1 /* 2 * Copyright (c) 1982, 1986, 1989, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94 39 * $FreeBSD: src/sys/kern/kern_exit.c,v 1.92.2.11 2003/01/13 22:51:16 dillon Exp $ 40 * $DragonFly: src/sys/kern/kern_exit.c,v 1.91 2008/05/18 20:02:02 nth Exp $ 41 */ 42 43 #include "opt_compat.h" 44 #include "opt_ktrace.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/sysproto.h> 49 #include <sys/kernel.h> 50 #include <sys/malloc.h> 51 #include <sys/proc.h> 52 #include <sys/ktrace.h> 53 #include <sys/pioctl.h> 54 #include <sys/tty.h> 55 #include <sys/wait.h> 56 #include <sys/vnode.h> 57 #include <sys/resourcevar.h> 58 #include <sys/signalvar.h> 59 #include <sys/taskqueue.h> 60 #include <sys/ptrace.h> 61 #include <sys/acct.h> /* for acct_process() function prototype */ 62 #include <sys/filedesc.h> 63 #include <sys/shm.h> 64 #include <sys/sem.h> 65 #include <sys/aio.h> 66 #include <sys/jail.h> 67 #include <sys/kern_syscall.h> 68 #include <sys/upcall.h> 69 #include <sys/caps.h> 70 #include <sys/unistd.h> 71 #include <sys/eventhandler.h> 72 73 #include <vm/vm.h> 74 #include <vm/vm_param.h> 75 #include <sys/lock.h> 76 #include <vm/pmap.h> 77 #include <vm/vm_map.h> 78 #include <vm/vm_extern.h> 79 #include <sys/user.h> 80 81 #include <sys/thread2.h> 82 #include <sys/sysref2.h> 83 #include <sys/mplock2.h> 84 85 static void reaplwps(void *context, int dummy); 86 static void reaplwp(struct lwp *lp); 87 static void killlwps(struct lwp *lp); 88 89 static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback"); 90 static MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status"); 91 92 /* 93 * callout list for things to do at exit time 94 */ 95 struct exitlist { 96 exitlist_fn function; 97 TAILQ_ENTRY(exitlist) next; 98 }; 99 100 TAILQ_HEAD(exit_list_head, exitlist); 101 static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list); 102 103 /* 104 * LWP reaper data 105 */ 106 struct task *deadlwp_task[MAXCPU]; 107 struct lwplist deadlwp_list[MAXCPU]; 108 109 /* 110 * exit -- 111 * Death of process. 112 * 113 * SYS_EXIT_ARGS(int rval) 114 * 115 * MPALMOSTSAFE 116 */ 117 int 118 sys_exit(struct exit_args *uap) 119 { 120 get_mplock(); 121 exit1(W_EXITCODE(uap->rval, 0)); 122 /* NOTREACHED */ 123 rel_mplock(); 124 } 125 126 /* 127 * Extended exit -- 128 * Death of a lwp or process with optional bells and whistles. 129 * 130 * MPALMOSTSAFE 131 */ 132 int 133 sys_extexit(struct extexit_args *uap) 134 { 135 int action, who; 136 int error; 137 138 action = EXTEXIT_ACTION(uap->how); 139 who = EXTEXIT_WHO(uap->how); 140 141 /* Check parameters before we might perform some action */ 142 switch (who) { 143 case EXTEXIT_PROC: 144 case EXTEXIT_LWP: 145 break; 146 default: 147 return (EINVAL); 148 } 149 150 switch (action) { 151 case EXTEXIT_SIMPLE: 152 break; 153 case EXTEXIT_SETINT: 154 error = copyout(&uap->status, uap->addr, sizeof(uap->status)); 155 if (error) 156 return (error); 157 break; 158 default: 159 return (EINVAL); 160 } 161 162 get_mplock(); 163 164 switch (who) { 165 case EXTEXIT_LWP: 166 /* 167 * Be sure only to perform a simple lwp exit if there is at 168 * least one more lwp in the proc, which will call exit1() 169 * later, otherwise the proc will be an UNDEAD and not even a 170 * SZOMB! 171 */ 172 if (curproc->p_nthreads > 1) { 173 lwp_exit(0); 174 /* NOT REACHED */ 175 } 176 /* else last lwp in proc: do the real thing */ 177 /* FALLTHROUGH */ 178 default: /* to help gcc */ 179 case EXTEXIT_PROC: 180 exit1(W_EXITCODE(uap->status, 0)); 181 /* NOTREACHED */ 182 } 183 184 /* NOTREACHED */ 185 rel_mplock(); /* safety */ 186 } 187 188 /* 189 * Kill all lwps associated with the current process except the 190 * current lwp. Return an error if we race another thread trying to 191 * do the same thing and lose the race. 192 * 193 * If forexec is non-zero the current thread and process flags are 194 * cleaned up so they can be reused. 195 */ 196 int 197 killalllwps(int forexec) 198 { 199 struct lwp *lp = curthread->td_lwp; 200 struct proc *p = lp->lwp_proc; 201 202 /* 203 * Interlock against P_WEXIT. Only one of the process's thread 204 * is allowed to do the master exit. 205 */ 206 if (p->p_flag & P_WEXIT) 207 return (EALREADY); 208 p->p_flag |= P_WEXIT; 209 210 /* 211 * Interlock with LWP_WEXIT and kill any remaining LWPs 212 */ 213 lp->lwp_flag |= LWP_WEXIT; 214 if (p->p_nthreads > 1) 215 killlwps(lp); 216 217 /* 218 * If doing this for an exec, clean up the remaining thread 219 * (us) for continuing operation after all the other threads 220 * have been killed. 221 */ 222 if (forexec) { 223 lp->lwp_flag &= ~LWP_WEXIT; 224 p->p_flag &= ~P_WEXIT; 225 } 226 return(0); 227 } 228 229 /* 230 * Kill all LWPs except the current one. Do not try to signal 231 * LWPs which have exited on their own or have already been 232 * signaled. 233 */ 234 static void 235 killlwps(struct lwp *lp) 236 { 237 struct proc *p = lp->lwp_proc; 238 struct lwp *tlp; 239 240 /* 241 * Kill the remaining LWPs. We must send the signal before setting 242 * LWP_WEXIT. The setting of WEXIT is optional but helps reduce 243 * races. tlp must be held across the call as it might block and 244 * allow the target lwp to rip itself out from under our loop. 245 */ 246 FOREACH_LWP_IN_PROC(tlp, p) { 247 LWPHOLD(tlp); 248 if ((tlp->lwp_flag & LWP_WEXIT) == 0) { 249 lwpsignal(p, tlp, SIGKILL); 250 tlp->lwp_flag |= LWP_WEXIT; 251 } 252 LWPRELE(tlp); 253 } 254 255 /* 256 * Wait for everything to clear out. 257 */ 258 while (p->p_nthreads > 1) { 259 tsleep(&p->p_nthreads, 0, "killlwps", 0); 260 } 261 } 262 263 /* 264 * Exit: deallocate address space and other resources, change proc state 265 * to zombie, and unlink proc from allproc and parent's lists. Save exit 266 * status and rusage for wait(). Check for child processes and orphan them. 267 */ 268 void 269 exit1(int rv) 270 { 271 struct thread *td = curthread; 272 struct proc *p = td->td_proc; 273 struct lwp *lp = td->td_lwp; 274 struct proc *q, *nq; 275 struct vmspace *vm; 276 struct vnode *vtmp; 277 struct exitlist *ep; 278 int error; 279 280 if (p->p_pid == 1) { 281 kprintf("init died (signal %d, exit %d)\n", 282 WTERMSIG(rv), WEXITSTATUS(rv)); 283 panic("Going nowhere without my init!"); 284 } 285 286 varsymset_clean(&p->p_varsymset); 287 lockuninit(&p->p_varsymset.vx_lock); 288 /* 289 * Kill all lwps associated with the current process, return an 290 * error if we race another thread trying to do the same thing 291 * and lose the race. 292 */ 293 error = killalllwps(0); 294 if (error) { 295 lwp_exit(0); 296 /* NOT REACHED */ 297 } 298 299 caps_exit(lp->lwp_thread); 300 aio_proc_rundown(p); 301 302 /* are we a task leader? */ 303 if (p == p->p_leader) { 304 struct kill_args killArgs; 305 killArgs.signum = SIGKILL; 306 q = p->p_peers; 307 while(q) { 308 killArgs.pid = q->p_pid; 309 /* 310 * The interface for kill is better 311 * than the internal signal 312 */ 313 sys_kill(&killArgs); 314 nq = q; 315 q = q->p_peers; 316 } 317 while (p->p_peers) 318 tsleep((caddr_t)p, 0, "exit1", 0); 319 } 320 321 #ifdef PGINPROF 322 vmsizmon(); 323 #endif 324 STOPEVENT(p, S_EXIT, rv); 325 wakeup(&p->p_stype); /* Wakeup anyone in procfs' PIOCWAIT */ 326 327 /* 328 * Check if any loadable modules need anything done at process exit. 329 * e.g. SYSV IPC stuff 330 * XXX what if one of these generates an error? 331 */ 332 p->p_xstat = rv; 333 EVENTHANDLER_INVOKE(process_exit, p); 334 335 /* 336 * XXX: imho, the eventhandler stuff is much cleaner than this. 337 * Maybe we should move everything to use eventhandler. 338 */ 339 TAILQ_FOREACH(ep, &exit_list, next) 340 (*ep->function)(td); 341 342 if (p->p_flag & P_PROFIL) 343 stopprofclock(p); 344 /* 345 * If parent is waiting for us to exit or exec, 346 * P_PPWAIT is set; we will wakeup the parent below. 347 */ 348 p->p_flag &= ~(P_TRACED | P_PPWAIT); 349 SIGEMPTYSET(p->p_siglist); 350 SIGEMPTYSET(lp->lwp_siglist); 351 if (timevalisset(&p->p_realtimer.it_value)) 352 callout_stop(&p->p_ithandle); 353 354 /* 355 * Reset any sigio structures pointing to us as a result of 356 * F_SETOWN with our pid. 357 */ 358 funsetownlst(&p->p_sigiolst); 359 360 /* 361 * Close open files and release open-file table. 362 * This may block! 363 */ 364 fdfree(p, NULL); 365 366 if(p->p_leader->p_peers) { 367 q = p->p_leader; 368 while(q->p_peers != p) 369 q = q->p_peers; 370 q->p_peers = p->p_peers; 371 wakeup((caddr_t)p->p_leader); 372 } 373 374 /* 375 * XXX Shutdown SYSV semaphores 376 */ 377 semexit(p); 378 379 KKASSERT(p->p_numposixlocks == 0); 380 381 /* The next two chunks should probably be moved to vmspace_exit. */ 382 vm = p->p_vmspace; 383 384 /* 385 * Release upcalls associated with this process 386 */ 387 if (vm->vm_upcalls) 388 upc_release(vm, lp); 389 390 /* 391 * Clean up data related to virtual kernel operation. Clean up 392 * any vkernel context related to the current lwp now so we can 393 * destroy p_vkernel. 394 */ 395 if (p->p_vkernel) { 396 vkernel_lwp_exit(lp); 397 vkernel_exit(p); 398 } 399 400 /* 401 * Release user portion of address space. 402 * This releases references to vnodes, 403 * which could cause I/O if the file has been unlinked. 404 * Need to do this early enough that we can still sleep. 405 * Can't free the entire vmspace as the kernel stack 406 * may be mapped within that space also. 407 * 408 * Processes sharing the same vmspace may exit in one order, and 409 * get cleaned up by vmspace_exit() in a different order. The 410 * last exiting process to reach this point releases as much of 411 * the environment as it can, and the last process cleaned up 412 * by vmspace_exit() (which decrements exitingcnt) cleans up the 413 * remainder. 414 */ 415 vmspace_exitbump(vm); 416 sysref_put(&vm->vm_sysref); 417 418 if (SESS_LEADER(p)) { 419 struct session *sp = p->p_session; 420 421 if (sp->s_ttyvp) { 422 /* 423 * We are the controlling process. Signal the 424 * foreground process group, drain the controlling 425 * terminal, and revoke access to the controlling 426 * terminal. 427 * 428 * NOTE: while waiting for the process group to exit 429 * it is possible that one of the processes in the 430 * group will revoke the tty, so the ttyclosesession() 431 * function will re-check sp->s_ttyvp. 432 */ 433 if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) { 434 if (sp->s_ttyp->t_pgrp) 435 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1); 436 ttywait(sp->s_ttyp); 437 ttyclosesession(sp, 1); /* also revoke */ 438 } 439 /* 440 * Release the tty. If someone has it open via 441 * /dev/tty then close it (since they no longer can 442 * once we've NULL'd it out). 443 */ 444 ttyclosesession(sp, 0); 445 446 /* 447 * s_ttyp is not zero'd; we use this to indicate 448 * that the session once had a controlling terminal. 449 * (for logging and informational purposes) 450 */ 451 } 452 sp->s_leader = NULL; 453 } 454 fixjobc(p, p->p_pgrp, 0); 455 (void)acct_process(p); 456 #ifdef KTRACE 457 /* 458 * release trace file 459 */ 460 if (p->p_tracenode) 461 ktrdestroy(&p->p_tracenode); 462 p->p_traceflag = 0; 463 #endif 464 /* 465 * Release reference to text vnode 466 */ 467 if ((vtmp = p->p_textvp) != NULL) { 468 p->p_textvp = NULL; 469 vrele(vtmp); 470 } 471 472 /* Release namecache handle to text file */ 473 if (p->p_textnch.ncp) 474 cache_drop(&p->p_textnch); 475 476 /* 477 * Move the process to the zombie list. This will block 478 * until the process p_lock count reaches 0. The process will 479 * not be reaped until TDF_EXITING is set by cpu_thread_exit(), 480 * which is called from cpu_proc_exit(). 481 */ 482 proc_move_allproc_zombie(p); 483 484 q = LIST_FIRST(&p->p_children); 485 if (q) /* only need this if any child is S_ZOMB */ 486 wakeup((caddr_t) initproc); 487 for (; q != 0; q = nq) { 488 nq = LIST_NEXT(q, p_sibling); 489 LIST_REMOVE(q, p_sibling); 490 LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling); 491 q->p_pptr = initproc; 492 q->p_sigparent = SIGCHLD; 493 /* 494 * Traced processes are killed 495 * since their existence means someone is screwing up. 496 */ 497 if (q->p_flag & P_TRACED) { 498 q->p_flag &= ~P_TRACED; 499 ksignal(q, SIGKILL); 500 } 501 } 502 503 /* 504 * Save exit status and final rusage info, adding in child rusage 505 * info and self times. 506 */ 507 calcru_proc(p, &p->p_ru); 508 ruadd(&p->p_ru, &p->p_cru); 509 510 /* 511 * notify interested parties of our demise. 512 */ 513 KNOTE(&p->p_klist, NOTE_EXIT); 514 515 /* 516 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT 517 * flag set, notify process 1 instead (and hope it will handle 518 * this situation). 519 */ 520 if (p->p_pptr->p_sigacts->ps_flag & PS_NOCLDWAIT) { 521 struct proc *pp = p->p_pptr; 522 proc_reparent(p, initproc); 523 /* 524 * If this was the last child of our parent, notify 525 * parent, so in case he was wait(2)ing, he will 526 * continue. 527 */ 528 if (LIST_EMPTY(&pp->p_children)) 529 wakeup((caddr_t)pp); 530 } 531 532 if (p->p_sigparent && p->p_pptr != initproc) { 533 ksignal(p->p_pptr, p->p_sigparent); 534 } else { 535 ksignal(p->p_pptr, SIGCHLD); 536 } 537 538 wakeup((caddr_t)p->p_pptr); 539 /* 540 * cpu_exit is responsible for clearing curproc, since 541 * it is heavily integrated with the thread/switching sequence. 542 * 543 * Other substructures are freed from wait(). 544 */ 545 plimit_free(p); 546 547 /* 548 * Release the current user process designation on the process so 549 * the userland scheduler can work in someone else. 550 */ 551 p->p_usched->release_curproc(lp); 552 553 /* 554 * Finally, call machine-dependent code to release as many of the 555 * lwp's resources as we can and halt execution of this thread. 556 */ 557 lwp_exit(1); 558 } 559 560 /* 561 * Eventually called by every exiting LWP 562 */ 563 void 564 lwp_exit(int masterexit) 565 { 566 struct thread *td = curthread; 567 struct lwp *lp = td->td_lwp; 568 struct proc *p = lp->lwp_proc; 569 570 /* 571 * lwp_exit() may be called without setting LWP_WEXIT, so 572 * make sure it is set here. 573 */ 574 lp->lwp_flag |= LWP_WEXIT; 575 576 /* 577 * Clean up any virtualization 578 */ 579 if (lp->lwp_vkernel) 580 vkernel_lwp_exit(lp); 581 582 /* 583 * Clean up select/poll support 584 */ 585 kqueue_terminate(&lp->lwp_kqueue); 586 587 /* 588 * Clean up any syscall-cached ucred 589 */ 590 if (td->td_ucred) { 591 crfree(td->td_ucred); 592 td->td_ucred = NULL; 593 } 594 595 /* 596 * Nobody actually wakes us when the lock 597 * count reaches zero, so just wait one tick. 598 */ 599 while (lp->lwp_lock > 0) 600 tsleep(lp, 0, "lwpexit", 1); 601 602 /* Hand down resource usage to our proc */ 603 ruadd(&p->p_ru, &lp->lwp_ru); 604 605 /* 606 * If we don't hold the process until the LWP is reaped wait*() 607 * may try to dispose of its vmspace before all the LWPs have 608 * actually terminated. 609 */ 610 PHOLD(p); 611 612 /* 613 * We have to use the reaper for all the LWPs except the one doing 614 * the master exit. The LWP doing the master exit can just be 615 * left on p_lwps and the process reaper will deal with it 616 * synchronously, which is much faster. 617 */ 618 if (masterexit == 0) { 619 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 620 --p->p_nthreads; 621 wakeup(&p->p_nthreads); 622 LIST_INSERT_HEAD(&deadlwp_list[mycpuid], lp, u.lwp_reap_entry); 623 taskqueue_enqueue(taskqueue_thread[mycpuid], deadlwp_task[mycpuid]); 624 } else { 625 --p->p_nthreads; 626 } 627 biosched_done(curthread); 628 cpu_lwp_exit(); 629 } 630 631 /* 632 * Wait until a lwp is completely dead. 633 * 634 * If the thread is still executing, which can't be waited upon, 635 * return failure. The caller is responsible of waiting a little 636 * bit and checking again. 637 * 638 * Suggested use: 639 * while (!lwp_wait(lp)) 640 * tsleep(lp, 0, "lwpwait", 1); 641 */ 642 static int 643 lwp_wait(struct lwp *lp) 644 { 645 struct thread *td = lp->lwp_thread;; 646 647 KKASSERT(lwkt_preempted_proc() != lp); 648 649 while (lp->lwp_lock > 0) 650 tsleep(lp, 0, "lwpwait1", 1); 651 652 lwkt_wait_free(td); 653 654 /* 655 * The lwp's thread may still be in the middle 656 * of switching away, we can't rip its stack out from 657 * under it until TDF_EXITING is set and both 658 * TDF_RUNNING and TDF_PREEMPT_LOCK are clear. 659 * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING 660 * will be cleared temporarily if a thread gets 661 * preempted. 662 * 663 * YYY no wakeup occurs, so we simply return failure 664 * and let the caller deal with sleeping and calling 665 * us again. 666 */ 667 if ((td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|TDF_EXITING)) != 668 TDF_EXITING) 669 return (0); 670 671 return (1); 672 } 673 674 /* 675 * Release the resources associated with a lwp. 676 * The lwp must be completely dead. 677 */ 678 void 679 lwp_dispose(struct lwp *lp) 680 { 681 struct thread *td = lp->lwp_thread;; 682 683 KKASSERT(lwkt_preempted_proc() != lp); 684 KKASSERT(td->td_refs == 0); 685 KKASSERT((td->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|TDF_EXITING)) == 686 TDF_EXITING); 687 688 PRELE(lp->lwp_proc); 689 lp->lwp_proc = NULL; 690 if (td != NULL) { 691 td->td_proc = NULL; 692 td->td_lwp = NULL; 693 lp->lwp_thread = NULL; 694 lwkt_free_thread(td); 695 } 696 kfree(lp, M_LWP); 697 } 698 699 /* 700 * MPSAFE 701 */ 702 int 703 sys_wait4(struct wait_args *uap) 704 { 705 struct rusage rusage; 706 int error, status; 707 708 error = kern_wait(uap->pid, (uap->status ? &status : NULL), 709 uap->options, (uap->rusage ? &rusage : NULL), 710 &uap->sysmsg_result); 711 712 if (error == 0 && uap->status) 713 error = copyout(&status, uap->status, sizeof(*uap->status)); 714 if (error == 0 && uap->rusage) 715 error = copyout(&rusage, uap->rusage, sizeof(*uap->rusage)); 716 return (error); 717 } 718 719 /* 720 * wait1() 721 * 722 * wait_args(int pid, int *status, int options, struct rusage *rusage) 723 * 724 * MPALMOSTSAFE 725 */ 726 int 727 kern_wait(pid_t pid, int *status, int options, struct rusage *rusage, int *res) 728 { 729 struct thread *td = curthread; 730 struct lwp *lp; 731 struct proc *q = td->td_proc; 732 struct proc *p, *t; 733 int nfound, error; 734 735 if (pid == 0) 736 pid = -q->p_pgid; 737 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WLINUXCLONE)) 738 return (EINVAL); 739 get_mplock(); 740 loop: 741 /* 742 * Hack for backwards compatibility with badly written user code. 743 * Or perhaps we have to do this anyway, it is unclear. XXX 744 * 745 * The problem is that if a process group is stopped and the parent 746 * is doing a wait*(..., WUNTRACED, ...), it will see the STOP 747 * of the child and then stop itself when it tries to return from the 748 * system call. When the process group is resumed the parent will 749 * then get the STOP status even though the child has now resumed 750 * (a followup wait*() will get the CONT status). 751 * 752 * Previously the CONT would overwrite the STOP because the tstop 753 * was handled within tsleep(), and the parent would only see 754 * the CONT when both are stopped and continued together. This litte 755 * two-line hack restores this effect. 756 */ 757 while (q->p_stat == SSTOP) 758 tstop(); 759 760 nfound = 0; 761 LIST_FOREACH(p, &q->p_children, p_sibling) { 762 if (pid != WAIT_ANY && 763 p->p_pid != pid && p->p_pgid != -pid) 764 continue; 765 766 /* This special case handles a kthread spawned by linux_clone 767 * (see linux_misc.c). The linux_wait4 and linux_waitpid 768 * functions need to be able to distinguish between waiting 769 * on a process and waiting on a thread. It is a thread if 770 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option 771 * signifies we want to wait for threads and not processes. 772 */ 773 if ((p->p_sigparent != SIGCHLD) ^ 774 ((options & WLINUXCLONE) != 0)) { 775 continue; 776 } 777 778 nfound++; 779 if (p->p_stat == SZOMB) { 780 /* 781 * We may go into SZOMB with threads still present. 782 * We must wait for them to exit before we can reap 783 * the master thread, otherwise we may race reaping 784 * non-master threads. 785 */ 786 while (p->p_nthreads > 0) { 787 tsleep(&p->p_nthreads, 0, "lwpzomb", hz); 788 } 789 790 /* 791 * Reap any LWPs left in p->p_lwps. This is usually 792 * just the last LWP. This must be done before 793 * we loop on p_lock since the lwps hold a ref on 794 * it as a vmspace interlock. 795 * 796 * Once that is accomplished p_nthreads had better 797 * be zero. 798 */ 799 while ((lp = RB_ROOT(&p->p_lwp_tree)) != NULL) { 800 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp); 801 reaplwp(lp); 802 } 803 KKASSERT(p->p_nthreads == 0); 804 805 /* 806 * Don't do anything really bad until all references 807 * to the process go away. This may include other 808 * LWPs which are still in the process of being 809 * reaped. We can't just pull the rug out from under 810 * them because they may still be using the VM space. 811 * 812 * Certain kernel facilities such as /proc will also 813 * put a hold on the process for short periods of 814 * time. 815 */ 816 while (p->p_lock) 817 tsleep(p, 0, "reap3", hz); 818 819 /* scheduling hook for heuristic */ 820 /* XXX no lwp available, we need a different heuristic */ 821 /* 822 p->p_usched->heuristic_exiting(td->td_lwp, deadlp); 823 */ 824 825 /* Take care of our return values. */ 826 *res = p->p_pid; 827 if (status) 828 *status = p->p_xstat; 829 if (rusage) 830 *rusage = p->p_ru; 831 /* 832 * If we got the child via a ptrace 'attach', 833 * we need to give it back to the old parent. 834 */ 835 if (p->p_oppid && (t = pfind(p->p_oppid))) { 836 p->p_oppid = 0; 837 proc_reparent(p, t); 838 ksignal(t, SIGCHLD); 839 wakeup((caddr_t)t); 840 error = 0; 841 goto done; 842 } 843 844 /* 845 * Unlink the proc from its process group so that 846 * the following operations won't lead to an 847 * inconsistent state for processes running down 848 * the zombie list. 849 */ 850 KKASSERT(p->p_lock == 0); 851 proc_remove_zombie(p); 852 leavepgrp(p); 853 854 p->p_xstat = 0; 855 ruadd(&q->p_cru, &p->p_ru); 856 857 /* 858 * Decrement the count of procs running with this uid. 859 */ 860 chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0); 861 862 /* 863 * Free up credentials. 864 */ 865 crfree(p->p_ucred); 866 p->p_ucred = NULL; 867 868 /* 869 * Remove unused arguments 870 */ 871 if (p->p_args && --p->p_args->ar_ref == 0) 872 FREE(p->p_args, M_PARGS); 873 874 if (--p->p_sigacts->ps_refcnt == 0) { 875 kfree(p->p_sigacts, M_SUBPROC); 876 p->p_sigacts = NULL; 877 } 878 879 vm_waitproc(p); 880 kfree(p, M_PROC); 881 nprocs--; 882 error = 0; 883 goto done; 884 } 885 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 886 (p->p_flag & P_TRACED || options & WUNTRACED)) { 887 p->p_flag |= P_WAITED; 888 889 *res = p->p_pid; 890 if (status) 891 *status = W_STOPCODE(p->p_xstat); 892 /* Zero rusage so we get something consistent. */ 893 if (rusage) 894 bzero(rusage, sizeof(rusage)); 895 error = 0; 896 goto done; 897 } 898 if (options & WCONTINUED && (p->p_flag & P_CONTINUED)) { 899 *res = p->p_pid; 900 p->p_flag &= ~P_CONTINUED; 901 902 if (status) 903 *status = SIGCONT; 904 error = 0; 905 goto done; 906 } 907 } 908 if (nfound == 0) { 909 error = ECHILD; 910 goto done; 911 } 912 if (options & WNOHANG) { 913 *res = 0; 914 error = 0; 915 goto done; 916 } 917 error = tsleep((caddr_t)q, PCATCH, "wait", 0); 918 if (error) { 919 done: 920 rel_mplock(); 921 return (error); 922 } 923 goto loop; 924 } 925 926 /* 927 * make process 'parent' the new parent of process 'child'. 928 */ 929 void 930 proc_reparent(struct proc *child, struct proc *parent) 931 { 932 933 if (child->p_pptr == parent) 934 return; 935 936 LIST_REMOVE(child, p_sibling); 937 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 938 child->p_pptr = parent; 939 } 940 941 /* 942 * The next two functions are to handle adding/deleting items on the 943 * exit callout list 944 * 945 * at_exit(): 946 * Take the arguments given and put them onto the exit callout list, 947 * However first make sure that it's not already there. 948 * returns 0 on success. 949 */ 950 951 int 952 at_exit(exitlist_fn function) 953 { 954 struct exitlist *ep; 955 956 #ifdef INVARIANTS 957 /* Be noisy if the programmer has lost track of things */ 958 if (rm_at_exit(function)) 959 kprintf("WARNING: exit callout entry (%p) already present\n", 960 function); 961 #endif 962 ep = kmalloc(sizeof(*ep), M_ATEXIT, M_NOWAIT); 963 if (ep == NULL) 964 return (ENOMEM); 965 ep->function = function; 966 TAILQ_INSERT_TAIL(&exit_list, ep, next); 967 return (0); 968 } 969 970 /* 971 * Scan the exit callout list for the given item and remove it. 972 * Returns the number of items removed (0 or 1) 973 */ 974 int 975 rm_at_exit(exitlist_fn function) 976 { 977 struct exitlist *ep; 978 979 TAILQ_FOREACH(ep, &exit_list, next) { 980 if (ep->function == function) { 981 TAILQ_REMOVE(&exit_list, ep, next); 982 kfree(ep, M_ATEXIT); 983 return(1); 984 } 985 } 986 return (0); 987 } 988 989 /* 990 * LWP reaper related code. 991 */ 992 static void 993 reaplwps(void *context, int dummy) 994 { 995 struct lwplist *lwplist = context; 996 struct lwp *lp; 997 998 get_mplock(); 999 while ((lp = LIST_FIRST(lwplist))) { 1000 LIST_REMOVE(lp, u.lwp_reap_entry); 1001 reaplwp(lp); 1002 } 1003 rel_mplock(); 1004 } 1005 1006 static void 1007 reaplwp(struct lwp *lp) 1008 { 1009 while (lwp_wait(lp) == 0) 1010 tsleep(lp, 0, "lwpreap", 1); 1011 lwp_dispose(lp); 1012 } 1013 1014 static void 1015 deadlwp_init(void) 1016 { 1017 int cpu; 1018 1019 for (cpu = 0; cpu < ncpus; cpu++) { 1020 LIST_INIT(&deadlwp_list[cpu]); 1021 deadlwp_task[cpu] = kmalloc(sizeof(*deadlwp_task[cpu]), M_DEVBUF, M_WAITOK); 1022 TASK_INIT(deadlwp_task[cpu], 0, reaplwps, &deadlwp_list[cpu]); 1023 } 1024 } 1025 1026 SYSINIT(deadlwpinit, SI_SUB_CONFIGURE, SI_ORDER_ANY, deadlwp_init, NULL); 1027