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

     /*
      * Copyright (c) 1982, 1986, 1989, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
      * the permission of UNIX System Laboratories, Inc.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_exit.c 8.7 (Berkeley) 2/12/94
     * $FreeBSD$
     */
    
    #include "opt_compat.h"
    #include "opt_ktrace.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/sysproto.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/proc.h>
    #include <sys/pioctl.h>
    #include <sys/tty.h>
    #include <sys/wait.h>
    #include <sys/vnode.h>
    #include <sys/resourcevar.h>
    #include <sys/signalvar.h>
    #include <sys/ptrace.h>
    #include <sys/acct.h>           /* for acct_process() function prototype */
    #include <sys/filedesc.h>
    #include <sys/shm.h>
    #include <sys/sem.h>
    #include <sys/aio.h>
    
    #ifdef COMPAT_43
    #include <machine/reg.h>
    #include <machine/psl.h>
    #endif
    #include <machine/limits.h>     /* for UCHAR_MAX = typeof(p_priority)_MAX */
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <sys/lock.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <vm/vm_zone.h>
    #include <sys/user.h>
    
    static MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
    
    static int wait1 __P((struct proc *, struct wait_args *, int));
    
    /*
     * callout list for things to do at exit time
     */
    typedef struct exit_list_element {
            struct exit_list_element *next;
            exitlist_fn function;
    } *ele_p;
    
    static ele_p exit_list;
    
    /*
     * exit --
     *      Death of process.
     */
    void
    exit(p, uap)
            struct proc *p;
            struct rexit_args /* {
                   int     rval;
           } */ *uap;
   {
   
           exit1(p, W_EXITCODE(uap->rval, 0));
           /* NOTREACHED */
   }
   
   /*
    * Exit: deallocate address space and other resources, change proc state
    * to zombie, and unlink proc from allproc and parent's lists.  Save exit
    * status and rusage for wait().  Check for child processes and orphan them.
    */
   void
   exit1(p, rv)
           register struct proc *p;
           int rv;
   {
           register struct proc *q, *nq;
           register struct vmspace *vm;
           ele_p ep = exit_list;
   
           if (p->p_pid == 1) {
                   printf("init died (signal %d, exit %d)\n",
                       WTERMSIG(rv), WEXITSTATUS(rv));
                   panic("Going nowhere without my init!");
           }
   
           aio_proc_rundown(p);
   
           /* are we a task leader? */
           if(p == p->p_leader) {
                   struct kill_args killArgs;
                   killArgs.signum = SIGKILL;
                   q = p->p_peers;
                   while(q) {
                           killArgs.pid = q->p_pid;
                           /*
                            * The interface for kill is better
                            * than the internal signal
                            */
                           kill(p, &killArgs);
                           nq = q;
                           q = q->p_peers;
                   }
                   while (p->p_peers) 
                     tsleep((caddr_t)p, PWAIT, "exit1", 0);
           } 
   
   #ifdef PGINPROF
           vmsizmon();
   #endif
           STOPEVENT(p, S_EXIT, rv);
   
           /* 
            * Check if any LKMs need anything done at process exit.
            * e.g. SYSV IPC stuff
            * XXX what if one of these generates an error?
            */
           while (ep) {
                   (*ep->function)(p);
                   ep = ep->next;
           }
   
           if (p->p_flag & P_PROFIL)
                   stopprofclock(p);
           MALLOC(p->p_ru, struct rusage *, sizeof(struct rusage),
                   M_ZOMBIE, M_WAITOK);
           /*
            * If parent is waiting for us to exit or exec,
            * P_PPWAIT is set; we will wakeup the parent below.
            */
           p->p_flag &= ~(P_TRACED | P_PPWAIT);
           p->p_flag |= P_WEXIT;
           p->p_siglist = 0;
           if (timevalisset(&p->p_realtimer.it_value))
                   untimeout(realitexpire, (caddr_t)p, p->p_ithandle);
   
           /*
            * Reset any sigio structures pointing to us as a result of
            * F_SETOWN with our pid.
            */
           funsetownlst(&p->p_sigiolst);
   
           /*
            * Close open files and release open-file table.
            * This may block!
            */
           fdfree(p);
   
           if(p->p_leader->p_peers) {
                   q = p->p_leader;
                   while(q->p_peers != p)
                           q = q->p_peers;
                   q->p_peers = p->p_peers;
                   wakeup((caddr_t)p->p_leader);
           }
   
           /*
            * XXX Shutdown SYSV semaphores
            */
           semexit(p);
   
           /* The next two chunks should probably be moved to vmspace_exit. */
           vm = p->p_vmspace;
           /*
            * Release user portion of address space.
            * This releases references to vnodes,
            * which could cause I/O if the file has been unlinked.
            * Need to do this early enough that we can still sleep.
            * Can't free the entire vmspace as the kernel stack
            * may be mapped within that space also.
            */
           if (vm->vm_refcnt == 1) {
                   if (vm->vm_shm)
                           shmexit(p);
                   pmap_remove_pages(&vm->vm_pmap, VM_MIN_ADDRESS,
                       VM_MAXUSER_ADDRESS);
                   (void) vm_map_remove(&vm->vm_map, VM_MIN_ADDRESS,
                       VM_MAXUSER_ADDRESS);
           }
   
           if (SESS_LEADER(p)) {
                   register struct session *sp = p->p_session;
   
                   if (sp->s_ttyvp) {
                           /*
                            * Controlling process.
                            * Signal foreground pgrp,
                            * drain controlling terminal
                            * and revoke access to controlling terminal.
                            */
                           if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) {
                                   if (sp->s_ttyp->t_pgrp)
                                           pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
                                   (void) ttywait(sp->s_ttyp);
                                   /*
                                    * The tty could have been revoked
                                    * if we blocked.
                                    */
                                   if (sp->s_ttyvp)
                                           VOP_REVOKE(sp->s_ttyvp, REVOKEALL);
                           }
                           if (sp->s_ttyvp)
                                   vrele(sp->s_ttyvp);
                           sp->s_ttyvp = NULL;
                           /*
                            * s_ttyp is not zero'd; we use this to indicate
                            * that the session once had a controlling terminal.
                            * (for logging and informational purposes)
                            */
                   }
                   sp->s_leader = NULL;
           }
           fixjobc(p, p->p_pgrp, 0);
           (void)acct_process(p);
   #ifdef KTRACE
           /*
            * release trace file
            */
           p->p_traceflag = 0;     /* don't trace the vrele() */
           if (p->p_tracep)
                   vrele(p->p_tracep);
   #endif
           /*
            * Remove proc from allproc queue and pidhash chain.
            * Place onto zombproc.  Unlink from parent's child list.
            */
           LIST_REMOVE(p, p_list);
           LIST_INSERT_HEAD(&zombproc, p, p_list);
           p->p_stat = SZOMB;
   
           LIST_REMOVE(p, p_hash);
   
           q = p->p_children.lh_first;
           if (q)          /* only need this if any child is S_ZOMB */
                   wakeup((caddr_t) initproc);
           for (; q != 0; q = nq) {
                   nq = q->p_sibling.le_next;
                   LIST_REMOVE(q, p_sibling);
                   LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling);
                   q->p_pptr = initproc;
                   q->p_sigparent = SIGCHLD;
                   /*
                    * Traced processes are killed
                    * since their existence means someone is screwing up.
                    */
                   if (q->p_flag & P_TRACED) {
                           q->p_flag &= ~P_TRACED;
                           psignal(q, SIGKILL);
                   }
           }
   
           /*
            * Save exit status and final rusage info, adding in child rusage
            * info and self times.
            */
           p->p_xstat = rv;
           *p->p_ru = p->p_stats->p_ru;
           calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL);
           ruadd(p->p_ru, &p->p_stats->p_cru);
   
           /*
            * Notify parent that we're gone.  If parent has the P_NOCLDWAIT
            * flag set, notify process 1 instead (and hope it will handle
            * this situation).
            */
           if (p->p_pptr->p_procsig->ps_flag & P_NOCLDWAIT) {
                   struct proc *pp = p->p_pptr;
                   proc_reparent(p, initproc);
                   /*
                    * If this was the last child of our parent, notify
                    * parent, so in case he was wait(2)ing, he will
                    * continue.
                    */
                   if (LIST_EMPTY(&pp->p_children))
                           wakeup((caddr_t)pp);
           }
   
           if (p->p_sigparent && p->p_pptr != initproc) {
                   psignal(p->p_pptr, p->p_sigparent);
           } else {
                   psignal(p->p_pptr, SIGCHLD);
           }
   
           wakeup((caddr_t)p->p_pptr);
   #if defined(tahoe)
           /* move this to cpu_exit */
           p->p_addr->u_pcb.pcb_savacc.faddr = (float *)NULL;
   #endif
           /*
            * Clear curproc after we've done all operations
            * that could block, and before tearing down the rest
            * of the process state that might be used from clock, etc.
            * Also, can't clear curproc while we're still runnable,
            * as we're not on a run queue (we are current, just not
            * a proper proc any longer!).
            *
            * Other substructures are freed from wait().
            */
           curproc = NULL;
           if (--p->p_limit->p_refcnt == 0) {
                   FREE(p->p_limit, M_SUBPROC);
                   p->p_limit = NULL;
           }
   
           /*
            * Finally, call machine-dependent code to release the remaining
            * resources including address space, the kernel stack and pcb.
            * The address space is released by "vmspace_free(p->p_vmspace)";
            * This is machine-dependent, as we may have to change stacks
            * or ensure that the current one isn't reallocated before we
            * finish.  cpu_exit will end with a call to cpu_switch(), finishing
            * our execution (pun intended).
            */
           cpu_exit(p);
   }
   
   #ifdef COMPAT_43
   #if defined(hp300) || defined(luna68k)
   #include <machine/frame.h>
   #define GETPS(rp)       ((struct frame *)(rp))->f_sr
   #else
   #define GETPS(rp)       (rp)[PS]
   #endif
   
   int
   owait(p, uap)
           struct proc *p;
           register struct owait_args /* {
                   int     dummy;
           } */ *uap;
   {
           struct wait_args w;
   
   #ifdef PSL_ALLCC
           if ((GETPS(p->p_md.md_regs) & PSL_ALLCC) != PSL_ALLCC) {
                   w.options = 0;
                   w.rusage = NULL;
           } else {
                   w.options = p->p_md.md_regs[R0];
                   w.rusage = (struct rusage *)p->p_md.md_regs[R1];
           }
   #else
           w.options = 0;
           w.rusage = NULL;
   #endif
           w.pid = WAIT_ANY;
           w.status = NULL;
           return (wait1(p, &w, 1));
   }
   #endif /* COMPAT_43 */
   
   int
   wait4(p, uap)
           struct proc *p;
           struct wait_args *uap;
   {
   
           return (wait1(p, uap, 0));
   }
   
   static int
   wait1(q, uap, compat)
           register struct proc *q;
           register struct wait_args /* {
                   int pid;
                   int *status;
                   int options;
                   struct rusage *rusage;
           } */ *uap;
           int compat;
   {
           register int nfound;
           register struct proc *p, *t;
           int status, error;
   
           if (uap->pid == 0)
                   uap->pid = -q->p_pgid;
           if (uap->options &~ (WUNTRACED|WNOHANG|WLINUXCLONE))
                   return (EINVAL);
   loop:
           nfound = 0;
           for (p = q->p_children.lh_first; p != 0; p = p->p_sibling.le_next) {
                   if (uap->pid != WAIT_ANY &&
                       p->p_pid != uap->pid && p->p_pgid != -uap->pid)
                           continue;
   
                   /* This special case handles a kthread spawned by linux_clone 
                    * (see linux_misc.c).  The linux_wait4 and linux_waitpid functions
                    * need to be able to distinguish between waiting on a process and
                    * waiting on a thread.  It is a thread if p_sigparent is not SIGCHLD,
                    * and the WLINUXCLONE option signifies we want to wait for threads
                    * and not processes.
                    */
                   if ((p->p_sigparent != SIGCHLD) ^ ((uap->options & WLINUXCLONE) != 0))
                           continue;
   
                   nfound++;
                   if (p->p_stat == SZOMB) {
                           /* charge childs scheduling cpu usage to parent */
                           if (curproc->p_pid != 1) {
                                   curproc->p_estcpu = min(curproc->p_estcpu +
                                       p->p_estcpu, UCHAR_MAX);
                           }
   
                           q->p_retval[0] = p->p_pid;
   #ifdef COMPAT_43
                           if (compat)
                                   q->p_retval[1] = p->p_xstat;
                           else
   #endif
                           if (uap->status) {
                                   status = p->p_xstat;    /* convert to int */
                                   if ((error = copyout((caddr_t)&status,
                                       (caddr_t)uap->status, sizeof(status))))
                                           return (error);
                           }
                           if (uap->rusage && (error = copyout((caddr_t)p->p_ru,
                               (caddr_t)uap->rusage, sizeof (struct rusage))))
                                   return (error);
                           /*
                            * If we got the child via a ptrace 'attach',
                            * we need to give it back to the old parent.
                            */
                           if (p->p_oppid && (t = pfind(p->p_oppid))) {
                                   p->p_oppid = 0;
                                   proc_reparent(p, t);
                                   psignal(t, SIGCHLD);
                                   wakeup((caddr_t)t);
                                   return (0);
                           }
                           p->p_xstat = 0;
                           ruadd(&q->p_stats->p_cru, p->p_ru);
                           FREE(p->p_ru, M_ZOMBIE);
                           p->p_ru = NULL;
   
                           /*
                            * Decrement the count of procs running with this uid.
                            */
                           (void)chgproccnt(p->p_cred->p_ruid, -1);
   
                           /*
                            * Release reference to text vnode
                            */
                           if (p->p_textvp)
                                   vrele(p->p_textvp);
   
                           /*
                            * Free up credentials.
                            */
                           if (--p->p_cred->p_refcnt == 0) {
                                   crfree(p->p_cred->pc_ucred);
                                   FREE(p->p_cred, M_SUBPROC);
                                   p->p_cred = NULL;
                           }
   
                           /*
                            * Finally finished with old proc entry.
                            * Unlink it from its process group and free it.
                            */
                           leavepgrp(p);
                           LIST_REMOVE(p, p_list); /* off zombproc */
                           LIST_REMOVE(p, p_sibling);
   
                           if (--p->p_procsig->ps_refcnt == 0) {
                                   if (p->p_sigacts != &p->p_addr->u_sigacts)
                                           FREE(p->p_sigacts, M_SUBPROC);
                                   FREE(p->p_procsig, M_SUBPROC);
                                   p->p_procsig = NULL;
                           }
   
                           /*
                            * Give machine-dependent layer a chance
                            * to free anything that cpu_exit couldn't
                            * release while still running in process context.
                            */
                           cpu_wait(p);
                           zfree(proc_zone, p);
                           nprocs--;
                           return (0);
                   }
                   if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 &&
                       (p->p_flag & P_TRACED || uap->options & WUNTRACED)) {
                           p->p_flag |= P_WAITED;
                           q->p_retval[0] = p->p_pid;
   #ifdef COMPAT_43
                           if (compat) {
                                   q->p_retval[1] = W_STOPCODE(p->p_xstat);
                                   error = 0;
                           } else
   #endif
                           if (uap->status) {
                                   status = W_STOPCODE(p->p_xstat);
                                   error = copyout((caddr_t)&status,
                                           (caddr_t)uap->status, sizeof(status));
                           } else
                                   error = 0;
                           return (error);
                   }
           }
           if (nfound == 0)
                   return (ECHILD);
           if (uap->options & WNOHANG) {
                   q->p_retval[0] = 0;
                   return (0);
           }
           if ((error = tsleep((caddr_t)q, PWAIT | PCATCH, "wait", 0)))
                   return (error);
           goto loop;
   }
   
   /*
    * make process 'parent' the new parent of process 'child'.
    */
   void
   proc_reparent(child, parent)
           register struct proc *child;
           register struct proc *parent;
   {
   
           if (child->p_pptr == parent)
                   return;
   
           LIST_REMOVE(child, p_sibling);
           LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
           child->p_pptr = parent;
   }
   
   /*
    * The next two functions are to handle adding/deleting items on the
    * exit callout list
    * 
    * at_exit():
    * Take the arguments given and put them onto the exit callout list,
    * However first make sure that it's not already there.
    * returns 0 on success.
    */
   int
   at_exit(function)
           exitlist_fn function;
   {
           ele_p ep;
   
           /* Be noisy if the programmer has lost track of things */
           if (rm_at_exit(function)) 
                   printf("exit callout entry already present\n");
           ep = malloc(sizeof(*ep), M_TEMP, M_NOWAIT);
           if (ep == NULL)
                   return (ENOMEM);
           ep->next = exit_list;
           ep->function = function;
           exit_list = ep;
           return (0);
   }
   /*
    * Scan the exit callout list for the given items and remove them.
    * Returns the number of items removed.
    * Logically this can only be 0 or 1.
    */
   int
   rm_at_exit(function)
           exitlist_fn function;
   {
           ele_p *epp, ep;
           int count;
   
           count = 0;
           epp = &exit_list;
           ep = *epp;
           while (ep) {
                   if (ep->function == function) {
                           *epp = ep->next;
                           free(ep, M_TEMP);
                           count++;
                   } else {
                           epp = &ep->next;
                   }
                   ep = *epp;
           }
           return (count);
   }
   
   void check_sigacts (void)
   {
           struct proc *p = curproc;
           struct sigacts *pss;
           int s;
   
           if (p->p_procsig->ps_refcnt == 1 &&
               p->p_sigacts != &p->p_addr->u_sigacts) {
                   pss = p->p_sigacts;
                   s = splhigh();
                   p->p_addr->u_sigacts = *pss;
                   p->p_sigacts = &p->p_addr->u_sigacts;
                   splx(s);
                   FREE(pss, M_SUBPROC);
           }
   }
   

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