io/oplmsu/oplmsu_cmn_func.c

/*
 * 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
 */
/*
 * All Rights Reserved, Copyright (c) FUJITSU LIMITED 2006
 */

#include <sys/errno.h>
#include <sys/modctl.h>
#include <sys/stat.h>
#include <sys/kmem.h>
#include <sys/ksynch.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/termio.h>
#include <sys/ddi.h>
#include <sys/file.h>
#include <sys/disp.h>
#include <sys/sunddi.h>
#include <sys/sunldi.h>
#include <sys/sunndi.h>
#include <sys/strsun.h>
#include <sys/oplmsu/oplmsu.h>
#include <sys/oplmsu/oplmsu_proto.h>

/*
 * Link upper_path_table structure
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : A
 */
void
oplmsu_link_upath(upath_t *add_upath)
{

    ASSERT(add_upath != NULL);
    ASSERT(RW_WRITE_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

    if (oplmsu_uinst->first_upath == NULL) {
        oplmsu_uinst->first_upath = add_upath;
        add_upath->u_prev = NULL;
    } else {
        upath_t *last_upath;

        last_upath = oplmsu_uinst->last_upath;
        last_upath->u_next = add_upath;
        add_upath->u_prev = last_upath;
    }

    oplmsu_uinst->last_upath = add_upath;
    add_upath->u_next = NULL;
}

/*
 * Unlink upper_path_table structure
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_WRITER]
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_unlink_upath(upath_t *del_upath)
{
    upath_t **first, **last;

    ASSERT(RW_WRITE_HELD(&oplmsu_uinst->lock));

    first = &oplmsu_uinst->first_upath;
    last = &oplmsu_uinst->last_upath;

    if ((*first != del_upath) && (*last != del_upath)) {
        del_upath->u_prev->u_next = del_upath->u_next;
        del_upath->u_next->u_prev = del_upath->u_prev;
    } else {
        if (*first == del_upath) {
            *first = (*first)->u_next;
            if (*first) {
                (*first)->u_prev = NULL;
            }
        }

        if (*last == del_upath) {
            *last = (*last)->u_prev;
            if (*last) {
                (*last)->u_next = NULL;
            }
        }
    }

    del_upath->u_next = NULL;
    del_upath->u_prev = NULL;
}

/*
 * Link lower_path_table structure
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : M
 *  -. uinst_t->c_lock : A
 */
void
oplmsu_link_lpath(lpath_t *add_lpath)
{

    ASSERT(add_lpath != NULL);
    ASSERT(RW_WRITE_HELD(&oplmsu_uinst->lock));

    if (oplmsu_uinst->first_lpath == NULL) {
        oplmsu_uinst->first_lpath = add_lpath;
        add_lpath->l_prev = NULL;
    } else {
        lpath_t *last_lpath;

        last_lpath = oplmsu_uinst->last_lpath;
        last_lpath->l_next = add_lpath;
        add_lpath->l_prev = last_lpath;
    }

    oplmsu_uinst->last_lpath = add_lpath;
    add_lpath->l_next = NULL;
}

/*
 * Unlink lower_path_table structure
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_WRITER]
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_unlink_lpath(lpath_t *del_lpath)
{
    lpath_t **first, **last;

    ASSERT(RW_WRITE_HELD(&oplmsu_uinst->lock));

    first = &oplmsu_uinst->first_lpath;
    last = &oplmsu_uinst->last_lpath;

    if ((*first != del_lpath) && (*last != del_lpath)) {
        del_lpath->l_prev->l_next = del_lpath->l_next;
        del_lpath->l_next->l_prev = del_lpath->l_prev;
    } else {
        if (*first == del_lpath) {
            *first = (*first)->l_next;
            if (*first) {
                (*first)->l_prev = NULL;
            }
        }

        if (*last == del_lpath) {
            *last = (*last)->l_prev;
            if (*last) {
                (*last)->l_next = NULL;
            }
        }
    }

    del_lpath->l_next = NULL;
    del_lpath->l_prev = NULL;
}

/*
 * Link msgb structure of high priority
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : A [It depends on caller]
 *  -. uinst_t->c_lock : A [It depends on caller]
 */
void
oplmsu_link_high_primsg(mblk_t **first, mblk_t **last, mblk_t *add_msg)
{

    ASSERT(add_msg != NULL);
    ASSERT(RW_READ_HELD(&oplmsu_uinst->lock));

    if (*first == NULL) {
        *first = add_msg;
        add_msg->b_prev = NULL;
    } else {
        (*last)->b_next = add_msg;
        add_msg->b_prev = *last;
    }

    *last = add_msg;
    add_msg->b_next = NULL;
}

/*
 * Check whether lower path is usable by lower path info table address
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : M
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_check_lpath_usable(void)
{
    lpath_t *lpath;
    int rval = SUCCESS;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->l_lock));

    lpath = oplmsu_uinst->first_lpath;
    while (lpath) {
        if ((lpath->hndl_uqueue != NULL) || (lpath->hndl_mp != NULL)) {
            rval = BUSY;
            break;
        }
        lpath = lpath->l_next;
    }
    return (rval);
}

/*
 * Search upath_t by path number
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : P
 */
upath_t *
oplmsu_search_upath_info(int path_no)
{
    upath_t *upath;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

    upath = oplmsu_uinst->first_upath;
    while (upath) {
        if (upath->path_no == path_no) {
            break;
        }
        upath = upath->u_next;
    }
    return (upath);
}

/*
 * Send M_IOCACK(or M_IOCNAK) message to stream
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : P
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_iocack(queue_t *q, mblk_t *mp, int errno)
{
    struct iocblk   *iocp = NULL;

    ASSERT(mp != NULL);

    iocp = (struct iocblk *)mp->b_rptr;
    iocp->ioc_error = errno;

    if (errno) {    /* Error */
        mp->b_datap->db_type = M_IOCNAK;
        iocp->ioc_rval = FAILURE;

        OPLMSU_TRACE(q, mp, MSU_TRC_UO);
        qreply(q, mp);
    } else {    /* Good */
        mp->b_datap->db_type = M_IOCACK;
        iocp->ioc_rval = SUCCESS;

        OPLMSU_TRACE(q, mp, MSU_TRC_UO);
        qreply(q, mp);
    }
}

/*
 * Delete all upath_t
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : A
 */
void
oplmsu_delete_upath_info(void)
{
    upath_t *upath, *next_upath;

    ASSERT(RW_WRITE_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

    upath = oplmsu_uinst->first_upath;
    oplmsu_uinst->first_upath = NULL;
    oplmsu_uinst->last_upath = NULL;

    while (upath) {
        next_upath = upath->u_next;
        kmem_free(upath, sizeof (upath_t));
        upath = next_upath;
    }
}

/*
 * Set queue and ioctl to lpath_t
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : M
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_set_ioctl_path(lpath_t *lpath, queue_t *hndl_queue, mblk_t *mp)
{
    int rval = SUCCESS;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->l_lock));

    if ((lpath->hndl_uqueue == NULL) && (lpath->hndl_mp == NULL) &&
        (lpath->sw_flag == 0)) {
        if ((lpath->status == MSU_EXT_NOTUSED) ||
            (lpath->status == MSU_EXT_ACTIVE_CANDIDATE) ||
            (lpath->status == MSU_SETID_NU)) {
            if (hndl_queue == NULL) {
                lpath->hndl_uqueue = hndl_queue;
            } else {
                lpath->hndl_uqueue = WR(hndl_queue);
            }
            lpath->hndl_mp = mp;
        } else {
            rval = BUSY;
        }
    } else {
        rval = BUSY;
    }
    return (rval);
}

/*
 * Clear queue and ioctl to lpath_t
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : M
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_clear_ioctl_path(lpath_t *lpath)
{

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->l_lock));

    lpath->hndl_uqueue = NULL;
    lpath->hndl_mp = NULL;
}

/*
 * Get instanse status from status of upath_t
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_get_inst_status(void)
{
    upath_t *upath;
    int sts, pre_sts = INST_STAT_UNCONFIGURED;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

    upath = oplmsu_uinst->first_upath;
    while (upath) {
        if (((upath->status == MSU_PSTAT_ACTIVE) &&
            (upath->traditional_status == MSU_ACTIVE)) ||
            ((upath->status == MSU_PSTAT_STANDBY) &&
            (upath->traditional_status == MSU_STANDBY))) {
            sts = INST_STAT_ONLINE;
        } else if (((upath->status == MSU_PSTAT_STOP) &&
            (upath->traditional_status == MSU_STOP)) ||
            ((upath->status == MSU_PSTAT_FAIL) &&
            (upath->traditional_status == MSU_FAIL))) {
            sts = INST_STAT_OFFLINE;
        } else if (((upath->status == MSU_PSTAT_DISCON) &&
            (upath->traditional_status == MSU_DISCON)) ||
            ((upath->status == MSU_PSTAT_EMPTY) &&
            (upath->traditional_status == MSU_EMPTY))) {
            sts = INST_STAT_UNCONFIGURED;
        } else {
            sts = INST_STAT_BUSY;
        }

        if (pre_sts > sts) {
            pre_sts = sts;
        }
        upath = upath->u_next;
    }
    return (pre_sts);
}

/*
 * Search path of "online:standby" status
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : P
 */
upath_t *
oplmsu_search_standby(void)
{
    upath_t *upath, *altn_upath = NULL;
    int max_pathnum = UNDEFINED;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

    upath = oplmsu_uinst->first_upath;
    while (upath) {
        if ((upath->status == MSU_PSTAT_STANDBY) &&
            (upath->traditional_status == MSU_STANDBY) &&
            (upath->lpath != NULL)) {
            if ((max_pathnum == UNDEFINED) ||
                (max_pathnum > upath->path_no)) {
                max_pathnum = upath->path_no;
                altn_upath = upath;
            }
        }
        upath = upath->u_next;
    }
    return (altn_upath);
}

/*
 * Search path of "offline:stop" status, and minimum path number
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_search_min_stop_path(void)
{
    upath_t *upath, *min_upath;
    lpath_t *lpath;
    int min_no = UNDEFINED;
    int active_flag = 0;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

    upath = oplmsu_uinst->first_upath;
    while (upath) {
        if ((upath->status == MSU_PSTAT_ACTIVE) &&
            (upath->traditional_status == MSU_ACTIVE)) {
            active_flag = 1;
            break;
        } else if ((upath->status == MSU_PSTAT_STOP) &&
            (upath->traditional_status == MSU_STOP)) {
            if (upath->lpath != NULL) {
                if ((min_no == UNDEFINED) ||
                    (upath->path_no < min_no)) {
                    lpath = upath->lpath;
                    mutex_enter(&oplmsu_uinst->l_lock);
                    if (lpath->status == MSU_EXT_NOTUSED) {
                        min_upath = upath;
                        min_no = upath->path_no;
                    }
                    mutex_exit(&oplmsu_uinst->l_lock);
                }
            }
        }
        upath = upath->u_next;
    }

    if (active_flag == 0) {
        lpath = min_upath->lpath;
        mutex_enter(&oplmsu_uinst->l_lock);
        lpath->src_upath = NULL;
        lpath->status = MSU_EXT_ACTIVE_CANDIDATE;
        mutex_exit(&oplmsu_uinst->l_lock);
    }
}

/*
 * Get the total number of serial paths
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : A
 */
int
oplmsu_get_pathnum(void)
{
    upath_t *upath;
    int total_num = 0;

    ASSERT(RW_WRITE_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

    if (oplmsu_uinst->first_upath != NULL) {
        upath = oplmsu_uinst->first_upath;
        while (upath) {
            total_num++;
            upath = upath->u_next;
        }
    }
    return (total_num);
}

/*
 * Put XOFF/ XON message on write queue
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : A
 */
int
oplmsu_cmn_put_xoffxon(queue_t *queue, int data)
{
    mblk_t  *mp;
    int rval = SUCCESS;

    /* Send M_START */
    if ((mp = allocb(0, BPRI_LO)) != NULL) {
        mp->b_datap->db_type = M_START;
        (void) putq(queue, mp);

        /* Send M_DATA(XOFF, XON) */
        if ((mp = allocb(sizeof (int), BPRI_LO)) != NULL) {
            *(uint_t *)mp->b_rptr = data;
            mp->b_wptr = mp->b_rptr + sizeof (int);
            (void) putq(queue, mp);
        } else {
            rval = FAILURE;
        }
    } else {
        rval = FAILURE;
    }
    return (rval);
}

/*
 * Put XOFF message on write queue for all standby paths
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : M
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_cmn_putxoff_standby(void)
{
    upath_t *upath;
    lpath_t *lpath;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->l_lock));

    upath = oplmsu_uinst->first_upath;
    while (upath) {
        lpath = upath->lpath;
        if ((upath->status != MSU_PSTAT_STANDBY) ||
            (lpath == NULL)) {
            upath = upath->u_next;
            continue;
        }

        (void) oplmsu_cmn_put_xoffxon(
            WR(lpath->lower_queue), MSU_XOFF_4);
        upath = upath->u_next;
    }
}

/*
 * Set M_FLUSH message
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : A [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : A
 */
void
oplmsu_cmn_set_mflush(mblk_t *mp)
{

    mp->b_datap->db_type = M_FLUSH;
    *mp->b_rptr = FLUSHW;
    mp->b_wptr = mp->b_rptr + sizeof (char);
}

/*
 * Set status informations of upath_t
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : M
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : A
 */
void
oplmsu_cmn_set_upath_sts(upath_t *upath, int sts, int prev_sts,
    ulong_t trad_sts)
{

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->u_lock));

    upath->status = sts;
    upath->prev_status = prev_sts;
    upath->traditional_status = trad_sts;
}

/*
 * Allocate a message block
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_cmn_allocmb(queue_t *q, mblk_t *mp, mblk_t **nmp, size_t size,
    int rw_flag)
{
    int rval = SUCCESS;

    ASSERT(RW_READ_HELD(&oplmsu_uinst->lock));

    if ((*nmp = (mblk_t *)allocb(size, BPRI_LO)) == NULL) {
        oplmsu_cmn_bufcall(q, mp, size, rw_flag);
        rval = FAILURE;
    } else {
        (*nmp)->b_wptr = (*nmp)->b_rptr + size;
    }
    return (rval);
}

/*
 * Copy a message
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_cmn_copymb(queue_t *q, mblk_t *mp, mblk_t **nmp, mblk_t *cmp,
    int rw_flag)
{
    int rval = SUCCESS;

    ASSERT(RW_READ_HELD(&oplmsu_uinst->lock));

    if ((*nmp = copymsg(cmp)) == NULL) {
        oplmsu_cmn_bufcall(q, mp, msgsize(cmp), rw_flag);
        rval = FAILURE;
    }
    return (rval);
}

/*
 * bufcall request
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_cmn_bufcall(queue_t *q, mblk_t *mp, size_t size, int rw_flag)
{

    ASSERT(RW_READ_HELD(&oplmsu_uinst->lock));

    if (rw_flag == MSU_WRITE_SIDE) {
        ctrl_t  *ctrl;

        (void) putbq(q, mp);

        mutex_enter(&oplmsu_uinst->c_lock);
        ctrl = (ctrl_t *)q->q_ptr;
        if (ctrl->wbuf_id != 0) {
            mutex_exit(&oplmsu_uinst->c_lock);
            return;
        }

        ctrl->wbuftbl->q = q;
        ctrl->wbuftbl->rw_flag = rw_flag;
        ctrl->wbuf_id = bufcall(size, BPRI_LO, oplmsu_cmn_bufcb,
            (void *)ctrl->wbuftbl);

        if (ctrl->wbuf_id == 0) {
            if (ctrl->wtout_id != 0) {
                mutex_exit(&oplmsu_uinst->c_lock);
                return;
            }

            ctrl->wtout_id = timeout(oplmsu_cmn_bufcb,
                (void *)ctrl->wbuftbl, drv_usectohz(MSU_TM_500MS));
        }
        mutex_exit(&oplmsu_uinst->c_lock);
    } else if (rw_flag == MSU_READ_SIDE) {
        lpath_t *lpath;
        mblk_t  *wrk_msg;

        mutex_enter(&oplmsu_uinst->l_lock);
        lpath = (lpath_t *)q->q_ptr;
        if (mp->b_datap->db_type >= QPCTL) {
            if (lpath->first_lpri_hi == NULL) {
                lpath->last_lpri_hi = mp;
                mp->b_next = NULL;
            } else {
                wrk_msg = lpath->first_lpri_hi;
                wrk_msg->b_prev = mp;
                mp->b_next = wrk_msg;
            }
            mp->b_prev = NULL;
            lpath->first_lpri_hi = mp;
        } else {
            (void) putbq(q, mp);
        }

        if (lpath->rbuf_id != 0) {
            mutex_exit(&oplmsu_uinst->l_lock);
            return;
        }

        lpath->rbuftbl->q = q;
        lpath->rbuftbl->rw_flag = rw_flag;
        lpath->rbuf_id = bufcall(size, BPRI_LO, oplmsu_cmn_bufcb,
            (void *)lpath->rbuftbl);

        if (lpath->rbuf_id == 0) {
            if (lpath->rtout_id != 0) {
                mutex_exit(&oplmsu_uinst->l_lock);
                return;
            }

            lpath->rtout_id = timeout(oplmsu_cmn_bufcb,
                (void *)lpath->rbuftbl, drv_usectohz(MSU_TM_500MS));
        }
        mutex_exit(&oplmsu_uinst->l_lock);
    }
}

/*
 * Previous sequence for active path change
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_cmn_prechg(queue_t *q, mblk_t *mp, int rw_flag, mblk_t **term_mp,
    int *term_ioctl, int *term_stat)
{

    ASSERT(RW_READ_HELD(&oplmsu_uinst->lock));

    if (oplmsu_uinst->tcsets_p != NULL) {
        struct iocblk   *iocp;

        if (oplmsu_cmn_copymb(q, mp, term_mp, oplmsu_uinst->tcsets_p,
            rw_flag) == -1) {
            return (FAILURE);
        }

        iocp = (struct iocblk *)(*term_mp)->b_rptr;
        *term_ioctl = iocp->ioc_cmd;
        *term_stat = MSU_WTCS_ACK;
    } else if (oplmsu_uinst->tiocmset_p != NULL) {
        if (oplmsu_cmn_copymb(q, mp, term_mp, oplmsu_uinst->tiocmset_p,
            rw_flag) == -1) {
            return (FAILURE);
        }

        *term_ioctl = TIOCMSET;
        *term_stat = MSU_WTMS_ACK;
    } else if (oplmsu_uinst->tiocspps_p != NULL) {
        if (oplmsu_cmn_copymb(q, mp, term_mp, oplmsu_uinst->tiocspps_p,
            rw_flag) == -1) {
            return (FAILURE);
        }

        *term_ioctl = TIOCSPPS;
        *term_stat = MSU_WPPS_ACK;
    } else if (oplmsu_uinst->tiocswinsz_p != NULL) {
        if (oplmsu_cmn_copymb(q, mp, term_mp,
            oplmsu_uinst->tiocswinsz_p, rw_flag) == -1) {
            return (FAILURE);
        }

        *term_ioctl = TIOCSWINSZ;
        *term_stat = MSU_WWSZ_ACK;
    } else if (oplmsu_uinst->tiocssoftcar_p != NULL) {
        if (oplmsu_cmn_copymb(q, mp, term_mp,
            oplmsu_uinst->tiocssoftcar_p, rw_flag) == -1) {
            return (FAILURE);
        }

        *term_ioctl = TIOCSSOFTCAR;
        *term_stat = MSU_WCAR_ACK;
    } else {
        *term_stat = MSU_WPTH_CHG;
        *term_mp = NULL;
    }
    return (SUCCESS);
}

/*
 * Pick up termios to re-set
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : A
 */
int
oplmsu_stop_prechg(mblk_t **term_mp, int *term_ioctl, int *term_stat)
{

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));

    if (oplmsu_uinst->tcsets_p != NULL) {
        struct iocblk   *iocp;

        if ((*term_mp = copymsg(oplmsu_uinst->tcsets_p)) == NULL) {
            return (FAILURE);
        }

        iocp = (struct iocblk *)(*term_mp)->b_rptr;
        *term_ioctl = iocp->ioc_cmd;
        *term_stat = MSU_WTCS_ACK;
    } else if (oplmsu_uinst->tiocmset_p != NULL) {
        if ((*term_mp = copymsg(oplmsu_uinst->tiocmset_p)) == NULL) {
            return (FAILURE);
        }

        *term_ioctl = TIOCMSET;
        *term_stat = MSU_WTMS_ACK;
    } else if (oplmsu_uinst->tiocspps_p != NULL) {
        if ((*term_mp = copymsg(oplmsu_uinst->tiocspps_p)) == NULL) {
            return (FAILURE);
        }

        *term_ioctl = TIOCSPPS;
        *term_stat = MSU_WPPS_ACK;
    } else if (oplmsu_uinst->tiocswinsz_p != NULL) {
        if ((*term_mp = copymsg(oplmsu_uinst->tiocswinsz_p)) == NULL) {
            return (FAILURE);
        }

        *term_ioctl = TIOCSWINSZ;
        *term_stat = MSU_WWSZ_ACK;
    } else if (oplmsu_uinst->tiocssoftcar_p != NULL) {
        if ((*term_mp = copymsg(oplmsu_uinst->tiocssoftcar_p))
            == NULL) {
            return (FAILURE);
        }

        *term_ioctl = TIOCSSOFTCAR;
        *term_stat = MSU_WCAR_ACK;
    } else {
        *term_stat = MSU_WPTH_CHG;
        *term_mp = NULL;
    }
    return (SUCCESS);
}

/*
 * Previous sequence for active path change termio
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_cmn_prechg_termio(queue_t *q, mblk_t *mp, int rw_flag, int prev_flag,
    mblk_t **term_mp, int *term_stat)
{

    ASSERT(RW_READ_HELD(&oplmsu_uinst->lock));

    if ((prev_flag == MSU_TIOS_TCSETS) &&
        (oplmsu_uinst->tiocmset_p != NULL)) {
        if (oplmsu_cmn_copymb(q, mp, term_mp, oplmsu_uinst->tiocmset_p,
            rw_flag) == FAILURE) {
            return (FAILURE);
        }

        *term_stat = MSU_WTMS_ACK;
    } else if ((prev_flag <= MSU_TIOS_MSET) &&
        (oplmsu_uinst->tiocspps_p != NULL)) {
        if (oplmsu_cmn_copymb(q, mp, term_mp, oplmsu_uinst->tiocspps_p,
            rw_flag) == FAILURE) {
            return (FAILURE);
        }

        *term_stat = MSU_WPPS_ACK;
    } else if ((prev_flag <= MSU_TIOS_PPS) &&
        (oplmsu_uinst->tiocswinsz_p != NULL)) {
        if (oplmsu_cmn_copymb(q, mp, term_mp,
            oplmsu_uinst->tiocswinsz_p, rw_flag) == FAILURE) {
            return (FAILURE);
        }

        *term_stat = MSU_WWSZ_ACK;
    } else if ((prev_flag <= MSU_TIOS_WINSZP) &&
        (oplmsu_uinst->tiocssoftcar_p != NULL)) {
        if (oplmsu_cmn_copymb(q, mp, term_mp,
            oplmsu_uinst->tiocssoftcar_p, rw_flag) == FAILURE) {
            return (FAILURE);
        }

        *term_stat = MSU_WCAR_ACK;
    } else if (prev_flag <= MSU_TIOS_SOFTCAR) {
        *term_mp = NULL;
        *term_stat = MSU_WPTH_CHG;
    }
    return (SUCCESS);
}

/*
 * Pull up messages
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : P
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_cmn_pullup_msg(queue_t *q, mblk_t *mp)
{
    mblk_t  *nmp = NULL;

    if ((mp != NULL) && (mp->b_cont != NULL) &&
        (mp->b_cont->b_cont != NULL)) {
        if ((nmp = msgpullup(mp->b_cont, -1)) == NULL) {
            oplmsu_iocack(q, mp, ENOSR);
            return (FAILURE);
        } else {
            freemsg(mp->b_cont);
            mp->b_cont = nmp;
        }
    }
    return (SUCCESS);
}

/*
 * Wake up flow control
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_cmn_wakeup(queue_t *q)
{
    ctrl_t  *ctrl;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));

    mutex_enter(&oplmsu_uinst->c_lock);
    ctrl = (ctrl_t *)q->q_ptr;
    if (ctrl->sleep_flag == CV_SLEEP) {
        ctrl->sleep_flag = CV_WAKEUP;
        cv_signal(&ctrl->cvp);
    }
    mutex_exit(&oplmsu_uinst->c_lock);
}

/*
 * bufcall() and timeout() callback entry for read/write stream
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : P
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_cmn_bufcb(void *arg)
{
    struct buf_tbl  *buftbl = arg;
    lpath_t     *lpath;
    ctrl_t      *ctrl;
    queue_t     *q;
    int     lq_flag = 0;

    rw_enter(&oplmsu_uinst->lock, RW_WRITER);
    mutex_enter(&oplmsu_uinst->l_lock);

    lpath = oplmsu_uinst->first_lpath;
    while (lpath) {
        if ((buftbl == lpath->rbuftbl) &&
            (buftbl->rw_flag == MSU_READ_SIDE)) {
            if ((lpath->rbuf_id == 0) && (lpath->rtout_id == 0)) {
                mutex_exit(&oplmsu_uinst->l_lock);
                rw_exit(&oplmsu_uinst->lock);
            } else {
                q = lpath->rbuftbl->q;
                lpath->rbuftbl->q = NULL;
                lpath->rbuftbl->rw_flag = UNDEFINED;

                if (lpath->rbuf_id) {
                    lpath->rbuf_id = 0;
                } else {
                    lpath->rtout_id = 0;
                }
                mutex_exit(&oplmsu_uinst->l_lock);

                if (oplmsu_queue_flag == 1) {
                    lq_flag = 1;
                    oplmsu_queue_flag = 0;
                }

                rw_exit(&oplmsu_uinst->lock);
                oplmsu_rcmn_high_qenable(q);

                if (lq_flag == 1) {
                    rw_enter(&oplmsu_uinst->lock,
                        RW_WRITER);
                    oplmsu_queue_flag = 1;
                    rw_exit(&oplmsu_uinst->lock);
                }
            }
            return;
        }
        lpath = lpath->l_next;
    }
    mutex_exit(&oplmsu_uinst->l_lock);

    mutex_enter(&oplmsu_uinst->c_lock);
    if ((ctrl = oplmsu_uinst->user_ctrl) != NULL) {
        if ((buftbl == ctrl->wbuftbl) &&
            (buftbl->rw_flag == MSU_WRITE_SIDE)) {
            oplmsu_wbufcb_posthndl(ctrl);
            mutex_exit(&oplmsu_uinst->c_lock);
            rw_exit(&oplmsu_uinst->lock);
            return;
        }
    }

    if ((ctrl = oplmsu_uinst->meta_ctrl) != NULL) {
        if ((buftbl == ctrl->wbuftbl) &&
            (buftbl->rw_flag == MSU_WRITE_SIDE)) {
            oplmsu_wbufcb_posthndl(ctrl);
            mutex_exit(&oplmsu_uinst->c_lock);
            rw_exit(&oplmsu_uinst->lock);
            return;
        }
    }
    mutex_exit(&oplmsu_uinst->c_lock);
    rw_exit(&oplmsu_uinst->lock);
}

/*
 * bufcall() or timeout() callback post handling for write stream
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_WRITER]
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : M
 */
void
oplmsu_wbufcb_posthndl(ctrl_t *ctrl)
{
    queue_t *q;
    int lq_flag = 0;

    ASSERT(RW_WRITE_HELD(&oplmsu_uinst->lock));
    ASSERT(MUTEX_HELD(&oplmsu_uinst->c_lock));

    if ((ctrl->wbuf_id == 0) && (ctrl->wtout_id == 0)) {
        return;
    }

    q = ctrl->wbuftbl->q;
    ctrl->wbuftbl->q = NULL;
    ctrl->wbuftbl->rw_flag = UNDEFINED;
    if (ctrl->wbuf_id) {
        ctrl->wbuf_id = 0;
    } else {
        ctrl->wtout_id = 0;
    }

    if (oplmsu_queue_flag == 1) {
        lq_flag = 1;
        oplmsu_queue_flag = 0;
    }

    mutex_exit(&oplmsu_uinst->c_lock);
    oplmsu_wcmn_high_qenable(q, RW_WRITER);
    mutex_enter(&oplmsu_uinst->c_lock);

    if (lq_flag == 1) {
        oplmsu_queue_flag = 1;
    }
}

/*
 *  COMMON FUNCTIONS FOR WRITE STREAM
 */

/*
 * Check control node and driver privilege
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_wcmn_chknode(queue_t *q, int node, mblk_t *mp)
{
    struct iocblk   *iocp;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));

    mutex_enter(&oplmsu_uinst->c_lock);
    if (((ctrl_t *)q->q_ptr)->node_type != node) {
        mutex_exit(&oplmsu_uinst->c_lock);
        cmn_err(CE_WARN, "oplmsu: chk-node: ctrl node type = %d", node);
        return (EINVAL);
    }
    mutex_exit(&oplmsu_uinst->c_lock);

    /* Check super-user by oplmsu.conf */
    if (oplmsu_check_su != 0) {
        iocp = (struct iocblk *)mp->b_rptr;
        if (drv_priv(iocp->ioc_cr) != 0) {
            cmn_err(CE_WARN, "oplmsu: chk-node: Permission denied");
            return (EPERM);
        }
    }
    return (SUCCESS);
}

/*
 * Flush handle for write side stream
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_wcmn_flush_hndl(queue_t *q, mblk_t *mp, krw_t rw)
{
    queue_t *dst_queue = NULL;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));

    if (*mp->b_rptr & FLUSHW) { /* Write side */
        flushq(q, FLUSHDATA);
    }

    dst_queue = oplmsu_uinst->lower_queue;
    if (dst_queue == NULL) {
        if (*mp->b_rptr & FLUSHR) {
            flushq(RD(q), FLUSHDATA);
            *mp->b_rptr &= ~FLUSHW;

            rw_exit(&oplmsu_uinst->lock);
            OPLMSU_TRACE(q, mp, MSU_TRC_UO);
            qreply(q, mp);
            rw_enter(&oplmsu_uinst->lock, rw);
        } else {
            freemsg(mp);
        }
    } else {
        (void) putq(WR(dst_queue), mp);
    }
}

/*
 * Through message handle for write side stream
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_wcmn_through_hndl(queue_t *q, mblk_t *mp, int pri_flag, krw_t rw)
{
    queue_t *usr_queue = NULL, *dst_queue = NULL;
    ctrl_t  *ctrl;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));

    mutex_enter(&oplmsu_uinst->c_lock);
    if ((ctrl = oplmsu_uinst->user_ctrl) != NULL) {
        usr_queue = ctrl->queue;
        mutex_exit(&oplmsu_uinst->c_lock);
    } else {
        mutex_exit(&oplmsu_uinst->c_lock);
        if (mp->b_datap->db_type == M_IOCTL) {
            rw_exit(&oplmsu_uinst->lock);
            oplmsu_iocack(q, mp, ENODEV);
            rw_enter(&oplmsu_uinst->lock, rw);
        } else {
            freemsg(mp);
        }
        return (SUCCESS);
    }

    if (oplmsu_uinst->lower_queue != NULL) {
        dst_queue = WR(oplmsu_uinst->lower_queue);
    } else {
        cmn_err(CE_WARN, "!oplmsu: through-lwq: "
            "Active path doesn't exist");

        if (mp->b_datap->db_type == M_IOCTL) {
            rw_exit(&oplmsu_uinst->lock);
            oplmsu_iocack(q, mp, ENODEV);
            rw_enter(&oplmsu_uinst->lock, rw);
        } else {
            freemsg(mp);
        }
        return (SUCCESS);
    }

    if ((usr_queue == WR(q)) || (usr_queue == RD(q))) {
        if (pri_flag == MSU_HIGH) {
            (void) putq(dst_queue, mp);
        } else {
            if (canput(dst_queue)) {
                (void) putq(dst_queue, mp);
            } else {
                oplmsu_wcmn_norm_putbq(WR(q), mp, dst_queue);
                return (FAILURE);
            }
        }
    } else {
        cmn_err(CE_WARN, "oplmsu: through-lwq: "
            "Inappropriate message for this node");

        if (mp->b_datap->db_type == M_IOCTL) {
            rw_exit(&oplmsu_uinst->lock);
            oplmsu_iocack(q, mp, ENODEV);
            rw_enter(&oplmsu_uinst->lock, rw);
        } else {
            freemsg(mp);
        }
    }
    return (SUCCESS);
}

/*
 * Get high priority message from buffer for upper write stream
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : A
 *  -. uinst_t->c_lock : P
 */
mblk_t *
oplmsu_wcmn_high_getq(queue_t *uwq)
{
    mblk_t  *mp;
    ctrl_t  *ctrl;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));

    mutex_enter(&oplmsu_uinst->c_lock);
    ctrl = (ctrl_t *)uwq->q_ptr;
    mp = ctrl->first_upri_hi;
    if (mp != NULL) {
        if (mp->b_next == NULL) {
            ctrl->first_upri_hi = NULL;
            ctrl->last_upri_hi = NULL;
        } else {
            ctrl->first_upri_hi = mp->b_next;
            mp->b_next->b_prev = NULL;
            mp->b_next = NULL;
        }
        mp->b_prev = NULL;
    }
    mutex_exit(&oplmsu_uinst->c_lock);
    return (mp);
}

/*
 * putbq() function for normal priority message of write stream
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_wcmn_norm_putbq(queue_t *uwq, mblk_t *mp, queue_t *dq)
{
    lpath_t *lpath;

    ASSERT(mp != NULL);
    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));

    mutex_enter(&oplmsu_uinst->l_lock);
    lpath = (lpath_t *)dq->q_ptr;
    lpath->uwq_flag = 1;
    lpath->uwq_queue = uwq;
    mutex_exit(&oplmsu_uinst->l_lock);
    (void) putbq(uwq, mp);
}

/*
 * Restart queuing for high priority message of write stream when flow control
 * failed
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER or RW_WRITER]
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_wcmn_high_qenable(queue_t *q, krw_t rw)
{
    mblk_t  *mp;

    ASSERT(RW_LOCK_HELD(&oplmsu_uinst->lock));

    if (oplmsu_queue_flag == 1) {
        return;
    }

    /* Handle high priority message */
    while (mp = oplmsu_wcmn_high_getq(WR(q))) {
        if (mp->b_datap->db_type & M_FLUSH) {
            oplmsu_wcmn_flush_hndl(q, mp, rw);
            continue;
        }

        if (oplmsu_wcmn_through_hndl(q, mp, MSU_HIGH, rw) == FAILURE) {
            return;
        }
    }
    qenable(WR(q)); /* enable upper write queue */
}

/*
 *  COMMON FUNCTIONS FOR READ STREAM
 */

/*
 * Flush handle for read side stream
 *
 * Requires lock ( M: mandatory  P: prohibited  A: allowed
 *  -. uinst_t->lock   : M [RW_READER]
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_rcmn_flush_hndl(queue_t *q, mblk_t *mp)
{
    queue_t *dst_queue = NULL;
    ctrl_t  *ctrl;

    ASSERT(RW_READ_HELD(&oplmsu_uinst->lock));

    if (*mp->b_rptr & FLUSHR) {
        /* Remove only data messages from read queue */
        flushq(q, FLUSHDATA);
    }

    mutex_enter(&oplmsu_uinst->c_lock);
    if ((ctrl = oplmsu_uinst->user_ctrl) != NULL) {
        dst_queue = RD(ctrl->queue);
        mutex_exit(&oplmsu_uinst->c_lock);

        if (dst_queue != NULL) {
            (void) putq(dst_queue, mp);
        } else {
            if (*mp->b_rptr & FLUSHW) {
                flushq(WR(q), FLUSHDATA);
                *mp->b_rptr &= ~FLUSHR;

                rw_exit(&oplmsu_uinst->lock);
                OPLMSU_TRACE(q, mp, MSU_TRC_LO);
                qreply(q, mp);
                rw_enter(&oplmsu_uinst->lock, RW_READER);
            } else {
                freemsg(mp);
            }
        }
    } else {
        mutex_exit(&oplmsu_uinst->c_lock);
        if (*mp->b_rptr & FLUSHW) {
            flushq(WR(q), FLUSHDATA);
            *mp->b_rptr &= ~FLUSHR;

            rw_exit(&oplmsu_uinst->lock);
            OPLMSU_TRACE(q, mp, MSU_TRC_LO);
            qreply(q, mp);
            rw_enter(&oplmsu_uinst->lock, RW_READER);
        } else {
            freemsg(mp);
        }
    }
}

/*
 * Through message handle for read side stream
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : M [RW_READER]
 *  -. uinst_t->u_lock : A
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
int
oplmsu_rcmn_through_hndl(queue_t *q, mblk_t *mp, int pri_flag)
{
    lpath_t *lpath;
    ctrl_t  *ctrl;
    queue_t *dst_queue = NULL;
    int act_flag;

    ASSERT(RW_READ_HELD(&oplmsu_uinst->lock));

    mutex_enter(&oplmsu_uinst->l_lock);
    lpath = (lpath_t *)q->q_ptr;
    if (lpath->uinst != NULL) {
        act_flag = ACTIVE_RES;
    } else {
        act_flag = NOT_ACTIVE_RES;
    }
    mutex_exit(&oplmsu_uinst->l_lock);

    mutex_enter(&oplmsu_uinst->c_lock);
    if (((ctrl = oplmsu_uinst->user_ctrl) != NULL) &&
        (((mp->b_datap->db_type == M_IOCACK) ||
        (mp->b_datap->db_type == M_IOCNAK)) || (act_flag == ACTIVE_RES))) {
        dst_queue = RD(ctrl->queue);
    } else {
        mutex_exit(&oplmsu_uinst->c_lock);
        freemsg(mp);
        return (SUCCESS);
    }

    if (pri_flag == MSU_HIGH) {
        (void) putq(dst_queue, mp);
    } else {
        if (canput(dst_queue)) {
            (void) putq(dst_queue, mp);
        } else {
            /*
             * Place a normal priority message at the head of
             * read queue
             */

            ctrl = (ctrl_t *)dst_queue->q_ptr;
            ctrl->lrq_flag = 1;
            ctrl->lrq_queue = q;
            mutex_exit(&oplmsu_uinst->c_lock);
            (void) putbq(q, mp);
            return (FAILURE);
        }
    }
    mutex_exit(&oplmsu_uinst->c_lock);
    return (SUCCESS);
}

/*
 * Restart queuing for high priority message of read stream
 * when flow control failed
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : P
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_rcmn_high_qenable(queue_t *q)
{
    mblk_t      *mp;
    struct iocblk   *iocp = NULL;
    lpath_t     *lpath;
    int     rval;

    rw_enter(&oplmsu_uinst->lock, RW_READER);

    for (;;) {  /* Handle high priority message */
        mutex_enter(&oplmsu_uinst->l_lock);
        lpath = (lpath_t *)q->q_ptr;
        if ((mp = lpath->first_lpri_hi) == NULL) {
            mutex_exit(&oplmsu_uinst->l_lock);
            break;
        }

        if (mp->b_next == NULL) {
            lpath->first_lpri_hi = NULL;
            lpath->last_lpri_hi = NULL;
        } else {
            lpath->first_lpri_hi = mp->b_next;
            mp->b_next->b_prev = NULL;
            mp->b_next = NULL;
        }
        mp->b_prev = NULL;
        mutex_exit(&oplmsu_uinst->l_lock);

        rval = SUCCESS;
        switch (mp->b_datap->db_type) {
        case M_IOCACK :     /* FALLTHRU */
        case M_IOCNAK :
            iocp = (struct iocblk *)mp->b_rptr;
            switch (iocp->ioc_cmd) {
            case TCSETS :       /* FALLTHRU */
            case TCSETSW :      /* FALLTHRU */
            case TCSETSF :      /* FALLTHRU */
            case TIOCMSET :     /* FALLTHRU */
            case TIOCSPPS :     /* FALLTHRU */
            case TIOCSWINSZ :   /* FALLTHRU */
            case TIOCSSOFTCAR :
                rw_exit(&oplmsu_uinst->lock);
                rval = oplmsu_lrioctl_termios(q, mp);
                rw_enter(&oplmsu_uinst->lock, RW_WRITER);
                break;

            default :
                rval = oplmsu_rcmn_through_hndl(
                    q, mp, MSU_HIGH);
                if (rval == FAILURE) {
                    rw_exit(&oplmsu_uinst->lock);
                    return;
                }
            }
            break;

        case M_ERROR :
            rw_exit(&oplmsu_uinst->lock);
            rval = oplmsu_lrmsg_error(q, mp);
            rw_enter(&oplmsu_uinst->lock, RW_WRITER);
            break;

        case M_FLUSH :
            oplmsu_rcmn_flush_hndl(q, mp);
            break;

        default :
            rval = oplmsu_rcmn_through_hndl(q, mp, MSU_HIGH);
            if (rval == FAILURE) {
                rw_exit(&oplmsu_uinst->lock);
                return;
            }
        }

        if (rval == FAILURE) {
            break;
        }
    }

    rw_exit(&oplmsu_uinst->lock);
    qenable(q); /* Enable lower read queue */
}

#ifdef DEBUG
/*
 * Online trace
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : P
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_cmn_trace(queue_t *q, mblk_t *mp, int op)
{
    struct iocblk   *iocp;

    if ((op < MSU_TRC_UI) || (op > MSU_TRC_CLS)) {
        return;
    }

    mutex_enter(&oplmsu_ltrc_lock);

    if (oplmsu_debug_mode & MSU_DPRINT_ON) {
        oplmsu_cmn_msglog(mp, op);
    }

    /* Trace current counter */
    (void) drv_getparm(LBOLT, (void *)&oplmsu_ltrc_ccnt);

    if (oplmsu_ltrc_cur == oplmsu_ltrc_tail) {
        oplmsu_ltrc_cur = oplmsu_ltrc_top;
    } else {
        oplmsu_ltrc_cur++;
    }
    oplmsu_ltrc_cur->q = q;
    oplmsu_ltrc_cur->mp = mp;

    switch (op) {
    case MSU_TRC_UI :
        oplmsu_ltrc_cur->op[0] = 'u';
        oplmsu_ltrc_cur->op[1] = 'i';
        break;

    case MSU_TRC_UO :
        oplmsu_ltrc_cur->op[0] = 'u';
        oplmsu_ltrc_cur->op[1] = 'o';
        break;

    case MSU_TRC_LI :
        oplmsu_ltrc_cur->op[0] = 'l';
        oplmsu_ltrc_cur->op[1] = 'i';
        break;

    case MSU_TRC_LO :
        oplmsu_ltrc_cur->op[0] = 'l';
        oplmsu_ltrc_cur->op[1] = 'o';
        break;

    case MSU_TRC_OPN :
        oplmsu_ltrc_cur->op[0] = 'o';
        oplmsu_ltrc_cur->op[1] = 'p';
        break;

    case MSU_TRC_CLS :
        oplmsu_ltrc_cur->op[0] = 'c';
        oplmsu_ltrc_cur->op[1] = 'l';
        break;
    }

    if ((op == MSU_TRC_LI) || (op == MSU_TRC_LO)) {
        mutex_enter(&oplmsu_uinst->l_lock);
        oplmsu_ltrc_cur->pathno = ((lpath_t *)q->q_ptr)->path_no;
        mutex_exit(&oplmsu_uinst->l_lock);
    } else {
        oplmsu_ltrc_cur->pathno = 0;
    }

    if ((op == MSU_TRC_OPN) || (op == MSU_TRC_CLS)) {
        oplmsu_ltrc_cur->msg_type = 0;
        oplmsu_ltrc_cur->msg_cmd = 0;
        oplmsu_ltrc_cur->data = 0;

        switch ((ulong_t)mp) {
        case MSU_NODE_USER :
            oplmsu_ltrc_cur->data = MSU_TRC_USER;
            break;

        case MSU_NODE_META :
            oplmsu_ltrc_cur->data = MSU_TRC_META;
            break;
        }
        oplmsu_ltrc_cur->mp = NULL;
    } else {
        oplmsu_ltrc_cur->msg_type = mp->b_datap->db_type;
        iocp = (struct iocblk *)mp->b_rptr;
        oplmsu_ltrc_cur->msg_cmd = iocp->ioc_cmd;

        if ((mp->b_datap->db_type == M_IOCTL) ||
            (mp->b_datap->db_type == M_IOCACK) ||
            (mp->b_datap->db_type == M_IOCNAK)) {
            oplmsu_ltrc_cur->msg_cmd = iocp->ioc_cmd;

            if (mp->b_cont != NULL) {
                oplmsu_ltrc_cur->data =
                    (ulong_t)mp->b_cont->b_rptr;
            } else {
                oplmsu_ltrc_cur->data = 0;
            }
        } else {
            oplmsu_ltrc_cur->msg_cmd = 0;

            if (mp->b_rptr == NULL) {
                oplmsu_ltrc_cur->data = 0;
            } else {
                oplmsu_ltrc_cur->data = *(ulong_t *)mp->b_rptr;
            }
        }
    }
    mutex_exit(&oplmsu_ltrc_lock);
}

/*
 * Display message log to console
 *
 * Requires Lock (( M: Mandatory, P: Prohibited, A: Allowed ))
 *  -. uinst_t->lock   : P
 *  -. uinst_t->u_lock : P
 *  -. uinst_t->l_lock : P
 *  -. uinst_t->c_lock : P
 */
void
oplmsu_cmn_msglog(mblk_t *mp, int direction)
{
    uchar_t *cur = NULL;
    mblk_t  *tmp_mp = NULL;
    ulong_t len;
    ulong_t line;
    ulong_t col;
    ulong_t row;
    ulong_t count;
    char    buffer[70];
    char    *bufp;

    if (mp == NULL) {
        return;
    }

    switch (direction) {
    case 0:
        cmn_err(CE_NOTE, "!---------- Upper in --------");
        break;

    case 1:
        cmn_err(CE_NOTE, "!---------- Upper out -------");
        break;

    case 2:
        cmn_err(CE_NOTE, "!---------- Lower in --------");
        break;

    case 3:
        cmn_err(CE_NOTE, "!---------- Lower out -------");
        break;

    default:
        return;
    }

    for (tmp_mp = mp; tmp_mp; tmp_mp = tmp_mp->b_cont) {
        cmn_err(CE_NOTE, "!db_type = 0x%02x", tmp_mp->b_datap->db_type);

        len = tmp_mp->b_wptr - tmp_mp->b_rptr;
        line = (len + 31) / 32;
        cur = (uchar_t *)tmp_mp->b_rptr;
        count = 0;

        for (col = 0; col < line; col++) {
            bufp = buffer;

            for (row = 0; row < 32; row++) {
                if (row != 0 && (row % 8) == 0) {
                    *bufp = ' ';
                    bufp++;
                }
                (void) sprintf(bufp, "%02x", *cur);
                bufp += 2;
                cur++;
                count++;

                if (count >= len) {
                    break;
                }
            }
            *bufp = '\0';
            cmn_err(CE_NOTE, "!%s", buffer);

            if (count >= len) {
                break;
            }
        }
    }
}

void
oplmsu_cmn_prt_pathname(dev_info_t *dip)
{
    char    pathname[128];
    char    wrkbuf[128];

    (void) ddi_pathname(dip, wrkbuf);
    *(wrkbuf + strlen(wrkbuf)) = '\0';
    (void) sprintf(pathname, "/devices%s:%c", wrkbuf,
        'a'+ ddi_get_instance(dip));

    DBG_PRINT((CE_NOTE, "oplmsu: debug-info: "
        "Active path change to path => %s", pathname));
}
#endif