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 <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/kernel.h> 35 #include <sys/lock.h> 36 #include <sys/mutex.h> 37 #include <sys/proc.h> 38 #include <sys/resourcevar.h> 39 #include <sys/smp.h> 40 #include <sys/sysctl.h> 41 #include <sys/sched.h> 42 #include <sys/sleepqueue.h> 43 #include <sys/turnstile.h> 44 #include <sys/ktr.h> 45 #include <sys/umtx.h> 46 47 #include <security/audit/audit.h> 48 49 #include <vm/vm.h> 50 #include <vm/vm_extern.h> 51 #include <vm/uma.h> 52 53 /* 54 * thread related storage. 55 */ 56 static uma_zone_t thread_zone; 57 58 SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation"); 59 60 int max_threads_per_proc = 1500; 61 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW, 62 &max_threads_per_proc, 0, "Limit on threads per proc"); 63 64 int max_threads_hits; 65 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD, 66 &max_threads_hits, 0, ""); 67 68 #ifdef KSE 69 int virtual_cpu; 70 71 #endif 72 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 73 struct mtx kse_zombie_lock; 74 MTX_SYSINIT(kse_zombie_lock, &kse_zombie_lock, "kse zombie lock", MTX_SPIN); 75 76 #ifdef KSE 77 static int 78 sysctl_kse_virtual_cpu(SYSCTL_HANDLER_ARGS) 79 { 80 int error, new_val; 81 int def_val; 82 83 def_val = mp_ncpus; 84 if (virtual_cpu == 0) 85 new_val = def_val; 86 else 87 new_val = virtual_cpu; 88 error = sysctl_handle_int(oidp, &new_val, 0, req); 89 if (error != 0 || req->newptr == NULL) 90 return (error); 91 if (new_val < 0) 92 return (EINVAL); 93 virtual_cpu = new_val; 94 return (0); 95 } 96 97 /* DEBUG ONLY */ 98 SYSCTL_PROC(_kern_threads, OID_AUTO, virtual_cpu, CTLTYPE_INT|CTLFLAG_RW, 99 0, sizeof(virtual_cpu), sysctl_kse_virtual_cpu, "I", 100 "debug virtual cpus"); 101 #endif 102 103 struct mtx tid_lock; 104 static struct unrhdr *tid_unrhdr; 105 106 /* 107 * Prepare a thread for use. 108 */ 109 static int 110 thread_ctor(void *mem, int size, void *arg, int flags) 111 { 112 struct thread *td; 113 114 td = (struct thread *)mem; 115 td->td_state = TDS_INACTIVE; 116 td->td_oncpu = NOCPU; 117 118 td->td_tid = alloc_unr(tid_unrhdr); 119 td->td_syscalls = 0; 120 121 /* 122 * Note that td_critnest begins life as 1 because the thread is not 123 * running and is thereby implicitly waiting to be on the receiving 124 * end of a context switch. A context switch must occur inside a 125 * critical section, and in fact, includes hand-off of the sched_lock. 126 * After a context switch to a newly created thread, it will release 127 * sched_lock for the first time, and its td_critnest will hit 0 for 128 * the first time. This happens on the far end of a context switch, 129 * and when it context switches away from itself, it will in fact go 130 * back into a critical section, and hand off the sched lock to the 131 * next thread. 132 */ 133 td->td_critnest = 1; 134 135 #ifdef AUDIT 136 audit_thread_alloc(td); 137 #endif 138 umtx_thread_alloc(td); 139 return (0); 140 } 141 142 /* 143 * Reclaim a thread after use. 144 */ 145 static void 146 thread_dtor(void *mem, int size, void *arg) 147 { 148 struct thread *td; 149 150 td = (struct thread *)mem; 151 152 #ifdef INVARIANTS 153 /* Verify that this thread is in a safe state to free. */ 154 switch (td->td_state) { 155 case TDS_INHIBITED: 156 case TDS_RUNNING: 157 case TDS_CAN_RUN: 158 case TDS_RUNQ: 159 /* 160 * We must never unlink a thread that is in one of 161 * these states, because it is currently active. 162 */ 163 panic("bad state for thread unlinking"); 164 /* NOTREACHED */ 165 case TDS_INACTIVE: 166 break; 167 default: 168 panic("bad thread state"); 169 /* NOTREACHED */ 170 } 171 #endif 172 #ifdef AUDIT 173 audit_thread_free(td); 174 #endif 175 free_unr(tid_unrhdr, td->td_tid); 176 sched_newthread(td); 177 } 178 179 /* 180 * Initialize type-stable parts of a thread (when newly created). 181 */ 182 static int 183 thread_init(void *mem, int size, int flags) 184 { 185 struct thread *td; 186 187 td = (struct thread *)mem; 188 189 vm_thread_new(td, 0); 190 cpu_thread_setup(td); 191 td->td_sleepqueue = sleepq_alloc(); 192 td->td_turnstile = turnstile_alloc(); 193 td->td_sched = (struct td_sched *)&td[1]; 194 sched_newthread(td); 195 umtx_thread_init(td); 196 return (0); 197 } 198 199 /* 200 * Tear down type-stable parts of a thread (just before being discarded). 201 */ 202 static void 203 thread_fini(void *mem, int size) 204 { 205 struct thread *td; 206 207 td = (struct thread *)mem; 208 turnstile_free(td->td_turnstile); 209 sleepq_free(td->td_sleepqueue); 210 umtx_thread_fini(td); 211 vm_thread_dispose(td); 212 } 213 214 /* 215 * For a newly created process, 216 * link up all the structures and its initial threads etc. 217 * called from: 218 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 219 * proc_dtor() (should go away) 220 * proc_init() 221 */ 222 void 223 proc_linkup(struct proc *p, struct thread *td) 224 { 225 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 226 TAILQ_INIT(&p->p_upcalls); /* upcall list */ 227 sigqueue_init(&p->p_sigqueue, p); 228 p->p_ksi = ksiginfo_alloc(1); 229 if (p->p_ksi != NULL) { 230 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 231 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 232 } 233 LIST_INIT(&p->p_mqnotifier); 234 p->p_numthreads = 0; 235 thread_link(td, p); 236 } 237 238 /* 239 * Initialize global thread allocation resources. 240 */ 241 void 242 threadinit(void) 243 { 244 245 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 246 tid_unrhdr = new_unrhdr(PID_MAX + 1, INT_MAX, &tid_lock); 247 248 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 249 thread_ctor, thread_dtor, thread_init, thread_fini, 250 16 - 1, 0); 251 #ifdef KSE 252 kseinit(); /* set up kse specific stuff e.g. upcall zone*/ 253 #endif 254 } 255 256 /* 257 * Stash an embarasingly extra thread into the zombie thread queue. 258 * Use the slpq as that must be unused by now. 259 */ 260 void 261 thread_stash(struct thread *td) 262 { 263 mtx_lock_spin(&kse_zombie_lock); 264 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 265 mtx_unlock_spin(&kse_zombie_lock); 266 } 267 268 /* 269 * Reap zombie kse resource. 270 */ 271 void 272 thread_reap(void) 273 { 274 struct thread *td_first, *td_next; 275 276 /* 277 * Don't even bother to lock if none at this instant, 278 * we really don't care about the next instant.. 279 */ 280 if (!TAILQ_EMPTY(&zombie_threads)) { 281 mtx_lock_spin(&kse_zombie_lock); 282 td_first = TAILQ_FIRST(&zombie_threads); 283 if (td_first) 284 TAILQ_INIT(&zombie_threads); 285 mtx_unlock_spin(&kse_zombie_lock); 286 while (td_first) { 287 td_next = TAILQ_NEXT(td_first, td_slpq); 288 if (td_first->td_ucred) 289 crfree(td_first->td_ucred); 290 thread_free(td_first); 291 td_first = td_next; 292 } 293 } 294 } 295 296 /* 297 * Allocate a thread. 298 */ 299 struct thread * 300 thread_alloc(void) 301 { 302 303 thread_reap(); /* check if any zombies to get */ 304 return (uma_zalloc(thread_zone, M_WAITOK)); 305 } 306 307 308 /* 309 * Deallocate a thread. 310 */ 311 void 312 thread_free(struct thread *td) 313 { 314 315 cpu_thread_clean(td); 316 uma_zfree(thread_zone, td); 317 } 318 319 /* 320 * Discard the current thread and exit from its context. 321 * Always called with scheduler locked. 322 * 323 * Because we can't free a thread while we're operating under its context, 324 * push the current thread into our CPU's deadthread holder. This means 325 * we needn't worry about someone else grabbing our context before we 326 * do a cpu_throw(). This may not be needed now as we are under schedlock. 327 * Maybe we can just do a thread_stash() as thr_exit1 does. 328 */ 329 /* XXX 330 * libthr expects its thread exit to return for the last 331 * thread, meaning that the program is back to non-threaded 332 * mode I guess. Because we do this (cpu_throw) unconditionally 333 * here, they have their own version of it. (thr_exit1()) 334 * that doesn't do it all if this was the last thread. 335 * It is also called from thread_suspend_check(). 336 * Of course in the end, they end up coming here through exit1 337 * anyhow.. After fixing 'thr' to play by the rules we should be able 338 * to merge these two functions together. 339 * 340 * called from: 341 * exit1() 342 * kse_exit() 343 * thr_exit() 344 * ifdef KSE 345 * thread_user_enter() 346 * thread_userret() 347 * endif 348 * thread_suspend_check() 349 */ 350 void 351 thread_exit(void) 352 { 353 uint64_t new_switchtime; 354 struct thread *td; 355 struct proc *p; 356 357 td = curthread; 358 p = td->td_proc; 359 360 mtx_assert(&sched_lock, MA_OWNED); 361 mtx_assert(&Giant, MA_NOTOWNED); 362 PROC_LOCK_ASSERT(p, MA_OWNED); 363 KASSERT(p != NULL, ("thread exiting without a process")); 364 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 365 (long)p->p_pid, p->p_comm); 366 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 367 368 #ifdef AUDIT 369 AUDIT_SYSCALL_EXIT(0, td); 370 #endif 371 372 #ifdef KSE 373 if (td->td_standin != NULL) { 374 /* 375 * Note that we don't need to free the cred here as it 376 * is done in thread_reap(). 377 */ 378 thread_stash(td->td_standin); 379 td->td_standin = NULL; 380 } 381 #endif 382 383 umtx_thread_exit(td); 384 385 /* 386 * drop FPU & debug register state storage, or any other 387 * architecture specific resources that 388 * would not be on a new untouched process. 389 */ 390 cpu_thread_exit(td); /* XXXSMP */ 391 392 #ifdef KSE 393 /* 394 * The thread is exiting. scheduler can release its stuff 395 * and collect stats etc. 396 * XXX this is not very right, since PROC_UNLOCK may still 397 * need scheduler stuff. 398 */ 399 sched_thread_exit(td); 400 #endif 401 402 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 403 new_switchtime = cpu_ticks(); 404 p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime)); 405 p->p_rux.rux_uticks += td->td_uticks; 406 p->p_rux.rux_sticks += td->td_sticks; 407 p->p_rux.rux_iticks += td->td_iticks; 408 PCPU_SET(switchtime, new_switchtime); 409 PCPU_SET(switchticks, ticks); 410 cnt.v_swtch++; 411 412 /* Add our usage into the usage of all our children. */ 413 if (p->p_numthreads == 1) 414 ruadd(p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux); 415 416 /* 417 * The last thread is left attached to the process 418 * So that the whole bundle gets recycled. Skip 419 * all this stuff if we never had threads. 420 * EXIT clears all sign of other threads when 421 * it goes to single threading, so the last thread always 422 * takes the short path. 423 */ 424 if (p->p_flag & P_HADTHREADS) { 425 if (p->p_numthreads > 1) { 426 thread_unlink(td); 427 428 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 429 430 /* 431 * The test below is NOT true if we are the 432 * sole exiting thread. P_STOPPED_SNGL is unset 433 * in exit1() after it is the only survivor. 434 */ 435 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 436 if (p->p_numthreads == p->p_suspcount) { 437 thread_unsuspend_one(p->p_singlethread); 438 } 439 } 440 441 #ifdef KSE 442 /* 443 * Because each upcall structure has an owner thread, 444 * owner thread exits only when process is in exiting 445 * state, so upcall to userland is no longer needed, 446 * deleting upcall structure is safe here. 447 * So when all threads in a group is exited, all upcalls 448 * in the group should be automatically freed. 449 * XXXKSE This is a KSE thing and should be exported 450 * there somehow. 451 */ 452 upcall_remove(td); 453 #endif 454 455 PROC_UNLOCK(p); 456 PCPU_SET(deadthread, td); 457 } else { 458 /* 459 * The last thread is exiting.. but not through exit() 460 * what should we do? 461 * Theoretically this can't happen 462 * exit1() - clears threading flags before coming here 463 * kse_exit() - treats last thread specially 464 * thr_exit() - treats last thread specially 465 * ifdef KSE 466 * thread_user_enter() - only if more exist 467 * thread_userret() - only if more exist 468 * endif 469 * thread_suspend_check() - only if more exist 470 */ 471 panic ("thread_exit: Last thread exiting on its own"); 472 } 473 } else { 474 /* 475 * non threaded process comes here. 476 * This includes an EX threaded process that is coming 477 * here via exit1(). (exit1 dethreads the proc first). 478 */ 479 PROC_UNLOCK(p); 480 } 481 td->td_state = TDS_INACTIVE; 482 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 483 cpu_throw(td, choosethread()); 484 panic("I'm a teapot!"); 485 /* NOTREACHED */ 486 } 487 488 /* 489 * Do any thread specific cleanups that may be needed in wait() 490 * called with Giant, proc and schedlock not held. 491 */ 492 void 493 thread_wait(struct proc *p) 494 { 495 struct thread *td; 496 497 mtx_assert(&Giant, MA_NOTOWNED); 498 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 499 FOREACH_THREAD_IN_PROC(p, td) { 500 #ifdef KSE 501 if (td->td_standin != NULL) { 502 if (td->td_standin->td_ucred != NULL) { 503 crfree(td->td_standin->td_ucred); 504 td->td_standin->td_ucred = NULL; 505 } 506 thread_free(td->td_standin); 507 td->td_standin = NULL; 508 } 509 #endif 510 cpu_thread_clean(td); 511 crfree(td->td_ucred); 512 } 513 thread_reap(); /* check for zombie threads etc. */ 514 } 515 516 /* 517 * Link a thread to a process. 518 * set up anything that needs to be initialized for it to 519 * be used by the process. 520 * 521 * Note that we do not link to the proc's ucred here. 522 * The thread is linked as if running but no KSE assigned. 523 * Called from: 524 * proc_linkup() 525 * thread_schedule_upcall() 526 * thr_create() 527 */ 528 void 529 thread_link(struct thread *td, struct proc *p) 530 { 531 532 td->td_state = TDS_INACTIVE; 533 td->td_proc = p; 534 td->td_flags = 0; 535 536 LIST_INIT(&td->td_contested); 537 sigqueue_init(&td->td_sigqueue, p); 538 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 539 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 540 p->p_numthreads++; 541 } 542 543 /* 544 * Convert a process with one thread to an unthreaded process. 545 * Called from: 546 * thread_single(exit) (called from execve and exit) 547 * kse_exit() XXX may need cleaning up wrt KSE stuff 548 */ 549 void 550 thread_unthread(struct thread *td) 551 { 552 struct proc *p = td->td_proc; 553 554 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 555 #ifdef KSE 556 upcall_remove(td); 557 p->p_flag &= ~(P_SA|P_HADTHREADS); 558 td->td_mailbox = NULL; 559 td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND); 560 if (td->td_standin != NULL) { 561 thread_stash(td->td_standin); 562 td->td_standin = NULL; 563 } 564 sched_set_concurrency(p, 1); 565 #else 566 p->p_flag &= ~P_HADTHREADS; 567 #endif 568 } 569 570 /* 571 * Called from: 572 * thread_exit() 573 */ 574 void 575 thread_unlink(struct thread *td) 576 { 577 struct proc *p = td->td_proc; 578 579 mtx_assert(&sched_lock, MA_OWNED); 580 TAILQ_REMOVE(&p->p_threads, td, td_plist); 581 p->p_numthreads--; 582 /* could clear a few other things here */ 583 /* Must NOT clear links to proc! */ 584 } 585 586 /* 587 * Enforce single-threading. 588 * 589 * Returns 1 if the caller must abort (another thread is waiting to 590 * exit the process or similar). Process is locked! 591 * Returns 0 when you are successfully the only thread running. 592 * A process has successfully single threaded in the suspend mode when 593 * There are no threads in user mode. Threads in the kernel must be 594 * allowed to continue until they get to the user boundary. They may even 595 * copy out their return values and data before suspending. They may however be 596 * accelerated in reaching the user boundary as we will wake up 597 * any sleeping threads that are interruptable. (PCATCH). 598 */ 599 int 600 thread_single(int mode) 601 { 602 struct thread *td; 603 struct thread *td2; 604 struct proc *p; 605 int remaining; 606 607 td = curthread; 608 p = td->td_proc; 609 mtx_assert(&Giant, MA_NOTOWNED); 610 PROC_LOCK_ASSERT(p, MA_OWNED); 611 KASSERT((td != NULL), ("curthread is NULL")); 612 613 if ((p->p_flag & P_HADTHREADS) == 0) 614 return (0); 615 616 /* Is someone already single threading? */ 617 if (p->p_singlethread != NULL && p->p_singlethread != td) 618 return (1); 619 620 if (mode == SINGLE_EXIT) { 621 p->p_flag |= P_SINGLE_EXIT; 622 p->p_flag &= ~P_SINGLE_BOUNDARY; 623 } else { 624 p->p_flag &= ~P_SINGLE_EXIT; 625 if (mode == SINGLE_BOUNDARY) 626 p->p_flag |= P_SINGLE_BOUNDARY; 627 else 628 p->p_flag &= ~P_SINGLE_BOUNDARY; 629 } 630 p->p_flag |= P_STOPPED_SINGLE; 631 mtx_lock_spin(&sched_lock); 632 p->p_singlethread = td; 633 if (mode == SINGLE_EXIT) 634 remaining = p->p_numthreads; 635 else if (mode == SINGLE_BOUNDARY) 636 remaining = p->p_numthreads - p->p_boundary_count; 637 else 638 remaining = p->p_numthreads - p->p_suspcount; 639 while (remaining != 1) { 640 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 641 goto stopme; 642 FOREACH_THREAD_IN_PROC(p, td2) { 643 if (td2 == td) 644 continue; 645 td2->td_flags |= TDF_ASTPENDING; 646 if (TD_IS_INHIBITED(td2)) { 647 switch (mode) { 648 case SINGLE_EXIT: 649 if (td->td_flags & TDF_DBSUSPEND) 650 td->td_flags &= ~TDF_DBSUSPEND; 651 if (TD_IS_SUSPENDED(td2)) 652 thread_unsuspend_one(td2); 653 if (TD_ON_SLEEPQ(td2) && 654 (td2->td_flags & TDF_SINTR)) 655 sleepq_abort(td2, EINTR); 656 break; 657 case SINGLE_BOUNDARY: 658 if (TD_IS_SUSPENDED(td2) && 659 !(td2->td_flags & TDF_BOUNDARY)) 660 thread_unsuspend_one(td2); 661 if (TD_ON_SLEEPQ(td2) && 662 (td2->td_flags & TDF_SINTR)) 663 sleepq_abort(td2, ERESTART); 664 break; 665 default: 666 if (TD_IS_SUSPENDED(td2)) 667 continue; 668 /* 669 * maybe other inhibited states too? 670 */ 671 if ((td2->td_flags & TDF_SINTR) && 672 (td2->td_inhibitors & 673 (TDI_SLEEPING | TDI_SWAPPED))) 674 thread_suspend_one(td2); 675 break; 676 } 677 } 678 #ifdef SMP 679 else if (TD_IS_RUNNING(td2) && td != td2) { 680 forward_signal(td2); 681 } 682 #endif 683 } 684 if (mode == SINGLE_EXIT) 685 remaining = p->p_numthreads; 686 else if (mode == SINGLE_BOUNDARY) 687 remaining = p->p_numthreads - p->p_boundary_count; 688 else 689 remaining = p->p_numthreads - p->p_suspcount; 690 691 /* 692 * Maybe we suspended some threads.. was it enough? 693 */ 694 if (remaining == 1) 695 break; 696 697 stopme: 698 /* 699 * Wake us up when everyone else has suspended. 700 * In the mean time we suspend as well. 701 */ 702 thread_stopped(p); 703 thread_suspend_one(td); 704 PROC_UNLOCK(p); 705 mi_switch(SW_VOL, NULL); 706 mtx_unlock_spin(&sched_lock); 707 PROC_LOCK(p); 708 mtx_lock_spin(&sched_lock); 709 if (mode == SINGLE_EXIT) 710 remaining = p->p_numthreads; 711 else if (mode == SINGLE_BOUNDARY) 712 remaining = p->p_numthreads - p->p_boundary_count; 713 else 714 remaining = p->p_numthreads - p->p_suspcount; 715 } 716 if (mode == SINGLE_EXIT) { 717 /* 718 * We have gotten rid of all the other threads and we 719 * are about to either exit or exec. In either case, 720 * we try our utmost to revert to being a non-threaded 721 * process. 722 */ 723 p->p_singlethread = NULL; 724 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 725 thread_unthread(td); 726 } 727 mtx_unlock_spin(&sched_lock); 728 return (0); 729 } 730 731 /* 732 * Called in from locations that can safely check to see 733 * whether we have to suspend or at least throttle for a 734 * single-thread event (e.g. fork). 735 * 736 * Such locations include userret(). 737 * If the "return_instead" argument is non zero, the thread must be able to 738 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 739 * 740 * The 'return_instead' argument tells the function if it may do a 741 * thread_exit() or suspend, or whether the caller must abort and back 742 * out instead. 743 * 744 * If the thread that set the single_threading request has set the 745 * P_SINGLE_EXIT bit in the process flags then this call will never return 746 * if 'return_instead' is false, but will exit. 747 * 748 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 749 *---------------+--------------------+--------------------- 750 * 0 | returns 0 | returns 0 or 1 751 * | when ST ends | immediatly 752 *---------------+--------------------+--------------------- 753 * 1 | thread exits | returns 1 754 * | | immediatly 755 * 0 = thread_exit() or suspension ok, 756 * other = return error instead of stopping the thread. 757 * 758 * While a full suspension is under effect, even a single threading 759 * thread would be suspended if it made this call (but it shouldn't). 760 * This call should only be made from places where 761 * thread_exit() would be safe as that may be the outcome unless 762 * return_instead is set. 763 */ 764 int 765 thread_suspend_check(int return_instead) 766 { 767 struct thread *td; 768 struct proc *p; 769 770 td = curthread; 771 p = td->td_proc; 772 mtx_assert(&Giant, MA_NOTOWNED); 773 PROC_LOCK_ASSERT(p, MA_OWNED); 774 while (P_SHOULDSTOP(p) || 775 ((p->p_flag & P_TRACED) && (td->td_flags & TDF_DBSUSPEND))) { 776 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 777 KASSERT(p->p_singlethread != NULL, 778 ("singlethread not set")); 779 /* 780 * The only suspension in action is a 781 * single-threading. Single threader need not stop. 782 * XXX Should be safe to access unlocked 783 * as it can only be set to be true by us. 784 */ 785 if (p->p_singlethread == td) 786 return (0); /* Exempt from stopping. */ 787 } 788 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 789 return (EINTR); 790 791 /* Should we goto user boundary if we didn't come from there? */ 792 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 793 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 794 return (ERESTART); 795 796 /* If thread will exit, flush its pending signals */ 797 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 798 sigqueue_flush(&td->td_sigqueue); 799 800 mtx_lock_spin(&sched_lock); 801 thread_stopped(p); 802 /* 803 * If the process is waiting for us to exit, 804 * this thread should just suicide. 805 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 806 */ 807 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 808 thread_exit(); 809 810 /* 811 * When a thread suspends, it just 812 * gets taken off all queues. 813 */ 814 thread_suspend_one(td); 815 if (return_instead == 0) { 816 p->p_boundary_count++; 817 td->td_flags |= TDF_BOUNDARY; 818 } 819 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 820 if (p->p_numthreads == p->p_suspcount) 821 thread_unsuspend_one(p->p_singlethread); 822 } 823 PROC_UNLOCK(p); 824 mi_switch(SW_INVOL, NULL); 825 if (return_instead == 0) { 826 p->p_boundary_count--; 827 td->td_flags &= ~TDF_BOUNDARY; 828 } 829 mtx_unlock_spin(&sched_lock); 830 PROC_LOCK(p); 831 } 832 return (0); 833 } 834 835 void 836 thread_suspend_one(struct thread *td) 837 { 838 struct proc *p = td->td_proc; 839 840 mtx_assert(&sched_lock, MA_OWNED); 841 PROC_LOCK_ASSERT(p, MA_OWNED); 842 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 843 p->p_suspcount++; 844 TD_SET_SUSPENDED(td); 845 } 846 847 void 848 thread_unsuspend_one(struct thread *td) 849 { 850 struct proc *p = td->td_proc; 851 852 mtx_assert(&sched_lock, MA_OWNED); 853 PROC_LOCK_ASSERT(p, MA_OWNED); 854 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 855 TD_CLR_SUSPENDED(td); 856 p->p_suspcount--; 857 setrunnable(td); 858 } 859 860 /* 861 * Allow all threads blocked by single threading to continue running. 862 */ 863 void 864 thread_unsuspend(struct proc *p) 865 { 866 struct thread *td; 867 868 mtx_assert(&sched_lock, MA_OWNED); 869 PROC_LOCK_ASSERT(p, MA_OWNED); 870 if (!P_SHOULDSTOP(p)) { 871 FOREACH_THREAD_IN_PROC(p, td) { 872 if (TD_IS_SUSPENDED(td)) { 873 thread_unsuspend_one(td); 874 } 875 } 876 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 877 (p->p_numthreads == p->p_suspcount)) { 878 /* 879 * Stopping everything also did the job for the single 880 * threading request. Now we've downgraded to single-threaded, 881 * let it continue. 882 */ 883 thread_unsuspend_one(p->p_singlethread); 884 } 885 } 886 887 /* 888 * End the single threading mode.. 889 */ 890 void 891 thread_single_end(void) 892 { 893 struct thread *td; 894 struct proc *p; 895 896 td = curthread; 897 p = td->td_proc; 898 PROC_LOCK_ASSERT(p, MA_OWNED); 899 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 900 mtx_lock_spin(&sched_lock); 901 p->p_singlethread = NULL; 902 /* 903 * If there are other threads they mey now run, 904 * unless of course there is a blanket 'stop order' 905 * on the process. The single threader must be allowed 906 * to continue however as this is a bad place to stop. 907 */ 908 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 909 FOREACH_THREAD_IN_PROC(p, td) { 910 if (TD_IS_SUSPENDED(td)) { 911 thread_unsuspend_one(td); 912 } 913 } 914 } 915 mtx_unlock_spin(&sched_lock); 916 } 917 918 struct thread * 919 thread_find(struct proc *p, lwpid_t tid) 920 { 921 struct thread *td; 922 923 PROC_LOCK_ASSERT(p, MA_OWNED); 924 mtx_lock_spin(&sched_lock); 925 FOREACH_THREAD_IN_PROC(p, td) { 926 if (td->td_tid == tid) 927 break; 928 } 929 mtx_unlock_spin(&sched_lock); 930 return (td); 931 } 932