port/aio/aio.c

	aio.c revision 4d86dd30d2f1154ded30a45ac7c3a29f7febabac
/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include "synonyms.h"
#include "thr_uberdata.h"
#include "asyncio.h"
#include <atomic.h>
#include <sys/param.h>
#include <sys/file.h>
#include <sys/port.h>

static int _aio_hash_insert(aio_result_t *, aio_req_t *);
static aio_req_t *_aio_req_get(aio_worker_t *);
static void _aio_req_add(aio_req_t *, aio_worker_t **, int);
static void _aio_req_del(aio_worker_t *, aio_req_t *, int);
static void _aio_work_done(aio_worker_t *);
static void _aio_enq_doneq(aio_req_t *);

extern void _aio_lio_free(aio_lio_t *);

extern int __fdsync(int, int);
extern int __fcntl(int, int, ...);
extern int _port_dispatch(int, int, int, int, uintptr_t, void *);

static int _aio_fsync_del(aio_worker_t *, aio_req_t *);
static void _aiodone(aio_req_t *, ssize_t, int);
static void _aio_cancel_work(aio_worker_t *, int, int *, int *);
static void _aio_finish_request(aio_worker_t *, ssize_t, int);

/*
 * switch for kernel async I/O
 */
int _kaio_ok = 0;       /* 0 = disabled, 1 = on, -1 = error */

/*
 * Key for thread-specific data
 */
pthread_key_t _aio_key;

/*
 * Array for determining whether or not a file supports kaio.
 * Initialized in _kaio_init().
 */
uint32_t *_kaio_supported = NULL;

/*
 *  workers for read/write requests
 * (__aio_mutex lock protects circular linked list of workers)
 */
aio_worker_t *__workers_rw; /* circular list of AIO workers */
aio_worker_t *__nextworker_rw;  /* next worker in list of workers */
int __rw_workerscnt;        /* number of read/write workers */

/*
 * worker for notification requests.
 */
aio_worker_t *__workers_no; /* circular list of AIO workers */
aio_worker_t *__nextworker_no;  /* next worker in list of workers */
int __no_workerscnt;        /* number of write workers */

aio_req_t *_aio_done_tail;      /* list of done requests */
aio_req_t *_aio_done_head;

mutex_t __aio_initlock = DEFAULTMUTEX;  /* makes aio initialization atomic */
cond_t __aio_initcv = DEFAULTCV;
int __aio_initbusy = 0;

mutex_t __aio_mutex = DEFAULTMUTEX; /* protects counts, and linked lists */
cond_t _aio_iowait_cv = DEFAULTCV;  /* wait for userland I/Os */

pid_t __pid = (pid_t)-1;        /* initialize as invalid pid */
int _sigio_enabled = 0;         /* when set, send SIGIO signal */

aio_hash_t *_aio_hash;

aio_req_t *_aio_doneq;          /* double linked done queue list */

int _aio_donecnt = 0;
int _aio_waitncnt = 0;          /* # of requests for aio_waitn */
int _aio_doneq_cnt = 0;
int _aio_outstand_cnt = 0;      /* # of outstanding requests */
int _kaio_outstand_cnt = 0;     /* # of outstanding kaio requests */
int _aio_req_done_cnt = 0;      /* req. done but not in "done queue" */
int _aio_kernel_suspend = 0;        /* active kernel kaio calls */
int _aio_suscv_cnt = 0;         /* aio_suspend calls waiting on cv's */

int _max_workers = 256;         /* max number of workers permitted */
int _min_workers = 4;           /* min number of workers */
int _minworkload = 2;           /* min number of request in q */
int _aio_worker_cnt = 0;        /* number of workers to do requests */
int __uaio_ok = 0;          /* AIO has been enabled */
sigset_t _worker_set;           /* worker's signal mask */

int _aiowait_flag = 0;          /* when set, aiowait() is inprogress */
int _aio_flags = 0;         /* see asyncio.h defines for */

aio_worker_t *_kaiowp = NULL;       /* points to kaio cleanup thread */

int hz;                 /* clock ticks per second */

static int
_kaio_supported_init(void)
{
    void *ptr;
    size_t size;

    if (_kaio_supported != NULL)    /* already initialized */
        return (0);

    size = MAX_KAIO_FDARRAY_SIZE * sizeof (uint32_t);
    ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
        MAP_PRIVATE | MAP_ANON, -1, (off_t)0);
    if (ptr == MAP_FAILED)
        return (-1);
    _kaio_supported = ptr;
    return (0);
}

/*
 * The aio subsystem is initialized when an AIO request is made.
 * Constants are initialized like the max number of workers that
 * the subsystem can create, and the minimum number of workers
 * permitted before imposing some restrictions.  Also, some
 * workers are created.
 */
int
__uaio_init(void)
{
    int ret = -1;
    int i;
    int cancel_state;

    lmutex_lock(&__aio_initlock);
    (void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancel_state);
    while (__aio_initbusy)
        (void) cond_wait(&__aio_initcv, &__aio_initlock);
    (void) pthread_setcancelstate(cancel_state, NULL);
    if (__uaio_ok) {    /* already initialized */
        lmutex_unlock(&__aio_initlock);
        return (0);
    }
    __aio_initbusy = 1;
    lmutex_unlock(&__aio_initlock);

    hz = (int)sysconf(_SC_CLK_TCK);
    __pid = getpid();

    setup_cancelsig(SIGAIOCANCEL);

    if (_kaio_supported_init() != 0)
        goto out;

    /*
     * Allocate and initialize the hash table.
     * Do this only once, even if __uaio_init() is called twice.
     */
    if (_aio_hash == NULL) {
        /* LINTED pointer cast */
        _aio_hash = (aio_hash_t *)mmap(NULL,
            HASHSZ * sizeof (aio_hash_t), PROT_READ | PROT_WRITE,
            MAP_PRIVATE | MAP_ANON, -1, (off_t)0);
        if ((void *)_aio_hash == MAP_FAILED) {
            _aio_hash = NULL;
            goto out;
        }
        for (i = 0; i < HASHSZ; i++)
            (void) mutex_init(&_aio_hash[i].hash_lock,
                USYNC_THREAD, NULL);
    }

    /*
     * Initialize worker's signal mask to only catch SIGAIOCANCEL.
     */
    (void) sigfillset(&_worker_set);
    (void) sigdelset(&_worker_set, SIGAIOCANCEL);

    /*
     * Create one worker to send asynchronous notifications.
     * Do this only once, even if __uaio_init() is called twice.
     */
    if (__no_workerscnt == 0 &&
        (_aio_create_worker(NULL, AIONOTIFY) != 0)) {
        errno = EAGAIN;
        goto out;
    }

    /*
     * Create the minimum number of read/write workers.
     * And later check whether atleast one worker is created;
     * lwp_create() calls could fail because of segkp exhaustion.
     */
    for (i = 0; i < _min_workers; i++)
        (void) _aio_create_worker(NULL, AIOREAD);
    if (__rw_workerscnt == 0) {
        errno = EAGAIN;
        goto out;
    }

    ret = 0;
out:
    lmutex_lock(&__aio_initlock);
    if (ret == 0)
        __uaio_ok = 1;
    __aio_initbusy = 0;
    (void) cond_broadcast(&__aio_initcv);
    lmutex_unlock(&__aio_initlock);
    return (ret);
}

/*
 * Called from close() before actually performing the real _close().
 */
void
_aio_close(int fd)
{
    if (fd < 0) /* avoid cancelling everything */
        return;
    /*
     * Cancel all outstanding aio requests for this file descriptor.
     */
    if (__uaio_ok)
        (void) aiocancel_all(fd);
    /*
     * If we have allocated the bit array, clear the bit for this file.
     * The next open may re-use this file descriptor and the new file
     * may have different kaio() behaviour.
     */
    if (_kaio_supported != NULL)
        CLEAR_KAIO_SUPPORTED(fd);
}

/*
 * special kaio cleanup thread sits in a loop in the
 * kernel waiting for pending kaio requests to complete.
 */
void *
_kaio_cleanup_thread(void *arg)
{
    if (pthread_setspecific(_aio_key, arg) != 0)
        aio_panic("_kaio_cleanup_thread, pthread_setspecific()");
    (void) _kaio(AIOSTART);
    return (arg);
}

/*
 * initialize kaio.
 */
void
_kaio_init()
{
    int error;
    sigset_t oset;
    int cancel_state;

    lmutex_lock(&__aio_initlock);
    (void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancel_state);
    while (__aio_initbusy)
        (void) cond_wait(&__aio_initcv, &__aio_initlock);
    (void) pthread_setcancelstate(cancel_state, NULL);
    if (_kaio_ok) {     /* already initialized */
        lmutex_unlock(&__aio_initlock);
        return;
    }
    __aio_initbusy = 1;
    lmutex_unlock(&__aio_initlock);

    if (_kaio_supported_init() != 0)
        error = ENOMEM;
    else if ((_kaiowp = _aio_worker_alloc()) == NULL)
        error = ENOMEM;
    else if ((error = (int)_kaio(AIOINIT)) == 0) {
        (void) pthread_sigmask(SIG_SETMASK, &maskset, &oset);
        error = thr_create(NULL, AIOSTKSIZE, _kaio_cleanup_thread,
            _kaiowp, THR_DAEMON, &_kaiowp->work_tid);
        (void) pthread_sigmask(SIG_SETMASK, &oset, NULL);
    }
    if (error && _kaiowp != NULL) {
        _aio_worker_free(_kaiowp);
        _kaiowp = NULL;
    }

    lmutex_lock(&__aio_initlock);
    if (error)
        _kaio_ok = -1;
    else
        _kaio_ok = 1;
    __aio_initbusy = 0;
    (void) cond_broadcast(&__aio_initcv);
    lmutex_unlock(&__aio_initlock);
}

int
aioread(int fd, caddr_t buf, int bufsz, off_t offset, int whence,
    aio_result_t *resultp)
{
    return (_aiorw(fd, buf, bufsz, offset, whence, resultp, AIOREAD));
}

int
aiowrite(int fd, caddr_t buf, int bufsz, off_t offset, int whence,
    aio_result_t *resultp)
{
    return (_aiorw(fd, buf, bufsz, offset, whence, resultp, AIOWRITE));
}

#if !defined(_LP64)
int
aioread64(int fd, caddr_t buf, int bufsz, off64_t offset, int whence,
    aio_result_t *resultp)
{
    return (_aiorw(fd, buf, bufsz, offset, whence, resultp, AIOAREAD64));
}

int
aiowrite64(int fd, caddr_t buf, int bufsz, off64_t offset, int whence,
    aio_result_t *resultp)
{
    return (_aiorw(fd, buf, bufsz, offset, whence, resultp, AIOAWRITE64));
}
#endif  /* !defined(_LP64) */

int
_aiorw(int fd, caddr_t buf, int bufsz, offset_t offset, int whence,
    aio_result_t *resultp, int mode)
{
    aio_req_t *reqp;
    aio_args_t *ap;
    offset_t loffset;
    struct stat64 stat64;
    int error = 0;
    int kerr;
    int umode;

    switch (whence) {

    case SEEK_SET:
        loffset = offset;
        break;
    case SEEK_CUR:
        if ((loffset = llseek(fd, 0, SEEK_CUR)) == -1)
            error = -1;
        else
            loffset += offset;
        break;
    case SEEK_END:
        if (fstat64(fd, &stat64) == -1)
            error = -1;
        else
            loffset = offset + stat64.st_size;
        break;
    default:
        errno = EINVAL;
        error = -1;
    }

    if (error)
        return (error);

    /* initialize kaio */
    if (!_kaio_ok)
        _kaio_init();

    /*
     * _aio_do_request() needs the original request code (mode) to be able
     * to choose the appropiate 32/64 bit function.  All other functions
     * only require the difference between READ and WRITE (umode).
     */
    if (mode == AIOAREAD64 || mode == AIOAWRITE64)
        umode = mode - AIOAREAD64;
    else
        umode = mode;

    /*
     * Try kernel aio first.
     * If errno is ENOTSUP/EBADFD, fall back to the thread implementation.
     */
    if (_kaio_ok > 0 && KAIO_SUPPORTED(fd)) {
        resultp->aio_errno = 0;
        sig_mutex_lock(&__aio_mutex);
        _kaio_outstand_cnt++;
        sig_mutex_unlock(&__aio_mutex);
        kerr = (int)_kaio(((resultp->aio_return == AIO_INPROGRESS) ?
            (umode | AIO_POLL_BIT) : umode),
            fd, buf, bufsz, loffset, resultp);
        if (kerr == 0) {
            return (0);
        }
        sig_mutex_lock(&__aio_mutex);
        _kaio_outstand_cnt--;
        sig_mutex_unlock(&__aio_mutex);
        if (errno != ENOTSUP && errno != EBADFD)
            return (-1);
        if (errno == EBADFD)
            SET_KAIO_NOT_SUPPORTED(fd);
    }

    if (!__uaio_ok && __uaio_init() == -1)
        return (-1);

    if ((reqp = _aio_req_alloc()) == NULL) {
        errno = EAGAIN;
        return (-1);
    }

    /*
     * _aio_do_request() checks reqp->req_op to differentiate
     * between 32 and 64 bit access.
     */
    reqp->req_op = mode;
    reqp->req_resultp = resultp;
    ap = &reqp->req_args;
    ap->fd = fd;
    ap->buf = buf;
    ap->bufsz = bufsz;
    ap->offset = loffset;

    if (_aio_hash_insert(resultp, reqp) != 0) {
        _aio_req_free(reqp);
        errno = EINVAL;
        return (-1);
    }
    /*
     * _aio_req_add() only needs the difference between READ and
     * WRITE to choose the right worker queue.
     */
    _aio_req_add(reqp, &__nextworker_rw, umode);
    return (0);
}

int
aiocancel(aio_result_t *resultp)
{
    aio_req_t *reqp;
    aio_worker_t *aiowp;
    int ret;
    int done = 0;
    int canceled = 0;

    if (!__uaio_ok) {
        errno = EINVAL;
        return (-1);
    }

    sig_mutex_lock(&__aio_mutex);
    reqp = _aio_hash_find(resultp);
    if (reqp == NULL) {
        if (_aio_outstand_cnt == _aio_req_done_cnt)
            errno = EINVAL;
        else
            errno = EACCES;
        ret = -1;
    } else {
        aiowp = reqp->req_worker;
        sig_mutex_lock(&aiowp->work_qlock1);
        (void) _aio_cancel_req(aiowp, reqp, &canceled, &done);
        sig_mutex_unlock(&aiowp->work_qlock1);

        if (canceled) {
            ret = 0;
        } else {
            if (_aio_outstand_cnt == 0 ||
                _aio_outstand_cnt == _aio_req_done_cnt)
                errno = EINVAL;
            else
                errno = EACCES;
            ret = -1;
        }
    }
    sig_mutex_unlock(&__aio_mutex);
    return (ret);
}

/* ARGSUSED */
static void
_aiowait_cleanup(void *arg)
{
    sig_mutex_lock(&__aio_mutex);
    _aiowait_flag--;
    sig_mutex_unlock(&__aio_mutex);
}

/*
 * This must be asynch safe and cancel safe
 */
aio_result_t *
aiowait(struct timeval *uwait)
{
    aio_result_t *uresultp;
    aio_result_t *kresultp;
    aio_result_t *resultp;
    int dontblock;
    int timedwait = 0;
    int kaio_errno = 0;
    struct timeval twait;
    struct timeval *wait = NULL;
    hrtime_t hrtend;
    hrtime_t hres;

    if (uwait) {
        /*
         * Check for a valid specified wait time.
         * If it is invalid, fail the call right away.
         */
        if (uwait->tv_sec < 0 || uwait->tv_usec < 0 ||
            uwait->tv_usec >= MICROSEC) {
            errno = EINVAL;
            return ((aio_result_t *)-1);
        }

        if (uwait->tv_sec > 0 || uwait->tv_usec > 0) {
            hrtend = gethrtime() +
                (hrtime_t)uwait->tv_sec * NANOSEC +
                (hrtime_t)uwait->tv_usec * (NANOSEC / MICROSEC);
            twait = *uwait;
            wait = &twait;
            timedwait++;
        } else {
            /* polling */
            sig_mutex_lock(&__aio_mutex);
            if (_kaio_outstand_cnt == 0) {
                kresultp = (aio_result_t *)-1;
            } else {
                kresultp = (aio_result_t *)_kaio(AIOWAIT,
                    (struct timeval *)-1, 1);
                if (kresultp != (aio_result_t *)-1 &&
                    kresultp != NULL &&
                    kresultp != (aio_result_t *)1) {
                    _kaio_outstand_cnt--;
                    sig_mutex_unlock(&__aio_mutex);
                    return (kresultp);
                }
            }
            uresultp = _aio_req_done();
            sig_mutex_unlock(&__aio_mutex);
            if (uresultp != NULL &&
                uresultp != (aio_result_t *)-1) {
                return (uresultp);
            }
            if (uresultp == (aio_result_t *)-1 &&
                kresultp == (aio_result_t *)-1) {
                errno = EINVAL;
                return ((aio_result_t *)-1);
            } else {
                return (NULL);
            }
        }
    }

    for (;;) {
        sig_mutex_lock(&__aio_mutex);
        uresultp = _aio_req_done();
        if (uresultp != NULL && uresultp != (aio_result_t *)-1) {
            sig_mutex_unlock(&__aio_mutex);
            resultp = uresultp;
            break;
        }
        _aiowait_flag++;
        dontblock = (uresultp == (aio_result_t *)-1);
        if (dontblock && _kaio_outstand_cnt == 0) {
            kresultp = (aio_result_t *)-1;
            kaio_errno = EINVAL;
        } else {
            sig_mutex_unlock(&__aio_mutex);
            pthread_cleanup_push(_aiowait_cleanup, NULL);
            _cancel_prologue();
            kresultp = (aio_result_t *)_kaio(AIOWAIT,
                wait, dontblock);
            _cancel_epilogue();
            pthread_cleanup_pop(0);
            sig_mutex_lock(&__aio_mutex);
            kaio_errno = errno;
        }
        _aiowait_flag--;
        sig_mutex_unlock(&__aio_mutex);
        if (kresultp == (aio_result_t *)1) {
            /* aiowait() awakened by an aionotify() */
            continue;
        } else if (kresultp != NULL &&
            kresultp != (aio_result_t *)-1) {
            resultp = kresultp;
            sig_mutex_lock(&__aio_mutex);
            _kaio_outstand_cnt--;
            sig_mutex_unlock(&__aio_mutex);
            break;
        } else if (kresultp == (aio_result_t *)-1 &&
            kaio_errno == EINVAL &&
            uresultp == (aio_result_t *)-1) {
            errno = kaio_errno;
            resultp = (aio_result_t *)-1;
            break;
        } else if (kresultp == (aio_result_t *)-1 &&
            kaio_errno == EINTR) {
            errno = kaio_errno;
            resultp = (aio_result_t *)-1;
            break;
        } else if (timedwait) {
            hres = hrtend - gethrtime();
            if (hres <= 0) {
                /* time is up; return */
                resultp = NULL;
                break;
            } else {
                /*
                 * Some time left.  Round up the remaining time
                 * in nanoseconds to microsec.  Retry the call.
                 */
                hres += (NANOSEC / MICROSEC) - 1;
                wait->tv_sec = hres / NANOSEC;
                wait->tv_usec =
                    (hres % NANOSEC) / (NANOSEC / MICROSEC);
            }
        } else {
            ASSERT(kresultp == NULL && uresultp == NULL);
            resultp = NULL;
            continue;
        }
    }
    return (resultp);
}

/*
 * _aio_get_timedelta calculates the remaining time and stores the result
 * into timespec_t *wait.
 */

int
_aio_get_timedelta(timespec_t *end, timespec_t *wait)
{
    int ret = 0;
    struct  timeval cur;
    timespec_t curtime;

    (void) gettimeofday(&cur, NULL);
    curtime.tv_sec = cur.tv_sec;
    curtime.tv_nsec = cur.tv_usec * 1000;   /* convert us to ns */

    if (end->tv_sec >= curtime.tv_sec) {
        wait->tv_sec = end->tv_sec - curtime.tv_sec;
        if (end->tv_nsec >= curtime.tv_nsec) {
            wait->tv_nsec = end->tv_nsec - curtime.tv_nsec;
            if (wait->tv_sec == 0 && wait->tv_nsec == 0)
                ret = -1;   /* timer expired */
        } else {
            if (end->tv_sec > curtime.tv_sec) {
                wait->tv_sec -= 1;
                wait->tv_nsec = NANOSEC -
                    (curtime.tv_nsec - end->tv_nsec);
            } else {
                ret = -1;   /* timer expired */
            }
        }
    } else {
        ret = -1;
    }
    return (ret);
}

/*
 * If closing by file descriptor: we will simply cancel all the outstanding
 * aio`s and return.  Those aio's in question will have either noticed the
 * cancellation notice before, during, or after initiating io.
 */
int
aiocancel_all(int fd)
{
    aio_req_t *reqp;
    aio_req_t **reqpp;
    aio_worker_t *first;
    aio_worker_t *next;
    int canceled = 0;
    int done = 0;
    int cancelall = 0;

    sig_mutex_lock(&__aio_mutex);

    if (_aio_outstand_cnt == 0) {
        sig_mutex_unlock(&__aio_mutex);
        return (AIO_ALLDONE);
    }

    /*
     * Cancel requests from the read/write workers' queues.
     */
    first = __nextworker_rw;
    next = first;
    do {
        _aio_cancel_work(next, fd, &canceled, &done);
    } while ((next = next->work_forw) != first);

    /*
     * finally, check if there are requests on the done queue that
     * should be canceled.
     */
    if (fd < 0)
        cancelall = 1;
    reqpp = &_aio_done_tail;
    while ((reqp = *reqpp) != NULL) {
        if (cancelall || reqp->req_args.fd == fd) {
            *reqpp = reqp->req_next;
            _aio_donecnt--;
            (void) _aio_hash_del(reqp->req_resultp);
            _aio_req_free(reqp);
        } else
            reqpp = &reqp->req_next;
    }
    if (cancelall) {
        ASSERT(_aio_donecnt == 0);
        _aio_done_head = NULL;
    }
    sig_mutex_unlock(&__aio_mutex);

    if (canceled && done == 0)
        return (AIO_CANCELED);
    else if (done && canceled == 0)
        return (AIO_ALLDONE);
    else if ((canceled + done == 0) && KAIO_SUPPORTED(fd))
        return ((int)_kaio(AIOCANCEL, fd, NULL));
    return (AIO_NOTCANCELED);
}

/*
 * Cancel requests from a given work queue.  If the file descriptor
 * parameter, fd, is non-negative, then only cancel those requests
 * in this queue that are to this file descriptor.  If the fd
 * parameter is -1, then cancel all requests.
 */
static void
_aio_cancel_work(aio_worker_t *aiowp, int fd, int *canceled, int *done)
{
    aio_req_t *reqp;

    sig_mutex_lock(&aiowp->work_qlock1);
    /*
     * cancel queued requests first.
     */
    reqp = aiowp->work_tail1;
    while (reqp != NULL) {
        if (fd < 0 || reqp->req_args.fd == fd) {
            if (_aio_cancel_req(aiowp, reqp, canceled, done)) {
                /*
                 * Callers locks were dropped.
                 * reqp is invalid; start traversing
                 * the list from the beginning again.
                 */
                reqp = aiowp->work_tail1;
                continue;
            }
        }
        reqp = reqp->req_next;
    }
    /*
     * Since the queued requests have been canceled, there can
     * only be one inprogress request that should be canceled.
     */
    if ((reqp = aiowp->work_req) != NULL &&
        (fd < 0 || reqp->req_args.fd == fd))
        (void) _aio_cancel_req(aiowp, reqp, canceled, done);
    sig_mutex_unlock(&aiowp->work_qlock1);
}

/*
 * Cancel a request.  Return 1 if the callers locks were temporarily
 * dropped, otherwise return 0.
 */
int
_aio_cancel_req(aio_worker_t *aiowp, aio_req_t *reqp, int *canceled, int *done)
{
    int ostate = reqp->req_state;

    ASSERT(MUTEX_HELD(&__aio_mutex));
    ASSERT(MUTEX_HELD(&aiowp->work_qlock1));
    if (ostate == AIO_REQ_CANCELED)
        return (0);
    if (ostate == AIO_REQ_DONE || ostate == AIO_REQ_DONEQ) {
        (*done)++;
        return (0);
    }
    if (reqp->req_op == AIOFSYNC && reqp != aiowp->work_req) {
        ASSERT(POSIX_AIO(reqp));
        /* Cancel the queued aio_fsync() request */
        if (!reqp->req_head->lio_canned) {
            reqp->req_head->lio_canned = 1;
            _aio_outstand_cnt--;
            (*canceled)++;
        }
        return (0);
    }
    reqp->req_state = AIO_REQ_CANCELED;
    _aio_req_del(aiowp, reqp, ostate);
    (void) _aio_hash_del(reqp->req_resultp);
    (*canceled)++;
    if (reqp == aiowp->work_req) {
        ASSERT(ostate == AIO_REQ_INPROGRESS);
        /*
         * Set the result values now, before _aiodone() is called.
         * We do this because the application can expect aio_return
         * and aio_errno to be set to -1 and ECANCELED, respectively,
         * immediately after a successful return from aiocancel()
         * or aio_cancel().
         */
        _aio_set_result(reqp, -1, ECANCELED);
        (void) thr_kill(aiowp->work_tid, SIGAIOCANCEL);
        return (0);
    }
    if (!POSIX_AIO(reqp)) {
        _aio_outstand_cnt--;
        _aio_set_result(reqp, -1, ECANCELED);
        return (0);
    }
    sig_mutex_unlock(&aiowp->work_qlock1);
    sig_mutex_unlock(&__aio_mutex);
    _aiodone(reqp, -1, ECANCELED);
    sig_mutex_lock(&__aio_mutex);
    sig_mutex_lock(&aiowp->work_qlock1);
    return (1);
}

int
_aio_create_worker(aio_req_t *reqp, int mode)
{
    aio_worker_t *aiowp, **workers, **nextworker;
    int *aio_workerscnt;
    void *(*func)(void *);
    sigset_t oset;
    int error;

    /*
     * Put the new worker thread in the right queue.
     */
    switch (mode) {
    case AIOREAD:
    case AIOWRITE:
    case AIOAREAD:
    case AIOAWRITE:
#if !defined(_LP64)
    case AIOAREAD64:
    case AIOAWRITE64:
#endif
        workers = &__workers_rw;
        nextworker = &__nextworker_rw;
        aio_workerscnt = &__rw_workerscnt;
        func = _aio_do_request;
        break;
    case AIONOTIFY:
        workers = &__workers_no;
        nextworker = &__nextworker_no;
        func = _aio_do_notify;
        aio_workerscnt = &__no_workerscnt;
        break;
    default:
        aio_panic("_aio_create_worker: invalid mode");
        break;
    }

    if ((aiowp = _aio_worker_alloc()) == NULL)
        return (-1);

    if (reqp) {
        reqp->req_state = AIO_REQ_QUEUED;
        reqp->req_worker = aiowp;
        aiowp->work_head1 = reqp;
        aiowp->work_tail1 = reqp;
        aiowp->work_next1 = reqp;
        aiowp->work_count1 = 1;
        aiowp->work_minload1 = 1;
    }

    (void) pthread_sigmask(SIG_SETMASK, &maskset, &oset);
    error = thr_create(NULL, AIOSTKSIZE, func, aiowp,
        THR_DAEMON | THR_SUSPENDED, &aiowp->work_tid);
    (void) pthread_sigmask(SIG_SETMASK, &oset, NULL);
    if (error) {
        if (reqp) {
            reqp->req_state = 0;
            reqp->req_worker = NULL;
        }
        _aio_worker_free(aiowp);
        return (-1);
    }

    lmutex_lock(&__aio_mutex);
    (*aio_workerscnt)++;
    if (*workers == NULL) {
        aiowp->work_forw = aiowp;
        aiowp->work_backw = aiowp;
        *nextworker = aiowp;
        *workers = aiowp;
    } else {
        aiowp->work_backw = (*workers)->work_backw;
        aiowp->work_forw = (*workers);
        (*workers)->work_backw->work_forw = aiowp;
        (*workers)->work_backw = aiowp;
    }
    _aio_worker_cnt++;
    lmutex_unlock(&__aio_mutex);

    (void) thr_continue(aiowp->work_tid);

    return (0);
}

/*
 * This is the worker's main routine.
 * The task of this function is to execute all queued requests;
 * once the last pending request is executed this function will block
 * in _aio_idle().  A new incoming request must wakeup this thread to
 * restart the work.
 * Every worker has an own work queue.  The queue lock is required
 * to synchronize the addition of new requests for this worker or
 * cancellation of pending/running requests.
 *
 * Cancellation scenarios:
 * The cancellation of a request is being done asynchronously using
 * _aio_cancel_req() from another thread context.
 * A queued request can be cancelled in different manners :
 * a) request is queued but not "in progress" or "done" (AIO_REQ_QUEUED):
 *  - lock the queue -> remove the request -> unlock the queue
 *  - this function/thread does not detect this cancellation process
 * b) request is in progress (AIO_REQ_INPROGRESS) :
 *  - this function first allow the cancellation of the running
 *    request with the flag "work_cancel_flg=1"
 *      see _aio_req_get() -> _aio_cancel_on()
 *    During this phase, it is allowed to interrupt the worker
 *    thread running the request (this thread) using the SIGAIOCANCEL
 *    signal.
 *    Once this thread returns from the kernel (because the request
 *    is just done), then it must disable a possible cancellation
 *    and proceed to finish the request.  To disable the cancellation
 *    this thread must use _aio_cancel_off() to set "work_cancel_flg=0".
 * c) request is already done (AIO_REQ_DONE || AIO_REQ_DONEQ):
 *    same procedure as in a)
 *
 * To b)
 *  This thread uses sigsetjmp() to define the position in the code, where
 *  it wish to continue working in the case that a SIGAIOCANCEL signal
 *  is detected.
 *  Normally this thread should get the cancellation signal during the
 *  kernel phase (reading or writing).  In that case the signal handler
 *  aiosigcancelhndlr() is activated using the worker thread context,
 *  which again will use the siglongjmp() function to break the standard
 *  code flow and jump to the "sigsetjmp" position, provided that
 *  "work_cancel_flg" is set to "1".
 *  Because the "work_cancel_flg" is only manipulated by this worker
 *  thread and it can only run on one CPU at a given time, it is not
 *  necessary to protect that flag with the queue lock.
 *  Returning from the kernel (read or write system call) we must
 *  first disable the use of the SIGAIOCANCEL signal and accordingly
 *  the use of the siglongjmp() function to prevent a possible deadlock:
 *  - It can happens that this worker thread returns from the kernel and
 *    blocks in "work_qlock1",
 *  - then a second thread cancels the apparently "in progress" request
 *    and sends the SIGAIOCANCEL signal to the worker thread,
 *  - the worker thread gets assigned the "work_qlock1" and will returns
 *    from the kernel,
 *  - the kernel detects the pending signal and activates the signal
 *    handler instead,
 *  - if the "work_cancel_flg" is still set then the signal handler
 *    should use siglongjmp() to cancel the "in progress" request and
 *    it would try to acquire the same work_qlock1 in _aio_req_get()
 *    for a second time => deadlock.
 *  To avoid that situation we disable the cancellation of the request
 *  in progress BEFORE we try to acquire the work_qlock1.
 *  In that case the signal handler will not call siglongjmp() and the
 *  worker thread will continue running the standard code flow.
 *  Then this thread must check the AIO_REQ_CANCELED flag to emulate
 *  an eventually required siglongjmp() freeing the work_qlock1 and
 *  avoiding a deadlock.
 */
void *
_aio_do_request(void *arglist)
{
    aio_worker_t *aiowp = (aio_worker_t *)arglist;
    ulwp_t *self = curthread;
    struct aio_args *arg;
    aio_req_t *reqp;        /* current AIO request */
    ssize_t retval;
    int append;
    int error;

    if (pthread_setspecific(_aio_key, aiowp) != 0)
        aio_panic("_aio_do_request, pthread_setspecific()");
    (void) pthread_sigmask(SIG_SETMASK, &_worker_set, NULL);
    ASSERT(aiowp->work_req == NULL);

    /*
     * We resume here when an operation is cancelled.
     * On first entry, aiowp->work_req == NULL, so all
     * we do is block SIGAIOCANCEL.
     */
    (void) sigsetjmp(aiowp->work_jmp_buf, 0);
    ASSERT(self->ul_sigdefer == 0);

    sigoff(self);   /* block SIGAIOCANCEL */
    if (aiowp->work_req != NULL)
        _aio_finish_request(aiowp, -1, ECANCELED);

    for (;;) {
        /*
         * Put completed requests on aio_done_list.  This has
         * to be done as part of the main loop to ensure that
         * we don't artificially starve any aiowait'ers.
         */
        if (aiowp->work_done1)
            _aio_work_done(aiowp);

top:
        /* consume any deferred SIGAIOCANCEL signal here */
        sigon(self);
        sigoff(self);

        while ((reqp = _aio_req_get(aiowp)) == NULL) {
            if (_aio_idle(aiowp) != 0)
                goto top;
        }
        arg = &reqp->req_args;
        ASSERT(reqp->req_state == AIO_REQ_INPROGRESS ||
            reqp->req_state == AIO_REQ_CANCELED);
        error = 0;

        switch (reqp->req_op) {
        case AIOREAD:
        case AIOAREAD:
            sigon(self);    /* unblock SIGAIOCANCEL */
            retval = pread(arg->fd, arg->buf,
                arg->bufsz, arg->offset);
            if (retval == -1) {
                if (errno == ESPIPE) {
                    retval = read(arg->fd,
                        arg->buf, arg->bufsz);
                    if (retval == -1)
                        error = errno;
                } else {
                    error = errno;
                }
            }
            sigoff(self);   /* block SIGAIOCANCEL */
            break;
        case AIOWRITE:
        case AIOAWRITE:
            /*
             * The SUSv3 POSIX spec for aio_write() states:
             *  If O_APPEND is set for the file descriptor,
             *  write operations append to the file in the
             *  same order as the calls were made.
             * but, somewhat inconsistently, it requires pwrite()
             * to ignore the O_APPEND setting.  So we have to use
             * fcntl() to get the open modes and call write() for
             * the O_APPEND case.
             */
            append = (__fcntl(arg->fd, F_GETFL) & O_APPEND);
            sigon(self);    /* unblock SIGAIOCANCEL */
            retval = append?
                write(arg->fd, arg->buf, arg->bufsz) :
                pwrite(arg->fd, arg->buf, arg->bufsz,
                arg->offset);
            if (retval == -1) {
                if (errno == ESPIPE) {
                    retval = write(arg->fd,
                        arg->buf, arg->bufsz);
                    if (retval == -1)
                        error = errno;
                } else {
                    error = errno;
                }
            }
            sigoff(self);   /* block SIGAIOCANCEL */
            break;
#if !defined(_LP64)
        case AIOAREAD64:
            sigon(self);    /* unblock SIGAIOCANCEL */
            retval = pread64(arg->fd, arg->buf,
                arg->bufsz, arg->offset);
            if (retval == -1) {
                if (errno == ESPIPE) {
                    retval = read(arg->fd,
                        arg->buf, arg->bufsz);
                    if (retval == -1)
                        error = errno;
                } else {
                    error = errno;
                }
            }
            sigoff(self);   /* block SIGAIOCANCEL */
            break;
        case AIOAWRITE64:
            /*
             * The SUSv3 POSIX spec for aio_write() states:
             *  If O_APPEND is set for the file descriptor,
             *  write operations append to the file in the
             *  same order as the calls were made.
             * but, somewhat inconsistently, it requires pwrite()
             * to ignore the O_APPEND setting.  So we have to use
             * fcntl() to get the open modes and call write() for
             * the O_APPEND case.
             */
            append = (__fcntl(arg->fd, F_GETFL) & O_APPEND);
            sigon(self);    /* unblock SIGAIOCANCEL */
            retval = append?
                write(arg->fd, arg->buf, arg->bufsz) :
                pwrite64(arg->fd, arg->buf, arg->bufsz,
                arg->offset);
            if (retval == -1) {
                if (errno == ESPIPE) {
                    retval = write(arg->fd,
                        arg->buf, arg->bufsz);
                    if (retval == -1)
                        error = errno;
                } else {
                    error = errno;
                }
            }
            sigoff(self);   /* block SIGAIOCANCEL */
            break;
#endif  /* !defined(_LP64) */
        case AIOFSYNC:
            if (_aio_fsync_del(aiowp, reqp))
                goto top;
            ASSERT(reqp->req_head == NULL);
            /*
             * All writes for this fsync request are now
             * acknowledged.  Now make these writes visible
             * and put the final request into the hash table.
             */
            if (reqp->req_state == AIO_REQ_CANCELED) {
                /* EMPTY */;
            } else if (arg->offset == O_SYNC) {
                if ((retval = __fdsync(arg->fd, FSYNC)) == -1)
                    error = errno;
            } else {
                if ((retval = __fdsync(arg->fd, FDSYNC)) == -1)
                    error = errno;
            }
            if (_aio_hash_insert(reqp->req_resultp, reqp) != 0)
                aio_panic("_aio_do_request(): AIOFSYNC: "
                    "request already in hash table");
            break;
        default:
            aio_panic("_aio_do_request, bad op");
        }

        _aio_finish_request(aiowp, retval, error);
    }
    /* NOTREACHED */
    return (NULL);
}

/*
 * Perform the tail processing for _aio_do_request().
 * The in-progress request may or may not have been cancelled.
 */
static void
_aio_finish_request(aio_worker_t *aiowp, ssize_t retval, int error)
{
    aio_req_t *reqp;

    sig_mutex_lock(&aiowp->work_qlock1);
    if ((reqp = aiowp->work_req) == NULL)
        sig_mutex_unlock(&aiowp->work_qlock1);
    else {
        aiowp->work_req = NULL;
        if (reqp->req_state == AIO_REQ_CANCELED) {
            retval = -1;
            error = ECANCELED;
        }
        if (!POSIX_AIO(reqp)) {
            int notify;
            sig_mutex_unlock(&aiowp->work_qlock1);
            sig_mutex_lock(&__aio_mutex);
            if (reqp->req_state == AIO_REQ_INPROGRESS)
                reqp->req_state = AIO_REQ_DONE;
            /*
             * If it was canceled, this request will not be
             * added to done list. Just free it.
             */
            if (error == ECANCELED) {
                _aio_outstand_cnt--;
                _aio_req_free(reqp);
            } else {
                _aio_set_result(reqp, retval, error);
                _aio_req_done_cnt++;
            }
            /*
             * Notify any thread that may have blocked
             * because it saw an outstanding request.
             */
            notify = 0;
            if (_aio_outstand_cnt == 0 && _aiowait_flag) {
                notify = 1;
            }
            sig_mutex_unlock(&__aio_mutex);
            if (notify) {
                (void) _kaio(AIONOTIFY);
            }
        } else {
            if (reqp->req_state == AIO_REQ_INPROGRESS)
                reqp->req_state = AIO_REQ_DONE;
            sig_mutex_unlock(&aiowp->work_qlock1);
            _aiodone(reqp, retval, error);
        }
    }
}

void
_aio_req_mark_done(aio_req_t *reqp)
{
#if !defined(_LP64)
    if (reqp->req_largefile)
        ((aiocb64_t *)reqp->req_aiocbp)->aio_state = USERAIO_DONE;
    else
#endif
        ((aiocb_t *)reqp->req_aiocbp)->aio_state = USERAIO_DONE;
}

/*
 * Sleep for 'ticks' clock ticks to give somebody else a chance to run,
 * hopefully to consume one of our queued signals.
 */
static void
_aio_delay(int ticks)
{
    (void) usleep(ticks * (MICROSEC / hz));
}

/*
 * Actually send the notifications.
 * We could block indefinitely here if the application
 * is not listening for the signal or port notifications.
 */
static void
send_notification(notif_param_t *npp)
{
    extern int __sigqueue(pid_t pid, int signo,
        /* const union sigval */ void *value, int si_code, int block);

    if (npp->np_signo)
        (void) __sigqueue(__pid, npp->np_signo, npp->np_user,
            SI_ASYNCIO, 1);
    else if (npp->np_port >= 0)
        (void) _port_dispatch(npp->np_port, 0, PORT_SOURCE_AIO,
            npp->np_event, npp->np_object, npp->np_user);

    if (npp->np_lio_signo)
        (void) __sigqueue(__pid, npp->np_lio_signo, npp->np_lio_user,
            SI_ASYNCIO, 1);
    else if (npp->np_lio_port >= 0)
        (void) _port_dispatch(npp->np_lio_port, 0, PORT_SOURCE_AIO,
            npp->np_lio_event, npp->np_lio_object, npp->np_lio_user);
}

/*
 * Asynchronous notification worker.
 */
void *
_aio_do_notify(void *arg)
{
    aio_worker_t *aiowp = (aio_worker_t *)arg;
    aio_req_t *reqp;

    /*
     * This isn't really necessary.  All signals are blocked.
     */
    if (pthread_setspecific(_aio_key, aiowp) != 0)
        aio_panic("_aio_do_notify, pthread_setspecific()");

    /*
     * Notifications are never cancelled.
     * All signals remain blocked, forever.
     */
    for (;;) {
        while ((reqp = _aio_req_get(aiowp)) == NULL) {
            if (_aio_idle(aiowp) != 0)
                aio_panic("_aio_do_notify: _aio_idle() failed");
        }
        send_notification(&reqp->req_notify);
        _aio_req_free(reqp);
    }

    /* NOTREACHED */
    return (NULL);
}

/*
 * Do the completion semantics for a request that was either canceled
 * by _aio_cancel_req() or was completed by _aio_do_request().
 */
static void
_aiodone(aio_req_t *reqp, ssize_t retval, int error)
{
    aio_result_t *resultp = reqp->req_resultp;
    int notify = 0;
    aio_lio_t *head;
    int sigev_none;
    int sigev_signal;
    int sigev_thread;
    int sigev_port;
    notif_param_t np;

    /*
     * We call _aiodone() only for Posix I/O.
     */
    ASSERT(POSIX_AIO(reqp));

    sigev_none = 0;
    sigev_signal = 0;
    sigev_thread = 0;
    sigev_port = 0;
    np.np_signo = 0;
    np.np_port = -1;
    np.np_lio_signo = 0;
    np.np_lio_port = -1;

    switch (reqp->req_sigevent.sigev_notify) {
    case SIGEV_NONE:
        sigev_none = 1;
        break;
    case SIGEV_SIGNAL:
        sigev_signal = 1;
        break;
    case SIGEV_THREAD:
        sigev_thread = 1;
        break;
    case SIGEV_PORT:
        sigev_port = 1;
        break;
    default:
        aio_panic("_aiodone: improper sigev_notify");
        break;
    }

    /*
     * Figure out the notification parameters while holding __aio_mutex.
     * Actually perform the notifications after dropping __aio_mutex.
     * This allows us to sleep for a long time (if the notifications
     * incur delays) without impeding other async I/O operations.
     */

    sig_mutex_lock(&__aio_mutex);

    if (sigev_signal) {
        if ((np.np_signo = reqp->req_sigevent.sigev_signo) != 0)
            notify = 1;
        np.np_user = reqp->req_sigevent.sigev_value.sival_ptr;
    } else if (sigev_thread | sigev_port) {
        if ((np.np_port = reqp->req_sigevent.sigev_signo) >= 0)
            notify = 1;
        np.np_event = reqp->req_op;
        if (np.np_event == AIOFSYNC && reqp->req_largefile)
            np.np_event = AIOFSYNC64;
        np.np_object = (uintptr_t)reqp->req_aiocbp;
        np.np_user = reqp->req_sigevent.sigev_value.sival_ptr;
    }

    if (resultp->aio_errno == EINPROGRESS)
        _aio_set_result(reqp, retval, error);

    _aio_outstand_cnt--;

    head = reqp->req_head;
    reqp->req_head = NULL;

    if (sigev_none) {
        _aio_enq_doneq(reqp);
        reqp = NULL;
    } else {
        (void) _aio_hash_del(resultp);
        _aio_req_mark_done(reqp);
    }

    _aio_waitn_wakeup();

    /*
     * __aio_waitn() sets AIO_WAIT_INPROGRESS and
     * __aio_suspend() increments "_aio_kernel_suspend"
     * when they are waiting in the kernel for completed I/Os.
     *
     * _kaio(AIONOTIFY) awakes the corresponding function
     * in the kernel; then the corresponding __aio_waitn() or
     * __aio_suspend() function could reap the recently
     * completed I/Os (_aiodone()).
     */
    if ((_aio_flags & AIO_WAIT_INPROGRESS) || _aio_kernel_suspend > 0)
        (void) _kaio(AIONOTIFY);

    sig_mutex_unlock(&__aio_mutex);

    if (head != NULL) {
        /*
         * If all the lio requests have completed,
         * prepare to notify the waiting thread.
         */
        sig_mutex_lock(&head->lio_mutex);
        ASSERT(head->lio_refcnt == head->lio_nent);
        if (head->lio_refcnt == 1) {
            int waiting = 0;
            if (head->lio_mode == LIO_WAIT) {
                if ((waiting = head->lio_waiting) != 0)
                    (void) cond_signal(&head->lio_cond_cv);
            } else if (head->lio_port < 0) { /* none or signal */
                if ((np.np_lio_signo = head->lio_signo) != 0)
                    notify = 1;
                np.np_lio_user = head->lio_sigval.sival_ptr;
            } else {            /* thread or port */
                notify = 1;
                np.np_lio_port = head->lio_port;
                np.np_lio_event = head->lio_event;
                np.np_lio_object =
                    (uintptr_t)head->lio_sigevent;
                np.np_lio_user = head->lio_sigval.sival_ptr;
            }
            head->lio_nent = head->lio_refcnt = 0;
            sig_mutex_unlock(&head->lio_mutex);
            if (waiting == 0)
                _aio_lio_free(head);
        } else {
            head->lio_nent--;
            head->lio_refcnt--;
            sig_mutex_unlock(&head->lio_mutex);
        }
    }

    /*
     * The request is completed; now perform the notifications.
     */
    if (notify) {
        if (reqp != NULL) {
            /*
             * We usually put the request on the notification
             * queue because we don't want to block and delay
             * other operations behind us in the work queue.
             * Also we must never block on a cancel notification
             * because we are being called from an application
             * thread in this case and that could lead to deadlock
             * if no other thread is receiving notificatins.
             */
            reqp->req_notify = np;
            reqp->req_op = AIONOTIFY;
            _aio_req_add(reqp, &__workers_no, AIONOTIFY);
            reqp = NULL;
        } else {
            /*
             * We already put the request on the done queue,
             * so we can't queue it to the notification queue.
             * Just do the notification directly.
             */
            send_notification(&np);
        }
    }

    if (reqp != NULL)
        _aio_req_free(reqp);
}

/*
 * Delete fsync requests from list head until there is
 * only one left.  Return 0 when there is only one,
 * otherwise return a non-zero value.
 */
static int
_aio_fsync_del(aio_worker_t *aiowp, aio_req_t *reqp)
{
    aio_lio_t *head = reqp->req_head;
    int rval = 0;

    ASSERT(reqp == aiowp->work_req);
    sig_mutex_lock(&aiowp->work_qlock1);
    sig_mutex_lock(&head->lio_mutex);
    if (head->lio_refcnt > 1) {
        head->lio_refcnt--;
        head->lio_nent--;
        aiowp->work_req = NULL;
        sig_mutex_unlock(&head->lio_mutex);
        sig_mutex_unlock(&aiowp->work_qlock1);
        sig_mutex_lock(&__aio_mutex);
        _aio_outstand_cnt--;
        _aio_waitn_wakeup();
        sig_mutex_unlock(&__aio_mutex);
        _aio_req_free(reqp);
        return (1);
    }
    ASSERT(head->lio_nent == 1 && head->lio_refcnt == 1);
    reqp->req_head = NULL;
    if (head->lio_canned)
        reqp->req_state = AIO_REQ_CANCELED;
    if (head->lio_mode == LIO_DESTROY) {
        aiowp->work_req = NULL;
        rval = 1;
    }
    sig_mutex_unlock(&head->lio_mutex);
    sig_mutex_unlock(&aiowp->work_qlock1);
    head->lio_refcnt--;
    head->lio_nent--;
    _aio_lio_free(head);
    if (rval != 0)
        _aio_req_free(reqp);
    return (rval);
}

/*
 * A worker is set idle when its work queue is empty.
 * The worker checks again that it has no more work
 * and then goes to sleep waiting for more work.
 */
int
_aio_idle(aio_worker_t *aiowp)
{
    int error = 0;

    sig_mutex_lock(&aiowp->work_qlock1);
    if (aiowp->work_count1 == 0) {
        ASSERT(aiowp->work_minload1 == 0);
        aiowp->work_idleflg = 1;
        /*
         * A cancellation handler is not needed here.
         * aio worker threads are never cancelled via pthread_cancel().
         */
        error = sig_cond_wait(&aiowp->work_idle_cv,
            &aiowp->work_qlock1);
        /*
         * The idle flag is normally cleared before worker is awakened
         * by aio_req_add().  On error (EINTR), we clear it ourself.
         */
        if (error)
            aiowp->work_idleflg = 0;
    }
    sig_mutex_unlock(&aiowp->work_qlock1);
    return (error);
}

/*
 * A worker's completed AIO requests are placed onto a global
 * done queue.  The application is only sent a SIGIO signal if
 * the process has a handler enabled and it is not waiting via
 * aiowait().
 */
static void
_aio_work_done(aio_worker_t *aiowp)
{
    aio_req_t *reqp;

    sig_mutex_lock(&aiowp->work_qlock1);
    reqp = aiowp->work_prev1;
    reqp->req_next = NULL;
    aiowp->work_done1 = 0;
    aiowp->work_tail1 = aiowp->work_next1;
    if (aiowp->work_tail1 == NULL)
        aiowp->work_head1 = NULL;
    aiowp->work_prev1 = NULL;
    sig_mutex_unlock(&aiowp->work_qlock1);
    sig_mutex_lock(&__aio_mutex);
    _aio_donecnt++;
    _aio_outstand_cnt--;
    _aio_req_done_cnt--;
    ASSERT(_aio_donecnt > 0 &&
        _aio_outstand_cnt >= 0 &&
        _aio_req_done_cnt >= 0);
    ASSERT(reqp != NULL);

    if (_aio_done_tail == NULL) {
        _aio_done_head = _aio_done_tail = reqp;
    } else {
        _aio_done_head->req_next = reqp;
        _aio_done_head = reqp;
    }

    if (_aiowait_flag) {
        sig_mutex_unlock(&__aio_mutex);
        (void) _kaio(AIONOTIFY);
    } else {
        sig_mutex_unlock(&__aio_mutex);
        if (_sigio_enabled)
            (void) kill(__pid, SIGIO);
    }
}

/*
 * The done queue consists of AIO requests that are in either the
 * AIO_REQ_DONE or AIO_REQ_CANCELED state.  Requests that were cancelled
 * are discarded.  If the done queue is empty then NULL is returned.
 * Otherwise the address of a done aio_result_t is returned.
 */
aio_result_t *
_aio_req_done(void)
{
    aio_req_t *reqp;
    aio_result_t *resultp;

    ASSERT(MUTEX_HELD(&__aio_mutex));

    if ((reqp = _aio_done_tail) != NULL) {
        if ((_aio_done_tail = reqp->req_next) == NULL)
            _aio_done_head = NULL;
        ASSERT(_aio_donecnt > 0);
        _aio_donecnt--;
        (void) _aio_hash_del(reqp->req_resultp);
        resultp = reqp->req_resultp;
        ASSERT(reqp->req_state == AIO_REQ_DONE);
        _aio_req_free(reqp);
        return (resultp);
    }
    /* is queue empty? */
    if (reqp == NULL && _aio_outstand_cnt == 0) {
        return ((aio_result_t *)-1);
    }
    return (NULL);
}

/*
 * Set the return and errno values for the application's use.
 *
 * For the Posix interfaces, we must set the return value first followed
 * by the errno value because the Posix interfaces allow for a change
 * in the errno value from EINPROGRESS to something else to signal
 * the completion of the asynchronous request.
 *
 * The opposite is true for the Solaris interfaces.  These allow for
 * a change in the return value from AIO_INPROGRESS to something else
 * to signal the completion of the asynchronous request.
 */
void
_aio_set_result(aio_req_t *reqp, ssize_t retval, int error)
{
    aio_result_t *resultp = reqp->req_resultp;

    if (POSIX_AIO(reqp)) {
        resultp->aio_return = retval;
        membar_producer();
        resultp->aio_errno = error;
    } else {
        resultp->aio_errno = error;
        membar_producer();
        resultp->aio_return = retval;
    }
}

/*
 * Add an AIO request onto the next work queue.
 * A circular list of workers is used to choose the next worker.
 */
void
_aio_req_add(aio_req_t *reqp, aio_worker_t **nextworker, int mode)
{
    ulwp_t *self = curthread;
    aio_worker_t *aiowp;
    aio_worker_t *first;
    int load_bal_flg = 1;
    int found;

    ASSERT(reqp->req_state != AIO_REQ_DONEQ);
    reqp->req_next = NULL;
    /*
     * Try to acquire the next worker's work queue.  If it is locked,
     * then search the list of workers until a queue is found unlocked,
     * or until the list is completely traversed at which point another
     * worker will be created.
     */
    sigoff(self);       /* defer SIGIO */
    sig_mutex_lock(&__aio_mutex);
    first = aiowp = *nextworker;
    if (mode != AIONOTIFY)
        _aio_outstand_cnt++;
    sig_mutex_unlock(&__aio_mutex);

    switch (mode) {
    case AIOREAD:
    case AIOWRITE:
    case AIOAREAD:
    case AIOAWRITE:
#if !defined(_LP64)
    case AIOAREAD64:
    case AIOAWRITE64:
#endif
        /* try to find an idle worker */
        found = 0;
        do {
            if (sig_mutex_trylock(&aiowp->work_qlock1) == 0) {
                if (aiowp->work_idleflg) {
                    found = 1;
                    break;
                }
                sig_mutex_unlock(&aiowp->work_qlock1);
            }
        } while ((aiowp = aiowp->work_forw) != first);

        if (found) {
            aiowp->work_minload1++;
            break;
        }

        /* try to acquire some worker's queue lock */
        do {
            if (sig_mutex_trylock(&aiowp->work_qlock1) == 0) {
                found = 1;
                break;
            }
        } while ((aiowp = aiowp->work_forw) != first);

        /*
         * Create more workers when the workers appear overloaded.
         * Either all the workers are busy draining their queues
         * or no worker's queue lock could be acquired.
         */
        if (!found) {
            if (_aio_worker_cnt < _max_workers) {
                if (_aio_create_worker(reqp, mode))
                    aio_panic("_aio_req_add: add worker");
                sigon(self);    /* reenable SIGIO */
                return;
            }

            /*
             * No worker available and we have created
             * _max_workers, keep going through the
             * list slowly until we get a lock
             */
            while (sig_mutex_trylock(&aiowp->work_qlock1) != 0) {
                /*
                 * give someone else a chance
                 */
                _aio_delay(1);
                aiowp = aiowp->work_forw;
            }
        }

        ASSERT(MUTEX_HELD(&aiowp->work_qlock1));
        if (_aio_worker_cnt < _max_workers &&
            aiowp->work_minload1 >= _minworkload) {
            sig_mutex_unlock(&aiowp->work_qlock1);
            sig_mutex_lock(&__aio_mutex);
            *nextworker = aiowp->work_forw;
            sig_mutex_unlock(&__aio_mutex);
            if (_aio_create_worker(reqp, mode))
                aio_panic("aio_req_add: add worker");
            sigon(self);    /* reenable SIGIO */
            return;
        }
        aiowp->work_minload1++;
        break;
    case AIOFSYNC:
    case AIONOTIFY:
        load_bal_flg = 0;
        sig_mutex_lock(&aiowp->work_qlock1);
        break;
    default:
        aio_panic("_aio_req_add: invalid mode");
        break;
    }
    /*
     * Put request onto worker's work queue.
     */
    if (aiowp->work_tail1 == NULL) {
        ASSERT(aiowp->work_count1 == 0);
        aiowp->work_tail1 = reqp;
        aiowp->work_next1 = reqp;
    } else {
        aiowp->work_head1->req_next = reqp;
        if (aiowp->work_next1 == NULL)
            aiowp->work_next1 = reqp;
    }
    reqp->req_state = AIO_REQ_QUEUED;
    reqp->req_worker = aiowp;
    aiowp->work_head1 = reqp;
    /*
     * Awaken worker if it is not currently active.
     */
    if (aiowp->work_count1++ == 0 && aiowp->work_idleflg) {
        aiowp->work_idleflg = 0;
        (void) cond_signal(&aiowp->work_idle_cv);
    }
    sig_mutex_unlock(&aiowp->work_qlock1);

    if (load_bal_flg) {
        sig_mutex_lock(&__aio_mutex);
        *nextworker = aiowp->work_forw;
        sig_mutex_unlock(&__aio_mutex);
    }
    sigon(self);    /* reenable SIGIO */
}

/*
 * Get an AIO request for a specified worker.
 * If the work queue is empty, return NULL.
 */
aio_req_t *
_aio_req_get(aio_worker_t *aiowp)
{
    aio_req_t *reqp;

    sig_mutex_lock(&aiowp->work_qlock1);
    if ((reqp = aiowp->work_next1) != NULL) {
        /*
         * Remove a POSIX request from the queue; the
         * request queue is a singularly linked list
         * with a previous pointer.  The request is
         * removed by updating the previous pointer.
         *
         * Non-posix requests are left on the queue
         * to eventually be placed on the done queue.
         */

        if (POSIX_AIO(reqp)) {
            if (aiowp->work_prev1 == NULL) {
                aiowp->work_tail1 = reqp->req_next;
                if (aiowp->work_tail1 == NULL)
                    aiowp->work_head1 = NULL;
            } else {
                aiowp->work_prev1->req_next = reqp->req_next;
                if (aiowp->work_head1 == reqp)
                    aiowp->work_head1 = reqp->req_next;
            }

        } else {
            aiowp->work_prev1 = reqp;
            ASSERT(aiowp->work_done1 >= 0);
            aiowp->work_done1++;
        }
        ASSERT(reqp != reqp->req_next);
        aiowp->work_next1 = reqp->req_next;
        ASSERT(aiowp->work_count1 >= 1);
        aiowp->work_count1--;
        switch (reqp->req_op) {
        case AIOREAD:
        case AIOWRITE:
        case AIOAREAD:
        case AIOAWRITE:
#if !defined(_LP64)
        case AIOAREAD64:
        case AIOAWRITE64:
#endif
            ASSERT(aiowp->work_minload1 > 0);
            aiowp->work_minload1--;
            break;
        }
        reqp->req_state = AIO_REQ_INPROGRESS;
    }
    aiowp->work_req = reqp;
    ASSERT(reqp != NULL || aiowp->work_count1 == 0);
    sig_mutex_unlock(&aiowp->work_qlock1);
    return (reqp);
}

static void
_aio_req_del(aio_worker_t *aiowp, aio_req_t *reqp, int ostate)
{
    aio_req_t **last;
    aio_req_t *lastrp;
    aio_req_t *next;

    ASSERT(aiowp != NULL);
    ASSERT(MUTEX_HELD(&aiowp->work_qlock1));
    if (POSIX_AIO(reqp)) {
        if (ostate != AIO_REQ_QUEUED)
            return;
    }
    last = &aiowp->work_tail1;
    lastrp = aiowp->work_tail1;
    ASSERT(ostate == AIO_REQ_QUEUED || ostate == AIO_REQ_INPROGRESS);
    while ((next = *last) != NULL) {
        if (next == reqp) {
            *last = next->req_next;
            if (aiowp->work_next1 == next)
                aiowp->work_next1 = next->req_next;

            if ((next->req_next != NULL) ||
                (aiowp->work_done1 == 0)) {
                if (aiowp->work_head1 == next)
                    aiowp->work_head1 = next->req_next;
                if (aiowp->work_prev1 == next)
                    aiowp->work_prev1 = next->req_next;
            } else {
                if (aiowp->work_head1 == next)
                    aiowp->work_head1 = lastrp;
                if (aiowp->work_prev1 == next)
                    aiowp->work_prev1 = lastrp;
            }

            if (ostate == AIO_REQ_QUEUED) {
                ASSERT(aiowp->work_count1 >= 1);
                aiowp->work_count1--;
                ASSERT(aiowp->work_minload1 >= 1);
                aiowp->work_minload1--;
            } else {
                ASSERT(ostate == AIO_REQ_INPROGRESS &&
                    !POSIX_AIO(reqp));
                aiowp->work_done1--;
            }
            return;
        }
        last = &next->req_next;
        lastrp = next;
    }
    /* NOTREACHED */
}

static void
_aio_enq_doneq(aio_req_t *reqp)
{
    if (_aio_doneq == NULL) {
        _aio_doneq = reqp;
        reqp->req_next = reqp->req_prev = reqp;
    } else {
        reqp->req_next = _aio_doneq;
        reqp->req_prev = _aio_doneq->req_prev;
        _aio_doneq->req_prev->req_next = reqp;
        _aio_doneq->req_prev = reqp;
    }
    reqp->req_state = AIO_REQ_DONEQ;
    _aio_doneq_cnt++;
}

/*
 * caller owns the _aio_mutex
 */
aio_req_t *
_aio_req_remove(aio_req_t *reqp)
{
    if (reqp && reqp->req_state != AIO_REQ_DONEQ)
        return (NULL);

    if (reqp) {
        /* request in done queue */
        if (_aio_doneq == reqp)
            _aio_doneq = reqp->req_next;
        if (_aio_doneq == reqp) {
            /* only one request on queue */
            _aio_doneq = NULL;
        } else {
            aio_req_t *tmp = reqp->req_next;
            reqp->req_prev->req_next = tmp;
            tmp->req_prev = reqp->req_prev;
        }
    } else if ((reqp = _aio_doneq) != NULL) {
        if (reqp == reqp->req_next) {
            /* only one request on queue */
            _aio_doneq = NULL;
        } else {
            reqp->req_prev->req_next = _aio_doneq = reqp->req_next;
            _aio_doneq->req_prev = reqp->req_prev;
        }
    }
    if (reqp) {
        _aio_doneq_cnt--;
        reqp->req_next = reqp->req_prev = reqp;
        reqp->req_state = AIO_REQ_DONE;
    }
    return (reqp);
}

/*
 * An AIO request is identified by an aio_result_t pointer.  The library
 * maps this aio_result_t pointer to its internal representation using a
 * hash table.  This function adds an aio_result_t pointer to the hash table.
 */
static int
_aio_hash_insert(aio_result_t *resultp, aio_req_t *reqp)
{
    aio_hash_t *hashp;
    aio_req_t **prev;
    aio_req_t *next;

    hashp = _aio_hash + AIOHASH(resultp);
    lmutex_lock(&hashp->hash_lock);
    prev = &hashp->hash_ptr;
    while ((next = *prev) != NULL) {
        if (resultp == next->req_resultp) {
            lmutex_unlock(&hashp->hash_lock);
            return (-1);
        }
        prev = &next->req_link;
    }
    *prev = reqp;
    ASSERT(reqp->req_link == NULL);
    lmutex_unlock(&hashp->hash_lock);
    return (0);
}

/*
 * Remove an entry from the hash table.
 */
aio_req_t *
_aio_hash_del(aio_result_t *resultp)
{
    aio_hash_t *hashp;
    aio_req_t **prev;
    aio_req_t *next = NULL;

    if (_aio_hash != NULL) {
        hashp = _aio_hash + AIOHASH(resultp);
        lmutex_lock(&hashp->hash_lock);
        prev = &hashp->hash_ptr;
        while ((next = *prev) != NULL) {
            if (resultp == next->req_resultp) {
                *prev = next->req_link;
                next->req_link = NULL;
                break;
            }
            prev = &next->req_link;
        }
        lmutex_unlock(&hashp->hash_lock);
    }
    return (next);
}

/*
 *  find an entry in the hash table
 */
aio_req_t *
_aio_hash_find(aio_result_t *resultp)
{
    aio_hash_t *hashp;
    aio_req_t **prev;
    aio_req_t *next = NULL;

    if (_aio_hash != NULL) {
        hashp = _aio_hash + AIOHASH(resultp);
        lmutex_lock(&hashp->hash_lock);
        prev = &hashp->hash_ptr;
        while ((next = *prev) != NULL) {
            if (resultp == next->req_resultp)
                break;
            prev = &next->req_link;
        }
        lmutex_unlock(&hashp->hash_lock);
    }
    return (next);
}

/*
 * AIO interface for POSIX
 */
int
_aio_rw(aiocb_t *aiocbp, aio_lio_t *lio_head, aio_worker_t **nextworker,
    int mode, int flg)
{
    aio_req_t *reqp;
    aio_args_t *ap;
    int kerr;

    if (aiocbp == NULL) {
        errno = EINVAL;
        return (-1);
    }

    /* initialize kaio */
    if (!_kaio_ok)
        _kaio_init();

    aiocbp->aio_state = NOCHECK;

    /*
     * If we have been called because a list I/O
     * kaio() failed, we dont want to repeat the
     * system call
     */

    if (flg & AIO_KAIO) {
        /*
         * Try kernel aio first.
         * If errno is ENOTSUP/EBADFD,
         * fall back to the thread implementation.
         */
        if (_kaio_ok > 0 && KAIO_SUPPORTED(aiocbp->aio_fildes)) {
            aiocbp->aio_resultp.aio_errno = EINPROGRESS;
            aiocbp->aio_state = CHECK;
            kerr = (int)_kaio(mode, aiocbp);
            if (kerr == 0)
                return (0);
            if (errno != ENOTSUP && errno != EBADFD) {
                aiocbp->aio_resultp.aio_errno = errno;
                aiocbp->aio_resultp.aio_return = -1;
                aiocbp->aio_state = NOCHECK;
                return (-1);
            }
            if (errno == EBADFD)
                SET_KAIO_NOT_SUPPORTED(aiocbp->aio_fildes);
        }
    }

    aiocbp->aio_resultp.aio_errno = EINPROGRESS;
    aiocbp->aio_state = USERAIO;

    if (!__uaio_ok && __uaio_init() == -1)
        return (-1);

    if ((reqp = _aio_req_alloc()) == NULL) {
        errno = EAGAIN;
        return (-1);
    }

    /*
     * If an LIO request, add the list head to the aio request
     */
    reqp->req_head = lio_head;
    reqp->req_type = AIO_POSIX_REQ;
    reqp->req_op = mode;
    reqp->req_largefile = 0;

    if (aiocbp->aio_sigevent.sigev_notify == SIGEV_NONE) {
        reqp->req_sigevent.sigev_notify = SIGEV_NONE;
    } else if (aiocbp->aio_sigevent.sigev_notify == SIGEV_SIGNAL) {
        reqp->req_sigevent.sigev_notify = SIGEV_SIGNAL;
        reqp->req_sigevent.sigev_signo =
            aiocbp->aio_sigevent.sigev_signo;
        reqp->req_sigevent.sigev_value.sival_ptr =
            aiocbp->aio_sigevent.sigev_value.sival_ptr;
    } else if (aiocbp->aio_sigevent.sigev_notify == SIGEV_PORT) {
        port_notify_t *pn = aiocbp->aio_sigevent.sigev_value.sival_ptr;
        reqp->req_sigevent.sigev_notify = SIGEV_PORT;
        /*
         * Reuse the sigevent structure to contain the port number
         * and the user value.  Same for SIGEV_THREAD, below.
         */
        reqp->req_sigevent.sigev_signo =
            pn->portnfy_port;
        reqp->req_sigevent.sigev_value.sival_ptr =
            pn->portnfy_user;
    } else if (aiocbp->aio_sigevent.sigev_notify == SIGEV_THREAD) {
        reqp->req_sigevent.sigev_notify = SIGEV_THREAD;
        /*
         * The sigevent structure contains the port number
         * and the user value.  Same for SIGEV_PORT, above.
         */
        reqp->req_sigevent.sigev_signo =
            aiocbp->aio_sigevent.sigev_signo;
        reqp->req_sigevent.sigev_value.sival_ptr =
            aiocbp->aio_sigevent.sigev_value.sival_ptr;
    }

    reqp->req_resultp = &aiocbp->aio_resultp;
    reqp->req_aiocbp = aiocbp;
    ap = &reqp->req_args;
    ap->fd = aiocbp->aio_fildes;
    ap->buf = (caddr_t)aiocbp->aio_buf;
    ap->bufsz = aiocbp->aio_nbytes;
    ap->offset = aiocbp->aio_offset;

    if ((flg & AIO_NO_DUPS) &&
        _aio_hash_insert(&aiocbp->aio_resultp, reqp) != 0) {
        aio_panic("_aio_rw(): request already in hash table");
        _aio_req_free(reqp);
        errno = EINVAL;
        return (-1);
    }
    _aio_req_add(reqp, nextworker, mode);
    return (0);
}

#if !defined(_LP64)
/*
 * 64-bit AIO interface for POSIX
 */
int
_aio_rw64(aiocb64_t *aiocbp, aio_lio_t *lio_head, aio_worker_t **nextworker,
    int mode, int flg)
{
    aio_req_t *reqp;
    aio_args_t *ap;
    int kerr;

    if (aiocbp == NULL) {
        errno = EINVAL;
        return (-1);
    }

    /* initialize kaio */
    if (!_kaio_ok)
        _kaio_init();

    aiocbp->aio_state = NOCHECK;

    /*
     * If we have been called because a list I/O
     * kaio() failed, we dont want to repeat the
     * system call
     */

    if (flg & AIO_KAIO) {
        /*
         * Try kernel aio first.
         * If errno is ENOTSUP/EBADFD,
         * fall back to the thread implementation.
         */
        if (_kaio_ok > 0 && KAIO_SUPPORTED(aiocbp->aio_fildes)) {
            aiocbp->aio_resultp.aio_errno = EINPROGRESS;
            aiocbp->aio_state = CHECK;
            kerr = (int)_kaio(mode, aiocbp);
            if (kerr == 0)
                return (0);
            if (errno != ENOTSUP && errno != EBADFD) {
                aiocbp->aio_resultp.aio_errno = errno;
                aiocbp->aio_resultp.aio_return = -1;
                aiocbp->aio_state = NOCHECK;
                return (-1);
            }
            if (errno == EBADFD)
                SET_KAIO_NOT_SUPPORTED(aiocbp->aio_fildes);
        }
    }

    aiocbp->aio_resultp.aio_errno = EINPROGRESS;
    aiocbp->aio_state = USERAIO;

    if (!__uaio_ok && __uaio_init() == -1)
        return (-1);

    if ((reqp = _aio_req_alloc()) == NULL) {
        errno = EAGAIN;
        return (-1);
    }

    /*
     * If an LIO request, add the list head to the aio request
     */
    reqp->req_head = lio_head;
    reqp->req_type = AIO_POSIX_REQ;
    reqp->req_op = mode;
    reqp->req_largefile = 1;

    if (aiocbp->aio_sigevent.sigev_notify == SIGEV_NONE) {
        reqp->req_sigevent.sigev_notify = SIGEV_NONE;
    } else if (aiocbp->aio_sigevent.sigev_notify == SIGEV_SIGNAL) {
        reqp->req_sigevent.sigev_notify = SIGEV_SIGNAL;
        reqp->req_sigevent.sigev_signo =
            aiocbp->aio_sigevent.sigev_signo;
        reqp->req_sigevent.sigev_value.sival_ptr =
            aiocbp->aio_sigevent.sigev_value.sival_ptr;
    } else if (aiocbp->aio_sigevent.sigev_notify == SIGEV_PORT) {
        port_notify_t *pn = aiocbp->aio_sigevent.sigev_value.sival_ptr;
        reqp->req_sigevent.sigev_notify = SIGEV_PORT;
        reqp->req_sigevent.sigev_signo =
            pn->portnfy_port;
        reqp->req_sigevent.sigev_value.sival_ptr =
            pn->portnfy_user;
    } else if (aiocbp->aio_sigevent.sigev_notify == SIGEV_THREAD) {
        reqp->req_sigevent.sigev_notify = SIGEV_THREAD;
        reqp->req_sigevent.sigev_signo =
            aiocbp->aio_sigevent.sigev_signo;
        reqp->req_sigevent.sigev_value.sival_ptr =
            aiocbp->aio_sigevent.sigev_value.sival_ptr;
    }

    reqp->req_resultp = &aiocbp->aio_resultp;
    reqp->req_aiocbp = aiocbp;
    ap = &reqp->req_args;
    ap->fd = aiocbp->aio_fildes;
    ap->buf = (caddr_t)aiocbp->aio_buf;
    ap->bufsz = aiocbp->aio_nbytes;
    ap->offset = aiocbp->aio_offset;

    if ((flg & AIO_NO_DUPS) &&
        _aio_hash_insert(&aiocbp->aio_resultp, reqp) != 0) {
        aio_panic("_aio_rw64(): request already in hash table");
        _aio_req_free(reqp);
        errno = EINVAL;
        return (-1);
    }
    _aio_req_add(reqp, nextworker, mode);
    return (0);
}
#endif  /* !defined(_LP64) */