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/resourcevar.h> 42 #include <sys/smp.h> 43 #include <sys/sysctl.h> 44 #include <sys/sched.h> 45 #include <sys/sleepqueue.h> 46 #include <sys/selinfo.h> 47 #include <sys/turnstile.h> 48 #include <sys/ktr.h> 49 #include <sys/umtx.h> 50 #include <sys/cpuset.h> 51 #ifdef HWPMC_HOOKS 52 #include <sys/pmckern.h> 53 #endif 54 55 #include <security/audit/audit.h> 56 57 #include <vm/vm.h> 58 #include <vm/vm_extern.h> 59 #include <vm/uma.h> 60 #include <sys/eventhandler.h> 61 62 /* 63 * thread related storage. 64 */ 65 static uma_zone_t thread_zone; 66 67 SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation"); 68 69 int max_threads_per_proc = 1500; 70 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW, 71 &max_threads_per_proc, 0, "Limit on threads per proc"); 72 73 int max_threads_hits; 74 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD, 75 &max_threads_hits, 0, ""); 76 77 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 78 static struct mtx zombie_lock; 79 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 80 81 static void thread_zombie(struct thread *); 82 83 struct mtx tid_lock; 84 static struct unrhdr *tid_unrhdr; 85 86 /* 87 * Prepare a thread for use. 88 */ 89 static int 90 thread_ctor(void *mem, int size, void *arg, int flags) 91 { 92 struct thread *td; 93 94 td = (struct thread *)mem; 95 td->td_state = TDS_INACTIVE; 96 td->td_oncpu = NOCPU; 97 98 td->td_tid = alloc_unr(tid_unrhdr); 99 td->td_syscalls = 0; 100 101 /* 102 * Note that td_critnest begins life as 1 because the thread is not 103 * running and is thereby implicitly waiting to be on the receiving 104 * end of a context switch. 105 */ 106 td->td_critnest = 1; 107 EVENTHANDLER_INVOKE(thread_ctor, td); 108 #ifdef AUDIT 109 audit_thread_alloc(td); 110 #endif 111 umtx_thread_alloc(td); 112 return (0); 113 } 114 115 /* 116 * Reclaim a thread after use. 117 */ 118 static void 119 thread_dtor(void *mem, int size, void *arg) 120 { 121 struct thread *td; 122 123 td = (struct thread *)mem; 124 125 #ifdef INVARIANTS 126 /* Verify that this thread is in a safe state to free. */ 127 switch (td->td_state) { 128 case TDS_INHIBITED: 129 case TDS_RUNNING: 130 case TDS_CAN_RUN: 131 case TDS_RUNQ: 132 /* 133 * We must never unlink a thread that is in one of 134 * these states, because it is currently active. 135 */ 136 panic("bad state for thread unlinking"); 137 /* NOTREACHED */ 138 case TDS_INACTIVE: 139 break; 140 default: 141 panic("bad thread state"); 142 /* NOTREACHED */ 143 } 144 #endif 145 #ifdef AUDIT 146 audit_thread_free(td); 147 #endif 148 /* Free all OSD associated to this thread. */ 149 osd_thread_exit(td); 150 151 EVENTHANDLER_INVOKE(thread_dtor, td); 152 free_unr(tid_unrhdr, td->td_tid); 153 } 154 155 /* 156 * Initialize type-stable parts of a thread (when newly created). 157 */ 158 static int 159 thread_init(void *mem, int size, int flags) 160 { 161 struct thread *td; 162 163 td = (struct thread *)mem; 164 165 td->td_sleepqueue = sleepq_alloc(); 166 td->td_turnstile = turnstile_alloc(); 167 EVENTHANDLER_INVOKE(thread_init, td); 168 td->td_sched = (struct td_sched *)&td[1]; 169 umtx_thread_init(td); 170 td->td_kstack = 0; 171 return (0); 172 } 173 174 /* 175 * Tear down type-stable parts of a thread (just before being discarded). 176 */ 177 static void 178 thread_fini(void *mem, int size) 179 { 180 struct thread *td; 181 182 td = (struct thread *)mem; 183 EVENTHANDLER_INVOKE(thread_fini, td); 184 turnstile_free(td->td_turnstile); 185 sleepq_free(td->td_sleepqueue); 186 umtx_thread_fini(td); 187 seltdfini(td); 188 } 189 190 /* 191 * For a newly created process, 192 * link up all the structures and its initial threads etc. 193 * called from: 194 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 195 * proc_dtor() (should go away) 196 * proc_init() 197 */ 198 void 199 proc_linkup0(struct proc *p, struct thread *td) 200 { 201 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 202 proc_linkup(p, td); 203 } 204 205 void 206 proc_linkup(struct proc *p, struct thread *td) 207 { 208 209 sigqueue_init(&p->p_sigqueue, p); 210 p->p_ksi = ksiginfo_alloc(1); 211 if (p->p_ksi != NULL) { 212 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 213 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 214 } 215 LIST_INIT(&p->p_mqnotifier); 216 p->p_numthreads = 0; 217 thread_link(td, p); 218 } 219 220 /* 221 * Initialize global thread allocation resources. 222 */ 223 void 224 threadinit(void) 225 { 226 227 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 228 /* leave one number for thread0 */ 229 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 230 231 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 232 thread_ctor, thread_dtor, thread_init, thread_fini, 233 16 - 1, 0); 234 } 235 236 /* 237 * Place an unused thread on the zombie list. 238 * Use the slpq as that must be unused by now. 239 */ 240 void 241 thread_zombie(struct thread *td) 242 { 243 mtx_lock_spin(&zombie_lock); 244 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 245 mtx_unlock_spin(&zombie_lock); 246 } 247 248 /* 249 * Release a thread that has exited after cpu_throw(). 250 */ 251 void 252 thread_stash(struct thread *td) 253 { 254 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 255 thread_zombie(td); 256 } 257 258 /* 259 * Reap zombie resources. 260 */ 261 void 262 thread_reap(void) 263 { 264 struct thread *td_first, *td_next; 265 266 /* 267 * Don't even bother to lock if none at this instant, 268 * we really don't care about the next instant.. 269 */ 270 if (!TAILQ_EMPTY(&zombie_threads)) { 271 mtx_lock_spin(&zombie_lock); 272 td_first = TAILQ_FIRST(&zombie_threads); 273 if (td_first) 274 TAILQ_INIT(&zombie_threads); 275 mtx_unlock_spin(&zombie_lock); 276 while (td_first) { 277 td_next = TAILQ_NEXT(td_first, td_slpq); 278 if (td_first->td_ucred) 279 crfree(td_first->td_ucred); 280 thread_free(td_first); 281 td_first = td_next; 282 } 283 } 284 } 285 286 /* 287 * Allocate a thread. 288 */ 289 struct thread * 290 thread_alloc(int pages) 291 { 292 struct thread *td; 293 294 thread_reap(); /* check if any zombies to get */ 295 296 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 297 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 298 if (!vm_thread_new(td, pages)) { 299 uma_zfree(thread_zone, td); 300 return (NULL); 301 } 302 cpu_thread_alloc(td); 303 return (td); 304 } 305 306 int 307 thread_alloc_stack(struct thread *td, int pages) 308 { 309 310 KASSERT(td->td_kstack == 0, 311 ("thread_alloc_stack called on a thread with kstack")); 312 if (!vm_thread_new(td, pages)) 313 return (0); 314 cpu_thread_alloc(td); 315 return (1); 316 } 317 318 /* 319 * Deallocate a thread. 320 */ 321 void 322 thread_free(struct thread *td) 323 { 324 325 lock_profile_thread_exit(td); 326 if (td->td_cpuset) 327 cpuset_rel(td->td_cpuset); 328 td->td_cpuset = NULL; 329 cpu_thread_free(td); 330 if (td->td_kstack != 0) 331 vm_thread_dispose(td); 332 uma_zfree(thread_zone, td); 333 } 334 335 /* 336 * Discard the current thread and exit from its context. 337 * Always called with scheduler locked. 338 * 339 * Because we can't free a thread while we're operating under its context, 340 * push the current thread into our CPU's deadthread holder. This means 341 * we needn't worry about someone else grabbing our context before we 342 * do a cpu_throw(). 343 */ 344 void 345 thread_exit(void) 346 { 347 uint64_t new_switchtime; 348 struct thread *td; 349 struct thread *td2; 350 struct proc *p; 351 int wakeup_swapper; 352 353 td = curthread; 354 p = td->td_proc; 355 356 PROC_SLOCK_ASSERT(p, MA_OWNED); 357 mtx_assert(&Giant, MA_NOTOWNED); 358 359 PROC_LOCK_ASSERT(p, MA_OWNED); 360 KASSERT(p != NULL, ("thread exiting without a process")); 361 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 362 (long)p->p_pid, td->td_name); 363 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 364 365 #ifdef AUDIT 366 AUDIT_SYSCALL_EXIT(0, td); 367 #endif 368 umtx_thread_exit(td); 369 /* 370 * drop FPU & debug register state storage, or any other 371 * architecture specific resources that 372 * would not be on a new untouched process. 373 */ 374 cpu_thread_exit(td); /* XXXSMP */ 375 376 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 377 new_switchtime = cpu_ticks(); 378 p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime)); 379 PCPU_SET(switchtime, new_switchtime); 380 PCPU_SET(switchticks, ticks); 381 PCPU_INC(cnt.v_swtch); 382 /* Save our resource usage in our process. */ 383 td->td_ru.ru_nvcsw++; 384 rucollect(&p->p_ru, &td->td_ru); 385 /* 386 * The last thread is left attached to the process 387 * So that the whole bundle gets recycled. Skip 388 * all this stuff if we never had threads. 389 * EXIT clears all sign of other threads when 390 * it goes to single threading, so the last thread always 391 * takes the short path. 392 */ 393 if (p->p_flag & P_HADTHREADS) { 394 if (p->p_numthreads > 1) { 395 thread_unlink(td); 396 td2 = FIRST_THREAD_IN_PROC(p); 397 sched_exit_thread(td2, td); 398 399 /* 400 * The test below is NOT true if we are the 401 * sole exiting thread. P_STOPPED_SNGL is unset 402 * in exit1() after it is the only survivor. 403 */ 404 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 405 if (p->p_numthreads == p->p_suspcount) { 406 thread_lock(p->p_singlethread); 407 wakeup_swapper = thread_unsuspend_one( 408 p->p_singlethread); 409 thread_unlock(p->p_singlethread); 410 if (wakeup_swapper) 411 kick_proc0(); 412 } 413 } 414 415 atomic_add_int(&td->td_proc->p_exitthreads, 1); 416 PCPU_SET(deadthread, td); 417 } else { 418 /* 419 * The last thread is exiting.. but not through exit() 420 */ 421 panic ("thread_exit: Last thread exiting on its own"); 422 } 423 } 424 #ifdef HWPMC_HOOKS 425 /* 426 * If this thread is part of a process that is being tracked by hwpmc(4), 427 * inform the module of the thread's impending exit. 428 */ 429 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 430 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 431 #endif 432 PROC_UNLOCK(p); 433 thread_lock(td); 434 /* Save our tick information with both the thread and proc locked */ 435 ruxagg(&p->p_rux, td); 436 PROC_SUNLOCK(p); 437 td->td_state = TDS_INACTIVE; 438 #ifdef WITNESS 439 witness_thread_exit(td); 440 #endif 441 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 442 sched_throw(td); 443 panic("I'm a teapot!"); 444 /* NOTREACHED */ 445 } 446 447 /* 448 * Do any thread specific cleanups that may be needed in wait() 449 * called with Giant, proc and schedlock not held. 450 */ 451 void 452 thread_wait(struct proc *p) 453 { 454 struct thread *td; 455 456 mtx_assert(&Giant, MA_NOTOWNED); 457 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 458 td = FIRST_THREAD_IN_PROC(p); 459 /* Lock the last thread so we spin until it exits cpu_throw(). */ 460 thread_lock(td); 461 thread_unlock(td); 462 /* Wait for any remaining threads to exit cpu_throw(). */ 463 while (p->p_exitthreads) 464 sched_relinquish(curthread); 465 lock_profile_thread_exit(td); 466 cpuset_rel(td->td_cpuset); 467 td->td_cpuset = NULL; 468 cpu_thread_clean(td); 469 crfree(td->td_ucred); 470 thread_reap(); /* check for zombie threads etc. */ 471 } 472 473 /* 474 * Link a thread to a process. 475 * set up anything that needs to be initialized for it to 476 * be used by the process. 477 */ 478 void 479 thread_link(struct thread *td, struct proc *p) 480 { 481 482 /* 483 * XXX This can't be enabled because it's called for proc0 before 484 * its lock has been created. 485 * PROC_LOCK_ASSERT(p, MA_OWNED); 486 */ 487 td->td_state = TDS_INACTIVE; 488 td->td_proc = p; 489 td->td_flags = TDF_INMEM; 490 491 LIST_INIT(&td->td_contested); 492 LIST_INIT(&td->td_lprof[0]); 493 LIST_INIT(&td->td_lprof[1]); 494 sigqueue_init(&td->td_sigqueue, p); 495 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 496 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 497 p->p_numthreads++; 498 } 499 500 /* 501 * Convert a process with one thread to an unthreaded process. 502 */ 503 void 504 thread_unthread(struct thread *td) 505 { 506 struct proc *p = td->td_proc; 507 508 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 509 p->p_flag &= ~P_HADTHREADS; 510 } 511 512 /* 513 * Called from: 514 * thread_exit() 515 */ 516 void 517 thread_unlink(struct thread *td) 518 { 519 struct proc *p = td->td_proc; 520 521 PROC_LOCK_ASSERT(p, MA_OWNED); 522 TAILQ_REMOVE(&p->p_threads, td, td_plist); 523 p->p_numthreads--; 524 /* could clear a few other things here */ 525 /* Must NOT clear links to proc! */ 526 } 527 528 static int 529 calc_remaining(struct proc *p, int mode) 530 { 531 int remaining; 532 533 if (mode == SINGLE_EXIT) 534 remaining = p->p_numthreads; 535 else if (mode == SINGLE_BOUNDARY) 536 remaining = p->p_numthreads - p->p_boundary_count; 537 else if (mode == SINGLE_NO_EXIT) 538 remaining = p->p_numthreads - p->p_suspcount; 539 else 540 panic("calc_remaining: wrong mode %d", mode); 541 return (remaining); 542 } 543 544 /* 545 * Enforce single-threading. 546 * 547 * Returns 1 if the caller must abort (another thread is waiting to 548 * exit the process or similar). Process is locked! 549 * Returns 0 when you are successfully the only thread running. 550 * A process has successfully single threaded in the suspend mode when 551 * There are no threads in user mode. Threads in the kernel must be 552 * allowed to continue until they get to the user boundary. They may even 553 * copy out their return values and data before suspending. They may however be 554 * accelerated in reaching the user boundary as we will wake up 555 * any sleeping threads that are interruptable. (PCATCH). 556 */ 557 int 558 thread_single(int mode) 559 { 560 struct thread *td; 561 struct thread *td2; 562 struct proc *p; 563 int remaining, wakeup_swapper; 564 565 td = curthread; 566 p = td->td_proc; 567 mtx_assert(&Giant, MA_NOTOWNED); 568 PROC_LOCK_ASSERT(p, MA_OWNED); 569 KASSERT((td != NULL), ("curthread is NULL")); 570 571 if ((p->p_flag & P_HADTHREADS) == 0) 572 return (0); 573 574 /* Is someone already single threading? */ 575 if (p->p_singlethread != NULL && p->p_singlethread != td) 576 return (1); 577 578 if (mode == SINGLE_EXIT) { 579 p->p_flag |= P_SINGLE_EXIT; 580 p->p_flag &= ~P_SINGLE_BOUNDARY; 581 } else { 582 p->p_flag &= ~P_SINGLE_EXIT; 583 if (mode == SINGLE_BOUNDARY) 584 p->p_flag |= P_SINGLE_BOUNDARY; 585 else 586 p->p_flag &= ~P_SINGLE_BOUNDARY; 587 } 588 p->p_flag |= P_STOPPED_SINGLE; 589 PROC_SLOCK(p); 590 p->p_singlethread = td; 591 remaining = calc_remaining(p, mode); 592 while (remaining != 1) { 593 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 594 goto stopme; 595 wakeup_swapper = 0; 596 FOREACH_THREAD_IN_PROC(p, td2) { 597 if (td2 == td) 598 continue; 599 thread_lock(td2); 600 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 601 if (TD_IS_INHIBITED(td2)) { 602 switch (mode) { 603 case SINGLE_EXIT: 604 if (TD_IS_SUSPENDED(td2)) 605 wakeup_swapper |= 606 thread_unsuspend_one(td2); 607 if (TD_ON_SLEEPQ(td2) && 608 (td2->td_flags & TDF_SINTR)) 609 wakeup_swapper |= 610 sleepq_abort(td2, EINTR); 611 break; 612 case SINGLE_BOUNDARY: 613 if (TD_IS_SUSPENDED(td2) && 614 !(td2->td_flags & TDF_BOUNDARY)) 615 wakeup_swapper |= 616 thread_unsuspend_one(td2); 617 if (TD_ON_SLEEPQ(td2) && 618 (td2->td_flags & TDF_SINTR)) 619 wakeup_swapper |= 620 sleepq_abort(td2, ERESTART); 621 break; 622 case SINGLE_NO_EXIT: 623 if (TD_IS_SUSPENDED(td2) && 624 !(td2->td_flags & TDF_BOUNDARY)) 625 wakeup_swapper |= 626 thread_unsuspend_one(td2); 627 if (TD_ON_SLEEPQ(td2) && 628 (td2->td_flags & TDF_SINTR)) 629 wakeup_swapper |= 630 sleepq_abort(td2, ERESTART); 631 break; 632 default: 633 break; 634 } 635 } 636 #ifdef SMP 637 else if (TD_IS_RUNNING(td2) && td != td2) { 638 forward_signal(td2); 639 } 640 #endif 641 thread_unlock(td2); 642 } 643 if (wakeup_swapper) 644 kick_proc0(); 645 remaining = calc_remaining(p, mode); 646 647 /* 648 * Maybe we suspended some threads.. was it enough? 649 */ 650 if (remaining == 1) 651 break; 652 653 stopme: 654 /* 655 * Wake us up when everyone else has suspended. 656 * In the mean time we suspend as well. 657 */ 658 thread_suspend_switch(td); 659 remaining = calc_remaining(p, mode); 660 } 661 if (mode == SINGLE_EXIT) { 662 /* 663 * We have gotten rid of all the other threads and we 664 * are about to either exit or exec. In either case, 665 * we try our utmost to revert to being a non-threaded 666 * process. 667 */ 668 p->p_singlethread = NULL; 669 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 670 thread_unthread(td); 671 } 672 PROC_SUNLOCK(p); 673 return (0); 674 } 675 676 /* 677 * Called in from locations that can safely check to see 678 * whether we have to suspend or at least throttle for a 679 * single-thread event (e.g. fork). 680 * 681 * Such locations include userret(). 682 * If the "return_instead" argument is non zero, the thread must be able to 683 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 684 * 685 * The 'return_instead' argument tells the function if it may do a 686 * thread_exit() or suspend, or whether the caller must abort and back 687 * out instead. 688 * 689 * If the thread that set the single_threading request has set the 690 * P_SINGLE_EXIT bit in the process flags then this call will never return 691 * if 'return_instead' is false, but will exit. 692 * 693 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 694 *---------------+--------------------+--------------------- 695 * 0 | returns 0 | returns 0 or 1 696 * | when ST ends | immediatly 697 *---------------+--------------------+--------------------- 698 * 1 | thread exits | returns 1 699 * | | immediatly 700 * 0 = thread_exit() or suspension ok, 701 * other = return error instead of stopping the thread. 702 * 703 * While a full suspension is under effect, even a single threading 704 * thread would be suspended if it made this call (but it shouldn't). 705 * This call should only be made from places where 706 * thread_exit() would be safe as that may be the outcome unless 707 * return_instead is set. 708 */ 709 int 710 thread_suspend_check(int return_instead) 711 { 712 struct thread *td; 713 struct proc *p; 714 int wakeup_swapper; 715 716 td = curthread; 717 p = td->td_proc; 718 mtx_assert(&Giant, MA_NOTOWNED); 719 PROC_LOCK_ASSERT(p, MA_OWNED); 720 while (P_SHOULDSTOP(p) || 721 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) { 722 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 723 KASSERT(p->p_singlethread != NULL, 724 ("singlethread not set")); 725 /* 726 * The only suspension in action is a 727 * single-threading. Single threader need not stop. 728 * XXX Should be safe to access unlocked 729 * as it can only be set to be true by us. 730 */ 731 if (p->p_singlethread == td) 732 return (0); /* Exempt from stopping. */ 733 } 734 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 735 return (EINTR); 736 737 /* Should we goto user boundary if we didn't come from there? */ 738 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 739 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 740 return (ERESTART); 741 742 /* If thread will exit, flush its pending signals */ 743 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 744 sigqueue_flush(&td->td_sigqueue); 745 746 PROC_SLOCK(p); 747 thread_stopped(p); 748 /* 749 * If the process is waiting for us to exit, 750 * this thread should just suicide. 751 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 752 */ 753 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 754 thread_exit(); 755 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 756 if (p->p_numthreads == p->p_suspcount + 1) { 757 thread_lock(p->p_singlethread); 758 wakeup_swapper = 759 thread_unsuspend_one(p->p_singlethread); 760 thread_unlock(p->p_singlethread); 761 if (wakeup_swapper) 762 kick_proc0(); 763 } 764 } 765 PROC_UNLOCK(p); 766 thread_lock(td); 767 /* 768 * When a thread suspends, it just 769 * gets taken off all queues. 770 */ 771 thread_suspend_one(td); 772 if (return_instead == 0) { 773 p->p_boundary_count++; 774 td->td_flags |= TDF_BOUNDARY; 775 } 776 PROC_SUNLOCK(p); 777 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 778 if (return_instead == 0) 779 td->td_flags &= ~TDF_BOUNDARY; 780 thread_unlock(td); 781 PROC_LOCK(p); 782 if (return_instead == 0) 783 p->p_boundary_count--; 784 } 785 return (0); 786 } 787 788 void 789 thread_suspend_switch(struct thread *td) 790 { 791 struct proc *p; 792 793 p = td->td_proc; 794 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 795 PROC_LOCK_ASSERT(p, MA_OWNED); 796 PROC_SLOCK_ASSERT(p, MA_OWNED); 797 /* 798 * We implement thread_suspend_one in stages here to avoid 799 * dropping the proc lock while the thread lock is owned. 800 */ 801 thread_stopped(p); 802 p->p_suspcount++; 803 PROC_UNLOCK(p); 804 thread_lock(td); 805 td->td_flags &= ~TDF_NEEDSUSPCHK; 806 TD_SET_SUSPENDED(td); 807 sched_sleep(td, 0); 808 PROC_SUNLOCK(p); 809 DROP_GIANT(); 810 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 811 thread_unlock(td); 812 PICKUP_GIANT(); 813 PROC_LOCK(p); 814 PROC_SLOCK(p); 815 } 816 817 void 818 thread_suspend_one(struct thread *td) 819 { 820 struct proc *p = td->td_proc; 821 822 PROC_SLOCK_ASSERT(p, MA_OWNED); 823 THREAD_LOCK_ASSERT(td, MA_OWNED); 824 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 825 p->p_suspcount++; 826 td->td_flags &= ~TDF_NEEDSUSPCHK; 827 TD_SET_SUSPENDED(td); 828 sched_sleep(td, 0); 829 } 830 831 int 832 thread_unsuspend_one(struct thread *td) 833 { 834 struct proc *p = td->td_proc; 835 836 PROC_SLOCK_ASSERT(p, MA_OWNED); 837 THREAD_LOCK_ASSERT(td, MA_OWNED); 838 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 839 TD_CLR_SUSPENDED(td); 840 p->p_suspcount--; 841 return (setrunnable(td)); 842 } 843 844 /* 845 * Allow all threads blocked by single threading to continue running. 846 */ 847 void 848 thread_unsuspend(struct proc *p) 849 { 850 struct thread *td; 851 int wakeup_swapper; 852 853 PROC_LOCK_ASSERT(p, MA_OWNED); 854 PROC_SLOCK_ASSERT(p, MA_OWNED); 855 wakeup_swapper = 0; 856 if (!P_SHOULDSTOP(p)) { 857 FOREACH_THREAD_IN_PROC(p, td) { 858 thread_lock(td); 859 if (TD_IS_SUSPENDED(td)) { 860 wakeup_swapper |= thread_unsuspend_one(td); 861 } 862 thread_unlock(td); 863 } 864 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 865 (p->p_numthreads == p->p_suspcount)) { 866 /* 867 * Stopping everything also did the job for the single 868 * threading request. Now we've downgraded to single-threaded, 869 * let it continue. 870 */ 871 thread_lock(p->p_singlethread); 872 wakeup_swapper = thread_unsuspend_one(p->p_singlethread); 873 thread_unlock(p->p_singlethread); 874 } 875 if (wakeup_swapper) 876 kick_proc0(); 877 } 878 879 /* 880 * End the single threading mode.. 881 */ 882 void 883 thread_single_end(void) 884 { 885 struct thread *td; 886 struct proc *p; 887 int wakeup_swapper; 888 889 td = curthread; 890 p = td->td_proc; 891 PROC_LOCK_ASSERT(p, MA_OWNED); 892 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 893 PROC_SLOCK(p); 894 p->p_singlethread = NULL; 895 wakeup_swapper = 0; 896 /* 897 * If there are other threads they may now run, 898 * unless of course there is a blanket 'stop order' 899 * on the process. The single threader must be allowed 900 * to continue however as this is a bad place to stop. 901 */ 902 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 903 FOREACH_THREAD_IN_PROC(p, td) { 904 thread_lock(td); 905 if (TD_IS_SUSPENDED(td)) { 906 wakeup_swapper |= thread_unsuspend_one(td); 907 } 908 thread_unlock(td); 909 } 910 } 911 PROC_SUNLOCK(p); 912 if (wakeup_swapper) 913 kick_proc0(); 914 } 915 916 struct thread * 917 thread_find(struct proc *p, lwpid_t tid) 918 { 919 struct thread *td; 920 921 PROC_LOCK_ASSERT(p, MA_OWNED); 922 FOREACH_THREAD_IN_PROC(p, td) { 923 if (td->td_tid == tid) 924 break; 925 } 926 return (td); 927 } 928