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/sched.h> 44 #include <sys/sleepqueue.h> 45 #include <sys/selinfo.h> 46 #include <sys/turnstile.h> 47 #include <sys/ktr.h> 48 #include <sys/rwlock.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 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 68 static struct mtx zombie_lock; 69 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN); 70 71 static void thread_zombie(struct thread *); 72 73 #define TID_BUFFER_SIZE 1024 74 75 struct mtx tid_lock; 76 static struct unrhdr *tid_unrhdr; 77 static lwpid_t tid_buffer[TID_BUFFER_SIZE]; 78 static int tid_head, tid_tail; 79 static MALLOC_DEFINE(M_TIDHASH, "tidhash", "thread hash"); 80 81 struct tidhashhead *tidhashtbl; 82 u_long tidhash; 83 struct rwlock tidhash_lock; 84 85 static lwpid_t 86 tid_alloc(void) 87 { 88 lwpid_t tid; 89 90 tid = alloc_unr(tid_unrhdr); 91 if (tid != -1) 92 return (tid); 93 mtx_lock(&tid_lock); 94 if (tid_head == tid_tail) { 95 mtx_unlock(&tid_lock); 96 return (-1); 97 } 98 tid = tid_buffer[tid_head++]; 99 tid_head %= TID_BUFFER_SIZE; 100 mtx_unlock(&tid_lock); 101 return (tid); 102 } 103 104 static void 105 tid_free(lwpid_t tid) 106 { 107 lwpid_t tmp_tid = -1; 108 109 mtx_lock(&tid_lock); 110 if ((tid_tail + 1) % TID_BUFFER_SIZE == tid_head) { 111 tmp_tid = tid_buffer[tid_head++]; 112 tid_head = (tid_head + 1) % TID_BUFFER_SIZE; 113 } 114 tid_buffer[tid_tail++] = tid; 115 tid_tail %= TID_BUFFER_SIZE; 116 mtx_unlock(&tid_lock); 117 if (tmp_tid != -1) 118 free_unr(tid_unrhdr, tmp_tid); 119 } 120 121 /* 122 * Prepare a thread for use. 123 */ 124 static int 125 thread_ctor(void *mem, int size, void *arg, int flags) 126 { 127 struct thread *td; 128 129 td = (struct thread *)mem; 130 td->td_state = TDS_INACTIVE; 131 td->td_oncpu = NOCPU; 132 133 td->td_tid = tid_alloc(); 134 135 /* 136 * Note that td_critnest begins life as 1 because the thread is not 137 * running and is thereby implicitly waiting to be on the receiving 138 * end of a context switch. 139 */ 140 td->td_critnest = 1; 141 td->td_lend_user_pri = PRI_MAX; 142 EVENTHANDLER_INVOKE(thread_ctor, td); 143 #ifdef AUDIT 144 audit_thread_alloc(td); 145 #endif 146 umtx_thread_alloc(td); 147 return (0); 148 } 149 150 /* 151 * Reclaim a thread after use. 152 */ 153 static void 154 thread_dtor(void *mem, int size, void *arg) 155 { 156 struct thread *td; 157 158 td = (struct thread *)mem; 159 160 #ifdef INVARIANTS 161 /* Verify that this thread is in a safe state to free. */ 162 switch (td->td_state) { 163 case TDS_INHIBITED: 164 case TDS_RUNNING: 165 case TDS_CAN_RUN: 166 case TDS_RUNQ: 167 /* 168 * We must never unlink a thread that is in one of 169 * these states, because it is currently active. 170 */ 171 panic("bad state for thread unlinking"); 172 /* NOTREACHED */ 173 case TDS_INACTIVE: 174 break; 175 default: 176 panic("bad thread state"); 177 /* NOTREACHED */ 178 } 179 #endif 180 #ifdef AUDIT 181 audit_thread_free(td); 182 #endif 183 /* Free all OSD associated to this thread. */ 184 osd_thread_exit(td); 185 186 EVENTHANDLER_INVOKE(thread_dtor, td); 187 tid_free(td->td_tid); 188 } 189 190 /* 191 * Initialize type-stable parts of a thread (when newly created). 192 */ 193 static int 194 thread_init(void *mem, int size, int flags) 195 { 196 struct thread *td; 197 198 td = (struct thread *)mem; 199 200 td->td_sleepqueue = sleepq_alloc(); 201 td->td_turnstile = turnstile_alloc(); 202 EVENTHANDLER_INVOKE(thread_init, td); 203 td->td_sched = (struct td_sched *)&td[1]; 204 umtx_thread_init(td); 205 td->td_kstack = 0; 206 return (0); 207 } 208 209 /* 210 * Tear down type-stable parts of a thread (just before being discarded). 211 */ 212 static void 213 thread_fini(void *mem, int size) 214 { 215 struct thread *td; 216 217 td = (struct thread *)mem; 218 EVENTHANDLER_INVOKE(thread_fini, td); 219 turnstile_free(td->td_turnstile); 220 sleepq_free(td->td_sleepqueue); 221 umtx_thread_fini(td); 222 seltdfini(td); 223 } 224 225 /* 226 * For a newly created process, 227 * link up all the structures and its initial threads etc. 228 * called from: 229 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 230 * proc_dtor() (should go away) 231 * proc_init() 232 */ 233 void 234 proc_linkup0(struct proc *p, struct thread *td) 235 { 236 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 237 proc_linkup(p, td); 238 } 239 240 void 241 proc_linkup(struct proc *p, struct thread *td) 242 { 243 244 sigqueue_init(&p->p_sigqueue, p); 245 p->p_ksi = ksiginfo_alloc(1); 246 if (p->p_ksi != NULL) { 247 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 248 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 249 } 250 LIST_INIT(&p->p_mqnotifier); 251 p->p_numthreads = 0; 252 thread_link(td, p); 253 } 254 255 /* 256 * Initialize global thread allocation resources. 257 */ 258 void 259 threadinit(void) 260 { 261 262 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 263 /* leave one number for thread0 */ 264 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 265 266 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 267 thread_ctor, thread_dtor, thread_init, thread_fini, 268 16 - 1, 0); 269 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 270 rw_init(&tidhash_lock, "tidhash"); 271 } 272 273 /* 274 * Place an unused thread on the zombie list. 275 * Use the slpq as that must be unused by now. 276 */ 277 void 278 thread_zombie(struct thread *td) 279 { 280 mtx_lock_spin(&zombie_lock); 281 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 282 mtx_unlock_spin(&zombie_lock); 283 } 284 285 /* 286 * Release a thread that has exited after cpu_throw(). 287 */ 288 void 289 thread_stash(struct thread *td) 290 { 291 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 292 thread_zombie(td); 293 } 294 295 /* 296 * Reap zombie resources. 297 */ 298 void 299 thread_reap(void) 300 { 301 struct thread *td_first, *td_next; 302 303 /* 304 * Don't even bother to lock if none at this instant, 305 * we really don't care about the next instant.. 306 */ 307 if (!TAILQ_EMPTY(&zombie_threads)) { 308 mtx_lock_spin(&zombie_lock); 309 td_first = TAILQ_FIRST(&zombie_threads); 310 if (td_first) 311 TAILQ_INIT(&zombie_threads); 312 mtx_unlock_spin(&zombie_lock); 313 while (td_first) { 314 td_next = TAILQ_NEXT(td_first, td_slpq); 315 if (td_first->td_ucred) 316 crfree(td_first->td_ucred); 317 thread_free(td_first); 318 td_first = td_next; 319 } 320 } 321 } 322 323 /* 324 * Allocate a thread. 325 */ 326 struct thread * 327 thread_alloc(int pages) 328 { 329 struct thread *td; 330 331 thread_reap(); /* check if any zombies to get */ 332 333 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 334 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 335 if (!vm_thread_new(td, pages)) { 336 uma_zfree(thread_zone, td); 337 return (NULL); 338 } 339 cpu_thread_alloc(td); 340 return (td); 341 } 342 343 int 344 thread_alloc_stack(struct thread *td, int pages) 345 { 346 347 KASSERT(td->td_kstack == 0, 348 ("thread_alloc_stack called on a thread with kstack")); 349 if (!vm_thread_new(td, pages)) 350 return (0); 351 cpu_thread_alloc(td); 352 return (1); 353 } 354 355 /* 356 * Deallocate a thread. 357 */ 358 void 359 thread_free(struct thread *td) 360 { 361 362 lock_profile_thread_exit(td); 363 if (td->td_cpuset) 364 cpuset_rel(td->td_cpuset); 365 td->td_cpuset = NULL; 366 cpu_thread_free(td); 367 if (td->td_kstack != 0) 368 vm_thread_dispose(td); 369 uma_zfree(thread_zone, td); 370 } 371 372 /* 373 * Discard the current thread and exit from its context. 374 * Always called with scheduler locked. 375 * 376 * Because we can't free a thread while we're operating under its context, 377 * push the current thread into our CPU's deadthread holder. This means 378 * we needn't worry about someone else grabbing our context before we 379 * do a cpu_throw(). 380 */ 381 void 382 thread_exit(void) 383 { 384 uint64_t new_switchtime; 385 struct thread *td; 386 struct thread *td2; 387 struct proc *p; 388 int wakeup_swapper; 389 390 td = curthread; 391 p = td->td_proc; 392 393 PROC_SLOCK_ASSERT(p, MA_OWNED); 394 mtx_assert(&Giant, MA_NOTOWNED); 395 396 PROC_LOCK_ASSERT(p, MA_OWNED); 397 KASSERT(p != NULL, ("thread exiting without a process")); 398 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 399 (long)p->p_pid, td->td_name); 400 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 401 402 #ifdef AUDIT 403 AUDIT_SYSCALL_EXIT(0, td); 404 #endif 405 umtx_thread_exit(td); 406 /* 407 * drop FPU & debug register state storage, or any other 408 * architecture specific resources that 409 * would not be on a new untouched process. 410 */ 411 cpu_thread_exit(td); /* XXXSMP */ 412 413 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 414 new_switchtime = cpu_ticks(); 415 p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime)); 416 PCPU_SET(switchtime, new_switchtime); 417 PCPU_SET(switchticks, ticks); 418 PCPU_INC(cnt.v_swtch); 419 /* Save our resource usage in our process. */ 420 td->td_ru.ru_nvcsw++; 421 rucollect(&p->p_ru, &td->td_ru); 422 /* 423 * The last thread is left attached to the process 424 * So that the whole bundle gets recycled. Skip 425 * all this stuff if we never had threads. 426 * EXIT clears all sign of other threads when 427 * it goes to single threading, so the last thread always 428 * takes the short path. 429 */ 430 if (p->p_flag & P_HADTHREADS) { 431 if (p->p_numthreads > 1) { 432 thread_unlink(td); 433 td2 = FIRST_THREAD_IN_PROC(p); 434 sched_exit_thread(td2, td); 435 436 /* 437 * The test below is NOT true if we are the 438 * sole exiting thread. P_STOPPED_SINGLE is unset 439 * in exit1() after it is the only survivor. 440 */ 441 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 442 if (p->p_numthreads == p->p_suspcount) { 443 thread_lock(p->p_singlethread); 444 wakeup_swapper = thread_unsuspend_one( 445 p->p_singlethread); 446 thread_unlock(p->p_singlethread); 447 if (wakeup_swapper) 448 kick_proc0(); 449 } 450 } 451 452 atomic_add_int(&td->td_proc->p_exitthreads, 1); 453 PCPU_SET(deadthread, td); 454 } else { 455 /* 456 * The last thread is exiting.. but not through exit() 457 */ 458 panic ("thread_exit: Last thread exiting on its own"); 459 } 460 } 461 #ifdef HWPMC_HOOKS 462 /* 463 * If this thread is part of a process that is being tracked by hwpmc(4), 464 * inform the module of the thread's impending exit. 465 */ 466 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 467 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 468 #endif 469 PROC_UNLOCK(p); 470 ruxagg(p, td); 471 thread_lock(td); 472 PROC_SUNLOCK(p); 473 td->td_state = TDS_INACTIVE; 474 #ifdef WITNESS 475 witness_thread_exit(td); 476 #endif 477 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 478 sched_throw(td); 479 panic("I'm a teapot!"); 480 /* NOTREACHED */ 481 } 482 483 /* 484 * Do any thread specific cleanups that may be needed in wait() 485 * called with Giant, proc and schedlock not held. 486 */ 487 void 488 thread_wait(struct proc *p) 489 { 490 struct thread *td; 491 492 mtx_assert(&Giant, MA_NOTOWNED); 493 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 494 td = FIRST_THREAD_IN_PROC(p); 495 /* Lock the last thread so we spin until it exits cpu_throw(). */ 496 thread_lock(td); 497 thread_unlock(td); 498 /* Wait for any remaining threads to exit cpu_throw(). */ 499 while (p->p_exitthreads) 500 sched_relinquish(curthread); 501 lock_profile_thread_exit(td); 502 cpuset_rel(td->td_cpuset); 503 td->td_cpuset = NULL; 504 cpu_thread_clean(td); 505 crfree(td->td_ucred); 506 thread_reap(); /* check for zombie threads etc. */ 507 } 508 509 /* 510 * Link a thread to a process. 511 * set up anything that needs to be initialized for it to 512 * be used by the process. 513 */ 514 void 515 thread_link(struct thread *td, struct proc *p) 516 { 517 518 /* 519 * XXX This can't be enabled because it's called for proc0 before 520 * its lock has been created. 521 * PROC_LOCK_ASSERT(p, MA_OWNED); 522 */ 523 td->td_state = TDS_INACTIVE; 524 td->td_proc = p; 525 td->td_flags = TDF_INMEM; 526 527 LIST_INIT(&td->td_contested); 528 LIST_INIT(&td->td_lprof[0]); 529 LIST_INIT(&td->td_lprof[1]); 530 sigqueue_init(&td->td_sigqueue, p); 531 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 532 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 533 p->p_numthreads++; 534 } 535 536 /* 537 * Convert a process with one thread to an unthreaded process. 538 */ 539 void 540 thread_unthread(struct thread *td) 541 { 542 struct proc *p = td->td_proc; 543 544 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 545 p->p_flag &= ~P_HADTHREADS; 546 } 547 548 /* 549 * Called from: 550 * thread_exit() 551 */ 552 void 553 thread_unlink(struct thread *td) 554 { 555 struct proc *p = td->td_proc; 556 557 PROC_LOCK_ASSERT(p, MA_OWNED); 558 TAILQ_REMOVE(&p->p_threads, td, td_plist); 559 p->p_numthreads--; 560 /* could clear a few other things here */ 561 /* Must NOT clear links to proc! */ 562 } 563 564 static int 565 calc_remaining(struct proc *p, int mode) 566 { 567 int remaining; 568 569 if (mode == SINGLE_EXIT) 570 remaining = p->p_numthreads; 571 else if (mode == SINGLE_BOUNDARY) 572 remaining = p->p_numthreads - p->p_boundary_count; 573 else if (mode == SINGLE_NO_EXIT) 574 remaining = p->p_numthreads - p->p_suspcount; 575 else 576 panic("calc_remaining: wrong mode %d", mode); 577 return (remaining); 578 } 579 580 /* 581 * Enforce single-threading. 582 * 583 * Returns 1 if the caller must abort (another thread is waiting to 584 * exit the process or similar). Process is locked! 585 * Returns 0 when you are successfully the only thread running. 586 * A process has successfully single threaded in the suspend mode when 587 * There are no threads in user mode. Threads in the kernel must be 588 * allowed to continue until they get to the user boundary. They may even 589 * copy out their return values and data before suspending. They may however be 590 * accelerated in reaching the user boundary as we will wake up 591 * any sleeping threads that are interruptable. (PCATCH). 592 */ 593 int 594 thread_single(int mode) 595 { 596 struct thread *td; 597 struct thread *td2; 598 struct proc *p; 599 int remaining, wakeup_swapper; 600 601 td = curthread; 602 p = td->td_proc; 603 mtx_assert(&Giant, MA_NOTOWNED); 604 PROC_LOCK_ASSERT(p, MA_OWNED); 605 KASSERT((td != NULL), ("curthread is NULL")); 606 607 if ((p->p_flag & P_HADTHREADS) == 0) 608 return (0); 609 610 /* Is someone already single threading? */ 611 if (p->p_singlethread != NULL && p->p_singlethread != td) 612 return (1); 613 614 if (mode == SINGLE_EXIT) { 615 p->p_flag |= P_SINGLE_EXIT; 616 p->p_flag &= ~P_SINGLE_BOUNDARY; 617 } else { 618 p->p_flag &= ~P_SINGLE_EXIT; 619 if (mode == SINGLE_BOUNDARY) 620 p->p_flag |= P_SINGLE_BOUNDARY; 621 else 622 p->p_flag &= ~P_SINGLE_BOUNDARY; 623 } 624 p->p_flag |= P_STOPPED_SINGLE; 625 PROC_SLOCK(p); 626 p->p_singlethread = td; 627 remaining = calc_remaining(p, mode); 628 while (remaining != 1) { 629 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 630 goto stopme; 631 wakeup_swapper = 0; 632 FOREACH_THREAD_IN_PROC(p, td2) { 633 if (td2 == td) 634 continue; 635 thread_lock(td2); 636 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 637 if (TD_IS_INHIBITED(td2)) { 638 switch (mode) { 639 case SINGLE_EXIT: 640 if (TD_IS_SUSPENDED(td2)) 641 wakeup_swapper |= 642 thread_unsuspend_one(td2); 643 if (TD_ON_SLEEPQ(td2) && 644 (td2->td_flags & TDF_SINTR)) 645 wakeup_swapper |= 646 sleepq_abort(td2, EINTR); 647 break; 648 case SINGLE_BOUNDARY: 649 if (TD_IS_SUSPENDED(td2) && 650 !(td2->td_flags & TDF_BOUNDARY)) 651 wakeup_swapper |= 652 thread_unsuspend_one(td2); 653 if (TD_ON_SLEEPQ(td2) && 654 (td2->td_flags & TDF_SINTR)) 655 wakeup_swapper |= 656 sleepq_abort(td2, ERESTART); 657 break; 658 case SINGLE_NO_EXIT: 659 if (TD_IS_SUSPENDED(td2) && 660 !(td2->td_flags & TDF_BOUNDARY)) 661 wakeup_swapper |= 662 thread_unsuspend_one(td2); 663 if (TD_ON_SLEEPQ(td2) && 664 (td2->td_flags & TDF_SINTR)) 665 wakeup_swapper |= 666 sleepq_abort(td2, ERESTART); 667 break; 668 default: 669 break; 670 } 671 } 672 #ifdef SMP 673 else if (TD_IS_RUNNING(td2) && td != td2) { 674 forward_signal(td2); 675 } 676 #endif 677 thread_unlock(td2); 678 } 679 if (wakeup_swapper) 680 kick_proc0(); 681 remaining = calc_remaining(p, mode); 682 683 /* 684 * Maybe we suspended some threads.. was it enough? 685 */ 686 if (remaining == 1) 687 break; 688 689 stopme: 690 /* 691 * Wake us up when everyone else has suspended. 692 * In the mean time we suspend as well. 693 */ 694 thread_suspend_switch(td); 695 remaining = calc_remaining(p, mode); 696 } 697 if (mode == SINGLE_EXIT) { 698 /* 699 * We have gotten rid of all the other threads and we 700 * are about to either exit or exec. In either case, 701 * we try our utmost to revert to being a non-threaded 702 * process. 703 */ 704 p->p_singlethread = NULL; 705 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 706 thread_unthread(td); 707 } 708 PROC_SUNLOCK(p); 709 return (0); 710 } 711 712 /* 713 * Called in from locations that can safely check to see 714 * whether we have to suspend or at least throttle for a 715 * single-thread event (e.g. fork). 716 * 717 * Such locations include userret(). 718 * If the "return_instead" argument is non zero, the thread must be able to 719 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 720 * 721 * The 'return_instead' argument tells the function if it may do a 722 * thread_exit() or suspend, or whether the caller must abort and back 723 * out instead. 724 * 725 * If the thread that set the single_threading request has set the 726 * P_SINGLE_EXIT bit in the process flags then this call will never return 727 * if 'return_instead' is false, but will exit. 728 * 729 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 730 *---------------+--------------------+--------------------- 731 * 0 | returns 0 | returns 0 or 1 732 * | when ST ends | immediatly 733 *---------------+--------------------+--------------------- 734 * 1 | thread exits | returns 1 735 * | | immediatly 736 * 0 = thread_exit() or suspension ok, 737 * other = return error instead of stopping the thread. 738 * 739 * While a full suspension is under effect, even a single threading 740 * thread would be suspended if it made this call (but it shouldn't). 741 * This call should only be made from places where 742 * thread_exit() would be safe as that may be the outcome unless 743 * return_instead is set. 744 */ 745 int 746 thread_suspend_check(int return_instead) 747 { 748 struct thread *td; 749 struct proc *p; 750 int wakeup_swapper; 751 752 td = curthread; 753 p = td->td_proc; 754 mtx_assert(&Giant, MA_NOTOWNED); 755 PROC_LOCK_ASSERT(p, MA_OWNED); 756 while (P_SHOULDSTOP(p) || 757 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) { 758 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 759 KASSERT(p->p_singlethread != NULL, 760 ("singlethread not set")); 761 /* 762 * The only suspension in action is a 763 * single-threading. Single threader need not stop. 764 * XXX Should be safe to access unlocked 765 * as it can only be set to be true by us. 766 */ 767 if (p->p_singlethread == td) 768 return (0); /* Exempt from stopping. */ 769 } 770 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 771 return (EINTR); 772 773 /* Should we goto user boundary if we didn't come from there? */ 774 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 775 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 776 return (ERESTART); 777 778 /* 779 * If the process is waiting for us to exit, 780 * this thread should just suicide. 781 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 782 */ 783 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 784 PROC_UNLOCK(p); 785 tidhash_remove(td); 786 PROC_LOCK(p); 787 tdsigcleanup(td); 788 PROC_SLOCK(p); 789 thread_stopped(p); 790 thread_exit(); 791 } 792 793 PROC_SLOCK(p); 794 thread_stopped(p); 795 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 796 if (p->p_numthreads == p->p_suspcount + 1) { 797 thread_lock(p->p_singlethread); 798 wakeup_swapper = 799 thread_unsuspend_one(p->p_singlethread); 800 thread_unlock(p->p_singlethread); 801 if (wakeup_swapper) 802 kick_proc0(); 803 } 804 } 805 PROC_UNLOCK(p); 806 thread_lock(td); 807 /* 808 * When a thread suspends, it just 809 * gets taken off all queues. 810 */ 811 thread_suspend_one(td); 812 if (return_instead == 0) { 813 p->p_boundary_count++; 814 td->td_flags |= TDF_BOUNDARY; 815 } 816 PROC_SUNLOCK(p); 817 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 818 if (return_instead == 0) 819 td->td_flags &= ~TDF_BOUNDARY; 820 thread_unlock(td); 821 PROC_LOCK(p); 822 if (return_instead == 0) 823 p->p_boundary_count--; 824 } 825 return (0); 826 } 827 828 void 829 thread_suspend_switch(struct thread *td) 830 { 831 struct proc *p; 832 833 p = td->td_proc; 834 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 835 PROC_LOCK_ASSERT(p, MA_OWNED); 836 PROC_SLOCK_ASSERT(p, MA_OWNED); 837 /* 838 * We implement thread_suspend_one in stages here to avoid 839 * dropping the proc lock while the thread lock is owned. 840 */ 841 thread_stopped(p); 842 p->p_suspcount++; 843 PROC_UNLOCK(p); 844 thread_lock(td); 845 td->td_flags &= ~TDF_NEEDSUSPCHK; 846 TD_SET_SUSPENDED(td); 847 sched_sleep(td, 0); 848 PROC_SUNLOCK(p); 849 DROP_GIANT(); 850 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 851 thread_unlock(td); 852 PICKUP_GIANT(); 853 PROC_LOCK(p); 854 PROC_SLOCK(p); 855 } 856 857 void 858 thread_suspend_one(struct thread *td) 859 { 860 struct proc *p = td->td_proc; 861 862 PROC_SLOCK_ASSERT(p, MA_OWNED); 863 THREAD_LOCK_ASSERT(td, MA_OWNED); 864 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 865 p->p_suspcount++; 866 td->td_flags &= ~TDF_NEEDSUSPCHK; 867 TD_SET_SUSPENDED(td); 868 sched_sleep(td, 0); 869 } 870 871 int 872 thread_unsuspend_one(struct thread *td) 873 { 874 struct proc *p = td->td_proc; 875 876 PROC_SLOCK_ASSERT(p, MA_OWNED); 877 THREAD_LOCK_ASSERT(td, MA_OWNED); 878 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 879 TD_CLR_SUSPENDED(td); 880 p->p_suspcount--; 881 return (setrunnable(td)); 882 } 883 884 /* 885 * Allow all threads blocked by single threading to continue running. 886 */ 887 void 888 thread_unsuspend(struct proc *p) 889 { 890 struct thread *td; 891 int wakeup_swapper; 892 893 PROC_LOCK_ASSERT(p, MA_OWNED); 894 PROC_SLOCK_ASSERT(p, MA_OWNED); 895 wakeup_swapper = 0; 896 if (!P_SHOULDSTOP(p)) { 897 FOREACH_THREAD_IN_PROC(p, td) { 898 thread_lock(td); 899 if (TD_IS_SUSPENDED(td)) { 900 wakeup_swapper |= thread_unsuspend_one(td); 901 } 902 thread_unlock(td); 903 } 904 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 905 (p->p_numthreads == p->p_suspcount)) { 906 /* 907 * Stopping everything also did the job for the single 908 * threading request. Now we've downgraded to single-threaded, 909 * let it continue. 910 */ 911 thread_lock(p->p_singlethread); 912 wakeup_swapper = thread_unsuspend_one(p->p_singlethread); 913 thread_unlock(p->p_singlethread); 914 } 915 if (wakeup_swapper) 916 kick_proc0(); 917 } 918 919 /* 920 * End the single threading mode.. 921 */ 922 void 923 thread_single_end(void) 924 { 925 struct thread *td; 926 struct proc *p; 927 int wakeup_swapper; 928 929 td = curthread; 930 p = td->td_proc; 931 PROC_LOCK_ASSERT(p, MA_OWNED); 932 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 933 PROC_SLOCK(p); 934 p->p_singlethread = NULL; 935 wakeup_swapper = 0; 936 /* 937 * If there are other threads they may now run, 938 * unless of course there is a blanket 'stop order' 939 * on the process. The single threader must be allowed 940 * to continue however as this is a bad place to stop. 941 */ 942 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 943 FOREACH_THREAD_IN_PROC(p, td) { 944 thread_lock(td); 945 if (TD_IS_SUSPENDED(td)) { 946 wakeup_swapper |= thread_unsuspend_one(td); 947 } 948 thread_unlock(td); 949 } 950 } 951 PROC_SUNLOCK(p); 952 if (wakeup_swapper) 953 kick_proc0(); 954 } 955 956 struct thread * 957 thread_find(struct proc *p, lwpid_t tid) 958 { 959 struct thread *td; 960 961 PROC_LOCK_ASSERT(p, MA_OWNED); 962 FOREACH_THREAD_IN_PROC(p, td) { 963 if (td->td_tid == tid) 964 break; 965 } 966 return (td); 967 } 968 969 /* Locate a thread by number; return with proc lock held. */ 970 struct thread * 971 tdfind(lwpid_t tid, pid_t pid) 972 { 973 #define RUN_THRESH 16 974 struct thread *td; 975 int run = 0; 976 977 rw_rlock(&tidhash_lock); 978 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 979 if (td->td_tid == tid) { 980 if (pid != -1 && td->td_proc->p_pid != pid) { 981 td = NULL; 982 break; 983 } 984 PROC_LOCK(td->td_proc); 985 if (td->td_proc->p_state == PRS_NEW) { 986 PROC_UNLOCK(td->td_proc); 987 td = NULL; 988 break; 989 } 990 if (run > RUN_THRESH) { 991 if (rw_try_upgrade(&tidhash_lock)) { 992 LIST_REMOVE(td, td_hash); 993 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 994 td, td_hash); 995 rw_wunlock(&tidhash_lock); 996 return (td); 997 } 998 } 999 break; 1000 } 1001 run++; 1002 } 1003 rw_runlock(&tidhash_lock); 1004 return (td); 1005 } 1006 1007 void 1008 tidhash_add(struct thread *td) 1009 { 1010 rw_wlock(&tidhash_lock); 1011 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1012 rw_wunlock(&tidhash_lock); 1013 } 1014 1015 void 1016 tidhash_remove(struct thread *td) 1017 { 1018 rw_wlock(&tidhash_lock); 1019 LIST_REMOVE(td, td_hash); 1020 rw_wunlock(&tidhash_lock); 1021 } 1022