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/smp.h> 39 #include <sys/sysctl.h> 40 #include <sys/sched.h> 41 #include <sys/sleepqueue.h> 42 #include <sys/turnstile.h> 43 #include <sys/ktr.h> 44 #include <sys/umtx.h> 45 46 #include <vm/vm.h> 47 #include <vm/vm_extern.h> 48 #include <vm/uma.h> 49 50 /* 51 * KSEGRP related storage. 52 */ 53 static uma_zone_t ksegrp_zone; 54 static uma_zone_t thread_zone; 55 56 /* DEBUG ONLY */ 57 SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation"); 58 static int thread_debug = 0; 59 SYSCTL_INT(_kern_threads, OID_AUTO, debug, CTLFLAG_RW, 60 &thread_debug, 0, "thread debug"); 61 62 int max_threads_per_proc = 1500; 63 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW, 64 &max_threads_per_proc, 0, "Limit on threads per proc"); 65 66 int max_groups_per_proc = 1500; 67 SYSCTL_INT(_kern_threads, OID_AUTO, max_groups_per_proc, CTLFLAG_RW, 68 &max_groups_per_proc, 0, "Limit on thread groups per proc"); 69 70 int max_threads_hits; 71 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD, 72 &max_threads_hits, 0, ""); 73 74 int virtual_cpu; 75 76 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 77 TAILQ_HEAD(, ksegrp) zombie_ksegrps = TAILQ_HEAD_INITIALIZER(zombie_ksegrps); 78 struct mtx kse_zombie_lock; 79 MTX_SYSINIT(kse_zombie_lock, &kse_zombie_lock, "kse zombie lock", MTX_SPIN); 80 81 static int 82 sysctl_kse_virtual_cpu(SYSCTL_HANDLER_ARGS) 83 { 84 int error, new_val; 85 int def_val; 86 87 def_val = mp_ncpus; 88 if (virtual_cpu == 0) 89 new_val = def_val; 90 else 91 new_val = virtual_cpu; 92 error = sysctl_handle_int(oidp, &new_val, 0, req); 93 if (error != 0 || req->newptr == NULL) 94 return (error); 95 if (new_val < 0) 96 return (EINVAL); 97 virtual_cpu = new_val; 98 return (0); 99 } 100 101 /* DEBUG ONLY */ 102 SYSCTL_PROC(_kern_threads, OID_AUTO, virtual_cpu, CTLTYPE_INT|CTLFLAG_RW, 103 0, sizeof(virtual_cpu), sysctl_kse_virtual_cpu, "I", 104 "debug virtual cpus"); 105 106 struct mtx tid_lock; 107 static struct unrhdr *tid_unrhdr; 108 109 /* 110 * Prepare a thread for use. 111 */ 112 static int 113 thread_ctor(void *mem, int size, void *arg, int flags) 114 { 115 struct thread *td; 116 117 td = (struct thread *)mem; 118 td->td_state = TDS_INACTIVE; 119 td->td_oncpu = NOCPU; 120 121 td->td_tid = alloc_unr(tid_unrhdr); 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. A context switch must occur inside a 127 * critical section, and in fact, includes hand-off of the sched_lock. 128 * After a context switch to a newly created thread, it will release 129 * sched_lock for the first time, and its td_critnest will hit 0 for 130 * the first time. This happens on the far end of a context switch, 131 * and when it context switches away from itself, it will in fact go 132 * back into a critical section, and hand off the sched lock to the 133 * next thread. 134 */ 135 td->td_critnest = 1; 136 return (0); 137 } 138 139 /* 140 * Reclaim a thread after use. 141 */ 142 static void 143 thread_dtor(void *mem, int size, void *arg) 144 { 145 struct thread *td; 146 147 td = (struct thread *)mem; 148 149 #ifdef INVARIANTS 150 /* Verify that this thread is in a safe state to free. */ 151 switch (td->td_state) { 152 case TDS_INHIBITED: 153 case TDS_RUNNING: 154 case TDS_CAN_RUN: 155 case TDS_RUNQ: 156 /* 157 * We must never unlink a thread that is in one of 158 * these states, because it is currently active. 159 */ 160 panic("bad state for thread unlinking"); 161 /* NOTREACHED */ 162 case TDS_INACTIVE: 163 break; 164 default: 165 panic("bad thread state"); 166 /* NOTREACHED */ 167 } 168 #endif 169 170 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_umtxq = umtxq_alloc(); 189 td->td_sched = (struct td_sched *)&td[1]; 190 sched_newthread(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 umtxq_free(td->td_umtxq); 206 vm_thread_dispose(td); 207 } 208 209 /* 210 * Initialize type-stable parts of a ksegrp (when newly created). 211 */ 212 static int 213 ksegrp_ctor(void *mem, int size, void *arg, int flags) 214 { 215 struct ksegrp *kg; 216 217 kg = (struct ksegrp *)mem; 218 bzero(mem, size); 219 kg->kg_sched = (struct kg_sched *)&kg[1]; 220 return (0); 221 } 222 223 void 224 ksegrp_link(struct ksegrp *kg, struct proc *p) 225 { 226 227 TAILQ_INIT(&kg->kg_threads); 228 TAILQ_INIT(&kg->kg_runq); /* links with td_runq */ 229 TAILQ_INIT(&kg->kg_upcalls); /* all upcall structure in ksegrp */ 230 kg->kg_proc = p; 231 /* 232 * the following counters are in the -zero- section 233 * and may not need clearing 234 */ 235 kg->kg_numthreads = 0; 236 kg->kg_numupcalls = 0; 237 /* link it in now that it's consistent */ 238 p->p_numksegrps++; 239 TAILQ_INSERT_HEAD(&p->p_ksegrps, kg, kg_ksegrp); 240 } 241 242 /* 243 * Called from: 244 * thread-exit() 245 */ 246 void 247 ksegrp_unlink(struct ksegrp *kg) 248 { 249 struct proc *p; 250 251 mtx_assert(&sched_lock, MA_OWNED); 252 KASSERT((kg->kg_numthreads == 0), ("ksegrp_unlink: residual threads")); 253 KASSERT((kg->kg_numupcalls == 0), ("ksegrp_unlink: residual upcalls")); 254 255 p = kg->kg_proc; 256 TAILQ_REMOVE(&p->p_ksegrps, kg, kg_ksegrp); 257 p->p_numksegrps--; 258 /* 259 * Aggregate stats from the KSE 260 */ 261 if (p->p_procscopegrp == kg) 262 p->p_procscopegrp = NULL; 263 } 264 265 /* 266 * For a newly created process, 267 * link up all the structures and its initial threads etc. 268 * called from: 269 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 270 * proc_dtor() (should go away) 271 * proc_init() 272 */ 273 void 274 proc_linkup(struct proc *p, struct ksegrp *kg, struct thread *td) 275 { 276 277 TAILQ_INIT(&p->p_ksegrps); /* all ksegrps in proc */ 278 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 279 TAILQ_INIT(&p->p_suspended); /* Threads suspended */ 280 p->p_numksegrps = 0; 281 p->p_numthreads = 0; 282 283 ksegrp_link(kg, p); 284 thread_link(td, kg); 285 } 286 287 /* 288 * Initialize global thread allocation resources. 289 */ 290 void 291 threadinit(void) 292 { 293 294 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 295 tid_unrhdr = new_unrhdr(PID_MAX + 1, INT_MAX, &tid_lock); 296 297 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 298 thread_ctor, thread_dtor, thread_init, thread_fini, 299 UMA_ALIGN_CACHE, 0); 300 ksegrp_zone = uma_zcreate("KSEGRP", sched_sizeof_ksegrp(), 301 ksegrp_ctor, NULL, NULL, NULL, 302 UMA_ALIGN_CACHE, 0); 303 kseinit(); /* set up kse specific stuff e.g. upcall zone*/ 304 } 305 306 /* 307 * Stash an embarasingly extra thread into the zombie thread queue. 308 */ 309 void 310 thread_stash(struct thread *td) 311 { 312 mtx_lock_spin(&kse_zombie_lock); 313 TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq); 314 mtx_unlock_spin(&kse_zombie_lock); 315 } 316 317 /* 318 * Stash an embarasingly extra ksegrp into the zombie ksegrp queue. 319 */ 320 void 321 ksegrp_stash(struct ksegrp *kg) 322 { 323 mtx_lock_spin(&kse_zombie_lock); 324 TAILQ_INSERT_HEAD(&zombie_ksegrps, kg, kg_ksegrp); 325 mtx_unlock_spin(&kse_zombie_lock); 326 } 327 328 /* 329 * Reap zombie kse resource. 330 */ 331 void 332 thread_reap(void) 333 { 334 struct thread *td_first, *td_next; 335 struct ksegrp *kg_first, * kg_next; 336 337 /* 338 * Don't even bother to lock if none at this instant, 339 * we really don't care about the next instant.. 340 */ 341 if ((!TAILQ_EMPTY(&zombie_threads)) 342 || (!TAILQ_EMPTY(&zombie_ksegrps))) { 343 mtx_lock_spin(&kse_zombie_lock); 344 td_first = TAILQ_FIRST(&zombie_threads); 345 kg_first = TAILQ_FIRST(&zombie_ksegrps); 346 if (td_first) 347 TAILQ_INIT(&zombie_threads); 348 if (kg_first) 349 TAILQ_INIT(&zombie_ksegrps); 350 mtx_unlock_spin(&kse_zombie_lock); 351 while (td_first) { 352 td_next = TAILQ_NEXT(td_first, td_runq); 353 if (td_first->td_ucred) 354 crfree(td_first->td_ucred); 355 thread_free(td_first); 356 td_first = td_next; 357 } 358 while (kg_first) { 359 kg_next = TAILQ_NEXT(kg_first, kg_ksegrp); 360 ksegrp_free(kg_first); 361 kg_first = kg_next; 362 } 363 /* 364 * there will always be a thread on the list if one of these 365 * is there. 366 */ 367 kse_GC(); 368 } 369 } 370 371 /* 372 * Allocate a ksegrp. 373 */ 374 struct ksegrp * 375 ksegrp_alloc(void) 376 { 377 return (uma_zalloc(ksegrp_zone, M_WAITOK)); 378 } 379 380 /* 381 * Allocate a thread. 382 */ 383 struct thread * 384 thread_alloc(void) 385 { 386 thread_reap(); /* check if any zombies to get */ 387 return (uma_zalloc(thread_zone, M_WAITOK)); 388 } 389 390 /* 391 * Deallocate a ksegrp. 392 */ 393 void 394 ksegrp_free(struct ksegrp *td) 395 { 396 uma_zfree(ksegrp_zone, td); 397 } 398 399 /* 400 * Deallocate a thread. 401 */ 402 void 403 thread_free(struct thread *td) 404 { 405 406 cpu_thread_clean(td); 407 uma_zfree(thread_zone, td); 408 } 409 410 /* 411 * Discard the current thread and exit from its context. 412 * Always called with scheduler locked. 413 * 414 * Because we can't free a thread while we're operating under its context, 415 * push the current thread into our CPU's deadthread holder. This means 416 * we needn't worry about someone else grabbing our context before we 417 * do a cpu_throw(). This may not be needed now as we are under schedlock. 418 * Maybe we can just do a thread_stash() as thr_exit1 does. 419 */ 420 /* XXX 421 * libthr expects its thread exit to return for the last 422 * thread, meaning that the program is back to non-threaded 423 * mode I guess. Because we do this (cpu_throw) unconditionally 424 * here, they have their own version of it. (thr_exit1()) 425 * that doesn't do it all if this was the last thread. 426 * It is also called from thread_suspend_check(). 427 * Of course in the end, they end up coming here through exit1 428 * anyhow.. After fixing 'thr' to play by the rules we should be able 429 * to merge these two functions together. 430 * 431 * called from: 432 * exit1() 433 * kse_exit() 434 * thr_exit() 435 * thread_user_enter() 436 * thread_userret() 437 * thread_suspend_check() 438 */ 439 void 440 thread_exit(void) 441 { 442 struct thread *td; 443 struct proc *p; 444 struct ksegrp *kg; 445 446 td = curthread; 447 kg = td->td_ksegrp; 448 p = td->td_proc; 449 450 mtx_assert(&sched_lock, MA_OWNED); 451 mtx_assert(&Giant, MA_NOTOWNED); 452 PROC_LOCK_ASSERT(p, MA_OWNED); 453 KASSERT(p != NULL, ("thread exiting without a process")); 454 KASSERT(kg != NULL, ("thread exiting without a kse group")); 455 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 456 (long)p->p_pid, p->p_comm); 457 458 if (td->td_standin != NULL) { 459 /* 460 * Note that we don't need to free the cred here as it 461 * is done in thread_reap(). 462 */ 463 thread_stash(td->td_standin); 464 td->td_standin = NULL; 465 } 466 467 /* 468 * drop FPU & debug register state storage, or any other 469 * architecture specific resources that 470 * would not be on a new untouched process. 471 */ 472 cpu_thread_exit(td); /* XXXSMP */ 473 474 /* 475 * The thread is exiting. scheduler can release its stuff 476 * and collect stats etc. 477 */ 478 sched_thread_exit(td); 479 480 /* 481 * The last thread is left attached to the process 482 * So that the whole bundle gets recycled. Skip 483 * all this stuff if we never had threads. 484 * EXIT clears all sign of other threads when 485 * it goes to single threading, so the last thread always 486 * takes the short path. 487 */ 488 if (p->p_flag & P_HADTHREADS) { 489 if (p->p_numthreads > 1) { 490 thread_unlink(td); 491 492 /* XXX first arg not used in 4BSD or ULE */ 493 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 494 495 /* 496 * The test below is NOT true if we are the 497 * sole exiting thread. P_STOPPED_SNGL is unset 498 * in exit1() after it is the only survivor. 499 */ 500 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 501 if (p->p_numthreads == p->p_suspcount) { 502 thread_unsuspend_one(p->p_singlethread); 503 } 504 } 505 506 /* 507 * Because each upcall structure has an owner thread, 508 * owner thread exits only when process is in exiting 509 * state, so upcall to userland is no longer needed, 510 * deleting upcall structure is safe here. 511 * So when all threads in a group is exited, all upcalls 512 * in the group should be automatically freed. 513 * XXXKSE This is a KSE thing and should be exported 514 * there somehow. 515 */ 516 upcall_remove(td); 517 518 /* 519 * If the thread we unlinked above was the last one, 520 * then this ksegrp should go away too. 521 */ 522 if (kg->kg_numthreads == 0) { 523 /* 524 * let the scheduler know about this in case 525 * it needs to recover stats or resources. 526 * Theoretically we could let 527 * sched_exit_ksegrp() do the equivalent of 528 * setting the concurrency to 0 529 * but don't do it yet to avoid changing 530 * the existing scheduler code until we 531 * are ready. 532 * We supply a random other ksegrp 533 * as the recipient of any built up 534 * cpu usage etc. (If the scheduler wants it). 535 * XXXKSE 536 * This is probably not fair so think of 537 * a better answer. 538 */ 539 sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), td); 540 sched_set_concurrency(kg, 0); /* XXX TEMP */ 541 ksegrp_unlink(kg); 542 ksegrp_stash(kg); 543 } 544 PROC_UNLOCK(p); 545 td->td_ksegrp = NULL; 546 PCPU_SET(deadthread, td); 547 } else { 548 /* 549 * The last thread is exiting.. but not through exit() 550 * what should we do? 551 * Theoretically this can't happen 552 * exit1() - clears threading flags before coming here 553 * kse_exit() - treats last thread specially 554 * thr_exit() - treats last thread specially 555 * thread_user_enter() - only if more exist 556 * thread_userret() - only if more exist 557 * thread_suspend_check() - only if more exist 558 */ 559 panic ("thread_exit: Last thread exiting on its own"); 560 } 561 } else { 562 /* 563 * non threaded process comes here. 564 * This includes an EX threaded process that is coming 565 * here via exit1(). (exit1 dethreads the proc first). 566 */ 567 PROC_UNLOCK(p); 568 } 569 td->td_state = TDS_INACTIVE; 570 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 571 cpu_throw(td, choosethread()); 572 panic("I'm a teapot!"); 573 /* NOTREACHED */ 574 } 575 576 /* 577 * Do any thread specific cleanups that may be needed in wait() 578 * called with Giant, proc and schedlock not held. 579 */ 580 void 581 thread_wait(struct proc *p) 582 { 583 struct thread *td; 584 585 mtx_assert(&Giant, MA_NOTOWNED); 586 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 587 KASSERT((p->p_numksegrps == 1), ("Multiple ksegrps in wait1()")); 588 FOREACH_THREAD_IN_PROC(p, td) { 589 if (td->td_standin != NULL) { 590 if (td->td_standin->td_ucred != NULL) { 591 crfree(td->td_standin->td_ucred); 592 td->td_standin->td_ucred = NULL; 593 } 594 thread_free(td->td_standin); 595 td->td_standin = NULL; 596 } 597 cpu_thread_clean(td); 598 crfree(td->td_ucred); 599 } 600 thread_reap(); /* check for zombie threads etc. */ 601 } 602 603 /* 604 * Link a thread to a process. 605 * set up anything that needs to be initialized for it to 606 * be used by the process. 607 * 608 * Note that we do not link to the proc's ucred here. 609 * The thread is linked as if running but no KSE assigned. 610 * Called from: 611 * proc_linkup() 612 * thread_schedule_upcall() 613 * thr_create() 614 */ 615 void 616 thread_link(struct thread *td, struct ksegrp *kg) 617 { 618 struct proc *p; 619 620 p = kg->kg_proc; 621 td->td_state = TDS_INACTIVE; 622 td->td_proc = p; 623 td->td_ksegrp = kg; 624 td->td_flags = 0; 625 td->td_kflags = 0; 626 627 LIST_INIT(&td->td_contested); 628 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 629 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 630 TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist); 631 p->p_numthreads++; 632 kg->kg_numthreads++; 633 } 634 635 /* 636 * Convert a process with one thread to an unthreaded process. 637 * Called from: 638 * thread_single(exit) (called from execve and exit) 639 * kse_exit() XXX may need cleaning up wrt KSE stuff 640 */ 641 void 642 thread_unthread(struct thread *td) 643 { 644 struct proc *p = td->td_proc; 645 646 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 647 upcall_remove(td); 648 p->p_flag &= ~(P_SA|P_HADTHREADS); 649 td->td_mailbox = NULL; 650 td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND); 651 if (td->td_standin != NULL) { 652 thread_stash(td->td_standin); 653 td->td_standin = NULL; 654 } 655 sched_set_concurrency(td->td_ksegrp, 1); 656 } 657 658 /* 659 * Called from: 660 * thread_exit() 661 */ 662 void 663 thread_unlink(struct thread *td) 664 { 665 struct proc *p = td->td_proc; 666 struct ksegrp *kg = td->td_ksegrp; 667 668 mtx_assert(&sched_lock, MA_OWNED); 669 TAILQ_REMOVE(&p->p_threads, td, td_plist); 670 p->p_numthreads--; 671 TAILQ_REMOVE(&kg->kg_threads, td, td_kglist); 672 kg->kg_numthreads--; 673 /* could clear a few other things here */ 674 /* Must NOT clear links to proc and ksegrp! */ 675 } 676 677 /* 678 * Enforce single-threading. 679 * 680 * Returns 1 if the caller must abort (another thread is waiting to 681 * exit the process or similar). Process is locked! 682 * Returns 0 when you are successfully the only thread running. 683 * A process has successfully single threaded in the suspend mode when 684 * There are no threads in user mode. Threads in the kernel must be 685 * allowed to continue until they get to the user boundary. They may even 686 * copy out their return values and data before suspending. They may however be 687 * accellerated in reaching the user boundary as we will wake up 688 * any sleeping threads that are interruptable. (PCATCH). 689 */ 690 int 691 thread_single(int mode) 692 { 693 struct thread *td; 694 struct thread *td2; 695 struct proc *p; 696 int remaining; 697 698 td = curthread; 699 p = td->td_proc; 700 mtx_assert(&Giant, MA_NOTOWNED); 701 PROC_LOCK_ASSERT(p, MA_OWNED); 702 KASSERT((td != NULL), ("curthread is NULL")); 703 704 if ((p->p_flag & P_HADTHREADS) == 0) 705 return (0); 706 707 /* Is someone already single threading? */ 708 if (p->p_singlethread != NULL && p->p_singlethread != td) 709 return (1); 710 711 if (mode == SINGLE_EXIT) { 712 p->p_flag |= P_SINGLE_EXIT; 713 p->p_flag &= ~P_SINGLE_BOUNDARY; 714 } else { 715 p->p_flag &= ~P_SINGLE_EXIT; 716 if (mode == SINGLE_BOUNDARY) 717 p->p_flag |= P_SINGLE_BOUNDARY; 718 else 719 p->p_flag &= ~P_SINGLE_BOUNDARY; 720 } 721 p->p_flag |= P_STOPPED_SINGLE; 722 mtx_lock_spin(&sched_lock); 723 p->p_singlethread = td; 724 if (mode == SINGLE_EXIT) 725 remaining = p->p_numthreads; 726 else if (mode == SINGLE_BOUNDARY) 727 remaining = p->p_numthreads - p->p_boundary_count; 728 else 729 remaining = p->p_numthreads - p->p_suspcount; 730 while (remaining != 1) { 731 FOREACH_THREAD_IN_PROC(p, td2) { 732 if (td2 == td) 733 continue; 734 td2->td_flags |= TDF_ASTPENDING; 735 if (TD_IS_INHIBITED(td2)) { 736 switch (mode) { 737 case SINGLE_EXIT: 738 if (td->td_flags & TDF_DBSUSPEND) 739 td->td_flags &= ~TDF_DBSUSPEND; 740 if (TD_IS_SUSPENDED(td2)) 741 thread_unsuspend_one(td2); 742 if (TD_ON_SLEEPQ(td2) && 743 (td2->td_flags & TDF_SINTR)) 744 sleepq_abort(td2); 745 break; 746 case SINGLE_BOUNDARY: 747 if (TD_IS_SUSPENDED(td2) && 748 !(td2->td_flags & TDF_BOUNDARY)) 749 thread_unsuspend_one(td2); 750 if (TD_ON_SLEEPQ(td2) && 751 (td2->td_flags & TDF_SINTR)) 752 sleepq_abort(td2); 753 break; 754 default: 755 if (TD_IS_SUSPENDED(td2)) 756 continue; 757 /* 758 * maybe other inhibitted states too? 759 */ 760 if ((td2->td_flags & TDF_SINTR) && 761 (td2->td_inhibitors & 762 (TDI_SLEEPING | TDI_SWAPPED))) 763 thread_suspend_one(td2); 764 break; 765 } 766 } 767 } 768 if (mode == SINGLE_EXIT) 769 remaining = p->p_numthreads; 770 else if (mode == SINGLE_BOUNDARY) 771 remaining = p->p_numthreads - p->p_boundary_count; 772 else 773 remaining = p->p_numthreads - p->p_suspcount; 774 775 /* 776 * Maybe we suspended some threads.. was it enough? 777 */ 778 if (remaining == 1) 779 break; 780 781 /* 782 * Wake us up when everyone else has suspended. 783 * In the mean time we suspend as well. 784 */ 785 thread_suspend_one(td); 786 PROC_UNLOCK(p); 787 mi_switch(SW_VOL, NULL); 788 mtx_unlock_spin(&sched_lock); 789 PROC_LOCK(p); 790 mtx_lock_spin(&sched_lock); 791 if (mode == SINGLE_EXIT) 792 remaining = p->p_numthreads; 793 else if (mode == SINGLE_BOUNDARY) 794 remaining = p->p_numthreads - p->p_boundary_count; 795 else 796 remaining = p->p_numthreads - p->p_suspcount; 797 } 798 if (mode == SINGLE_EXIT) { 799 /* 800 * We have gotten rid of all the other threads and we 801 * are about to either exit or exec. In either case, 802 * we try our utmost to revert to being a non-threaded 803 * process. 804 */ 805 p->p_singlethread = NULL; 806 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 807 thread_unthread(td); 808 } 809 mtx_unlock_spin(&sched_lock); 810 return (0); 811 } 812 813 /* 814 * Called in from locations that can safely check to see 815 * whether we have to suspend or at least throttle for a 816 * single-thread event (e.g. fork). 817 * 818 * Such locations include userret(). 819 * If the "return_instead" argument is non zero, the thread must be able to 820 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 821 * 822 * The 'return_instead' argument tells the function if it may do a 823 * thread_exit() or suspend, or whether the caller must abort and back 824 * out instead. 825 * 826 * If the thread that set the single_threading request has set the 827 * P_SINGLE_EXIT bit in the process flags then this call will never return 828 * if 'return_instead' is false, but will exit. 829 * 830 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 831 *---------------+--------------------+--------------------- 832 * 0 | returns 0 | returns 0 or 1 833 * | when ST ends | immediatly 834 *---------------+--------------------+--------------------- 835 * 1 | thread exits | returns 1 836 * | | immediatly 837 * 0 = thread_exit() or suspension ok, 838 * other = return error instead of stopping the thread. 839 * 840 * While a full suspension is under effect, even a single threading 841 * thread would be suspended if it made this call (but it shouldn't). 842 * This call should only be made from places where 843 * thread_exit() would be safe as that may be the outcome unless 844 * return_instead is set. 845 */ 846 int 847 thread_suspend_check(int return_instead) 848 { 849 struct thread *td; 850 struct proc *p; 851 852 td = curthread; 853 p = td->td_proc; 854 mtx_assert(&Giant, MA_NOTOWNED); 855 PROC_LOCK_ASSERT(p, MA_OWNED); 856 while (P_SHOULDSTOP(p) || 857 ((p->p_flag & P_TRACED) && (td->td_flags & TDF_DBSUSPEND))) { 858 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 859 KASSERT(p->p_singlethread != NULL, 860 ("singlethread not set")); 861 /* 862 * The only suspension in action is a 863 * single-threading. Single threader need not stop. 864 * XXX Should be safe to access unlocked 865 * as it can only be set to be true by us. 866 */ 867 if (p->p_singlethread == td) 868 return (0); /* Exempt from stopping. */ 869 } 870 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 871 return (1); 872 873 /* Should we goto user boundary if we didn't come from there? */ 874 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 875 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 876 return (1); 877 878 mtx_lock_spin(&sched_lock); 879 thread_stopped(p); 880 /* 881 * If the process is waiting for us to exit, 882 * this thread should just suicide. 883 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 884 */ 885 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 886 thread_exit(); 887 888 /* 889 * When a thread suspends, it just 890 * moves to the processes's suspend queue 891 * and stays there. 892 */ 893 thread_suspend_one(td); 894 if (return_instead == 0) { 895 p->p_boundary_count++; 896 td->td_flags |= TDF_BOUNDARY; 897 } 898 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 899 if (p->p_numthreads == p->p_suspcount) 900 thread_unsuspend_one(p->p_singlethread); 901 } 902 PROC_UNLOCK(p); 903 mi_switch(SW_INVOL, NULL); 904 if (return_instead == 0) { 905 p->p_boundary_count--; 906 td->td_flags &= ~TDF_BOUNDARY; 907 } 908 mtx_unlock_spin(&sched_lock); 909 PROC_LOCK(p); 910 } 911 return (0); 912 } 913 914 void 915 thread_suspend_one(struct thread *td) 916 { 917 struct proc *p = td->td_proc; 918 919 mtx_assert(&sched_lock, MA_OWNED); 920 PROC_LOCK_ASSERT(p, MA_OWNED); 921 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 922 p->p_suspcount++; 923 TD_SET_SUSPENDED(td); 924 TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq); 925 } 926 927 void 928 thread_unsuspend_one(struct thread *td) 929 { 930 struct proc *p = td->td_proc; 931 932 mtx_assert(&sched_lock, MA_OWNED); 933 PROC_LOCK_ASSERT(p, MA_OWNED); 934 TAILQ_REMOVE(&p->p_suspended, td, td_runq); 935 TD_CLR_SUSPENDED(td); 936 p->p_suspcount--; 937 setrunnable(td); 938 } 939 940 /* 941 * Allow all threads blocked by single threading to continue running. 942 */ 943 void 944 thread_unsuspend(struct proc *p) 945 { 946 struct thread *td; 947 948 mtx_assert(&sched_lock, MA_OWNED); 949 PROC_LOCK_ASSERT(p, MA_OWNED); 950 if (!P_SHOULDSTOP(p)) { 951 while ((td = TAILQ_FIRST(&p->p_suspended))) { 952 thread_unsuspend_one(td); 953 } 954 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 955 (p->p_numthreads == p->p_suspcount)) { 956 /* 957 * Stopping everything also did the job for the single 958 * threading request. Now we've downgraded to single-threaded, 959 * let it continue. 960 */ 961 thread_unsuspend_one(p->p_singlethread); 962 } 963 } 964 965 /* 966 * End the single threading mode.. 967 */ 968 void 969 thread_single_end(void) 970 { 971 struct thread *td; 972 struct proc *p; 973 974 td = curthread; 975 p = td->td_proc; 976 PROC_LOCK_ASSERT(p, MA_OWNED); 977 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 978 mtx_lock_spin(&sched_lock); 979 p->p_singlethread = NULL; 980 p->p_procscopegrp = NULL; 981 /* 982 * If there are other threads they mey now run, 983 * unless of course there is a blanket 'stop order' 984 * on the process. The single threader must be allowed 985 * to continue however as this is a bad place to stop. 986 */ 987 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 988 while ((td = TAILQ_FIRST(&p->p_suspended))) { 989 thread_unsuspend_one(td); 990 } 991 } 992 mtx_unlock_spin(&sched_lock); 993 } 994 995 /* 996 * Called before going into an interruptible sleep to see if we have been 997 * interrupted or requested to exit. 998 */ 999 int 1000 thread_sleep_check(struct thread *td) 1001 { 1002 struct proc *p; 1003 1004 p = td->td_proc; 1005 mtx_assert(&sched_lock, MA_OWNED); 1006 if (p->p_flag & P_HADTHREADS) { 1007 if (p->p_singlethread != td) { 1008 if (p->p_flag & P_SINGLE_EXIT) 1009 return (EINTR); 1010 if (p->p_flag & P_SINGLE_BOUNDARY) 1011 return (ERESTART); 1012 } 1013 if (td->td_flags & TDF_INTERRUPT) 1014 return (td->td_intrval); 1015 } 1016 return (0); 1017 } 1018