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 zombie_lock; 74 MTX_SYSINIT(zombie_lock, &zombie_lock, "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. 125 */ 126 td->td_critnest = 1; 127 128 #ifdef AUDIT 129 audit_thread_alloc(td); 130 #endif 131 umtx_thread_alloc(td); 132 return (0); 133 } 134 135 /* 136 * Reclaim a thread after use. 137 */ 138 static void 139 thread_dtor(void *mem, int size, void *arg) 140 { 141 struct thread *td; 142 143 td = (struct thread *)mem; 144 145 #ifdef INVARIANTS 146 /* Verify that this thread is in a safe state to free. */ 147 switch (td->td_state) { 148 case TDS_INHIBITED: 149 case TDS_RUNNING: 150 case TDS_CAN_RUN: 151 case TDS_RUNQ: 152 /* 153 * We must never unlink a thread that is in one of 154 * these states, because it is currently active. 155 */ 156 panic("bad state for thread unlinking"); 157 /* NOTREACHED */ 158 case TDS_INACTIVE: 159 break; 160 default: 161 panic("bad thread state"); 162 /* NOTREACHED */ 163 } 164 #endif 165 #ifdef AUDIT 166 audit_thread_free(td); 167 #endif 168 free_unr(tid_unrhdr, td->td_tid); 169 sched_newthread(td); 170 } 171 172 /* 173 * Initialize type-stable parts of a thread (when newly created). 174 */ 175 static int 176 thread_init(void *mem, int size, int flags) 177 { 178 struct thread *td; 179 180 td = (struct thread *)mem; 181 182 vm_thread_new(td, 0); 183 cpu_thread_setup(td); 184 td->td_sleepqueue = sleepq_alloc(); 185 td->td_turnstile = turnstile_alloc(); 186 td->td_sched = (struct td_sched *)&td[1]; 187 sched_newthread(td); 188 umtx_thread_init(td); 189 return (0); 190 } 191 192 /* 193 * Tear down type-stable parts of a thread (just before being discarded). 194 */ 195 static void 196 thread_fini(void *mem, int size) 197 { 198 struct thread *td; 199 200 td = (struct thread *)mem; 201 turnstile_free(td->td_turnstile); 202 sleepq_free(td->td_sleepqueue); 203 umtx_thread_fini(td); 204 vm_thread_dispose(td); 205 } 206 207 /* 208 * For a newly created process, 209 * link up all the structures and its initial threads etc. 210 * called from: 211 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 212 * proc_dtor() (should go away) 213 * proc_init() 214 */ 215 void 216 proc_linkup(struct proc *p, struct thread *td) 217 { 218 219 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 220 TAILQ_INIT(&p->p_upcalls); /* upcall list */ 221 sigqueue_init(&p->p_sigqueue, p); 222 p->p_ksi = ksiginfo_alloc(1); 223 if (p->p_ksi != NULL) { 224 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 225 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 226 } 227 LIST_INIT(&p->p_mqnotifier); 228 p->p_numthreads = 0; 229 thread_link(td, p); 230 } 231 232 /* 233 * Initialize global thread allocation resources. 234 */ 235 void 236 threadinit(void) 237 { 238 239 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 240 tid_unrhdr = new_unrhdr(PID_MAX + 1, INT_MAX, &tid_lock); 241 242 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 243 thread_ctor, thread_dtor, thread_init, thread_fini, 244 16 - 1, 0); 245 #ifdef KSE 246 kseinit(); /* set up kse specific stuff e.g. upcall zone*/ 247 #endif 248 } 249 250 /* 251 * Stash an embarasingly extra thread into the zombie thread queue. 252 * Use the slpq as that must be unused by now. 253 */ 254 void 255 thread_stash(struct thread *td) 256 { 257 mtx_lock_spin(&zombie_lock); 258 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 259 mtx_unlock_spin(&zombie_lock); 260 } 261 262 /* 263 * Reap zombie kse resource. 264 */ 265 void 266 thread_reap(void) 267 { 268 struct thread *td_first, *td_next; 269 270 /* 271 * Don't even bother to lock if none at this instant, 272 * we really don't care about the next instant.. 273 */ 274 if (!TAILQ_EMPTY(&zombie_threads)) { 275 mtx_lock_spin(&zombie_lock); 276 td_first = TAILQ_FIRST(&zombie_threads); 277 if (td_first) 278 TAILQ_INIT(&zombie_threads); 279 mtx_unlock_spin(&zombie_lock); 280 while (td_first) { 281 td_next = TAILQ_NEXT(td_first, td_slpq); 282 if (td_first->td_ucred) 283 crfree(td_first->td_ucred); 284 thread_free(td_first); 285 td_first = td_next; 286 } 287 } 288 } 289 290 /* 291 * Allocate a thread. 292 */ 293 struct thread * 294 thread_alloc(void) 295 { 296 297 thread_reap(); /* check if any zombies to get */ 298 return (uma_zalloc(thread_zone, M_WAITOK)); 299 } 300 301 302 /* 303 * Deallocate a thread. 304 */ 305 void 306 thread_free(struct thread *td) 307 { 308 309 cpu_thread_clean(td); 310 uma_zfree(thread_zone, td); 311 } 312 313 /* 314 * Discard the current thread and exit from its context. 315 * Always called with scheduler locked. 316 * 317 * Because we can't free a thread while we're operating under its context, 318 * push the current thread into our CPU's deadthread holder. This means 319 * we needn't worry about someone else grabbing our context before we 320 * do a cpu_throw(). This may not be needed now as we are under schedlock. 321 * Maybe we can just do a thread_stash() as thr_exit1 does. 322 */ 323 /* XXX 324 * libthr expects its thread exit to return for the last 325 * thread, meaning that the program is back to non-threaded 326 * mode I guess. Because we do this (cpu_throw) unconditionally 327 * here, they have their own version of it. (thr_exit1()) 328 * that doesn't do it all if this was the last thread. 329 * It is also called from thread_suspend_check(). 330 * Of course in the end, they end up coming here through exit1 331 * anyhow.. After fixing 'thr' to play by the rules we should be able 332 * to merge these two functions together. 333 * 334 * called from: 335 * exit1() 336 * kse_exit() 337 * thr_exit() 338 * ifdef KSE 339 * thread_user_enter() 340 * thread_userret() 341 * endif 342 * thread_suspend_check() 343 */ 344 void 345 thread_exit(void) 346 { 347 uint64_t new_switchtime; 348 struct thread *td; 349 struct thread *td2; 350 struct proc *p; 351 352 td = curthread; 353 p = td->td_proc; 354 355 PROC_SLOCK_ASSERT(p, MA_OWNED); 356 mtx_assert(&Giant, MA_NOTOWNED); 357 358 PROC_LOCK_ASSERT(p, MA_OWNED); 359 KASSERT(p != NULL, ("thread exiting without a process")); 360 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 361 (long)p->p_pid, p->p_comm); 362 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 363 364 #ifdef AUDIT 365 AUDIT_SYSCALL_EXIT(0, td); 366 #endif 367 368 #ifdef KSE 369 if (td->td_standin != NULL) { 370 /* 371 * Note that we don't need to free the cred here as it 372 * is done in thread_reap(). 373 */ 374 thread_stash(td->td_standin); 375 td->td_standin = NULL; 376 } 377 #endif 378 379 umtx_thread_exit(td); 380 381 /* 382 * drop FPU & debug register state storage, or any other 383 * architecture specific resources that 384 * would not be on a new untouched process. 385 */ 386 cpu_thread_exit(td); /* XXXSMP */ 387 388 /* Do the same timestamp bookkeeping that mi_switch() would do. */ 389 new_switchtime = cpu_ticks(); 390 p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime)); 391 PCPU_SET(switchtime, new_switchtime); 392 PCPU_SET(switchticks, ticks); 393 PCPU_INC(cnt.v_swtch); 394 /* Add the child usage to our own when the final thread exits. */ 395 if (p->p_numthreads == 1) 396 ruadd(p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux); 397 /* 398 * The last thread is left attached to the process 399 * So that the whole bundle gets recycled. Skip 400 * all this stuff if we never had threads. 401 * EXIT clears all sign of other threads when 402 * it goes to single threading, so the last thread always 403 * takes the short path. 404 */ 405 if (p->p_flag & P_HADTHREADS) { 406 if (p->p_numthreads > 1) { 407 thread_lock(td); 408 #ifdef KSE 409 kse_unlink(td); 410 #else 411 thread_unlink(td); 412 #endif 413 thread_unlock(td); 414 /* Impart our resource usage on another thread */ 415 td2 = FIRST_THREAD_IN_PROC(p); 416 rucollect(&td2->td_ru, &td->td_ru); 417 sched_exit_thread(td2, td); 418 419 /* 420 * The test below is NOT true if we are the 421 * sole exiting thread. P_STOPPED_SNGL is unset 422 * in exit1() after it is the only survivor. 423 */ 424 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 425 if (p->p_numthreads == p->p_suspcount) { 426 thread_lock(p->p_singlethread); 427 thread_unsuspend_one(p->p_singlethread); 428 thread_unlock(p->p_singlethread); 429 } 430 } 431 432 #ifdef KSE 433 /* 434 * Because each upcall structure has an owner thread, 435 * owner thread exits only when process is in exiting 436 * state, so upcall to userland is no longer needed, 437 * deleting upcall structure is safe here. 438 * So when all threads in a group is exited, all upcalls 439 * in the group should be automatically freed. 440 * XXXKSE This is a KSE thing and should be exported 441 * there somehow. 442 */ 443 upcall_remove(td); 444 #endif 445 PCPU_SET(deadthread, td); 446 } else { 447 /* 448 * The last thread is exiting.. but not through exit() 449 * what should we do? 450 * Theoretically this can't happen 451 * exit1() - clears threading flags before coming here 452 * kse_exit() - treats last thread specially 453 * thr_exit() - treats last thread specially 454 * ifdef KSE 455 * thread_user_enter() - only if more exist 456 * thread_userret() - only if more exist 457 * endif 458 * thread_suspend_check() - only if more exist 459 */ 460 panic ("thread_exit: Last thread exiting on its own"); 461 } 462 } 463 PROC_UNLOCK(p); 464 thread_lock(td); 465 /* Aggregate our tick statistics into our parents rux. */ 466 ruxagg(&p->p_rux, td); 467 PROC_SUNLOCK(p); 468 td->td_state = TDS_INACTIVE; 469 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 470 sched_throw(td); 471 panic("I'm a teapot!"); 472 /* NOTREACHED */ 473 } 474 475 /* 476 * Do any thread specific cleanups that may be needed in wait() 477 * called with Giant, proc and schedlock not held. 478 */ 479 void 480 thread_wait(struct proc *p) 481 { 482 struct thread *td; 483 484 mtx_assert(&Giant, MA_NOTOWNED); 485 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 486 FOREACH_THREAD_IN_PROC(p, td) { 487 #ifdef KSE 488 if (td->td_standin != NULL) { 489 if (td->td_standin->td_ucred != NULL) { 490 crfree(td->td_standin->td_ucred); 491 td->td_standin->td_ucred = NULL; 492 } 493 thread_free(td->td_standin); 494 td->td_standin = NULL; 495 } 496 #endif 497 cpu_thread_clean(td); 498 crfree(td->td_ucred); 499 } 500 thread_reap(); /* check for zombie threads etc. */ 501 } 502 503 /* 504 * Link a thread to a process. 505 * set up anything that needs to be initialized for it to 506 * be used by the process. 507 * 508 * Note that we do not link to the proc's ucred here. 509 * The thread is linked as if running but no KSE assigned. 510 * Called from: 511 * proc_linkup() 512 * thread_schedule_upcall() 513 * thr_create() 514 */ 515 void 516 thread_link(struct thread *td, struct proc *p) 517 { 518 519 /* 520 * XXX This can't be enabled because it's called for proc0 before 521 * it's spinlock has been created. 522 * PROC_SLOCK_ASSERT(p, MA_OWNED); 523 */ 524 td->td_state = TDS_INACTIVE; 525 td->td_proc = p; 526 td->td_flags = 0; 527 528 LIST_INIT(&td->td_contested); 529 sigqueue_init(&td->td_sigqueue, p); 530 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 531 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 532 p->p_numthreads++; 533 } 534 535 /* 536 * Convert a process with one thread to an unthreaded process. 537 * Called from: 538 * thread_single(exit) (called from execve and exit) 539 * kse_exit() XXX may need cleaning up wrt KSE stuff 540 */ 541 void 542 thread_unthread(struct thread *td) 543 { 544 struct proc *p = td->td_proc; 545 546 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 547 #ifdef KSE 548 upcall_remove(td); 549 p->p_flag &= ~(P_SA|P_HADTHREADS); 550 td->td_mailbox = NULL; 551 td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND); 552 if (td->td_standin != NULL) { 553 thread_stash(td->td_standin); 554 td->td_standin = NULL; 555 } 556 sched_set_concurrency(p, 1); 557 #else 558 p->p_flag &= ~P_HADTHREADS; 559 #endif 560 } 561 562 /* 563 * Called from: 564 * thread_exit() 565 */ 566 void 567 thread_unlink(struct thread *td) 568 { 569 struct proc *p = td->td_proc; 570 571 PROC_SLOCK_ASSERT(p, MA_OWNED); 572 TAILQ_REMOVE(&p->p_threads, td, td_plist); 573 p->p_numthreads--; 574 /* could clear a few other things here */ 575 /* Must NOT clear links to proc! */ 576 } 577 578 /* 579 * Enforce single-threading. 580 * 581 * Returns 1 if the caller must abort (another thread is waiting to 582 * exit the process or similar). Process is locked! 583 * Returns 0 when you are successfully the only thread running. 584 * A process has successfully single threaded in the suspend mode when 585 * There are no threads in user mode. Threads in the kernel must be 586 * allowed to continue until they get to the user boundary. They may even 587 * copy out their return values and data before suspending. They may however be 588 * accelerated in reaching the user boundary as we will wake up 589 * any sleeping threads that are interruptable. (PCATCH). 590 */ 591 int 592 thread_single(int mode) 593 { 594 struct thread *td; 595 struct thread *td2; 596 struct proc *p; 597 int remaining; 598 599 td = curthread; 600 p = td->td_proc; 601 mtx_assert(&Giant, MA_NOTOWNED); 602 PROC_LOCK_ASSERT(p, MA_OWNED); 603 KASSERT((td != NULL), ("curthread is NULL")); 604 605 if ((p->p_flag & P_HADTHREADS) == 0) 606 return (0); 607 608 /* Is someone already single threading? */ 609 if (p->p_singlethread != NULL && p->p_singlethread != td) 610 return (1); 611 612 if (mode == SINGLE_EXIT) { 613 p->p_flag |= P_SINGLE_EXIT; 614 p->p_flag &= ~P_SINGLE_BOUNDARY; 615 } else { 616 p->p_flag &= ~P_SINGLE_EXIT; 617 if (mode == SINGLE_BOUNDARY) 618 p->p_flag |= P_SINGLE_BOUNDARY; 619 else 620 p->p_flag &= ~P_SINGLE_BOUNDARY; 621 } 622 p->p_flag |= P_STOPPED_SINGLE; 623 PROC_SLOCK(p); 624 p->p_singlethread = td; 625 if (mode == SINGLE_EXIT) 626 remaining = p->p_numthreads; 627 else if (mode == SINGLE_BOUNDARY) 628 remaining = p->p_numthreads - p->p_boundary_count; 629 else 630 remaining = p->p_numthreads - p->p_suspcount; 631 while (remaining != 1) { 632 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 633 goto stopme; 634 FOREACH_THREAD_IN_PROC(p, td2) { 635 if (td2 == td) 636 continue; 637 thread_lock(td2); 638 td2->td_flags |= TDF_ASTPENDING; 639 if (TD_IS_INHIBITED(td2)) { 640 switch (mode) { 641 case SINGLE_EXIT: 642 if (td->td_flags & TDF_DBSUSPEND) 643 td->td_flags &= ~TDF_DBSUSPEND; 644 if (TD_IS_SUSPENDED(td2)) 645 thread_unsuspend_one(td2); 646 if (TD_ON_SLEEPQ(td2) && 647 (td2->td_flags & TDF_SINTR)) 648 sleepq_abort(td2, EINTR); 649 break; 650 case SINGLE_BOUNDARY: 651 if (TD_IS_SUSPENDED(td2) && 652 !(td2->td_flags & TDF_BOUNDARY)) 653 thread_unsuspend_one(td2); 654 if (TD_ON_SLEEPQ(td2) && 655 (td2->td_flags & TDF_SINTR)) 656 sleepq_abort(td2, ERESTART); 657 break; 658 default: 659 if (TD_IS_SUSPENDED(td2)) { 660 thread_unlock(td2); 661 continue; 662 } 663 /* 664 * maybe other inhibited states too? 665 */ 666 if ((td2->td_flags & TDF_SINTR) && 667 (td2->td_inhibitors & 668 (TDI_SLEEPING | TDI_SWAPPED))) 669 thread_suspend_one(td2); 670 break; 671 } 672 } 673 #ifdef SMP 674 else if (TD_IS_RUNNING(td2) && td != td2) { 675 forward_signal(td2); 676 } 677 #endif 678 thread_unlock(td2); 679 } 680 if (mode == SINGLE_EXIT) 681 remaining = p->p_numthreads; 682 else if (mode == SINGLE_BOUNDARY) 683 remaining = p->p_numthreads - p->p_boundary_count; 684 else 685 remaining = p->p_numthreads - p->p_suspcount; 686 687 /* 688 * Maybe we suspended some threads.. was it enough? 689 */ 690 if (remaining == 1) 691 break; 692 693 stopme: 694 /* 695 * Wake us up when everyone else has suspended. 696 * In the mean time we suspend as well. 697 */ 698 thread_suspend_switch(td); 699 if (mode == SINGLE_EXIT) 700 remaining = p->p_numthreads; 701 else if (mode == SINGLE_BOUNDARY) 702 remaining = p->p_numthreads - p->p_boundary_count; 703 else 704 remaining = p->p_numthreads - p->p_suspcount; 705 } 706 if (mode == SINGLE_EXIT) { 707 /* 708 * We have gotten rid of all the other threads and we 709 * are about to either exit or exec. In either case, 710 * we try our utmost to revert to being a non-threaded 711 * process. 712 */ 713 p->p_singlethread = NULL; 714 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 715 thread_unthread(td); 716 } 717 PROC_SUNLOCK(p); 718 return (0); 719 } 720 721 /* 722 * Called in from locations that can safely check to see 723 * whether we have to suspend or at least throttle for a 724 * single-thread event (e.g. fork). 725 * 726 * Such locations include userret(). 727 * If the "return_instead" argument is non zero, the thread must be able to 728 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 729 * 730 * The 'return_instead' argument tells the function if it may do a 731 * thread_exit() or suspend, or whether the caller must abort and back 732 * out instead. 733 * 734 * If the thread that set the single_threading request has set the 735 * P_SINGLE_EXIT bit in the process flags then this call will never return 736 * if 'return_instead' is false, but will exit. 737 * 738 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 739 *---------------+--------------------+--------------------- 740 * 0 | returns 0 | returns 0 or 1 741 * | when ST ends | immediatly 742 *---------------+--------------------+--------------------- 743 * 1 | thread exits | returns 1 744 * | | immediatly 745 * 0 = thread_exit() or suspension ok, 746 * other = return error instead of stopping the thread. 747 * 748 * While a full suspension is under effect, even a single threading 749 * thread would be suspended if it made this call (but it shouldn't). 750 * This call should only be made from places where 751 * thread_exit() would be safe as that may be the outcome unless 752 * return_instead is set. 753 */ 754 int 755 thread_suspend_check(int return_instead) 756 { 757 struct thread *td; 758 struct proc *p; 759 760 td = curthread; 761 p = td->td_proc; 762 mtx_assert(&Giant, MA_NOTOWNED); 763 PROC_LOCK_ASSERT(p, MA_OWNED); 764 while (P_SHOULDSTOP(p) || 765 ((p->p_flag & P_TRACED) && (td->td_flags & TDF_DBSUSPEND))) { 766 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 767 KASSERT(p->p_singlethread != NULL, 768 ("singlethread not set")); 769 /* 770 * The only suspension in action is a 771 * single-threading. Single threader need not stop. 772 * XXX Should be safe to access unlocked 773 * as it can only be set to be true by us. 774 */ 775 if (p->p_singlethread == td) 776 return (0); /* Exempt from stopping. */ 777 } 778 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 779 return (EINTR); 780 781 /* Should we goto user boundary if we didn't come from there? */ 782 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 783 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 784 return (ERESTART); 785 786 /* If thread will exit, flush its pending signals */ 787 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 788 sigqueue_flush(&td->td_sigqueue); 789 790 PROC_SLOCK(p); 791 thread_stopped(p); 792 /* 793 * If the process is waiting for us to exit, 794 * this thread should just suicide. 795 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 796 */ 797 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 798 thread_exit(); 799 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 800 if (p->p_numthreads == p->p_suspcount + 1) { 801 thread_lock(p->p_singlethread); 802 thread_unsuspend_one(p->p_singlethread); 803 thread_unlock(p->p_singlethread); 804 } 805 } 806 PROC_UNLOCK(p); 807 thread_lock(td); 808 /* 809 * When a thread suspends, it just 810 * gets taken off all queues. 811 */ 812 thread_suspend_one(td); 813 if (return_instead == 0) { 814 p->p_boundary_count++; 815 td->td_flags |= TDF_BOUNDARY; 816 } 817 PROC_SUNLOCK(p); 818 mi_switch(SW_INVOL, NULL); 819 if (return_instead == 0) 820 td->td_flags &= ~TDF_BOUNDARY; 821 thread_unlock(td); 822 PROC_LOCK(p); 823 if (return_instead == 0) 824 p->p_boundary_count--; 825 } 826 return (0); 827 } 828 829 void 830 thread_suspend_switch(struct thread *td) 831 { 832 struct proc *p; 833 834 p = td->td_proc; 835 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 836 PROC_LOCK_ASSERT(p, MA_OWNED); 837 PROC_SLOCK_ASSERT(p, MA_OWNED); 838 /* 839 * We implement thread_suspend_one in stages here to avoid 840 * dropping the proc lock while the thread lock is owned. 841 */ 842 thread_stopped(p); 843 p->p_suspcount++; 844 PROC_UNLOCK(p); 845 thread_lock(td); 846 TD_SET_SUSPENDED(td); 847 PROC_SUNLOCK(p); 848 DROP_GIANT(); 849 mi_switch(SW_VOL, NULL); 850 thread_unlock(td); 851 PICKUP_GIANT(); 852 PROC_LOCK(p); 853 PROC_SLOCK(p); 854 } 855 856 void 857 thread_suspend_one(struct thread *td) 858 { 859 struct proc *p = td->td_proc; 860 861 PROC_SLOCK_ASSERT(p, MA_OWNED); 862 THREAD_LOCK_ASSERT(td, MA_OWNED); 863 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 864 p->p_suspcount++; 865 TD_SET_SUSPENDED(td); 866 } 867 868 void 869 thread_unsuspend_one(struct thread *td) 870 { 871 struct proc *p = td->td_proc; 872 873 PROC_SLOCK_ASSERT(p, MA_OWNED); 874 THREAD_LOCK_ASSERT(td, MA_OWNED); 875 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 876 TD_CLR_SUSPENDED(td); 877 p->p_suspcount--; 878 setrunnable(td); 879 } 880 881 /* 882 * Allow all threads blocked by single threading to continue running. 883 */ 884 void 885 thread_unsuspend(struct proc *p) 886 { 887 struct thread *td; 888 889 PROC_LOCK_ASSERT(p, MA_OWNED); 890 PROC_SLOCK_ASSERT(p, MA_OWNED); 891 if (!P_SHOULDSTOP(p)) { 892 FOREACH_THREAD_IN_PROC(p, td) { 893 thread_lock(td); 894 if (TD_IS_SUSPENDED(td)) { 895 thread_unsuspend_one(td); 896 } 897 thread_unlock(td); 898 } 899 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 900 (p->p_numthreads == p->p_suspcount)) { 901 /* 902 * Stopping everything also did the job for the single 903 * threading request. Now we've downgraded to single-threaded, 904 * let it continue. 905 */ 906 thread_lock(p->p_singlethread); 907 thread_unsuspend_one(p->p_singlethread); 908 thread_unlock(p->p_singlethread); 909 } 910 } 911 912 /* 913 * End the single threading mode.. 914 */ 915 void 916 thread_single_end(void) 917 { 918 struct thread *td; 919 struct proc *p; 920 921 td = curthread; 922 p = td->td_proc; 923 PROC_LOCK_ASSERT(p, MA_OWNED); 924 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 925 PROC_SLOCK(p); 926 p->p_singlethread = NULL; 927 /* 928 * If there are other threads they mey now run, 929 * unless of course there is a blanket 'stop order' 930 * on the process. The single threader must be allowed 931 * to continue however as this is a bad place to stop. 932 */ 933 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 934 FOREACH_THREAD_IN_PROC(p, td) { 935 thread_lock(td); 936 if (TD_IS_SUSPENDED(td)) { 937 thread_unsuspend_one(td); 938 } 939 thread_unlock(td); 940 } 941 } 942 PROC_SUNLOCK(p); 943 } 944 945 struct thread * 946 thread_find(struct proc *p, lwpid_t tid) 947 { 948 struct thread *td; 949 950 PROC_LOCK_ASSERT(p, MA_OWNED); 951 PROC_SLOCK(p); 952 FOREACH_THREAD_IN_PROC(p, td) { 953 if (td->td_tid == tid) 954 break; 955 } 956 PROC_SUNLOCK(p); 957 return (td); 958 } 959