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("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/lock.h> 39 #include <sys/mutex.h> 40 #include <sys/proc.h> 41 #include <sys/rangelock.h> 42 #include <sys/resourcevar.h> 43 #include <sys/sdt.h> 44 #include <sys/smp.h> 45 #include <sys/sched.h> 46 #include <sys/sleepqueue.h> 47 #include <sys/selinfo.h> 48 #include <sys/turnstile.h> 49 #include <sys/ktr.h> 50 #include <sys/rwlock.h> 51 #include <sys/umtx.h> 52 #include <sys/cpuset.h> 53 #ifdef HWPMC_HOOKS 54 #include <sys/pmckern.h> 55 #endif 56 57 #include <security/audit/audit.h> 58 59 #include <vm/vm.h> 60 #include <vm/vm_extern.h> 61 #include <vm/uma.h> 62 #include <sys/eventhandler.h> 63 64 SDT_PROVIDER_DECLARE(proc); 65 SDT_PROBE_DEFINE(proc, , , lwp__exit); 66 67 /* 68 * thread related storage. 69 */ 70 static uma_zone_t thread_zone; 71 72 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 73 static struct mtx zombie_lock; 74 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 75 76 static void thread_zombie(struct thread *); 77 78 #define TID_BUFFER_SIZE 1024 79 80 struct mtx tid_lock; 81 static struct unrhdr *tid_unrhdr; 82 static lwpid_t tid_buffer[TID_BUFFER_SIZE]; 83 static int tid_head, tid_tail; 84 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 85 86 struct tidhashhead *tidhashtbl; 87 u_long tidhash; 88 struct rwlock tidhash_lock; 89 90 static lwpid_t 91 tid_alloc(void) 92 { 93 lwpid_t tid; 94 95 tid = alloc_unr(tid_unrhdr); 96 if (tid != -1) 97 return (tid); 98 mtx_lock(&tid_lock); 99 if (tid_head == tid_tail) { 100 mtx_unlock(&tid_lock); 101 return (-1); 102 } 103 tid = tid_buffer[tid_head]; 104 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 105 mtx_unlock(&tid_lock); 106 return (tid); 107 } 108 109 static void 110 tid_free(lwpid_t tid) 111 { 112 lwpid_t tmp_tid = -1; 113 114 mtx_lock(&tid_lock); 115 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { 116 tmp_tid = tid_buffer[tid_head]; 117 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 118 } 119 tid_buffer[tid_tail] = tid; 120 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE; 121 mtx_unlock(&tid_lock); 122 if (tmp_tid != -1) 123 free_unr(tid_unrhdr, tmp_tid); 124 } 125 126 /* 127 * Prepare a thread for use. 128 */ 129 static int 130 thread_ctor(void *mem, int size, void *arg, int flags) 131 { 132 struct thread *td; 133 134 td = (struct thread *)mem; 135 td->td_state = TDS_INACTIVE; 136 td->td_oncpu = NOCPU; 137 138 td->td_tid = tid_alloc(); 139 140 /* 141 * Note that td_critnest begins life as 1 because the thread is not 142 * running and is thereby implicitly waiting to be on the receiving 143 * end of a context switch. 144 */ 145 td->td_critnest = 1; 146 td->td_lend_user_pri = PRI_MAX; 147 EVENTHANDLER_INVOKE(thread_ctor, td); 148 #ifdef AUDIT 149 audit_thread_alloc(td); 150 #endif 151 umtx_thread_alloc(td); 152 return (0); 153 } 154 155 /* 156 * Reclaim a thread after use. 157 */ 158 static void 159 thread_dtor(void *mem, int size, void *arg) 160 { 161 struct thread *td; 162 163 td = (struct thread *)mem; 164 165 #ifdef INVARIANTS 166 /* Verify that this thread is in a safe state to free. */ 167 switch (td->td_state) { 168 case TDS_INHIBITED: 169 case TDS_RUNNING: 170 case TDS_CAN_RUN: 171 case TDS_RUNQ: 172 /* 173 * We must never unlink a thread that is in one of 174 * these states, because it is currently active. 175 */ 176 panic("bad state for thread unlinking"); 177 /* NOTREACHED */ 178 case TDS_INACTIVE: 179 break; 180 default: 181 panic("bad thread state"); 182 /* NOTREACHED */ 183 } 184 #endif 185 #ifdef AUDIT 186 audit_thread_free(td); 187 #endif 188 /* Free all OSD associated to this thread. */ 189 osd_thread_exit(td); 190 191 EVENTHANDLER_INVOKE(thread_dtor, td); 192 tid_free(td->td_tid); 193 } 194 195 /* 196 * Initialize type-stable parts of a thread (when newly created). 197 */ 198 static int 199 thread_init(void *mem, int size, int flags) 200 { 201 struct thread *td; 202 203 td = (struct thread *)mem; 204 205 td->td_sleepqueue = sleepq_alloc(); 206 td->td_turnstile = turnstile_alloc(); 207 td->td_rlqe = NULL; 208 EVENTHANDLER_INVOKE(thread_init, td); 209 td->td_sched = (struct td_sched *)&td[1]; 210 umtx_thread_init(td); 211 td->td_kstack = 0; 212 td->td_sel = NULL; 213 return (0); 214 } 215 216 /* 217 * Tear down type-stable parts of a thread (just before being discarded). 218 */ 219 static void 220 thread_fini(void *mem, int size) 221 { 222 struct thread *td; 223 224 td = (struct thread *)mem; 225 EVENTHANDLER_INVOKE(thread_fini, td); 226 rlqentry_free(td->td_rlqe); 227 turnstile_free(td->td_turnstile); 228 sleepq_free(td->td_sleepqueue); 229 umtx_thread_fini(td); 230 seltdfini(td); 231 } 232 233 /* 234 * For a newly created process, 235 * link up all the structures and its initial threads etc. 236 * called from: 237 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 238 * proc_dtor() (should go away) 239 * proc_init() 240 */ 241 void 242 proc_linkup0(struct proc *p, struct thread *td) 243 { 244 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 245 proc_linkup(p, td); 246 } 247 248 void 249 proc_linkup(struct proc *p, struct thread *td) 250 { 251 252 sigqueue_init(&p->p_sigqueue, p); 253 p->p_ksi = ksiginfo_alloc(1); 254 if (p->p_ksi != NULL) { 255 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 256 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 257 } 258 LIST_INIT(&p->p_mqnotifier); 259 p->p_numthreads = 0; 260 thread_link(td, p); 261 } 262 263 /* 264 * Initialize global thread allocation resources. 265 */ 266 void 267 threadinit(void) 268 { 269 270 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 271 272 /* 273 * pid_max cannot be greater than PID_MAX. 274 * leave one number for thread0. 275 */ 276 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 277 278 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 279 thread_ctor, thread_dtor, thread_init, thread_fini, 280 16 - 1, 0); 281 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 282 rw_init(&tidhash_lock, "tidhash"); 283 } 284 285 /* 286 * Place an unused thread on the zombie list. 287 * Use the slpq as that must be unused by now. 288 */ 289 void 290 thread_zombie(struct thread *td) 291 { 292 mtx_lock_spin(&zombie_lock); 293 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 294 mtx_unlock_spin(&zombie_lock); 295 } 296 297 /* 298 * Release a thread that has exited after cpu_throw(). 299 */ 300 void 301 thread_stash(struct thread *td) 302 { 303 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 304 thread_zombie(td); 305 } 306 307 /* 308 * Reap zombie resources. 309 */ 310 void 311 thread_reap(void) 312 { 313 struct thread *td_first, *td_next; 314 315 /* 316 * Don't even bother to lock if none at this instant, 317 * we really don't care about the next instant.. 318 */ 319 if (!TAILQ_EMPTY(&zombie_threads)) { 320 mtx_lock_spin(&zombie_lock); 321 td_first = TAILQ_FIRST(&zombie_threads); 322 if (td_first) 323 TAILQ_INIT(&zombie_threads); 324 mtx_unlock_spin(&zombie_lock); 325 while (td_first) { 326 td_next = TAILQ_NEXT(td_first, td_slpq); 327 if (td_first->td_ucred) 328 crfree(td_first->td_ucred); 329 thread_free(td_first); 330 td_first = td_next; 331 } 332 } 333 } 334 335 /* 336 * Allocate a thread. 337 */ 338 struct thread * 339 thread_alloc(int pages) 340 { 341 struct thread *td; 342 343 thread_reap(); /* check if any zombies to get */ 344 345 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 346 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 347 if (!vm_thread_new(td, pages)) { 348 uma_zfree(thread_zone, td); 349 return (NULL); 350 } 351 cpu_thread_alloc(td); 352 return (td); 353 } 354 355 int 356 thread_alloc_stack(struct thread *td, int pages) 357 { 358 359 KASSERT(td->td_kstack == 0, 360 ("thread_alloc_stack called on a thread with kstack")); 361 if (!vm_thread_new(td, pages)) 362 return (0); 363 cpu_thread_alloc(td); 364 return (1); 365 } 366 367 /* 368 * Deallocate a thread. 369 */ 370 void 371 thread_free(struct thread *td) 372 { 373 374 lock_profile_thread_exit(td); 375 if (td->td_cpuset) 376 cpuset_rel(td->td_cpuset); 377 td->td_cpuset = NULL; 378 cpu_thread_free(td); 379 if (td->td_kstack != 0) 380 vm_thread_dispose(td); 381 uma_zfree(thread_zone, td); 382 } 383 384 /* 385 * Discard the current thread and exit from its context. 386 * Always called with scheduler locked. 387 * 388 * Because we can't free a thread while we're operating under its context, 389 * push the current thread into our CPU's deadthread holder. This means 390 * we needn't worry about someone else grabbing our context before we 391 * do a cpu_throw(). 392 */ 393 void 394 thread_exit(void) 395 { 396 uint64_t runtime, new_switchtime; 397 struct thread *td; 398 struct thread *td2; 399 struct proc *p; 400 int wakeup_swapper; 401 402 td = curthread; 403 p = td->td_proc; 404 405 PROC_SLOCK_ASSERT(p, MA_OWNED); 406 mtx_assert(&Giant, MA_NOTOWNED); 407 408 PROC_LOCK_ASSERT(p, MA_OWNED); 409 KASSERT(p != NULL, ("thread exiting without a process")); 410 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 411 (long)p->p_pid, td->td_name); 412 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 413 414 #ifdef AUDIT 415 AUDIT_SYSCALL_EXIT(0, td); 416 #endif 417 /* 418 * drop FPU & debug register state storage, or any other 419 * architecture specific resources that 420 * would not be on a new untouched process. 421 */ 422 cpu_thread_exit(td); /* XXXSMP */ 423 424 /* 425 * The last thread is left attached to the process 426 * So that the whole bundle gets recycled. Skip 427 * all this stuff if we never had threads. 428 * EXIT clears all sign of other threads when 429 * it goes to single threading, so the last thread always 430 * takes the short path. 431 */ 432 if (p->p_flag & P_HADTHREADS) { 433 if (p->p_numthreads > 1) { 434 atomic_add_int(&td->td_proc->p_exitthreads, 1); 435 thread_unlink(td); 436 td2 = FIRST_THREAD_IN_PROC(p); 437 sched_exit_thread(td2, td); 438 439 /* 440 * The test below is NOT true if we are the 441 * sole exiting thread. P_STOPPED_SINGLE is unset 442 * in exit1() after it is the only survivor. 443 */ 444 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 445 if (p->p_numthreads == p->p_suspcount) { 446 thread_lock(p->p_singlethread); 447 wakeup_swapper = thread_unsuspend_one( 448 p->p_singlethread, p); 449 thread_unlock(p->p_singlethread); 450 if (wakeup_swapper) 451 kick_proc0(); 452 } 453 } 454 455 PCPU_SET(deadthread, td); 456 } else { 457 /* 458 * The last thread is exiting.. but not through exit() 459 */ 460 panic ("thread_exit: Last thread exiting on its own"); 461 } 462 } 463 #ifdef HWPMC_HOOKS 464 /* 465 * If this thread is part of a process that is being tracked by hwpmc(4), 466 * inform the module of the thread's impending exit. 467 */ 468 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 469 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 470 #endif 471 PROC_UNLOCK(p); 472 PROC_STATLOCK(p); 473 thread_lock(td); 474 PROC_SUNLOCK(p); 475 476 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 477 new_switchtime = cpu_ticks(); 478 runtime = new_switchtime - PCPU_GET(switchtime); 479 td->td_runtime += runtime; 480 td->td_incruntime += runtime; 481 PCPU_SET(switchtime, new_switchtime); 482 PCPU_SET(switchticks, ticks); 483 PCPU_INC(cnt.v_swtch); 484 485 /* Save our resource usage in our process. */ 486 td->td_ru.ru_nvcsw++; 487 ruxagg(p, td); 488 rucollect(&p->p_ru, &td->td_ru); 489 PROC_STATUNLOCK(p); 490 491 td->td_state = TDS_INACTIVE; 492 #ifdef WITNESS 493 witness_thread_exit(td); 494 #endif 495 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 496 sched_throw(td); 497 panic("I'm a teapot!"); 498 /* NOTREACHED */ 499 } 500 501 /* 502 * Do any thread specific cleanups that may be needed in wait() 503 * called with Giant, proc and schedlock not held. 504 */ 505 void 506 thread_wait(struct proc *p) 507 { 508 struct thread *td; 509 510 mtx_assert(&Giant, MA_NOTOWNED); 511 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 512 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 513 td = FIRST_THREAD_IN_PROC(p); 514 /* Lock the last thread so we spin until it exits cpu_throw(). */ 515 thread_lock(td); 516 thread_unlock(td); 517 lock_profile_thread_exit(td); 518 cpuset_rel(td->td_cpuset); 519 td->td_cpuset = NULL; 520 cpu_thread_clean(td); 521 crfree(td->td_ucred); 522 thread_reap(); /* check for zombie threads etc. */ 523 } 524 525 /* 526 * Link a thread to a process. 527 * set up anything that needs to be initialized for it to 528 * be used by the process. 529 */ 530 void 531 thread_link(struct thread *td, struct proc *p) 532 { 533 534 /* 535 * XXX This can't be enabled because it's called for proc0 before 536 * its lock has been created. 537 * PROC_LOCK_ASSERT(p, MA_OWNED); 538 */ 539 td->td_state = TDS_INACTIVE; 540 td->td_proc = p; 541 td->td_flags = TDF_INMEM; 542 543 LIST_INIT(&td->td_contested); 544 LIST_INIT(&td->td_lprof[0]); 545 LIST_INIT(&td->td_lprof[1]); 546 sigqueue_init(&td->td_sigqueue, p); 547 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 548 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 549 p->p_numthreads++; 550 } 551 552 /* 553 * Called from: 554 * thread_exit() 555 */ 556 void 557 thread_unlink(struct thread *td) 558 { 559 struct proc *p = td->td_proc; 560 561 PROC_LOCK_ASSERT(p, MA_OWNED); 562 TAILQ_REMOVE(&p->p_threads, td, td_plist); 563 p->p_numthreads--; 564 /* could clear a few other things here */ 565 /* Must NOT clear links to proc! */ 566 } 567 568 static int 569 calc_remaining(struct proc *p, int mode) 570 { 571 int remaining; 572 573 PROC_LOCK_ASSERT(p, MA_OWNED); 574 PROC_SLOCK_ASSERT(p, MA_OWNED); 575 if (mode == SINGLE_EXIT) 576 remaining = p->p_numthreads; 577 else if (mode == SINGLE_BOUNDARY) 578 remaining = p->p_numthreads - p->p_boundary_count; 579 else if (mode == SINGLE_NO_EXIT || mode == SINGLE_ALLPROC) 580 remaining = p->p_numthreads - p->p_suspcount; 581 else 582 panic("calc_remaining: wrong mode %d", mode); 583 return (remaining); 584 } 585 586 static int 587 remain_for_mode(int mode) 588 { 589 590 return (mode == SINGLE_ALLPROC ? 0 : 1); 591 } 592 593 static int 594 weed_inhib(int mode, struct thread *td2, struct proc *p) 595 { 596 int wakeup_swapper; 597 598 PROC_LOCK_ASSERT(p, MA_OWNED); 599 PROC_SLOCK_ASSERT(p, MA_OWNED); 600 THREAD_LOCK_ASSERT(td2, MA_OWNED); 601 602 wakeup_swapper = 0; 603 switch (mode) { 604 case SINGLE_EXIT: 605 if (TD_IS_SUSPENDED(td2)) 606 wakeup_swapper |= thread_unsuspend_one(td2, p); 607 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 608 wakeup_swapper |= sleepq_abort(td2, EINTR); 609 break; 610 case SINGLE_BOUNDARY: 611 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 612 wakeup_swapper |= thread_unsuspend_one(td2, p); 613 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 614 wakeup_swapper |= sleepq_abort(td2, ERESTART); 615 break; 616 case SINGLE_NO_EXIT: 617 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 618 wakeup_swapper |= thread_unsuspend_one(td2, p); 619 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 620 wakeup_swapper |= sleepq_abort(td2, ERESTART); 621 break; 622 case SINGLE_ALLPROC: 623 /* 624 * ALLPROC suspend tries to avoid spurious EINTR for 625 * threads sleeping interruptable, by suspending the 626 * thread directly, similarly to sig_suspend_threads(). 627 * Since such sleep is not performed at the user 628 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 629 * is used to avoid immediate un-suspend. 630 */ 631 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 632 TDF_ALLPROCSUSP)) == 0) 633 wakeup_swapper |= thread_unsuspend_one(td2, p); 634 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) { 635 if ((td2->td_flags & TDF_SBDRY) == 0) { 636 thread_suspend_one(td2); 637 td2->td_flags |= TDF_ALLPROCSUSP; 638 } else { 639 wakeup_swapper |= sleepq_abort(td2, ERESTART); 640 } 641 } 642 break; 643 } 644 return (wakeup_swapper); 645 } 646 647 /* 648 * Enforce single-threading. 649 * 650 * Returns 1 if the caller must abort (another thread is waiting to 651 * exit the process or similar). Process is locked! 652 * Returns 0 when you are successfully the only thread running. 653 * A process has successfully single threaded in the suspend mode when 654 * There are no threads in user mode. Threads in the kernel must be 655 * allowed to continue until they get to the user boundary. They may even 656 * copy out their return values and data before suspending. They may however be 657 * accelerated in reaching the user boundary as we will wake up 658 * any sleeping threads that are interruptable. (PCATCH). 659 */ 660 int 661 thread_single(struct proc *p, int mode) 662 { 663 struct thread *td; 664 struct thread *td2; 665 int remaining, wakeup_swapper; 666 667 td = curthread; 668 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 669 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 670 ("invalid mode %d", mode)); 671 /* 672 * If allowing non-ALLPROC singlethreading for non-curproc 673 * callers, calc_remaining() and remain_for_mode() should be 674 * adjusted to also account for td->td_proc != p. For now 675 * this is not implemented because it is not used. 676 */ 677 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 678 (mode != SINGLE_ALLPROC && td->td_proc == p), 679 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 680 mtx_assert(&Giant, MA_NOTOWNED); 681 PROC_LOCK_ASSERT(p, MA_OWNED); 682 683 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 684 return (0); 685 686 /* Is someone already single threading? */ 687 if (p->p_singlethread != NULL && p->p_singlethread != td) 688 return (1); 689 690 if (mode == SINGLE_EXIT) { 691 p->p_flag |= P_SINGLE_EXIT; 692 p->p_flag &= ~P_SINGLE_BOUNDARY; 693 } else { 694 p->p_flag &= ~P_SINGLE_EXIT; 695 if (mode == SINGLE_BOUNDARY) 696 p->p_flag |= P_SINGLE_BOUNDARY; 697 else 698 p->p_flag &= ~P_SINGLE_BOUNDARY; 699 } 700 if (mode == SINGLE_ALLPROC) 701 p->p_flag |= P_TOTAL_STOP; 702 p->p_flag |= P_STOPPED_SINGLE; 703 PROC_SLOCK(p); 704 p->p_singlethread = td; 705 remaining = calc_remaining(p, mode); 706 while (remaining != remain_for_mode(mode)) { 707 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 708 goto stopme; 709 wakeup_swapper = 0; 710 FOREACH_THREAD_IN_PROC(p, td2) { 711 if (td2 == td) 712 continue; 713 thread_lock(td2); 714 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 715 if (TD_IS_INHIBITED(td2)) { 716 wakeup_swapper |= weed_inhib(mode, td2, p); 717 #ifdef SMP 718 } else if (TD_IS_RUNNING(td2) && td != td2) { 719 forward_signal(td2); 720 #endif 721 } 722 thread_unlock(td2); 723 } 724 if (wakeup_swapper) 725 kick_proc0(); 726 remaining = calc_remaining(p, mode); 727 728 /* 729 * Maybe we suspended some threads.. was it enough? 730 */ 731 if (remaining == remain_for_mode(mode)) 732 break; 733 734 stopme: 735 /* 736 * Wake us up when everyone else has suspended. 737 * In the mean time we suspend as well. 738 */ 739 thread_suspend_switch(td, p); 740 remaining = calc_remaining(p, mode); 741 } 742 if (mode == SINGLE_EXIT) { 743 /* 744 * Convert the process to an unthreaded process. The 745 * SINGLE_EXIT is called by exit1() or execve(), in 746 * both cases other threads must be retired. 747 */ 748 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 749 p->p_singlethread = NULL; 750 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 751 752 /* 753 * Wait for any remaining threads to exit cpu_throw(). 754 */ 755 while (p->p_exitthreads != 0) { 756 PROC_SUNLOCK(p); 757 PROC_UNLOCK(p); 758 sched_relinquish(td); 759 PROC_LOCK(p); 760 PROC_SLOCK(p); 761 } 762 } else if (mode == SINGLE_BOUNDARY) { 763 /* 764 * Wait until all suspended threads are removed from 765 * the processors. The thread_suspend_check() 766 * increments p_boundary_count while it is still 767 * running, which makes it possible for the execve() 768 * to destroy vmspace while our other threads are 769 * still using the address space. 770 * 771 * We lock the thread, which is only allowed to 772 * succeed after context switch code finished using 773 * the address space. 774 */ 775 FOREACH_THREAD_IN_PROC(p, td2) { 776 if (td2 == td) 777 continue; 778 thread_lock(td2); 779 KASSERT((td2->td_flags & TDF_BOUNDARY) != 0, 780 ("td %p not on boundary", td2)); 781 KASSERT(TD_IS_SUSPENDED(td2), 782 ("td %p is not suspended", td2)); 783 thread_unlock(td2); 784 } 785 } 786 PROC_SUNLOCK(p); 787 return (0); 788 } 789 790 bool 791 thread_suspend_check_needed(void) 792 { 793 struct proc *p; 794 struct thread *td; 795 796 td = curthread; 797 p = td->td_proc; 798 PROC_LOCK_ASSERT(p, MA_OWNED); 799 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 800 (td->td_dbgflags & TDB_SUSPEND) != 0)); 801 } 802 803 /* 804 * Called in from locations that can safely check to see 805 * whether we have to suspend or at least throttle for a 806 * single-thread event (e.g. fork). 807 * 808 * Such locations include userret(). 809 * If the "return_instead" argument is non zero, the thread must be able to 810 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 811 * 812 * The 'return_instead' argument tells the function if it may do a 813 * thread_exit() or suspend, or whether the caller must abort and back 814 * out instead. 815 * 816 * If the thread that set the single_threading request has set the 817 * P_SINGLE_EXIT bit in the process flags then this call will never return 818 * if 'return_instead' is false, but will exit. 819 * 820 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 821 *---------------+--------------------+--------------------- 822 * 0 | returns 0 | returns 0 or 1 823 * | when ST ends | immediately 824 *---------------+--------------------+--------------------- 825 * 1 | thread exits | returns 1 826 * | | immediately 827 * 0 = thread_exit() or suspension ok, 828 * other = return error instead of stopping the thread. 829 * 830 * While a full suspension is under effect, even a single threading 831 * thread would be suspended if it made this call (but it shouldn't). 832 * This call should only be made from places where 833 * thread_exit() would be safe as that may be the outcome unless 834 * return_instead is set. 835 */ 836 int 837 thread_suspend_check(int return_instead) 838 { 839 struct thread *td; 840 struct proc *p; 841 int wakeup_swapper; 842 843 td = curthread; 844 p = td->td_proc; 845 mtx_assert(&Giant, MA_NOTOWNED); 846 PROC_LOCK_ASSERT(p, MA_OWNED); 847 while (thread_suspend_check_needed()) { 848 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 849 KASSERT(p->p_singlethread != NULL, 850 ("singlethread not set")); 851 /* 852 * The only suspension in action is a 853 * single-threading. Single threader need not stop. 854 * XXX Should be safe to access unlocked 855 * as it can only be set to be true by us. 856 */ 857 if (p->p_singlethread == td) 858 return (0); /* Exempt from stopping. */ 859 } 860 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 861 return (EINTR); 862 863 /* Should we goto user boundary if we didn't come from there? */ 864 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 865 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 866 return (ERESTART); 867 868 /* 869 * Ignore suspend requests for stop signals if they 870 * are deferred. 871 */ 872 if ((P_SHOULDSTOP(p) == P_STOPPED_SIG || 873 (p->p_flag & P_TOTAL_STOP) != 0) && 874 (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 = 902 thread_unsuspend_one(p->p_singlethread, p); 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 if (return_instead == 0) 922 td->td_flags &= ~TDF_BOUNDARY; 923 thread_unlock(td); 924 PROC_LOCK(p); 925 if (return_instead == 0) { 926 PROC_SLOCK(p); 927 p->p_boundary_count--; 928 PROC_SUNLOCK(p); 929 } 930 } 931 return (0); 932 } 933 934 void 935 thread_suspend_switch(struct thread *td, struct proc *p) 936 { 937 938 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 939 PROC_LOCK_ASSERT(p, MA_OWNED); 940 PROC_SLOCK_ASSERT(p, MA_OWNED); 941 /* 942 * We implement thread_suspend_one in stages here to avoid 943 * dropping the proc lock while the thread lock is owned. 944 */ 945 if (p == td->td_proc) { 946 thread_stopped(p); 947 p->p_suspcount++; 948 } 949 PROC_UNLOCK(p); 950 thread_lock(td); 951 td->td_flags &= ~TDF_NEEDSUSPCHK; 952 TD_SET_SUSPENDED(td); 953 sched_sleep(td, 0); 954 PROC_SUNLOCK(p); 955 DROP_GIANT(); 956 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 957 thread_unlock(td); 958 PICKUP_GIANT(); 959 PROC_LOCK(p); 960 PROC_SLOCK(p); 961 } 962 963 void 964 thread_suspend_one(struct thread *td) 965 { 966 struct proc *p; 967 968 p = td->td_proc; 969 PROC_SLOCK_ASSERT(p, MA_OWNED); 970 THREAD_LOCK_ASSERT(td, MA_OWNED); 971 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 972 p->p_suspcount++; 973 td->td_flags &= ~TDF_NEEDSUSPCHK; 974 TD_SET_SUSPENDED(td); 975 sched_sleep(td, 0); 976 } 977 978 int 979 thread_unsuspend_one(struct thread *td, struct proc *p) 980 { 981 982 THREAD_LOCK_ASSERT(td, MA_OWNED); 983 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 984 TD_CLR_SUSPENDED(td); 985 td->td_flags &= ~TDF_ALLPROCSUSP; 986 if (td->td_proc == p) { 987 PROC_SLOCK_ASSERT(p, MA_OWNED); 988 p->p_suspcount--; 989 } 990 return (setrunnable(td)); 991 } 992 993 /* 994 * Allow all threads blocked by single threading to continue running. 995 */ 996 void 997 thread_unsuspend(struct proc *p) 998 { 999 struct thread *td; 1000 int wakeup_swapper; 1001 1002 PROC_LOCK_ASSERT(p, MA_OWNED); 1003 PROC_SLOCK_ASSERT(p, MA_OWNED); 1004 wakeup_swapper = 0; 1005 if (!P_SHOULDSTOP(p)) { 1006 FOREACH_THREAD_IN_PROC(p, td) { 1007 thread_lock(td); 1008 if (TD_IS_SUSPENDED(td)) { 1009 wakeup_swapper |= thread_unsuspend_one(td, p); 1010 } 1011 thread_unlock(td); 1012 } 1013 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 1014 (p->p_numthreads == p->p_suspcount)) { 1015 /* 1016 * Stopping everything also did the job for the single 1017 * threading request. Now we've downgraded to single-threaded, 1018 * let it continue. 1019 */ 1020 if (p->p_singlethread->td_proc == p) { 1021 thread_lock(p->p_singlethread); 1022 wakeup_swapper = thread_unsuspend_one( 1023 p->p_singlethread, p); 1024 thread_unlock(p->p_singlethread); 1025 } 1026 } 1027 if (wakeup_swapper) 1028 kick_proc0(); 1029 } 1030 1031 /* 1032 * End the single threading mode.. 1033 */ 1034 void 1035 thread_single_end(struct proc *p, int mode) 1036 { 1037 struct thread *td; 1038 int wakeup_swapper; 1039 1040 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1041 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1042 ("invalid mode %d", mode)); 1043 PROC_LOCK_ASSERT(p, MA_OWNED); 1044 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1045 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1046 ("mode %d does not match P_TOTAL_STOP", mode)); 1047 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1048 P_TOTAL_STOP); 1049 PROC_SLOCK(p); 1050 p->p_singlethread = NULL; 1051 wakeup_swapper = 0; 1052 /* 1053 * If there are other threads they may now run, 1054 * unless of course there is a blanket 'stop order' 1055 * on the process. The single threader must be allowed 1056 * to continue however as this is a bad place to stop. 1057 */ 1058 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1059 FOREACH_THREAD_IN_PROC(p, td) { 1060 thread_lock(td); 1061 if (TD_IS_SUSPENDED(td)) { 1062 wakeup_swapper |= thread_unsuspend_one(td, p); 1063 } 1064 thread_unlock(td); 1065 } 1066 } 1067 PROC_SUNLOCK(p); 1068 if (wakeup_swapper) 1069 kick_proc0(); 1070 } 1071 1072 struct thread * 1073 thread_find(struct proc *p, lwpid_t tid) 1074 { 1075 struct thread *td; 1076 1077 PROC_LOCK_ASSERT(p, MA_OWNED); 1078 FOREACH_THREAD_IN_PROC(p, td) { 1079 if (td->td_tid == tid) 1080 break; 1081 } 1082 return (td); 1083 } 1084 1085 /* Locate a thread by number; return with proc lock held. */ 1086 struct thread * 1087 tdfind(lwpid_t tid, pid_t pid) 1088 { 1089 #define RUN_THRESH 16 1090 struct thread *td; 1091 int run = 0; 1092 1093 rw_rlock(&tidhash_lock); 1094 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1095 if (td->td_tid == tid) { 1096 if (pid != -1 && td->td_proc->p_pid != pid) { 1097 td = NULL; 1098 break; 1099 } 1100 PROC_LOCK(td->td_proc); 1101 if (td->td_proc->p_state == PRS_NEW) { 1102 PROC_UNLOCK(td->td_proc); 1103 td = NULL; 1104 break; 1105 } 1106 if (run > RUN_THRESH) { 1107 if (rw_try_upgrade(&tidhash_lock)) { 1108 LIST_REMOVE(td, td_hash); 1109 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1110 td, td_hash); 1111 rw_wunlock(&tidhash_lock); 1112 return (td); 1113 } 1114 } 1115 break; 1116 } 1117 run++; 1118 } 1119 rw_runlock(&tidhash_lock); 1120 return (td); 1121 } 1122 1123 void 1124 tidhash_add(struct thread *td) 1125 { 1126 rw_wlock(&tidhash_lock); 1127 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1128 rw_wunlock(&tidhash_lock); 1129 } 1130 1131 void 1132 tidhash_remove(struct thread *td) 1133 { 1134 rw_wlock(&tidhash_lock); 1135 LIST_REMOVE(td, td_hash); 1136 rw_wunlock(&tidhash_lock); 1137 } 1138