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_kdtrace.h" 31 #include "opt_hwpmc_hooks.h" 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/kernel.h> 39 #include <sys/lock.h> 40 #include <sys/mutex.h> 41 #include <sys/proc.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, 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_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_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 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 turnstile_free(td->td_turnstile); 226 sleepq_free(td->td_sleepqueue); 227 umtx_thread_fini(td); 228 seltdfini(td); 229 } 230 231 /* 232 * For a newly created process, 233 * link up all the structures and its initial threads etc. 234 * called from: 235 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 236 * proc_dtor() (should go away) 237 * proc_init() 238 */ 239 void 240 proc_linkup0(struct proc *p, struct thread *td) 241 { 242 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 243 proc_linkup(p, td); 244 } 245 246 void 247 proc_linkup(struct proc *p, struct thread *td) 248 { 249 250 sigqueue_init(&p->p_sigqueue, p); 251 p->p_ksi = ksiginfo_alloc(1); 252 if (p->p_ksi != NULL) { 253 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 254 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 255 } 256 LIST_INIT(&p->p_mqnotifier); 257 p->p_numthreads = 0; 258 thread_link(td, p); 259 } 260 261 /* 262 * Initialize global thread allocation resources. 263 */ 264 void 265 threadinit(void) 266 { 267 268 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 269 /* leave one number for thread0 */ 270 tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock); 271 272 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 273 thread_ctor, thread_dtor, thread_init, thread_fini, 274 16 - 1, 0); 275 tidhashtbl = hashinit(maxproc / 2, M_TIDHASH, &tidhash); 276 rw_init(&tidhash_lock, "tidhash"); 277 } 278 279 /* 280 * Place an unused thread on the zombie list. 281 * Use the slpq as that must be unused by now. 282 */ 283 void 284 thread_zombie(struct thread *td) 285 { 286 mtx_lock_spin(&zombie_lock); 287 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 288 mtx_unlock_spin(&zombie_lock); 289 } 290 291 /* 292 * Release a thread that has exited after cpu_throw(). 293 */ 294 void 295 thread_stash(struct thread *td) 296 { 297 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 298 thread_zombie(td); 299 } 300 301 /* 302 * Reap zombie resources. 303 */ 304 void 305 thread_reap(void) 306 { 307 struct thread *td_first, *td_next; 308 309 /* 310 * Don't even bother to lock if none at this instant, 311 * we really don't care about the next instant.. 312 */ 313 if (!TAILQ_EMPTY(&zombie_threads)) { 314 mtx_lock_spin(&zombie_lock); 315 td_first = TAILQ_FIRST(&zombie_threads); 316 if (td_first) 317 TAILQ_INIT(&zombie_threads); 318 mtx_unlock_spin(&zombie_lock); 319 while (td_first) { 320 td_next = TAILQ_NEXT(td_first, td_slpq); 321 if (td_first->td_ucred) 322 crfree(td_first->td_ucred); 323 thread_free(td_first); 324 td_first = td_next; 325 } 326 } 327 } 328 329 /* 330 * Allocate a thread. 331 */ 332 struct thread * 333 thread_alloc(int pages) 334 { 335 struct thread *td; 336 337 thread_reap(); /* check if any zombies to get */ 338 339 td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK); 340 KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack")); 341 if (!vm_thread_new(td, pages)) { 342 uma_zfree(thread_zone, td); 343 return (NULL); 344 } 345 cpu_thread_alloc(td); 346 return (td); 347 } 348 349 int 350 thread_alloc_stack(struct thread *td, int pages) 351 { 352 353 KASSERT(td->td_kstack == 0, 354 ("thread_alloc_stack called on a thread with kstack")); 355 if (!vm_thread_new(td, pages)) 356 return (0); 357 cpu_thread_alloc(td); 358 return (1); 359 } 360 361 /* 362 * Deallocate a thread. 363 */ 364 void 365 thread_free(struct thread *td) 366 { 367 368 lock_profile_thread_exit(td); 369 if (td->td_cpuset) 370 cpuset_rel(td->td_cpuset); 371 td->td_cpuset = NULL; 372 cpu_thread_free(td); 373 if (td->td_kstack != 0) 374 vm_thread_dispose(td); 375 uma_zfree(thread_zone, td); 376 } 377 378 /* 379 * Discard the current thread and exit from its context. 380 * Always called with scheduler locked. 381 * 382 * Because we can't free a thread while we're operating under its context, 383 * push the current thread into our CPU's deadthread holder. This means 384 * we needn't worry about someone else grabbing our context before we 385 * do a cpu_throw(). 386 */ 387 void 388 thread_exit(void) 389 { 390 uint64_t runtime, new_switchtime; 391 struct thread *td; 392 struct thread *td2; 393 struct proc *p; 394 int wakeup_swapper; 395 396 td = curthread; 397 p = td->td_proc; 398 399 PROC_SLOCK_ASSERT(p, MA_OWNED); 400 mtx_assert(&Giant, MA_NOTOWNED); 401 402 PROC_LOCK_ASSERT(p, MA_OWNED); 403 KASSERT(p != NULL, ("thread exiting without a process")); 404 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 405 (long)p->p_pid, td->td_name); 406 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 407 408 #ifdef AUDIT 409 AUDIT_SYSCALL_EXIT(0, td); 410 #endif 411 umtx_thread_exit(td); 412 /* 413 * drop FPU & debug register state storage, or any other 414 * architecture specific resources that 415 * would not be on a new untouched process. 416 */ 417 cpu_thread_exit(td); /* XXXSMP */ 418 419 /* 420 * The last thread is left attached to the process 421 * So that the whole bundle gets recycled. Skip 422 * all this stuff if we never had threads. 423 * EXIT clears all sign of other threads when 424 * it goes to single threading, so the last thread always 425 * takes the short path. 426 */ 427 if (p->p_flag & P_HADTHREADS) { 428 if (p->p_numthreads > 1) { 429 thread_unlink(td); 430 td2 = FIRST_THREAD_IN_PROC(p); 431 sched_exit_thread(td2, td); 432 433 /* 434 * The test below is NOT true if we are the 435 * sole exiting thread. P_STOPPED_SINGLE is unset 436 * in exit1() after it is the only survivor. 437 */ 438 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 439 if (p->p_numthreads == p->p_suspcount) { 440 thread_lock(p->p_singlethread); 441 wakeup_swapper = thread_unsuspend_one( 442 p->p_singlethread); 443 thread_unlock(p->p_singlethread); 444 if (wakeup_swapper) 445 kick_proc0(); 446 } 447 } 448 449 atomic_add_int(&td->td_proc->p_exitthreads, 1); 450 PCPU_SET(deadthread, td); 451 } else { 452 /* 453 * The last thread is exiting.. but not through exit() 454 */ 455 panic ("thread_exit: Last thread exiting on its own"); 456 } 457 } 458 #ifdef HWPMC_HOOKS 459 /* 460 * If this thread is part of a process that is being tracked by hwpmc(4), 461 * inform the module of the thread's impending exit. 462 */ 463 if (PMC_PROC_IS_USING_PMCS(td->td_proc)) 464 PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT); 465 #endif 466 PROC_UNLOCK(p); 467 468 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 469 new_switchtime = cpu_ticks(); 470 runtime = new_switchtime - PCPU_GET(switchtime); 471 td->td_runtime += runtime; 472 td->td_incruntime += runtime; 473 PCPU_SET(switchtime, new_switchtime); 474 PCPU_SET(switchticks, ticks); 475 PCPU_INC(cnt.v_swtch); 476 477 /* Save our resource usage in our process. */ 478 td->td_ru.ru_nvcsw++; 479 ruxagg(p, td); 480 rucollect(&p->p_ru, &td->td_ru); 481 482 thread_lock(td); 483 PROC_SUNLOCK(p); 484 td->td_state = TDS_INACTIVE; 485 #ifdef WITNESS 486 witness_thread_exit(td); 487 #endif 488 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 489 sched_throw(td); 490 panic("I'm a teapot!"); 491 /* NOTREACHED */ 492 } 493 494 /* 495 * Do any thread specific cleanups that may be needed in wait() 496 * called with Giant, proc and schedlock not held. 497 */ 498 void 499 thread_wait(struct proc *p) 500 { 501 struct thread *td; 502 503 mtx_assert(&Giant, MA_NOTOWNED); 504 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 505 td = FIRST_THREAD_IN_PROC(p); 506 /* Lock the last thread so we spin until it exits cpu_throw(). */ 507 thread_lock(td); 508 thread_unlock(td); 509 /* Wait for any remaining threads to exit cpu_throw(). */ 510 while (p->p_exitthreads) 511 sched_relinquish(curthread); 512 lock_profile_thread_exit(td); 513 cpuset_rel(td->td_cpuset); 514 td->td_cpuset = NULL; 515 cpu_thread_clean(td); 516 crfree(td->td_ucred); 517 thread_reap(); /* check for zombie threads etc. */ 518 } 519 520 /* 521 * Link a thread to a process. 522 * set up anything that needs to be initialized for it to 523 * be used by the process. 524 */ 525 void 526 thread_link(struct thread *td, struct proc *p) 527 { 528 529 /* 530 * XXX This can't be enabled because it's called for proc0 before 531 * its lock has been created. 532 * PROC_LOCK_ASSERT(p, MA_OWNED); 533 */ 534 td->td_state = TDS_INACTIVE; 535 td->td_proc = p; 536 td->td_flags = TDF_INMEM; 537 538 LIST_INIT(&td->td_contested); 539 LIST_INIT(&td->td_lprof[0]); 540 LIST_INIT(&td->td_lprof[1]); 541 sigqueue_init(&td->td_sigqueue, p); 542 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 543 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 544 p->p_numthreads++; 545 } 546 547 /* 548 * Convert a process with one thread to an unthreaded process. 549 */ 550 void 551 thread_unthread(struct thread *td) 552 { 553 struct proc *p = td->td_proc; 554 555 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 556 p->p_flag &= ~P_HADTHREADS; 557 } 558 559 /* 560 * Called from: 561 * thread_exit() 562 */ 563 void 564 thread_unlink(struct thread *td) 565 { 566 struct proc *p = td->td_proc; 567 568 PROC_LOCK_ASSERT(p, MA_OWNED); 569 TAILQ_REMOVE(&p->p_threads, td, td_plist); 570 p->p_numthreads--; 571 /* could clear a few other things here */ 572 /* Must NOT clear links to proc! */ 573 } 574 575 static int 576 calc_remaining(struct proc *p, int mode) 577 { 578 int remaining; 579 580 PROC_LOCK_ASSERT(p, MA_OWNED); 581 PROC_SLOCK_ASSERT(p, MA_OWNED); 582 if (mode == SINGLE_EXIT) 583 remaining = p->p_numthreads; 584 else if (mode == SINGLE_BOUNDARY) 585 remaining = p->p_numthreads - p->p_boundary_count; 586 else if (mode == SINGLE_NO_EXIT) 587 remaining = p->p_numthreads - p->p_suspcount; 588 else 589 panic("calc_remaining: wrong mode %d", mode); 590 return (remaining); 591 } 592 593 /* 594 * Enforce single-threading. 595 * 596 * Returns 1 if the caller must abort (another thread is waiting to 597 * exit the process or similar). Process is locked! 598 * Returns 0 when you are successfully the only thread running. 599 * A process has successfully single threaded in the suspend mode when 600 * There are no threads in user mode. Threads in the kernel must be 601 * allowed to continue until they get to the user boundary. They may even 602 * copy out their return values and data before suspending. They may however be 603 * accelerated in reaching the user boundary as we will wake up 604 * any sleeping threads that are interruptable. (PCATCH). 605 */ 606 int 607 thread_single(int mode) 608 { 609 struct thread *td; 610 struct thread *td2; 611 struct proc *p; 612 int remaining, wakeup_swapper; 613 614 td = curthread; 615 p = td->td_proc; 616 mtx_assert(&Giant, MA_NOTOWNED); 617 PROC_LOCK_ASSERT(p, MA_OWNED); 618 KASSERT((td != NULL), ("curthread is NULL")); 619 620 if ((p->p_flag & P_HADTHREADS) == 0) 621 return (0); 622 623 /* Is someone already single threading? */ 624 if (p->p_singlethread != NULL && p->p_singlethread != td) 625 return (1); 626 627 if (mode == SINGLE_EXIT) { 628 p->p_flag |= P_SINGLE_EXIT; 629 p->p_flag &= ~P_SINGLE_BOUNDARY; 630 } else { 631 p->p_flag &= ~P_SINGLE_EXIT; 632 if (mode == SINGLE_BOUNDARY) 633 p->p_flag |= P_SINGLE_BOUNDARY; 634 else 635 p->p_flag &= ~P_SINGLE_BOUNDARY; 636 } 637 p->p_flag |= P_STOPPED_SINGLE; 638 PROC_SLOCK(p); 639 p->p_singlethread = td; 640 remaining = calc_remaining(p, mode); 641 while (remaining != 1) { 642 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 643 goto stopme; 644 wakeup_swapper = 0; 645 FOREACH_THREAD_IN_PROC(p, td2) { 646 if (td2 == td) 647 continue; 648 thread_lock(td2); 649 td2->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK; 650 if (TD_IS_INHIBITED(td2)) { 651 switch (mode) { 652 case SINGLE_EXIT: 653 if (TD_IS_SUSPENDED(td2)) 654 wakeup_swapper |= 655 thread_unsuspend_one(td2); 656 if (TD_ON_SLEEPQ(td2) && 657 (td2->td_flags & TDF_SINTR)) 658 wakeup_swapper |= 659 sleepq_abort(td2, EINTR); 660 break; 661 case SINGLE_BOUNDARY: 662 if (TD_IS_SUSPENDED(td2) && 663 !(td2->td_flags & TDF_BOUNDARY)) 664 wakeup_swapper |= 665 thread_unsuspend_one(td2); 666 if (TD_ON_SLEEPQ(td2) && 667 (td2->td_flags & TDF_SINTR)) 668 wakeup_swapper |= 669 sleepq_abort(td2, ERESTART); 670 break; 671 case SINGLE_NO_EXIT: 672 if (TD_IS_SUSPENDED(td2) && 673 !(td2->td_flags & TDF_BOUNDARY)) 674 wakeup_swapper |= 675 thread_unsuspend_one(td2); 676 if (TD_ON_SLEEPQ(td2) && 677 (td2->td_flags & TDF_SINTR)) 678 wakeup_swapper |= 679 sleepq_abort(td2, ERESTART); 680 break; 681 default: 682 break; 683 } 684 } 685 #ifdef SMP 686 else if (TD_IS_RUNNING(td2) && td != td2) { 687 forward_signal(td2); 688 } 689 #endif 690 thread_unlock(td2); 691 } 692 if (wakeup_swapper) 693 kick_proc0(); 694 remaining = calc_remaining(p, mode); 695 696 /* 697 * Maybe we suspended some threads.. was it enough? 698 */ 699 if (remaining == 1) 700 break; 701 702 stopme: 703 /* 704 * Wake us up when everyone else has suspended. 705 * In the mean time we suspend as well. 706 */ 707 thread_suspend_switch(td); 708 remaining = calc_remaining(p, mode); 709 } 710 if (mode == SINGLE_EXIT) { 711 /* 712 * We have gotten rid of all the other threads and we 713 * are about to either exit or exec. In either case, 714 * we try our utmost to revert to being a non-threaded 715 * process. 716 */ 717 p->p_singlethread = NULL; 718 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 719 thread_unthread(td); 720 } 721 PROC_SUNLOCK(p); 722 return (0); 723 } 724 725 /* 726 * Called in from locations that can safely check to see 727 * whether we have to suspend or at least throttle for a 728 * single-thread event (e.g. fork). 729 * 730 * Such locations include userret(). 731 * If the "return_instead" argument is non zero, the thread must be able to 732 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 733 * 734 * The 'return_instead' argument tells the function if it may do a 735 * thread_exit() or suspend, or whether the caller must abort and back 736 * out instead. 737 * 738 * If the thread that set the single_threading request has set the 739 * P_SINGLE_EXIT bit in the process flags then this call will never return 740 * if 'return_instead' is false, but will exit. 741 * 742 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 743 *---------------+--------------------+--------------------- 744 * 0 | returns 0 | returns 0 or 1 745 * | when ST ends | immediatly 746 *---------------+--------------------+--------------------- 747 * 1 | thread exits | returns 1 748 * | | immediatly 749 * 0 = thread_exit() or suspension ok, 750 * other = return error instead of stopping the thread. 751 * 752 * While a full suspension is under effect, even a single threading 753 * thread would be suspended if it made this call (but it shouldn't). 754 * This call should only be made from places where 755 * thread_exit() would be safe as that may be the outcome unless 756 * return_instead is set. 757 */ 758 int 759 thread_suspend_check(int return_instead) 760 { 761 struct thread *td; 762 struct proc *p; 763 int wakeup_swapper; 764 765 td = curthread; 766 p = td->td_proc; 767 mtx_assert(&Giant, MA_NOTOWNED); 768 PROC_LOCK_ASSERT(p, MA_OWNED); 769 while (P_SHOULDSTOP(p) || 770 ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) { 771 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 772 KASSERT(p->p_singlethread != NULL, 773 ("singlethread not set")); 774 /* 775 * The only suspension in action is a 776 * single-threading. Single threader need not stop. 777 * XXX Should be safe to access unlocked 778 * as it can only be set to be true by us. 779 */ 780 if (p->p_singlethread == td) 781 return (0); /* Exempt from stopping. */ 782 } 783 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 784 return (EINTR); 785 786 /* Should we goto user boundary if we didn't come from there? */ 787 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 788 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 789 return (ERESTART); 790 791 /* 792 * If the process is waiting for us to exit, 793 * this thread should just suicide. 794 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 795 */ 796 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 797 PROC_UNLOCK(p); 798 tidhash_remove(td); 799 PROC_LOCK(p); 800 tdsigcleanup(td); 801 PROC_SLOCK(p); 802 thread_stopped(p); 803 thread_exit(); 804 } 805 806 PROC_SLOCK(p); 807 thread_stopped(p); 808 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 809 if (p->p_numthreads == p->p_suspcount + 1) { 810 thread_lock(p->p_singlethread); 811 wakeup_swapper = 812 thread_unsuspend_one(p->p_singlethread); 813 thread_unlock(p->p_singlethread); 814 if (wakeup_swapper) 815 kick_proc0(); 816 } 817 } 818 PROC_UNLOCK(p); 819 thread_lock(td); 820 /* 821 * When a thread suspends, it just 822 * gets taken off all queues. 823 */ 824 thread_suspend_one(td); 825 if (return_instead == 0) { 826 p->p_boundary_count++; 827 td->td_flags |= TDF_BOUNDARY; 828 } 829 PROC_SUNLOCK(p); 830 mi_switch(SW_INVOL | SWT_SUSPEND, NULL); 831 if (return_instead == 0) 832 td->td_flags &= ~TDF_BOUNDARY; 833 thread_unlock(td); 834 PROC_LOCK(p); 835 if (return_instead == 0) { 836 PROC_SLOCK(p); 837 p->p_boundary_count--; 838 PROC_SUNLOCK(p); 839 } 840 } 841 return (0); 842 } 843 844 void 845 thread_suspend_switch(struct thread *td) 846 { 847 struct proc *p; 848 849 p = td->td_proc; 850 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 851 PROC_LOCK_ASSERT(p, MA_OWNED); 852 PROC_SLOCK_ASSERT(p, MA_OWNED); 853 /* 854 * We implement thread_suspend_one in stages here to avoid 855 * dropping the proc lock while the thread lock is owned. 856 */ 857 thread_stopped(p); 858 p->p_suspcount++; 859 PROC_UNLOCK(p); 860 thread_lock(td); 861 td->td_flags &= ~TDF_NEEDSUSPCHK; 862 TD_SET_SUSPENDED(td); 863 sched_sleep(td, 0); 864 PROC_SUNLOCK(p); 865 DROP_GIANT(); 866 mi_switch(SW_VOL | SWT_SUSPEND, NULL); 867 thread_unlock(td); 868 PICKUP_GIANT(); 869 PROC_LOCK(p); 870 PROC_SLOCK(p); 871 } 872 873 void 874 thread_suspend_one(struct thread *td) 875 { 876 struct proc *p = td->td_proc; 877 878 PROC_SLOCK_ASSERT(p, MA_OWNED); 879 THREAD_LOCK_ASSERT(td, MA_OWNED); 880 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 881 p->p_suspcount++; 882 td->td_flags &= ~TDF_NEEDSUSPCHK; 883 TD_SET_SUSPENDED(td); 884 sched_sleep(td, 0); 885 } 886 887 int 888 thread_unsuspend_one(struct thread *td) 889 { 890 struct proc *p = td->td_proc; 891 892 PROC_SLOCK_ASSERT(p, MA_OWNED); 893 THREAD_LOCK_ASSERT(td, MA_OWNED); 894 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 895 TD_CLR_SUSPENDED(td); 896 p->p_suspcount--; 897 return (setrunnable(td)); 898 } 899 900 /* 901 * Allow all threads blocked by single threading to continue running. 902 */ 903 void 904 thread_unsuspend(struct proc *p) 905 { 906 struct thread *td; 907 int wakeup_swapper; 908 909 PROC_LOCK_ASSERT(p, MA_OWNED); 910 PROC_SLOCK_ASSERT(p, MA_OWNED); 911 wakeup_swapper = 0; 912 if (!P_SHOULDSTOP(p)) { 913 FOREACH_THREAD_IN_PROC(p, td) { 914 thread_lock(td); 915 if (TD_IS_SUSPENDED(td)) { 916 wakeup_swapper |= thread_unsuspend_one(td); 917 } 918 thread_unlock(td); 919 } 920 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 921 (p->p_numthreads == p->p_suspcount)) { 922 /* 923 * Stopping everything also did the job for the single 924 * threading request. Now we've downgraded to single-threaded, 925 * let it continue. 926 */ 927 thread_lock(p->p_singlethread); 928 wakeup_swapper = thread_unsuspend_one(p->p_singlethread); 929 thread_unlock(p->p_singlethread); 930 } 931 if (wakeup_swapper) 932 kick_proc0(); 933 } 934 935 /* 936 * End the single threading mode.. 937 */ 938 void 939 thread_single_end(void) 940 { 941 struct thread *td; 942 struct proc *p; 943 int wakeup_swapper; 944 945 td = curthread; 946 p = td->td_proc; 947 PROC_LOCK_ASSERT(p, MA_OWNED); 948 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 949 PROC_SLOCK(p); 950 p->p_singlethread = NULL; 951 wakeup_swapper = 0; 952 /* 953 * If there are other threads they may now run, 954 * unless of course there is a blanket 'stop order' 955 * on the process. The single threader must be allowed 956 * to continue however as this is a bad place to stop. 957 */ 958 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 959 FOREACH_THREAD_IN_PROC(p, td) { 960 thread_lock(td); 961 if (TD_IS_SUSPENDED(td)) { 962 wakeup_swapper |= thread_unsuspend_one(td); 963 } 964 thread_unlock(td); 965 } 966 } 967 PROC_SUNLOCK(p); 968 if (wakeup_swapper) 969 kick_proc0(); 970 } 971 972 struct thread * 973 thread_find(struct proc *p, lwpid_t tid) 974 { 975 struct thread *td; 976 977 PROC_LOCK_ASSERT(p, MA_OWNED); 978 FOREACH_THREAD_IN_PROC(p, td) { 979 if (td->td_tid == tid) 980 break; 981 } 982 return (td); 983 } 984 985 /* Locate a thread by number; return with proc lock held. */ 986 struct thread * 987 tdfind(lwpid_t tid, pid_t pid) 988 { 989 #define RUN_THRESH 16 990 struct thread *td; 991 int run = 0; 992 993 rw_rlock(&tidhash_lock); 994 LIST_FOREACH(td, TIDHASH(tid), td_hash) { 995 if (td->td_tid == tid) { 996 if (pid != -1 && td->td_proc->p_pid != pid) { 997 td = NULL; 998 break; 999 } 1000 PROC_LOCK(td->td_proc); 1001 if (td->td_proc->p_state == PRS_NEW) { 1002 PROC_UNLOCK(td->td_proc); 1003 td = NULL; 1004 break; 1005 } 1006 if (run > RUN_THRESH) { 1007 if (rw_try_upgrade(&tidhash_lock)) { 1008 LIST_REMOVE(td, td_hash); 1009 LIST_INSERT_HEAD(TIDHASH(td->td_tid), 1010 td, td_hash); 1011 rw_wunlock(&tidhash_lock); 1012 return (td); 1013 } 1014 } 1015 break; 1016 } 1017 run++; 1018 } 1019 rw_runlock(&tidhash_lock); 1020 return (td); 1021 } 1022 1023 void 1024 tidhash_add(struct thread *td) 1025 { 1026 rw_wlock(&tidhash_lock); 1027 LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash); 1028 rw_wunlock(&tidhash_lock); 1029 } 1030 1031 void 1032 tidhash_remove(struct thread *td) 1033 { 1034 rw_wlock(&tidhash_lock); 1035 LIST_REMOVE(td, td_hash); 1036 rw_wunlock(&tidhash_lock); 1037 } 1038