common/os/exit.c

	exit.c revision 8fd04b8338ed5093ec2d1e668fa620b7de44c177
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>
#include <sys/cred.h>
#include <sys/user.h>
#include <sys/errno.h>
#include <sys/proc.h>
#include <sys/ucontext.h>
#include <sys/procfs.h>
#include <sys/vnode.h>
#include <sys/acct.h>
#include <sys/var.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/wait.h>
#include <sys/siginfo.h>
#include <sys/procset.h>
#include <sys/class.h>
#include <sys/file.h>
#include <sys/session.h>
#include <sys/kmem.h>
#include <sys/vtrace.h>
#include <sys/prsystm.h>
#include <sys/ipc.h>
#include <sys/sem_impl.h>
#include <c2/audit.h>
#include <sys/aio_impl.h>
#include <vm/as.h>
#include <sys/poll.h>
#include <sys/door.h>
#include <sys/lwpchan_impl.h>
#include <sys/utrap.h>
#include <sys/task.h>
#include <sys/exacct.h>
#include <sys/cyclic.h>
#include <sys/schedctl.h>
#include <sys/rctl.h>
#include <sys/contract_impl.h>
#include <sys/contract/process_impl.h>
#include <sys/list.h>
#include <sys/dtrace.h>
#include <sys/pool.h>
#include <sys/sdt.h>
#include <sys/corectl.h>
#include <sys/brand.h>
#include <sys/libc_kernel.h>

/*
 * convert code/data pair into old style wait status
 */
int
wstat(int code, int data)
{
    int stat = (data & 0377);

    switch (code) {
    case CLD_EXITED:
        stat <<= 8;
        break;
    case CLD_DUMPED:
        stat |= WCOREFLG;
        break;
    case CLD_KILLED:
        break;
    case CLD_TRAPPED:
    case CLD_STOPPED:
        stat <<= 8;
        stat |= WSTOPFLG;
        break;
    case CLD_CONTINUED:
        stat = WCONTFLG;
        break;
    default:
        cmn_err(CE_PANIC, "wstat: bad code");
        /* NOTREACHED */
    }
    return (stat);
}

static char *
exit_reason(char *buf, size_t bufsz, int what, int why)
{
    switch (why) {
    case CLD_EXITED:
        (void) snprintf(buf, bufsz, "exited with status %d", what);
        break;
    case CLD_KILLED:
        (void) snprintf(buf, bufsz, "exited on fatal signal %d", what);
        break;
    case CLD_DUMPED:
        (void) snprintf(buf, bufsz, "core dumped on signal %d", what);
        break;
    default:
        (void) snprintf(buf, bufsz, "encountered unknown error "
            "(%d, %d)", why, what);
        break;
    }

    return (buf);
}

/*
 * exit system call: pass back caller's arg.
 */
void
rexit(int rval)
{
    exit(CLD_EXITED, rval);
}

/*
 * Called by proc_exit() when a zone's init exits, presumably because
 * it failed.  As long as the given zone is still in the "running"
 * state, we will re-exec() init, but first we need to reset things
 * which are usually inherited across exec() but will break init's
 * assumption that it is being exec()'d from a virgin process.  Most
 * importantly this includes closing all file descriptors (exec only
 * closes those marked close-on-exec) and resetting signals (exec only
 * resets handled signals, and we need to clear any signals which
 * killed init).  Anything else that exec(2) says would be inherited,
 * but would affect the execution of init, needs to be reset.
 */
static int
restart_init(int what, int why)
{
    kthread_t *t = curthread;
    klwp_t *lwp = ttolwp(t);
    proc_t *p = ttoproc(t);
    user_t *up = PTOU(p);

    vnode_t *oldcd, *oldrd;
    int i, err;
    char reason_buf[64];

    /*
     * Let zone admin (and global zone admin if this is for a non-global
     * zone) know that init has failed and will be restarted.
     */
    zcmn_err(p->p_zone->zone_id, CE_WARN,
        "init(1M) %s: restarting automatically",
        exit_reason(reason_buf, sizeof (reason_buf), what, why));

    if (!INGLOBALZONE(p)) {
        cmn_err(CE_WARN, "init(1M) for zone %s (pid %d) %s: "
            "restarting automatically",
            p->p_zone->zone_name, p->p_pid, reason_buf);
    }

    /*
     * Remove any fpollinfo_t's for this (last) thread from our file
     * descriptors so closeall() can ASSERT() that they're all gone.
     * Then close all open file descriptors in the process.
     */
    pollcleanup();
    closeall(P_FINFO(p));

    /*
     * Grab p_lock and begin clearing miscellaneous global process
     * state that needs to be reset before we exec the new init(1M).
     */

    mutex_enter(&p->p_lock);
    prbarrier(p);

    p->p_flag &= ~(SKILLED | SEXTKILLED | SEXITING | SDOCORE);
    up->u_cmask = CMASK;

    sigemptyset(&t->t_hold);
    sigemptyset(&t->t_sig);
    sigemptyset(&t->t_extsig);

    sigemptyset(&p->p_sig);
    sigemptyset(&p->p_extsig);

    sigdelq(p, t, 0);
    sigdelq(p, NULL, 0);

    if (p->p_killsqp) {
        siginfofree(p->p_killsqp);
        p->p_killsqp = NULL;
    }

    /*
     * Reset any signals that are ignored back to the default disposition.
     * Other u_signal members will be cleared when exec calls sigdefault().
     */
    for (i = 1; i < NSIG; i++) {
        if (up->u_signal[i - 1] == SIG_IGN) {
            up->u_signal[i - 1] = SIG_DFL;
            sigemptyset(&up->u_sigmask[i - 1]);
        }
    }

    /*
     * Clear the current signal, any signal info associated with it, and
     * any signal information from contracts and/or contract templates.
     */
    lwp->lwp_cursig = 0;
    lwp->lwp_extsig = 0;
    if (lwp->lwp_curinfo != NULL) {
        siginfofree(lwp->lwp_curinfo);
        lwp->lwp_curinfo = NULL;
    }
    lwp_ctmpl_clear(lwp);

    /*
     * Reset both the process root directory and the current working
     * directory to the root of the zone just as we do during boot.
     */
    VN_HOLD(p->p_zone->zone_rootvp);
    oldrd = up->u_rdir;
    up->u_rdir = p->p_zone->zone_rootvp;

    VN_HOLD(p->p_zone->zone_rootvp);
    oldcd = up->u_cdir;
    up->u_cdir = p->p_zone->zone_rootvp;

    if (up->u_cwd != NULL) {
        refstr_rele(up->u_cwd);
        up->u_cwd = NULL;
    }

    mutex_exit(&p->p_lock);

    if (oldrd != NULL)
        VN_RELE(oldrd);
    if (oldcd != NULL)
        VN_RELE(oldcd);

    /* Free the controlling tty.  (freectty() always assumes curproc.) */
    ASSERT(p == curproc);
    (void) freectty(B_TRUE);

    /*
     * Now exec() the new init(1M) on top of the current process.  If we
     * succeed, the caller will treat this like a successful system call.
     * If we fail, we issue messages and the caller will proceed with exit.
     */
    err = exec_init(p->p_zone->zone_initname, NULL);

    if (err == 0)
        return (0);

    zcmn_err(p->p_zone->zone_id, CE_WARN,
        "failed to restart init(1M) (err=%d): system reboot required", err);

    if (!INGLOBALZONE(p)) {
        cmn_err(CE_WARN, "failed to restart init(1M) for zone %s "
            "(pid %d, err=%d): zoneadm(1M) boot required",
            p->p_zone->zone_name, p->p_pid, err);
    }

    return (-1);
}

/*
 * Release resources.
 * Enter zombie state.
 * Wake up parent and init processes,
 * and dispose of children.
 */
void
exit(int why, int what)
{
    /*
     * If proc_exit() fails, then some other lwp in the process
     * got there first.  We just have to call lwp_exit() to allow
     * the other lwp to finish exiting the process.  Otherwise we're
     * restarting init, and should return.
     */
    if (proc_exit(why, what) != 0) {
        mutex_enter(&curproc->p_lock);
        ASSERT(curproc->p_flag & SEXITLWPS);
        lwp_exit();
        /* NOTREACHED */
    }
}

/*
 * Set the SEXITING flag on the process, after making sure /proc does
 * not have it locked.  This is done in more places than proc_exit(),
 * so it is a separate function.
 */
void
proc_is_exiting(proc_t *p)
{
    mutex_enter(&p->p_lock);
    prbarrier(p);
    p->p_flag |= SEXITING;
    mutex_exit(&p->p_lock);
}

/*
 * Return value:
 *   1 - exitlwps() failed, call (or continue) lwp_exit()
 *   0 - restarting init.  Return through system call path
 */
int
proc_exit(int why, int what)
{
    kthread_t *t = curthread;
    klwp_t *lwp = ttolwp(t);
    proc_t *p = ttoproc(t);
    zone_t *z = p->p_zone;
    timeout_id_t tmp_id;
    int rv;
    proc_t *q;
    task_t *tk;
    vnode_t *exec_vp, *execdir_vp, *cdir, *rdir;
    sigqueue_t *sqp;
    lwpdir_t *lwpdir;
    uint_t lwpdir_sz;
    tidhash_t *tidhash;
    uint_t tidhash_sz;
    ret_tidhash_t *ret_tidhash;
    refstr_t *cwd;
    hrtime_t hrutime, hrstime;
    int evaporate;

    /*
     * Stop and discard the process's lwps except for the current one,
     * unless some other lwp beat us to it.  If exitlwps() fails then
     * return and the calling lwp will call (or continue in) lwp_exit().
     */
    proc_is_exiting(p);
    if (exitlwps(0) != 0)
        return (1);

    mutex_enter(&p->p_lock);
    if (p->p_ttime > 0) {
        /*
         * Account any remaining ticks charged to this process
         * on its way out.
         */
        (void) task_cpu_time_incr(p->p_task, p->p_ttime);
        p->p_ttime = 0;
    }
    mutex_exit(&p->p_lock);

    DTRACE_PROC(lwp__exit);
    DTRACE_PROC1(exit, int, why);

    /*
     * Will perform any brand specific proc exit processing, since this
     * is always the last lwp, will also perform lwp_exit and free brand
     * data
     */
    if (PROC_IS_BRANDED(p)) {
        lwp_detach_brand_hdlrs(lwp);
        brand_clearbrand(p);
    }

    /*
     * Don't let init exit unless zone_start_init() failed its exec, or
     * we are shutting down the zone or the machine.
     *
     * Since we are single threaded, we don't need to lock the
     * following accesses to zone_proc_initpid.
     */
    if (p->p_pid == z->zone_proc_initpid) {
        if (z->zone_boot_err == 0 &&
            zone_status_get(z) < ZONE_IS_SHUTTING_DOWN &&
            zone_status_get(global_zone) < ZONE_IS_SHUTTING_DOWN &&
            z->zone_restart_init == B_TRUE &&
            restart_init(what, why) == 0)
            return (0);
        /*
         * Since we didn't or couldn't restart init, we clear
         * the zone's init state and proceed with exit
         * processing.
         */
        z->zone_proc_initpid = -1;
    }

    lwp_pcb_exit();

    /*
     * Allocate a sigqueue now, before we grab locks.
     * It will be given to sigcld(), below.
     * Special case:  If we will be making the process disappear
     * without a trace because it is either:
     *  * an exiting SSYS process, or
     *  * a posix_spawn() vfork child who requests it,
     * we don't bother to allocate a useless sigqueue.
     */
    evaporate = (p->p_flag & SSYS) || ((p->p_flag & SVFORK) &&
        why == CLD_EXITED && what == _EVAPORATE);
    if (!evaporate)
        sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);

    /*
     * revoke any doors created by the process.
     */
    if (p->p_door_list)
        door_exit();

    /*
     * Release schedctl data structures.
     */
    if (p->p_pagep)
        schedctl_proc_cleanup();

    /*
     * make sure all pending kaio has completed.
     */
    if (p->p_aio)
        aio_cleanup_exit();

    /*
     * discard the lwpchan cache.
     */
    if (p->p_lcp != NULL)
        lwpchan_destroy_cache(0);

    /*
     * Clean up any DTrace helper actions or probes for the process.
     */
    if (p->p_dtrace_helpers != NULL) {
        ASSERT(dtrace_helpers_cleanup != NULL);
        (*dtrace_helpers_cleanup)();
    }

    /* untimeout the realtime timers */
    if (p->p_itimer != NULL)
        timer_exit();

    if ((tmp_id = p->p_alarmid) != 0) {
        p->p_alarmid = 0;
        (void) untimeout(tmp_id);
    }

    /*
     * Remove any fpollinfo_t's for this (last) thread from our file
     * descriptors so closeall() can ASSERT() that they're all gone.
     */
    pollcleanup();

    if (p->p_rprof_cyclic != CYCLIC_NONE) {
        mutex_enter(&cpu_lock);
        cyclic_remove(p->p_rprof_cyclic);
        mutex_exit(&cpu_lock);
    }

    mutex_enter(&p->p_lock);

    /*
     * Clean up any DTrace probes associated with this process.
     */
    if (p->p_dtrace_probes) {
        ASSERT(dtrace_fasttrap_exit_ptr != NULL);
        dtrace_fasttrap_exit_ptr(p);
    }

    while ((tmp_id = p->p_itimerid) != 0) {
        p->p_itimerid = 0;
        mutex_exit(&p->p_lock);
        (void) untimeout(tmp_id);
        mutex_enter(&p->p_lock);
    }

    lwp_cleanup();

    /*
     * We are about to exit; prevent our resource associations from
     * being changed.
     */
    pool_barrier_enter();

    /*
     * Block the process against /proc now that we have really
     * acquired p->p_lock (to manipulate p_tlist at least).
     */
    prbarrier(p);

#ifdef  SUN_SRC_COMPAT
    if (code == CLD_KILLED)
        u.u_acflag |= AXSIG;
#endif
    sigfillset(&p->p_ignore);
    sigemptyset(&p->p_siginfo);
    sigemptyset(&p->p_sig);
    sigemptyset(&p->p_extsig);
    sigemptyset(&t->t_sig);
    sigemptyset(&t->t_extsig);
    sigemptyset(&p->p_sigmask);
    sigdelq(p, t, 0);
    lwp->lwp_cursig = 0;
    lwp->lwp_extsig = 0;
    p->p_flag &= ~(SKILLED | SEXTKILLED);
    if (lwp->lwp_curinfo) {
        siginfofree(lwp->lwp_curinfo);
        lwp->lwp_curinfo = NULL;
    }

    t->t_proc_flag |= TP_LWPEXIT;
    ASSERT(p->p_lwpcnt == 1 && p->p_zombcnt == 0);
    prlwpexit(t);       /* notify /proc */
    lwp_hash_out(p, t->t_tid);
    prexit(p);

    p->p_lwpcnt = 0;
    p->p_tlist = NULL;
    sigqfree(p);
    term_mstate(t);
    p->p_mterm = gethrtime();

    exec_vp = p->p_exec;
    execdir_vp = p->p_execdir;
    p->p_exec = NULLVP;
    p->p_execdir = NULLVP;
    mutex_exit(&p->p_lock);

    pr_free_watched_pages(p);

    closeall(P_FINFO(p));

    /* Free the controlling tty.  (freectty() always assumes curproc.) */
    ASSERT(p == curproc);
    (void) freectty(B_TRUE);

#if defined(__sparc)
    if (p->p_utraps != NULL)
        utrap_free(p);
#endif
    if (p->p_semacct)           /* IPC semaphore exit */
        semexit(p);
    rv = wstat(why, what);

    acct(rv & 0xff);
    exacct_commit_proc(p, rv);

    /*
     * Release any resources associated with C2 auditing
     */
    if (audit_active) {
        /*
         * audit exit system call
         */
        audit_exit(why, what);
    }

    /*
     * Free address space.
     */
    relvm();

    if (exec_vp) {
        /*
         * Close this executable which has been opened when the process
         * was created by getproc().
         */
        (void) VOP_CLOSE(exec_vp, FREAD, 1, (offset_t)0, CRED(), NULL);
        VN_RELE(exec_vp);
    }
    if (execdir_vp)
        VN_RELE(execdir_vp);

    /*
     * Release held contracts.
     */
    contract_exit(p);

    /*
     * Depart our encapsulating process contract.
     */
    if ((p->p_flag & SSYS) == 0) {
        ASSERT(p->p_ct_process);
        contract_process_exit(p->p_ct_process, p, rv);
    }

    /*
     * Remove pool association, and block if requested by pool_do_bind.
     */
    mutex_enter(&p->p_lock);
    ASSERT(p->p_pool->pool_ref > 0);
    atomic_add_32(&p->p_pool->pool_ref, -1);
    p->p_pool = pool_default;
    /*
     * Now that our address space has been freed and all other threads
     * in this process have exited, set the PEXITED pool flag.  This
     * tells the pools subsystems to ignore this process if it was
     * requested to rebind this process to a new pool.
     */
    p->p_poolflag |= PEXITED;
    pool_barrier_exit();
    mutex_exit(&p->p_lock);

    mutex_enter(&pidlock);

    /*
     * Delete this process from the newstate list of its parent. We
     * will put it in the right place in the sigcld in the end.
     */
    delete_ns(p->p_parent, p);

    /*
     * Reassign the orphans to the next of kin.
     * Don't rearrange init's orphanage.
     */
    if ((q = p->p_orphan) != NULL && p != proc_init) {

        proc_t *nokp = p->p_nextofkin;

        for (;;) {
            q->p_nextofkin = nokp;
            if (q->p_nextorph == NULL)
                break;
            q = q->p_nextorph;
        }
        q->p_nextorph = nokp->p_orphan;
        nokp->p_orphan = p->p_orphan;
        p->p_orphan = NULL;
    }

    /*
     * Reassign the children to init.
     * Don't try to assign init's children to init.
     */
    if ((q = p->p_child) != NULL && p != proc_init) {
        struct proc *np;
        struct proc *initp = proc_init;
        boolean_t   setzonetop = B_FALSE;

        if (!INGLOBALZONE(curproc))
            setzonetop = B_TRUE;

        pgdetach(p);

        do {
            np = q->p_sibling;
            /*
             * Delete it from its current parent new state
             * list and add it to init new state list
             */
            delete_ns(q->p_parent, q);

            q->p_ppid = 1;
            q->p_pidflag &= ~(CLDNOSIGCHLD | CLDWAITPID);
            if (setzonetop) {
                mutex_enter(&q->p_lock);
                q->p_flag |= SZONETOP;
                mutex_exit(&q->p_lock);
            }
            q->p_parent = initp;

            /*
             * Since q will be the first child,
             * it will not have a previous sibling.
             */
            q->p_psibling = NULL;
            if (initp->p_child) {
                initp->p_child->p_psibling = q;
            }
            q->p_sibling = initp->p_child;
            initp->p_child = q;
            if (q->p_proc_flag & P_PR_PTRACE) {
                mutex_enter(&q->p_lock);
                sigtoproc(q, NULL, SIGKILL);
                mutex_exit(&q->p_lock);
            }
            /*
             * sigcld() will add the child to parents
             * newstate list.
             */
            if (q->p_stat == SZOMB)
                sigcld(q, NULL);
        } while ((q = np) != NULL);

        p->p_child = NULL;
        ASSERT(p->p_child_ns == NULL);
    }

    TRACE_1(TR_FAC_PROC, TR_PROC_EXIT, "proc_exit: %p", p);

    mutex_enter(&p->p_lock);
    CL_EXIT(curthread); /* tell the scheduler that curthread is exiting */

    /*
     * Have our task accummulate our resource usage data before they
     * become contaminated by p_cacct etc., and before we renounce
     * membership of the task.
     *
     * We do this regardless of whether or not task accounting is active.
     * This is to avoid having nonsense data reported for this task if
     * task accounting is subsequently enabled. The overhead is minimal;
     * by this point, this process has accounted for the usage of all its
     * LWPs. We nonetheless do the work here, and under the protection of
     * pidlock, so that the movement of the process's usage to the task
     * happens at the same time as the removal of the process from the
     * task, from the point of view of exacct_snapshot_task_usage().
     */
    exacct_update_task_mstate(p);

    hrutime = mstate_aggr_state(p, LMS_USER);
    hrstime = mstate_aggr_state(p, LMS_SYSTEM);
    p->p_utime = (clock_t)NSEC_TO_TICK(hrutime) + p->p_cutime;
    p->p_stime = (clock_t)NSEC_TO_TICK(hrstime) + p->p_cstime;

    p->p_acct[LMS_USER] += p->p_cacct[LMS_USER];
    p->p_acct[LMS_SYSTEM]   += p->p_cacct[LMS_SYSTEM];
    p->p_acct[LMS_TRAP] += p->p_cacct[LMS_TRAP];
    p->p_acct[LMS_TFAULT]   += p->p_cacct[LMS_TFAULT];
    p->p_acct[LMS_DFAULT]   += p->p_cacct[LMS_DFAULT];
    p->p_acct[LMS_KFAULT]   += p->p_cacct[LMS_KFAULT];
    p->p_acct[LMS_USER_LOCK] += p->p_cacct[LMS_USER_LOCK];
    p->p_acct[LMS_SLEEP]    += p->p_cacct[LMS_SLEEP];
    p->p_acct[LMS_WAIT_CPU] += p->p_cacct[LMS_WAIT_CPU];
    p->p_acct[LMS_STOPPED]  += p->p_cacct[LMS_STOPPED];

    p->p_ru.minflt  += p->p_cru.minflt;
    p->p_ru.majflt  += p->p_cru.majflt;
    p->p_ru.nswap   += p->p_cru.nswap;
    p->p_ru.inblock += p->p_cru.inblock;
    p->p_ru.oublock += p->p_cru.oublock;
    p->p_ru.msgsnd  += p->p_cru.msgsnd;
    p->p_ru.msgrcv  += p->p_cru.msgrcv;
    p->p_ru.nsignals += p->p_cru.nsignals;
    p->p_ru.nvcsw   += p->p_cru.nvcsw;
    p->p_ru.nivcsw  += p->p_cru.nivcsw;
    p->p_ru.sysc    += p->p_cru.sysc;
    p->p_ru.ioch    += p->p_cru.ioch;

    p->p_stat = SZOMB;
    p->p_proc_flag &= ~P_PR_PTRACE;
    p->p_wdata = what;
    p->p_wcode = (char)why;

    cdir = PTOU(p)->u_cdir;
    rdir = PTOU(p)->u_rdir;
    cwd = PTOU(p)->u_cwd;

    ASSERT(cdir != NULL || p->p_parent == &p0);

    /*
     * Release resource controls, as they are no longer enforceable.
     */
    rctl_set_free(p->p_rctls);

    /*
     * Give up task and project memberships.  Decrement tk_nlwps counter
     * for our task.max-lwps resource control.  An extended accounting
     * record, if that facility is active, is scheduled to be written.
     * Zombie processes are false members of task0 for the remainder of
     * their lifetime; no accounting information is recorded for them.
     */
    tk = p->p_task;

    mutex_enter(&p->p_zone->zone_nlwps_lock);
    tk->tk_nlwps--;
    tk->tk_proj->kpj_nlwps--;
    p->p_zone->zone_nlwps--;
    mutex_exit(&p->p_zone->zone_nlwps_lock);
    task_detach(p);
    p->p_task = task0p;

    /*
     * Clear the lwp directory and the lwpid hash table
     * now that /proc can't bother us any more.
     * We free the memory below, after dropping p->p_lock.
     */
    lwpdir = p->p_lwpdir;
    lwpdir_sz = p->p_lwpdir_sz;
    tidhash = p->p_tidhash;
    tidhash_sz = p->p_tidhash_sz;
    ret_tidhash = p->p_ret_tidhash;
    p->p_lwpdir = NULL;
    p->p_lwpfree = NULL;
    p->p_lwpdir_sz = 0;
    p->p_tidhash = NULL;
    p->p_tidhash_sz = 0;
    p->p_ret_tidhash = NULL;

    /*
     * If the process has context ops installed, call the exit routine
     * on behalf of this last remaining thread. Normally exitpctx() is
     * called during thread_exit() or lwp_exit(), but because this is the
     * last thread in the process, we must call it here. By the time
     * thread_exit() is called (below), the association with the relevant
     * process has been lost.
     *
     * We also free the context here.
     */
    if (p->p_pctx) {
        kpreempt_disable();
        exitpctx(p);
        kpreempt_enable();

        freepctx(p, 0);
    }

    /*
     * curthread's proc pointer is changed to point to the 'sched'
     * process for the corresponding zone, except in the case when
     * the exiting process is in fact a zsched instance, in which
     * case the proc pointer is set to p0.  We do so, so that the
     * process still points at the right zone when we call the VN_RELE()
     * below.
     *
     * This is because curthread's original proc pointer can be freed as
     * soon as the child sends a SIGCLD to its parent.  We use zsched so
     * that for user processes, even in the final moments of death, the
     * process is still associated with its zone.
     */
    if (p != t->t_procp->p_zone->zone_zsched)
        t->t_procp = t->t_procp->p_zone->zone_zsched;
    else
        t->t_procp = &p0;

    mutex_exit(&p->p_lock);
    if (!evaporate) {
        p->p_pidflag &= ~CLDPEND;
        sigcld(p, sqp);
    } else {
        /*
         * Do what sigcld() would do if the disposition
         * of the SIGCHLD signal were set to be ignored.
         */
        cv_broadcast(&p->p_srwchan_cv);
        freeproc(p);
    }
    mutex_exit(&pidlock);

    /*
     * We don't release u_cdir and u_rdir until SZOMB is set.
     * This protects us against dofusers().
     */
    if (cdir)
        VN_RELE(cdir);
    if (rdir)
        VN_RELE(rdir);
    if (cwd)
        refstr_rele(cwd);

    /*
     * task_rele() may ultimately cause the zone to go away (or
     * may cause the last user process in a zone to go away, which
     * signals zsched to go away).  So prior to this call, we must
     * no longer point at zsched.
     */
    t->t_procp = &p0;
    task_rele(tk);

    kmem_free(lwpdir, lwpdir_sz * sizeof (lwpdir_t));
    kmem_free(tidhash, tidhash_sz * sizeof (tidhash_t));
    while (ret_tidhash != NULL) {
        ret_tidhash_t *next = ret_tidhash->rth_next;
        kmem_free(ret_tidhash->rth_tidhash,
            ret_tidhash->rth_tidhash_sz * sizeof (tidhash_t));
        kmem_free(ret_tidhash, sizeof (*ret_tidhash));
        ret_tidhash = next;
    }

    thread_exit();
    /* NOTREACHED */
}

/*
 * Format siginfo structure for wait system calls.
 */
void
winfo(proc_t *pp, k_siginfo_t *ip, int waitflag)
{
    ASSERT(MUTEX_HELD(&pidlock));

    bzero(ip, sizeof (k_siginfo_t));
    ip->si_signo = SIGCLD;
    ip->si_code = pp->p_wcode;
    ip->si_pid = pp->p_pid;
    ip->si_ctid = PRCTID(pp);
    ip->si_zoneid = pp->p_zone->zone_id;
    ip->si_status = pp->p_wdata;
    ip->si_stime = pp->p_stime;
    ip->si_utime = pp->p_utime;

    if (waitflag) {
        pp->p_wcode = 0;
        pp->p_wdata = 0;
        pp->p_pidflag &= ~CLDPEND;
    }
}

/*
 * Wait system call.
 * Search for a terminated (zombie) child,
 * finally lay it to rest, and collect its status.
 * Look also for stopped children,
 * and pass back status from them.
 */
int
waitid(idtype_t idtype, id_t id, k_siginfo_t *ip, int options)
{
    int found;
    proc_t *cp, *pp;
    int proc_gone;
    int waitflag = !(options & WNOWAIT);

    /*
     * Obsolete flag, defined here only for binary compatibility
     * with old statically linked executables.  Delete this when
     * we no longer care about these old and broken applications.
     */
#define _WNOCHLD    0400
    options &= ~_WNOCHLD;

    if (options == 0 || (options & ~WOPTMASK))
        return (EINVAL);

    switch (idtype) {
    case P_PID:
    case P_PGID:
        if (id < 0 || id >= maxpid)
            return (EINVAL);
        /* FALLTHROUGH */
    case P_ALL:
        break;
    default:
        return (EINVAL);
    }

    pp = ttoproc(curthread);

    /*
     * lock parent mutex so that sibling chain can be searched.
     */
    mutex_enter(&pidlock);

    /*
     * if we are only looking for exited processes and child_ns list
     * is empty no reason to look at all children.
     */
    if (idtype == P_ALL &&
        (options & ~WNOWAIT) == (WNOHANG | WEXITED) &&
        pp->p_child_ns == NULL) {
        if (pp->p_child) {
            mutex_exit(&pidlock);
            bzero(ip, sizeof (k_siginfo_t));
            return (0);
        }
        mutex_exit(&pidlock);
        return (ECHILD);
    }

    while (pp->p_child != NULL) {

        proc_gone = 0;

        for (cp = pp->p_child_ns; cp != NULL; cp = cp->p_sibling_ns) {
            if (idtype != P_PID && (cp->p_pidflag & CLDWAITPID))
                continue;
            if (idtype == P_PID && id != cp->p_pid)
                continue;
            if (idtype == P_PGID && id != cp->p_pgrp)
                continue;

            switch (cp->p_wcode) {

            case CLD_TRAPPED:
            case CLD_STOPPED:
            case CLD_CONTINUED:
                cmn_err(CE_PANIC,
                    "waitid: wrong state %d on the p_newstate"
                    " list", cp->p_wcode);
                break;

            case CLD_EXITED:
            case CLD_DUMPED:
            case CLD_KILLED:
                if (!(options & WEXITED)) {
                    /*
                     * Count how many are already gone
                     * for good.
                     */
                    proc_gone++;
                    break;
                }
                if (!waitflag) {
                    winfo(cp, ip, 0);
                } else {
                    winfo(cp, ip, 1);
                    freeproc(cp);
                }
                mutex_exit(&pidlock);
                if (waitflag) {     /* accept SIGCLD */
                    sigcld_delete(ip);
                    sigcld_repost();
                }
                return (0);
            }

            if (idtype == P_PID)
                break;
        }

        /*
         * Wow! None of the threads on the p_sibling_ns list were
         * interesting threads. Check all the kids!
         */
        found = 0;
        for (cp = pp->p_child; cp != NULL; cp = cp->p_sibling) {
            if (idtype == P_PID && id != cp->p_pid)
                continue;
            if (idtype == P_PGID && id != cp->p_pgrp)
                continue;

            switch (cp->p_wcode) {
            case CLD_TRAPPED:
                if (!(options & WTRAPPED))
                    break;
                winfo(cp, ip, waitflag);
                mutex_exit(&pidlock);
                if (waitflag) {     /* accept SIGCLD */
                    sigcld_delete(ip);
                    sigcld_repost();
                }
                return (0);

            case CLD_STOPPED:
                if (!(options & WSTOPPED))
                    break;
                /* Is it still stopped? */
                mutex_enter(&cp->p_lock);
                if (!jobstopped(cp)) {
                    mutex_exit(&cp->p_lock);
                    break;
                }
                mutex_exit(&cp->p_lock);
                winfo(cp, ip, waitflag);
                mutex_exit(&pidlock);
                if (waitflag) {     /* accept SIGCLD */
                    sigcld_delete(ip);
                    sigcld_repost();
                }
                return (0);

            case CLD_CONTINUED:
                if (!(options & WCONTINUED))
                    break;
                winfo(cp, ip, waitflag);
                mutex_exit(&pidlock);
                if (waitflag) {     /* accept SIGCLD */
                    sigcld_delete(ip);
                    sigcld_repost();
                }
                return (0);

            case CLD_EXITED:
            case CLD_DUMPED:
            case CLD_KILLED:
                if (idtype != P_PID &&
                    (cp->p_pidflag & CLDWAITPID))
                    continue;
                /*
                 * Don't complain if a process was found in
                 * the first loop but we broke out of the loop
                 * because of the arguments passed to us.
                 */
                if (proc_gone == 0) {
                    cmn_err(CE_PANIC,
                        "waitid: wrong state on the"
                        " p_child list");
                } else {
                    break;
                }
            }

            found++;

            if (idtype == P_PID)
                break;
        }

        /*
         * If we found no interesting processes at all,
         * break out and return ECHILD.
         */
        if (found + proc_gone == 0)
            break;

        if (options & WNOHANG) {
            mutex_exit(&pidlock);
            bzero(ip, sizeof (k_siginfo_t));
            /*
             * We should set ip->si_signo = SIGCLD,
             * but there is an SVVS test that expects
             * ip->si_signo to be zero in this case.
             */
            return (0);
        }

        /*
         * If we found no processes of interest that could
         * change state while we wait, we don't wait at all.
         * Get out with ECHILD according to SVID.
         */
        if (found == proc_gone)
            break;

        if (!cv_wait_sig_swap(&pp->p_cv, &pidlock)) {
            mutex_exit(&pidlock);
            return (EINTR);
        }
    }
    mutex_exit(&pidlock);
    return (ECHILD);
}

int
waitsys(idtype_t idtype, id_t id, siginfo_t *infop, int options)
{
    int error;
    k_siginfo_t info;

    if (error = waitid(idtype, id, &info, options))
        return (set_errno(error));
    if (copyout(&info, infop, sizeof (k_siginfo_t)))
        return (set_errno(EFAULT));
    return (0);
}

#ifdef _SYSCALL32_IMPL

int
waitsys32(idtype_t idtype, id_t id, siginfo_t *infop, int options)
{
    int error;
    k_siginfo_t info;
    siginfo32_t info32;

    if (error = waitid(idtype, id, &info, options))
        return (set_errno(error));
    siginfo_kto32(&info, &info32);
    if (copyout(&info32, infop, sizeof (info32)))
        return (set_errno(EFAULT));
    return (0);
}

#endif  /* _SYSCALL32_IMPL */

void
proc_detach(proc_t *p)
{
    proc_t *q;

    ASSERT(MUTEX_HELD(&pidlock));

    q = p->p_parent;
    ASSERT(q != NULL);

    /*
     * Take it off the newstate list of its parent
     */
    delete_ns(q, p);

    if (q->p_child == p) {
        q->p_child = p->p_sibling;
        /*
         * If the parent has no children, it better not
         * have any with new states either!
         */
        ASSERT(q->p_child ? 1 : q->p_child_ns == NULL);
    }

    if (p->p_sibling) {
        p->p_sibling->p_psibling = p->p_psibling;
    }

    if (p->p_psibling) {
        p->p_psibling->p_sibling = p->p_sibling;
    }
}

/*
 * Remove zombie children from the process table.
 */
void
freeproc(proc_t *p)
{
    proc_t *q;

    ASSERT(p->p_stat == SZOMB);
    ASSERT(p->p_tlist == NULL);
    ASSERT(MUTEX_HELD(&pidlock));

    sigdelq(p, NULL, 0);
    if (p->p_killsqp) {
        siginfofree(p->p_killsqp);
        p->p_killsqp = NULL;
    }

    prfree(p);  /* inform /proc */

    /*
     * Don't free the init processes.
     * Other dying processes will access it.
     */
    if (p == proc_init)
        return;


    /*
     * We wait until now to free the cred structure because a
     * zombie process's credentials may be examined by /proc.
     * No cred locking needed because there are no threads at this point.
     */
    upcount_dec(crgetruid(p->p_cred), crgetzoneid(p->p_cred));
    crfree(p->p_cred);
    if (p->p_corefile != NULL) {
        corectl_path_rele(p->p_corefile);
        p->p_corefile = NULL;
    }
    if (p->p_content != NULL) {
        corectl_content_rele(p->p_content);
        p->p_content = NULL;
    }

    if (p->p_nextofkin && !((p->p_nextofkin->p_flag & SNOWAIT) ||
        (PTOU(p->p_nextofkin)->u_signal[SIGCLD - 1] == SIG_IGN))) {
        /*
         * This should still do the right thing since p_utime/stime
         * get set to the correct value on process exit, so it
         * should get properly updated
         */
        p->p_nextofkin->p_cutime += p->p_utime;
        p->p_nextofkin->p_cstime += p->p_stime;

        p->p_nextofkin->p_cacct[LMS_USER] += p->p_acct[LMS_USER];
        p->p_nextofkin->p_cacct[LMS_SYSTEM] += p->p_acct[LMS_SYSTEM];
        p->p_nextofkin->p_cacct[LMS_TRAP] += p->p_acct[LMS_TRAP];
        p->p_nextofkin->p_cacct[LMS_TFAULT] += p->p_acct[LMS_TFAULT];
        p->p_nextofkin->p_cacct[LMS_DFAULT] += p->p_acct[LMS_DFAULT];
        p->p_nextofkin->p_cacct[LMS_KFAULT] += p->p_acct[LMS_KFAULT];
        p->p_nextofkin->p_cacct[LMS_USER_LOCK]
            += p->p_acct[LMS_USER_LOCK];
        p->p_nextofkin->p_cacct[LMS_SLEEP] += p->p_acct[LMS_SLEEP];
        p->p_nextofkin->p_cacct[LMS_WAIT_CPU]
            += p->p_acct[LMS_WAIT_CPU];
        p->p_nextofkin->p_cacct[LMS_STOPPED] += p->p_acct[LMS_STOPPED];

        p->p_nextofkin->p_cru.minflt    += p->p_ru.minflt;
        p->p_nextofkin->p_cru.majflt    += p->p_ru.majflt;
        p->p_nextofkin->p_cru.nswap += p->p_ru.nswap;
        p->p_nextofkin->p_cru.inblock   += p->p_ru.inblock;
        p->p_nextofkin->p_cru.oublock   += p->p_ru.oublock;
        p->p_nextofkin->p_cru.msgsnd    += p->p_ru.msgsnd;
        p->p_nextofkin->p_cru.msgrcv    += p->p_ru.msgrcv;
        p->p_nextofkin->p_cru.nsignals  += p->p_ru.nsignals;
        p->p_nextofkin->p_cru.nvcsw += p->p_ru.nvcsw;
        p->p_nextofkin->p_cru.nivcsw    += p->p_ru.nivcsw;
        p->p_nextofkin->p_cru.sysc  += p->p_ru.sysc;
        p->p_nextofkin->p_cru.ioch  += p->p_ru.ioch;

    }

    q = p->p_nextofkin;
    if (q && q->p_orphan == p)
        q->p_orphan = p->p_nextorph;
    else if (q) {
        for (q = q->p_orphan; q; q = q->p_nextorph)
            if (q->p_nextorph == p)
                break;
        ASSERT(q && q->p_nextorph == p);
        q->p_nextorph = p->p_nextorph;
    }

    proc_detach(p);
    pid_exit(p);    /* frees pid and proc structure */
}

/*
 * Delete process "child" from the newstate list of process "parent"
 */
void
delete_ns(proc_t *parent, proc_t *child)
{
    proc_t **ns;

    ASSERT(MUTEX_HELD(&pidlock));
    ASSERT(child->p_parent == parent);
    for (ns = &parent->p_child_ns; *ns != NULL; ns = &(*ns)->p_sibling_ns) {
        if (*ns == child) {

            ASSERT((*ns)->p_parent == parent);

            *ns = child->p_sibling_ns;
            child->p_sibling_ns = NULL;
            return;
        }
    }
}

/*
 * Add process "child" to the new state list of process "parent"
 */
void
add_ns(proc_t *parent, proc_t *child)
{
    ASSERT(child->p_sibling_ns == NULL);
    child->p_sibling_ns = parent->p_child_ns;
    parent->p_child_ns = child;
}