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_SINGLE 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 ruxagg(p, td); 434 thread_lock(td); 435 PROC_SUNLOCK(p); 436 td->td_state = TDS_INACTIVE; 437 #ifdef WITNESS 438 witness_thread_exit(td); 439 #endif 440 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 441 sched_throw(td); 442 panic("I'm a teapot!"); 443 /* NOTREACHED */ 444 } 445 446 /* 447 * Do any thread specific cleanups that may be needed in wait() 448 * called with Giant, proc and schedlock not held. 449 */ 450 void 451 thread_wait(struct proc *p) 452 { 453 struct thread *td; 454 455 mtx_assert(&Giant, MA_NOTOWNED); 456 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 457 td = FIRST_THREAD_IN_PROC(p); 458 /* Lock the last thread so we spin until it exits cpu_throw(). */ 459 thread_lock(td); 460 thread_unlock(td); 461 /* Wait for any remaining threads to exit cpu_throw(). */ 462 while (p->p_exitthreads) 463 sched_relinquish(curthread); 464 lock_profile_thread_exit(td); 465 cpuset_rel(td->td_cpuset); 466 td->td_cpuset = NULL; 467 cpu_thread_clean(td); 468 crfree(td->td_ucred); 469 thread_reap(); /* check for zombie threads etc. */ 470 } 471 472 /* 473 * Link a thread to a process. 474 * set up anything that needs to be initialized for it to 475 * be used by the process. 476 */ 477 void 478 thread_link(struct thread *td, struct proc *p) 479 { 480 481 /* 482 * XXX This can't be enabled because it's called for proc0 before 483 * its lock has been created. 484 * PROC_LOCK_ASSERT(p, MA_OWNED); 485 */ 486 td->td_state = TDS_INACTIVE; 487 td->td_proc = p; 488 td->td_flags = TDF_INMEM; 489 490 LIST_INIT(&td->td_contested); 491 LIST_INIT(&td->td_lprof[0]); 492 LIST_INIT(&td->td_lprof[1]); 493 sigqueue_init(&td->td_sigqueue, p); 494 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 495 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 496 p->p_numthreads++; 497 } 498 499 /* 500 * Convert a process with one thread to an unthreaded process. 501 */ 502 void 503 thread_unthread(struct thread *td) 504 { 505 struct proc *p = td->td_proc; 506 507 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 508 p->p_flag &= ~P_HADTHREADS; 509 } 510 511 /* 512 * Called from: 513 * thread_exit() 514 */ 515 void 516 thread_unlink(struct thread *td) 517 { 518 struct proc *p = td->td_proc; 519 520 PROC_LOCK_ASSERT(p, MA_OWNED); 521 TAILQ_REMOVE(&p->p_threads, td, td_plist); 522 p->p_numthreads--; 523 /* could clear a few other things here */ 524 /* Must NOT clear links to proc! */ 525 } 526 527 static int 528 calc_remaining(struct proc *p, int mode) 529 { 530 int remaining; 531 532 if (mode == SINGLE_EXIT) 533 remaining = p->p_numthreads; 534 else if (mode == SINGLE_BOUNDARY) 535 remaining = p->p_numthreads - p->p_boundary_count; 536 else if (mode == SINGLE_NO_EXIT) 537 remaining = p->p_numthreads - p->p_suspcount; 538 else 539 panic("calc_remaining: wrong mode %d", mode); 540 return (remaining); 541 } 542 543 /* 544 * Enforce single-threading. 545 * 546 * Returns 1 if the caller must abort (another thread is waiting to 547 * exit the process or similar). Process is locked! 548 * Returns 0 when you are successfully the only thread running. 549 * A process has successfully single threaded in the suspend mode when 550 * There are no threads in user mode. Threads in the kernel must be 551 * allowed to continue until they get to the user boundary. They may even 552 * copy out their return values and data before suspending. They may however be 553 * accelerated in reaching the user boundary as we will wake up 554 * any sleeping threads that are interruptable. (PCATCH). 555 */ 556 int 557 thread_single(int mode) 558 { 559 struct thread *td; 560 struct thread *td2; 561 struct proc *p; 562 int remaining, wakeup_swapper; 563 564 td = curthread; 565 p = td->td_proc; 566 mtx_assert(&Giant, MA_NOTOWNED); 567 PROC_LOCK_ASSERT(p, MA_OWNED); 568 KASSERT((td != NULL), ("curthread is NULL")); 569 570 if ((p->p_flag & P_HADTHREADS) == 0) 571 return (0); 572 573 /* Is someone already single threading? */ 574 if (p->p_singlethread != NULL && p->p_singlethread != td) 575 return (1); 576 577 if (mode == SINGLE_EXIT) { 578 p->p_flag |= P_SINGLE_EXIT; 579 p->p_flag &= ~P_SINGLE_BOUNDARY; 580 } else { 581 p->p_flag &= ~P_SINGLE_EXIT; 582 if (mode == SINGLE_BOUNDARY) 583 p->p_flag |= P_SINGLE_BOUNDARY; 584 else 585 p->p_flag &= ~P_SINGLE_BOUNDARY; 586 } 587 p->p_flag |= P_STOPPED_SINGLE; 588 PROC_SLOCK(p); 589 p->p_singlethread = td; 590 remaining = calc_remaining(p, mode); 591 while (remaining != 1) { 592 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 593 goto stopme; 594 wakeup_swapper = 0; 595 FOREACH_THREAD_IN_PROC(p, td2) { 596 if (td2 == td) 597 continue; 598 thread_lock(td2); 599 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 600 if (TD_IS_INHIBITED(td2)) { 601 switch (mode) { 602 case SINGLE_EXIT: 603 if (TD_IS_SUSPENDED(td2)) 604 wakeup_swapper |= 605 thread_unsuspend_one(td2); 606 if (TD_ON_SLEEPQ(td2) && 607 (td2->td_flags & TDF_SINTR)) 608 wakeup_swapper |= 609 sleepq_abort(td2, EINTR); 610 break; 611 case SINGLE_BOUNDARY: 612 if (TD_IS_SUSPENDED(td2) && 613 !(td2->td_flags & TDF_BOUNDARY)) 614 wakeup_swapper |= 615 thread_unsuspend_one(td2); 616 if (TD_ON_SLEEPQ(td2) && 617 (td2->td_flags & TDF_SINTR)) 618 wakeup_swapper |= 619 sleepq_abort(td2, ERESTART); 620 break; 621 case SINGLE_NO_EXIT: 622 if (TD_IS_SUSPENDED(td2) && 623 !(td2->td_flags & TDF_BOUNDARY)) 624 wakeup_swapper |= 625 thread_unsuspend_one(td2); 626 if (TD_ON_SLEEPQ(td2) && 627 (td2->td_flags & TDF_SINTR)) 628 wakeup_swapper |= 629 sleepq_abort(td2, ERESTART); 630 break; 631 default: 632 break; 633 } 634 } 635 #ifdef SMP 636 else if (TD_IS_RUNNING(td2) && td != td2) { 637 forward_signal(td2); 638 } 639 #endif 640 thread_unlock(td2); 641 } 642 if (wakeup_swapper) 643 kick_proc0(); 644 remaining = calc_remaining(p, mode); 645 646 /* 647 * Maybe we suspended some threads.. was it enough? 648 */ 649 if (remaining == 1) 650 break; 651 652 stopme: 653 /* 654 * Wake us up when everyone else has suspended. 655 * In the mean time we suspend as well. 656 */ 657 thread_suspend_switch(td); 658 remaining = calc_remaining(p, mode); 659 } 660 if (mode == SINGLE_EXIT) { 661 /* 662 * We have gotten rid of all the other threads and we 663 * are about to either exit or exec. In either case, 664 * we try our utmost to revert to being a non-threaded 665 * process. 666 */ 667 p->p_singlethread = NULL; 668 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 669 thread_unthread(td); 670 } 671 PROC_SUNLOCK(p); 672 return (0); 673 } 674 675 /* 676 * Called in from locations that can safely check to see 677 * whether we have to suspend or at least throttle for a 678 * single-thread event (e.g. fork). 679 * 680 * Such locations include userret(). 681 * If the "return_instead" argument is non zero, the thread must be able to 682 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 683 * 684 * The 'return_instead' argument tells the function if it may do a 685 * thread_exit() or suspend, or whether the caller must abort and back 686 * out instead. 687 * 688 * If the thread that set the single_threading request has set the 689 * P_SINGLE_EXIT bit in the process flags then this call will never return 690 * if 'return_instead' is false, but will exit. 691 * 692 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 693 *---------------+--------------------+--------------------- 694 * 0 | returns 0 | returns 0 or 1 695 * | when ST ends | immediatly 696 *---------------+--------------------+--------------------- 697 * 1 | thread exits | returns 1 698 * | | immediatly 699 * 0 = thread_exit() or suspension ok, 700 * other = return error instead of stopping the thread. 701 * 702 * While a full suspension is under effect, even a single threading 703 * thread would be suspended if it made this call (but it shouldn't). 704 * This call should only be made from places where 705 * thread_exit() would be safe as that may be the outcome unless 706 * return_instead is set. 707 */ 708 int 709 thread_suspend_check(int return_instead) 710 { 711 struct thread *td; 712 struct proc *p; 713 int wakeup_swapper; 714 715 td = curthread; 716 p = td->td_proc; 717 mtx_assert(&Giant, MA_NOTOWNED); 718 PROC_LOCK_ASSERT(p, MA_OWNED); 719 while (P_SHOULDSTOP(p) || 720 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) { 721 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 722 KASSERT(p->p_singlethread != NULL, 723 ("singlethread not set")); 724 /* 725 * The only suspension in action is a 726 * single-threading. Single threader need not stop. 727 * XXX Should be safe to access unlocked 728 * as it can only be set to be true by us. 729 */ 730 if (p->p_singlethread == td) 731 return (0); /* Exempt from stopping. */ 732 } 733 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 734 return (EINTR); 735 736 /* Should we goto user boundary if we didn't come from there? */ 737 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 738 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 739 return (ERESTART); 740 741 /* If thread will exit, flush its pending signals */ 742 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 743 sigqueue_flush(&td->td_sigqueue); 744 745 PROC_SLOCK(p); 746 thread_stopped(p); 747 /* 748 * If the process is waiting for us to exit, 749 * this thread should just suicide. 750 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 751 */ 752 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 753 thread_exit(); 754 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 755 if (p->p_numthreads == p->p_suspcount + 1) { 756 thread_lock(p->p_singlethread); 757 wakeup_swapper = 758 thread_unsuspend_one(p->p_singlethread); 759 thread_unlock(p->p_singlethread); 760 if (wakeup_swapper) 761 kick_proc0(); 762 } 763 } 764 PROC_UNLOCK(p); 765 thread_lock(td); 766 /* 767 * When a thread suspends, it just 768 * gets taken off all queues. 769 */ 770 thread_suspend_one(td); 771 if (return_instead == 0) { 772 p->p_boundary_count++; 773 td->td_flags |= TDF_BOUNDARY; 774 } 775 PROC_SUNLOCK(p); 776 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 777 if (return_instead == 0) 778 td->td_flags &= ~TDF_BOUNDARY; 779 thread_unlock(td); 780 PROC_LOCK(p); 781 if (return_instead == 0) 782 p->p_boundary_count--; 783 } 784 return (0); 785 } 786 787 void 788 thread_suspend_switch(struct thread *td) 789 { 790 struct proc *p; 791 792 p = td->td_proc; 793 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 794 PROC_LOCK_ASSERT(p, MA_OWNED); 795 PROC_SLOCK_ASSERT(p, MA_OWNED); 796 /* 797 * We implement thread_suspend_one in stages here to avoid 798 * dropping the proc lock while the thread lock is owned. 799 */ 800 thread_stopped(p); 801 p->p_suspcount++; 802 PROC_UNLOCK(p); 803 thread_lock(td); 804 td->td_flags &= ~TDF_NEEDSUSPCHK; 805 TD_SET_SUSPENDED(td); 806 sched_sleep(td, 0); 807 PROC_SUNLOCK(p); 808 DROP_GIANT(); 809 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 810 thread_unlock(td); 811 PICKUP_GIANT(); 812 PROC_LOCK(p); 813 PROC_SLOCK(p); 814 } 815 816 void 817 thread_suspend_one(struct thread *td) 818 { 819 struct proc *p = td->td_proc; 820 821 PROC_SLOCK_ASSERT(p, MA_OWNED); 822 THREAD_LOCK_ASSERT(td, MA_OWNED); 823 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 824 p->p_suspcount++; 825 td->td_flags &= ~TDF_NEEDSUSPCHK; 826 TD_SET_SUSPENDED(td); 827 sched_sleep(td, 0); 828 } 829 830 int 831 thread_unsuspend_one(struct thread *td) 832 { 833 struct proc *p = td->td_proc; 834 835 PROC_SLOCK_ASSERT(p, MA_OWNED); 836 THREAD_LOCK_ASSERT(td, MA_OWNED); 837 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 838 TD_CLR_SUSPENDED(td); 839 p->p_suspcount--; 840 return (setrunnable(td)); 841 } 842 843 /* 844 * Allow all threads blocked by single threading to continue running. 845 */ 846 void 847 thread_unsuspend(struct proc *p) 848 { 849 struct thread *td; 850 int wakeup_swapper; 851 852 PROC_LOCK_ASSERT(p, MA_OWNED); 853 PROC_SLOCK_ASSERT(p, MA_OWNED); 854 wakeup_swapper = 0; 855 if (!P_SHOULDSTOP(p)) { 856 FOREACH_THREAD_IN_PROC(p, td) { 857 thread_lock(td); 858 if (TD_IS_SUSPENDED(td)) { 859 wakeup_swapper |= thread_unsuspend_one(td); 860 } 861 thread_unlock(td); 862 } 863 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 864 (p->p_numthreads == p->p_suspcount)) { 865 /* 866 * Stopping everything also did the job for the single 867 * threading request. Now we've downgraded to single-threaded, 868 * let it continue. 869 */ 870 thread_lock(p->p_singlethread); 871 wakeup_swapper = thread_unsuspend_one(p->p_singlethread); 872 thread_unlock(p->p_singlethread); 873 } 874 if (wakeup_swapper) 875 kick_proc0(); 876 } 877 878 /* 879 * End the single threading mode.. 880 */ 881 void 882 thread_single_end(void) 883 { 884 struct thread *td; 885 struct proc *p; 886 int wakeup_swapper; 887 888 td = curthread; 889 p = td->td_proc; 890 PROC_LOCK_ASSERT(p, MA_OWNED); 891 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 892 PROC_SLOCK(p); 893 p->p_singlethread = NULL; 894 wakeup_swapper = 0; 895 /* 896 * If there are other threads they may now run, 897 * unless of course there is a blanket 'stop order' 898 * on the process. The single threader must be allowed 899 * to continue however as this is a bad place to stop. 900 */ 901 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 902 FOREACH_THREAD_IN_PROC(p, td) { 903 thread_lock(td); 904 if (TD_IS_SUSPENDED(td)) { 905 wakeup_swapper |= thread_unsuspend_one(td); 906 } 907 thread_unlock(td); 908 } 909 } 910 PROC_SUNLOCK(p); 911 if (wakeup_swapper) 912 kick_proc0(); 913 } 914 915 struct thread * 916 thread_find(struct proc *p, lwpid_t tid) 917 { 918 struct thread *td; 919 920 PROC_LOCK_ASSERT(p, MA_OWNED); 921 FOREACH_THREAD_IN_PROC(p, td) { 922 if (td->td_tid == tid) 923 break; 924 } 925 return (td); 926 } 927