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 } 262 263 /* 264 * For a newly created process, 265 * link up all the structures and its initial threads etc. 266 * called from: 267 * {arch}/{arch}/machdep.c ia64_init(), init386() etc. 268 * proc_dtor() (should go away) 269 * proc_init() 270 */ 271 void 272 proc_linkup(struct proc *p, struct ksegrp *kg, struct thread *td) 273 { 274 275 TAILQ_INIT(&p->p_ksegrps); /* all ksegrps in proc */ 276 TAILQ_INIT(&p->p_threads); /* all threads in proc */ 277 TAILQ_INIT(&p->p_suspended); /* Threads suspended */ 278 p->p_numksegrps = 0; 279 p->p_numthreads = 0; 280 281 ksegrp_link(kg, p); 282 thread_link(td, kg); 283 } 284 285 /* 286 * Initialize global thread allocation resources. 287 */ 288 void 289 threadinit(void) 290 { 291 292 mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF); 293 tid_unrhdr = new_unrhdr(PID_MAX + 1, INT_MAX, &tid_lock); 294 295 thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), 296 thread_ctor, thread_dtor, thread_init, thread_fini, 297 UMA_ALIGN_CACHE, 0); 298 ksegrp_zone = uma_zcreate("KSEGRP", sched_sizeof_ksegrp(), 299 ksegrp_ctor, NULL, NULL, NULL, 300 UMA_ALIGN_CACHE, 0); 301 kseinit(); /* set up kse specific stuff e.g. upcall zone*/ 302 } 303 304 /* 305 * Stash an embarasingly extra thread into the zombie thread queue. 306 */ 307 void 308 thread_stash(struct thread *td) 309 { 310 mtx_lock_spin(&kse_zombie_lock); 311 TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq); 312 mtx_unlock_spin(&kse_zombie_lock); 313 } 314 315 /* 316 * Stash an embarasingly extra ksegrp into the zombie ksegrp queue. 317 */ 318 void 319 ksegrp_stash(struct ksegrp *kg) 320 { 321 mtx_lock_spin(&kse_zombie_lock); 322 TAILQ_INSERT_HEAD(&zombie_ksegrps, kg, kg_ksegrp); 323 mtx_unlock_spin(&kse_zombie_lock); 324 } 325 326 /* 327 * Reap zombie kse resource. 328 */ 329 void 330 thread_reap(void) 331 { 332 struct thread *td_first, *td_next; 333 struct ksegrp *kg_first, * kg_next; 334 335 /* 336 * Don't even bother to lock if none at this instant, 337 * we really don't care about the next instant.. 338 */ 339 if ((!TAILQ_EMPTY(&zombie_threads)) 340 || (!TAILQ_EMPTY(&zombie_ksegrps))) { 341 mtx_lock_spin(&kse_zombie_lock); 342 td_first = TAILQ_FIRST(&zombie_threads); 343 kg_first = TAILQ_FIRST(&zombie_ksegrps); 344 if (td_first) 345 TAILQ_INIT(&zombie_threads); 346 if (kg_first) 347 TAILQ_INIT(&zombie_ksegrps); 348 mtx_unlock_spin(&kse_zombie_lock); 349 while (td_first) { 350 td_next = TAILQ_NEXT(td_first, td_runq); 351 if (td_first->td_ucred) 352 crfree(td_first->td_ucred); 353 thread_free(td_first); 354 td_first = td_next; 355 } 356 while (kg_first) { 357 kg_next = TAILQ_NEXT(kg_first, kg_ksegrp); 358 ksegrp_free(kg_first); 359 kg_first = kg_next; 360 } 361 /* 362 * there will always be a thread on the list if one of these 363 * is there. 364 */ 365 kse_GC(); 366 } 367 } 368 369 /* 370 * Allocate a ksegrp. 371 */ 372 struct ksegrp * 373 ksegrp_alloc(void) 374 { 375 return (uma_zalloc(ksegrp_zone, M_WAITOK)); 376 } 377 378 /* 379 * Allocate a thread. 380 */ 381 struct thread * 382 thread_alloc(void) 383 { 384 thread_reap(); /* check if any zombies to get */ 385 return (uma_zalloc(thread_zone, M_WAITOK)); 386 } 387 388 /* 389 * Deallocate a ksegrp. 390 */ 391 void 392 ksegrp_free(struct ksegrp *td) 393 { 394 uma_zfree(ksegrp_zone, td); 395 } 396 397 /* 398 * Deallocate a thread. 399 */ 400 void 401 thread_free(struct thread *td) 402 { 403 404 cpu_thread_clean(td); 405 uma_zfree(thread_zone, td); 406 } 407 408 /* 409 * Discard the current thread and exit from its context. 410 * Always called with scheduler locked. 411 * 412 * Because we can't free a thread while we're operating under its context, 413 * push the current thread into our CPU's deadthread holder. This means 414 * we needn't worry about someone else grabbing our context before we 415 * do a cpu_throw(). This may not be needed now as we are under schedlock. 416 * Maybe we can just do a thread_stash() as thr_exit1 does. 417 */ 418 /* XXX 419 * libthr expects its thread exit to return for the last 420 * thread, meaning that the program is back to non-threaded 421 * mode I guess. Because we do this (cpu_throw) unconditionally 422 * here, they have their own version of it. (thr_exit1()) 423 * that doesn't do it all if this was the last thread. 424 * It is also called from thread_suspend_check(). 425 * Of course in the end, they end up coming here through exit1 426 * anyhow.. After fixing 'thr' to play by the rules we should be able 427 * to merge these two functions together. 428 * 429 * called from: 430 * exit1() 431 * kse_exit() 432 * thr_exit() 433 * thread_user_enter() 434 * thread_userret() 435 * thread_suspend_check() 436 */ 437 void 438 thread_exit(void) 439 { 440 struct thread *td; 441 struct proc *p; 442 struct ksegrp *kg; 443 444 td = curthread; 445 kg = td->td_ksegrp; 446 p = td->td_proc; 447 448 mtx_assert(&sched_lock, MA_OWNED); 449 mtx_assert(&Giant, MA_NOTOWNED); 450 PROC_LOCK_ASSERT(p, MA_OWNED); 451 KASSERT(p != NULL, ("thread exiting without a process")); 452 KASSERT(kg != NULL, ("thread exiting without a kse group")); 453 CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td, 454 (long)p->p_pid, p->p_comm); 455 456 if (td->td_standin != NULL) { 457 /* 458 * Note that we don't need to free the cred here as it 459 * is done in thread_reap(). 460 */ 461 thread_stash(td->td_standin); 462 td->td_standin = NULL; 463 } 464 465 /* 466 * drop FPU & debug register state storage, or any other 467 * architecture specific resources that 468 * would not be on a new untouched process. 469 */ 470 cpu_thread_exit(td); /* XXXSMP */ 471 472 /* 473 * The thread is exiting. scheduler can release its stuff 474 * and collect stats etc. 475 */ 476 sched_thread_exit(td); 477 478 /* 479 * The last thread is left attached to the process 480 * So that the whole bundle gets recycled. Skip 481 * all this stuff if we never had threads. 482 * EXIT clears all sign of other threads when 483 * it goes to single threading, so the last thread always 484 * takes the short path. 485 */ 486 if (p->p_flag & P_HADTHREADS) { 487 if (p->p_numthreads > 1) { 488 thread_unlink(td); 489 490 /* XXX first arg not used in 4BSD or ULE */ 491 sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); 492 493 /* 494 * as we are exiting there is room for another 495 * to be created. 496 */ 497 if (p->p_maxthrwaits) 498 wakeup(&p->p_numthreads); 499 500 /* 501 * The test below is NOT true if we are the 502 * sole exiting thread. P_STOPPED_SNGL is unset 503 * in exit1() after it is the only survivor. 504 */ 505 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 506 if (p->p_numthreads == p->p_suspcount) { 507 thread_unsuspend_one(p->p_singlethread); 508 } 509 } 510 511 /* 512 * Because each upcall structure has an owner thread, 513 * owner thread exits only when process is in exiting 514 * state, so upcall to userland is no longer needed, 515 * deleting upcall structure is safe here. 516 * So when all threads in a group is exited, all upcalls 517 * in the group should be automatically freed. 518 * XXXKSE This is a KSE thing and should be exported 519 * there somehow. 520 */ 521 upcall_remove(td); 522 523 /* 524 * If the thread we unlinked above was the last one, 525 * then this ksegrp should go away too. 526 */ 527 if (kg->kg_numthreads == 0) { 528 /* 529 * let the scheduler know about this in case 530 * it needs to recover stats or resources. 531 * Theoretically we could let 532 * sched_exit_ksegrp() do the equivalent of 533 * setting the concurrency to 0 534 * but don't do it yet to avoid changing 535 * the existing scheduler code until we 536 * are ready. 537 * We supply a random other ksegrp 538 * as the recipient of any built up 539 * cpu usage etc. (If the scheduler wants it). 540 * XXXKSE 541 * This is probably not fair so think of 542 * a better answer. 543 */ 544 sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), td); 545 sched_set_concurrency(kg, 0); /* XXX TEMP */ 546 ksegrp_unlink(kg); 547 ksegrp_stash(kg); 548 } 549 PROC_UNLOCK(p); 550 td->td_ksegrp = NULL; 551 PCPU_SET(deadthread, td); 552 } else { 553 /* 554 * The last thread is exiting.. but not through exit() 555 * what should we do? 556 * Theoretically this can't happen 557 * exit1() - clears threading flags before coming here 558 * kse_exit() - treats last thread specially 559 * thr_exit() - treats last thread specially 560 * thread_user_enter() - only if more exist 561 * thread_userret() - only if more exist 562 * thread_suspend_check() - only if more exist 563 */ 564 panic ("thread_exit: Last thread exiting on its own"); 565 } 566 } else { 567 /* 568 * non threaded process comes here. 569 * This includes an EX threaded process that is coming 570 * here via exit1(). (exit1 dethreads the proc first). 571 */ 572 PROC_UNLOCK(p); 573 } 574 td->td_state = TDS_INACTIVE; 575 CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td); 576 cpu_throw(td, choosethread()); 577 panic("I'm a teapot!"); 578 /* NOTREACHED */ 579 } 580 581 /* 582 * Do any thread specific cleanups that may be needed in wait() 583 * called with Giant, proc and schedlock not held. 584 */ 585 void 586 thread_wait(struct proc *p) 587 { 588 struct thread *td; 589 590 mtx_assert(&Giant, MA_NOTOWNED); 591 KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); 592 KASSERT((p->p_numksegrps == 1), ("Multiple ksegrps in wait1()")); 593 FOREACH_THREAD_IN_PROC(p, td) { 594 if (td->td_standin != NULL) { 595 if (td->td_standin->td_ucred != NULL) { 596 crfree(td->td_standin->td_ucred); 597 td->td_standin->td_ucred = NULL; 598 } 599 thread_free(td->td_standin); 600 td->td_standin = NULL; 601 } 602 cpu_thread_clean(td); 603 crfree(td->td_ucred); 604 } 605 thread_reap(); /* check for zombie threads etc. */ 606 } 607 608 /* 609 * Link a thread to a process. 610 * set up anything that needs to be initialized for it to 611 * be used by the process. 612 * 613 * Note that we do not link to the proc's ucred here. 614 * The thread is linked as if running but no KSE assigned. 615 * Called from: 616 * proc_linkup() 617 * thread_schedule_upcall() 618 * thr_create() 619 */ 620 void 621 thread_link(struct thread *td, struct ksegrp *kg) 622 { 623 struct proc *p; 624 625 p = kg->kg_proc; 626 td->td_state = TDS_INACTIVE; 627 td->td_proc = p; 628 td->td_ksegrp = kg; 629 td->td_flags = 0; 630 td->td_kflags = 0; 631 632 LIST_INIT(&td->td_contested); 633 callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); 634 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 635 TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist); 636 p->p_numthreads++; 637 kg->kg_numthreads++; 638 } 639 640 /* 641 * Convert a process with one thread to an unthreaded process. 642 * Called from: 643 * thread_single(exit) (called from execve and exit) 644 * kse_exit() XXX may need cleaning up wrt KSE stuff 645 */ 646 void 647 thread_unthread(struct thread *td) 648 { 649 struct proc *p = td->td_proc; 650 651 KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads")); 652 upcall_remove(td); 653 p->p_flag &= ~(P_SA|P_HADTHREADS); 654 td->td_mailbox = NULL; 655 td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND); 656 if (td->td_standin != NULL) { 657 thread_stash(td->td_standin); 658 td->td_standin = NULL; 659 } 660 sched_set_concurrency(td->td_ksegrp, 1); 661 } 662 663 /* 664 * Called from: 665 * thread_exit() 666 */ 667 void 668 thread_unlink(struct thread *td) 669 { 670 struct proc *p = td->td_proc; 671 struct ksegrp *kg = td->td_ksegrp; 672 673 mtx_assert(&sched_lock, MA_OWNED); 674 TAILQ_REMOVE(&p->p_threads, td, td_plist); 675 p->p_numthreads--; 676 TAILQ_REMOVE(&kg->kg_threads, td, td_kglist); 677 kg->kg_numthreads--; 678 /* could clear a few other things here */ 679 /* Must NOT clear links to proc and ksegrp! */ 680 } 681 682 /* 683 * Enforce single-threading. 684 * 685 * Returns 1 if the caller must abort (another thread is waiting to 686 * exit the process or similar). Process is locked! 687 * Returns 0 when you are successfully the only thread running. 688 * A process has successfully single threaded in the suspend mode when 689 * There are no threads in user mode. Threads in the kernel must be 690 * allowed to continue until they get to the user boundary. They may even 691 * copy out their return values and data before suspending. They may however be 692 * accellerated in reaching the user boundary as we will wake up 693 * any sleeping threads that are interruptable. (PCATCH). 694 */ 695 int 696 thread_single(int mode) 697 { 698 struct thread *td; 699 struct thread *td2; 700 struct proc *p; 701 int remaining; 702 703 td = curthread; 704 p = td->td_proc; 705 mtx_assert(&Giant, MA_NOTOWNED); 706 PROC_LOCK_ASSERT(p, MA_OWNED); 707 KASSERT((td != NULL), ("curthread is NULL")); 708 709 if ((p->p_flag & P_HADTHREADS) == 0) 710 return (0); 711 712 /* Is someone already single threading? */ 713 if (p->p_singlethread != NULL && p->p_singlethread != td) 714 return (1); 715 716 if (mode == SINGLE_EXIT) { 717 p->p_flag |= P_SINGLE_EXIT; 718 p->p_flag &= ~P_SINGLE_BOUNDARY; 719 } else { 720 p->p_flag &= ~P_SINGLE_EXIT; 721 if (mode == SINGLE_BOUNDARY) 722 p->p_flag |= P_SINGLE_BOUNDARY; 723 else 724 p->p_flag &= ~P_SINGLE_BOUNDARY; 725 } 726 p->p_flag |= P_STOPPED_SINGLE; 727 mtx_lock_spin(&sched_lock); 728 p->p_singlethread = td; 729 if (mode == SINGLE_EXIT) 730 remaining = p->p_numthreads; 731 else if (mode == SINGLE_BOUNDARY) 732 remaining = p->p_numthreads - p->p_boundary_count; 733 else 734 remaining = p->p_numthreads - p->p_suspcount; 735 while (remaining != 1) { 736 FOREACH_THREAD_IN_PROC(p, td2) { 737 if (td2 == td) 738 continue; 739 td2->td_flags |= TDF_ASTPENDING; 740 if (TD_IS_INHIBITED(td2)) { 741 switch (mode) { 742 case SINGLE_EXIT: 743 if (td->td_flags & TDF_DBSUSPEND) 744 td->td_flags &= ~TDF_DBSUSPEND; 745 if (TD_IS_SUSPENDED(td2)) 746 thread_unsuspend_one(td2); 747 if (TD_ON_SLEEPQ(td2) && 748 (td2->td_flags & TDF_SINTR)) 749 sleepq_abort(td2); 750 break; 751 case SINGLE_BOUNDARY: 752 if (TD_IS_SUSPENDED(td2) && 753 !(td2->td_flags & TDF_BOUNDARY)) 754 thread_unsuspend_one(td2); 755 if (TD_ON_SLEEPQ(td2) && 756 (td2->td_flags & TDF_SINTR)) 757 sleepq_abort(td2); 758 break; 759 default: 760 if (TD_IS_SUSPENDED(td2)) 761 continue; 762 /* 763 * maybe other inhibitted states too? 764 */ 765 if ((td2->td_flags & TDF_SINTR) && 766 (td2->td_inhibitors & 767 (TDI_SLEEPING | TDI_SWAPPED))) 768 thread_suspend_one(td2); 769 break; 770 } 771 } 772 } 773 if (mode == SINGLE_EXIT) 774 remaining = p->p_numthreads; 775 else if (mode == SINGLE_BOUNDARY) 776 remaining = p->p_numthreads - p->p_boundary_count; 777 else 778 remaining = p->p_numthreads - p->p_suspcount; 779 780 /* 781 * Maybe we suspended some threads.. was it enough? 782 */ 783 if (remaining == 1) 784 break; 785 786 /* 787 * Wake us up when everyone else has suspended. 788 * In the mean time we suspend as well. 789 */ 790 thread_suspend_one(td); 791 PROC_UNLOCK(p); 792 mi_switch(SW_VOL, NULL); 793 mtx_unlock_spin(&sched_lock); 794 PROC_LOCK(p); 795 mtx_lock_spin(&sched_lock); 796 if (mode == SINGLE_EXIT) 797 remaining = p->p_numthreads; 798 else if (mode == SINGLE_BOUNDARY) 799 remaining = p->p_numthreads - p->p_boundary_count; 800 else 801 remaining = p->p_numthreads - p->p_suspcount; 802 } 803 if (mode == SINGLE_EXIT) { 804 /* 805 * We have gotten rid of all the other threads and we 806 * are about to either exit or exec. In either case, 807 * we try our utmost to revert to being a non-threaded 808 * process. 809 */ 810 p->p_singlethread = NULL; 811 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT); 812 thread_unthread(td); 813 } 814 mtx_unlock_spin(&sched_lock); 815 return (0); 816 } 817 818 /* 819 * Called in from locations that can safely check to see 820 * whether we have to suspend or at least throttle for a 821 * single-thread event (e.g. fork). 822 * 823 * Such locations include userret(). 824 * If the "return_instead" argument is non zero, the thread must be able to 825 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 826 * 827 * The 'return_instead' argument tells the function if it may do a 828 * thread_exit() or suspend, or whether the caller must abort and back 829 * out instead. 830 * 831 * If the thread that set the single_threading request has set the 832 * P_SINGLE_EXIT bit in the process flags then this call will never return 833 * if 'return_instead' is false, but will exit. 834 * 835 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 836 *---------------+--------------------+--------------------- 837 * 0 | returns 0 | returns 0 or 1 838 * | when ST ends | immediatly 839 *---------------+--------------------+--------------------- 840 * 1 | thread exits | returns 1 841 * | | immediatly 842 * 0 = thread_exit() or suspension ok, 843 * other = return error instead of stopping the thread. 844 * 845 * While a full suspension is under effect, even a single threading 846 * thread would be suspended if it made this call (but it shouldn't). 847 * This call should only be made from places where 848 * thread_exit() would be safe as that may be the outcome unless 849 * return_instead is set. 850 */ 851 int 852 thread_suspend_check(int return_instead) 853 { 854 struct thread *td; 855 struct proc *p; 856 857 td = curthread; 858 p = td->td_proc; 859 mtx_assert(&Giant, MA_NOTOWNED); 860 PROC_LOCK_ASSERT(p, MA_OWNED); 861 while (P_SHOULDSTOP(p) || 862 ((p->p_flag & P_TRACED) && (td->td_flags & TDF_DBSUSPEND))) { 863 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 864 KASSERT(p->p_singlethread != NULL, 865 ("singlethread not set")); 866 /* 867 * The only suspension in action is a 868 * single-threading. Single threader need not stop. 869 * XXX Should be safe to access unlocked 870 * as it can only be set to be true by us. 871 */ 872 if (p->p_singlethread == td) 873 return (0); /* Exempt from stopping. */ 874 } 875 if ((p->p_flag & P_SINGLE_EXIT) && return_instead) 876 return (1); 877 878 /* Should we goto user boundary if we didn't come from there? */ 879 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE && 880 (p->p_flag & P_SINGLE_BOUNDARY) && return_instead) 881 return (1); 882 883 mtx_lock_spin(&sched_lock); 884 thread_stopped(p); 885 /* 886 * If the process is waiting for us to exit, 887 * this thread should just suicide. 888 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. 889 */ 890 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) 891 thread_exit(); 892 893 /* 894 * When a thread suspends, it just 895 * moves to the processes's suspend queue 896 * and stays there. 897 */ 898 thread_suspend_one(td); 899 if (return_instead == 0) { 900 p->p_boundary_count++; 901 td->td_flags |= TDF_BOUNDARY; 902 } 903 if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { 904 if (p->p_numthreads == p->p_suspcount) 905 thread_unsuspend_one(p->p_singlethread); 906 } 907 PROC_UNLOCK(p); 908 mi_switch(SW_INVOL, NULL); 909 if (return_instead == 0) { 910 p->p_boundary_count--; 911 td->td_flags &= ~TDF_BOUNDARY; 912 } 913 mtx_unlock_spin(&sched_lock); 914 PROC_LOCK(p); 915 } 916 return (0); 917 } 918 919 void 920 thread_suspend_one(struct thread *td) 921 { 922 struct proc *p = td->td_proc; 923 924 mtx_assert(&sched_lock, MA_OWNED); 925 PROC_LOCK_ASSERT(p, MA_OWNED); 926 KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 927 p->p_suspcount++; 928 TD_SET_SUSPENDED(td); 929 TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq); 930 /* 931 * Hack: If we are suspending but are on the sleep queue 932 * then we are in msleep or the cv equivalent. We 933 * want to look like we have two Inhibitors. 934 * May already be set.. doesn't matter. 935 */ 936 if (TD_ON_SLEEPQ(td)) 937 TD_SET_SLEEPING(td); 938 } 939 940 void 941 thread_unsuspend_one(struct thread *td) 942 { 943 struct proc *p = td->td_proc; 944 945 mtx_assert(&sched_lock, MA_OWNED); 946 PROC_LOCK_ASSERT(p, MA_OWNED); 947 TAILQ_REMOVE(&p->p_suspended, td, td_runq); 948 TD_CLR_SUSPENDED(td); 949 p->p_suspcount--; 950 setrunnable(td); 951 } 952 953 /* 954 * Allow all threads blocked by single threading to continue running. 955 */ 956 void 957 thread_unsuspend(struct proc *p) 958 { 959 struct thread *td; 960 961 mtx_assert(&sched_lock, MA_OWNED); 962 PROC_LOCK_ASSERT(p, MA_OWNED); 963 if (!P_SHOULDSTOP(p)) { 964 while ((td = TAILQ_FIRST(&p->p_suspended))) { 965 thread_unsuspend_one(td); 966 } 967 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && 968 (p->p_numthreads == p->p_suspcount)) { 969 /* 970 * Stopping everything also did the job for the single 971 * threading request. Now we've downgraded to single-threaded, 972 * let it continue. 973 */ 974 thread_unsuspend_one(p->p_singlethread); 975 } 976 } 977 978 /* 979 * End the single threading mode.. 980 */ 981 void 982 thread_single_end(void) 983 { 984 struct thread *td; 985 struct proc *p; 986 987 td = curthread; 988 p = td->td_proc; 989 PROC_LOCK_ASSERT(p, MA_OWNED); 990 p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT | P_SINGLE_BOUNDARY); 991 mtx_lock_spin(&sched_lock); 992 p->p_singlethread = NULL; 993 /* 994 * If there are other threads they mey now run, 995 * unless of course there is a blanket 'stop order' 996 * on the process. The single threader must be allowed 997 * to continue however as this is a bad place to stop. 998 */ 999 if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { 1000 while ((td = TAILQ_FIRST(&p->p_suspended))) { 1001 thread_unsuspend_one(td); 1002 } 1003 } 1004 mtx_unlock_spin(&sched_lock); 1005 } 1006 1007 /* 1008 * Called before going into an interruptible sleep to see if we have been 1009 * interrupted or requested to exit. 1010 */ 1011 int 1012 thread_sleep_check(struct thread *td) 1013 { 1014 struct proc *p; 1015 1016 p = td->td_proc; 1017 mtx_assert(&sched_lock, MA_OWNED); 1018 if (p->p_flag & P_HADTHREADS) { 1019 if (p->p_singlethread != td) { 1020 if (p->p_flag & P_SINGLE_EXIT) 1021 return (EINTR); 1022 if (p->p_flag & P_SINGLE_BOUNDARY) 1023 return (ERESTART); 1024 } 1025 if (td->td_flags & TDF_INTERRUPT) 1026 return (td->td_intrval); 1027 } 1028 return (0); 1029 } 1030