 687 { 688 int remaining; 689 690 PROC_LOCK_ASSERT(p, MA_OWNED); 691 PROC_SLOCK_ASSERT(p, MA_OWNED); 692 if (mode == SINGLE_EXIT) 693 remaining = p->p_numthreads; 694 else if (mode == SINGLE_BOUNDARY) 695 remaining = p->p_numthreads - p->p_boundary_count; 696 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 697 remaining = p->p_numthreads - p->p_suspcount; 698 else 699 panic("calc_remaining: wrong mode %d", mode); 700 return (remaining); 701 } 702 703 static int 704 remain_for_mode(int mode) 705 { 706 707 return (mode == SINGLE_ALLPROC ? 0 : 1); 708 } 709 710 static int 711 weed_inhib(int mode, struct thread *td2, struct proc *p) 712 { 713 int wakeup_swapper; 714 715 PROC_LOCK_ASSERT(p, MA_OWNED); 716 PROC_SLOCK_ASSERT(p, MA_OWNED); 717 THREAD_LOCK_ASSERT(td2, MA_OWNED); 718 719 wakeup_swapper = 0; 720 switch (mode) { 721 case SINGLE_EXIT: 722 if (TD_IS_SUSPENDED(td2)) 723 wakeup_swapper |= thread_unsuspend_one(td2, p, true); 724 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 725 wakeup_swapper |= sleepq_abort(td2, EINTR); 726 break; 727 case SINGLE_BOUNDARY: 728 case SINGLE_NO_EXIT: 729 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 730 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 731 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 732 wakeup_swapper |= sleepq_abort(td2, ERESTART); 733 break; 734 case SINGLE_ALLPROC: 735 /* 736 * ALLPROC suspend tries to avoid spurious EINTR for 737 * threads sleeping interruptable, by suspending the 738 * thread directly, similarly to sig_suspend_threads(). 739 * Since such sleep is not performed at the user 740 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 741 * is used to avoid immediate un-suspend. 742 */ 743 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 744 TDF_ALLPROCSUSP)) == 0) 745 wakeup_swapper |= thread_unsuspend_one(td2, p, false); 746 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) { 747 if ((td2->td_flags & TDF_SBDRY) == 0) { 748 thread_suspend_one(td2); 749 td2->td_flags |= TDF_ALLPROCSUSP; 750 } else { 751 wakeup_swapper |= sleepq_abort(td2, ERESTART); 752 } 753 } 754 break; 755 } 756 return (wakeup_swapper); 757 } 758 759 /* 760 * Enforce single-threading. 761 * 762 * Returns 1 if the caller must abort (another thread is waiting to 763 * exit the process or similar). Process is locked! 764 * Returns 0 when you are successfully the only thread running. 765 * A process has successfully single threaded in the suspend mode when 766 * There are no threads in user mode. Threads in the kernel must be 767 * allowed to continue until they get to the user boundary. They may even 768 * copy out their return values and data before suspending. They may however be 769 * accelerated in reaching the user boundary as we will wake up 770 * any sleeping threads that are interruptable. (PCATCH). 771 */ 772 int 773 thread_single(struct proc *p, int mode) 774 { 775 struct thread *td; 776 struct thread *td2; 777 int remaining, wakeup_swapper; 778 779 td = curthread; 780 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 781 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 782 ("invalid mode %d", mode)); 783 /* 784 * If allowing non-ALLPROC singlethreading for non-curproc 785 * callers, calc_remaining() and remain_for_mode() should be 786 * adjusted to also account for td->td_proc != p. For now 787 * this is not implemented because it is not used. 788 */ 789 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 790 (mode != SINGLE_ALLPROC && td->td_proc == p), 791 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 792 mtx_assert(&Giant, MA_NOTOWNED); 793 PROC_LOCK_ASSERT(p, MA_OWNED); 794 795 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 796 return (0); 797 798 /* Is someone already single threading? */ 799 if (p->p_singlethread != NULL && p->p_singlethread != td) 800 return (1); 801 802 if (mode == SINGLE_EXIT) { 803 p->p_flag |= P_SINGLE_EXIT; 804 p->p_flag &= ~P_SINGLE_BOUNDARY; 805 } else { 806 p->p_flag &= ~P_SINGLE_EXIT; 807 if (mode == SINGLE_BOUNDARY) 808 p->p_flag |= P_SINGLE_BOUNDARY; 809 else 810 p->p_flag &= ~P_SINGLE_BOUNDARY; 811 } 812 if (mode == SINGLE_ALLPROC) 813 p->p_flag |= P_TOTAL_STOP; 814 p->p_flag |= P_STOPPED_SINGLE; 815 PROC_SLOCK(p); 816 p->p_singlethread = td; 817 remaining = calc_remaining(p, mode); 818 while (remaining != remain_for_mode(mode)) { 819 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 820 goto stopme; 821 wakeup_swapper = 0; 822 FOREACH_THREAD_IN_PROC(p, td2) { 823 if (td2 == td) 824 continue; 825 thread_lock(td2); 826 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 827 if (TD_IS_INHIBITED(td2)) { 828 wakeup_swapper |= weed_inhib(mode, td2, p); 829 #ifdef SMP 830 } else if (TD_IS_RUNNING(td2) && td != td2) { 831 forward_signal(td2); 832 #endif 833 } 834 thread_unlock(td2); 835 } 836 if (wakeup_swapper) 837 kick_proc0(); 838 remaining = calc_remaining(p, mode); 839 840 /* 841 * Maybe we suspended some threads.. was it enough? 842 */ 843 if (remaining == remain_for_mode(mode)) 844 break; 845 846 stopme: 847 /* 848 * Wake us up when everyone else has suspended. 849 * In the mean time we suspend as well. 850 */ 851 thread_suspend_switch(td, p); 852 remaining = calc_remaining(p, mode); 853 } 854 if (mode == SINGLE_EXIT) { 855 /* 856 * Convert the process to an unthreaded process. The 857 * SINGLE_EXIT is called by exit1() or execve(), in 858 * both cases other threads must be retired. 859 */ 860 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 861 p->p_singlethread = NULL; 862 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 863 864 /* 865 * Wait for any remaining threads to exit cpu_throw(). 866 */ 867 while (p->p_exitthreads != 0) { 868 PROC_SUNLOCK(p); 869 PROC_UNLOCK(p); 870 sched_relinquish(td); 871 PROC_LOCK(p); 872 PROC_SLOCK(p); 873 } 874 } else if (mode == SINGLE_BOUNDARY) { 875 /* 876 * Wait until all suspended threads are removed from 877 * the processors. The thread_suspend_check() 878 * increments p_boundary_count while it is still 879 * running, which makes it possible for the execve() 880 * to destroy vmspace while our other threads are 881 * still using the address space. 882 * 883 * We lock the thread, which is only allowed to 884 * succeed after context switch code finished using 885 * the address space. 886 */ 887 FOREACH_THREAD_IN_PROC(p, td2) { 888 if (td2 == td) 889 continue; 890 thread_lock(td2); 891 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 892 ("td %p not on boundary", td2)); 893 KASSERT(TD_IS_SUSPENDED(td2), 894 ("td %p is not suspended", td2)); 895 thread_unlock(td2); 896 } 897 } 898 PROC_SUNLOCK(p); 899 return (0); 900 } 901 902 bool 903 thread_suspend_check_needed(void) 904 { 905 struct proc *p; 906 struct thread *td; 907 908 td = curthread; 909 p = td->td_proc; 910 PROC_LOCK_ASSERT(p, MA_OWNED); 911 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 912 (td->td_dbgflags & TDB_SUSPEND) != 0)); 913 } 914 915 /* 916 * Called in from locations that can safely check to see 917 * whether we have to suspend or at least throttle for a 918 * single-thread event (e.g. fork). 919 * 920 * Such locations include userret(). 921 * If the "return_instead" argument is non zero, the thread must be able to 922 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 923 * 924 * The 'return_instead' argument tells the function if it may do a 925 * thread_exit() or suspend, or whether the caller must abort and back 926 * out instead. 927 * 928 * If the thread that set the single_threading request has set the 929 * P_SINGLE_EXIT bit in the process flags then this call will never return 930 * if 'return_instead' is false, but will exit. 931 * 932 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 933 *---------------+--------------------+--------------------- 934 * 0 | returns 0 | returns 0 or 1 935 * | when ST ends | immediately 936 *---------------+--------------------+--------------------- 937 * 1 | thread exits | returns 1 938 * | | immediately 939 * 0 = thread_exit() or suspension ok, 940 * other = return error instead of stopping the thread. 941 * 942 * While a full suspension is under effect, even a single threading 943 * thread would be suspended if it made this call (but it shouldn't). 944 * This call should only be made from places where 945 * thread_exit() would be safe as that may be the outcome unless 946 * return_instead is set. 947 */ 948 int 949 thread_suspend_check(int return_instead) 950 { 951 struct thread *td; 952 struct proc *p; 953 int wakeup_swapper; 954 955 td = curthread; 956 p = td->td_proc; 957 mtx_assert(&Giant, MA_NOTOWNED); 958 PROC_LOCK_ASSERT(p, MA_OWNED); 959 while (thread_suspend_check_needed()) { 960 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 961 KASSERT(p->p_singlethread != NULL, 962 ("singlethread not set")); 963 /* 964 * The only suspension in action is a 965 * single-threading. Single threader need not stop. 966 * It is safe to access p->p_singlethread unlocked 967 * because it can only be set to our address by us. 968 */ 969 if (p->p_singlethread == td) 970 return (0); /* Exempt from stopping. */ 971 } 972 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 973 return (EINTR); 974 975 /* Should we goto user boundary if we didn't come from there? */ 976 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 977 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 978 return (ERESTART); 979 980 /* 981 * Ignore suspend requests if they are deferred. 982 */ 983 if ((td->td_flags & TDF_SBDRY) != 0) { 984 KASSERT(return_instead, 985 ("TDF_SBDRY set for unsafe thread_suspend_check")); 986 KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 987 (TDF_SEINTR | TDF_SERESTART), 988 ("both TDF_SEINTR and TDF_SERESTART")); 989 return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0); 990 } 991 992 /* 993 * If the process is waiting for us to exit, 994 * this thread should just suicide. 995 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 996 */ 997 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 998 PROC_UNLOCK(p); 999 1000 /* 1001 * Allow Linux emulation layer to do some work 1002 * before thread suicide. 1003 */ 1004 if (__predict_false(p->p_sysent->sv_thread_detach != NULL)) 1005 (p->p_sysent->sv_thread_detach)(td); 1006 umtx_thread_exit(td); 1007 kern_thr_exit(td); 1008 panic("stopped thread did not exit"); 1009 } 1010 1011 PROC_SLOCK(p); 1012 thread_stopped(p); 1013 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 1014 if (p->p_numthreads == p->p_suspcount + 1) { 1015 thread_lock(p->p_singlethread); 1016 wakeup_swapper = thread_unsuspend_one( 1017 p->p_singlethread, p, false); 1018 thread_unlock(p->p_singlethread); 1019 if (wakeup_swapper) 1020 kick_proc0(); 1021 } 1022 } 1023 PROC_UNLOCK(p); 1024 thread_lock(td); 1025 /* 1026 * When a thread suspends, it just 1027 * gets taken off all queues. 1028 */ 1029 thread_suspend_one(td); 1030 if (return_instead == 0) { 1031 p->p_boundary_count++; 1032 td->td_flags |= TDF_BOUNDARY; 1033 } 1034 PROC_SUNLOCK(p); 1035 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 1036 thread_unlock(td); 1037 PROC_LOCK(p); 1038 } 1039 return (0); 1040 } 1041 1042 void 1043 thread_suspend_switch(struct thread *td, struct proc *p) 1044 { 1045 1046 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1047 PROC_LOCK_ASSERT(p, MA_OWNED); 1048 PROC_SLOCK_ASSERT(p, MA_OWNED); 1049 /* 1050 * We implement thread_suspend_one in stages here to avoid 1051 * dropping the proc lock while the thread lock is owned. 1052 */ 1053 if (p == td->td_proc) { 1054 thread_stopped(p); 1055 p->p_suspcount++; 1056 } 1057 PROC_UNLOCK(p); 1058 thread_lock(td); 1059 td->td_flags &= ~TDF_NEEDSUSPCHK; 1060 TD_SET_SUSPENDED(td); 1061 sched_sleep(td, 0); 1062 PROC_SUNLOCK(p); 1063 DROP_GIANT(); 1064 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 1065 thread_unlock(td); 1066 PICKUP_GIANT(); 1067 PROC_LOCK(p); 1068 PROC_SLOCK(p); 1069 } 1070 1071 void 1072 thread_suspend_one(struct thread *td) 1073 { 1074 struct proc *p; 1075 1076 p = td->td_proc; 1077 PROC_SLOCK_ASSERT(p, MA_OWNED); 1078 THREAD_LOCK_ASSERT(td, MA_OWNED); 1079 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 1080 p->p_suspcount++; 1081 td->td_flags &= ~TDF_NEEDSUSPCHK; 1082 TD_SET_SUSPENDED(td); 1083 sched_sleep(td, 0); 1084 } 1085 1086 static int 1087 thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary) 1088 { 1089 1090 THREAD_LOCK_ASSERT(td, MA_OWNED); 1091 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 1092 TD_CLR_SUSPENDED(td); 1093 td->td_flags &= ~TDF_ALLPROCSUSP; 1094 if (td->td_proc == p) { 1095 PROC_SLOCK_ASSERT(p, MA_OWNED); 1096 p->p_suspcount--; 1097 if (boundary && (td->td_flags & TDF_BOUNDARY) != 0) { 1098 td->td_flags &= ~TDF_BOUNDARY; 1099 p->p_boundary_count--; 1100 } 1101 } 1102 return (setrunnable(td)); 1103 } 1104 1105 /* 1106 * Allow all threads blocked by single threading to continue running. 1107 */ 1108 void 1109 thread_unsuspend(struct proc *p) 1110 { 1111 struct thread *td; 1112 int wakeup_swapper; 1113 1114 PROC_LOCK_ASSERT(p, MA_OWNED); 1115 PROC_SLOCK_ASSERT(p, MA_OWNED); 1116 wakeup_swapper = 0; 1117 if (!P_SHOULDSTOP(p)) { 1118 FOREACH_THREAD_IN_PROC(p, td) { 1119 thread_lock(td); 1120 if (TD_IS_SUSPENDED(td)) { 1121 wakeup_swapper |= thread_unsuspend_one(td, p, 1122 true); 1123 } 1124 thread_unlock(td); 1125 } 1126 } else if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 1127 p->p_numthreads == p->p_suspcount) { 1128 /* 1129 * Stopping everything also did the job for the single 1130 * threading request. Now we've downgraded to single-threaded, 1131 * let it continue. 1132 */ 1133 if (p->p_singlethread->td_proc == p) { 1134 thread_lock(p->p_singlethread); 1135 wakeup_swapper = thread_unsuspend_one( 1136 p->p_singlethread, p, false); 1137 thread_unlock(p->p_singlethread); 1138 } 1139 } 1140 if (wakeup_swapper) 1141 kick_proc0(); 1142 } 1143 1144 /* 1145 * End the single threading mode.. 1146 */ 1147 void 1148 thread_single_end(struct proc *p, int mode) 1149 { 1150 struct thread *td; 1151 int wakeup_swapper; 1152 1153 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1154 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1155 ("invalid mode %d", mode)); 1156 PROC_LOCK_ASSERT(p, MA_OWNED); 1157 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1158 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1159 ("mode %d does not match P_TOTAL_STOP", mode)); 1160 KASSERT(mode == SINGLE_ALLPROC || p->p_singlethread == curthread, 1161 ("thread_single_end from other thread %p %p", 1162 curthread, p->p_singlethread)); 1163 KASSERT(mode != SINGLE_BOUNDARY || 1164 (p->p_flag & P_SINGLE_BOUNDARY) != 0, 1165 ("mis-matched SINGLE_BOUNDARY flags %x", p->p_flag)); 1166 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1167 P_TOTAL_STOP); 1168 PROC_SLOCK(p); 1169 p->p_singlethread = NULL; 1170 wakeup_swapper = 0; 1171 /* 1172 * If there are other threads they may now run, 1173 * unless of course there is a blanket 'stop order' 1174 * on the process. The single threader must be allowed 1175 * to continue however as this is a bad place to stop. 1176 */ 1177 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1178 FOREACH_THREAD_IN_PROC(p, td) { 1179 thread_lock(td); 1180 if (TD_IS_SUSPENDED(td)) { 1181 wakeup_swapper |= thread_unsuspend_one(td, p, 1182 mode == SINGLE_BOUNDARY); 1183 } 1184 thread_unlock(td); 1185 } 1186 } 1187 KASSERT(mode != SINGLE_BOUNDARY || p->p_boundary_count == 0, 1188 ("inconsistent boundary count %d", p->p_boundary_count)); 1189 PROC_SUNLOCK(p); 1190 if (wakeup_swapper) 1191 kick_proc0(); 1192 } 1193 1194 struct thread * 1195 thread_find(struct proc *p, lwpid_t tid) 1196 { 1197 struct thread *td; 1198 1199 PROC_LOCK_ASSERT(p, MA_OWNED); 1200 FOREACH_THREAD_IN_PROC(p, td) { 1201 if (td->td_tid == tid) 1202 break; 1203 } 1204 return (td); 1205 } 1206 1207 /* Locate a thread by number; return with proc lock held. */ 1208 struct thread * 1209 tdfind(lwpid_t tid, pid_t pid) 1210 { 1211 #define RUN_THRESH 16 1212 struct thread *td; 1213 int run = 0; 1214 1215 rw_rlock(&tidhash_lock); 1216 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1217 if (td->td_tid == tid) { 1218 if (pid != -1 && td->td_proc->p_pid != pid) { 1219 td = NULL; 1220 break; 1221 } 1222 PROC_LOCK(td->td_proc); 1223 if (td->td_proc->p_state == PRS_NEW) { 1224 PROC_UNLOCK(td->td_proc); 1225 td = NULL; 1226 break; 1227 } 1228 if (run > RUN_THRESH) { 1229 if (rw_try_upgrade(&tidhash_lock)) { 1230 LIST_REMOVE(td, td_hash); 1231 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1232 td, td_hash); 1233 rw_wunlock(&tidhash_lock); 1234 return (td); 1235 } 1236 } 1237 break; 1238 } 1239 run++; 1240 } 1241 rw_runlock(&tidhash_lock); 1242 return (td); 1243 } 1244 1245 void 1246 tidhash_add(struct thread *td) 1247 { 1248 rw_wlock(&tidhash_lock); 1249 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1250 rw_wunlock(&tidhash_lock); 1251 } 1252 1253 void 1254 tidhash_remove(struct thread *td) 1255 { 1256 rw_wlock(&tidhash_lock); 1257 LIST_REMOVE(td, td_hash); 1258 rw_wunlock(&tidhash_lock); 1259 }
Cache object: 7da0336c8a83c5f05af03ffbabc917bb
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