The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exit.c

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    1 /*      $NetBSD: kern_exit.c,v 1.214.4.2 2009/07/01 22:30:30 snj Exp $  */
    2 
    3 /*-
    4  * Copyright (c) 1998, 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
    9  * NASA Ames Research Center, and by Andrew Doran.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   30  * POSSIBILITY OF SUCH DAMAGE.
   31  */
   32 
   33 /*
   34  * Copyright (c) 1982, 1986, 1989, 1991, 1993
   35  *      The Regents of the University of California.  All rights reserved.
   36  * (c) UNIX System Laboratories, Inc.
   37  * All or some portions of this file are derived from material licensed
   38  * to the University of California by American Telephone and Telegraph
   39  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   40  * the permission of UNIX System Laboratories, Inc.
   41  *
   42  * Redistribution and use in source and binary forms, with or without
   43  * modification, are permitted provided that the following conditions
   44  * are met:
   45  * 1. Redistributions of source code must retain the above copyright
   46  *    notice, this list of conditions and the following disclaimer.
   47  * 2. Redistributions in binary form must reproduce the above copyright
   48  *    notice, this list of conditions and the following disclaimer in the
   49  *    documentation and/or other materials provided with the distribution.
   50  * 3. Neither the name of the University nor the names of its contributors
   51  *    may be used to endorse or promote products derived from this software
   52  *    without specific prior written permission.
   53  *
   54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   64  * SUCH DAMAGE.
   65  *
   66  *      @(#)kern_exit.c 8.10 (Berkeley) 2/23/95
   67  */
   68 
   69 #include <sys/cdefs.h>
   70 __KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.214.4.2 2009/07/01 22:30:30 snj Exp $");
   71 
   72 #include "opt_ktrace.h"
   73 #include "opt_perfctrs.h"
   74 #include "opt_sa.h"
   75 #include "opt_sysv.h"
   76 
   77 #include <sys/param.h>
   78 #include <sys/aio.h>
   79 #include <sys/systm.h>
   80 #include <sys/ioctl.h>
   81 #include <sys/tty.h>
   82 #include <sys/time.h>
   83 #include <sys/resource.h>
   84 #include <sys/kernel.h>
   85 #include <sys/proc.h>
   86 #include <sys/buf.h>
   87 #include <sys/wait.h>
   88 #include <sys/file.h>
   89 #include <sys/vnode.h>
   90 #include <sys/syslog.h>
   91 #include <sys/malloc.h>
   92 #include <sys/pool.h>
   93 #include <sys/uidinfo.h>
   94 #if defined(PERFCTRS)
   95 #include <sys/pmc.h>
   96 #endif
   97 #include <sys/ptrace.h>
   98 #include <sys/acct.h>
   99 #include <sys/filedesc.h>
  100 #include <sys/ras.h>
  101 #include <sys/signalvar.h>
  102 #include <sys/sched.h>
  103 #include <sys/sa.h>
  104 #include <sys/savar.h>
  105 #include <sys/mount.h>
  106 #include <sys/syscallargs.h>
  107 #include <sys/kauth.h>
  108 #include <sys/sleepq.h>
  109 #include <sys/lockdebug.h>
  110 #include <sys/ktrace.h>
  111 #include <sys/cpu.h>
  112 #include <sys/lwpctl.h>
  113 #include <sys/atomic.h>
  114 
  115 #include <uvm/uvm_extern.h>
  116 
  117 #define DEBUG_EXIT
  118 
  119 #ifdef DEBUG_EXIT
  120 int debug_exit = 0;
  121 #define DPRINTF(x) if (debug_exit) printf x
  122 #else
  123 #define DPRINTF(x)
  124 #endif
  125 
  126 static int find_stopped_child(struct proc *, pid_t, int, struct proc **, int *);
  127 static void proc_free(struct proc *, struct rusage *);
  128 
  129 /*
  130  * Fill in the appropriate signal information, and signal the parent.
  131  */
  132 static void
  133 exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi)
  134 {
  135 
  136         KSI_INIT(ksi);
  137         if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) {
  138                 if (WIFSIGNALED(p->p_xstat)) {
  139                         if (WCOREDUMP(p->p_xstat))
  140                                 ksi->ksi_code = CLD_DUMPED;
  141                         else
  142                                 ksi->ksi_code = CLD_KILLED;
  143                 } else {
  144                         ksi->ksi_code = CLD_EXITED;
  145                 }
  146         }
  147         /*
  148          * We fill those in, even for non-SIGCHLD.
  149          * It's safe to access p->p_cred unlocked here.
  150          */
  151         ksi->ksi_pid = p->p_pid;
  152         ksi->ksi_uid = kauth_cred_geteuid(p->p_cred);
  153         ksi->ksi_status = p->p_xstat;
  154         /* XXX: is this still valid? */
  155         ksi->ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec;
  156         ksi->ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec;
  157 }
  158 
  159 /*
  160  * exit --
  161  *      Death of process.
  162  */
  163 int
  164 sys_exit(struct lwp *l, const struct sys_exit_args *uap, register_t *retval)
  165 {
  166         /* {
  167                 syscallarg(int) rval;
  168         } */
  169         struct proc *p = l->l_proc;
  170 
  171         /* Don't call exit1() multiple times in the same process. */
  172         mutex_enter(p->p_lock);
  173         if (p->p_sflag & PS_WEXIT) {
  174                 mutex_exit(p->p_lock);
  175                 lwp_exit(l);
  176         }
  177 
  178         /* exit1() will release the mutex. */
  179         exit1(l, W_EXITCODE(SCARG(uap, rval), 0));
  180         /* NOTREACHED */
  181         return (0);
  182 }
  183 
  184 /*
  185  * Exit: deallocate address space and other resources, change proc state
  186  * to zombie, and unlink proc from allproc and parent's lists.  Save exit
  187  * status and rusage for wait().  Check for child processes and orphan them.
  188  *
  189  * Must be called with p->p_lock held.  Does not return.
  190  */
  191 void
  192 exit1(struct lwp *l, int rv)
  193 {
  194         struct proc     *p, *q, *nq;
  195         struct pgrp     *pgrp;
  196         ksiginfo_t      ksi;
  197         ksiginfoq_t     kq;
  198         int             wakeinit, sa;
  199 
  200         p = l->l_proc;
  201 
  202         KASSERT(mutex_owned(p->p_lock));
  203 
  204         if (__predict_false(p == initproc))
  205                 panic("init died (signal %d, exit %d)",
  206                     WTERMSIG(rv), WEXITSTATUS(rv));
  207 
  208         /*
  209          * Disable scheduler activation upcalls.  We're trying to get out of
  210          * here.
  211          */
  212         sa = 0;
  213 #ifdef KERN_SA
  214         if ((p->p_sa != NULL)) {
  215                 l->l_pflag |= LP_SA_NOBLOCK;
  216                 sa = 1;
  217         }
  218 #endif
  219 
  220         p->p_sflag |= PS_WEXIT;
  221 
  222         /*
  223          * Force all other LWPs to exit before we do.  Only then can we
  224          * begin to tear down the rest of the process state.
  225          */
  226         if (sa || p->p_nlwps > 1)
  227                 exit_lwps(l);
  228 
  229         ksiginfo_queue_init(&kq);
  230 
  231         /*
  232          * If we have been asked to stop on exit, do so now.
  233          */
  234         if (__predict_false(p->p_sflag & PS_STOPEXIT)) {
  235                 KERNEL_UNLOCK_ALL(l, &l->l_biglocks);
  236                 sigclearall(p, &contsigmask, &kq);
  237                 p->p_waited = 0;
  238                 membar_producer();
  239                 p->p_stat = SSTOP;
  240                 lwp_lock(l);
  241                 p->p_nrlwps--;
  242                 l->l_stat = LSSTOP;
  243                 mutex_exit(p->p_lock);
  244                 mi_switch(l);
  245                 KERNEL_LOCK(l->l_biglocks, l);
  246                 mutex_enter(p->p_lock);
  247         }
  248 
  249         /*
  250          * Bin any remaining signals and mark the process as dying so it will
  251          * not be found for, e.g. signals. 
  252          */
  253         sigfillset(&p->p_sigctx.ps_sigignore);
  254         sigclearall(p, NULL, &kq);
  255         p->p_stat = SDYING;
  256         mutex_exit(p->p_lock);
  257         ksiginfo_queue_drain(&kq);
  258 
  259         /* Destroy any lwpctl info. */
  260         if (p->p_lwpctl != NULL)
  261                 lwp_ctl_exit();
  262 
  263         /* Destroy all AIO works */
  264         aio_exit(p, p->p_aio);
  265 
  266         /*
  267          * Drain all remaining references that procfs, ptrace and others may
  268          * have on the process.
  269          */
  270         rw_enter(&p->p_reflock, RW_WRITER);
  271 
  272         DPRINTF(("exit1: %d.%d exiting.\n", p->p_pid, l->l_lid));
  273 
  274         timers_free(p, TIMERS_ALL);
  275 #if defined(__HAVE_RAS)
  276         ras_purgeall();
  277 #endif
  278 
  279         /*
  280          * Close open files, release open-file table and free signal
  281          * actions.  This may block!
  282          */
  283         fd_free();
  284         cwdfree(p->p_cwdi);
  285         p->p_cwdi = NULL;
  286         doexithooks(p);
  287         sigactsfree(p->p_sigacts);
  288 
  289         /*
  290          * Write out accounting data.
  291          */
  292         (void)acct_process(l);
  293 
  294 #ifdef KTRACE
  295         /*
  296          * Release trace file.
  297          */
  298         if (p->p_tracep != NULL) {
  299                 mutex_enter(&ktrace_lock);
  300                 ktrderef(p);
  301                 mutex_exit(&ktrace_lock);
  302         }
  303 #endif
  304 
  305         /*
  306          * If emulation has process exit hook, call it now.
  307          * Set the exit status now so that the exit hook has
  308          * an opportunity to tweak it (COMPAT_LINUX requires
  309          * this for thread group emulation)
  310          */
  311         p->p_xstat = rv;
  312         if (p->p_emul->e_proc_exit)
  313                 (*p->p_emul->e_proc_exit)(p);
  314 
  315         /*
  316          * Free the VM resources we're still holding on to.
  317          * We must do this from a valid thread because doing
  318          * so may block. This frees vmspace, which we don't
  319          * need anymore. The only remaining lwp is the one
  320          * we run at this moment, nothing runs in userland
  321          * anymore.
  322          */
  323         uvm_proc_exit(p);
  324 
  325         /*
  326          * Stop profiling.
  327          */
  328         if (__predict_false((p->p_stflag & PST_PROFIL) != 0)) {
  329                 mutex_spin_enter(&p->p_stmutex);
  330                 stopprofclock(p);
  331                 mutex_spin_exit(&p->p_stmutex);
  332         }
  333 
  334         /*
  335          * If parent is waiting for us to exit or exec, PL_PPWAIT is set; we
  336          * wake up the parent early to avoid deadlock.  We can do this once
  337          * the VM resources are released.
  338          */
  339         mutex_enter(proc_lock);
  340         if (p->p_lflag & PL_PPWAIT) {
  341                 p->p_lflag &= ~PL_PPWAIT;
  342                 cv_broadcast(&p->p_pptr->p_waitcv);
  343         }
  344 
  345         if (SESS_LEADER(p)) {
  346                 struct vnode *vprele = NULL, *vprevoke = NULL;
  347                 struct session *sp = p->p_session;
  348                 struct tty *tp;
  349 
  350                 if (sp->s_ttyvp) {
  351                         /*
  352                          * Controlling process.
  353                          * Signal foreground pgrp,
  354                          * drain controlling terminal
  355                          * and revoke access to controlling terminal.
  356                          */
  357                         tp = sp->s_ttyp;
  358                         mutex_spin_enter(&tty_lock);
  359                         if (tp->t_session == sp) {
  360                                 /* we can't guarantee the revoke will do this */
  361                                 pgrp = tp->t_pgrp;
  362                                 tp->t_pgrp = NULL;
  363                                 tp->t_session = NULL;
  364                                 mutex_spin_exit(&tty_lock);
  365                                 if (pgrp != NULL) {
  366                                         pgsignal(pgrp, SIGHUP, 1);
  367                                 }
  368                                 mutex_exit(proc_lock);
  369                                 (void) ttywait(tp);
  370                                 mutex_enter(proc_lock);
  371 
  372                                 /* The tty could have been revoked. */
  373                                 vprevoke = sp->s_ttyvp;
  374                         } else
  375                                 mutex_spin_exit(&tty_lock);
  376                         vprele = sp->s_ttyvp;
  377                         sp->s_ttyvp = NULL;
  378                         /*
  379                          * s_ttyp is not zero'd; we use this to indicate
  380                          * that the session once had a controlling terminal.
  381                          * (for logging and informational purposes)
  382                          */
  383                 }
  384                 sp->s_leader = NULL;
  385 
  386                 if (vprevoke != NULL || vprele != NULL) {
  387                         if (vprevoke != NULL) {
  388                                 SESSRELE(sp);
  389                                 mutex_exit(proc_lock);
  390                                 VOP_REVOKE(vprevoke, REVOKEALL);
  391                         } else
  392                                 mutex_exit(proc_lock);
  393                         if (vprele != NULL)
  394                                 vrele(vprele);
  395                         mutex_enter(proc_lock);
  396                 }
  397         }
  398         fixjobc(p, p->p_pgrp, 0);
  399 
  400         /*
  401          * Finalize the last LWP's specificdata, as well as the
  402          * specificdata for the proc itself.
  403          */
  404         lwp_finispecific(l);
  405         proc_finispecific(p);
  406 
  407         /*
  408          * Notify interested parties of our demise.
  409          */
  410         KNOTE(&p->p_klist, NOTE_EXIT);
  411 
  412 #if PERFCTRS
  413         /*
  414          * Save final PMC information in parent process & clean up.
  415          */
  416         if (PMC_ENABLED(p)) {
  417                 pmc_save_context(p);
  418                 pmc_accumulate(p->p_pptr, p);
  419                 pmc_process_exit(p);
  420         }
  421 #endif
  422 
  423         /*
  424          * Reset p_opptr pointer of all former children which got
  425          * traced by another process and were reparented. We reset
  426          * it to NULL here; the trace detach code then reparents
  427          * the child to initproc. We only check allproc list, since
  428          * eventual former children on zombproc list won't reference
  429          * p_opptr anymore.
  430          */
  431         if (__predict_false(p->p_slflag & PSL_CHTRACED)) {
  432                 PROCLIST_FOREACH(q, &allproc) {
  433                         if ((q->p_flag & PK_MARKER) != 0)
  434                                 continue;
  435                         if (q->p_opptr == p)
  436                                 q->p_opptr = NULL;
  437                 }
  438         }
  439 
  440         /*
  441          * Give orphaned children to init(8).
  442          */
  443         q = LIST_FIRST(&p->p_children);
  444         wakeinit = (q != NULL);
  445         for (; q != NULL; q = nq) {
  446                 nq = LIST_NEXT(q, p_sibling);
  447 
  448                 /*
  449                  * Traced processes are killed since their existence
  450                  * means someone is screwing up. Since we reset the
  451                  * trace flags, the logic in sys_wait4() would not be
  452                  * triggered to reparent the process to its
  453                  * original parent, so we must do this here.
  454                  */
  455                 if (__predict_false(q->p_slflag & PSL_TRACED)) {
  456                         mutex_enter(p->p_lock);
  457                         q->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL);
  458                         mutex_exit(p->p_lock);
  459                         if (q->p_opptr != q->p_pptr) {
  460                                 struct proc *t = q->p_opptr;
  461                                 proc_reparent(q, t ? t : initproc);
  462                                 q->p_opptr = NULL;
  463                         } else
  464                                 proc_reparent(q, initproc);
  465                         killproc(q, "orphaned traced process");
  466                 } else
  467                         proc_reparent(q, initproc);
  468         }
  469 
  470         /*
  471          * Move proc from allproc to zombproc, it's now nearly ready to be
  472          * collected by parent.
  473          */
  474         LIST_REMOVE(l, l_list);
  475         LIST_REMOVE(p, p_list);
  476         LIST_INSERT_HEAD(&zombproc, p, p_list);
  477 
  478         /*
  479          * Mark the process as dead.  We must do this before we signal
  480          * the parent.
  481          */
  482         p->p_stat = SDEAD;
  483 
  484         /* Put in front of parent's sibling list for parent to collect it */
  485         q = p->p_pptr;
  486         q->p_nstopchild++;
  487         if (LIST_FIRST(&q->p_children) != p) {
  488                 /* Put child where it can be found quickly */
  489                 LIST_REMOVE(p, p_sibling);
  490                 LIST_INSERT_HEAD(&q->p_children, p, p_sibling);
  491         }
  492 
  493         /*
  494          * Notify parent that we're gone.  If parent has the P_NOCLDWAIT
  495          * flag set, notify init instead (and hope it will handle
  496          * this situation).
  497          */
  498         if (q->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) {
  499                 proc_reparent(p, initproc);
  500                 wakeinit = 1;
  501 
  502                 /*
  503                  * If this was the last child of our parent, notify
  504                  * parent, so in case he was wait(2)ing, he will
  505                  * continue.
  506                  */
  507                 if (LIST_FIRST(&q->p_children) == NULL)
  508                         cv_broadcast(&q->p_waitcv);
  509         }
  510 
  511         /* Reload parent pointer, since p may have been reparented above */
  512         q = p->p_pptr;
  513 
  514         if (__predict_false((p->p_slflag & PSL_FSTRACE) == 0 && p->p_exitsig != 0)) {
  515                 exit_psignal(p, q, &ksi);
  516                 kpsignal(q, &ksi, NULL);
  517         }
  518 
  519         /* Calculate the final rusage info.  */
  520         calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime,
  521             NULL, NULL);
  522 
  523         if (wakeinit)
  524                 cv_broadcast(&initproc->p_waitcv);
  525 
  526         callout_destroy(&l->l_timeout_ch);
  527 
  528         /*
  529          * Remaining lwp resources will be freed in lwp_exit2() once we've
  530          * switch to idle context; at that point, we will be marked as a
  531          * full blown zombie.
  532          */
  533         mutex_enter(p->p_lock);
  534         lwp_drainrefs(l);
  535         lwp_lock(l);
  536         l->l_prflag &= ~LPR_DETACHED;
  537         l->l_stat = LSZOMB;
  538         lwp_unlock(l);
  539         KASSERT(curlwp == l);
  540         KASSERT(p->p_nrlwps == 1);
  541         KASSERT(p->p_nlwps == 1);
  542         p->p_stat = SZOMB;
  543         p->p_nrlwps--;
  544         p->p_nzlwps++;
  545         p->p_ndlwps = 0;
  546         mutex_exit(p->p_lock);
  547 
  548         /*
  549          * Signal the parent to collect us, and drop the proclist lock.
  550          * Drop debugger/procfs lock; no new references can be gained.
  551          */
  552         cv_broadcast(&p->p_pptr->p_waitcv);
  553         rw_exit(&p->p_reflock);
  554         mutex_exit(proc_lock);
  555 
  556         /* Verify that we hold no locks other than the kernel lock. */
  557         LOCKDEBUG_BARRIER(&kernel_lock, 0);
  558 
  559         /*
  560          * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP!
  561          */
  562 
  563         /*
  564          * Give machine-dependent code a chance to free any MD LWP
  565          * resources.  This must be done before uvm_lwp_exit(), in
  566          * case these resources are in the PCB.
  567          */
  568 #ifndef __NO_CPU_LWP_FREE
  569         cpu_lwp_free(l, 1);
  570 #endif
  571         pmap_deactivate(l);
  572 
  573         /* This process no longer needs to hold the kernel lock. */
  574 #ifdef notyet
  575         /* XXXSMP hold in lwp_userret() */
  576         KERNEL_UNLOCK_LAST(l);
  577 #else
  578         KERNEL_UNLOCK_ALL(l, NULL);
  579 #endif
  580 
  581         lwp_exit_switchaway(l);
  582 }
  583 
  584 void
  585 exit_lwps(struct lwp *l)
  586 {
  587         struct proc *p;
  588         struct lwp *l2;
  589         int error;
  590         lwpid_t waited;
  591         int nlocks;
  592 
  593         KERNEL_UNLOCK_ALL(l, &nlocks);
  594 
  595         p = l->l_proc;
  596         KASSERT(mutex_owned(p->p_lock));
  597 
  598 #ifdef KERN_SA
  599         if (p->p_sa != NULL) {
  600                 struct sadata_vp *vp;
  601                 SLIST_FOREACH(vp, &p->p_sa->sa_vps, savp_next) {
  602                         /*
  603                          * Make SA-cached LWPs normal process interruptable
  604                          * so that the exit code can wake them. Locking
  605                          * savp_mutex locks all the lwps on this vp that
  606                          * we need to adjust.
  607                          */
  608                         mutex_enter(&vp->savp_mutex);
  609                         DPRINTF(("exit_lwps: Making cached LWPs of %d on "
  610                             "VP %d interruptable: ", p->p_pid, vp->savp_id));
  611                         TAILQ_FOREACH(l2, &vp->savp_lwpcache, l_sleepchain) {
  612                                 l2->l_flag |= LW_SINTR;
  613                                 DPRINTF(("%d ", l2->l_lid));
  614                         }
  615                         DPRINTF(("\n"));
  616 
  617                         DPRINTF(("exit_lwps: Making unblocking LWPs of %d on "
  618                             "VP %d interruptable: ", p->p_pid, vp->savp_id));
  619                         TAILQ_FOREACH(l2, &vp->savp_woken, l_sleepchain) {
  620                                 vp->savp_woken_count--;
  621                                 l2->l_flag |= LW_SINTR;
  622                                 DPRINTF(("%d ", l2->l_lid));
  623                         }
  624                         DPRINTF(("\n"));
  625                         mutex_exit(&vp->savp_mutex);
  626                 }
  627         }
  628 #endif
  629 
  630  retry:
  631         /*
  632          * Interrupt LWPs in interruptable sleep, unsuspend suspended
  633          * LWPs and then wait for everyone else to finish.
  634          */
  635         LIST_FOREACH(l2, &p->p_lwps, l_sibling) {
  636                 if (l2 == l)
  637                         continue;
  638                 lwp_lock(l2);
  639                 l2->l_flag &= ~LW_SA;
  640                 l2->l_flag |= LW_WEXIT;
  641                 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) ||
  642                     l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) {
  643                         /* setrunnable() will release the lock. */
  644                         setrunnable(l2);
  645                         DPRINTF(("exit_lwps: Made %d.%d runnable\n",
  646                             p->p_pid, l2->l_lid));
  647                         continue;
  648                 }
  649                 lwp_unlock(l2);
  650         }
  651         while (p->p_nlwps > 1) {
  652                 DPRINTF(("exit_lwps: waiting for %d LWPs (%d zombies)\n",
  653                     p->p_nlwps, p->p_nzlwps));
  654                 error = lwp_wait1(l, 0, &waited, LWPWAIT_EXITCONTROL);
  655                 if (p->p_nlwps == 1)
  656                         break;
  657                 if (error == EDEADLK) {
  658                         /*
  659                          * LWPs can get suspended/slept behind us.
  660                          * (eg. sa_setwoken)
  661                          * kick them again and retry.
  662                          */
  663                         goto retry;
  664                 }
  665                 if (error)
  666                         panic("exit_lwps: lwp_wait1 failed with error %d",
  667                             error);
  668                 DPRINTF(("exit_lwps: Got LWP %d from lwp_wait1()\n", waited));
  669         }
  670 
  671         KERNEL_LOCK(nlocks, l);
  672         KASSERT(p->p_nlwps == 1);
  673 }
  674 
  675 int
  676 do_sys_wait(struct lwp *l, int *pid, int *status, int options,
  677     struct rusage *ru, int *was_zombie)
  678 {
  679         struct proc     *child;
  680         int             error;
  681 
  682         mutex_enter(proc_lock);
  683         error = find_stopped_child(l->l_proc, *pid, options, &child, status);
  684 
  685         if (child == NULL) {
  686                 mutex_exit(proc_lock);
  687                 *pid = 0;
  688                 return error;
  689         }
  690 
  691         *pid = child->p_pid;
  692 
  693         if (child->p_stat == SZOMB) {
  694                 /* proc_free() will release the proc_lock. */
  695                 *was_zombie = 1;
  696                 if (options & WNOWAIT)
  697                         mutex_exit(proc_lock);
  698                 else {
  699                         proc_free(child, ru);
  700                 }
  701         } else {
  702                 /* Child state must have been SSTOP. */
  703                 *was_zombie = 0;
  704                 mutex_exit(proc_lock);
  705                 *status = W_STOPCODE(*status);
  706         }
  707 
  708         return 0;
  709 }
  710 
  711 int
  712 sys_wait4(struct lwp *l, const struct sys_wait4_args *uap, register_t *retval)
  713 {
  714         /* {
  715                 syscallarg(int)                 pid;
  716                 syscallarg(int *)               status;
  717                 syscallarg(int)                 options;
  718                 syscallarg(struct rusage *)     rusage;
  719         } */
  720         int             status, error;
  721         int             was_zombie;
  722         struct rusage   ru;
  723         int pid = SCARG(uap, pid);
  724 
  725         error = do_sys_wait(l, &pid, &status, SCARG(uap, options),
  726             SCARG(uap, rusage) != NULL ? &ru : NULL, &was_zombie);
  727 
  728         retval[0] = pid;
  729         if (pid == 0)
  730                 return error;
  731 
  732         if (SCARG(uap, rusage))
  733                 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru));
  734 
  735         if (error == 0 && SCARG(uap, status))
  736                 error = copyout(&status, SCARG(uap, status), sizeof(status));
  737 
  738         return error;
  739 }
  740 
  741 /*
  742  * Scan list of child processes for a child process that has stopped or
  743  * exited.  Used by sys_wait4 and 'compat' equivalents.
  744  *
  745  * Must be called with the proc_lock held, and may release while waiting.
  746  */
  747 static int
  748 find_stopped_child(struct proc *parent, pid_t pid, int options,
  749                    struct proc **child_p, int *status_p)
  750 {
  751         struct proc *child, *dead;
  752         int error;
  753 
  754         KASSERT(mutex_owned(proc_lock));
  755 
  756         if (options & ~(WUNTRACED|WNOHANG|WALTSIG|WALLSIG)
  757             && !(options & WOPTSCHECKED)) {
  758                 *child_p = NULL;
  759                 return EINVAL;
  760         }
  761 
  762         if (pid == 0 && !(options & WOPTSCHECKED))
  763                 pid = -parent->p_pgid;
  764 
  765         for (;;) {
  766                 error = ECHILD;
  767                 dead = NULL;
  768 
  769                 LIST_FOREACH(child, &parent->p_children, p_sibling) {
  770                         if (pid >= 0) {
  771                                 if (child->p_pid != pid) {
  772                                         child = p_find(pid, PFIND_ZOMBIE |
  773                                             PFIND_LOCKED);
  774                                         if (child == NULL ||
  775                                             child->p_pptr != parent) {
  776                                                 child = NULL;
  777                                                 break;
  778                                         }
  779                                 }
  780                         } else if (pid != WAIT_ANY && child->p_pgid != -pid) {
  781                                 /* Child not in correct pgrp */
  782                                 continue;
  783                         }
  784 
  785                         /*
  786                          * Wait for processes with p_exitsig != SIGCHLD
  787                          * processes only if WALTSIG is set; wait for
  788                          * processes with p_exitsig == SIGCHLD only
  789                          * if WALTSIG is clear.
  790                          */
  791                         if (((options & WALLSIG) == 0) &&
  792                             (options & WALTSIG ? child->p_exitsig == SIGCHLD
  793                                                 : P_EXITSIG(child) != SIGCHLD)){
  794                                 if (child->p_pid == pid) {
  795                                         child = NULL;
  796                                         break;
  797                                 }
  798                                 continue;
  799                         }
  800 
  801                         error = 0;
  802                         if ((options & WNOZOMBIE) == 0) {
  803                                 if (child->p_stat == SZOMB)
  804                                         break;
  805                                 if (child->p_stat == SDEAD) {
  806                                         /*
  807                                          * We may occasionally arrive here
  808                                          * after receiving a signal, but
  809                                          * immediatley before the child
  810                                          * process is zombified.  The wait
  811                                          * will be short, so avoid returning
  812                                          * to userspace.
  813                                          */
  814                                         dead = child;
  815                                 }
  816                         }
  817 
  818                         if (child->p_stat == SSTOP &&
  819                             child->p_waited == 0 &&
  820                             (child->p_slflag & PSL_TRACED ||
  821                             options & WUNTRACED)) {
  822                                 if ((options & WNOWAIT) == 0) {
  823                                         child->p_waited = 1;
  824                                         parent->p_nstopchild--;
  825                                 }
  826                                 break;
  827                         }
  828                         if (parent->p_nstopchild == 0 || child->p_pid == pid) {
  829                                 child = NULL;
  830                                 break;
  831                         }
  832                 }
  833 
  834                 if (child != NULL || error != 0 ||
  835                     ((options & WNOHANG) != 0 && dead == NULL)) {
  836                         if (child != NULL) {
  837                                 *status_p = child->p_xstat;
  838                         }
  839                         *child_p = child;
  840                         return error;
  841                 }
  842 
  843                 /*
  844                  * Wait for another child process to stop.
  845                  */
  846                 error = cv_wait_sig(&parent->p_waitcv, proc_lock);
  847 
  848                 if (error != 0) {
  849                         *child_p = NULL;
  850                         return error;
  851                 }
  852         }
  853 }
  854 
  855 /*
  856  * Free a process after parent has taken all the state info.  Must be called
  857  * with the proclist lock held, and will release before returning.
  858  *
  859  * *ru is returned to the caller, and must be freed by the caller.
  860  */
  861 static void
  862 proc_free(struct proc *p, struct rusage *ru)
  863 {
  864         struct proc *parent;
  865         struct lwp *l;
  866         ksiginfo_t ksi;
  867         kauth_cred_t cred1, cred2;
  868         uid_t uid;
  869 
  870         KASSERT(mutex_owned(proc_lock));
  871         KASSERT(p->p_nlwps == 1);
  872         KASSERT(p->p_nzlwps == 1);
  873         KASSERT(p->p_nrlwps == 0);
  874         KASSERT(p->p_stat == SZOMB);
  875 
  876         /*
  877          * If we got the child via ptrace(2) or procfs, and
  878          * the parent is different (meaning the process was
  879          * attached, rather than run as a child), then we need
  880          * to give it back to the old parent, and send the
  881          * parent the exit signal.  The rest of the cleanup
  882          * will be done when the old parent waits on the child.
  883          */
  884         if ((p->p_slflag & PSL_TRACED) != 0) {
  885                 parent = p->p_pptr;
  886                 if (p->p_opptr != parent){
  887                         mutex_enter(p->p_lock);
  888                         p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL);
  889                         mutex_exit(p->p_lock);
  890                         parent = p->p_opptr;
  891                         if (parent == NULL)
  892                                 parent = initproc;
  893                         proc_reparent(p, parent);
  894                         p->p_opptr = NULL;
  895                         if (p->p_exitsig != 0) {
  896                                 exit_psignal(p, parent, &ksi);
  897                                 kpsignal(parent, &ksi, NULL);
  898                         }
  899                         cv_broadcast(&parent->p_waitcv);
  900                         mutex_exit(proc_lock);
  901                         return;
  902                 }
  903         }
  904 
  905         /*
  906          * Finally finished with old proc entry.  Unlink it from its process
  907          * group.
  908          */
  909         leavepgrp(p);
  910 
  911         parent = p->p_pptr;
  912         sched_proc_exit(parent, p);
  913 
  914         /*
  915          * Add child times of exiting process onto its own times.
  916          * This cannot be done any earlier else it might get done twice.
  917          */
  918         l = LIST_FIRST(&p->p_lwps);
  919         p->p_stats->p_ru.ru_nvcsw += (l->l_ncsw - l->l_nivcsw);
  920         p->p_stats->p_ru.ru_nivcsw += l->l_nivcsw;
  921         ruadd(&p->p_stats->p_ru, &l->l_ru);
  922         ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru);
  923         ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru);
  924         if (ru != NULL)
  925                 *ru = p->p_stats->p_ru;
  926         p->p_xstat = 0;
  927 
  928         /* Release any SA state. */
  929 #ifdef KERN_SA
  930         if (p->p_sa)
  931                 sa_release(p);
  932 #endif
  933 
  934         /*
  935          * At this point we are going to start freeing the final resources. 
  936          * If anyone tries to access the proc structure after here they will
  937          * get a shock - bits are missing.  Attempt to make it hard!  We
  938          * don't bother with any further locking past this point.
  939          */
  940         p->p_stat = SIDL;               /* not even a zombie any more */
  941         LIST_REMOVE(p, p_list); /* off zombproc */
  942         parent = p->p_pptr;
  943         p->p_pptr->p_nstopchild--;
  944         LIST_REMOVE(p, p_sibling);
  945 
  946         /*
  947          * Let pid be reallocated.
  948          */
  949         proc_free_pid(p);
  950         mutex_exit(proc_lock);
  951 
  952         /*
  953          * Delay release until after lwp_free.
  954          */
  955         cred2 = l->l_cred;
  956 
  957         /*
  958          * Free the last LWP's resources.
  959          *
  960          * lwp_free ensures the LWP is no longer running on another CPU.
  961          */
  962         lwp_free(l, false, true);
  963 
  964         /*
  965          * Now no one except us can reach the process p.
  966          */
  967 
  968         /*
  969          * Decrement the count of procs running with this uid.
  970          */
  971         cred1 = p->p_cred;
  972         uid = kauth_cred_getuid(cred1);
  973         (void)chgproccnt(uid, -1);
  974 
  975         /*
  976          * Release substructures.
  977          */
  978 
  979         limfree(p->p_limit);
  980         pstatsfree(p->p_stats);
  981         kauth_cred_free(cred1);
  982         kauth_cred_free(cred2);
  983 
  984         /*
  985          * Release reference to text vnode
  986          */
  987         if (p->p_textvp)
  988                 vrele(p->p_textvp);
  989 
  990         mutex_destroy(&p->p_auxlock);
  991         mutex_obj_free(p->p_lock);
  992         mutex_destroy(&p->p_stmutex);
  993         cv_destroy(&p->p_waitcv);
  994         cv_destroy(&p->p_lwpcv);
  995         rw_destroy(&p->p_reflock);
  996 
  997         proc_free_mem(p);
  998 }
  999 
 1000 /*
 1001  * make process 'parent' the new parent of process 'child'.
 1002  *
 1003  * Must be called with proc_lock held.
 1004  */
 1005 void
 1006 proc_reparent(struct proc *child, struct proc *parent)
 1007 {
 1008 
 1009         KASSERT(mutex_owned(proc_lock));
 1010 
 1011         if (child->p_pptr == parent)
 1012                 return;
 1013 
 1014         if (child->p_stat == SZOMB ||
 1015             (child->p_stat == SSTOP && !child->p_waited)) {
 1016                 child->p_pptr->p_nstopchild--;
 1017                 parent->p_nstopchild++;
 1018         }
 1019         if (parent == initproc)
 1020                 child->p_exitsig = SIGCHLD;
 1021 
 1022         LIST_REMOVE(child, p_sibling);
 1023         LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
 1024         child->p_pptr = parent;
 1025         child->p_ppid = parent->p_pid;
 1026 }

Cache object: be2f23c32805e8abbab3c64c8ae5768e


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.