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 static void thread_zombie(struct thread *); 77 78 #ifdef KSE 79 static int 80 sysctl_kse_virtual_cpu(SYSCTL_HANDLER_ARGS) 81 { 82 int error, new_val; 83 int def_val; 84 85 def_val = mp_ncpus; 86 if (virtual_cpu == 0) 87 new_val = def_val; 88 else 89 new_val = virtual_cpu; 90 error = sysctl_handle_int(oidp, &new_val, 0, req); 91 if (error != 0 || req->newptr == NULL) 92 return (error); 93 if (new_val < 0) 94 return (EINVAL); 95 virtual_cpu = new_val; 96 return (0); 97 } 98 99 /* DEBUG ONLY */ 100 SYSCTL_PROC(_kern_threads, OID_AUTO, virtual_cpu, CTLTYPE_INT|CTLFLAG_RW, 101 0, sizeof(virtual_cpu), sysctl_kse_virtual_cpu, "I", 102 "debug virtual cpus"); 103 #endif 104 105 struct mtx tid_lock; 106 static struct unrhdr *tid_unrhdr; 107 108 /* 109 * Prepare a thread for use. 110 */ 111 static int 112 thread_ctor(void *mem, int size, void *arg, int flags) 113 { 114 struct thread *td; 115 116 td = (struct thread *)mem; 117 td->td_state = TDS_INACTIVE; 118 td->td_oncpu = NOCPU; 119 120 td->td_tid = alloc_unr(tid_unrhdr); 121 td->td_syscalls = 0; 122 123 /* 124 * Note that td_critnest begins life as 1 because the thread is not 125 * running and is thereby implicitly waiting to be on the receiving 126 * end of a context switch. 127 */ 128 td->td_critnest = 1; 129 130 #ifdef AUDIT 131 audit_thread_alloc(td); 132 #endif 133 umtx_thread_alloc(td); 134 return (0); 135 } 136 137 /* 138 * Reclaim a thread after use. 139 */ 140 static void 141 thread_dtor(void *mem, int size, void *arg) 142 { 143 struct thread *td; 144 145 td = (struct thread *)mem; 146 147 #ifdef INVARIANTS 148 /* Verify that this thread is in a safe state to free. */ 149 switch (td->td_state) { 150 case TDS_INHIBITED: 151 case TDS_RUNNING: 152 case TDS_CAN_RUN: 153 case TDS_RUNQ: 154 /* 155 * We must never unlink a thread that is in one of 156 * these states, because it is currently active. 157 */ 158 panic("bad state for thread unlinking"); 159 /* NOTREACHED */ 160 case TDS_INACTIVE: 161 break; 162 default: 163 panic("bad thread state"); 164 /* NOTREACHED */ 165 } 166 #endif 167 #ifdef AUDIT 168 audit_thread_free(td); 169 #endif 170 free_unr(tid_unrhdr, td->td_tid); 171 sched_newthread(td); 172 } 173 174 /* 175 * Initialize type-stable parts of a thread (when newly created). 176 */ 177 static int 178 thread_init(void *mem, int size, int flags) 179 { 180 struct thread *td; 181 182 td = (struct thread *)mem; 183 184 vm_thread_new(td, 0); 185 cpu_thread_setup(td); 186 td->td_sleepqueue = sleepq_alloc(); 187 td->td_turnstile = turnstile_alloc(); 188 td->td_sched = (struct td_sched *)&td[1]; 189 sched_newthread(td); 190 umtx_thread_init(td); 191 return (0); 192 } 193 194 /* 195 * Tear down type-stable parts of a thread (just before being discarded). 196 */ 197 static void 198 thread_fini(void *mem, int size) 199 { 200 struct thread *td; 201 202 td = (struct thread *)mem; 203 turnstile_free(td->td_turnstile); 204 sleepq_free(td->td_sleepqueue); 205 umtx_thread_fini(td); 206 vm_thread_dispose(td); 207 } 208 209 /* 210 * For a newly created process, 211 * link up all the structures and its initial threads etc. 212 * called from: 213 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 214 * proc_dtor() (should go away) 215 * proc_init() 216 */ 217 void 218 proc_linkup(struct proc *p, struct thread *td) 219 { 220 221 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 222 #ifdef KSE 223 TAILQ_INIT(&p->p_upcalls); /* upcall list */ 224 #endif 225 sigqueue_init(&p->p_sigqueue, p); 226 p->p_ksi = ksiginfo_alloc(1); 227 if (p->p_ksi != NULL) { 228 /* XXX p_ksi may be null if ksiginfo zone is not ready */ 229 p->p_ksi->ksi_flags = KSI_EXT | KSI_INS; 230 } 231 LIST_INIT(&p->p_mqnotifier); 232 p->p_numthreads = 0; 233 thread_link(td, p); 234 } 235 236 /* 237 * Initialize global thread allocation resources. 238 */ 239 void 240 threadinit(void) 241 { 242 243 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 244 tid_unrhdr = new_unrhdr(PID_MAX + 1, INT_MAX, &tid_lock); 245 246 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 247 thread_ctor, thread_dtor, thread_init, thread_fini, 248 16 - 1, 0); 249 #ifdef KSE 250 kseinit(); /* set up kse specific stuff e.g. upcall zone*/ 251 #endif 252 } 253 254 /* 255 * Place an unused thread on the zombie list. 256 * Use the slpq as that must be unused by now. 257 */ 258 void 259 thread_zombie(struct thread *td) 260 { 261 mtx_lock_spin(&zombie_lock); 262 TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq); 263 mtx_unlock_spin(&zombie_lock); 264 } 265 266 /* 267 * Release a thread that has exited after cpu_throw(). 268 */ 269 void 270 thread_stash(struct thread *td) 271 { 272 atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1); 273 thread_zombie(td); 274 } 275 276 /* 277 * Reap zombie kse resource. 278 */ 279 void 280 thread_reap(void) 281 { 282 struct thread *td_first, *td_next; 283 284 /* 285 * Don't even bother to lock if none at this instant, 286 * we really don't care about the next instant.. 287 */ 288 if (!TAILQ_EMPTY(&zombie_threads)) { 289 mtx_lock_spin(&zombie_lock); 290 td_first = TAILQ_FIRST(&zombie_threads); 291 if (td_first) 292 TAILQ_INIT(&zombie_threads); 293 mtx_unlock_spin(&zombie_lock); 294 while (td_first) { 295 td_next = TAILQ_NEXT(td_first, td_slpq); 296 if (td_first->td_ucred) 297 crfree(td_first->td_ucred); 298 thread_free(td_first); 299 td_first = td_next; 300 } 301 } 302 } 303 304 /* 305 * Allocate a thread. 306 */ 307 struct thread * 308 thread_alloc(void) 309 { 310 311 thread_reap(); /* check if any zombies to get */ 312 return (uma_zalloc(thread_zone, M_WAITOK)); 313 } 314 315 316 /* 317 * Deallocate a thread. 318 */ 319 void 320 thread_free(struct thread *td) 321 { 322 323 cpu_thread_clean(td); 324 uma_zfree(thread_zone, td); 325 } 326 327 /* 328 * Discard the current thread and exit from its context. 329 * Always called with scheduler locked. 330 * 331 * Because we can't free a thread while we're operating under its context, 332 * push the current thread into our CPU's deadthread holder. This means 333 * we needn't worry about someone else grabbing our context before we 334 * do a cpu_throw(). This may not be needed now as we are under schedlock. 335 * Maybe we can just do a thread_stash() as thr_exit1 does. 336 */ 337 /* XXX 338 * libthr expects its thread exit to return for the last 339 * thread, meaning that the program is back to non-threaded 340 * mode I guess. Because we do this (cpu_throw) unconditionally 341 * here, they have their own version of it. (thr_exit1()) 342 * that doesn't do it all if this was the last thread. 343 * It is also called from thread_suspend_check(). 344 * Of course in the end, they end up coming here through exit1 345 * anyhow.. After fixing 'thr' to play by the rules we should be able 346 * to merge these two functions together. 347 * 348 * called from: 349 * exit1() 350 * kse_exit() 351 * thr_exit() 352 * ifdef KSE 353 * thread_user_enter() 354 * thread_userret() 355 * endif 356 * thread_suspend_check() 357 */ 358 void 359 thread_exit(void) 360 { 361 uint64_t new_switchtime; 362 struct thread *td; 363 struct thread *td2; 364 struct proc *p; 365 366 td = curthread; 367 p = td->td_proc; 368 369 PROC_SLOCK_ASSERT(p, MA_OWNED); 370 mtx_assert(&Giant, MA_NOTOWNED); 371 372 PROC_LOCK_ASSERT(p, MA_OWNED); 373 KASSERT(p != NULL, ("thread exiting without a process")); 374 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 375 (long)p->p_pid, p->p_comm); 376 KASSERT(TAILQ_EMPTY(&td->td_sigqueue.sq_list), ("signal pending")); 377 378 #ifdef AUDIT 379 AUDIT_SYSCALL_EXIT(0, td); 380 #endif 381 382 #ifdef KSE 383 if (td->td_standin != NULL) { 384 /* 385 * Note that we don't need to free the cred here as it 386 * is done in thread_reap(). 387 */ 388 thread_zombie(td->td_standin); 389 td->td_standin = NULL; 390 } 391 #endif 392 393 umtx_thread_exit(td); 394 395 /* 396 * drop FPU & debug register state storage, or any other 397 * architecture specific resources that 398 * would not be on a new untouched process. 399 */ 400 cpu_thread_exit(td); /* XXXSMP */ 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 PCPU_SET(switchtime, new_switchtime); 406 PCPU_SET(switchticks, ticks); 407 PCPU_INC(cnt.v_swtch); 408 /* Save our resource usage in our process. */ 409 td->td_ru.ru_nvcsw++; 410 rucollect(&p->p_ru, &td->td_ru); 411 /* 412 * The last thread is left attached to the process 413 * So that the whole bundle gets recycled. Skip 414 * all this stuff if we never had threads. 415 * EXIT clears all sign of other threads when 416 * it goes to single threading, so the last thread always 417 * takes the short path. 418 */ 419 if (p->p_flag & P_HADTHREADS) { 420 if (p->p_numthreads > 1) { 421 thread_lock(td); 422 #ifdef KSE 423 kse_unlink(td); 424 #else 425 thread_unlink(td); 426 #endif 427 thread_unlock(td); 428 td2 = FIRST_THREAD_IN_PROC(p); 429 sched_exit_thread(td2, td); 430 431 /* 432 * The test below is NOT true if we are the 433 * sole exiting thread. P_STOPPED_SNGL is unset 434 * in exit1() after it is the only survivor. 435 */ 436 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 437 if (p->p_numthreads == p->p_suspcount) { 438 thread_lock(p->p_singlethread); 439 thread_unsuspend_one(p->p_singlethread); 440 thread_unlock(p->p_singlethread); 441 } 442 } 443 444 atomic_add_int(&td->td_proc->p_exitthreads, 1); 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 /* Save our tick information with both the thread and proc locked */ 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 td = FIRST_THREAD_IN_PROC(p); 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 /* Lock the last thread so we spin until it exits cpu_throw(). */ 498 thread_lock(td); 499 thread_unlock(td); 500 /* Wait for any remaining threads to exit cpu_throw(). */ 501 while (p->p_exitthreads) 502 sched_relinquish(curthread); 503 cpu_thread_clean(td); 504 crfree(td->td_ucred); 505 thread_reap(); /* check for zombie threads etc. */ 506 } 507 508 /* 509 * Link a thread to a process. 510 * set up anything that needs to be initialized for it to 511 * be used by the process. 512 * 513 * Note that we do not link to the proc's ucred here. 514 * The thread is linked as if running but no KSE assigned. 515 * Called from: 516 * proc_linkup() 517 * thread_schedule_upcall() 518 * thr_create() 519 */ 520 void 521 thread_link(struct thread *td, struct proc *p) 522 { 523 524 /* 525 * XXX This can't be enabled because it's called for proc0 before 526 * it's spinlock has been created. 527 * PROC_SLOCK_ASSERT(p, MA_OWNED); 528 */ 529 td->td_state = TDS_INACTIVE; 530 td->td_proc = p; 531 td->td_flags = 0; 532 533 LIST_INIT(&td->td_contested); 534 sigqueue_init(&td->td_sigqueue, p); 535 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 536 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 537 p->p_numthreads++; 538 } 539 540 /* 541 * Convert a process with one thread to an unthreaded process. 542 * Called from: 543 * thread_single(exit) (called from execve and exit) 544 * kse_exit() XXX may need cleaning up wrt KSE stuff 545 */ 546 void 547 thread_unthread(struct thread *td) 548 { 549 struct proc *p = td->td_proc; 550 551 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 552 #ifdef KSE 553 upcall_remove(td); 554 p->p_flag &= ~(P_SA|P_HADTHREADS); 555 td->td_mailbox = NULL; 556 td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND); 557 if (td->td_standin != NULL) { 558 thread_zombie(td->td_standin); 559 td->td_standin = NULL; 560 } 561 #else 562 p->p_flag &= ~P_HADTHREADS; 563 #endif 564 } 565 566 /* 567 * Called from: 568 * thread_exit() 569 */ 570 void 571 thread_unlink(struct thread *td) 572 { 573 struct proc *p = td->td_proc; 574 575 PROC_SLOCK_ASSERT(p, MA_OWNED); 576 TAILQ_REMOVE(&p->p_threads, td, td_plist); 577 p->p_numthreads--; 578 /* could clear a few other things here */ 579 /* Must NOT clear links to proc! */ 580 } 581 582 /* 583 * Enforce single-threading. 584 * 585 * Returns 1 if the caller must abort (another thread is waiting to 586 * exit the process or similar). Process is locked! 587 * Returns 0 when you are successfully the only thread running. 588 * A process has successfully single threaded in the suspend mode when 589 * There are no threads in user mode. Threads in the kernel must be 590 * allowed to continue until they get to the user boundary. They may even 591 * copy out their return values and data before suspending. They may however be 592 * accelerated in reaching the user boundary as we will wake up 593 * any sleeping threads that are interruptable. (PCATCH). 594 */ 595 int 596 thread_single(int mode) 597 { 598 struct thread *td; 599 struct thread *td2; 600 struct proc *p; 601 int remaining; 602 603 td = curthread; 604 p = td->td_proc; 605 mtx_assert(&Giant, MA_NOTOWNED); 606 PROC_LOCK_ASSERT(p, MA_OWNED); 607 KASSERT((td != NULL), ("curthread is NULL")); 608 609 if ((p->p_flag & P_HADTHREADS) == 0) 610 return (0); 611 612 /* Is someone already single threading? */ 613 if (p->p_singlethread != NULL && p->p_singlethread != td) 614 return (1); 615 616 if (mode == SINGLE_EXIT) { 617 p->p_flag |= P_SINGLE_EXIT; 618 p->p_flag &= ~P_SINGLE_BOUNDARY; 619 } else { 620 p->p_flag &= ~P_SINGLE_EXIT; 621 if (mode == SINGLE_BOUNDARY) 622 p->p_flag |= P_SINGLE_BOUNDARY; 623 else 624 p->p_flag &= ~P_SINGLE_BOUNDARY; 625 } 626 p->p_flag |= P_STOPPED_SINGLE; 627 PROC_SLOCK(p); 628 p->p_singlethread = td; 629 if (mode == SINGLE_EXIT) 630 remaining = p->p_numthreads; 631 else if (mode == SINGLE_BOUNDARY) 632 remaining = p->p_numthreads - p->p_boundary_count; 633 else 634 remaining = p->p_numthreads - p->p_suspcount; 635 while (remaining != 1) { 636 if (P_SHOULDSTOP(p) != P_STOPPED_SINGLE) 637 goto stopme; 638 FOREACH_THREAD_IN_PROC(p, td2) { 639 if (td2 == td) 640 continue; 641 thread_lock(td2); 642 td2->td_flags |= TDF_ASTPENDING; 643 if (TD_IS_INHIBITED(td2)) { 644 switch (mode) { 645 case SINGLE_EXIT: 646 if (td->td_flags & TDF_DBSUSPEND) 647 td->td_flags &= ~TDF_DBSUSPEND; 648 if (TD_IS_SUSPENDED(td2)) 649 thread_unsuspend_one(td2); 650 if (TD_ON_SLEEPQ(td2) && 651 (td2->td_flags & TDF_SINTR)) 652 sleepq_abort(td2, EINTR); 653 break; 654 case SINGLE_BOUNDARY: 655 if (TD_IS_SUSPENDED(td2) && 656 !(td2->td_flags & TDF_BOUNDARY)) 657 thread_unsuspend_one(td2); 658 if (TD_ON_SLEEPQ(td2) && 659 (td2->td_flags & TDF_SINTR)) 660 sleepq_abort(td2, ERESTART); 661 break; 662 default: 663 if (TD_IS_SUSPENDED(td2)) { 664 thread_unlock(td2); 665 continue; 666 } 667 /* 668 * maybe other inhibited states too? 669 */ 670 if ((td2->td_flags & TDF_SINTR) && 671 (td2->td_inhibitors & 672 (TDI_SLEEPING | TDI_SWAPPED))) 673 thread_suspend_one(td2); 674 break; 675 } 676 } 677 #ifdef SMP 678 else if (TD_IS_RUNNING(td2) && td != td2) { 679 forward_signal(td2); 680 } 681 #endif 682 thread_unlock(td2); 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_suspend_switch(td); 703 if (mode == SINGLE_EXIT) 704 remaining = p->p_numthreads; 705 else if (mode == SINGLE_BOUNDARY) 706 remaining = p->p_numthreads - p->p_boundary_count; 707 else 708 remaining = p->p_numthreads - p->p_suspcount; 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; 763 764 td = curthread; 765 p = td->td_proc; 766 mtx_assert(&Giant, MA_NOTOWNED); 767 PROC_LOCK_ASSERT(p, MA_OWNED); 768 while (P_SHOULDSTOP(p) || 769 ((p->p_flag & P_TRACED) && (td->td_flags & TDF_DBSUSPEND))) { 770 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 771 KASSERT(p->p_singlethread != NULL, 772 ("singlethread not set")); 773 /* 774 * The only suspension in action is a 775 * single-threading. Single threader need not stop. 776 * XXX Should be safe to access unlocked 777 * as it can only be set to be true by us. 778 */ 779 if (p->p_singlethread == td) 780 return (0); /* Exempt from stopping. */ 781 } 782 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 783 return (EINTR); 784 785 /* Should we goto user boundary if we didn't come from there? */ 786 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 787 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 788 return (ERESTART); 789 790 /* If thread will exit, flush its pending signals */ 791 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 792 sigqueue_flush(&td->td_sigqueue); 793 794 PROC_SLOCK(p); 795 thread_stopped(p); 796 /* 797 * If the process is waiting for us to exit, 798 * this thread should just suicide. 799 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 800 */ 801 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 802 thread_exit(); 803 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 804 if (p->p_numthreads == p->p_suspcount + 1) { 805 thread_lock(p->p_singlethread); 806 thread_unsuspend_one(p->p_singlethread); 807 thread_unlock(p->p_singlethread); 808 } 809 } 810 PROC_UNLOCK(p); 811 thread_lock(td); 812 /* 813 * When a thread suspends, it just 814 * gets taken off all queues. 815 */ 816 thread_suspend_one(td); 817 if (return_instead == 0) { 818 p->p_boundary_count++; 819 td->td_flags |= TDF_BOUNDARY; 820 } 821 PROC_SUNLOCK(p); 822 mi_switch(SW_INVOL, NULL); 823 if (return_instead == 0) 824 td->td_flags &= ~TDF_BOUNDARY; 825 thread_unlock(td); 826 PROC_LOCK(p); 827 if (return_instead == 0) 828 p->p_boundary_count--; 829 } 830 return (0); 831 } 832 833 void 834 thread_suspend_switch(struct thread *td) 835 { 836 struct proc *p; 837 838 p = td->td_proc; 839 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 840 PROC_LOCK_ASSERT(p, MA_OWNED); 841 PROC_SLOCK_ASSERT(p, MA_OWNED); 842 /* 843 * We implement thread_suspend_one in stages here to avoid 844 * dropping the proc lock while the thread lock is owned. 845 */ 846 thread_stopped(p); 847 p->p_suspcount++; 848 PROC_UNLOCK(p); 849 thread_lock(td); 850 TD_SET_SUSPENDED(td); 851 PROC_SUNLOCK(p); 852 DROP_GIANT(); 853 mi_switch(SW_VOL, NULL); 854 thread_unlock(td); 855 PICKUP_GIANT(); 856 PROC_LOCK(p); 857 PROC_SLOCK(p); 858 } 859 860 void 861 thread_suspend_one(struct thread *td) 862 { 863 struct proc *p = td->td_proc; 864 865 PROC_SLOCK_ASSERT(p, MA_OWNED); 866 THREAD_LOCK_ASSERT(td, MA_OWNED); 867 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 868 p->p_suspcount++; 869 TD_SET_SUSPENDED(td); 870 } 871 872 void 873 thread_unsuspend_one(struct thread *td) 874 { 875 struct proc *p = td->td_proc; 876 877 PROC_SLOCK_ASSERT(p, MA_OWNED); 878 THREAD_LOCK_ASSERT(td, MA_OWNED); 879 KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended")); 880 TD_CLR_SUSPENDED(td); 881 p->p_suspcount--; 882 setrunnable(td); 883 } 884 885 /* 886 * Allow all threads blocked by single threading to continue running. 887 */ 888 void 889 thread_unsuspend(struct proc *p) 890 { 891 struct thread *td; 892 893 PROC_LOCK_ASSERT(p, MA_OWNED); 894 PROC_SLOCK_ASSERT(p, MA_OWNED); 895 if (!P_SHOULDSTOP(p)) { 896 FOREACH_THREAD_IN_PROC(p, td) { 897 thread_lock(td); 898 if (TD_IS_SUSPENDED(td)) { 899 thread_unsuspend_one(td); 900 } 901 thread_unlock(td); 902 } 903 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 904 (p->p_numthreads == p->p_suspcount)) { 905 /* 906 * Stopping everything also did the job for the single 907 * threading request. Now we've downgraded to single-threaded, 908 * let it continue. 909 */ 910 thread_lock(p->p_singlethread); 911 thread_unsuspend_one(p->p_singlethread); 912 thread_unlock(p->p_singlethread); 913 } 914 } 915 916 /* 917 * End the single threading mode.. 918 */ 919 void 920 thread_single_end(void) 921 { 922 struct thread *td; 923 struct proc *p; 924 925 td = curthread; 926 p = td->td_proc; 927 PROC_LOCK_ASSERT(p, MA_OWNED); 928 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 929 PROC_SLOCK(p); 930 p->p_singlethread = NULL; 931 /* 932 * If there are other threads they mey now run, 933 * unless of course there is a blanket 'stop order' 934 * on the process. The single threader must be allowed 935 * to continue however as this is a bad place to stop. 936 */ 937 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 938 FOREACH_THREAD_IN_PROC(p, td) { 939 thread_lock(td); 940 if (TD_IS_SUSPENDED(td)) { 941 thread_unsuspend_one(td); 942 } 943 thread_unlock(td); 944 } 945 } 946 PROC_SUNLOCK(p); 947 } 948 949 struct thread * 950 thread_find(struct proc *p, lwpid_t tid) 951 { 952 struct thread *td; 953 954 PROC_LOCK_ASSERT(p, MA_OWNED); 955 PROC_SLOCK(p); 956 FOREACH_THREAD_IN_PROC(p, td) { 957 if (td->td_tid == tid) 958 break; 959 } 960 PROC_SUNLOCK(p); 961 return (td); 962 } 963