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 /* 69 * thread related storage. 70 */ 71 static uma_zone_t thread_zone; 72 73 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 74 static struct mtx zombie_lock; 75 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 76 77 static void thread_zombie(struct thread *); 78 79 #define TID_BUFFER_SIZE 1024 80 81 struct mtx tid_lock; 82 static struct unrhdr *tid_unrhdr; 83 static lwpid_t tid_buffer[TID_BUFFER_SIZE]; 84 static int tid_head, tid_tail; 85 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 86 87 struct tidhashhead *tidhashtbl; 88 u_long tidhash; 89 struct rwlock tidhash_lock; 90 91 static lwpid_t 92 tid_alloc(void) 93 { 94 lwpid_t tid; 95 96 tid = alloc_unr(tid_unrhdr); 97 if (tid != -1) 98 return (tid); 99 mtx_lock(&tid_lock); 100 if (tid_head == tid_tail) { 101 mtx_unlock(&tid_lock); 102 return (-1); 103 } 104 tid = tid_buffer[tid_head]; 105 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 106 mtx_unlock(&tid_lock); 107 return (tid); 108 } 109 110 static void 111 tid_free(lwpid_t tid) 112 { 113 lwpid_t tmp_tid = -1; 114 115 mtx_lock(&tid_lock); 116 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { 117 tmp_tid = tid_buffer[tid_head]; 118 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 119 } 120 tid_buffer[tid_tail] = tid; 121 tid_tail = (tid_tail + 1) % TID_BUFFER_SIZE; 122 mtx_unlock(&tid_lock); 123 if (tmp_tid != -1) 124 free_unr(tid_unrhdr, tmp_tid); 125 } 126 127 /* 128 * Prepare a thread for use. 129 */ 130 static int 131 thread_ctor(void *mem, int size, void *arg, int flags) 132 { 133 struct thread *td; 134 135 td = (struct thread *)mem; 136 td->td_state = TDS_INACTIVE; 137 td->td_oncpu = NOCPU; 138 139 td->td_tid = tid_alloc(); 140 141 /* 142 * Note that td_critnest begins life as 1 because the thread is not 143 * running and is thereby implicitly waiting to be on the receiving 144 * end of a context switch. 145 */ 146 td->td_critnest = 1; 147 td->td_lend_user_pri = PRI_MAX; 148 EVENTHANDLER_INVOKE(thread_ctor, td); 149 #ifdef AUDIT 150 audit_thread_alloc(td); 151 #endif 152 umtx_thread_alloc(td); 153 return (0); 154 } 155 156 /* 157 * Reclaim a thread after use. 158 */ 159 static void 160 thread_dtor(void *mem, int size, void *arg) 161 { 162 struct thread *td; 163 164 td = (struct thread *)mem; 165 166 #ifdef INVARIANTS 167 /* Verify that this thread is in a safe state to free. */ 168 switch (td->td_state) { 169 case TDS_INHIBITED: 170 case TDS_RUNNING: 171 case TDS_CAN_RUN: 172 case TDS_RUNQ: 173 /* 174 * We must never unlink a thread that is in one of 175 * these states, because it is currently active. 176 */ 177 panic("bad state for thread unlinking"); 178 /* NOTREACHED */ 179 case TDS_INACTIVE: 180 break; 181 default: 182 panic("bad thread state"); 183 /* NOTREACHED */ 184 } 185 #endif 186 #ifdef AUDIT 187 audit_thread_free(td); 188 #endif 189 /* Free all OSD associated to this thread. */ 190 osd_thread_exit(td); 191 192 EVENTHANDLER_INVOKE(thread_dtor, td); 193 tid_free(td->td_tid); 194 } 195 196 /* 197 * Initialize type-stable parts of a thread (when newly created). 198 */ 199 static int 200 thread_init(void *mem, int size, int flags) 201 { 202 struct thread *td; 203 204 td = (struct thread *)mem; 205 206 td->td_sleepqueue = sleepq_alloc(); 207 td->td_turnstile = turnstile_alloc(); 208 td->td_rlqe = NULL; 209 EVENTHANDLER_INVOKE(thread_init, td); 210 td->td_sched = (struct td_sched *)&td[1]; 211 umtx_thread_init(td); 212 td->td_kstack = 0; 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 umtx_thread_exit(td); 418 /* 419 * drop FPU & debug register state storage, or any other 420 * architecture specific resources that 421 * would not be on a new untouched process. 422 */ 423 cpu_thread_exit(td); /* XXXSMP */ 424 425 /* 426 * The last thread is left attached to the process 427 * So that the whole bundle gets recycled. Skip 428 * all this stuff if we never had threads. 429 * EXIT clears all sign of other threads when 430 * it goes to single threading, so the last thread always 431 * takes the short path. 432 */ 433 if (p->p_flag & P_HADTHREADS) { 434 if (p->p_numthreads > 1) { 435 atomic_add_int(&td->td_proc->p_exitthreads, 1); 436 thread_unlink(td); 437 td2 = FIRST_THREAD_IN_PROC(p); 438 sched_exit_thread(td2, td); 439 440 /* 441 * The test below is NOT true if we are the 442 * sole exiting thread. P_STOPPED_SINGLE is unset 443 * in exit1() after it is the only survivor. 444 */ 445 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 446 if (p->p_numthreads == p->p_suspcount) { 447 thread_lock(p->p_singlethread); 448 wakeup_swapper = thread_unsuspend_one( 449 p->p_singlethread); 450 thread_unlock(p->p_singlethread); 451 if (wakeup_swapper) 452 kick_proc0(); 453 } 454 } 455 456 PCPU_SET(deadthread, td); 457 } else { 458 /* 459 * The last thread is exiting.. but not through exit() 460 */ 461 panic ("thread_exit: Last thread exiting on its own"); 462 } 463 } 464 #ifdef HWPMC_HOOKS 465 /* 466 * If this thread is part of a process that is being tracked by hwpmc(4), 467 * inform the module of the thread's impending exit. 468 */ 469 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 470 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 471 #endif 472 PROC_UNLOCK(p); 473 474 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 475 new_switchtime = cpu_ticks(); 476 runtime = new_switchtime - PCPU_GET(switchtime); 477 td->td_runtime += runtime; 478 td->td_incruntime += runtime; 479 PCPU_SET(switchtime, new_switchtime); 480 PCPU_SET(switchticks, ticks); 481 PCPU_INC(cnt.v_swtch); 482 483 /* Save our resource usage in our process. */ 484 td->td_ru.ru_nvcsw++; 485 ruxagg(p, td); 486 rucollect(&p->p_ru, &td->td_ru); 487 488 thread_lock(td); 489 PROC_SUNLOCK(p); 490 td->td_state = TDS_INACTIVE; 491 #ifdef WITNESS 492 witness_thread_exit(td); 493 #endif 494 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 495 sched_throw(td); 496 panic("I'm a teapot!"); 497 /* NOTREACHED */ 498 } 499 500 /* 501 * Do any thread specific cleanups that may be needed in wait() 502 * called with Giant, proc and schedlock not held. 503 */ 504 void 505 thread_wait(struct proc *p) 506 { 507 struct thread *td; 508 509 mtx_assert(&Giant, MA_NOTOWNED); 510 KASSERT(p->p_numthreads == 1, ("multiple threads in thread_wait()")); 511 KASSERT(p->p_exitthreads == 0, ("p_exitthreads leaking")); 512 td = FIRST_THREAD_IN_PROC(p); 513 /* Lock the last thread so we spin until it exits cpu_throw(). */ 514 thread_lock(td); 515 thread_unlock(td); 516 lock_profile_thread_exit(td); 517 cpuset_rel(td->td_cpuset); 518 td->td_cpuset = NULL; 519 cpu_thread_clean(td); 520 crfree(td->td_ucred); 521 thread_reap(); /* check for zombie threads etc. */ 522 } 523 524 /* 525 * Link a thread to a process. 526 * set up anything that needs to be initialized for it to 527 * be used by the process. 528 */ 529 void 530 thread_link(struct thread *td, struct proc *p) 531 { 532 533 /* 534 * XXX This can't be enabled because it's called for proc0 before 535 * its lock has been created. 536 * PROC_LOCK_ASSERT(p, MA_OWNED); 537 */ 538 td->td_state = TDS_INACTIVE; 539 td->td_proc = p; 540 td->td_flags = TDF_INMEM; 541 542 LIST_INIT(&td->td_contested); 543 LIST_INIT(&td->td_lprof[0]); 544 LIST_INIT(&td->td_lprof[1]); 545 sigqueue_init(&td->td_sigqueue, p); 546 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 547 TAILQ_INSERT_TAIL(&p->p_threads, td, td_plist); 548 p->p_numthreads++; 549 } 550 551 /* 552 * Called from: 553 * thread_exit() 554 */ 555 void 556 thread_unlink(struct thread *td) 557 { 558 struct proc *p = td->td_proc; 559 560 PROC_LOCK_ASSERT(p, MA_OWNED); 561 TAILQ_REMOVE(&p->p_threads, td, td_plist); 562 p->p_numthreads--; 563 /* could clear a few other things here */ 564 /* Must NOT clear links to proc! */ 565 } 566 567 static int 568 calc_remaining(struct proc *p, int mode) 569 { 570 int remaining; 571 572 PROC_LOCK_ASSERT(p, MA_OWNED); 573 PROC_SLOCK_ASSERT(p, MA_OWNED); 574 if (mode == SINGLE_EXIT) 575 remaining = p->p_numthreads; 576 else if (mode == SINGLE_BOUNDARY) 577 remaining = p->p_numthreads - p->p_boundary_count; 578 else if (mode == SINGLE_NO_EXIT) 579 remaining = p->p_numthreads - p->p_suspcount; 580 else 581 panic("calc_remaining: wrong mode %d", mode); 582 return (remaining); 583 } 584 585 /* 586 * Enforce single-threading. 587 * 588 * Returns 1 if the caller must abort (another thread is waiting to 589 * exit the process or similar). Process is locked! 590 * Returns 0 when you are successfully the only thread running. 591 * A process has successfully single threaded in the suspend mode when 592 * There are no threads in user mode. Threads in the kernel must be 593 * allowed to continue until they get to the user boundary. They may even 594 * copy out their return values and data before suspending. They may however be 595 * accelerated in reaching the user boundary as we will wake up 596 * any sleeping threads that are interruptable. (PCATCH). 597 */ 598 int 599 thread_single(int mode) 600 { 601 struct thread *td; 602 struct thread *td2; 603 struct proc *p; 604 int remaining, wakeup_swapper; 605 606 td = curthread; 607 p = td->td_proc; 608 mtx_assert(&Giant, MA_NOTOWNED); 609 PROC_LOCK_ASSERT(p, MA_OWNED); 610 611 if ((p->p_flag & P_HADTHREADS) == 0) 612 return (0); 613 614 /* Is someone already single threading? */ 615 if (p->p_singlethread != NULL && p->p_singlethread != td) 616 return (1); 617 618 if (mode == SINGLE_EXIT) { 619 p->p_flag |= P_SINGLE_EXIT; 620 p->p_flag &= ~P_SINGLE_BOUNDARY; 621 } else { 622 p->p_flag &= ~P_SINGLE_EXIT; 623 if (mode == SINGLE_BOUNDARY) 624 p->p_flag |= P_SINGLE_BOUNDARY; 625 else 626 p->p_flag &= ~P_SINGLE_BOUNDARY; 627 } 628 p->p_flag |= P_STOPPED_SINGLE; 629 PROC_SLOCK(p); 630 p->p_singlethread = td; 631 remaining = calc_remaining(p, mode); 632 while (remaining != 1) { 633 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 634 goto stopme; 635 wakeup_swapper = 0; 636 FOREACH_THREAD_IN_PROC(p, td2) { 637 if (td2 == td) 638 continue; 639 thread_lock(td2); 640 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 641 if (TD_IS_INHIBITED(td2)) { 642 switch (mode) { 643 case SINGLE_EXIT: 644 if (TD_IS_SUSPENDED(td2)) 645 wakeup_swapper |= 646 thread_unsuspend_one(td2); 647 if (TD_ON_SLEEPQ(td2) && 648 (td2->td_flags & TDF_SINTR)) 649 wakeup_swapper |= 650 sleepq_abort(td2, EINTR); 651 break; 652 case SINGLE_BOUNDARY: 653 if (TD_IS_SUSPENDED(td2) && 654 !(td2->td_flags & TDF_BOUNDARY)) 655 wakeup_swapper |= 656 thread_unsuspend_one(td2); 657 if (TD_ON_SLEEPQ(td2) && 658 (td2->td_flags & TDF_SINTR)) 659 wakeup_swapper |= 660 sleepq_abort(td2, ERESTART); 661 break; 662 case SINGLE_NO_EXIT: 663 if (TD_IS_SUSPENDED(td2) && 664 !(td2->td_flags & TDF_BOUNDARY)) 665 wakeup_swapper |= 666 thread_unsuspend_one(td2); 667 if (TD_ON_SLEEPQ(td2) && 668 (td2->td_flags & TDF_SINTR)) 669 wakeup_swapper |= 670 sleepq_abort(td2, ERESTART); 671 break; 672 default: 673 break; 674 } 675 } 676 #ifdef SMP 677 else if (TD_IS_RUNNING(td2) && td != td2) { 678 forward_signal(td2); 679 } 680 #endif 681 thread_unlock(td2); 682 } 683 if (wakeup_swapper) 684 kick_proc0(); 685 remaining = calc_remaining(p, mode); 686 687 /* 688 * Maybe we suspended some threads.. was it enough? 689 */ 690 if (remaining == 1) 691 break; 692 693 stopme: 694 /* 695 * Wake us up when everyone else has suspended. 696 * In the mean time we suspend as well. 697 */ 698 thread_suspend_switch(td); 699 remaining = calc_remaining(p, mode); 700 } 701 if (mode == SINGLE_EXIT) { 702 /* 703 * Convert the process to an unthreaded process. The 704 * SINGLE_EXIT is called by exit1() or execve(), in 705 * both cases other threads must be retired. 706 */ 707 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 708 p->p_singlethread = NULL; 709 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 710 711 /* 712 * Wait for any remaining threads to exit cpu_throw(). 713 */ 714 while (p->p_exitthreads != 0) { 715 PROC_SUNLOCK(p); 716 PROC_UNLOCK(p); 717 sched_relinquish(td); 718 PROC_LOCK(p); 719 PROC_SLOCK(p); 720 } 721 } 722 PROC_SUNLOCK(p); 723 return (0); 724 } 725 726 /* 727 * Called in from locations that can safely check to see 728 * whether we have to suspend or at least throttle for a 729 * single-thread event (e.g. fork). 730 * 731 * Such locations include userret(). 732 * If the "return_instead" argument is non zero, the thread must be able to 733 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 734 * 735 * The 'return_instead' argument tells the function if it may do a 736 * thread_exit() or suspend, or whether the caller must abort and back 737 * out instead. 738 * 739 * If the thread that set the single_threading request has set the 740 * P_SINGLE_EXIT bit in the process flags then this call will never return 741 * if 'return_instead' is false, but will exit. 742 * 743 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 744 *---------------+--------------------+--------------------- 745 * 0 | returns 0 | returns 0 or 1 746 * | when ST ends | immediately 747 *---------------+--------------------+--------------------- 748 * 1 | thread exits | returns 1 749 * | | immediately 750 * 0 = thread_exit() or suspension ok, 751 * other = return error instead of stopping the thread. 752 * 753 * While a full suspension is under effect, even a single threading 754 * thread would be suspended if it made this call (but it shouldn't). 755 * This call should only be made from places where 756 * thread_exit() would be safe as that may be the outcome unless 757 * return_instead is set. 758 */ 759 int 760 thread_suspend_check(int return_instead) 761 { 762 struct thread *td; 763 struct proc *p; 764 int wakeup_swapper; 765 766 td = curthread; 767 p = td->td_proc; 768 mtx_assert(&Giant, MA_NOTOWNED); 769 PROC_LOCK_ASSERT(p, MA_OWNED); 770 while (P_SHOULDSTOP(p) || 771 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) { 772 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 773 KASSERT(p->p_singlethread != NULL, 774 ("singlethread not set")); 775 /* 776 * The only suspension in action is a 777 * single-threading. Single threader need not stop. 778 * XXX Should be safe to access unlocked 779 * as it can only be set to be true by us. 780 */ 781 if (p->p_singlethread == td) 782 return (0); /* Exempt from stopping. */ 783 } 784 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 785 return (EINTR); 786 787 /* Should we goto user boundary if we didn't come from there? */ 788 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 789 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 790 return (ERESTART); 791 792 /* 793 * Ignore suspend requests for stop signals if they 794 * are deferred. 795 */ 796 if (P_SHOULDSTOP(p) == P_STOPPED_SIG && 797 td->td_flags & TDF_SBDRY) { 798 KASSERT(return_instead, 799 ("TDF_SBDRY set for unsafe thread_suspend_check")); 800 return (0); 801 } 802 803 /* 804 * If the process is waiting for us to exit, 805 * this thread should just suicide. 806 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 807 */ 808 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 809 PROC_UNLOCK(p); 810 tidhash_remove(td); 811 PROC_LOCK(p); 812 tdsigcleanup(td); 813 PROC_SLOCK(p); 814 thread_stopped(p); 815 thread_exit(); 816 } 817 818 PROC_SLOCK(p); 819 thread_stopped(p); 820 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 821 if (p->p_numthreads == p->p_suspcount + 1) { 822 thread_lock(p->p_singlethread); 823 wakeup_swapper = 824 thread_unsuspend_one(p->p_singlethread); 825 thread_unlock(p->p_singlethread); 826 if (wakeup_swapper) 827 kick_proc0(); 828 } 829 } 830 PROC_UNLOCK(p); 831 thread_lock(td); 832 /* 833 * When a thread suspends, it just 834 * gets taken off all queues. 835 */ 836 thread_suspend_one(td); 837 if (return_instead == 0) { 838 p->p_boundary_count++; 839 td->td_flags |= TDF_BOUNDARY; 840 } 841 PROC_SUNLOCK(p); 842 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 843 if (return_instead == 0) 844 td->td_flags &= ~TDF_BOUNDARY; 845 thread_unlock(td); 846 PROC_LOCK(p); 847 if (return_instead == 0) { 848 PROC_SLOCK(p); 849 p->p_boundary_count--; 850 PROC_SUNLOCK(p); 851 } 852 } 853 return (0); 854 } 855 856 void 857 thread_suspend_switch(struct thread *td) 858 { 859 struct proc *p; 860 861 p = td->td_proc; 862 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 863 PROC_LOCK_ASSERT(p, MA_OWNED); 864 PROC_SLOCK_ASSERT(p, MA_OWNED); 865 /* 866 * We implement thread_suspend_one in stages here to avoid 867 * dropping the proc lock while the thread lock is owned. 868 */ 869 thread_stopped(p); 870 p->p_suspcount++; 871 PROC_UNLOCK(p); 872 thread_lock(td); 873 td->td_flags &= ~TDF_NEEDSUSPCHK; 874 TD_SET_SUSPENDED(td); 875 sched_sleep(td, 0); 876 PROC_SUNLOCK(p); 877 DROP_GIANT(); 878 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 879 thread_unlock(td); 880 PICKUP_GIANT(); 881 PROC_LOCK(p); 882 PROC_SLOCK(p); 883 } 884 885 void 886 thread_suspend_one(struct thread *td) 887 { 888 struct proc *p = td->td_proc; 889 890 PROC_SLOCK_ASSERT(p, MA_OWNED); 891 THREAD_LOCK_ASSERT(td, MA_OWNED); 892 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 893 p->p_suspcount++; 894 td->td_flags &= ~TDF_NEEDSUSPCHK; 895 TD_SET_SUSPENDED(td); 896 sched_sleep(td, 0); 897 } 898 899 int 900 thread_unsuspend_one(struct thread *td) 901 { 902 struct proc *p = td->td_proc; 903 904 PROC_SLOCK_ASSERT(p, MA_OWNED); 905 THREAD_LOCK_ASSERT(td, MA_OWNED); 906 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 907 TD_CLR_SUSPENDED(td); 908 p->p_suspcount--; 909 return (setrunnable(td)); 910 } 911 912 /* 913 * Allow all threads blocked by single threading to continue running. 914 */ 915 void 916 thread_unsuspend(struct proc *p) 917 { 918 struct thread *td; 919 int wakeup_swapper; 920 921 PROC_LOCK_ASSERT(p, MA_OWNED); 922 PROC_SLOCK_ASSERT(p, MA_OWNED); 923 wakeup_swapper = 0; 924 if (!P_SHOULDSTOP(p)) { 925 FOREACH_THREAD_IN_PROC(p, td) { 926 thread_lock(td); 927 if (TD_IS_SUSPENDED(td)) { 928 wakeup_swapper |= thread_unsuspend_one(td); 929 } 930 thread_unlock(td); 931 } 932 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 933 (p->p_numthreads == p->p_suspcount)) { 934 /* 935 * Stopping everything also did the job for the single 936 * threading request. Now we've downgraded to single-threaded, 937 * let it continue. 938 */ 939 thread_lock(p->p_singlethread); 940 wakeup_swapper = thread_unsuspend_one(p->p_singlethread); 941 thread_unlock(p->p_singlethread); 942 } 943 if (wakeup_swapper) 944 kick_proc0(); 945 } 946 947 /* 948 * End the single threading mode.. 949 */ 950 void 951 thread_single_end(void) 952 { 953 struct thread *td; 954 struct proc *p; 955 int wakeup_swapper; 956 957 td = curthread; 958 p = td->td_proc; 959 PROC_LOCK_ASSERT(p, MA_OWNED); 960 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 961 PROC_SLOCK(p); 962 p->p_singlethread = NULL; 963 wakeup_swapper = 0; 964 /* 965 * If there are other threads they may now run, 966 * unless of course there is a blanket 'stop order' 967 * on the process. The single threader must be allowed 968 * to continue however as this is a bad place to stop. 969 */ 970 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 971 FOREACH_THREAD_IN_PROC(p, td) { 972 thread_lock(td); 973 if (TD_IS_SUSPENDED(td)) { 974 wakeup_swapper |= thread_unsuspend_one(td); 975 } 976 thread_unlock(td); 977 } 978 } 979 PROC_SUNLOCK(p); 980 if (wakeup_swapper) 981 kick_proc0(); 982 } 983 984 struct thread * 985 thread_find(struct proc *p, lwpid_t tid) 986 { 987 struct thread *td; 988 989 PROC_LOCK_ASSERT(p, MA_OWNED); 990 FOREACH_THREAD_IN_PROC(p, td) { 991 if (td->td_tid == tid) 992 break; 993 } 994 return (td); 995 } 996 997 /* Locate a thread by number; return with proc lock held. */ 998 struct thread * 999 tdfind(lwpid_t tid, pid_t pid) 1000 { 1001 #define RUN_THRESH 16 1002 struct thread *td; 1003 int run = 0; 1004 1005 rw_rlock(&tidhash_lock); 1006 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1007 if (td->td_tid == tid) { 1008 if (pid != -1 && td->td_proc->p_pid != pid) { 1009 td = NULL; 1010 break; 1011 } 1012 PROC_LOCK(td->td_proc); 1013 if (td->td_proc->p_state == PRS_NEW) { 1014 PROC_UNLOCK(td->td_proc); 1015 td = NULL; 1016 break; 1017 } 1018 if (run > RUN_THRESH) { 1019 if (rw_try_upgrade(&tidhash_lock)) { 1020 LIST_REMOVE(td, td_hash); 1021 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1022 td, td_hash); 1023 rw_wunlock(&tidhash_lock); 1024 return (td); 1025 } 1026 } 1027 break; 1028 } 1029 run++; 1030 } 1031 rw_runlock(&tidhash_lock); 1032 return (td); 1033 } 1034 1035 void 1036 tidhash_add(struct thread *td) 1037 { 1038 rw_wlock(&tidhash_lock); 1039 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1040 rw_wunlock(&tidhash_lock); 1041 } 1042 1043 void 1044 tidhash_remove(struct thread *td) 1045 { 1046 rw_wlock(&tidhash_lock); 1047 LIST_REMOVE(td, td_hash); 1048 rw_wunlock(&tidhash_lock); 1049 } 1050