The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exit.c

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    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  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)kern_exit.c 8.7 (Berkeley) 2/12/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: releng/8.1/sys/kern/kern_exit.c 199583 2009-11-20 15:27:52Z jhb $");
   39 
   40 #include "opt_compat.h"
   41 #include "opt_kdtrace.h"
   42 #include "opt_ktrace.h"
   43 
   44 #include <sys/param.h>
   45 #include <sys/systm.h>
   46 #include <sys/sysproto.h>
   47 #include <sys/eventhandler.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/jail.h>
   55 #include <sys/tty.h>
   56 #include <sys/wait.h>
   57 #include <sys/vmmeter.h>
   58 #include <sys/vnode.h>
   59 #include <sys/resourcevar.h>
   60 #include <sys/sbuf.h>
   61 #include <sys/signalvar.h>
   62 #include <sys/sched.h>
   63 #include <sys/sx.h>
   64 #include <sys/syscallsubr.h>
   65 #include <sys/syslog.h>
   66 #include <sys/ptrace.h>
   67 #include <sys/acct.h>           /* for acct_process() function prototype */
   68 #include <sys/filedesc.h>
   69 #include <sys/sdt.h>
   70 #include <sys/shm.h>
   71 #include <sys/sem.h>
   72 #ifdef KTRACE
   73 #include <sys/ktrace.h>
   74 #endif
   75 
   76 #include <security/audit/audit.h>
   77 #include <security/mac/mac_framework.h>
   78 
   79 #include <vm/vm.h>
   80 #include <vm/vm_extern.h>
   81 #include <vm/vm_param.h>
   82 #include <vm/pmap.h>
   83 #include <vm/vm_map.h>
   84 #include <vm/vm_page.h>
   85 #include <vm/uma.h>
   86 
   87 #ifdef KDTRACE_HOOKS
   88 #include <sys/dtrace_bsd.h>
   89 dtrace_execexit_func_t  dtrace_fasttrap_exit;
   90 #endif
   91 
   92 SDT_PROVIDER_DECLARE(proc);
   93 SDT_PROBE_DEFINE(proc, kernel, , exit);
   94 SDT_PROBE_ARGTYPE(proc, kernel, , exit, 0, "int");
   95 
   96 /* Required to be non-static for SysVR4 emulator */
   97 MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
   98 
   99 /* Hook for NFS teardown procedure. */
  100 void (*nlminfo_release_p)(struct proc *p);
  101 
  102 /*
  103  * exit -- death of process.
  104  */
  105 void
  106 sys_exit(struct thread *td, struct sys_exit_args *uap)
  107 {
  108 
  109         exit1(td, W_EXITCODE(uap->rval, 0));
  110         /* NOTREACHED */
  111 }
  112 
  113 /*
  114  * Exit: deallocate address space and other resources, change proc state to
  115  * zombie, and unlink proc from allproc and parent's lists.  Save exit status
  116  * and rusage for wait().  Check for child processes and orphan them.
  117  */
  118 void
  119 exit1(struct thread *td, int rv)
  120 {
  121         struct proc *p, *nq, *q;
  122         struct vnode *vtmp;
  123         struct vnode *ttyvp = NULL;
  124 #ifdef KTRACE
  125         struct vnode *tracevp;
  126         struct ucred *tracecred;
  127 #endif
  128         struct plimit *plim;
  129         int locked;
  130 
  131         mtx_assert(&Giant, MA_NOTOWNED);
  132 
  133         p = td->td_proc;
  134         /*
  135          * XXX in case we're rebooting we just let init die in order to
  136          * work around an unsolved stack overflow seen very late during
  137          * shutdown on sparc64 when the gmirror worker process exists.
  138          */ 
  139         if (p == initproc && rebooting == 0) {
  140                 printf("init died (signal %d, exit %d)\n",
  141                     WTERMSIG(rv), WEXITSTATUS(rv));
  142                 panic("Going nowhere without my init!");
  143         }
  144 
  145         /*
  146          * MUST abort all other threads before proceeding past here.
  147          */
  148         PROC_LOCK(p);
  149         while (p->p_flag & P_HADTHREADS) {
  150                 /*
  151                  * First check if some other thread got here before us..
  152                  * if so, act apropriatly, (exit or suspend);
  153                  */
  154                 thread_suspend_check(0);
  155 
  156                 /*
  157                  * Kill off the other threads. This requires
  158                  * some co-operation from other parts of the kernel
  159                  * so it may not be instantaneous.  With this state set
  160                  * any thread entering the kernel from userspace will
  161                  * thread_exit() in trap().  Any thread attempting to
  162                  * sleep will return immediately with EINTR or EWOULDBLOCK
  163                  * which will hopefully force them to back out to userland
  164                  * freeing resources as they go.  Any thread attempting
  165                  * to return to userland will thread_exit() from userret().
  166                  * thread_exit() will unsuspend us when the last of the
  167                  * other threads exits.
  168                  * If there is already a thread singler after resumption,
  169                  * calling thread_single will fail; in that case, we just
  170                  * re-check all suspension request, the thread should
  171                  * either be suspended there or exit.
  172                  */
  173                 if (! thread_single(SINGLE_EXIT))
  174                         break;
  175 
  176                 /*
  177                  * All other activity in this process is now stopped.
  178                  * Threading support has been turned off.
  179                  */
  180         }
  181         KASSERT(p->p_numthreads == 1,
  182             ("exit1: proc %p exiting with %d threads", p, p->p_numthreads));
  183         /*
  184          * Wakeup anyone in procfs' PIOCWAIT.  They should have a hold
  185          * on our vmspace, so we should block below until they have
  186          * released their reference to us.  Note that if they have
  187          * requested S_EXIT stops we will block here until they ack
  188          * via PIOCCONT.
  189          */
  190         _STOPEVENT(p, S_EXIT, rv);
  191 
  192         /*
  193          * Note that we are exiting and do another wakeup of anyone in
  194          * PIOCWAIT in case they aren't listening for S_EXIT stops or
  195          * decided to wait again after we told them we are exiting.
  196          */
  197         p->p_flag |= P_WEXIT;
  198         wakeup(&p->p_stype);
  199 
  200         /*
  201          * Wait for any processes that have a hold on our vmspace to
  202          * release their reference.
  203          */
  204         while (p->p_lock > 0)
  205                 msleep(&p->p_lock, &p->p_mtx, PWAIT, "exithold", 0);
  206 
  207         PROC_UNLOCK(p);
  208         /* Drain the limit callout while we don't have the proc locked */
  209         callout_drain(&p->p_limco);
  210 
  211 #ifdef AUDIT
  212         /*
  213          * The Sun BSM exit token contains two components: an exit status as
  214          * passed to exit(), and a return value to indicate what sort of exit
  215          * it was.  The exit status is WEXITSTATUS(rv), but it's not clear
  216          * what the return value is.
  217          */
  218         AUDIT_ARG_EXIT(WEXITSTATUS(rv), 0);
  219         AUDIT_SYSCALL_EXIT(0, td);
  220 #endif
  221 
  222         /* Are we a task leader? */
  223         if (p == p->p_leader) {
  224                 mtx_lock(&ppeers_lock);
  225                 q = p->p_peers;
  226                 while (q != NULL) {
  227                         PROC_LOCK(q);
  228                         psignal(q, SIGKILL);
  229                         PROC_UNLOCK(q);
  230                         q = q->p_peers;
  231                 }
  232                 while (p->p_peers != NULL)
  233                         msleep(p, &ppeers_lock, PWAIT, "exit1", 0);
  234                 mtx_unlock(&ppeers_lock);
  235         }
  236 
  237         /*
  238          * Check if any loadable modules need anything done at process exit.
  239          * E.g. SYSV IPC stuff
  240          * XXX what if one of these generates an error?
  241          */
  242         EVENTHANDLER_INVOKE(process_exit, p);
  243 
  244         /*
  245          * If parent is waiting for us to exit or exec,
  246          * P_PPWAIT is set; we will wakeup the parent below.
  247          */
  248         PROC_LOCK(p);
  249         stopprofclock(p);
  250         p->p_flag &= ~(P_TRACED | P_PPWAIT);
  251 
  252         /*
  253          * Stop the real interval timer.  If the handler is currently
  254          * executing, prevent it from rearming itself and let it finish.
  255          */
  256         if (timevalisset(&p->p_realtimer.it_value) &&
  257             callout_stop(&p->p_itcallout) == 0) {
  258                 timevalclear(&p->p_realtimer.it_interval);
  259                 msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait", 0);
  260                 KASSERT(!timevalisset(&p->p_realtimer.it_value),
  261                     ("realtime timer is still armed"));
  262         }
  263         PROC_UNLOCK(p);
  264 
  265         /*
  266          * Reset any sigio structures pointing to us as a result of
  267          * F_SETOWN with our pid.
  268          */
  269         funsetownlst(&p->p_sigiolst);
  270 
  271         /*
  272          * If this process has an nlminfo data area (for lockd), release it
  273          */
  274         if (nlminfo_release_p != NULL && p->p_nlminfo != NULL)
  275                 (*nlminfo_release_p)(p);
  276 
  277         /*
  278          * Close open files and release open-file table.
  279          * This may block!
  280          */
  281         fdfree(td);
  282 
  283         /*
  284          * If this thread tickled GEOM, we need to wait for the giggling to
  285          * stop before we return to userland
  286          */
  287         if (td->td_pflags & TDP_GEOM)
  288                 g_waitidle();
  289 
  290         /*
  291          * Remove ourself from our leader's peer list and wake our leader.
  292          */
  293         mtx_lock(&ppeers_lock);
  294         if (p->p_leader->p_peers) {
  295                 q = p->p_leader;
  296                 while (q->p_peers != p)
  297                         q = q->p_peers;
  298                 q->p_peers = p->p_peers;
  299                 wakeup(p->p_leader);
  300         }
  301         mtx_unlock(&ppeers_lock);
  302 
  303         vmspace_exit(td);
  304 
  305         sx_xlock(&proctree_lock);
  306         if (SESS_LEADER(p)) {
  307                 struct session *sp = p->p_session;
  308                 struct tty *tp;
  309 
  310                 /*
  311                  * s_ttyp is not zero'd; we use this to indicate that
  312                  * the session once had a controlling terminal. (for
  313                  * logging and informational purposes)
  314                  */
  315                 SESS_LOCK(sp);
  316                 ttyvp = sp->s_ttyvp;
  317                 tp = sp->s_ttyp;
  318                 sp->s_ttyvp = NULL;
  319                 sp->s_leader = NULL;
  320                 SESS_UNLOCK(sp);
  321 
  322                 /*
  323                  * Signal foreground pgrp and revoke access to
  324                  * controlling terminal if it has not been revoked
  325                  * already.
  326                  *
  327                  * Because the TTY may have been revoked in the mean
  328                  * time and could already have a new session associated
  329                  * with it, make sure we don't send a SIGHUP to a
  330                  * foreground process group that does not belong to this
  331                  * session.
  332                  */
  333 
  334                 if (tp != NULL) {
  335                         tty_lock(tp);
  336                         if (tp->t_session == sp)
  337                                 tty_signal_pgrp(tp, SIGHUP);
  338                         tty_unlock(tp);
  339                 }
  340 
  341                 if (ttyvp != NULL) {
  342                         sx_xunlock(&proctree_lock);
  343                         if (vn_lock(ttyvp, LK_EXCLUSIVE) == 0) {
  344                                 VOP_REVOKE(ttyvp, REVOKEALL);
  345                                 VOP_UNLOCK(ttyvp, 0);
  346                         }
  347                         sx_xlock(&proctree_lock);
  348                 }
  349         }
  350         fixjobc(p, p->p_pgrp, 0);
  351         sx_xunlock(&proctree_lock);
  352         (void)acct_process(td);
  353 
  354         /* Release the TTY now we've unlocked everything. */
  355         if (ttyvp != NULL)
  356                 vrele(ttyvp);
  357 #ifdef KTRACE
  358         /*
  359          * Disable tracing, then drain any pending records and release
  360          * the trace file.
  361          */
  362         if (p->p_traceflag != 0) {
  363                 PROC_LOCK(p);
  364                 mtx_lock(&ktrace_mtx);
  365                 p->p_traceflag = 0;
  366                 mtx_unlock(&ktrace_mtx);
  367                 PROC_UNLOCK(p);
  368                 ktrprocexit(td);
  369                 PROC_LOCK(p);
  370                 mtx_lock(&ktrace_mtx);
  371                 tracevp = p->p_tracevp;
  372                 p->p_tracevp = NULL;
  373                 tracecred = p->p_tracecred;
  374                 p->p_tracecred = NULL;
  375                 mtx_unlock(&ktrace_mtx);
  376                 PROC_UNLOCK(p);
  377                 if (tracevp != NULL) {
  378                         locked = VFS_LOCK_GIANT(tracevp->v_mount);
  379                         vrele(tracevp);
  380                         VFS_UNLOCK_GIANT(locked);
  381                 }
  382                 if (tracecred != NULL)
  383                         crfree(tracecred);
  384         }
  385 #endif
  386         /*
  387          * Release reference to text vnode
  388          */
  389         if ((vtmp = p->p_textvp) != NULL) {
  390                 p->p_textvp = NULL;
  391                 locked = VFS_LOCK_GIANT(vtmp->v_mount);
  392                 vrele(vtmp);
  393                 VFS_UNLOCK_GIANT(locked);
  394         }
  395 
  396         /*
  397          * Release our limits structure.
  398          */
  399         PROC_LOCK(p);
  400         plim = p->p_limit;
  401         p->p_limit = NULL;
  402         PROC_UNLOCK(p);
  403         lim_free(plim);
  404 
  405         /*
  406          * Remove proc from allproc queue and pidhash chain.
  407          * Place onto zombproc.  Unlink from parent's child list.
  408          */
  409         sx_xlock(&allproc_lock);
  410         LIST_REMOVE(p, p_list);
  411         LIST_INSERT_HEAD(&zombproc, p, p_list);
  412         LIST_REMOVE(p, p_hash);
  413         sx_xunlock(&allproc_lock);
  414 
  415         /*
  416          * Call machine-dependent code to release any
  417          * machine-dependent resources other than the address space.
  418          * The address space is released by "vmspace_exitfree(p)" in
  419          * vm_waitproc().
  420          */
  421         cpu_exit(td);
  422 
  423         WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid);
  424 
  425         /*
  426          * Reparent all of our children to init.
  427          */
  428         sx_xlock(&proctree_lock);
  429         q = LIST_FIRST(&p->p_children);
  430         if (q != NULL)          /* only need this if any child is S_ZOMB */
  431                 wakeup(initproc);
  432         for (; q != NULL; q = nq) {
  433                 nq = LIST_NEXT(q, p_sibling);
  434                 PROC_LOCK(q);
  435                 proc_reparent(q, initproc);
  436                 q->p_sigparent = SIGCHLD;
  437                 /*
  438                  * Traced processes are killed
  439                  * since their existence means someone is screwing up.
  440                  */
  441                 if (q->p_flag & P_TRACED) {
  442                         struct thread *temp;
  443 
  444                         q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE);
  445                         FOREACH_THREAD_IN_PROC(q, temp)
  446                                 temp->td_dbgflags &= ~TDB_SUSPEND;
  447                         psignal(q, SIGKILL);
  448                 }
  449                 PROC_UNLOCK(q);
  450         }
  451 
  452         /* Save exit status. */
  453         PROC_LOCK(p);
  454         p->p_xstat = rv;
  455         p->p_xthread = td;
  456 
  457         /* Tell the prison that we are gone. */
  458         prison_proc_free(p->p_ucred->cr_prison);
  459 
  460 #ifdef KDTRACE_HOOKS
  461         /*
  462          * Tell the DTrace fasttrap provider about the exit if it
  463          * has declared an interest.
  464          */
  465         if (dtrace_fasttrap_exit)
  466                 dtrace_fasttrap_exit(p);
  467 #endif
  468 
  469         /*
  470          * Notify interested parties of our demise.
  471          */
  472         KNOTE_LOCKED(&p->p_klist, NOTE_EXIT);
  473 
  474 #ifdef KDTRACE_HOOKS
  475         int reason = CLD_EXITED;
  476         if (WCOREDUMP(rv))
  477                 reason = CLD_DUMPED;
  478         else if (WIFSIGNALED(rv))
  479                 reason = CLD_KILLED;
  480         SDT_PROBE(proc, kernel, , exit, reason, 0, 0, 0, 0);
  481 #endif
  482 
  483         /*
  484          * Just delete all entries in the p_klist. At this point we won't
  485          * report any more events, and there are nasty race conditions that
  486          * can beat us if we don't.
  487          */
  488         knlist_clear(&p->p_klist, 1);
  489 
  490         /*
  491          * Notify parent that we're gone.  If parent has the PS_NOCLDWAIT
  492          * flag set, or if the handler is set to SIG_IGN, notify process
  493          * 1 instead (and hope it will handle this situation).
  494          */
  495         PROC_LOCK(p->p_pptr);
  496         mtx_lock(&p->p_pptr->p_sigacts->ps_mtx);
  497         if (p->p_pptr->p_sigacts->ps_flag & (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
  498                 struct proc *pp;
  499 
  500                 mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
  501                 pp = p->p_pptr;
  502                 PROC_UNLOCK(pp);
  503                 proc_reparent(p, initproc);
  504                 p->p_sigparent = SIGCHLD;
  505                 PROC_LOCK(p->p_pptr);
  506 
  507                 /*
  508                  * Notify parent, so in case he was wait(2)ing or
  509                  * executing waitpid(2) with our pid, he will
  510                  * continue.
  511                  */
  512                 wakeup(pp);
  513         } else
  514                 mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
  515 
  516         if (p->p_pptr == initproc)
  517                 psignal(p->p_pptr, SIGCHLD);
  518         else if (p->p_sigparent != 0) {
  519                 if (p->p_sigparent == SIGCHLD)
  520                         childproc_exited(p);
  521                 else    /* LINUX thread */
  522                         psignal(p->p_pptr, p->p_sigparent);
  523         }
  524         sx_xunlock(&proctree_lock);
  525 
  526         /*
  527          * The state PRS_ZOMBIE prevents other proesses from sending
  528          * signal to the process, to avoid memory leak, we free memory
  529          * for signal queue at the time when the state is set.
  530          */
  531         sigqueue_flush(&p->p_sigqueue);
  532         sigqueue_flush(&td->td_sigqueue);
  533 
  534         /*
  535          * We have to wait until after acquiring all locks before
  536          * changing p_state.  We need to avoid all possible context
  537          * switches (including ones from blocking on a mutex) while
  538          * marked as a zombie.  We also have to set the zombie state
  539          * before we release the parent process' proc lock to avoid
  540          * a lost wakeup.  So, we first call wakeup, then we grab the
  541          * sched lock, update the state, and release the parent process'
  542          * proc lock.
  543          */
  544         wakeup(p->p_pptr);
  545         cv_broadcast(&p->p_pwait);
  546         sched_exit(p->p_pptr, td);
  547         PROC_SLOCK(p);
  548         p->p_state = PRS_ZOMBIE;
  549         PROC_UNLOCK(p->p_pptr);
  550 
  551         /*
  552          * Hopefully no one will try to deliver a signal to the process this
  553          * late in the game.
  554          */
  555         knlist_destroy(&p->p_klist);
  556 
  557         /*
  558          * Save our children's rusage information in our exit rusage.
  559          */
  560         ruadd(&p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
  561 
  562         /*
  563          * Make sure the scheduler takes this thread out of its tables etc.
  564          * This will also release this thread's reference to the ucred.
  565          * Other thread parts to release include pcb bits and such.
  566          */
  567         thread_exit();
  568 }
  569 
  570 
  571 #ifndef _SYS_SYSPROTO_H_
  572 struct abort2_args {
  573         char *why;
  574         int nargs;
  575         void **args;
  576 };
  577 #endif
  578 
  579 int
  580 abort2(struct thread *td, struct abort2_args *uap)
  581 {
  582         struct proc *p = td->td_proc;
  583         struct sbuf *sb;
  584         void *uargs[16];
  585         int error, i, sig;
  586 
  587         /*
  588          * Do it right now so we can log either proper call of abort2(), or
  589          * note, that invalid argument was passed. 512 is big enough to
  590          * handle 16 arguments' descriptions with additional comments.
  591          */
  592         sb = sbuf_new(NULL, NULL, 512, SBUF_FIXEDLEN);
  593         sbuf_clear(sb);
  594         sbuf_printf(sb, "%s(pid %d uid %d) aborted: ",
  595             p->p_comm, p->p_pid, td->td_ucred->cr_uid);
  596         /* 
  597          * Since we can't return from abort2(), send SIGKILL in cases, where
  598          * abort2() was called improperly
  599          */
  600         sig = SIGKILL;
  601         /* Prevent from DoSes from user-space. */
  602         if (uap->nargs < 0 || uap->nargs > 16)
  603                 goto out;
  604         if (uap->nargs > 0) {
  605                 if (uap->args == NULL)
  606                         goto out;
  607                 error = copyin(uap->args, uargs, uap->nargs * sizeof(void *));
  608                 if (error != 0)
  609                         goto out;
  610         }
  611         /*
  612          * Limit size of 'reason' string to 128. Will fit even when
  613          * maximal number of arguments was chosen to be logged.
  614          */
  615         if (uap->why != NULL) {
  616                 error = sbuf_copyin(sb, uap->why, 128);
  617                 if (error < 0)
  618                         goto out;
  619         } else {
  620                 sbuf_printf(sb, "(null)");
  621         }
  622         if (uap->nargs > 0) {
  623                 sbuf_printf(sb, "(");
  624                 for (i = 0;i < uap->nargs; i++)
  625                         sbuf_printf(sb, "%s%p", i == 0 ? "" : ", ", uargs[i]);
  626                 sbuf_printf(sb, ")");
  627         }
  628         /*
  629          * Final stage: arguments were proper, string has been
  630          * successfully copied from userspace, and copying pointers
  631          * from user-space succeed.
  632          */
  633         sig = SIGABRT;
  634 out:
  635         if (sig == SIGKILL) {
  636                 sbuf_trim(sb);
  637                 sbuf_printf(sb, " (Reason text inaccessible)");
  638         }
  639         sbuf_cat(sb, "\n");
  640         sbuf_finish(sb);
  641         log(LOG_INFO, "%s", sbuf_data(sb));
  642         sbuf_delete(sb);
  643         exit1(td, W_EXITCODE(0, sig));
  644         return (0);
  645 }
  646 
  647 
  648 #ifdef COMPAT_43
  649 /*
  650  * The dirty work is handled by kern_wait().
  651  */
  652 int
  653 owait(struct thread *td, struct owait_args *uap __unused)
  654 {
  655         int error, status;
  656 
  657         error = kern_wait(td, WAIT_ANY, &status, 0, NULL);
  658         if (error == 0)
  659                 td->td_retval[1] = status;
  660         return (error);
  661 }
  662 #endif /* COMPAT_43 */
  663 
  664 /*
  665  * The dirty work is handled by kern_wait().
  666  */
  667 int
  668 wait4(struct thread *td, struct wait_args *uap)
  669 {
  670         struct rusage ru, *rup;
  671         int error, status;
  672 
  673         if (uap->rusage != NULL)
  674                 rup = &ru;
  675         else
  676                 rup = NULL;
  677         error = kern_wait(td, uap->pid, &status, uap->options, rup);
  678         if (uap->status != NULL && error == 0)
  679                 error = copyout(&status, uap->status, sizeof(status));
  680         if (uap->rusage != NULL && error == 0)
  681                 error = copyout(&ru, uap->rusage, sizeof(struct rusage));
  682         return (error);
  683 }
  684 
  685 /*
  686  * Reap the remains of a zombie process and optionally return status and
  687  * rusage.  Asserts and will release both the proctree_lock and the process
  688  * lock as part of its work.
  689  */
  690 static void
  691 proc_reap(struct thread *td, struct proc *p, int *status, int options,
  692     struct rusage *rusage)
  693 {
  694         struct proc *q, *t;
  695 
  696         sx_assert(&proctree_lock, SA_XLOCKED);
  697         PROC_LOCK_ASSERT(p, MA_OWNED);
  698         PROC_SLOCK_ASSERT(p, MA_OWNED);
  699         KASSERT(p->p_state == PRS_ZOMBIE, ("proc_reap: !PRS_ZOMBIE"));
  700 
  701         q = td->td_proc;
  702         if (rusage) {
  703                 *rusage = p->p_ru;
  704                 calcru(p, &rusage->ru_utime, &rusage->ru_stime);
  705         }
  706         PROC_SUNLOCK(p);
  707         td->td_retval[0] = p->p_pid;
  708         if (status)
  709                 *status = p->p_xstat;   /* convert to int */
  710         if (options & WNOWAIT) {
  711                 /*
  712                  *  Only poll, returning the status.  Caller does not wish to
  713                  * release the proc struct just yet.
  714                  */
  715                 PROC_UNLOCK(p);
  716                 sx_xunlock(&proctree_lock);
  717                 return;
  718         }
  719 
  720         PROC_LOCK(q);
  721         sigqueue_take(p->p_ksi);
  722         PROC_UNLOCK(q);
  723         PROC_UNLOCK(p);
  724 
  725         /*
  726          * If we got the child via a ptrace 'attach', we need to give it back
  727          * to the old parent.
  728          */
  729         if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
  730                 PROC_LOCK(p);
  731                 p->p_oppid = 0;
  732                 proc_reparent(p, t);
  733                 PROC_UNLOCK(p);
  734                 tdsignal(t, NULL, SIGCHLD, p->p_ksi);
  735                 wakeup(t);
  736                 cv_broadcast(&p->p_pwait);
  737                 PROC_UNLOCK(t);
  738                 sx_xunlock(&proctree_lock);
  739                 return;
  740         }
  741 
  742         /*
  743          * Remove other references to this process to ensure we have an
  744          * exclusive reference.
  745          */
  746         sx_xlock(&allproc_lock);
  747         LIST_REMOVE(p, p_list); /* off zombproc */
  748         sx_xunlock(&allproc_lock);
  749         LIST_REMOVE(p, p_sibling);
  750         leavepgrp(p);
  751         sx_xunlock(&proctree_lock);
  752 
  753         /*
  754          * As a side effect of this lock, we know that all other writes to
  755          * this proc are visible now, so no more locking is needed for p.
  756          */
  757         PROC_LOCK(p);
  758         p->p_xstat = 0;         /* XXX: why? */
  759         PROC_UNLOCK(p);
  760         PROC_LOCK(q);
  761         ruadd(&q->p_stats->p_cru, &q->p_crux, &p->p_ru, &p->p_rux);
  762         PROC_UNLOCK(q);
  763 
  764         /*
  765          * Decrement the count of procs running with this uid.
  766          */
  767         (void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
  768 
  769         /*
  770          * Free credentials, arguments, and sigacts.
  771          */
  772         crfree(p->p_ucred);
  773         p->p_ucred = NULL;
  774         pargs_drop(p->p_args);
  775         p->p_args = NULL;
  776         sigacts_free(p->p_sigacts);
  777         p->p_sigacts = NULL;
  778 
  779         /*
  780          * Do any thread-system specific cleanups.
  781          */
  782         thread_wait(p);
  783 
  784         /*
  785          * Give vm and machine-dependent layer a chance to free anything that
  786          * cpu_exit couldn't release while still running in process context.
  787          */
  788         vm_waitproc(p);
  789 #ifdef MAC
  790         mac_proc_destroy(p);
  791 #endif
  792         KASSERT(FIRST_THREAD_IN_PROC(p),
  793             ("proc_reap: no residual thread!"));
  794         uma_zfree(proc_zone, p);
  795         sx_xlock(&allproc_lock);
  796         nprocs--;
  797         sx_xunlock(&allproc_lock);
  798 }
  799 
  800 int
  801 kern_wait(struct thread *td, pid_t pid, int *status, int options,
  802     struct rusage *rusage)
  803 {
  804         struct proc *p, *q;
  805         int error, nfound;
  806 
  807         AUDIT_ARG_PID(pid);
  808         AUDIT_ARG_VALUE(options);
  809 
  810         q = td->td_proc;
  811         if (pid == 0) {
  812                 PROC_LOCK(q);
  813                 pid = -q->p_pgid;
  814                 PROC_UNLOCK(q);
  815         }
  816         if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WNOWAIT|WLINUXCLONE))
  817                 return (EINVAL);
  818 loop:
  819         if (q->p_flag & P_STATCHILD) {
  820                 PROC_LOCK(q);
  821                 q->p_flag &= ~P_STATCHILD;
  822                 PROC_UNLOCK(q);
  823         }
  824         nfound = 0;
  825         sx_xlock(&proctree_lock);
  826         LIST_FOREACH(p, &q->p_children, p_sibling) {
  827                 PROC_LOCK(p);
  828                 if (pid != WAIT_ANY &&
  829                     p->p_pid != pid && p->p_pgid != -pid) {
  830                         PROC_UNLOCK(p);
  831                         continue;
  832                 }
  833                 if (p_canwait(td, p)) {
  834                         PROC_UNLOCK(p);
  835                         continue;
  836                 }
  837 
  838                 /*
  839                  * This special case handles a kthread spawned by linux_clone
  840                  * (see linux_misc.c).  The linux_wait4 and linux_waitpid
  841                  * functions need to be able to distinguish between waiting
  842                  * on a process and waiting on a thread.  It is a thread if
  843                  * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
  844                  * signifies we want to wait for threads and not processes.
  845                  */
  846                 if ((p->p_sigparent != SIGCHLD) ^
  847                     ((options & WLINUXCLONE) != 0)) {
  848                         PROC_UNLOCK(p);
  849                         continue;
  850                 }
  851 
  852                 nfound++;
  853                 PROC_SLOCK(p);
  854                 if (p->p_state == PRS_ZOMBIE) {
  855                         proc_reap(td, p, status, options, rusage);
  856                         return (0);
  857                 }
  858                 if ((p->p_flag & P_STOPPED_SIG) &&
  859                     (p->p_suspcount == p->p_numthreads) &&
  860                     (p->p_flag & P_WAITED) == 0 &&
  861                     (p->p_flag & P_TRACED || options & WUNTRACED)) {
  862                         PROC_SUNLOCK(p);
  863                         p->p_flag |= P_WAITED;
  864                         sx_xunlock(&proctree_lock);
  865                         td->td_retval[0] = p->p_pid;
  866                         if (status)
  867                                 *status = W_STOPCODE(p->p_xstat);
  868 
  869                         PROC_LOCK(q);
  870                         sigqueue_take(p->p_ksi);
  871                         PROC_UNLOCK(q);
  872                         PROC_UNLOCK(p);
  873 
  874                         return (0);
  875                 }
  876                 PROC_SUNLOCK(p);
  877                 if (options & WCONTINUED && (p->p_flag & P_CONTINUED)) {
  878                         sx_xunlock(&proctree_lock);
  879                         td->td_retval[0] = p->p_pid;
  880                         p->p_flag &= ~P_CONTINUED;
  881 
  882                         PROC_LOCK(q);
  883                         sigqueue_take(p->p_ksi);
  884                         PROC_UNLOCK(q);
  885                         PROC_UNLOCK(p);
  886 
  887                         if (status)
  888                                 *status = SIGCONT;
  889                         return (0);
  890                 }
  891                 PROC_UNLOCK(p);
  892         }
  893         if (nfound == 0) {
  894                 sx_xunlock(&proctree_lock);
  895                 return (ECHILD);
  896         }
  897         if (options & WNOHANG) {
  898                 sx_xunlock(&proctree_lock);
  899                 td->td_retval[0] = 0;
  900                 return (0);
  901         }
  902         PROC_LOCK(q);
  903         sx_xunlock(&proctree_lock);
  904         if (q->p_flag & P_STATCHILD) {
  905                 q->p_flag &= ~P_STATCHILD;
  906                 error = 0;
  907         } else
  908                 error = msleep(q, &q->p_mtx, PWAIT | PCATCH, "wait", 0);
  909         PROC_UNLOCK(q);
  910         if (error)
  911                 return (error); 
  912         goto loop;
  913 }
  914 
  915 /*
  916  * Make process 'parent' the new parent of process 'child'.
  917  * Must be called with an exclusive hold of proctree lock.
  918  */
  919 void
  920 proc_reparent(struct proc *child, struct proc *parent)
  921 {
  922 
  923         sx_assert(&proctree_lock, SX_XLOCKED);
  924         PROC_LOCK_ASSERT(child, MA_OWNED);
  925         if (child->p_pptr == parent)
  926                 return;
  927 
  928         PROC_LOCK(child->p_pptr);
  929         sigqueue_take(child->p_ksi);
  930         PROC_UNLOCK(child->p_pptr);
  931         LIST_REMOVE(child, p_sibling);
  932         LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
  933         child->p_pptr = parent;
  934 }

Cache object: 6dffaf60a81c52f3bfe36ff888642712


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