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 * $FreeBSD$ 29 */ 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/kernel.h> 34 #include <sys/lock.h> 35 #include <sys/malloc.h> 36 #include <sys/mutex.h> 37 #include <sys/proc.h> 38 #include <sys/sysctl.h> 39 #include <sys/filedesc.h> 40 #include <sys/tty.h> 41 #include <sys/signalvar.h> 42 #include <sys/sx.h> 43 #include <sys/user.h> 44 #include <sys/jail.h> 45 #include <sys/kse.h> 46 #include <sys/ktr.h> 47 48 #include <vm/vm.h> 49 #include <vm/vm_object.h> 50 #include <vm/pmap.h> 51 #include <vm/uma.h> 52 #include <vm/vm_map.h> 53 54 #include <machine/frame.h> 55 56 /* 57 * Thread related storage. 58 */ 59 static uma_zone_t thread_zone; 60 static int allocated_threads; 61 static int active_threads; 62 static int cached_threads; 63 64 SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation"); 65 66 SYSCTL_INT(_kern_threads, OID_AUTO, active, CTLFLAG_RD, 67 &active_threads, 0, "Number of active threads in system."); 68 69 SYSCTL_INT(_kern_threads, OID_AUTO, cached, CTLFLAG_RD, 70 &cached_threads, 0, "Number of threads in thread cache."); 71 72 SYSCTL_INT(_kern_threads, OID_AUTO, allocated, CTLFLAG_RD, 73 &allocated_threads, 0, "Number of threads in zone."); 74 75 static int oiks_debug = 1; /* 0 disable, 1 printf, 2 enter debugger */ 76 SYSCTL_INT(_kern_threads, OID_AUTO, oiks, CTLFLAG_RW, 77 &oiks_debug, 0, "OIKS thread debug"); 78 79 #define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start)) 80 81 struct threadqueue zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); 82 struct mtx zombie_thread_lock; 83 MTX_SYSINIT(zombie_thread_lock, &zombie_thread_lock, 84 "zombie_thread_lock", MTX_SPIN); 85 86 /* 87 * Pepare a thread for use. 88 */ 89 static void 90 thread_ctor(void *mem, int size, void *arg) 91 { 92 struct thread *td; 93 94 KASSERT((size == sizeof(struct thread)), 95 ("size mismatch: %d != %d\n", size, (int)sizeof(struct thread))); 96 97 td = (struct thread *)mem; 98 bzero(&td->td_startzero, 99 (unsigned)RANGEOF(struct thread, td_startzero, td_endzero)); 100 td->td_state = TDS_NEW; 101 td->td_flags |= TDF_UNBOUND; 102 #if 0 103 /* 104 * Maybe move these here from process creation, but maybe not. 105 * Moving them here takes them away from their "natural" place 106 * in the fork process. 107 */ 108 /* XXX td_contested does not appear to be initialized for threads! */ 109 LIST_INIT(&td->td_contested); 110 callout_init(&td->td_slpcallout, 1); 111 #endif 112 cached_threads--; /* XXXSMP */ 113 active_threads++; /* XXXSMP */ 114 } 115 116 /* 117 * Reclaim a thread after use. 118 */ 119 static void 120 thread_dtor(void *mem, int size, void *arg) 121 { 122 struct thread *td; 123 124 KASSERT((size == sizeof(struct thread)), 125 ("size mismatch: %d != %d\n", size, (int)sizeof(struct thread))); 126 127 td = (struct thread *)mem; 128 129 #ifdef INVARIANTS 130 /* Verify that this thread is in a safe state to free. */ 131 switch (td->td_state) { 132 case TDS_SLP: 133 case TDS_MTX: 134 case TDS_RUNQ: 135 /* 136 * We must never unlink a thread that is in one of 137 * these states, because it is currently active. 138 */ 139 panic("bad state for thread unlinking"); 140 /* NOTREACHED */ 141 case TDS_UNQUEUED: 142 case TDS_NEW: 143 case TDS_RUNNING: 144 case TDS_SURPLUS: 145 break; 146 default: 147 panic("bad thread state"); 148 /* NOTREACHED */ 149 } 150 #endif 151 152 /* Update counters. */ 153 active_threads--; /* XXXSMP */ 154 cached_threads++; /* XXXSMP */ 155 } 156 157 /* 158 * Initialize type-stable parts of a thread (when newly created). 159 */ 160 static void 161 thread_init(void *mem, int size) 162 { 163 struct thread *td; 164 165 KASSERT((size == sizeof(struct thread)), 166 ("size mismatch: %d != %d\n", size, (int)sizeof(struct thread))); 167 168 td = (struct thread *)mem; 169 pmap_new_thread(td); 170 cpu_thread_setup(td); 171 cached_threads++; /* XXXSMP */ 172 allocated_threads++; /* XXXSMP */ 173 } 174 175 /* 176 * Tear down type-stable parts of a thread (just before being discarded). 177 */ 178 static void 179 thread_fini(void *mem, int size) 180 { 181 struct thread *td; 182 183 KASSERT((size == sizeof(struct thread)), 184 ("size mismatch: %d != %d\n", size, (int)sizeof(struct thread))); 185 186 td = (struct thread *)mem; 187 pmap_dispose_thread(td); 188 cached_threads--; /* XXXSMP */ 189 allocated_threads--; /* XXXSMP */ 190 } 191 192 /* 193 * Initialize global thread allocation resources. 194 */ 195 void 196 threadinit(void) 197 { 198 199 thread_zone = uma_zcreate("THREAD", sizeof (struct thread), 200 thread_ctor, thread_dtor, thread_init, thread_fini, 201 UMA_ALIGN_CACHE, 0); 202 } 203 204 /* 205 * Stash an embarasingly esxtra thread into the zombie thread queue. 206 */ 207 void 208 thread_stash(struct thread *td) 209 { 210 mtx_lock_spin(&zombie_thread_lock); 211 TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq); 212 mtx_unlock_spin(&zombie_thread_lock); 213 } 214 215 /* 216 * reap any zombie threads. 217 */ 218 void 219 thread_reap(void) 220 { 221 struct thread *td_reaped; 222 223 /* 224 * don't even bother to lock if none at this instant 225 * We really don't care about the next instant.. 226 */ 227 if (!TAILQ_EMPTY(&zombie_threads)) { 228 mtx_lock_spin(&zombie_thread_lock); 229 while (!TAILQ_EMPTY(&zombie_threads)) { 230 td_reaped = TAILQ_FIRST(&zombie_threads); 231 TAILQ_REMOVE(&zombie_threads, td_reaped, td_runq); 232 mtx_unlock_spin(&zombie_thread_lock); 233 thread_free(td_reaped); 234 mtx_lock_spin(&zombie_thread_lock); 235 } 236 mtx_unlock_spin(&zombie_thread_lock); 237 } 238 } 239 240 /* 241 * Allocate a thread. 242 */ 243 struct thread * 244 thread_alloc(void) 245 { 246 thread_reap(); /* check if any zombies to get */ 247 return (uma_zalloc(thread_zone, M_WAITOK)); 248 } 249 250 /* 251 * Deallocate a thread. 252 */ 253 void 254 thread_free(struct thread *td) 255 { 256 uma_zfree(thread_zone, td); 257 } 258 259 /* 260 * Store the thread context in the UTS's mailbox. 261 */ 262 int 263 thread_export_context(struct thread *td) 264 { 265 struct kse *ke; 266 uintptr_t td2_mbx; 267 void *addr1; 268 void *addr2; 269 int error; 270 271 #ifdef __ia64__ 272 td2_mbx = 0; /* pacify gcc (!) */ 273 #endif 274 /* Export the register contents. */ 275 error = cpu_export_context(td); 276 277 ke = td->td_kse; 278 addr1 = (caddr_t)ke->ke_mailbox 279 + offsetof(struct kse_mailbox, kmbx_completed_threads); 280 addr2 = (caddr_t)td->td_mailbox 281 + offsetof(struct thread_mailbox , next_completed); 282 /* Then link it into it's KSE's list of completed threads. */ 283 if (!error) { 284 error = td2_mbx = fuword(addr1); 285 if (error == -1) 286 error = EFAULT; 287 else 288 error = 0; 289 } 290 if (!error) 291 error = suword(addr2, td2_mbx); 292 if (!error) 293 error = suword(addr1, (u_long)td->td_mailbox); 294 if (error == -1) 295 error = EFAULT; 296 return (error); 297 } 298 299 300 /* 301 * Discard the current thread and exit from its context. 302 * 303 * Because we can't free a thread while we're operating under its context, 304 * push the current thread into our KSE's ke_tdspare slot, freeing the 305 * thread that might be there currently. Because we know that only this 306 * processor will run our KSE, we needn't worry about someone else grabbing 307 * our context before we do a cpu_throw. 308 */ 309 void 310 thread_exit(void) 311 { 312 struct thread *td; 313 struct kse *ke; 314 struct proc *p; 315 struct ksegrp *kg; 316 317 td = curthread; 318 kg = td->td_ksegrp; 319 p = td->td_proc; 320 ke = td->td_kse; 321 322 mtx_assert(&sched_lock, MA_OWNED); 323 PROC_LOCK_ASSERT(p, MA_OWNED); 324 CTR1(KTR_PROC, "thread_exit: thread %p", td); 325 KASSERT(!mtx_owned(&Giant), ("dying thread owns giant")); 326 327 if (ke->ke_tdspare != NULL) { 328 thread_stash(ke->ke_tdspare); 329 ke->ke_tdspare = NULL; 330 } 331 cpu_thread_exit(td); /* XXXSMP */ 332 333 /* Reassign this thread's KSE. */ 334 if (ke != NULL) { 335 ke->ke_thread = NULL; 336 td->td_kse = NULL; 337 ke->ke_state = KES_UNQUEUED; 338 kse_reassign(ke); 339 } 340 341 /* Unlink this thread from its proc. and the kseg */ 342 if (p != NULL) { 343 TAILQ_REMOVE(&p->p_threads, td, td_plist); 344 p->p_numthreads--; 345 if (kg != NULL) { 346 TAILQ_REMOVE(&kg->kg_threads, td, td_kglist); 347 kg->kg_numthreads--; 348 } 349 /* 350 * The test below is NOT true if we are the 351 * sole exiting thread. P_STOPPED_SNGL is unset 352 * in exit1() after it is the only survivor. 353 */ 354 if (P_SHOULDSTOP(p) == P_STOPPED_SNGL) { 355 if (p->p_numthreads == p->p_suspcount) { 356 TAILQ_REMOVE(&p->p_suspended, 357 p->p_singlethread, td_runq); 358 setrunqueue(p->p_singlethread); 359 p->p_suspcount--; 360 } 361 } 362 } 363 td->td_state = TDS_SURPLUS; 364 td->td_proc = NULL; 365 td->td_ksegrp = NULL; 366 td->td_last_kse = NULL; 367 ke->ke_tdspare = td; 368 PROC_UNLOCK(p); 369 cpu_throw(); 370 /* NOTREACHED */ 371 } 372 373 /* 374 * Link a thread to a process. 375 * 376 * Note that we do not link to the proc's ucred here. 377 * The thread is linked as if running but no KSE assigned. 378 */ 379 void 380 thread_link(struct thread *td, struct ksegrp *kg) 381 { 382 struct proc *p; 383 384 p = kg->kg_proc; 385 td->td_state = TDS_NEW; 386 td->td_proc = p; 387 td->td_ksegrp = kg; 388 td->td_last_kse = NULL; 389 390 TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); 391 TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist); 392 p->p_numthreads++; 393 kg->kg_numthreads++; 394 if (oiks_debug && p->p_numthreads > 4) { 395 printf("OIKS %d\n", p->p_numthreads); 396 if (oiks_debug > 1) 397 Debugger("OIKS"); 398 } 399 td->td_critnest = 0; 400 td->td_kse = NULL; 401 } 402 403 /* 404 * Set up the upcall pcb in either a given thread or a new one 405 * if none given. Use the upcall for the given KSE 406 * XXXKSE possibly fix cpu_set_upcall() to not need td->td_kse set. 407 */ 408 struct thread * 409 thread_schedule_upcall(struct thread *td, struct kse *ke) 410 { 411 struct thread *td2; 412 413 mtx_assert(&sched_lock, MA_OWNED); 414 if (ke->ke_tdspare != NULL) { 415 td2 = ke->ke_tdspare; 416 ke->ke_tdspare = NULL; 417 } else { 418 mtx_unlock_spin(&sched_lock); 419 td2 = thread_alloc(); 420 mtx_lock_spin(&sched_lock); 421 } 422 CTR3(KTR_PROC, "thread_schedule_upcall: thread %p (pid %d, %s)", 423 td, td->td_proc->p_pid, td->td_proc->p_comm); 424 thread_link(td2, ke->ke_ksegrp); 425 cpu_set_upcall(td2, ke->ke_pcb); 426 td2->td_ucred = crhold(td->td_ucred); 427 td2->td_flags = TDF_UNBOUND|TDF_UPCALLING; 428 td2->td_priority = td->td_priority; 429 setrunqueue(td2); 430 return (td2); 431 } 432 433 /* 434 * The extra work we go through if we are a threaded process when we 435 * return to userland 436 * 437 * If we are a KSE process and returning to user mode, check for 438 * extra work to do before we return (e.g. for more syscalls 439 * to complete first). If we were in a critical section, we should 440 * just return to let it finish. Same if we were in the UTS (in 441 * which case we will have no thread mailbox registered). The only 442 * traps we suport will have set the mailbox. We will clear it here. 443 */ 444 int 445 thread_userret(struct proc *p, struct ksegrp *kg, struct kse *ke, 446 struct thread *td, struct trapframe *frame) 447 { 448 int error = 0; 449 450 if (ke->ke_tdspare == NULL) { 451 ke->ke_tdspare = thread_alloc(); 452 } 453 if (td->td_flags & TDF_UNBOUND) { 454 /* 455 * Are we returning from a thread that had a mailbox? 456 * 457 * XXX Maybe this should be in a separate function. 458 */ 459 if (((td->td_flags & TDF_UPCALLING) == 0) && td->td_mailbox) { 460 /* 461 * [XXXKSE Future enhancement] 462 * We could also go straight back to the syscall 463 * if we never had to do an upcall since then. 464 * If the KSE's copy is == the thread's copy.. 465 * AND there are no other completed threads. 466 */ 467 /* 468 * We will go back as an upcall or go do another thread. 469 * Either way we need to save the context back to 470 * the user thread mailbox. 471 * So the UTS can restart it later. 472 */ 473 error = thread_export_context(td); 474 td->td_mailbox = NULL; 475 if (error) { 476 /* 477 * Failing to do the KSE 478 * operation just defaults operation 479 * back to synchonous operation. 480 */ 481 goto cont; 482 } 483 484 if (TAILQ_FIRST(&kg->kg_runq)) { 485 /* 486 * Uh-oh.. don't return to the user. 487 * Instead, switch to the thread that 488 * needs to run. The question is: 489 * What do we do with the thread we have now? 490 * We have put the completion block 491 * on the kse mailbox. If we had more energy, 492 * we could lazily do so, assuming someone 493 * else might get to userland earlier 494 * and deliver it earlier than we could. 495 * To do that we could save it off the KSEG. 496 * An upcalling KSE would 'reap' all completed 497 * threads. 498 * Being in a hurry, we'll do nothing and 499 * leave it on the current KSE for now. 500 * 501 * As for the other threads to run; 502 * we COULD rush through all the threads 503 * in this KSEG at this priority, or we 504 * could throw the ball back into the court 505 * and just run the highest prio kse available. 506 * What is OUR priority? 507 * the priority of the highest sycall waiting 508 * to be returned? 509 * For now, just let another KSE run (easiest). 510 */ 511 PROC_LOCK(p); 512 mtx_lock_spin(&sched_lock); 513 thread_exit(); /* Abandon current thread. */ 514 /* NOTREACHED */ 515 } else { /* if (number of returning syscalls = 1) */ 516 /* 517 * Swap our frame for the upcall frame. 518 * 519 * XXXKSE Assumes we are going to user land 520 * and not nested in the kernel 521 */ 522 td->td_flags |= TDF_UPCALLING; 523 } 524 } 525 /* 526 * This is NOT just an 'else' clause for the above test... 527 */ 528 if (td->td_flags & TDF_UPCALLING) { 529 CTR3(KTR_PROC, "userret: upcall thread %p (pid %d, %s)", 530 td, p->p_pid, p->p_comm); 531 /* 532 * Make sure that it has the correct frame loaded. 533 * While we know that we are on the same KSEGRP 534 * as we were created on, we could very easily 535 * have come in on another KSE. We therefore need 536 * to do the copy of the frame after the last 537 * possible switch() (the one above). 538 */ 539 bcopy(ke->ke_frame, frame, sizeof(struct trapframe)); 540 541 /* 542 * Decide what we are sending to the user 543 * upcall sets one argument. The address of the mbox. 544 */ 545 cpu_set_args(td, ke); 546 547 /* 548 * There is no more work to do and we are going to ride 549 * this thead/KSE up to userland. Make sure the user's 550 * pointer to the thread mailbox is cleared before we 551 * re-enter the kernel next time for any reason.. 552 * We might as well do it here. 553 */ 554 td->td_flags &= ~TDF_UPCALLING; /* Hmmmm. */ 555 error = suword((caddr_t)td->td_kse->ke_mailbox + 556 offsetof(struct kse_mailbox, kmbx_current_thread), 557 0); 558 } 559 /* 560 * Stop any chance that we may be separated from 561 * the KSE we are currently on. This is "biting the bullet", 562 * we are committing to go to user space as as THIS KSE here. 563 */ 564 cont: 565 td->td_flags &= ~TDF_UNBOUND; 566 } 567 return (error); 568 } 569 570 /* 571 * Enforce single-threading. 572 * 573 * Returns 1 if the caller must abort (another thread is waiting to 574 * exit the process or similar). Process is locked! 575 * Returns 0 when you are successfully the only thread running. 576 * A process has successfully single threaded in the suspend mode when 577 * There are no threads in user mode. Threads in the kernel must be 578 * allowed to continue until they get to the user boundary. They may even 579 * copy out their return values and data before suspending. They may however be 580 * accellerated in reaching the user boundary as we will wake up 581 * any sleeping threads that are interruptable. (PCATCH). 582 */ 583 int 584 thread_single(int force_exit) 585 { 586 struct thread *td; 587 struct thread *td2; 588 struct proc *p; 589 590 td = curthread; 591 p = td->td_proc; 592 PROC_LOCK_ASSERT(p, MA_OWNED); 593 KASSERT((td != NULL), ("curthread is NULL")); 594 595 if ((p->p_flag & P_KSES) == 0) 596 return (0); 597 598 /* Is someone already single threading? */ 599 if (p->p_singlethread) 600 return (1); 601 602 if (force_exit == SNGLE_EXIT) 603 p->p_flag |= P_SINGLE_EXIT; 604 else 605 p->p_flag &= ~P_SINGLE_EXIT; 606 p->p_flag |= P_STOPPED_SNGL; 607 p->p_singlethread = td; 608 while ((p->p_numthreads - p->p_suspcount) != 1) { 609 FOREACH_THREAD_IN_PROC(p, td2) { 610 if (td2 == td) 611 continue; 612 switch(td2->td_state) { 613 case TDS_SUSPENDED: 614 if (force_exit == SNGLE_EXIT) { 615 mtx_lock_spin(&sched_lock); 616 TAILQ_REMOVE(&p->p_suspended, 617 td, td_runq); 618 p->p_suspcount--; 619 setrunqueue(td); /* Should suicide. */ 620 mtx_unlock_spin(&sched_lock); 621 } 622 case TDS_SLP: 623 if (td2->td_flags & TDF_CVWAITQ) 624 cv_abort(td2); 625 else 626 abortsleep(td2); 627 break; 628 /* case TDS RUNNABLE: XXXKSE maybe raise priority? */ 629 default: /* needed to avoid an error */ 630 break; 631 } 632 } 633 /* 634 * Wake us up when everyone else has suspended. 635 * In the mean time we suspend as well. 636 */ 637 mtx_lock_spin(&sched_lock); 638 TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq); 639 td->td_state = TDS_SUSPENDED; 640 p->p_suspcount++; 641 mtx_unlock(&Giant); 642 PROC_UNLOCK(p); 643 mi_switch(); 644 mtx_unlock_spin(&sched_lock); 645 mtx_lock(&Giant); 646 PROC_LOCK(p); 647 } 648 return (0); 649 } 650 651 /* 652 * Called in from locations that can safely check to see 653 * whether we have to suspend or at least throttle for a 654 * single-thread event (e.g. fork). 655 * 656 * Such locations include userret(). 657 * If the "return_instead" argument is non zero, the thread must be able to 658 * accept 0 (caller may continue), or 1 (caller must abort) as a result. 659 * 660 * The 'return_instead' argument tells the function if it may do a 661 * thread_exit() or suspend, or whether the caller must abort and back 662 * out instead. 663 * 664 * If the thread that set the single_threading request has set the 665 * P_SINGLE_EXIT bit in the process flags then this call will never return 666 * if 'return_instead' is false, but will exit. 667 * 668 * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 669 *---------------+--------------------+--------------------- 670 * 0 | returns 0 | returns 0 or 1 671 * | when ST ends | immediatly 672 *---------------+--------------------+--------------------- 673 * 1 | thread exits | returns 1 674 * | | immediatly 675 * 0 = thread_exit() or suspension ok, 676 * other = return error instead of stopping the thread. 677 * 678 * While a full suspension is under effect, even a single threading 679 * thread would be suspended if it made this call (but it shouldn't). 680 * This call should only be made from places where 681 * thread_exit() would be safe as that may be the outcome unless 682 * return_instead is set. 683 */ 684 int 685 thread_suspend_check(int return_instead) 686 { 687 struct thread *td = curthread; 688 struct proc *p = td->td_proc; 689 690 td = curthread; 691 p = td->td_proc; 692 PROC_LOCK_ASSERT(p, MA_OWNED); 693 while (P_SHOULDSTOP(p)) { 694 if (P_SHOULDSTOP(p) == P_STOPPED_SNGL) { 695 KASSERT(p->p_singlethread != NULL, 696 ("singlethread not set")); 697 /* 698 * The only suspension in action is a 699 * single-threading. Single threader need not stop. 700 * XXX Should be safe to access unlocked 701 * as it can only be set to be true by us. 702 */ 703 if (p->p_singlethread == td) 704 return (0); /* Exempt from stopping. */ 705 } 706 if (return_instead) 707 return (1); 708 709 /* 710 * If the process is waiting for us to exit, 711 * this thread should just suicide. 712 * Assumes that P_SINGLE_EXIT implies P_STOPPED_SNGL. 713 */ 714 if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { 715 mtx_lock_spin(&sched_lock); 716 while (mtx_owned(&Giant)) 717 mtx_unlock(&Giant); 718 thread_exit(); 719 } 720 721 /* 722 * When a thread suspends, it just 723 * moves to the processes's suspend queue 724 * and stays there. 725 * 726 * XXXKSE if TDF_BOUND is true 727 * it will not release it's KSE which might 728 * lead to deadlock if there are not enough KSEs 729 * to complete all waiting threads. 730 * Maybe be able to 'lend' it out again. 731 * (lent kse's can not go back to userland?) 732 * and can only be lent in STOPPED state. 733 */ 734 mtx_lock_spin(&sched_lock); 735 if ((p->p_flag & P_STOPPED_SGNL) && 736 (p->p_suspcount+1 == p->p_numthreads)) { 737 mtx_unlock_spin(&sched_lock); 738 PROC_LOCK(p->p_pptr); 739 if ((p->p_pptr->p_procsig->ps_flag & 740 PS_NOCLDSTOP) == 0) { 741 psignal(p->p_pptr, SIGCHLD); 742 } 743 PROC_UNLOCK(p->p_pptr); 744 } 745 mtx_assert(&Giant, MA_NOTOWNED); 746 mtx_lock_spin(&sched_lock); 747 p->p_suspcount++; 748 td->td_state = TDS_SUSPENDED; 749 TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq); 750 PROC_UNLOCK(p); 751 if (P_SHOULDSTOP(p) == P_STOPPED_SNGL) { 752 if (p->p_numthreads == p->p_suspcount) { 753 TAILQ_REMOVE(&p->p_suspended, 754 p->p_singlethread, td_runq); 755 p->p_suspcount--; 756 setrunqueue(p->p_singlethread); 757 } 758 } 759 p->p_stats->p_ru.ru_nivcsw++; 760 mi_switch(); 761 mtx_unlock_spin(&sched_lock); 762 PROC_LOCK(p); 763 } 764 return (0); 765 } 766 767 /* 768 * Allow all threads blocked by single threading to continue running. 769 */ 770 void 771 thread_unsuspend(struct proc *p) 772 { 773 struct thread *td; 774 775 mtx_assert(&sched_lock, MA_OWNED); 776 PROC_LOCK_ASSERT(p, MA_OWNED); 777 if (!P_SHOULDSTOP(p)) { 778 while (( td = TAILQ_FIRST(&p->p_suspended))) { 779 TAILQ_REMOVE(&p->p_suspended, td, td_runq); 780 p->p_suspcount--; 781 setrunqueue(td); 782 } 783 } else if ((P_SHOULDSTOP(p) == P_STOPPED_SNGL) && 784 (p->p_numthreads == p->p_suspcount)) { 785 /* 786 * Stopping everything also did the job for the single 787 * threading request. Now we've downgraded to single-threaded, 788 * let it continue. 789 */ 790 TAILQ_REMOVE(&p->p_suspended, p->p_singlethread, td_runq); 791 p->p_suspcount--; 792 setrunqueue(p->p_singlethread); 793 } 794 } 795 796 void 797 thread_single_end(void) 798 { 799 struct thread *td; 800 struct proc *p; 801 802 td = curthread; 803 p = td->td_proc; 804 PROC_LOCK_ASSERT(p, MA_OWNED); 805 p->p_flag &= ~P_STOPPED_SNGL; 806 p->p_singlethread = NULL; 807 thread_unsuspend(p); 808 } 809 810