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 return (0); 213 } 214 215 /* 216 * Tear down type-stable parts of a thread (just before being discarded). 217 */ 218 static void 219 thread_fini(void *mem, int size) 220 { 221 struct thread *td; 222 223 td = (struct thread *)mem; 224 EVENTHANDLER_INVOKE(thread_fini, td); 225 rlqentry_free(td->td_rlqe); 226 turnstile_free(td->td_turnstile); 227 sleepq_free(td->td_sleepqueue); 228 umtx_thread_fini(td); 229 seltdfini(td); 230 } 231 232 /* 233 * For a newly created process, 234 * link up all the structures and its initial threads etc. 235 * called from: 236 * {arch}/{arch}/machdep.c {arch}_init(), init386() etc. 237 * proc_dtor() (should go away) 238 * proc_init() 239 */ 240 void 241 proc_linkup0(struct proc *p, struct thread *td) 242 { 243 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 244 proc_linkup(p, td); 245 } 246 247 void 248 proc_linkup(struct proc *p, struct thread *td) 249 { 250 251 sigqueue_init(&p->p_sigqueue, p); 252 p->p_ksi = ksiginfo_alloc(1); 253 if (p->p_ksi != NULL) { 254 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 255 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 256 } 257 LIST_INIT(&p->p_mqnotifier); 258 p->p_numthreads = 0; 259 thread_link(td, p); 260 } 261 262 /* 263 * Initialize global thread allocation resources. 264 */ 265 void 266 threadinit(void) 267 { 268 269 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 270 271 /* 272 * pid_max cannot be greater than PID_MAX. 273 * leave one number for thread0. 274 */ 275 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 276 277 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 278 thread_ctor, thread_dtor, thread_init, thread_fini, 279 16 - 1, 0); 280 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 281 rw_init(&tidhash_lock, "tidhash"); 282 } 283 284 /* 285 * Place an unused thread on the zombie list. 286 * Use the slpq as that must be unused by now. 287 */ 288 void 289 thread_zombie(struct thread *td) 290 { 291 mtx_lock_spin(&zombie_lock); 292 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 293 mtx_unlock_spin(&zombie_lock); 294 } 295 296 /* 297 * Release a thread that has exited after cpu_throw(). 298 */ 299 void 300 thread_stash(struct thread *td) 301 { 302 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 303 thread_zombie(td); 304 } 305 306 /* 307 * Reap zombie resources. 308 */ 309 void 310 thread_reap(void) 311 { 312 struct thread *td_first, *td_next; 313 314 /* 315 * Don't even bother to lock if none at this instant, 316 * we really don't care about the next instant.. 317 */ 318 if (!TAILQ_EMPTY(&zombie_threads)) { 319 mtx_lock_spin(&zombie_lock); 320 td_first = TAILQ_FIRST(&zombie_threads); 321 if (td_first) 322 TAILQ_INIT(&zombie_threads); 323 mtx_unlock_spin(&zombie_lock); 324 while (td_first) { 325 td_next = TAILQ_NEXT(td_first, td_slpq); 326 if (td_first->td_ucred) 327 crfree(td_first->td_ucred); 328 thread_free(td_first); 329 td_first = td_next; 330 } 331 } 332 } 333 334 /* 335 * Allocate a thread. 336 */ 337 struct thread * 338 thread_alloc(int pages) 339 { 340 struct thread *td; 341 342 thread_reap(); /* check if any zombies to get */ 343 344 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 345 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 346 if (!vm_thread_new(td, pages)) { 347 uma_zfree(thread_zone, td); 348 return (NULL); 349 } 350 cpu_thread_alloc(td); 351 return (td); 352 } 353 354 int 355 thread_alloc_stack(struct thread *td, int pages) 356 { 357 358 KASSERT(td->td_kstack == 0, 359 ("thread_alloc_stack called on a thread with kstack")); 360 if (!vm_thread_new(td, pages)) 361 return (0); 362 cpu_thread_alloc(td); 363 return (1); 364 } 365 366 /* 367 * Deallocate a thread. 368 */ 369 void 370 thread_free(struct thread *td) 371 { 372 373 lock_profile_thread_exit(td); 374 if (td->td_cpuset) 375 cpuset_rel(td->td_cpuset); 376 td->td_cpuset = NULL; 377 cpu_thread_free(td); 378 if (td->td_kstack != 0) 379 vm_thread_dispose(td); 380 uma_zfree(thread_zone, td); 381 } 382 383 /* 384 * Discard the current thread and exit from its context. 385 * Always called with scheduler locked. 386 * 387 * Because we can't free a thread while we're operating under its context, 388 * push the current thread into our CPU's deadthread holder. This means 389 * we needn't worry about someone else grabbing our context before we 390 * do a cpu_throw(). 391 */ 392 void 393 thread_exit(void) 394 { 395 uint64_t runtime, new_switchtime; 396 struct thread *td; 397 struct thread *td2; 398 struct proc *p; 399 int wakeup_swapper; 400 401 td = curthread; 402 p = td->td_proc; 403 404 PROC_SLOCK_ASSERT(p, MA_OWNED); 405 mtx_assert(&Giant, MA_NOTOWNED); 406 407 PROC_LOCK_ASSERT(p, MA_OWNED); 408 KASSERT(p != NULL, ("thread exiting without a process")); 409 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 410 (long)p->p_pid, td->td_name); 411 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 412 413 #ifdef AUDIT 414 AUDIT_SYSCALL_EXIT(0, td); 415 #endif 416 /* 417 * drop FPU & debug register state storage, or any other 418 * architecture specific resources that 419 * would not be on a new untouched process. 420 */ 421 cpu_thread_exit(td); /* XXXSMP */ 422 423 /* 424 * The last thread is left attached to the process 425 * So that the whole bundle gets recycled. Skip 426 * all this stuff if we never had threads. 427 * EXIT clears all sign of other threads when 428 * it goes to single threading, so the last thread always 429 * takes the short path. 430 */ 431 if (p->p_flag & P_HADTHREADS) { 432 if (p->p_numthreads > 1) { 433 atomic_add_int(&td->td_proc->p_exitthreads, 1); 434 thread_unlink(td); 435 td2 = FIRST_THREAD_IN_PROC(p); 436 sched_exit_thread(td2, td); 437 438 /* 439 * The test below is NOT true if we are the 440 * sole exiting thread. P_STOPPED_SINGLE is unset 441 * in exit1() after it is the only survivor. 442 */ 443 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 444 if (p->p_numthreads == p->p_suspcount) { 445 thread_lock(p->p_singlethread); 446 wakeup_swapper = thread_unsuspend_one( 447 p->p_singlethread, p); 448 thread_unlock(p->p_singlethread); 449 if (wakeup_swapper) 450 kick_proc0(); 451 } 452 } 453 454 PCPU_SET(deadthread, td); 455 } else { 456 /* 457 * The last thread is exiting.. but not through exit() 458 */ 459 panic ("thread_exit: Last thread exiting on its own"); 460 } 461 } 462 #ifdef HWPMC_HOOKS 463 /* 464 * If this thread is part of a process that is being tracked by hwpmc(4), 465 * inform the module of the thread's impending exit. 466 */ 467 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 468 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 469 #endif 470 PROC_UNLOCK(p); 471 PROC_STATLOCK(p); 472 thread_lock(td); 473 PROC_SUNLOCK(p); 474 475 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 476 new_switchtime = cpu_ticks(); 477 runtime = new_switchtime - PCPU_GET(switchtime); 478 td->td_runtime += runtime; 479 td->td_incruntime += runtime; 480 PCPU_SET(switchtime, new_switchtime); 481 PCPU_SET(switchticks, ticks); 482 PCPU_INC(cnt.v_swtch); 483 484 /* Save our resource usage in our process. */ 485 td->td_ru.ru_nvcsw++; 486 ruxagg(p, td); 487 rucollect(&p->p_ru, &td->td_ru); 488 PROC_STATUNLOCK(p); 489 490 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 || mode == SINGLE_ALLPROC) 579 remaining = p->p_numthreads - p->p_suspcount; 580 else 581 panic("calc_remaining: wrong mode %d", mode); 582 return (remaining); 583 } 584 585 static int 586 remain_for_mode(int mode) 587 { 588 589 return (mode == SINGLE_ALLPROC ? 0 : 1); 590 } 591 592 static int 593 weed_inhib(int mode, struct thread *td2, struct proc *p) 594 { 595 int wakeup_swapper; 596 597 PROC_LOCK_ASSERT(p, MA_OWNED); 598 PROC_SLOCK_ASSERT(p, MA_OWNED); 599 THREAD_LOCK_ASSERT(td2, MA_OWNED); 600 601 wakeup_swapper = 0; 602 switch (mode) { 603 case SINGLE_EXIT: 604 if (TD_IS_SUSPENDED(td2)) 605 wakeup_swapper |= thread_unsuspend_one(td2, p); 606 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 607 wakeup_swapper |= sleepq_abort(td2, EINTR); 608 break; 609 case SINGLE_BOUNDARY: 610 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 611 wakeup_swapper |= thread_unsuspend_one(td2, p); 612 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 613 wakeup_swapper |= sleepq_abort(td2, ERESTART); 614 break; 615 case SINGLE_NO_EXIT: 616 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & TDF_BOUNDARY) == 0) 617 wakeup_swapper |= thread_unsuspend_one(td2, p); 618 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) 619 wakeup_swapper |= sleepq_abort(td2, ERESTART); 620 break; 621 case SINGLE_ALLPROC: 622 /* 623 * ALLPROC suspend tries to avoid spurious EINTR for 624 * threads sleeping interruptable, by suspending the 625 * thread directly, similarly to sig_suspend_threads(). 626 * Since such sleep is not performed at the user 627 * boundary, TDF_BOUNDARY flag is not set, and TDF_ALLPROCSUSP 628 * is used to avoid immediate un-suspend. 629 */ 630 if (TD_IS_SUSPENDED(td2) && (td2->td_flags & (TDF_BOUNDARY | 631 TDF_ALLPROCSUSP)) == 0) 632 wakeup_swapper |= thread_unsuspend_one(td2, p); 633 if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR) != 0) { 634 if ((td2->td_flags & TDF_SBDRY) == 0) { 635 thread_suspend_one(td2); 636 td2->td_flags |= TDF_ALLPROCSUSP; 637 } else { 638 wakeup_swapper |= sleepq_abort(td2, ERESTART); 639 } 640 } 641 break; 642 } 643 return (wakeup_swapper); 644 } 645 646 /* 647 * Enforce single-threading. 648 * 649 * Returns 1 if the caller must abort (another thread is waiting to 650 * exit the process or similar). Process is locked! 651 * Returns 0 when you are successfully the only thread running. 652 * A process has successfully single threaded in the suspend mode when 653 * There are no threads in user mode. Threads in the kernel must be 654 * allowed to continue until they get to the user boundary. They may even 655 * copy out their return values and data before suspending. They may however be 656 * accelerated in reaching the user boundary as we will wake up 657 * any sleeping threads that are interruptable. (PCATCH). 658 */ 659 int 660 thread_single(struct proc *p, int mode) 661 { 662 struct thread *td; 663 struct thread *td2; 664 int remaining, wakeup_swapper; 665 666 td = curthread; 667 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 668 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 669 ("invalid mode %d", mode)); 670 /* 671 * If allowing non-ALLPROC singlethreading for non-curproc 672 * callers, calc_remaining() and remain_for_mode() should be 673 * adjusted to also account for td->td_proc != p. For now 674 * this is not implemented because it is not used. 675 */ 676 KASSERT((mode == SINGLE_ALLPROC && td->td_proc != p) || 677 (mode != SINGLE_ALLPROC && td->td_proc == p), 678 ("mode %d proc %p curproc %p", mode, p, td->td_proc)); 679 mtx_assert(&Giant, MA_NOTOWNED); 680 PROC_LOCK_ASSERT(p, MA_OWNED); 681 682 if ((p->p_flag & P_HADTHREADS) == 0 && mode != SINGLE_ALLPROC) 683 return (0); 684 685 /* Is someone already single threading? */ 686 if (p->p_singlethread != NULL && p->p_singlethread != td) 687 return (1); 688 689 if (mode == SINGLE_EXIT) { 690 p->p_flag |= P_SINGLE_EXIT; 691 p->p_flag &= ~P_SINGLE_BOUNDARY; 692 } else { 693 p->p_flag &= ~P_SINGLE_EXIT; 694 if (mode == SINGLE_BOUNDARY) 695 p->p_flag |= P_SINGLE_BOUNDARY; 696 else 697 p->p_flag &= ~P_SINGLE_BOUNDARY; 698 } 699 if (mode == SINGLE_ALLPROC) 700 p->p_flag |= P_TOTAL_STOP; 701 p->p_flag |= P_STOPPED_SINGLE; 702 PROC_SLOCK(p); 703 p->p_singlethread = td; 704 remaining = calc_remaining(p, mode); 705 while (remaining != remain_for_mode(mode)) { 706 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 707 goto stopme; 708 wakeup_swapper = 0; 709 FOREACH_THREAD_IN_PROC(p, td2) { 710 if (td2 == td) 711 continue; 712 thread_lock(td2); 713 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 714 if (TD_IS_INHIBITED(td2)) { 715 wakeup_swapper |= weed_inhib(mode, td2, p); 716 #ifdef SMP 717 } else if (TD_IS_RUNNING(td2) && td != td2) { 718 forward_signal(td2); 719 #endif 720 } 721 thread_unlock(td2); 722 } 723 if (wakeup_swapper) 724 kick_proc0(); 725 remaining = calc_remaining(p, mode); 726 727 /* 728 * Maybe we suspended some threads.. was it enough? 729 */ 730 if (remaining == remain_for_mode(mode)) 731 break; 732 733 stopme: 734 /* 735 * Wake us up when everyone else has suspended. 736 * In the mean time we suspend as well. 737 */ 738 thread_suspend_switch(td, p); 739 remaining = calc_remaining(p, mode); 740 } 741 if (mode == SINGLE_EXIT) { 742 /* 743 * Convert the process to an unthreaded process. The 744 * SINGLE_EXIT is called by exit1() or execve(), in 745 * both cases other threads must be retired. 746 */ 747 KASSERT(p->p_numthreads == 1, ("Unthreading with >1 threads")); 748 p->p_singlethread = NULL; 749 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_HADTHREADS); 750 751 /* 752 * Wait for any remaining threads to exit cpu_throw(). 753 */ 754 while (p->p_exitthreads != 0) { 755 PROC_SUNLOCK(p); 756 PROC_UNLOCK(p); 757 sched_relinquish(td); 758 PROC_LOCK(p); 759 PROC_SLOCK(p); 760 } 761 } 762 PROC_SUNLOCK(p); 763 return (0); 764 } 765 766 bool 767 thread_suspend_check_needed(void) 768 { 769 struct proc *p; 770 struct thread *td; 771 772 td = curthread; 773 p = td->td_proc; 774 PROC_LOCK_ASSERT(p, MA_OWNED); 775 return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 && 776 (td->td_dbgflags & TDB_SUSPEND) != 0)); 777 } 778 779 /* 780 * Called in from locations that can safely check to see 781 * whether we have to suspend or at least throttle for a 782 * single-thread event (e.g. fork). 783 * 784 * Such locations include userret(). 785 * If the "return_instead" argument is non zero, the thread must be able to 786 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 787 * 788 * The 'return_instead' argument tells the function if it may do a 789 * thread_exit() or suspend, or whether the caller must abort and back 790 * out instead. 791 * 792 * If the thread that set the single_threading request has set the 793 * P_SINGLE_EXIT bit in the process flags then this call will never return 794 * if 'return_instead' is false, but will exit. 795 * 796 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 797 *---------------+--------------------+--------------------- 798 * 0 | returns 0 | returns 0 or 1 799 * | when ST ends | immediately 800 *---------------+--------------------+--------------------- 801 * 1 | thread exits | returns 1 802 * | | immediately 803 * 0 = thread_exit() or suspension ok, 804 * other = return error instead of stopping the thread. 805 * 806 * While a full suspension is under effect, even a single threading 807 * thread would be suspended if it made this call (but it shouldn't). 808 * This call should only be made from places where 809 * thread_exit() would be safe as that may be the outcome unless 810 * return_instead is set. 811 */ 812 int 813 thread_suspend_check(int return_instead) 814 { 815 struct thread *td; 816 struct proc *p; 817 int wakeup_swapper; 818 819 td = curthread; 820 p = td->td_proc; 821 mtx_assert(&Giant, MA_NOTOWNED); 822 PROC_LOCK_ASSERT(p, MA_OWNED); 823 while (thread_suspend_check_needed()) { 824 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 825 KASSERT(p->p_singlethread != NULL, 826 ("singlethread not set")); 827 /* 828 * The only suspension in action is a 829 * single-threading. Single threader need not stop. 830 * XXX Should be safe to access unlocked 831 * as it can only be set to be true by us. 832 */ 833 if (p->p_singlethread == td) 834 return (0); /* Exempt from stopping. */ 835 } 836 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 837 return (EINTR); 838 839 /* Should we goto user boundary if we didn't come from there? */ 840 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 841 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 842 return (ERESTART); 843 844 /* 845 * Ignore suspend requests for stop signals if they 846 * are deferred. 847 */ 848 if ((P_SHOULDSTOP(p) == P_STOPPED_SIG || 849 (p->p_flag & P_TOTAL_STOP) != 0) && 850 (td->td_flags & TDF_SBDRY) != 0) { 851 KASSERT(return_instead, 852 ("TDF_SBDRY set for unsafe thread_suspend_check")); 853 return (0); 854 } 855 856 /* 857 * If the process is waiting for us to exit, 858 * this thread should just suicide. 859 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 860 */ 861 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 862 PROC_UNLOCK(p); 863 tidhash_remove(td); 864 PROC_LOCK(p); 865 tdsigcleanup(td); 866 umtx_thread_exit(td); 867 PROC_SLOCK(p); 868 thread_stopped(p); 869 thread_exit(); 870 } 871 872 PROC_SLOCK(p); 873 thread_stopped(p); 874 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 875 if (p->p_numthreads == p->p_suspcount + 1) { 876 thread_lock(p->p_singlethread); 877 wakeup_swapper = 878 thread_unsuspend_one(p->p_singlethread, p); 879 thread_unlock(p->p_singlethread); 880 if (wakeup_swapper) 881 kick_proc0(); 882 } 883 } 884 PROC_UNLOCK(p); 885 thread_lock(td); 886 /* 887 * When a thread suspends, it just 888 * gets taken off all queues. 889 */ 890 thread_suspend_one(td); 891 if (return_instead == 0) { 892 p->p_boundary_count++; 893 td->td_flags |= TDF_BOUNDARY; 894 } 895 PROC_SUNLOCK(p); 896 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 897 if (return_instead == 0) 898 td->td_flags &= ~TDF_BOUNDARY; 899 thread_unlock(td); 900 PROC_LOCK(p); 901 if (return_instead == 0) { 902 PROC_SLOCK(p); 903 p->p_boundary_count--; 904 PROC_SUNLOCK(p); 905 } 906 } 907 return (0); 908 } 909 910 void 911 thread_suspend_switch(struct thread *td, struct proc *p) 912 { 913 914 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 915 PROC_LOCK_ASSERT(p, MA_OWNED); 916 PROC_SLOCK_ASSERT(p, MA_OWNED); 917 /* 918 * We implement thread_suspend_one in stages here to avoid 919 * dropping the proc lock while the thread lock is owned. 920 */ 921 if (p == td->td_proc) { 922 thread_stopped(p); 923 p->p_suspcount++; 924 } 925 PROC_UNLOCK(p); 926 thread_lock(td); 927 td->td_flags &= ~TDF_NEEDSUSPCHK; 928 TD_SET_SUSPENDED(td); 929 sched_sleep(td, 0); 930 PROC_SUNLOCK(p); 931 DROP_GIANT(); 932 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 933 thread_unlock(td); 934 PICKUP_GIANT(); 935 PROC_LOCK(p); 936 PROC_SLOCK(p); 937 } 938 939 void 940 thread_suspend_one(struct thread *td) 941 { 942 struct proc *p; 943 944 p = td->td_proc; 945 PROC_SLOCK_ASSERT(p, MA_OWNED); 946 THREAD_LOCK_ASSERT(td, MA_OWNED); 947 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 948 p->p_suspcount++; 949 td->td_flags &= ~TDF_NEEDSUSPCHK; 950 TD_SET_SUSPENDED(td); 951 sched_sleep(td, 0); 952 } 953 954 int 955 thread_unsuspend_one(struct thread *td, struct proc *p) 956 { 957 958 THREAD_LOCK_ASSERT(td, MA_OWNED); 959 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 960 TD_CLR_SUSPENDED(td); 961 td->td_flags &= ~TDF_ALLPROCSUSP; 962 if (td->td_proc == p) { 963 PROC_SLOCK_ASSERT(p, MA_OWNED); 964 p->p_suspcount--; 965 } 966 return (setrunnable(td)); 967 } 968 969 /* 970 * Allow all threads blocked by single threading to continue running. 971 */ 972 void 973 thread_unsuspend(struct proc *p) 974 { 975 struct thread *td; 976 int wakeup_swapper; 977 978 PROC_LOCK_ASSERT(p, MA_OWNED); 979 PROC_SLOCK_ASSERT(p, MA_OWNED); 980 wakeup_swapper = 0; 981 if (!P_SHOULDSTOP(p)) { 982 FOREACH_THREAD_IN_PROC(p, td) { 983 thread_lock(td); 984 if (TD_IS_SUSPENDED(td)) { 985 wakeup_swapper |= thread_unsuspend_one(td, p); 986 } 987 thread_unlock(td); 988 } 989 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 990 (p->p_numthreads == p->p_suspcount)) { 991 /* 992 * Stopping everything also did the job for the single 993 * threading request. Now we've downgraded to single-threaded, 994 * let it continue. 995 */ 996 if (p->p_singlethread->td_proc == p) { 997 thread_lock(p->p_singlethread); 998 wakeup_swapper = thread_unsuspend_one( 999 p->p_singlethread, p); 1000 thread_unlock(p->p_singlethread); 1001 } 1002 } 1003 if (wakeup_swapper) 1004 kick_proc0(); 1005 } 1006 1007 /* 1008 * End the single threading mode.. 1009 */ 1010 void 1011 thread_single_end(struct proc *p, int mode) 1012 { 1013 struct thread *td; 1014 int wakeup_swapper; 1015 1016 KASSERT(mode == SINGLE_EXIT || mode == SINGLE_BOUNDARY || 1017 mode == SINGLE_ALLPROC || mode == SINGLE_NO_EXIT, 1018 ("invalid mode %d", mode)); 1019 PROC_LOCK_ASSERT(p, MA_OWNED); 1020 KASSERT((mode == SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) != 0) || 1021 (mode != SINGLE_ALLPROC && (p->p_flag & P_TOTAL_STOP) == 0), 1022 ("mode %d does not match P_TOTAL_STOP", mode)); 1023 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY | 1024 P_TOTAL_STOP); 1025 PROC_SLOCK(p); 1026 p->p_singlethread = NULL; 1027 wakeup_swapper = 0; 1028 /* 1029 * If there are other threads they may now run, 1030 * unless of course there is a blanket 'stop order' 1031 * on the process. The single threader must be allowed 1032 * to continue however as this is a bad place to stop. 1033 */ 1034 if (p->p_numthreads != remain_for_mode(mode) && !P_SHOULDSTOP(p)) { 1035 FOREACH_THREAD_IN_PROC(p, td) { 1036 thread_lock(td); 1037 if (TD_IS_SUSPENDED(td)) { 1038 wakeup_swapper |= thread_unsuspend_one(td, p); 1039 } 1040 thread_unlock(td); 1041 } 1042 } 1043 PROC_SUNLOCK(p); 1044 if (wakeup_swapper) 1045 kick_proc0(); 1046 } 1047 1048 struct thread * 1049 thread_find(struct proc *p, lwpid_t tid) 1050 { 1051 struct thread *td; 1052 1053 PROC_LOCK_ASSERT(p, MA_OWNED); 1054 FOREACH_THREAD_IN_PROC(p, td) { 1055 if (td->td_tid == tid) 1056 break; 1057 } 1058 return (td); 1059 } 1060 1061 /* Locate a thread by number; return with proc lock held. */ 1062 struct thread * 1063 tdfind(lwpid_t tid, pid_t pid) 1064 { 1065 #define RUN_THRESH 16 1066 struct thread *td; 1067 int run = 0; 1068 1069 rw_rlock(&tidhash_lock); 1070 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 1071 if (td->td_tid == tid) { 1072 if (pid != -1 && td->td_proc->p_pid != pid) { 1073 td = NULL; 1074 break; 1075 } 1076 PROC_LOCK(td->td_proc); 1077 if (td->td_proc->p_state == PRS_NEW) { 1078 PROC_UNLOCK(td->td_proc); 1079 td = NULL; 1080 break; 1081 } 1082 if (run > RUN_THRESH) { 1083 if (rw_try_upgrade(&tidhash_lock)) { 1084 LIST_REMOVE(td, td_hash); 1085 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1086 td, td_hash); 1087 rw_wunlock(&tidhash_lock); 1088 return (td); 1089 } 1090 } 1091 break; 1092 } 1093 run++; 1094 } 1095 rw_runlock(&tidhash_lock); 1096 return (td); 1097 } 1098 1099 void 1100 tidhash_add(struct thread *td) 1101 { 1102 rw_wlock(&tidhash_lock); 1103 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1104 rw_wunlock(&tidhash_lock); 1105 } 1106 1107 void 1108 tidhash_remove(struct thread *td) 1109 { 1110 rw_wlock(&tidhash_lock); 1111 LIST_REMOVE(td, td_hash); 1112 rw_wunlock(&tidhash_lock); 1113 } 1114