/*
 * 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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright 2019, Joyent, Inc.
 * Copyright 2022 Garrett D'Amore
 * Copyright 2025 Oxide Computer Company
 */

/*
 * Softmac data-path switching:
 *
 * - Fast-path model
 *
 * When the softmac fast-path is used, a dedicated lower-stream
 * will be opened over the legacy device for each IP/ARP (upper-)stream
 * over the softMAC, and all DLPI messages (including control messages
 * and data messages) will be exchanged between the upper-stream and
 * the corresponding lower-stream directly. Therefore, the data
 * demultiplexing, filtering and classification processing will be done
 * by the lower-stream, and the GLDv3 DLS/MAC layer processing will be
 * no longer needed.
 *
 * - Slow-path model
 *
 * Some GLDv3 features requires the GLDv3 DLS/MAC layer processing to
 * not be bypassed to assure its function correctness. For example,
 * softmac fast-path must be disabled to support GLDv3 VNIC functionality.
 * In this case, a shared lower-stream will be opened over the legacy
 * device, which is responsible for implementing the GLDv3 callbacks
 * and passing RAW data messages between the legacy devices and the GLDv3
 * framework.
 *
 * By default, the softmac fast-path mode will be used to assure the
 * performance; MAC clients will be able to request to disable the softmac
 * fast-path mode to support certain features, and if that succeeds,
 * the system will fallback to the slow-path softmac data-path model.
 *
 *
 * The details of the softmac data fast-path model is stated as below
 *
 * 1. When a stream is opened on a softMAC, the softmac module will takes
 *    over the DLPI processing on this stream;
 *
 * 2. For IP/ARP streams over a softMAC, softmac data fast-path will be
 *    used by default, unless fast-path is disabled by any MAC client
 *    explicitly. The softmac module first identifies an IP/ARP stream
 *    by seeing whether there is a SIOCSLIFNAME ioctl sent from upstream,
 *    if there is one, this stream is either an IP or an ARP stream
 *    and will use fast-path potentially;
 *
 * 3. When the softmac fast-path is used, an dedicated lower-stream will
 *    be setup for each IP/ARP stream (1-1 mapping). From that point on,
 *    all control and data messages will be exchanged between the IP/ARP
 *    upper-stream and the legacy device through this dedicated
 *    lower-stream. As a result, the DLS/MAC layer processing in GLDv3
 *    will be skipped, and this greatly improves the performance;
 *
 * 4. When the softmac data fast-path is disabled by a MAC client (e.g.,
 *    by a VNIC), all the IP/ARP upper streams will try to switch from
 *    the fast-path to the slow-path. The dedicated lower-stream will be
 *    destroyed, and all the control and data-messages will go through the
 *    existing GLDv3 code path and (in the end) the shared lower-stream;
 *
 * 5. On the other hand, when the last MAC client cancels its fast-path
 *    disable request, all the IP/ARP streams will try to switch back to
 *    the fast-path mode;
 *
 * Step 5 and 6 both rely on the data-path mode switching process
 * described below:
 *
 * 1) To switch the softmac data-path mode (between fast-path and slow-path),
 *    softmac will first send a DL_NOTE_REPLUMB DL_NOTIFY_IND message
 *    upstream over each IP/ARP streams that needs data-path mode switching;
 *
 * 2) When IP receives this DL_NOTE_REPLUMB message, it will bring down
 *    all the IP interfaces on the corresponding ill (IP Lower level
 *    structure), and bring up those interfaces over again; this will in
 *    turn cause the ARP to "replumb" the interface.
 *
 *    During the replumb process, both IP and ARP will send downstream the
 *    necessary DL_DISABMULTI_REQ and DL_UNBIND_REQ messages and cleanup
 *    the old state of the underlying softMAC, following with the necessary
 *    DL_BIND_REQ and DL_ENABMULTI_REQ messages to setup the new state.
 *    Between the cleanup and re-setup process, IP/ARP will also send down
 *    a DL_NOTE_REPLUMB_DONE DL_NOTIFY_CONF messages to the softMAC to
 *    indicate the *switching point*;
 *
 * 3) When softmac receives the DL_NOTE_REPLUMB_DONE message, it either
 *    creates or destroys the dedicated lower-stream (depending on which
 *    data-path mode the softMAC switches to), and change the softmac
 *    data-path mode. From then on, softmac will process all the succeeding
 *    control messages (including the DL_BIND_REQ and DL_ENABMULTI_REQ
 *    messages) and data messages based on new data-path mode.
 */

#include <sys/types.h>
#include <sys/disp.h>
#include <sys/callb.h>
#include <sys/sysmacros.h>
#include <sys/file.h>
#include <sys/vlan.h>
#include <sys/dld.h>
#include <sys/sockio.h>
#include <sys/softmac_impl.h>
#include <net/if.h>

static kmutex_t         softmac_taskq_lock;
static kthread_t        *softmac_taskq_thread;
static kcondvar_t       softmac_taskq_cv;
static list_t           softmac_taskq_list;     /* List of softmac_upper_t */
boolean_t               softmac_taskq_quit;
boolean_t               softmac_taskq_done;

static void             softmac_taskq_dispatch();
static int              softmac_fastpath_setup(softmac_upper_t *);
static mac_tx_cookie_t  softmac_fastpath_wput_data(softmac_upper_t *, mblk_t *,
                            uintptr_t, uint16_t);
static void             softmac_datapath_switch_done(softmac_upper_t *);

void
softmac_fp_init()
{
        mutex_init(&softmac_taskq_lock, NULL, MUTEX_DRIVER, NULL);
        cv_init(&softmac_taskq_cv, NULL, CV_DRIVER, NULL);

        softmac_taskq_quit = B_FALSE;
        softmac_taskq_done = B_FALSE;
        list_create(&softmac_taskq_list, sizeof (softmac_upper_t),
            offsetof(softmac_upper_t, su_taskq_list_node));
        softmac_taskq_thread = thread_create(NULL, 0, softmac_taskq_dispatch,
            NULL, 0, &p0, TS_RUN, minclsyspri);
}

void
softmac_fp_fini()
{
        /*
         * Request the softmac_taskq thread to quit and wait for it to be done.
         */
        mutex_enter(&softmac_taskq_lock);
        softmac_taskq_quit = B_TRUE;
        cv_signal(&softmac_taskq_cv);
        while (!softmac_taskq_done)
                cv_wait(&softmac_taskq_cv, &softmac_taskq_lock);
        mutex_exit(&softmac_taskq_lock);
        thread_join(softmac_taskq_thread->t_did);
        list_destroy(&softmac_taskq_list);

        mutex_destroy(&softmac_taskq_lock);
        cv_destroy(&softmac_taskq_cv);
}

static boolean_t
check_ip_above(queue_t *q)
{
        queue_t         *next_q;
        boolean_t       ret = B_TRUE;

        claimstr(q);
        next_q = q->q_next;
        if (strcmp(next_q->q_qinfo->qi_minfo->mi_idname, "ip") != 0)
                ret = B_FALSE;
        releasestr(q);
        return (ret);
}

/* ARGSUSED */
static int
softmac_capab_perim(softmac_upper_t *sup, void *data, uint_t flags)
{
        switch (flags) {
        case DLD_ENABLE:
                mutex_enter(&sup->su_mutex);
                break;
        case DLD_DISABLE:
                mutex_exit(&sup->su_mutex);
                break;
        case DLD_QUERY:
                return (MUTEX_HELD(&sup->su_mutex));
        }
        return (0);
}

static mac_tx_notify_handle_t
softmac_client_tx_notify(softmac_upper_t *sup, mac_tx_notify_t func, void *arg)
{
        ASSERT(MUTEX_HELD(&sup->su_mutex));

        if (func != NULL) {
                sup->su_tx_notify_func = func;
                sup->su_tx_notify_arg = arg;
        } else {
                /*
                 * Wait for all tx_notify_func call to be done.
                 */
                while (sup->su_tx_inprocess != 0)
                        cv_wait(&sup->su_cv, &sup->su_mutex);

                sup->su_tx_notify_func = NULL;
                sup->su_tx_notify_arg = NULL;
        }
        return ((mac_tx_notify_handle_t)sup);
}

static boolean_t
softmac_tx_is_flow_blocked(softmac_upper_t *sup, mac_tx_cookie_t cookie)
{
        ASSERT(cookie == (mac_tx_cookie_t)sup);
        return (sup->su_tx_busy);
}

static int
softmac_capab_direct(softmac_upper_t *sup, void *data, uint_t flags)
{
        dld_capab_direct_t      *direct = data;
        softmac_lower_t         *slp = sup->su_slp;

        ASSERT(MUTEX_HELD(&sup->su_mutex));

        ASSERT(sup->su_mode == SOFTMAC_FASTPATH);

        switch (flags) {
        case DLD_ENABLE:
                if (sup->su_direct)
                        return (0);

                sup->su_direct_rxinfo.slr_rx = (softmac_rx_t)direct->di_rx_cf;
                sup->su_direct_rxinfo.slr_arg = direct->di_rx_ch;
                slp->sl_rxinfo = &sup->su_direct_rxinfo;
                direct->di_tx_df = (uintptr_t)softmac_fastpath_wput_data;
                direct->di_tx_dh = sup;
                direct->di_tx_fctl_df = (uintptr_t)softmac_tx_is_flow_blocked;
                direct->di_tx_fctl_dh = sup;
                direct->di_tx_cb_df = (uintptr_t)softmac_client_tx_notify;
                direct->di_tx_cb_dh = sup;
                sup->su_direct = B_TRUE;
                return (0);

        case DLD_DISABLE:
                if (!sup->su_direct)
                        return (0);

                slp->sl_rxinfo = &sup->su_rxinfo;
                sup->su_direct = B_FALSE;
                return (0);
        }
        return (ENOTSUP);
}

static int
softmac_dld_capab(softmac_upper_t *sup, uint_t type, void *data, uint_t flags)
{
        int     err;

        /*
         * Don't enable direct callback capabilities unless the caller is
         * the IP client. When a module is inserted in a stream (_I_INSERT)
         * the stack initiates capability disable, but due to races, the
         * module insertion may complete before the capability disable
         * completes. So we limit the check to DLD_ENABLE case.
         */
        if ((flags == DLD_ENABLE && type != DLD_CAPAB_PERIM) &&
            !check_ip_above(sup->su_rq)) {
                return (ENOTSUP);
        }

        switch (type) {
        case DLD_CAPAB_DIRECT:
                err = softmac_capab_direct(sup, data, flags);
                break;

        case DLD_CAPAB_PERIM:
                err = softmac_capab_perim(sup, data, flags);
                break;

        default:
                err = ENOTSUP;
                break;
        }
        return (err);
}

static void
softmac_capability_advertise(softmac_upper_t *sup, mblk_t *mp)
{
        dl_capability_ack_t     *dlap;
        dl_capability_sub_t     *dlsp;
        t_uscalar_t             subsize;
        uint8_t                 *ptr;
        queue_t                 *q = sup->su_wq;
        mblk_t                  *mp1;
        softmac_t               *softmac = sup->su_softmac;
        boolean_t               dld_capable = B_FALSE;
        boolean_t               hcksum_capable = B_FALSE;
        boolean_t               zcopy_capable = B_FALSE;

        ASSERT(sup->su_mode == SOFTMAC_FASTPATH);

        /*
         * Initially assume no capabilities.
         */
        subsize = 0;

        /*
         * Direct capability negotiation interface between IP and softmac
         */
        if (check_ip_above(sup->su_rq)) {
                dld_capable = B_TRUE;
                subsize += sizeof (dl_capability_sub_t) +
                    sizeof (dl_capab_dld_t);
        }

        /*
         * Check if checksum offload is supported on this MAC.
         */
        if (softmac->smac_capab_flags & MAC_CAPAB_HCKSUM) {
                hcksum_capable = B_TRUE;
                subsize += sizeof (dl_capability_sub_t) +
                    sizeof (dl_capab_hcksum_t);
        }

        /*
         * Check if zerocopy is supported on this interface.
         */
        if (!(softmac->smac_capab_flags & MAC_CAPAB_NO_ZCOPY)) {
                zcopy_capable = B_TRUE;
                subsize += sizeof (dl_capability_sub_t) +
                    sizeof (dl_capab_zerocopy_t);
        }

        /*
         * If there are no capabilities to advertise or if we
         * can't allocate a response, send a DL_ERROR_ACK.
         */
        if ((subsize == 0) || (mp1 = reallocb(mp,
            sizeof (dl_capability_ack_t) + subsize, 0)) == NULL) {
                dlerrorack(q, mp, DL_CAPABILITY_REQ, DL_NOTSUPPORTED, 0);
                return;
        }

        mp = mp1;
        DB_TYPE(mp) = M_PROTO;
        mp->b_wptr = mp->b_rptr + sizeof (dl_capability_ack_t) + subsize;
        bzero(mp->b_rptr, MBLKL(mp));
        dlap = (dl_capability_ack_t *)mp->b_rptr;
        dlap->dl_primitive = DL_CAPABILITY_ACK;
        dlap->dl_sub_offset = sizeof (dl_capability_ack_t);
        dlap->dl_sub_length = subsize;
        ptr = (uint8_t *)&dlap[1];

        /*
         * IP polling interface.
         */
        if (dld_capable) {
                dl_capab_dld_t          dld;

                dlsp = (dl_capability_sub_t *)ptr;
                dlsp->dl_cap = DL_CAPAB_DLD;
                dlsp->dl_length = sizeof (dl_capab_dld_t);
                ptr += sizeof (dl_capability_sub_t);

                bzero(&dld, sizeof (dl_capab_dld_t));
                dld.dld_version = DLD_CURRENT_VERSION;
                dld.dld_capab = (uintptr_t)softmac_dld_capab;
                dld.dld_capab_handle = (uintptr_t)sup;

                dlcapabsetqid(&(dld.dld_mid), sup->su_rq);
                bcopy(&dld, ptr, sizeof (dl_capab_dld_t));
                ptr += sizeof (dl_capab_dld_t);
        }

        /*
         * TCP/IP checksum offload.
         */
        if (hcksum_capable) {
                dl_capab_hcksum_t       hcksum;

                dlsp = (dl_capability_sub_t *)ptr;

                dlsp->dl_cap = DL_CAPAB_HCKSUM;
                dlsp->dl_length = sizeof (dl_capab_hcksum_t);
                ptr += sizeof (dl_capability_sub_t);

                bzero(&hcksum, sizeof (dl_capab_hcksum_t));
                hcksum.hcksum_version = HCKSUM_VERSION_1;
                hcksum.hcksum_txflags = softmac->smac_hcksum_txflags;
                dlcapabsetqid(&(hcksum.hcksum_mid), sup->su_rq);
                bcopy(&hcksum, ptr, sizeof (dl_capab_hcksum_t));
                ptr += sizeof (dl_capab_hcksum_t);
        }

        /*
         * Zero copy
         */
        if (zcopy_capable) {
                dl_capab_zerocopy_t     zcopy;

                dlsp = (dl_capability_sub_t *)ptr;

                dlsp->dl_cap = DL_CAPAB_ZEROCOPY;
                dlsp->dl_length = sizeof (dl_capab_zerocopy_t);
                ptr += sizeof (dl_capability_sub_t);

                bzero(&zcopy, sizeof (dl_capab_zerocopy_t));
                zcopy.zerocopy_version = ZEROCOPY_VERSION_1;
                zcopy.zerocopy_flags = DL_CAPAB_VMSAFE_MEM;
                dlcapabsetqid(&(zcopy.zerocopy_mid), sup->su_rq);
                bcopy(&zcopy, ptr, sizeof (dl_capab_zerocopy_t));
                ptr += sizeof (dl_capab_zerocopy_t);
        }

        ASSERT(ptr == mp->b_rptr + sizeof (dl_capability_ack_t) + subsize);
        qreply(q, mp);
}

static void
softmac_capability_req(softmac_upper_t *sup, mblk_t *mp)
{
        dl_capability_req_t     *dlp = (dl_capability_req_t *)mp->b_rptr;
        dl_capability_sub_t     *sp;
        size_t                  size, len;
        offset_t                off, end;
        t_uscalar_t             dl_err;
        queue_t                 *q = sup->su_wq;

        ASSERT(sup->su_mode == SOFTMAC_FASTPATH);
        if (MBLKL(mp) < sizeof (dl_capability_req_t)) {
                dl_err = DL_BADPRIM;
                goto failed;
        }

        if (!sup->su_bound) {
                dl_err = DL_OUTSTATE;
                goto failed;
        }

        /*
         * This request is overloaded. If there are no requested capabilities
         * then we just want to acknowledge with all the capabilities we
         * support. Otherwise we enable the set of capabilities requested.
         */
        if (dlp->dl_sub_length == 0) {
                softmac_capability_advertise(sup, mp);
                return;
        }

        if (!MBLKIN(mp, dlp->dl_sub_offset, dlp->dl_sub_length)) {
                dl_err = DL_BADPRIM;
                goto failed;
        }

        dlp->dl_primitive = DL_CAPABILITY_ACK;

        off = dlp->dl_sub_offset;
        len = dlp->dl_sub_length;

        /*
         * Walk the list of capabilities to be enabled.
         */
        for (end = off + len; off < end; ) {
                sp = (dl_capability_sub_t *)(mp->b_rptr + off);
                size = sizeof (dl_capability_sub_t) + sp->dl_length;

                if (off + size > end ||
                    !IS_P2ALIGNED(off, sizeof (uint32_t))) {
                        dl_err = DL_BADPRIM;
                        goto failed;
                }

                switch (sp->dl_cap) {
                /*
                 * TCP/IP checksum offload to hardware.
                 */
                case DL_CAPAB_HCKSUM: {
                        dl_capab_hcksum_t *hcksump;
                        dl_capab_hcksum_t hcksum;

                        hcksump = (dl_capab_hcksum_t *)&sp[1];
                        /*
                         * Copy for alignment.
                         */
                        bcopy(hcksump, &hcksum, sizeof (dl_capab_hcksum_t));
                        dlcapabsetqid(&(hcksum.hcksum_mid), sup->su_rq);
                        bcopy(&hcksum, hcksump, sizeof (dl_capab_hcksum_t));
                        break;
                }

                default:
                        break;
                }

                off += size;
        }
        qreply(q, mp);
        return;
failed:
        dlerrorack(q, mp, DL_CAPABILITY_REQ, dl_err, 0);
}

static void
softmac_bind_req(softmac_upper_t *sup, mblk_t *mp)
{
        softmac_lower_t *slp = sup->su_slp;
        softmac_t       *softmac = sup->su_softmac;
        mblk_t          *ackmp, *mp1;
        int             err;

        if (MBLKL(mp) < DL_BIND_REQ_SIZE) {
                freemsg(mp);
                return;
        }

        /*
         * Allocate ackmp incase the underlying driver does not ack timely.
         */
        if ((mp1 = allocb(sizeof (dl_error_ack_t), BPRI_HI)) == NULL) {
                dlerrorack(sup->su_wq, mp, DL_BIND_REQ, DL_SYSERR, ENOMEM);
                return;
        }

        err = softmac_output(slp, mp, DL_BIND_REQ, DL_BIND_ACK, &ackmp);
        if (ackmp != NULL) {
                freemsg(mp1);
        } else {
                /*
                 * The driver does not ack timely.
                 */
                ASSERT(err == ENOMSG);
                ackmp = mp1;
        }
        if (err != 0)
                goto failed;

        /*
         * Enable capabilities the underlying driver claims to support.
         */
        if ((err = softmac_capab_enable(slp)) != 0)
                goto failed;

        /*
         * Check whether this softmac is already marked as exclusively used,
         * e.g., an aggregation is created over it. Fail the BIND_REQ if so.
         */
        mutex_enter(&softmac->smac_active_mutex);
        if (softmac->smac_active) {
                mutex_exit(&softmac->smac_active_mutex);
                err = EBUSY;
                goto failed;
        }
        softmac->smac_nactive++;
        sup->su_active = B_TRUE;
        mutex_exit(&softmac->smac_active_mutex);
        sup->su_bound = B_TRUE;

        qreply(sup->su_wq, ackmp);
        return;
failed:
        if (err != 0) {
                dlerrorack(sup->su_wq, ackmp, DL_BIND_REQ, DL_SYSERR, err);
                return;
        }
}

static void
softmac_unbind_req(softmac_upper_t *sup, mblk_t *mp)
{
        softmac_lower_t *slp = sup->su_slp;
        softmac_t       *softmac = sup->su_softmac;
        mblk_t          *ackmp, *mp1;
        int             err;

        if (MBLKL(mp) < DL_UNBIND_REQ_SIZE) {
                freemsg(mp);
                return;
        }

        if (!sup->su_bound) {
                dlerrorack(sup->su_wq, mp, DL_UNBIND_REQ, DL_OUTSTATE, 0);
                return;
        }

        /*
         * Allocate ackmp incase the underlying driver does not ack timely.
         */
        if ((mp1 = allocb(sizeof (dl_error_ack_t), BPRI_HI)) == NULL) {
                dlerrorack(sup->su_wq, mp, DL_UNBIND_REQ, DL_SYSERR, ENOMEM);
                return;
        }

        err = softmac_output(slp, mp, DL_UNBIND_REQ, DL_OK_ACK, &ackmp);
        if (ackmp != NULL) {
                freemsg(mp1);
        } else {
                /*
                 * The driver does not ack timely.
                 */
                ASSERT(err == ENOMSG);
                ackmp = mp1;
        }
        if (err != 0) {
                dlerrorack(sup->su_wq, ackmp, DL_UNBIND_REQ, DL_SYSERR, err);
                return;
        }

        sup->su_bound = B_FALSE;

        mutex_enter(&softmac->smac_active_mutex);
        if (sup->su_active) {
                ASSERT(!softmac->smac_active);
                softmac->smac_nactive--;
                sup->su_active = B_FALSE;
        }
        mutex_exit(&softmac->smac_active_mutex);

        qreply(sup->su_wq, ackmp);
}

/*
 * Process the non-data mblk.
 */
static void
softmac_wput_single_nondata(softmac_upper_t *sup, mblk_t *mp)
{
        softmac_t *softmac = sup->su_softmac;
        softmac_lower_t *slp = sup->su_slp;
        unsigned char   dbtype;
        t_uscalar_t     prim;

        dbtype = DB_TYPE(mp);
        sup->su_is_arp = 0;
        switch (dbtype) {
        case M_CTL:
                sup->su_is_arp = 1;
                /* FALLTHROUGH */
        case M_IOCTL: {
                uint32_t        expected_mode;

                if (((struct iocblk *)(mp->b_rptr))->ioc_cmd != SIOCSLIFNAME)
                        break;

                /*
                 * Nak the M_IOCTL based on the STREAMS specification.
                 */
                if (dbtype == M_IOCTL)
                        miocnak(sup->su_wq, mp, 0, EINVAL);
                else
                        freemsg(mp);

                /*
                 * This stream is either IP or ARP. See whether
                 * we need to setup a dedicated-lower-stream for it.
                 */
                mutex_enter(&softmac->smac_fp_mutex);

                expected_mode = DATAPATH_MODE(softmac);
                if (expected_mode == SOFTMAC_SLOWPATH)
                        sup->su_mode = SOFTMAC_SLOWPATH;
                list_insert_head(&softmac->smac_sup_list, sup);
                mutex_exit(&softmac->smac_fp_mutex);

                /*
                 * Setup the fast-path dedicated lower stream if fast-path
                 * is expected. Note that no lock is held here, and if
                 * smac_expected_mode is changed from SOFTMAC_FASTPATH to
                 * SOFTMAC_SLOWPATH, the DL_NOTE_REPLUMB message used for
                 * data-path switching would already be queued and will
                 * be processed by softmac_wput_single_nondata() later.
                 */
                if (expected_mode == SOFTMAC_FASTPATH)
                        (void) softmac_fastpath_setup(sup);
                return;
        }
        case M_PROTO:
        case M_PCPROTO:
                if (MBLKL(mp) < sizeof (t_uscalar_t)) {
                        freemsg(mp);
                        return;
                }
                prim = ((union DL_primitives *)mp->b_rptr)->dl_primitive;
                switch (prim) {
                case DL_NOTIFY_IND:
                        if (MBLKL(mp) < sizeof (dl_notify_ind_t) ||
                            ((dl_notify_ind_t *)mp->b_rptr)->dl_notification !=
                            DL_NOTE_REPLUMB) {
                                freemsg(mp);
                                return;
                        }
                        /*
                         * This DL_NOTE_REPLUMB message is initiated
                         * and queued by the softmac itself, when the
                         * sup is trying to switching its datapath mode
                         * between SOFTMAC_SLOWPATH and SOFTMAC_FASTPATH.
                         * Send this message upstream.
                         */
                        qreply(sup->su_wq, mp);
                        return;
                case DL_NOTIFY_CONF:
                        if (MBLKL(mp) < sizeof (dl_notify_conf_t) ||
                            ((dl_notify_conf_t *)mp->b_rptr)->dl_notification !=
                            DL_NOTE_REPLUMB_DONE) {
                                freemsg(mp);
                                return;
                        }
                        /*
                         * This is an indication from IP/ARP that the
                         * fastpath->slowpath switch is done.
                         */
                        freemsg(mp);
                        softmac_datapath_switch_done(sup);
                        return;
                }
                break;
        }

        /*
         * No need to hold lock to check su_mode, since su_mode updating only
         * operation is is serialized by softmac_wput_nondata_task().
         */
        if (sup->su_mode != SOFTMAC_FASTPATH) {
                (void) dld_wput(sup->su_wq, mp);
                return;
        }

        /*
         * Fastpath non-data message processing. Most of non-data messages
         * can be directly passed down to the dedicated-lower-stream, aside
         * from the following M_PROTO/M_PCPROTO messages.
         */
        switch (dbtype) {
        case M_PROTO:
        case M_PCPROTO:
                switch (prim) {
                case DL_BIND_REQ:
                        softmac_bind_req(sup, mp);
                        break;
                case DL_UNBIND_REQ:
                        softmac_unbind_req(sup, mp);
                        break;
                case DL_CAPABILITY_REQ:
                        softmac_capability_req(sup, mp);
                        break;
                default:
                        putnext(slp->sl_wq, mp);
                        break;
                }
                break;
        default:
                putnext(slp->sl_wq, mp);
                break;
        }
}

/*
 * The worker thread which processes non-data messages. Note we only process
 * one message at one time in order to be able to "flush" the queued message
 * and serialize the processing.
 */
static void
softmac_wput_nondata_task(void *arg)
{
        softmac_upper_t *sup = arg;
        mblk_t          *mp;

        mutex_enter(&sup->su_disp_mutex);

        while (sup->su_pending_head != NULL) {
                if (sup->su_closing)
                        break;

                SOFTMAC_DQ_PENDING(sup, &mp);
                mutex_exit(&sup->su_disp_mutex);
                softmac_wput_single_nondata(sup, mp);
                mutex_enter(&sup->su_disp_mutex);
        }

        /*
         * If the stream is closing, flush all queued messages and inform
         * the stream to be closed.
         */
        freemsgchain(sup->su_pending_head);
        sup->su_pending_head = sup->su_pending_tail = NULL;
        sup->su_dlpi_pending = B_FALSE;
        cv_signal(&sup->su_disp_cv);
        mutex_exit(&sup->su_disp_mutex);
}

/*
 * Kernel thread to handle taskq dispatch failures in softmac_wput_nondata().
 * This thread is started when the softmac module is first loaded.
 */
static void
softmac_taskq_dispatch(void)
{
        callb_cpr_t     cprinfo;
        softmac_upper_t *sup;

        CALLB_CPR_INIT(&cprinfo, &softmac_taskq_lock, callb_generic_cpr,
            "softmac_taskq_dispatch");
        mutex_enter(&softmac_taskq_lock);

        while (!softmac_taskq_quit) {
                sup = list_head(&softmac_taskq_list);
                while (sup != NULL) {
                        list_remove(&softmac_taskq_list, sup);
                        sup->su_taskq_scheduled = B_FALSE;
                        mutex_exit(&softmac_taskq_lock);
                        VERIFY(taskq_dispatch(system_taskq,
                            softmac_wput_nondata_task, sup, TQ_SLEEP) !=
                            TASKQID_INVALID);
                        mutex_enter(&softmac_taskq_lock);
                        sup = list_head(&softmac_taskq_list);
                }

                CALLB_CPR_SAFE_BEGIN(&cprinfo);
                cv_wait(&softmac_taskq_cv, &softmac_taskq_lock);
                CALLB_CPR_SAFE_END(&cprinfo, &softmac_taskq_lock);
        }

        softmac_taskq_done = B_TRUE;
        cv_signal(&softmac_taskq_cv);
        CALLB_CPR_EXIT(&cprinfo);
        thread_exit();
}

void
softmac_wput_nondata(softmac_upper_t *sup, mblk_t *mp)
{
        /*
         * The processing of the message might block. Enqueue the
         * message for later processing.
         */
        mutex_enter(&sup->su_disp_mutex);

        if (sup->su_closing) {
                mutex_exit(&sup->su_disp_mutex);
                freemsg(mp);
                return;
        }

        SOFTMAC_EQ_PENDING(sup, mp);

        if (sup->su_dlpi_pending) {
                mutex_exit(&sup->su_disp_mutex);
                return;
        }
        sup->su_dlpi_pending = B_TRUE;
        mutex_exit(&sup->su_disp_mutex);

        if (taskq_dispatch(system_taskq, softmac_wput_nondata_task,
            sup, TQ_NOSLEEP) != TASKQID_INVALID) {
                return;
        }

        mutex_enter(&softmac_taskq_lock);
        if (!sup->su_taskq_scheduled) {
                list_insert_tail(&softmac_taskq_list, sup);
                cv_signal(&softmac_taskq_cv);
        }
        sup->su_taskq_scheduled = B_TRUE;
        mutex_exit(&softmac_taskq_lock);
}

/*
 * Setup the dedicated-lower-stream (fast-path) for the IP/ARP upperstream.
 */
static int
softmac_fastpath_setup(softmac_upper_t *sup)
{
        softmac_t       *softmac = sup->su_softmac;
        softmac_lower_t *slp;
        int             err;

        err = softmac_lower_setup(softmac, sup, &slp);

        mutex_enter(&sup->su_mutex);
        /*
         * Wait for all data messages to be processed so that we can change
         * the su_mode.
         */
        while (sup->su_tx_inprocess != 0)
                cv_wait(&sup->su_cv, &sup->su_mutex);

        ASSERT(sup->su_mode != SOFTMAC_FASTPATH);
        ASSERT(sup->su_slp == NULL);
        if (err != 0) {
                sup->su_mode = SOFTMAC_SLOWPATH;
        } else {
                sup->su_slp = slp;
                sup->su_mode = SOFTMAC_FASTPATH;
        }
        mutex_exit(&sup->su_mutex);
        return (err);
}

/*
 * Tear down the dedicated-lower-stream (fast-path) for the IP/ARP upperstream.
 */
static void
softmac_fastpath_tear(softmac_upper_t *sup)
{
        mutex_enter(&sup->su_mutex);
        /*
         * Wait for all data messages in the dedicated-lower-stream
         * to be processed.
         */
        while (sup->su_tx_inprocess != 0)
                cv_wait(&sup->su_cv, &sup->su_mutex);

        /*
         * Note that this function is called either when the stream is closed,
         * or the stream is unbound (fastpath-slowpath-switch). Therefore,
         * No need to call the tx_notify callback.
         */
        sup->su_tx_notify_func = NULL;
        sup->su_tx_notify_arg = NULL;
        if (sup->su_tx_busy) {
                ASSERT(sup->su_tx_flow_mp == NULL);
                VERIFY((sup->su_tx_flow_mp = getq(sup->su_wq)) != NULL);
                sup->su_tx_busy = B_FALSE;
        }

        sup->su_mode = SOFTMAC_SLOWPATH;

        /*
         * Destroy the dedicated-lower-stream. Note that slp is destroyed
         * when lh is closed.
         */
        (void) ldi_close(sup->su_slp->sl_lh, FREAD|FWRITE, kcred);
        sup->su_slp = NULL;
        mutex_exit(&sup->su_mutex);
}

void
softmac_wput_data(softmac_upper_t *sup, mblk_t *mp)
{
        /*
         * No lock is required to access the su_mode field since the data
         * traffic is quiesce by IP when the data-path mode is in the
         * process of switching.
         */
        if (sup->su_mode != SOFTMAC_FASTPATH)
                (void) dld_wput(sup->su_wq, mp);
        else
                (void) softmac_fastpath_wput_data(sup, mp, (uintptr_t)NULL, 0);
}

/*ARGSUSED*/
static mac_tx_cookie_t
softmac_fastpath_wput_data(softmac_upper_t *sup, mblk_t *mp, uintptr_t f_hint,
    uint16_t flag)
{
        queue_t         *wq = sup->su_slp->sl_wq;

        /*
         * This function is called from IP, only the MAC_DROP_ON_NO_DESC
         * flag can be specified.
         */
        ASSERT((flag & ~MAC_DROP_ON_NO_DESC) == 0);
        ASSERT(mp->b_next == NULL);

        /*
         * Check wether the dedicated-lower-stream is able to handle more
         * messages, and enable the flow-control if it is not.
         *
         * Note that in order not to introduce any packet reordering, we
         * always send the message down to the dedicated-lower-stream:
         *
         * If the flow-control is already enabled, but we still get
         * the messages from the upper-stream, it means that the upper
         * stream does not respect STREAMS flow-control (e.g., TCP). Simply
         * pass the message down to the lower-stream in that case.
         */
        if (SOFTMAC_CANPUTNEXT(wq)) {
                putnext(wq, mp);
                return ((mac_tx_cookie_t)NULL);
        }

        if (sup->su_tx_busy) {
                if ((flag & MAC_DROP_ON_NO_DESC) != 0)
                        freemsg(mp);
                else
                        putnext(wq, mp);
                return ((mac_tx_cookie_t)sup);
        }

        mutex_enter(&sup->su_mutex);
        if (!sup->su_tx_busy) {
                /*
                 * If DLD_CAPAB_DIRECT is enabled, the notify callback will be
                 * called when the flow control can be disabled. Otherwise,
                 * put the tx_flow_mp into the wq to make use of the old
                 * streams flow control.
                 */
                ASSERT(sup->su_tx_flow_mp != NULL);
                (void) putq(sup->su_wq, sup->su_tx_flow_mp);
                sup->su_tx_flow_mp = NULL;
                sup->su_tx_busy = B_TRUE;
                qenable(wq);
        }
        mutex_exit(&sup->su_mutex);

        if ((flag & MAC_DROP_ON_NO_DESC) != 0)
                freemsg(mp);
        else
                putnext(wq, mp);
        return ((mac_tx_cookie_t)sup);
}

boolean_t
softmac_active_set(void *arg)
{
        softmac_t       *softmac = arg;

        mutex_enter(&softmac->smac_active_mutex);
        if (softmac->smac_nactive != 0) {
                mutex_exit(&softmac->smac_active_mutex);
                return (B_FALSE);
        }
        softmac->smac_active = B_TRUE;
        mutex_exit(&softmac->smac_active_mutex);
        return (B_TRUE);
}

void
softmac_active_clear(void *arg)
{
        softmac_t       *softmac = arg;

        mutex_enter(&softmac->smac_active_mutex);
        ASSERT(softmac->smac_active && (softmac->smac_nactive == 0));
        softmac->smac_active = B_FALSE;
        mutex_exit(&softmac->smac_active_mutex);
}

/*
 * Disable/reenable fastpath on given softmac. This request could come from a
 * MAC client or directly from administrators.
 */
int
softmac_datapath_switch(softmac_t *softmac, boolean_t disable, boolean_t admin)
{
        softmac_upper_t         *sup;
        mblk_t                  *head = NULL, *tail = NULL, *mp;
        list_t                  reqlist;
        softmac_switch_req_t    *req;
        uint32_t                current_mode, expected_mode;
        int                     err = 0;

        mutex_enter(&softmac->smac_fp_mutex);

        current_mode = DATAPATH_MODE(softmac);
        if (admin) {
                if (softmac->smac_fastpath_admin_disabled == disable) {
                        mutex_exit(&softmac->smac_fp_mutex);
                        return (0);
                }
                softmac->smac_fastpath_admin_disabled = disable;
        } else if (disable) {
                softmac->smac_fp_disable_clients++;
        } else {
                ASSERT(softmac->smac_fp_disable_clients != 0);
                softmac->smac_fp_disable_clients--;
        }

        expected_mode = DATAPATH_MODE(softmac);
        if (current_mode == expected_mode) {
                mutex_exit(&softmac->smac_fp_mutex);
                return (0);
        }

        /*
         * The expected mode is different from whatever datapath mode
         * this softmac is expected from last request, enqueue the data-path
         * switch request.
         */
        list_create(&reqlist, sizeof (softmac_switch_req_t),
            offsetof(softmac_switch_req_t, ssq_req_list_node));

        /*
         * Allocate all DL_NOTIFY_IND messages and request structures that
         * are required to switch each IP/ARP stream to the expected mode.
         */
        for (sup = list_head(&softmac->smac_sup_list); sup != NULL;
            sup = list_next(&softmac->smac_sup_list, sup)) {
                dl_notify_ind_t *dlip;

                req = kmem_alloc(sizeof (softmac_switch_req_t), KM_NOSLEEP);
                if (req == NULL)
                        break;

                req->ssq_expected_mode = expected_mode;
                if (sup->su_is_arp) {
                        list_insert_tail(&reqlist, req);
                        continue;
                }
                /*
                 * Allocate the DL_NOTE_REPLUMB message.
                 */
                if ((mp = allocb(sizeof (dl_notify_ind_t), BPRI_LO)) == NULL) {
                        kmem_free(req, sizeof (softmac_switch_req_t));
                        break;
                }

                list_insert_tail(&reqlist, req);

                mp->b_wptr = mp->b_rptr + sizeof (dl_notify_ind_t);
                mp->b_datap->db_type = M_PROTO;
                bzero(mp->b_rptr, sizeof (dl_notify_ind_t));
                dlip = (dl_notify_ind_t *)mp->b_rptr;
                dlip->dl_primitive = DL_NOTIFY_IND;
                dlip->dl_notification = DL_NOTE_REPLUMB;
                if (head == NULL) {
                        head = tail = mp;
                } else {
                        tail->b_next = mp;
                        tail = mp;
                }
        }

        /*
         * Note that it is fine if the expected data-path mode is fast-path
         * and some of streams fails to switch. Only return failure if we
         * are expected to switch to the slow-path.
         */
        if (sup != NULL && expected_mode == SOFTMAC_SLOWPATH) {
                err = ENOMEM;
                goto fail;
        }

        /*
         * Start switching for each IP/ARP stream. The switching operation
         * will eventually succeed and there is no need to wait for it
         * to finish.
         */
        for (sup = list_head(&softmac->smac_sup_list); sup != NULL;
            sup = list_next(&softmac->smac_sup_list, sup)) {
                if (!sup->su_is_arp) {
                        mp = head->b_next;
                        head->b_next = NULL;
                        softmac_wput_nondata(sup, head);
                        head = mp;
                }
                /*
                 * Add the switch request to the requests list of the stream.
                 */
                req = list_head(&reqlist);
                ASSERT(req != NULL);
                list_remove(&reqlist, req);
                list_insert_tail(&sup->su_req_list, req);
        }

        mutex_exit(&softmac->smac_fp_mutex);
        ASSERT(list_is_empty(&reqlist));
        list_destroy(&reqlist);
        return (0);
fail:
        if (admin) {
                softmac->smac_fastpath_admin_disabled = !disable;
        } else if (disable) {
                softmac->smac_fp_disable_clients--;
        } else {
                softmac->smac_fp_disable_clients++;
        }

        mutex_exit(&softmac->smac_fp_mutex);
        while ((req = list_head(&reqlist)) != NULL) {
                list_remove(&reqlist, req);
                kmem_free(req, sizeof (softmac_switch_req_t));
        }
        freemsgchain(head);
        list_destroy(&reqlist);
        return (err);
}

int
softmac_fastpath_disable(void *arg)
{
        return (softmac_datapath_switch((softmac_t *)arg, B_TRUE, B_FALSE));
}

void
softmac_fastpath_enable(void *arg)
{
        VERIFY(softmac_datapath_switch((softmac_t *)arg, B_FALSE,
            B_FALSE) == 0);
}

void
softmac_upperstream_close(softmac_upper_t *sup)
{
        softmac_t               *softmac = sup->su_softmac;
        softmac_switch_req_t    *req;

        mutex_enter(&softmac->smac_fp_mutex);

        if (sup->su_mode == SOFTMAC_FASTPATH)
                softmac_fastpath_tear(sup);

        if (sup->su_mode != SOFTMAC_UNKNOWN) {
                list_remove(&softmac->smac_sup_list, sup);
                sup->su_mode = SOFTMAC_UNKNOWN;
        }

        /*
         * Cleanup all the switch requests queueed on this stream.
         */
        while ((req = list_head(&sup->su_req_list)) != NULL) {
                list_remove(&sup->su_req_list, req);
                kmem_free(req, sizeof (softmac_switch_req_t));
        }
        mutex_exit(&softmac->smac_fp_mutex);
}

/*
 * Handle the DL_NOTE_REPLUMB_DONE indication from IP/ARP. Change the upper
 * stream from the fastpath mode to the slowpath mode.
 */
static void
softmac_datapath_switch_done(softmac_upper_t *sup)
{
        softmac_t               *softmac = sup->su_softmac;
        softmac_switch_req_t    *req;
        uint32_t                expected_mode;

        mutex_enter(&softmac->smac_fp_mutex);
        req = list_head(&sup->su_req_list);
        list_remove(&sup->su_req_list, req);
        expected_mode = req->ssq_expected_mode;
        kmem_free(req, sizeof (softmac_switch_req_t));

        if (expected_mode == sup->su_mode) {
                mutex_exit(&softmac->smac_fp_mutex);
                return;
        }

        ASSERT(!sup->su_bound);
        mutex_exit(&softmac->smac_fp_mutex);

        /*
         * It is fine if the expected mode is fast-path and we fail
         * to enable fastpath on this stream.
         */
        if (expected_mode == SOFTMAC_SLOWPATH)
                softmac_fastpath_tear(sup);
        else
                (void) softmac_fastpath_setup(sup);
}