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 * $FreeBSD$ 40 */ 41 42 #include "opt_compat.h" 43 #include "opt_ktrace.h" 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/sysproto.h> 48 #include <sys/kernel.h> 49 #include <sys/malloc.h> 50 #include <sys/lock.h> 51 #include <sys/mutex.h> 52 #include <sys/proc.h> 53 #include <sys/pioctl.h> 54 #include <sys/tty.h> 55 #include <sys/wait.h> 56 #include <sys/vnode.h> 57 #include <sys/vmmeter.h> 58 #include <sys/resourcevar.h> 59 #include <sys/signalvar.h> 60 #include <sys/sx.h> 61 #include <sys/ptrace.h> 62 #include <sys/acct.h> /* for acct_process() function prototype */ 63 #include <sys/filedesc.h> 64 #include <sys/shm.h> 65 #include <sys/sem.h> 66 #include <sys/aio.h> 67 #include <sys/jail.h> 68 69 #include <vm/vm.h> 70 #include <vm/vm_param.h> 71 #include <vm/vm_extern.h> 72 #include <vm/pmap.h> 73 #include <vm/vm_map.h> 74 #include <vm/vm_zone.h> 75 #include <sys/user.h> 76 77 /* Required to be non-static for SysVR4 emulator */ 78 MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status"); 79 80 static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback"); 81 82 static int wait1 __P((struct thread *, struct wait_args *, int)); 83 84 /* 85 * callout list for things to do at exit time 86 */ 87 struct exitlist { 88 exitlist_fn function; 89 TAILQ_ENTRY(exitlist) next; 90 }; 91 92 TAILQ_HEAD(exit_list_head, exitlist); 93 static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list); 94 95 /* 96 * exit -- 97 * Death of process. 98 * 99 * MPSAFE 100 */ 101 void 102 sys_exit(td, uap) 103 struct thread *td; 104 struct sys_exit_args /* { 105 int rval; 106 } */ *uap; 107 { 108 109 mtx_lock(&Giant); 110 exit1(td, W_EXITCODE(uap->rval, 0)); 111 /* NOTREACHED */ 112 } 113 114 /* 115 * Exit: deallocate address space and other resources, change proc state 116 * to zombie, and unlink proc from allproc and parent's lists. Save exit 117 * status and rusage for wait(). Check for child processes and orphan them. 118 */ 119 void 120 exit1(td, rv) 121 register struct thread *td; 122 int rv; 123 { 124 struct proc *p = td->td_proc; 125 register struct proc *q, *nq; 126 register struct vmspace *vm; 127 struct exitlist *ep; 128 129 GIANT_REQUIRED; 130 131 if (p->p_pid == 1) { 132 printf("init died (signal %d, exit %d)\n", 133 WTERMSIG(rv), WEXITSTATUS(rv)); 134 panic("Going nowhere without my init!"); 135 } 136 137 /* XXXXKSE */ 138 /* MUST abort all other threads before proceeding past this point */ 139 140 aio_proc_rundown(p); 141 142 /* are we a task leader? */ 143 PROC_LOCK(p); 144 if(p == p->p_leader) { 145 q = p->p_peers; 146 while (q != NULL) { 147 PROC_LOCK(q); 148 psignal(q, SIGKILL); 149 PROC_UNLOCK(q); 150 q = q->p_peers; 151 } 152 while (p->p_peers) 153 msleep((caddr_t)p, &p->p_mtx, PWAIT, "exit1", 0); 154 } 155 PROC_UNLOCK(p); 156 157 #ifdef PGINPROF 158 vmsizmon(); 159 #endif 160 STOPEVENT(p, S_EXIT, rv); 161 wakeup(&p->p_stype); /* Wakeup anyone in procfs' PIOCWAIT */ 162 163 /* 164 * Check if any loadable modules need anything done at process exit. 165 * e.g. SYSV IPC stuff 166 * XXX what if one of these generates an error? 167 */ 168 TAILQ_FOREACH(ep, &exit_list, next) 169 (*ep->function)(p); 170 171 stopprofclock(p); 172 173 MALLOC(p->p_ru, struct rusage *, sizeof(struct rusage), 174 M_ZOMBIE, M_WAITOK); 175 /* 176 * If parent is waiting for us to exit or exec, 177 * P_PPWAIT is set; we will wakeup the parent below. 178 */ 179 PROC_LOCK(p); 180 p->p_flag &= ~(P_TRACED | P_PPWAIT); 181 p->p_flag |= P_WEXIT; 182 SIGEMPTYSET(p->p_siglist); 183 PROC_UNLOCK(p); 184 if (timevalisset(&p->p_realtimer.it_value)) 185 callout_stop(&p->p_itcallout); 186 187 /* 188 * Reset any sigio structures pointing to us as a result of 189 * F_SETOWN with our pid. 190 */ 191 funsetownlst(&p->p_sigiolst); 192 193 /* 194 * Close open files and release open-file table. 195 * This may block! 196 */ 197 fdfree(&p->p_thread); /* XXXKSE */ 198 199 /* 200 * Remove ourself from our leader's peer list and wake our leader. 201 */ 202 PROC_LOCK(p->p_leader); 203 if(p->p_leader->p_peers) { 204 q = p->p_leader; 205 while(q->p_peers != p) 206 q = q->p_peers; 207 q->p_peers = p->p_peers; 208 wakeup((caddr_t)p->p_leader); 209 } 210 PROC_UNLOCK(p->p_leader); 211 212 /* 213 * XXX Shutdown SYSV semaphores 214 */ 215 semexit(p); 216 217 /* The next two chunks should probably be moved to vmspace_exit. */ 218 vm = p->p_vmspace; 219 /* 220 * Release user portion of address space. 221 * This releases references to vnodes, 222 * which could cause I/O if the file has been unlinked. 223 * Need to do this early enough that we can still sleep. 224 * Can't free the entire vmspace as the kernel stack 225 * may be mapped within that space also. 226 */ 227 if (vm->vm_refcnt == 1) { 228 if (vm->vm_shm) 229 shmexit(p); 230 pmap_remove_pages(vmspace_pmap(vm), VM_MIN_ADDRESS, 231 VM_MAXUSER_ADDRESS); 232 (void) vm_map_remove(&vm->vm_map, VM_MIN_ADDRESS, 233 VM_MAXUSER_ADDRESS); 234 } 235 236 PROC_LOCK(p); 237 if (SESS_LEADER(p)) { 238 register struct session *sp = p->p_session; 239 240 PROC_UNLOCK(p); 241 if (sp->s_ttyvp) { 242 /* 243 * Controlling process. 244 * Signal foreground pgrp, 245 * drain controlling terminal 246 * and revoke access to controlling terminal. 247 */ 248 if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) { 249 if (sp->s_ttyp->t_pgrp) 250 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1); 251 (void) ttywait(sp->s_ttyp); 252 /* 253 * The tty could have been revoked 254 * if we blocked. 255 */ 256 if (sp->s_ttyvp) 257 VOP_REVOKE(sp->s_ttyvp, REVOKEALL); 258 } 259 if (sp->s_ttyvp) 260 vrele(sp->s_ttyvp); 261 sp->s_ttyvp = NULL; 262 /* 263 * s_ttyp is not zero'd; we use this to indicate 264 * that the session once had a controlling terminal. 265 * (for logging and informational purposes) 266 */ 267 } 268 sp->s_leader = NULL; 269 } else 270 PROC_UNLOCK(p); 271 fixjobc(p, p->p_pgrp, 0); 272 (void)acct_process(td); 273 #ifdef KTRACE 274 /* 275 * release trace file 276 */ 277 p->p_traceflag = 0; /* don't trace the vrele() */ 278 if (p->p_tracep) 279 vrele(p->p_tracep); 280 #endif 281 /* 282 * Remove proc from allproc queue and pidhash chain. 283 * Place onto zombproc. Unlink from parent's child list. 284 */ 285 sx_xlock(&allproc_lock); 286 LIST_REMOVE(p, p_list); 287 LIST_INSERT_HEAD(&zombproc, p, p_list); 288 LIST_REMOVE(p, p_hash); 289 sx_xunlock(&allproc_lock); 290 291 sx_xlock(&proctree_lock); 292 q = LIST_FIRST(&p->p_children); 293 if (q != NULL) /* only need this if any child is S_ZOMB */ 294 wakeup((caddr_t) initproc); 295 for (; q != NULL; q = nq) { 296 nq = LIST_NEXT(q, p_sibling); 297 PROC_LOCK(q); 298 proc_reparent(q, initproc); 299 q->p_sigparent = SIGCHLD; 300 /* 301 * Traced processes are killed 302 * since their existence means someone is screwing up. 303 */ 304 if (q->p_flag & P_TRACED) { 305 q->p_flag &= ~P_TRACED; 306 psignal(q, SIGKILL); 307 } 308 PROC_UNLOCK(q); 309 } 310 311 /* 312 * Save exit status and final rusage info, adding in child rusage 313 * info and self times. 314 */ 315 p->p_xstat = rv; 316 *p->p_ru = p->p_stats->p_ru; 317 mtx_lock_spin(&sched_lock); 318 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL); 319 mtx_unlock_spin(&sched_lock); 320 ruadd(p->p_ru, &p->p_stats->p_cru); 321 322 /* 323 * Pretend that an mi_switch() to the next process occurs now. We 324 * must set `switchtime' directly since we will call cpu_switch() 325 * directly. Set it now so that the rest of the exit time gets 326 * counted somewhere if possible. 327 */ 328 mtx_lock_spin(&sched_lock); 329 microuptime(PCPU_PTR(switchtime)); 330 PCPU_SET(switchticks, ticks); 331 mtx_unlock_spin(&sched_lock); 332 333 /* 334 * notify interested parties of our demise. 335 */ 336 PROC_LOCK(p); 337 KNOTE(&p->p_klist, NOTE_EXIT); 338 339 /* 340 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT 341 * flag set, notify process 1 instead (and hope it will handle 342 * this situation). 343 */ 344 if (p->p_pptr->p_procsig->ps_flag & PS_NOCLDWAIT) { 345 struct proc *pp = p->p_pptr; 346 proc_reparent(p, initproc); 347 /* 348 * If this was the last child of our parent, notify 349 * parent, so in case he was wait(2)ing, he will 350 * continue. 351 */ 352 if (LIST_EMPTY(&pp->p_children)) 353 wakeup((caddr_t)pp); 354 } 355 356 PROC_LOCK(p->p_pptr); 357 if (p->p_sigparent && p->p_pptr != initproc) 358 psignal(p->p_pptr, p->p_sigparent); 359 else 360 psignal(p->p_pptr, SIGCHLD); 361 PROC_UNLOCK(p->p_pptr); 362 363 /* 364 * If this is a kthread, then wakeup anyone waiting for it to exit. 365 */ 366 if (p->p_flag & P_KTHREAD) 367 wakeup((caddr_t)p); 368 PROC_UNLOCK(p); 369 sx_xunlock(&proctree_lock); 370 371 /* 372 * Clear curproc after we've done all operations 373 * that could block, and before tearing down the rest 374 * of the process state that might be used from clock, etc. 375 * Also, can't clear curproc while we're still runnable, 376 * as we're not on a run queue (we are current, just not 377 * a proper proc any longer!). 378 * 379 * Other substructures are freed from wait(). 380 */ 381 mtx_assert(&Giant, MA_OWNED); 382 if (--p->p_limit->p_refcnt == 0) { 383 FREE(p->p_limit, M_SUBPROC); 384 p->p_limit = NULL; 385 } 386 387 /* 388 * Finally, call machine-dependent code to release the remaining 389 * resources including address space, the kernel stack and pcb. 390 * The address space is released by "vmspace_free(p->p_vmspace)" 391 * in vm_waitproc(); 392 */ 393 cpu_exit(td); 394 395 PROC_LOCK(p); 396 mtx_lock_spin(&sched_lock); 397 while (mtx_owned(&Giant)) 398 mtx_unlock_flags(&Giant, MTX_NOSWITCH); 399 400 /* 401 * We have to wait until after releasing all locks before 402 * changing p_stat. If we block on a mutex then we will be 403 * back at SRUN when we resume and our parent will never 404 * harvest us. 405 */ 406 p->p_stat = SZOMB; 407 408 wakeup(p->p_pptr); 409 PROC_UNLOCK_NOSWITCH(p); 410 411 cnt.v_swtch++; 412 cpu_throw(); 413 panic("exit1"); 414 } 415 416 #ifdef COMPAT_43 417 /* 418 * MPSAFE, the dirty work is handled by wait1(). 419 */ 420 int 421 owait(td, uap) 422 struct thread *td; 423 register struct owait_args /* { 424 int dummy; 425 } */ *uap; 426 { 427 struct wait_args w; 428 429 w.options = 0; 430 w.rusage = NULL; 431 w.pid = WAIT_ANY; 432 w.status = NULL; 433 return (wait1(td, &w, 1)); 434 } 435 #endif /* COMPAT_43 */ 436 437 /* 438 * MPSAFE, the dirty work is handled by wait1(). 439 */ 440 int 441 wait4(td, uap) 442 struct thread *td; 443 struct wait_args *uap; 444 { 445 446 return (wait1(td, uap, 0)); 447 } 448 449 /* 450 * MPSAFE 451 */ 452 static int 453 wait1(td, uap, compat) 454 register struct thread *td; 455 register struct wait_args /* { 456 int pid; 457 int *status; 458 int options; 459 struct rusage *rusage; 460 } */ *uap; 461 int compat; 462 { 463 register int nfound; 464 register struct proc *q, *p, *t; 465 int status, error; 466 467 mtx_lock(&Giant); 468 q = td->td_proc; 469 if (uap->pid == 0) 470 uap->pid = -q->p_pgid; 471 if (uap->options &~ (WUNTRACED|WNOHANG|WLINUXCLONE)) { 472 error = EINVAL; 473 goto done2; 474 } 475 loop: 476 nfound = 0; 477 sx_slock(&proctree_lock); 478 LIST_FOREACH(p, &q->p_children, p_sibling) { 479 if (uap->pid != WAIT_ANY && 480 p->p_pid != uap->pid && p->p_pgid != -uap->pid) 481 continue; 482 483 /* 484 * This special case handles a kthread spawned by linux_clone 485 * (see linux_misc.c). The linux_wait4 and linux_waitpid 486 * functions need to be able to distinguish between waiting 487 * on a process and waiting on a thread. It is a thread if 488 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option 489 * signifies we want to wait for threads and not processes. 490 */ 491 PROC_LOCK(p); 492 if ((p->p_sigparent != SIGCHLD) ^ 493 ((uap->options & WLINUXCLONE) != 0)) { 494 PROC_UNLOCK(p); 495 continue; 496 } 497 498 nfound++; 499 mtx_lock_spin(&sched_lock); 500 if (p->p_stat == SZOMB) { 501 /* 502 * charge childs scheduling cpu usage to parent 503 * XXXKSE assume only one thread & kse & ksegrp 504 * keep estcpu in each ksegrp 505 * so charge it to the ksegrp that did the wait 506 * since process estcpu is sum of all ksegrps, 507 * this is strictly as expected. 508 * Assume that the child process aggregated all 509 * tke estcpu into the 'build-in' ksegrp. 510 * XXXKSE 511 */ 512 if (curthread->td_proc->p_pid != 1) { 513 curthread->td_ksegrp->kg_estcpu = 514 ESTCPULIM(curthread->td_ksegrp->kg_estcpu + 515 p->p_ksegrp.kg_estcpu); 516 } 517 518 mtx_unlock_spin(&sched_lock); 519 PROC_UNLOCK(p); 520 sx_sunlock(&proctree_lock); 521 522 td->td_retval[0] = p->p_pid; 523 #ifdef COMPAT_43 524 if (compat) 525 td->td_retval[1] = p->p_xstat; 526 else 527 #endif 528 if (uap->status) { 529 status = p->p_xstat; /* convert to int */ 530 if ((error = copyout((caddr_t)&status, 531 (caddr_t)uap->status, sizeof(status)))) { 532 goto done2; 533 } 534 } 535 if (uap->rusage && (error = copyout((caddr_t)p->p_ru, 536 (caddr_t)uap->rusage, sizeof (struct rusage)))) { 537 goto done2; 538 } 539 /* 540 * If we got the child via a ptrace 'attach', 541 * we need to give it back to the old parent. 542 */ 543 sx_xlock(&proctree_lock); 544 if (p->p_oppid) { 545 if ((t = pfind(p->p_oppid)) != NULL) { 546 PROC_LOCK(p); 547 p->p_oppid = 0; 548 proc_reparent(p, t); 549 PROC_UNLOCK(p); 550 psignal(t, SIGCHLD); 551 wakeup((caddr_t)t); 552 PROC_UNLOCK(t); 553 sx_xunlock(&proctree_lock); 554 error = 0; 555 goto done2; 556 } 557 } 558 sx_xunlock(&proctree_lock); 559 PROC_LOCK(p); 560 p->p_xstat = 0; 561 PROC_UNLOCK(p); 562 ruadd(&q->p_stats->p_cru, p->p_ru); 563 FREE(p->p_ru, M_ZOMBIE); 564 p->p_ru = NULL; 565 566 /* 567 * Decrement the count of procs running with this uid. 568 */ 569 (void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0); 570 571 /* 572 * Release reference to text vnode 573 */ 574 if (p->p_textvp) 575 vrele(p->p_textvp); 576 577 /* 578 * Finally finished with old proc entry. 579 * Unlink it from its process group and free it. 580 */ 581 leavepgrp(p); 582 583 sx_xlock(&allproc_lock); 584 LIST_REMOVE(p, p_list); /* off zombproc */ 585 sx_xunlock(&allproc_lock); 586 587 sx_xlock(&proctree_lock); 588 LIST_REMOVE(p, p_sibling); 589 sx_xunlock(&proctree_lock); 590 591 /* 592 * Free up credentials. 593 */ 594 crfree(p->p_ucred); 595 p->p_ucred = NULL; 596 597 /* 598 * Remove unused arguments 599 */ 600 if (p->p_args && --p->p_args->ar_ref == 0) 601 FREE(p->p_args, M_PARGS); 602 603 if (--p->p_procsig->ps_refcnt == 0) { 604 if (p->p_sigacts != &p->p_uarea->u_sigacts) 605 FREE(p->p_sigacts, M_SUBPROC); 606 FREE(p->p_procsig, M_SUBPROC); 607 p->p_procsig = NULL; 608 } 609 610 /* 611 * Give vm and machine-dependent layer a chance 612 * to free anything that cpu_exit couldn't 613 * release while still running in process context. 614 */ 615 vm_waitproc(p); 616 mtx_destroy(&p->p_mtx); 617 zfree(proc_zone, p); 618 nprocs--; 619 error = 0; 620 goto done2; 621 } 622 if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 && 623 (p->p_flag & P_TRACED || uap->options & WUNTRACED)) { 624 mtx_unlock_spin(&sched_lock); 625 p->p_flag |= P_WAITED; 626 PROC_UNLOCK(p); 627 sx_sunlock(&proctree_lock); 628 td->td_retval[0] = p->p_pid; 629 #ifdef COMPAT_43 630 if (compat) { 631 td->td_retval[1] = W_STOPCODE(p->p_xstat); 632 error = 0; 633 } else 634 #endif 635 if (uap->status) { 636 status = W_STOPCODE(p->p_xstat); 637 error = copyout((caddr_t)&status, 638 (caddr_t)uap->status, sizeof(status)); 639 } else 640 error = 0; 641 goto done2; 642 } 643 mtx_unlock_spin(&sched_lock); 644 PROC_UNLOCK(p); 645 } 646 sx_sunlock(&proctree_lock); 647 if (nfound == 0) { 648 error = ECHILD; 649 goto done2; 650 } 651 if (uap->options & WNOHANG) { 652 td->td_retval[0] = 0; 653 error = 0; 654 goto done2; 655 } 656 if ((error = tsleep((caddr_t)q, PWAIT | PCATCH, "wait", 0)) != 0) 657 goto done2; 658 goto loop; 659 done2: 660 mtx_unlock(&Giant); 661 return(error); 662 } 663 664 /* 665 * Make process 'parent' the new parent of process 'child'. 666 * Must be called with an exclusive hold of proctree lock. 667 */ 668 void 669 proc_reparent(child, parent) 670 register struct proc *child; 671 register struct proc *parent; 672 { 673 674 SX_ASSERT_XLOCKED(&proctree_lock); 675 PROC_LOCK_ASSERT(child, MA_OWNED); 676 if (child->p_pptr == parent) 677 return; 678 679 LIST_REMOVE(child, p_sibling); 680 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 681 child->p_pptr = parent; 682 } 683 684 /* 685 * The next two functions are to handle adding/deleting items on the 686 * exit callout list 687 * 688 * at_exit(): 689 * Take the arguments given and put them onto the exit callout list, 690 * However first make sure that it's not already there. 691 * returns 0 on success. 692 */ 693 694 int 695 at_exit(function) 696 exitlist_fn function; 697 { 698 struct exitlist *ep; 699 700 #ifdef INVARIANTS 701 /* Be noisy if the programmer has lost track of things */ 702 if (rm_at_exit(function)) 703 printf("WARNING: exit callout entry (%p) already present\n", 704 function); 705 #endif 706 ep = malloc(sizeof(*ep), M_ATEXIT, M_NOWAIT); 707 if (ep == NULL) 708 return (ENOMEM); 709 ep->function = function; 710 TAILQ_INSERT_TAIL(&exit_list, ep, next); 711 return (0); 712 } 713 714 /* 715 * Scan the exit callout list for the given item and remove it. 716 * Returns the number of items removed (0 or 1) 717 */ 718 int 719 rm_at_exit(function) 720 exitlist_fn function; 721 { 722 struct exitlist *ep; 723 724 TAILQ_FOREACH(ep, &exit_list, next) { 725 if (ep->function == function) { 726 TAILQ_REMOVE(&exit_list, ep, next); 727 free(ep, M_ATEXIT); 728 return(1); 729 } 730 } 731 return (0); 732 } 733