/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 The FreeBSD Foundation
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/param.h>
#include <sys/bio.h>
#include <sys/condvar.h>
#include <sys/conf.h>
#include <sys/endian.h>
#include <sys/eventhandler.h>
#include <sys/file.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/module.h>
#include <sys/proc.h>
#include <sys/reboot.h>
#include <sys/socket.h>
#include <sys/sockopt.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/sx.h>

#include <vm/uma.h>

#include <cam/cam.h>
#include <cam/cam_ccb.h>
#include <cam/cam_xpt.h>
#include <cam/cam_debug.h>
#include <cam/cam_sim.h>
#include <cam/cam_xpt_sim.h>
#include <cam/cam_xpt_periph.h>
#include <cam/cam_periph.h>
#include <cam/scsi/scsi_all.h>
#include <cam/scsi/scsi_message.h>

#include <dev/iscsi/icl.h>
#include <dev/iscsi/icl_wrappers.h>
#include <dev/iscsi/iscsi_ioctl.h>
#include <dev/iscsi/iscsi_proto.h>
#include <dev/iscsi/iscsi.h>

#ifdef ICL_KERNEL_PROXY
#include <sys/socketvar.h>
#endif

#ifdef ICL_KERNEL_PROXY
FEATURE(iscsi_kernel_proxy, "iSCSI initiator built with ICL_KERNEL_PROXY");
#endif

#ifdef COMPAT_FREEBSD13
struct iscsi_daemon_request13 {
        unsigned int                    idr_session_id;
        struct iscsi_session_conf       idr_conf;
        uint8_t                         idr_isid[6];
        uint16_t                        idr_tsih;
        uint16_t                        idr_spare_cid;
        struct iscsi_session_limits     idr_limits;
        int                             idr_spare[4];
};

#define ISCSIDWAIT13    _IOR('I', 0x01, struct iscsi_daemon_request13)
#endif

/*
 * XXX: This is global so the iscsi_unload() can access it.
 *      Think about how to do this properly.
 */
static struct iscsi_softc       *sc;

SYSCTL_NODE(_kern, OID_AUTO, iscsi, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "iSCSI initiator");
static int debug = 1;
SYSCTL_INT(_kern_iscsi, OID_AUTO, debug, CTLFLAG_RWTUN,
    &debug, 0, "Enable debug messages");

static int ping_timeout = 5;
SYSCTL_INT(_kern_iscsi, OID_AUTO, ping_timeout, CTLFLAG_RWTUN, &ping_timeout,
    0, "Timeout for ping (NOP-Out) requests, in seconds");
static int iscsid_timeout = 60;
SYSCTL_INT(_kern_iscsi, OID_AUTO, iscsid_timeout, CTLFLAG_RWTUN, &iscsid_timeout,
    0, "Time to wait for iscsid(8) to handle reconnection, in seconds");
static int login_timeout = 60;
SYSCTL_INT(_kern_iscsi, OID_AUTO, login_timeout, CTLFLAG_RWTUN, &login_timeout,
    0, "Time to wait for iscsid(8) to finish Login Phase, in seconds");
static int maxtags = 255;
SYSCTL_INT(_kern_iscsi, OID_AUTO, maxtags, CTLFLAG_RWTUN, &maxtags,
    0, "Max number of IO requests queued");
static int fail_on_disconnection = 0;
SYSCTL_INT(_kern_iscsi, OID_AUTO, fail_on_disconnection, CTLFLAG_RWTUN,
    &fail_on_disconnection, 0, "Destroy CAM SIM on connection failure");
static int fail_on_shutdown = 1;
SYSCTL_INT(_kern_iscsi, OID_AUTO, fail_on_shutdown, CTLFLAG_RWTUN,
    &fail_on_shutdown, 0, "Fail disconnected sessions on shutdown");

static MALLOC_DEFINE(M_ISCSI, "iSCSI", "iSCSI initiator");
static uma_zone_t iscsi_outstanding_zone;

#define CONN_SESSION(X) ((struct iscsi_session *)X->ic_prv0)
#define PDU_SESSION(X)  (CONN_SESSION(X->ip_conn))

#define ISCSI_DEBUG(X, ...)                                             \
        do {                                                            \
                if (debug > 1)                                          \
                        printf("%s: " X "\n", __func__, ## __VA_ARGS__);\
        } while (0)

#define ISCSI_WARN(X, ...)                                              \
        do {                                                            \
                if (debug > 0) {                                        \
                        printf("WARNING: %s: " X "\n",                  \
                            __func__, ## __VA_ARGS__);                  \
                }                                                       \
        } while (0)

#define ISCSI_SESSION_DEBUG(S, X, ...)                                  \
        do {                                                            \
                if (debug > 1) {                                        \
                        printf("%s: %s (%s): " X "\n",                  \
                            __func__, S->is_conf.isc_target_addr,       \
                            S->is_conf.isc_target, ## __VA_ARGS__);     \
                }                                                       \
        } while (0)

#define ISCSI_SESSION_WARN(S, X, ...)                                   \
        do {                                                            \
                if (debug > 0) {                                        \
                        printf("WARNING: %s (%s): " X "\n",             \
                            S->is_conf.isc_target_addr,                 \
                            S->is_conf.isc_target, ## __VA_ARGS__);     \
                }                                                       \
        } while (0)

#define ISCSI_SESSION_LOCK(X)           mtx_lock(&X->is_lock)
#define ISCSI_SESSION_UNLOCK(X)         mtx_unlock(&X->is_lock)
#define ISCSI_SESSION_LOCK_ASSERT(X)    mtx_assert(&X->is_lock, MA_OWNED)
#define ISCSI_SESSION_LOCK_ASSERT_NOT(X) mtx_assert(&X->is_lock, MA_NOTOWNED)

static int      iscsi_ioctl(struct cdev *dev, u_long cmd, caddr_t arg,
                    int mode, struct thread *td);

static struct cdevsw iscsi_cdevsw = {
     .d_version = D_VERSION,
     .d_ioctl   = iscsi_ioctl,
     .d_name    = "iscsi",
};

static void     iscsi_pdu_queue_locked(struct icl_pdu *request);
static void     iscsi_pdu_queue(struct icl_pdu *request);
static void     iscsi_pdu_update_statsn(const struct icl_pdu *response);
static void     iscsi_pdu_handle_nop_in(struct icl_pdu *response);
static void     iscsi_pdu_handle_scsi_response(struct icl_pdu *response);
static void     iscsi_pdu_handle_task_response(struct icl_pdu *response);
static void     iscsi_pdu_handle_data_in(struct icl_pdu *response);
static void     iscsi_pdu_handle_logout_response(struct icl_pdu *response);
static void     iscsi_pdu_handle_r2t(struct icl_pdu *response);
static void     iscsi_pdu_handle_async_message(struct icl_pdu *response);
static void     iscsi_pdu_handle_reject(struct icl_pdu *response);
static void     iscsi_session_reconnect(struct iscsi_session *is);
static void     iscsi_session_terminate(struct iscsi_session *is);
static void     iscsi_action(struct cam_sim *sim, union ccb *ccb);
static struct iscsi_outstanding *iscsi_outstanding_find(struct iscsi_session *is,
                    uint32_t initiator_task_tag);
static struct iscsi_outstanding *iscsi_outstanding_add(struct iscsi_session *is,
                    struct icl_pdu *request, union ccb *ccb,
                    uint32_t *initiator_task_tagp);
static void     iscsi_outstanding_remove(struct iscsi_session *is,
                    struct iscsi_outstanding *io);

static bool
iscsi_pdu_prepare(struct icl_pdu *request)
{
        struct iscsi_session *is;
        struct iscsi_bhs_scsi_command *bhssc;

        is = PDU_SESSION(request);

        ISCSI_SESSION_LOCK_ASSERT(is);

        /*
         * We're only using fields common for all the request
         * (initiator -> target) PDUs.
         */
        bhssc = (struct iscsi_bhs_scsi_command *)request->ip_bhs;

        /*
         * Data-Out PDU does not contain CmdSN.
         */
        if (bhssc->bhssc_opcode != ISCSI_BHS_OPCODE_SCSI_DATA_OUT) {
                if (ISCSI_SNGT(is->is_cmdsn, is->is_maxcmdsn) &&
                    (bhssc->bhssc_opcode & ISCSI_BHS_OPCODE_IMMEDIATE) == 0) {
                        /*
                         * Current MaxCmdSN prevents us from sending any more
                         * SCSI Command PDUs to the target; postpone the PDU.
                         * It will get resent by either iscsi_pdu_queue(),
                         * or by maintenance thread.
                         */
#if 0
                        ISCSI_SESSION_DEBUG(is, "postponing send, CmdSN %u, "
                            "ExpCmdSN %u, MaxCmdSN %u, opcode 0x%x",
                            is->is_cmdsn, is->is_expcmdsn, is->is_maxcmdsn,
                            bhssc->bhssc_opcode);
#endif
                        return (true);
                }
                bhssc->bhssc_cmdsn = htonl(is->is_cmdsn);
                if ((bhssc->bhssc_opcode & ISCSI_BHS_OPCODE_IMMEDIATE) == 0)
                        is->is_cmdsn++;
        }
        bhssc->bhssc_expstatsn = htonl(is->is_statsn + 1);

        return (false);
}

static void
iscsi_session_send_postponed(struct iscsi_session *is)
{
        struct icl_pdu *request;
        bool postpone;

        ISCSI_SESSION_LOCK_ASSERT(is);

        if (STAILQ_EMPTY(&is->is_postponed))
                return;
        while ((request = STAILQ_FIRST(&is->is_postponed)) != NULL) {
                postpone = iscsi_pdu_prepare(request);
                if (postpone)
                        return;
                STAILQ_REMOVE_HEAD(&is->is_postponed, ip_next);
                icl_pdu_queue(request);
        }
        xpt_release_simq(is->is_sim, 1);
}

static void
iscsi_pdu_queue_locked(struct icl_pdu *request)
{
        struct iscsi_session *is;
        bool postpone;

        is = PDU_SESSION(request);
        ISCSI_SESSION_LOCK_ASSERT(is);
        iscsi_session_send_postponed(is);
        postpone = iscsi_pdu_prepare(request);
        if (postpone) {
                if (STAILQ_EMPTY(&is->is_postponed))
                        xpt_freeze_simq(is->is_sim, 1);
                STAILQ_INSERT_TAIL(&is->is_postponed, request, ip_next);
                return;
        }
        icl_pdu_queue(request);
}

static void
iscsi_pdu_queue(struct icl_pdu *request)
{
        struct iscsi_session *is;

        is = PDU_SESSION(request);
        ISCSI_SESSION_LOCK(is);
        iscsi_pdu_queue_locked(request);
        ISCSI_SESSION_UNLOCK(is);
}

static void
iscsi_session_logout(struct iscsi_session *is)
{
        struct icl_pdu *request;
        struct iscsi_bhs_logout_request *bhslr;

        request = icl_pdu_new(is->is_conn, M_NOWAIT);
        if (request == NULL)
                return;

        bhslr = (struct iscsi_bhs_logout_request *)request->ip_bhs;
        bhslr->bhslr_opcode = ISCSI_BHS_OPCODE_LOGOUT_REQUEST;
        bhslr->bhslr_reason = BHSLR_REASON_CLOSE_SESSION;
        iscsi_pdu_queue_locked(request);
}

static void
iscsi_session_terminate_task(struct iscsi_session *is,
    struct iscsi_outstanding *io, cam_status status)
{

        ISCSI_SESSION_LOCK_ASSERT(is);

        if (io->io_ccb != NULL) {
                io->io_ccb->ccb_h.status &= ~(CAM_SIM_QUEUED | CAM_STATUS_MASK);
                io->io_ccb->ccb_h.status |= status;
                if ((io->io_ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                        io->io_ccb->ccb_h.status |= CAM_DEV_QFRZN;
                        xpt_freeze_devq(io->io_ccb->ccb_h.path, 1);
                        ISCSI_SESSION_DEBUG(is, "freezing devq");
                }
                xpt_done(io->io_ccb);
        }
        iscsi_outstanding_remove(is, io);
}

static void
iscsi_session_terminate_tasks(struct iscsi_session *is, cam_status status)
{
        struct iscsi_outstanding *io, *tmp;

        ISCSI_SESSION_LOCK_ASSERT(is);

        TAILQ_FOREACH_SAFE(io, &is->is_outstanding, io_next, tmp) {
                iscsi_session_terminate_task(is, io, status);
        }
}

static void
iscsi_session_cleanup(struct iscsi_session *is, bool destroy_sim)
{
        struct icl_pdu *pdu;

        ISCSI_SESSION_LOCK_ASSERT(is);

        /*
         * Don't queue any new PDUs.
         */
        if (is->is_sim != NULL && is->is_simq_frozen == false) {
                ISCSI_SESSION_DEBUG(is, "freezing");
                xpt_freeze_simq(is->is_sim, 1);
                is->is_simq_frozen = true;
        }

        /*
         * Remove postponed PDUs.
         */
        if (!STAILQ_EMPTY(&is->is_postponed))
                xpt_release_simq(is->is_sim, 1);
        while ((pdu = STAILQ_FIRST(&is->is_postponed)) != NULL) {
                STAILQ_REMOVE_HEAD(&is->is_postponed, ip_next);
                icl_pdu_free(pdu);
        }

        if (destroy_sim == false) {
                /*
                 * Terminate SCSI tasks, asking CAM to requeue them.
                 */
                iscsi_session_terminate_tasks(is, CAM_REQUEUE_REQ);
                return;
        }

        iscsi_session_terminate_tasks(is, CAM_DEV_NOT_THERE);

        if (is->is_sim == NULL)
                return;

        ISCSI_SESSION_DEBUG(is, "deregistering SIM");
        xpt_async(AC_LOST_DEVICE, is->is_path, NULL);

        if (is->is_simq_frozen) {
                is->is_simq_frozen = false;
                xpt_release_simq(is->is_sim, 1);
        }

        xpt_free_path(is->is_path);
        is->is_path = NULL;
        xpt_bus_deregister(cam_sim_path(is->is_sim));
        cam_sim_free(is->is_sim, TRUE /*free_devq*/);
        is->is_sim = NULL;
        is->is_devq = NULL;
}

static void
iscsi_maintenance_thread_reconnect(struct iscsi_session *is)
{
        /*
         * As we will be reconnecting shortly,
         * discard outstanding data immediately on
         * close(), also notify peer via RST if
         * any packets come in.
         */
        struct socket *so;
        so = is->is_conn->ic_socket;
        if (so != NULL) {
                struct sockopt sopt;
                struct linger sl;
                sopt.sopt_dir     = SOPT_SET;
                sopt.sopt_level   = SOL_SOCKET;
                sopt.sopt_name    = SO_LINGER;
                sopt.sopt_val     = &sl;
                sopt.sopt_valsize = sizeof(sl);
                sl.l_onoff        = 1;  /* non-zero value enables linger option in kernel */
                sl.l_linger       = 0;  /* timeout interval in seconds */
                sosetopt(is->is_conn->ic_socket, &sopt);
        }

        icl_conn_close(is->is_conn);

        ISCSI_SESSION_LOCK(is);

        is->is_connected = false;
        is->is_reconnecting = false;
        is->is_login_phase = false;

#ifdef ICL_KERNEL_PROXY
        if (is->is_login_pdu != NULL) {
                icl_pdu_free(is->is_login_pdu);
                is->is_login_pdu = NULL;
        }
        cv_signal(&is->is_login_cv);
#endif

        if (fail_on_disconnection) {
                ISCSI_SESSION_DEBUG(is, "connection failed, destroying devices");
                iscsi_session_cleanup(is, true);
        } else {
                iscsi_session_cleanup(is, false);
        }

        KASSERT(TAILQ_EMPTY(&is->is_outstanding),
            ("destroying session with active tasks"));
        KASSERT(STAILQ_EMPTY(&is->is_postponed),
            ("destroying session with postponed PDUs"));

        if (is->is_conf.isc_enable == 0 && is->is_conf.isc_discovery == 0) {
                ISCSI_SESSION_UNLOCK(is);
                return;
        }

        /*
         * Request immediate reconnection from iscsid(8).
         */
        //ISCSI_SESSION_DEBUG(is, "waking up iscsid(8)");
        is->is_waiting_for_iscsid = true;
        strlcpy(is->is_reason, "Waiting for iscsid(8)", sizeof(is->is_reason));
        is->is_timeout = 0;
        ISCSI_SESSION_UNLOCK(is);
        cv_signal(&is->is_softc->sc_cv);
}

static void
iscsi_maintenance_thread_terminate(struct iscsi_session *is)
{
        struct iscsi_softc *sc;

        sc = is->is_softc;
        sx_xlock(&sc->sc_lock);
        TAILQ_REMOVE(&sc->sc_sessions, is, is_next);
        sx_xunlock(&sc->sc_lock);

        icl_conn_close(is->is_conn);
        callout_drain(&is->is_callout);

        ISCSI_SESSION_LOCK(is);

        KASSERT(is->is_terminating, ("is_terminating == false"));

#ifdef ICL_KERNEL_PROXY
        if (is->is_login_pdu != NULL) {
                icl_pdu_free(is->is_login_pdu);
                is->is_login_pdu = NULL;
        }
        cv_signal(&is->is_login_cv);
#endif

        iscsi_session_cleanup(is, true);

        KASSERT(TAILQ_EMPTY(&is->is_outstanding),
            ("destroying session with active tasks"));
        KASSERT(STAILQ_EMPTY(&is->is_postponed),
            ("destroying session with postponed PDUs"));

        ISCSI_SESSION_UNLOCK(is);

        icl_conn_free(is->is_conn);
        mtx_destroy(&is->is_lock);
        cv_destroy(&is->is_maintenance_cv);
#ifdef ICL_KERNEL_PROXY
        cv_destroy(&is->is_login_cv);
#endif

        ISCSI_SESSION_DEBUG(is, "terminated");
        free(is, M_ISCSI);

        /*
         * The iscsi_unload() routine might be waiting.
         */
        cv_signal(&sc->sc_cv);
}

static void
iscsi_maintenance_thread(void *arg)
{
        struct iscsi_session *is = arg;

        ISCSI_SESSION_LOCK(is);
        for (;;) {
                if (is->is_reconnecting == false &&
                    is->is_terminating == false &&
                    (STAILQ_EMPTY(&is->is_postponed) ||
                     ISCSI_SNGT(is->is_cmdsn, is->is_maxcmdsn)))
                        cv_wait(&is->is_maintenance_cv, &is->is_lock);

                /* Terminate supersedes reconnect. */
                if (is->is_terminating) {
                        ISCSI_SESSION_UNLOCK(is);
                        iscsi_maintenance_thread_terminate(is);
                        kthread_exit();
                        return;
                }

                if (is->is_reconnecting) {
                        ISCSI_SESSION_UNLOCK(is);
                        iscsi_maintenance_thread_reconnect(is);
                        ISCSI_SESSION_LOCK(is);
                        continue;
                }

                iscsi_session_send_postponed(is);
        }
        ISCSI_SESSION_UNLOCK(is);
}

static void
iscsi_session_reconnect(struct iscsi_session *is)
{

        /*
         * XXX: We can't use locking here, because
         *      it's being called from various contexts.
         *      Hope it doesn't break anything.
         */
        if (is->is_reconnecting)
                return;

        is->is_reconnecting = true;
        cv_signal(&is->is_maintenance_cv);
}

static void
iscsi_session_terminate(struct iscsi_session *is)
{

        if (is->is_terminating)
                return;

        is->is_terminating = true;

#if 0
        iscsi_session_logout(is);
#endif
        cv_signal(&is->is_maintenance_cv);
}

static void
iscsi_callout(void *context)
{
        struct icl_pdu *request;
        struct iscsi_bhs_nop_out *bhsno;
        struct iscsi_session *is;
        bool reconnect_needed = false;
        sbintime_t sbt, pr;

        is = context;

        ISCSI_SESSION_LOCK(is);
        if (is->is_terminating) {
                ISCSI_SESSION_UNLOCK(is);
                return;
        }

        sbt = mstosbt(995);
        pr  = mstosbt(10);
        callout_schedule_sbt(&is->is_callout, sbt, pr, 0);

        if (is->is_conf.isc_enable == 0)
                goto out;

        is->is_timeout++;

        if (is->is_waiting_for_iscsid) {
                if (iscsid_timeout > 0 && is->is_timeout > iscsid_timeout) {
                        ISCSI_SESSION_WARN(is, "timed out waiting for iscsid(8) "
                            "for %d seconds; reconnecting",
                            is->is_timeout);
                        reconnect_needed = true;
                }
                goto out;
        }

        if (is->is_login_phase) {
                if (is->is_login_timeout > 0 && is->is_timeout > is->is_login_timeout) {
                        ISCSI_SESSION_WARN(is, "login timed out after %d seconds; "
                            "reconnecting", is->is_timeout);
                        reconnect_needed = true;
                }
                goto out;
        }

        if (is->is_ping_timeout <= 0) {
                /*
                 * Pings are disabled.  Don't send NOP-Out in this case.
                 * Reset the timeout, to avoid triggering reconnection,
                 * should the user decide to reenable them.
                 */
                is->is_timeout = 0;
                goto out;
        }

        if (is->is_timeout >= is->is_ping_timeout) {
                ISCSI_SESSION_WARN(is, "no ping reply (NOP-In) after %d seconds; "
                    "reconnecting", is->is_ping_timeout);
                reconnect_needed = true;
                goto out;
        }

        ISCSI_SESSION_UNLOCK(is);

        /*
         * If the ping was reset less than one second ago - which means
         * that we've received some PDU during the last second - assume
         * the traffic flows correctly and don't bother sending a NOP-Out.
         *
         * (It's 2 - one for one second, and one for incrementing is_timeout
         * earlier in this routine.)
         */
        if (is->is_timeout < 2)
                return;

        request = icl_pdu_new(is->is_conn, M_NOWAIT);
        if (request == NULL) {
                ISCSI_SESSION_WARN(is, "failed to allocate PDU");
                return;
        }
        bhsno = (struct iscsi_bhs_nop_out *)request->ip_bhs;
        bhsno->bhsno_opcode = ISCSI_BHS_OPCODE_NOP_OUT |
            ISCSI_BHS_OPCODE_IMMEDIATE;
        bhsno->bhsno_flags = 0x80;
        bhsno->bhsno_target_transfer_tag = 0xffffffff;
        iscsi_pdu_queue(request);
        return;

out:
        if (is->is_terminating) {
                ISCSI_SESSION_UNLOCK(is);
                return;
        }

        ISCSI_SESSION_UNLOCK(is);

        if (reconnect_needed)
                iscsi_session_reconnect(is);
}

static void
iscsi_pdu_update_statsn(const struct icl_pdu *response)
{
        const struct iscsi_bhs_data_in *bhsdi;
        struct iscsi_session *is;
        uint32_t expcmdsn, maxcmdsn, statsn;

        is = PDU_SESSION(response);

        ISCSI_SESSION_LOCK_ASSERT(is);

        /*
         * We're only using fields common for all the response
         * (target -> initiator) PDUs.
         */
        bhsdi = (const struct iscsi_bhs_data_in *)response->ip_bhs;
        /*
         * Ok, I lied.  In case of Data-In, "The fields StatSN, Status,
         * and Residual Count only have meaningful content if the S bit
         * is set to 1", so we also need to check the bit specific for
         * Data-In PDU.
         */
        if (bhsdi->bhsdi_opcode != ISCSI_BHS_OPCODE_SCSI_DATA_IN ||
            (bhsdi->bhsdi_flags & BHSDI_FLAGS_S) != 0) {
                statsn = ntohl(bhsdi->bhsdi_statsn);
                if (statsn != is->is_statsn && statsn != (is->is_statsn + 1)) {
                        /* XXX: This is normal situation for MCS */
                        ISCSI_SESSION_WARN(is, "PDU 0x%x StatSN %u != "
                            "session ExpStatSN %u (or + 1); reconnecting",
                            bhsdi->bhsdi_opcode, statsn, is->is_statsn);
                        iscsi_session_reconnect(is);
                }
                if (ISCSI_SNGT(statsn, is->is_statsn))
                        is->is_statsn = statsn;
        }

        expcmdsn = ntohl(bhsdi->bhsdi_expcmdsn);
        maxcmdsn = ntohl(bhsdi->bhsdi_maxcmdsn);

        if (ISCSI_SNLT(maxcmdsn + 1, expcmdsn)) {
                ISCSI_SESSION_DEBUG(is,
                    "PDU MaxCmdSN %u + 1 < PDU ExpCmdSN %u; ignoring",
                    maxcmdsn, expcmdsn);
        } else {
                if (ISCSI_SNGT(maxcmdsn, is->is_maxcmdsn)) {
                        is->is_maxcmdsn = maxcmdsn;

                        /*
                         * Command window increased; kick the maintanance thread
                         * to send out postponed commands.
                         */
                        if (!STAILQ_EMPTY(&is->is_postponed))
                                cv_signal(&is->is_maintenance_cv);
                } else if (ISCSI_SNLT(maxcmdsn, is->is_maxcmdsn)) {
                        /* XXX: This is normal situation for MCS */
                        ISCSI_SESSION_DEBUG(is,
                            "PDU MaxCmdSN %u < session MaxCmdSN %u; ignoring",
                            maxcmdsn, is->is_maxcmdsn);
                }

                if (ISCSI_SNGT(expcmdsn, is->is_expcmdsn)) {
                        is->is_expcmdsn = expcmdsn;
                } else if (ISCSI_SNLT(expcmdsn, is->is_expcmdsn)) {
                        /* XXX: This is normal situation for MCS */
                        ISCSI_SESSION_DEBUG(is,
                            "PDU ExpCmdSN %u < session ExpCmdSN %u; ignoring",
                            expcmdsn, is->is_expcmdsn);
                }
        }

        /*
         * Every incoming PDU - not just NOP-In - resets the ping timer.
         * The purpose of the timeout is to reset the connection when it stalls;
         * we don't want this to happen when NOP-In or NOP-Out ends up delayed
         * in some queue.
         */
        is->is_timeout = 0;
}

static void
iscsi_receive_callback(struct icl_pdu *response)
{
        struct iscsi_session *is;

        is = PDU_SESSION(response);

        ISCSI_SESSION_LOCK(is);

        iscsi_pdu_update_statsn(response);

#ifdef ICL_KERNEL_PROXY
        if (is->is_login_phase) {
                if (is->is_login_pdu == NULL)
                        is->is_login_pdu = response;
                else
                        icl_pdu_free(response);
                ISCSI_SESSION_UNLOCK(is);
                cv_signal(&is->is_login_cv);
                return;
        }
#endif

        /*
         * The handling routine is responsible for freeing the PDU
         * when it's no longer needed.
         */
        switch (response->ip_bhs->bhs_opcode) {
        case ISCSI_BHS_OPCODE_NOP_IN:
                iscsi_pdu_handle_nop_in(response);
                ISCSI_SESSION_UNLOCK(is);
                break;
        case ISCSI_BHS_OPCODE_SCSI_RESPONSE:
                iscsi_pdu_handle_scsi_response(response);
                /* Session lock dropped inside. */
                ISCSI_SESSION_LOCK_ASSERT_NOT(is);
                break;
        case ISCSI_BHS_OPCODE_TASK_RESPONSE:
                iscsi_pdu_handle_task_response(response);
                ISCSI_SESSION_UNLOCK(is);
                break;
        case ISCSI_BHS_OPCODE_SCSI_DATA_IN:
                iscsi_pdu_handle_data_in(response);
                /* Session lock dropped inside. */
                ISCSI_SESSION_LOCK_ASSERT_NOT(is);
                break;
        case ISCSI_BHS_OPCODE_LOGOUT_RESPONSE:
                iscsi_pdu_handle_logout_response(response);
                ISCSI_SESSION_UNLOCK(is);
                break;
        case ISCSI_BHS_OPCODE_R2T:
                iscsi_pdu_handle_r2t(response);
                ISCSI_SESSION_UNLOCK(is);
                break;
        case ISCSI_BHS_OPCODE_ASYNC_MESSAGE:
                iscsi_pdu_handle_async_message(response);
                ISCSI_SESSION_UNLOCK(is);
                break;
        case ISCSI_BHS_OPCODE_REJECT:
                iscsi_pdu_handle_reject(response);
                ISCSI_SESSION_UNLOCK(is);
                break;
        default:
                ISCSI_SESSION_WARN(is, "received PDU with unsupported "
                    "opcode 0x%x; reconnecting",
                    response->ip_bhs->bhs_opcode);
                iscsi_session_reconnect(is);
                ISCSI_SESSION_UNLOCK(is);
                icl_pdu_free(response);
        }
}

static void
iscsi_error_callback(struct icl_conn *ic)
{
        struct iscsi_session *is;

        is = CONN_SESSION(ic);

        ISCSI_SESSION_WARN(is, "connection error; reconnecting");
        iscsi_session_reconnect(is);
}

static void
iscsi_pdu_handle_nop_in(struct icl_pdu *response)
{
        struct iscsi_session *is;
        struct iscsi_bhs_nop_out *bhsno;
        struct iscsi_bhs_nop_in *bhsni;
        struct icl_pdu *request;
        void *data = NULL;
        size_t datasize;
        int error;

        is = PDU_SESSION(response);
        bhsni = (struct iscsi_bhs_nop_in *)response->ip_bhs;

        if (bhsni->bhsni_target_transfer_tag == 0xffffffff) {
                /*
                 * Nothing to do; iscsi_pdu_update_statsn() already
                 * zeroed the timeout.
                 */
                icl_pdu_free(response);
                return;
        }

        datasize = icl_pdu_data_segment_length(response);
        if (datasize > 0) {
                data = malloc(datasize, M_ISCSI, M_NOWAIT | M_ZERO);
                if (data == NULL) {
                        ISCSI_SESSION_WARN(is, "failed to allocate memory; "
                            "reconnecting");
                        icl_pdu_free(response);
                        iscsi_session_reconnect(is);
                        return;
                }
                icl_pdu_get_data(response, 0, data, datasize);
        }

        request = icl_pdu_new(response->ip_conn, M_NOWAIT);
        if (request == NULL) {
                ISCSI_SESSION_WARN(is, "failed to allocate memory; "
                    "reconnecting");
                free(data, M_ISCSI);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                return;
        }
        bhsno = (struct iscsi_bhs_nop_out *)request->ip_bhs;
        bhsno->bhsno_opcode = ISCSI_BHS_OPCODE_NOP_OUT |
            ISCSI_BHS_OPCODE_IMMEDIATE;
        bhsno->bhsno_flags = 0x80;
        bhsno->bhsno_initiator_task_tag = 0xffffffff;
        bhsno->bhsno_target_transfer_tag = bhsni->bhsni_target_transfer_tag;
        if (datasize > 0) {
                error = icl_pdu_append_data(request, data, datasize, M_NOWAIT);
                if (error != 0) {
                        ISCSI_SESSION_WARN(is, "failed to allocate memory; "
                            "reconnecting");
                        free(data, M_ISCSI);
                        icl_pdu_free(request);
                        icl_pdu_free(response);
                        iscsi_session_reconnect(is);
                        return;
                }
                free(data, M_ISCSI);
        }

        icl_pdu_free(response);
        iscsi_pdu_queue_locked(request);
}

static void
iscsi_pdu_handle_scsi_response(struct icl_pdu *response)
{
        struct iscsi_bhs_scsi_response *bhssr;
        struct iscsi_outstanding *io;
        struct iscsi_session *is;
        union ccb *ccb;
        struct ccb_scsiio *csio;
        size_t data_segment_len, received;
        uint16_t sense_len;
        uint32_t resid;

        is = PDU_SESSION(response);

        bhssr = (struct iscsi_bhs_scsi_response *)response->ip_bhs;
        io = iscsi_outstanding_find(is, bhssr->bhssr_initiator_task_tag);
        if (io == NULL || io->io_ccb == NULL) {
                ISCSI_SESSION_WARN(is, "bad itt 0x%x", bhssr->bhssr_initiator_task_tag);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                ISCSI_SESSION_UNLOCK(is);
                return;
        }

        ccb = io->io_ccb;
        if (bhssr->bhssr_response == BHSSR_RESPONSE_COMMAND_COMPLETED) {
                if (ntohl(bhssr->bhssr_expdatasn) != io->io_datasn) {
                        ISCSI_SESSION_WARN(is,
                            "ExpDataSN mismatch in SCSI Response (%u vs %u)",
                            ntohl(bhssr->bhssr_expdatasn), io->io_datasn);

                        /*
                         * XXX: Permit an ExpDataSN of zero for errors.
                         *
                         * This doesn't conform to RFC 7143, but some
                         * targets seem to do this.
                         */
                        if (bhssr->bhssr_status != 0 &&
                            bhssr->bhssr_expdatasn == htonl(0))
                                goto skip_expdatasn;

                        icl_pdu_free(response);
                        iscsi_session_reconnect(is);
                        ISCSI_SESSION_UNLOCK(is);
                        return;
                }
        } else {
                if (bhssr->bhssr_expdatasn != htonl(0)) {
                        ISCSI_SESSION_WARN(is,
                            "ExpDataSN mismatch in SCSI Response (%u vs 0)",
                            ntohl(bhssr->bhssr_expdatasn));
                        icl_pdu_free(response);
                        iscsi_session_reconnect(is);
                        ISCSI_SESSION_UNLOCK(is);
                        return;
                }
        }
skip_expdatasn:

        /*
         * With iSER, after getting good response we can be sure
         * that all the data has been successfully transferred.
         */
        if (is->is_conn->ic_iser) {
                resid = ntohl(bhssr->bhssr_residual_count);
                if (bhssr->bhssr_flags & BHSSR_FLAGS_RESIDUAL_UNDERFLOW) {
                        io->io_received = ccb->csio.dxfer_len - resid;
                } else if (bhssr->bhssr_flags & BHSSR_FLAGS_RESIDUAL_OVERFLOW) {
                        ISCSI_SESSION_WARN(is, "overflow: target indicates %d", resid);
                } else {
                        io->io_received = ccb->csio.dxfer_len;
                }
        }

        received = io->io_received;
        iscsi_outstanding_remove(is, io);
        ISCSI_SESSION_UNLOCK(is);

        if (bhssr->bhssr_response != BHSSR_RESPONSE_COMMAND_COMPLETED) {
                ISCSI_SESSION_WARN(is, "service response 0x%x", bhssr->bhssr_response);
                if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                        xpt_freeze_devq(ccb->ccb_h.path, 1);
                        ISCSI_SESSION_DEBUG(is, "freezing devq");
                }
                ccb->ccb_h.status = CAM_REQ_CMP_ERR | CAM_DEV_QFRZN;
        } else if (bhssr->bhssr_status == 0) {
                ccb->ccb_h.status = CAM_REQ_CMP;
        } else {
                if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                        xpt_freeze_devq(ccb->ccb_h.path, 1);
                        ISCSI_SESSION_DEBUG(is, "freezing devq");
                }
                ccb->ccb_h.status = CAM_SCSI_STATUS_ERROR | CAM_DEV_QFRZN;
                ccb->csio.scsi_status = bhssr->bhssr_status;
        }

        csio = &ccb->csio;
        data_segment_len = icl_pdu_data_segment_length(response);
        if (data_segment_len > 0) {
                if (data_segment_len < sizeof(sense_len)) {
                        ISCSI_SESSION_WARN(is, "truncated data segment (%zd bytes)",
                            data_segment_len);
                        if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                                xpt_freeze_devq(ccb->ccb_h.path, 1);
                                ISCSI_SESSION_DEBUG(is, "freezing devq");
                        }
                        ccb->ccb_h.status = CAM_REQ_CMP_ERR | CAM_DEV_QFRZN;
                        goto out;
                }
                icl_pdu_get_data(response, 0, &sense_len, sizeof(sense_len));
                sense_len = ntohs(sense_len);
#if 0
                ISCSI_SESSION_DEBUG(is, "sense_len %d, data len %zd",
                    sense_len, data_segment_len);
#endif
                if (sizeof(sense_len) + sense_len > data_segment_len) {
                        ISCSI_SESSION_WARN(is, "truncated data segment "
                            "(%zd bytes, should be %zd)",
                            data_segment_len, sizeof(sense_len) + sense_len);
                        if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                                xpt_freeze_devq(ccb->ccb_h.path, 1);
                                ISCSI_SESSION_DEBUG(is, "freezing devq");
                        }
                        ccb->ccb_h.status = CAM_REQ_CMP_ERR | CAM_DEV_QFRZN;
                        goto out;
                } else if (sizeof(sense_len) + sense_len < data_segment_len)
                        ISCSI_SESSION_WARN(is, "oversize data segment "
                            "(%zd bytes, should be %zd)",
                            data_segment_len, sizeof(sense_len) + sense_len);
                if (sense_len > csio->sense_len) {
                        ISCSI_SESSION_DEBUG(is, "truncating sense from %d to %d",
                            sense_len, csio->sense_len);
                        sense_len = csio->sense_len;
                }
                icl_pdu_get_data(response, sizeof(sense_len), &csio->sense_data, sense_len);
                csio->sense_resid = csio->sense_len - sense_len;
                ccb->ccb_h.status |= CAM_AUTOSNS_VALID;
        }

out:
        if (bhssr->bhssr_flags & BHSSR_FLAGS_RESIDUAL_UNDERFLOW)
                csio->resid = ntohl(bhssr->bhssr_residual_count);

        if ((csio->ccb_h.flags & CAM_DIR_MASK) == CAM_DIR_IN) {
                KASSERT(received <= csio->dxfer_len,
                    ("received > csio->dxfer_len"));
                if (received < csio->dxfer_len) {
                        if (csio->resid != csio->dxfer_len - received) {
                                ISCSI_SESSION_WARN(is, "underflow mismatch: "
                                    "target indicates %d, we calculated %zd",
                                    csio->resid, csio->dxfer_len - received);
                        }
                        csio->resid = csio->dxfer_len - received;
                }
        }

        xpt_done(ccb);
        icl_pdu_free(response);
}

static void
iscsi_pdu_handle_task_response(struct icl_pdu *response)
{
        struct iscsi_bhs_task_management_response *bhstmr;
        struct iscsi_outstanding *io, *aio;
        struct iscsi_session *is;

        is = PDU_SESSION(response);

        bhstmr = (struct iscsi_bhs_task_management_response *)response->ip_bhs;
        io = iscsi_outstanding_find(is, bhstmr->bhstmr_initiator_task_tag);
        if (io == NULL || io->io_ccb != NULL) {
                ISCSI_SESSION_WARN(is, "bad itt 0x%x",
                    bhstmr->bhstmr_initiator_task_tag);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                return;
        }

        if (bhstmr->bhstmr_response != BHSTMR_RESPONSE_FUNCTION_COMPLETE) {
                ISCSI_SESSION_WARN(is, "task response 0x%x",
                    bhstmr->bhstmr_response);
        } else {
                aio = iscsi_outstanding_find(is, io->io_referenced_task_tag);
                if (aio != NULL && aio->io_ccb != NULL)
                        iscsi_session_terminate_task(is, aio, CAM_REQ_ABORTED);
        }

        iscsi_outstanding_remove(is, io);
        icl_pdu_free(response);
}

static void
iscsi_pdu_get_data_csio(struct icl_pdu *response, size_t pdu_offset,
    struct ccb_scsiio *csio, size_t oreceived, size_t data_segment_len)
{
        switch (csio->ccb_h.flags & CAM_DATA_MASK) {
        case CAM_DATA_BIO:
                icl_pdu_get_bio(response, pdu_offset,
                    (struct bio *)csio->data_ptr, oreceived, data_segment_len);
                break;
        case CAM_DATA_VADDR:
                icl_pdu_get_data(response, pdu_offset,
                    csio->data_ptr + oreceived, data_segment_len);
                break;
        default:
                __assert_unreachable();
        }
}

static void
iscsi_pdu_handle_data_in(struct icl_pdu *response)
{
        struct iscsi_bhs_data_in *bhsdi;
        struct iscsi_outstanding *io;
        struct iscsi_session *is;
        union ccb *ccb;
        struct ccb_scsiio *csio;
        size_t data_segment_len, received, oreceived;

        is = PDU_SESSION(response);
        bhsdi = (struct iscsi_bhs_data_in *)response->ip_bhs;
        io = iscsi_outstanding_find(is, bhsdi->bhsdi_initiator_task_tag);
        if (io == NULL || io->io_ccb == NULL) {
                ISCSI_SESSION_WARN(is, "bad itt 0x%x", bhsdi->bhsdi_initiator_task_tag);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                ISCSI_SESSION_UNLOCK(is);
                return;
        }

        if (io->io_datasn != ntohl(bhsdi->bhsdi_datasn)) {
                ISCSI_SESSION_WARN(is, "received Data-In PDU with "
                    "DataSN %u, while expected %u; dropping connection",
                    ntohl(bhsdi->bhsdi_datasn), io->io_datasn);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                ISCSI_SESSION_UNLOCK(is);
                return;
        }
        io->io_datasn += response->ip_additional_pdus + 1;

        data_segment_len = icl_pdu_data_segment_length(response);
        if (data_segment_len == 0) {
                /*
                 * "The sending of 0 length data segments should be avoided,
                 * but initiators and targets MUST be able to properly receive
                 * 0 length data segments."
                 */
                ISCSI_SESSION_UNLOCK(is);
                icl_pdu_free(response);
                return;
        }

        /*
         * We need to track this for security reasons - without it, malicious target
         * could respond to SCSI READ without sending Data-In PDUs, which would result
         * in read operation on the initiator side returning random kernel data.
         */
        if (ntohl(bhsdi->bhsdi_buffer_offset) != io->io_received) {
                ISCSI_SESSION_WARN(is, "data out of order; expected offset %zd, got %zd",
                    io->io_received, (size_t)ntohl(bhsdi->bhsdi_buffer_offset));
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                ISCSI_SESSION_UNLOCK(is);
                return;
        }

        ccb = io->io_ccb;
        csio = &ccb->csio;

        if (io->io_received + data_segment_len > csio->dxfer_len) {
                ISCSI_SESSION_WARN(is, "oversize data segment (%zd bytes "
                    "at offset %zd, buffer is %d)",
                    data_segment_len, io->io_received, csio->dxfer_len);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                ISCSI_SESSION_UNLOCK(is);
                return;
        }

        oreceived = io->io_received;
        io->io_received += data_segment_len;
        received = io->io_received;
        if ((bhsdi->bhsdi_flags & BHSDI_FLAGS_S) != 0)
                iscsi_outstanding_remove(is, io);
        ISCSI_SESSION_UNLOCK(is);

        iscsi_pdu_get_data_csio(response, 0, csio, oreceived, data_segment_len);

        /*
         * XXX: Check F.
         */
        if ((bhsdi->bhsdi_flags & BHSDI_FLAGS_S) == 0) {
                /*
                 * Nothing more to do.
                 */
                icl_pdu_free(response);
                return;
        }

        //ISCSI_SESSION_DEBUG(is, "got S flag; status 0x%x", bhsdi->bhsdi_status);
        if (bhsdi->bhsdi_status == 0) {
                ccb->ccb_h.status = CAM_REQ_CMP;
        } else {
                if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                        xpt_freeze_devq(ccb->ccb_h.path, 1);
                        ISCSI_SESSION_DEBUG(is, "freezing devq");
                }
                ccb->ccb_h.status = CAM_SCSI_STATUS_ERROR | CAM_DEV_QFRZN;
                csio->scsi_status = bhsdi->bhsdi_status;
        }

        if ((csio->ccb_h.flags & CAM_DIR_MASK) == CAM_DIR_IN) {
                KASSERT(received <= csio->dxfer_len,
                    ("received > csio->dxfer_len"));
                if (received < csio->dxfer_len) {
                        csio->resid = ntohl(bhsdi->bhsdi_residual_count);
                        if (csio->resid != csio->dxfer_len - received) {
                                ISCSI_SESSION_WARN(is, "underflow mismatch: "
                                    "target indicates %d, we calculated %zd",
                                    csio->resid, csio->dxfer_len - received);
                        }
                        csio->resid = csio->dxfer_len - received;
                }
        }

        xpt_done(ccb);
        icl_pdu_free(response);
}

static void
iscsi_pdu_handle_logout_response(struct icl_pdu *response)
{

        ISCSI_SESSION_DEBUG(PDU_SESSION(response), "logout response");
        icl_pdu_free(response);
}

static int
iscsi_pdu_append_data_csio(struct icl_pdu *request, struct ccb_scsiio *csio,
    size_t off, size_t len, int how)
{
        switch (csio->ccb_h.flags & CAM_DATA_MASK) {
        case CAM_DATA_BIO:
                return (icl_pdu_append_bio(request,
                        (struct bio *)csio->data_ptr, off, len, how));
        case CAM_DATA_VADDR:
                return (icl_pdu_append_data(request, csio->data_ptr + off, len,
                    how));
        default:
                __assert_unreachable();
        }
}

static void
iscsi_pdu_handle_r2t(struct icl_pdu *response)
{
        struct icl_pdu *request;
        struct iscsi_session *is;
        struct iscsi_bhs_r2t *bhsr2t;
        struct iscsi_bhs_data_out *bhsdo;
        struct iscsi_outstanding *io;
        struct ccb_scsiio *csio;
        size_t off, len, max_send_data_segment_length, total_len;
        int error;
        uint32_t datasn = 0;

        is = PDU_SESSION(response);

        bhsr2t = (struct iscsi_bhs_r2t *)response->ip_bhs;
        io = iscsi_outstanding_find(is, bhsr2t->bhsr2t_initiator_task_tag);
        if (io == NULL || io->io_ccb == NULL) {
                ISCSI_SESSION_WARN(is, "bad itt 0x%x; reconnecting",
                    bhsr2t->bhsr2t_initiator_task_tag);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                return;
        }

        csio = &io->io_ccb->csio;

        if ((csio->ccb_h.flags & CAM_DIR_MASK) != CAM_DIR_OUT) {
                ISCSI_SESSION_WARN(is, "received R2T for read command; reconnecting");
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                return;
        }

        /*
         * XXX: Verify R2TSN.
         */

        off = ntohl(bhsr2t->bhsr2t_buffer_offset);
        if (off > csio->dxfer_len) {
                ISCSI_SESSION_WARN(is, "target requested invalid offset "
                    "%zd, buffer is %d; reconnecting", off, csio->dxfer_len);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                return;
        }

        total_len = ntohl(bhsr2t->bhsr2t_desired_data_transfer_length);
        if (total_len == 0 || total_len > csio->dxfer_len) {
                ISCSI_SESSION_WARN(is, "target requested invalid length "
                    "%zd, buffer is %d; reconnecting", total_len, csio->dxfer_len);
                icl_pdu_free(response);
                iscsi_session_reconnect(is);
                return;
        }

        //ISCSI_SESSION_DEBUG(is, "r2t; off %zd, len %zd", off, total_len);

        if (is->is_conn->ic_hw_isomax != 0)
                max_send_data_segment_length = is->is_conn->ic_hw_isomax;
        else
                max_send_data_segment_length =
                    is->is_conn->ic_max_send_data_segment_length;
        for (;;) {
                len = total_len;

                if (len > max_send_data_segment_length)
                        len = max_send_data_segment_length;

                if (off + len > csio->dxfer_len) {
                        ISCSI_SESSION_WARN(is, "target requested invalid "
                            "length/offset %zd, buffer is %d; reconnecting",
                            off + len, csio->dxfer_len);
                        icl_pdu_free(response);
                        iscsi_session_reconnect(is);
                        return;
                }

                request = icl_pdu_new(response->ip_conn, M_NOWAIT);
                if (request == NULL) {
                        icl_pdu_free(response);
                        iscsi_session_reconnect(is);
                        return;
                }

                bhsdo = (struct iscsi_bhs_data_out *)request->ip_bhs;
                bhsdo->bhsdo_opcode = ISCSI_BHS_OPCODE_SCSI_DATA_OUT;
                bhsdo->bhsdo_lun = bhsr2t->bhsr2t_lun;
                bhsdo->bhsdo_initiator_task_tag =
                    bhsr2t->bhsr2t_initiator_task_tag;
                bhsdo->bhsdo_target_transfer_tag =
                    bhsr2t->bhsr2t_target_transfer_tag;
                bhsdo->bhsdo_datasn = htonl(datasn);
                bhsdo->bhsdo_buffer_offset = htonl(off);
                error = iscsi_pdu_append_data_csio(request, csio, off, len,
                    M_NOWAIT | ICL_NOCOPY);
                if (error != 0) {
                        ISCSI_SESSION_WARN(is, "failed to allocate memory; "
                            "reconnecting");
                        icl_pdu_free(request);
                        icl_pdu_free(response);
                        iscsi_session_reconnect(is);
                        return;
                }

                datasn += howmany(len,
                    is->is_conn->ic_max_send_data_segment_length);
                off += len;
                total_len -= len;

                if (total_len == 0) {
                        bhsdo->bhsdo_flags |= BHSDO_FLAGS_F;
                        //ISCSI_SESSION_DEBUG(is, "setting F, off %zd", off);
                } else {
                        //ISCSI_SESSION_DEBUG(is, "not finished, off %zd", off);
                }

                iscsi_pdu_queue_locked(request);

                if (total_len == 0)
                        break;
        }

        icl_pdu_free(response);
}

static void
iscsi_pdu_handle_async_message(struct icl_pdu *response)
{
        struct iscsi_bhs_asynchronous_message *bhsam;
        struct iscsi_session *is;

        is = PDU_SESSION(response);
        bhsam = (struct iscsi_bhs_asynchronous_message *)response->ip_bhs;
        switch (bhsam->bhsam_async_event) {
        case BHSAM_EVENT_TARGET_REQUESTS_LOGOUT:
                ISCSI_SESSION_WARN(is, "target requests logout; removing session");
                iscsi_session_logout(is);
                iscsi_session_terminate(is);
                break;
        case BHSAM_EVENT_TARGET_TERMINATES_CONNECTION:
                ISCSI_SESSION_WARN(is, "target indicates it will drop the connection");
                break;
        case BHSAM_EVENT_TARGET_TERMINATES_SESSION:
                ISCSI_SESSION_WARN(is, "target indicates it will drop the session");
                break;
        default:
                /*
                 * XXX: Technically, we're obligated to also handle
                 *      parameter renegotiation.
                 */
                ISCSI_SESSION_WARN(is, "ignoring AsyncEvent %d", bhsam->bhsam_async_event);
                break;
        }

        icl_pdu_free(response);
}

static void
iscsi_pdu_handle_reject(struct icl_pdu *response)
{
        struct iscsi_bhs_reject *bhsr;
        struct iscsi_session *is;

        is = PDU_SESSION(response);
        bhsr = (struct iscsi_bhs_reject *)response->ip_bhs;
        ISCSI_SESSION_WARN(is, "received Reject PDU, reason 0x%x; protocol error?",
            bhsr->bhsr_reason);

        icl_pdu_free(response);
}

static int
iscsi_ioctl_daemon_wait(struct iscsi_softc *sc,
    struct iscsi_daemon_request *request, bool freebsd13)
{
        struct iscsi_session *is;
        int error;

        sx_slock(&sc->sc_lock);
        for (;;) {
                TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                        ISCSI_SESSION_LOCK(is);
                        if (is->is_conf.isc_enable == 0 &&
                            is->is_conf.isc_discovery == 0) {
                                ISCSI_SESSION_UNLOCK(is);
                                continue;
                        }
                        if (is->is_waiting_for_iscsid)
                                break;
                        ISCSI_SESSION_UNLOCK(is);
                }

                if (is == NULL) {
                        if (sc->sc_unloading) {
                                sx_sunlock(&sc->sc_lock);
                                return (ENXIO);
                        }

                        /*
                         * No session requires attention from iscsid(8); wait.
                         */
                        error = cv_wait_sig(&sc->sc_cv, &sc->sc_lock);
                        if (error != 0) {
                                sx_sunlock(&sc->sc_lock);
                                return (error);
                        }
                        continue;
                }

                is->is_waiting_for_iscsid = false;
                is->is_login_phase = true;
                is->is_reason[0] = '\0';
                ISCSI_SESSION_UNLOCK(is);

                request->idr_session_id = is->is_id;
                memcpy(&request->idr_isid, &is->is_isid,
                    sizeof(request->idr_isid));
                request->idr_tsih = 0;  /* New or reinstated session. */
                memcpy(&request->idr_conf, &is->is_conf,
                    sizeof(request->idr_conf));

#ifdef COMPAT_FREEBSD13
                if (freebsd13) {
                        struct icl_drv_limits idl;
                        struct iscsi_daemon_request13 *request13;

                        error = icl_limits(is->is_conf.isc_offload,
                            is->is_conf.isc_iser, 0, &idl);
                        if (error != 0) {
                                ISCSI_SESSION_WARN(is, "icl_limits for "
                                    "offload \"%s\" failed with error %d",
                                    is->is_conf.isc_offload, error);
                                sx_sunlock(&sc->sc_lock);
                                return (error);
                        }
                        request13 = (struct iscsi_daemon_request13 *)request;
                        request13->idr_limits.isl_max_recv_data_segment_length =
                            idl.idl_max_recv_data_segment_length;
                        request13->idr_limits.isl_max_send_data_segment_length =
                            idl.idl_max_send_data_segment_length;
                        request13->idr_limits.isl_max_burst_length =
                            idl.idl_max_burst_length;
                        request13->idr_limits.isl_first_burst_length =
                            idl.idl_first_burst_length;
                }
#endif
                sx_sunlock(&sc->sc_lock);
                return (0);
        }
}

static int
iscsi_ioctl_daemon_limits(struct iscsi_softc *sc,
    struct iscsi_daemon_limits *limits)
{
        struct icl_drv_limits idl;
        struct iscsi_session *is;
        int error;

        sx_slock(&sc->sc_lock);

        /*
         * Find the session to fetch limits for.
         */
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                if (is->is_id == limits->idl_session_id)
                        break;
        }
        if (is == NULL) {
                sx_sunlock(&sc->sc_lock);
                return (ESRCH);
        }

        error = icl_limits(is->is_conf.isc_offload, is->is_conf.isc_iser,
            limits->idl_socket, &idl);
        sx_sunlock(&sc->sc_lock);
        if (error != 0) {
                ISCSI_SESSION_WARN(is, "icl_limits for offload \"%s\" "
                    "failed with error %d", is->is_conf.isc_offload, error);
                return (error);
        }
        limits->idl_limits.isl_max_recv_data_segment_length =
            idl.idl_max_recv_data_segment_length;
        limits->idl_limits.isl_max_send_data_segment_length =
            idl.idl_max_send_data_segment_length;
        limits->idl_limits.isl_max_burst_length =
            idl.idl_max_burst_length;
        limits->idl_limits.isl_first_burst_length =
            idl.idl_first_burst_length;
        
        return (0);
}

static int
iscsi_ioctl_daemon_handoff(struct iscsi_softc *sc,
    struct iscsi_daemon_handoff *handoff)
{
        struct iscsi_session *is;
        struct icl_conn *ic;
        int error;

        sx_slock(&sc->sc_lock);

        /*
         * Find the session to hand off socket to.
         */
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                if (is->is_id == handoff->idh_session_id)
                        break;
        }
        if (is == NULL) {
                sx_sunlock(&sc->sc_lock);
                return (ESRCH);
        }
        ISCSI_SESSION_LOCK(is);
        ic = is->is_conn;
        if (is->is_conf.isc_discovery || is->is_terminating) {
                ISCSI_SESSION_UNLOCK(is);
                sx_sunlock(&sc->sc_lock);
                return (EINVAL);
        }
        if (is->is_connected) {
                /*
                 * This might have happened because another iscsid(8)
                 * instance handed off the connection in the meantime.
                 * Just return.
                 */
                ISCSI_SESSION_WARN(is, "handoff on already connected "
                    "session");
                ISCSI_SESSION_UNLOCK(is);
                sx_sunlock(&sc->sc_lock);
                return (EBUSY);
        }

        strlcpy(is->is_target_alias, handoff->idh_target_alias,
            sizeof(is->is_target_alias));
        is->is_tsih = handoff->idh_tsih;
        is->is_statsn = handoff->idh_statsn;
        is->is_protocol_level = handoff->idh_protocol_level;
        is->is_initial_r2t = handoff->idh_initial_r2t;
        is->is_immediate_data = handoff->idh_immediate_data;

        ic->ic_max_recv_data_segment_length =
            handoff->idh_max_recv_data_segment_length;
        ic->ic_max_send_data_segment_length =
            handoff->idh_max_send_data_segment_length;
        is->is_max_burst_length = handoff->idh_max_burst_length;
        is->is_first_burst_length = handoff->idh_first_burst_length;

        if (handoff->idh_header_digest == ISCSI_DIGEST_CRC32C)
                ic->ic_header_crc32c = true;
        else
                ic->ic_header_crc32c = false;
        if (handoff->idh_data_digest == ISCSI_DIGEST_CRC32C)
                ic->ic_data_crc32c = true;
        else
                ic->ic_data_crc32c = false;
        ic->ic_maxtags = maxtags;

        is->is_cmdsn = 0;
        is->is_expcmdsn = 0;
        is->is_maxcmdsn = 0;
        is->is_waiting_for_iscsid = false;
        is->is_login_phase = false;
        is->is_timeout = 0;
        is->is_ping_timeout = is->is_conf.isc_ping_timeout;
        if (is->is_ping_timeout < 0)
                is->is_ping_timeout = ping_timeout;
        is->is_login_timeout = is->is_conf.isc_login_timeout;
        if (is->is_login_timeout < 0)
                is->is_login_timeout = login_timeout;
        is->is_connected = true;
        is->is_reason[0] = '\0';

        ISCSI_SESSION_UNLOCK(is);

        /*
         * If we're going through the proxy, the idh_socket will be 0,
         * and the ICL module can simply ignore this call.  It can also
         * use it to determine it's no longer in the Login phase.
         */
        error = icl_conn_handoff(ic, handoff->idh_socket);
        if (error != 0) {
                sx_sunlock(&sc->sc_lock);
                iscsi_session_terminate(is);
                return (error);
        }

        sx_sunlock(&sc->sc_lock);

        if (is->is_sim != NULL) {
                /*
                 * When reconnecting, there already is SIM allocated for the session.
                 */
                KASSERT(is->is_simq_frozen, ("reconnect without frozen simq"));
                ISCSI_SESSION_LOCK(is);
                ISCSI_SESSION_DEBUG(is, "releasing");
                is->is_simq_frozen = false;
                xpt_release_simq(is->is_sim, 1);
                ISCSI_SESSION_UNLOCK(is);

        } else {
                ISCSI_SESSION_LOCK(is);
                is->is_devq = cam_simq_alloc(ic->ic_maxtags);
                if (is->is_devq == NULL) {
                        ISCSI_SESSION_UNLOCK(is);
                        ISCSI_SESSION_WARN(is, "failed to allocate simq");
                        iscsi_session_terminate(is);
                        return (ENOMEM);
                }

                is->is_sim = cam_sim_alloc(iscsi_action, NULL, "iscsi",
                    is, is->is_id /* unit */, &is->is_lock,
                    1, ic->ic_maxtags, is->is_devq);
                if (is->is_sim == NULL) {
                        ISCSI_SESSION_UNLOCK(is);
                        ISCSI_SESSION_WARN(is, "failed to allocate SIM");
                        cam_simq_free(is->is_devq);
                        iscsi_session_terminate(is);
                        return (ENOMEM);
                }

                if (xpt_bus_register(is->is_sim, NULL, 0) != 0) {
                        ISCSI_SESSION_UNLOCK(is);
                        ISCSI_SESSION_WARN(is, "failed to register bus");
                        iscsi_session_terminate(is);
                        return (ENOMEM);
                }

                error = xpt_create_path(&is->is_path, /*periph*/NULL,
                    cam_sim_path(is->is_sim), CAM_TARGET_WILDCARD,
                    CAM_LUN_WILDCARD);
                if (error != CAM_REQ_CMP) {
                        ISCSI_SESSION_UNLOCK(is);
                        ISCSI_SESSION_WARN(is, "failed to create path");
                        iscsi_session_terminate(is);
                        return (ENOMEM);
                }
                ISCSI_SESSION_UNLOCK(is);
        }

        return (0);
}

static int
iscsi_ioctl_daemon_fail(struct iscsi_softc *sc,
    struct iscsi_daemon_fail *fail)
{
        struct iscsi_session *is;

        sx_slock(&sc->sc_lock);

        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                if (is->is_id == fail->idf_session_id)
                        break;
        }
        if (is == NULL) {
                sx_sunlock(&sc->sc_lock);
                return (ESRCH);
        }
        ISCSI_SESSION_LOCK(is);
        ISCSI_SESSION_DEBUG(is, "iscsid(8) failed: %s",
            fail->idf_reason);
        strlcpy(is->is_reason, fail->idf_reason, sizeof(is->is_reason));
        //is->is_waiting_for_iscsid = false;
        //is->is_login_phase = true;
        //iscsi_session_reconnect(is);
        ISCSI_SESSION_UNLOCK(is);
        sx_sunlock(&sc->sc_lock);

        return (0);
}

#ifdef ICL_KERNEL_PROXY
static int
iscsi_ioctl_daemon_connect(struct iscsi_softc *sc,
    struct iscsi_daemon_connect *idc)
{
        struct iscsi_session *is;
        struct sockaddr *from_sa, *to_sa;
        int error;

        sx_slock(&sc->sc_lock);
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                if (is->is_id == idc->idc_session_id)
                        break;
        }
        if (is == NULL) {
                sx_sunlock(&sc->sc_lock);
                return (ESRCH);
        }
        sx_sunlock(&sc->sc_lock);

        if (idc->idc_from_addrlen > 0) {
                error = getsockaddr(&from_sa, (void *)idc->idc_from_addr, idc->idc_from_addrlen);
                if (error != 0) {
                        ISCSI_SESSION_WARN(is,
                            "getsockaddr failed with error %d", error);
                        return (error);
                }
        } else {
                from_sa = NULL;
        }
        error = getsockaddr(&to_sa, (void *)idc->idc_to_addr, idc->idc_to_addrlen);
        if (error != 0) {
                ISCSI_SESSION_WARN(is, "getsockaddr failed with error %d",
                    error);
                free(from_sa, M_SONAME);
                return (error);
        }

        ISCSI_SESSION_LOCK(is);
        is->is_statsn = 0;
        is->is_cmdsn = 0;
        is->is_expcmdsn = 0;
        is->is_maxcmdsn = 0;
        is->is_waiting_for_iscsid = false;
        is->is_login_phase = true;
        is->is_timeout = 0;
        ISCSI_SESSION_UNLOCK(is);

        error = icl_conn_connect(is->is_conn, idc->idc_domain,
            idc->idc_socktype, idc->idc_protocol, from_sa, to_sa);
        free(from_sa, M_SONAME);
        free(to_sa, M_SONAME);

        /*
         * Digests are always disabled during login phase.
         */
        is->is_conn->ic_header_crc32c = false;
        is->is_conn->ic_data_crc32c = false;

        return (error);
}

static int
iscsi_ioctl_daemon_send(struct iscsi_softc *sc,
    struct iscsi_daemon_send *ids)
{
        struct iscsi_session *is;
        struct icl_pdu *ip;
        size_t datalen;
        void *data;
        int error;

        sx_slock(&sc->sc_lock);
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                if (is->is_id == ids->ids_session_id)
                        break;
        }
        if (is == NULL) {
                sx_sunlock(&sc->sc_lock);
                return (ESRCH);
        }
        sx_sunlock(&sc->sc_lock);

        if (is->is_login_phase == false)
                return (EBUSY);

        if (is->is_terminating || is->is_reconnecting)
                return (EIO);

        datalen = ids->ids_data_segment_len;
        if (datalen > is->is_conn->ic_max_send_data_segment_length)
                return (EINVAL);
        if (datalen > 0) {
                data = malloc(datalen, M_ISCSI, M_WAITOK);
                error = copyin(ids->ids_data_segment, data, datalen);
                if (error != 0) {
                        free(data, M_ISCSI);
                        return (error);
                }
        }

        ip = icl_pdu_new(is->is_conn, M_WAITOK);
        memcpy(ip->ip_bhs, ids->ids_bhs, sizeof(*ip->ip_bhs));
        if (datalen > 0) {
                error = icl_pdu_append_data(ip, data, datalen, M_WAITOK);
                KASSERT(error == 0, ("icl_pdu_append_data(..., M_WAITOK) failed"));
                free(data, M_ISCSI);
        }
        iscsi_pdu_queue(ip);

        return (0);
}

static int
iscsi_ioctl_daemon_receive(struct iscsi_softc *sc,
    struct iscsi_daemon_receive *idr)
{
        struct iscsi_session *is;
        struct icl_pdu *ip;
        void *data;
        int error;

        sx_slock(&sc->sc_lock);
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                if (is->is_id == idr->idr_session_id)
                        break;
        }
        if (is == NULL) {
                sx_sunlock(&sc->sc_lock);
                return (ESRCH);
        }
        sx_sunlock(&sc->sc_lock);

        if (is->is_login_phase == false)
                return (EBUSY);

        ISCSI_SESSION_LOCK(is);
        while (is->is_login_pdu == NULL &&
            is->is_terminating == false &&
            is->is_reconnecting == false) {
                error = cv_wait_sig(&is->is_login_cv, &is->is_lock);
                if (error != 0) {
                        ISCSI_SESSION_UNLOCK(is);
                        return (error);
                }
        }
        if (is->is_terminating || is->is_reconnecting) {
                ISCSI_SESSION_UNLOCK(is);
                return (EIO);
        }
        ip = is->is_login_pdu;
        is->is_login_pdu = NULL;
        ISCSI_SESSION_UNLOCK(is);

        if (ip->ip_data_len > idr->idr_data_segment_len) {
                icl_pdu_free(ip);
                return (EMSGSIZE);
        }

        error = copyout(ip->ip_bhs, idr->idr_bhs, sizeof(*ip->ip_bhs));
        if (error == 0 && ip->ip_data_len > 0) {
                data = malloc(ip->ip_data_len, M_ISCSI, M_WAITOK);
                icl_pdu_get_data(ip, 0, data, ip->ip_data_len);
                error = copyout(data, idr->idr_data_segment, ip->ip_data_len);
                free(data, M_ISCSI);
        }

        icl_pdu_free(ip);

        return (error);
}
#endif /* ICL_KERNEL_PROXY */

static void
iscsi_sanitize_session_conf(struct iscsi_session_conf *isc)
{
        /*
         * Just make sure all the fields are null-terminated.
         *
         * XXX: This is not particularly secure.  We should
         *      create our own conf and then copy in relevant
         *      fields.
         */
        isc->isc_initiator[ISCSI_NAME_LEN - 1] = '\0';
        isc->isc_initiator_addr[ISCSI_ADDR_LEN - 1] = '\0';
        isc->isc_initiator_alias[ISCSI_ALIAS_LEN - 1] = '\0';
        isc->isc_target[ISCSI_NAME_LEN - 1] = '\0';
        isc->isc_target_addr[ISCSI_ADDR_LEN - 1] = '\0';
        isc->isc_user[ISCSI_NAME_LEN - 1] = '\0';
        isc->isc_secret[ISCSI_SECRET_LEN - 1] = '\0';
        isc->isc_mutual_user[ISCSI_NAME_LEN - 1] = '\0';
        isc->isc_mutual_secret[ISCSI_SECRET_LEN - 1] = '\0';
}

static bool
iscsi_valid_session_conf(const struct iscsi_session_conf *isc)
{

        if (isc->isc_initiator[0] == '\0') {
                ISCSI_DEBUG("empty isc_initiator");
                return (false);
        }

        if (isc->isc_target_addr[0] == '\0') {
                ISCSI_DEBUG("empty isc_target_addr");
                return (false);
        }

        if (isc->isc_discovery != 0 && isc->isc_target[0] != 0) {
                ISCSI_DEBUG("non-empty isc_target for discovery session");
                return (false);
        }

        if (isc->isc_discovery == 0 && isc->isc_target[0] == 0) {
                ISCSI_DEBUG("empty isc_target for non-discovery session");
                return (false);
        }

        return (true);
}

static int
iscsi_ioctl_session_add(struct iscsi_softc *sc, struct iscsi_session_add *isa)
{
        struct iscsi_session *is;
        const struct iscsi_session *is2;
        int error;
        sbintime_t sbt, pr;

        iscsi_sanitize_session_conf(&isa->isa_conf);
        if (iscsi_valid_session_conf(&isa->isa_conf) == false)
                return (EINVAL);

        is = malloc(sizeof(*is), M_ISCSI, M_ZERO | M_WAITOK);
        memcpy(&is->is_conf, &isa->isa_conf, sizeof(is->is_conf));

        sx_xlock(&sc->sc_lock);

        /*
         * Prevent duplicates.
         */
        TAILQ_FOREACH(is2, &sc->sc_sessions, is_next) {
                if (!!is->is_conf.isc_discovery !=
                    !!is2->is_conf.isc_discovery)
                        continue;

                if (strcmp(is->is_conf.isc_target_addr,
                    is2->is_conf.isc_target_addr) != 0)
                        continue;

                if (is->is_conf.isc_discovery == 0 &&
                    strcmp(is->is_conf.isc_target,
                    is2->is_conf.isc_target) != 0)
                        continue;

                sx_xunlock(&sc->sc_lock);
                free(is, M_ISCSI);
                return (EBUSY);
        }

        is->is_conn = icl_new_conn(is->is_conf.isc_offload,
            is->is_conf.isc_iser, "iscsi", &is->is_lock);
        if (is->is_conn == NULL) {
                sx_xunlock(&sc->sc_lock);
                free(is, M_ISCSI);
                return (EINVAL);
        }
        is->is_conn->ic_receive = iscsi_receive_callback;
        is->is_conn->ic_error = iscsi_error_callback;
        is->is_conn->ic_prv0 = is;
        TAILQ_INIT(&is->is_outstanding);
        STAILQ_INIT(&is->is_postponed);
        mtx_init(&is->is_lock, "iscsi_lock", NULL, MTX_DEF);
        cv_init(&is->is_maintenance_cv, "iscsi_mt");
#ifdef ICL_KERNEL_PROXY
        cv_init(&is->is_login_cv, "iscsi_login");
#endif

        /*
         * Set some default values, from RFC 3720, section 12.
         *
         * These values are updated by the handoff IOCTL, but are
         * needed prior to the handoff to support sending the ISER
         * login PDU.
         */
        is->is_conn->ic_max_recv_data_segment_length = 8192;
        is->is_conn->ic_max_send_data_segment_length = 8192;
        is->is_max_burst_length = 262144;
        is->is_first_burst_length = 65536;

        is->is_softc = sc;
        sc->sc_last_session_id++;
        is->is_id = sc->sc_last_session_id;
        is->is_isid[0] = 0x80; /* RFC 3720, 10.12.5: 10b, "Random" ISID. */
        arc4rand(&is->is_isid[1], 5, 0);
        is->is_tsih = 0;
        callout_init(&is->is_callout, 1);

        error = kthread_add(iscsi_maintenance_thread, is, NULL, NULL, 0, 0, "iscsimt");
        if (error != 0) {
                ISCSI_SESSION_WARN(is, "kthread_add(9) failed with error %d", error);
                sx_xunlock(&sc->sc_lock);
                return (error);
        }
        is->is_ping_timeout = is->is_conf.isc_ping_timeout;
        if (is->is_ping_timeout < 0)
                is->is_ping_timeout = ping_timeout;
        is->is_login_timeout = is->is_conf.isc_login_timeout;
        if (is->is_login_timeout < 0)
                is->is_login_timeout = login_timeout;

        sbt = mstosbt(995);
        pr = mstosbt(10);
        callout_reset_sbt(&is->is_callout, sbt, pr, iscsi_callout, is, 0);
        TAILQ_INSERT_TAIL(&sc->sc_sessions, is, is_next);

        ISCSI_SESSION_LOCK(is);
        /*
         * Don't notify iscsid(8) if the session is disabled and it's not
         * a discovery session,
         */
        if (is->is_conf.isc_enable == 0 && is->is_conf.isc_discovery == 0) {
                ISCSI_SESSION_UNLOCK(is);
                sx_xunlock(&sc->sc_lock);
                return (0);
        }

        is->is_waiting_for_iscsid = true;
        strlcpy(is->is_reason, "Waiting for iscsid(8)", sizeof(is->is_reason));
        ISCSI_SESSION_UNLOCK(is);
        cv_signal(&sc->sc_cv);
        sx_xunlock(&sc->sc_lock);
        return (0);
}

static bool
iscsi_session_conf_matches(unsigned int id1, const struct iscsi_session_conf *c1,
    unsigned int id2, const struct iscsi_session_conf *c2)
{

        if (id2 != 0 && id2 != id1)
                return (false);
        if (c2->isc_target[0] != '\0' &&
            strcmp(c1->isc_target, c2->isc_target) != 0)
                return (false);
        if (c2->isc_target_addr[0] != '\0' &&
            strcmp(c1->isc_target_addr, c2->isc_target_addr) != 0)
                return (false);
        return (true);
}

static int
iscsi_ioctl_session_remove(struct iscsi_softc *sc,
    struct iscsi_session_remove *isr)
{
        struct iscsi_session *is, *tmp;
        bool found = false;

        iscsi_sanitize_session_conf(&isr->isr_conf);

        sx_xlock(&sc->sc_lock);
        TAILQ_FOREACH_SAFE(is, &sc->sc_sessions, is_next, tmp) {
                ISCSI_SESSION_LOCK(is);
                if (iscsi_session_conf_matches(is->is_id, &is->is_conf,
                    isr->isr_session_id, &isr->isr_conf)) {
                        found = true;
                        iscsi_session_logout(is);
                        iscsi_session_terminate(is);
                }
                ISCSI_SESSION_UNLOCK(is);
        }
        sx_xunlock(&sc->sc_lock);

        if (!found)
                return (ESRCH);

        return (0);
}

static int
iscsi_ioctl_session_list(struct iscsi_softc *sc, struct iscsi_session_list *isl)
{
        int error;
        unsigned int i = 0;
        struct iscsi_session *is;
        struct iscsi_session_state iss;

        sx_slock(&sc->sc_lock);
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                if (i >= isl->isl_nentries) {
                        sx_sunlock(&sc->sc_lock);
                        return (EMSGSIZE);
                }
                memset(&iss, 0, sizeof(iss));
                memcpy(&iss.iss_conf, &is->is_conf, sizeof(iss.iss_conf));
                iss.iss_id = is->is_id;
                strlcpy(iss.iss_target_alias, is->is_target_alias, sizeof(iss.iss_target_alias));
                strlcpy(iss.iss_reason, is->is_reason, sizeof(iss.iss_reason));
                strlcpy(iss.iss_offload, is->is_conn->ic_offload, sizeof(iss.iss_offload));

                if (is->is_conn->ic_header_crc32c)
                        iss.iss_header_digest = ISCSI_DIGEST_CRC32C;
                else
                        iss.iss_header_digest = ISCSI_DIGEST_NONE;

                if (is->is_conn->ic_data_crc32c)
                        iss.iss_data_digest = ISCSI_DIGEST_CRC32C;
                else
                        iss.iss_data_digest = ISCSI_DIGEST_NONE;

                iss.iss_max_send_data_segment_length =
                    is->is_conn->ic_max_send_data_segment_length;
                iss.iss_max_recv_data_segment_length =
                    is->is_conn->ic_max_recv_data_segment_length;
                iss.iss_max_burst_length = is->is_max_burst_length;
                iss.iss_first_burst_length = is->is_first_burst_length;
                iss.iss_immediate_data = is->is_immediate_data;
                iss.iss_connected = is->is_connected;

                error = copyout(&iss, isl->isl_pstates + i, sizeof(iss));
                if (error != 0) {
                        sx_sunlock(&sc->sc_lock);
                        return (error);
                }
                i++;
        }
        sx_sunlock(&sc->sc_lock);

        isl->isl_nentries = i;

        return (0);
}

static int
iscsi_ioctl_session_modify(struct iscsi_softc *sc,
    struct iscsi_session_modify *ism)
{
        struct iscsi_session *is;
        const struct iscsi_session *is2;

        iscsi_sanitize_session_conf(&ism->ism_conf);
        if (iscsi_valid_session_conf(&ism->ism_conf) == false)
                return (EINVAL);

        sx_xlock(&sc->sc_lock);
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                ISCSI_SESSION_LOCK(is);
                if (is->is_id == ism->ism_session_id) {
                        /* Note that the session remains locked. */
                        break;
                }
                ISCSI_SESSION_UNLOCK(is);
        }
        if (is == NULL) {
                sx_xunlock(&sc->sc_lock);
                return (ESRCH);
        }

        /*
         * Prevent duplicates.
         */
        TAILQ_FOREACH(is2, &sc->sc_sessions, is_next) {
                if (is == is2)
                        continue;

                if (!!ism->ism_conf.isc_discovery !=
                    !!is2->is_conf.isc_discovery)
                        continue;

                if (strcmp(ism->ism_conf.isc_target_addr,
                    is2->is_conf.isc_target_addr) != 0)
                        continue;

                if (ism->ism_conf.isc_discovery == 0 &&
                    strcmp(ism->ism_conf.isc_target,
                    is2->is_conf.isc_target) != 0)
                        continue;

                ISCSI_SESSION_UNLOCK(is);
                sx_xunlock(&sc->sc_lock);
                return (EBUSY);
        }

        sx_xunlock(&sc->sc_lock);

        memcpy(&is->is_conf, &ism->ism_conf, sizeof(is->is_conf));
        ISCSI_SESSION_UNLOCK(is);

        iscsi_session_reconnect(is);

        return (0);
}

static int
iscsi_ioctl(struct cdev *dev, u_long cmd, caddr_t arg, int mode,
    struct thread *td)
{
        struct iscsi_softc *sc;

        sc = dev->si_drv1;

        switch (cmd) {
        case ISCSIDWAIT:
                return (iscsi_ioctl_daemon_wait(sc,
                    (struct iscsi_daemon_request *)arg, false));
#ifdef COMPAT_FREEBSD13
        case ISCSIDWAIT13:
                return (iscsi_ioctl_daemon_wait(sc,
                    (struct iscsi_daemon_request *)arg, true));
#endif
        case ISCSIDLIMITS:
                return (iscsi_ioctl_daemon_limits(sc,
                    (struct iscsi_daemon_limits *)arg));
        case ISCSIDHANDOFF:
                return (iscsi_ioctl_daemon_handoff(sc,
                    (struct iscsi_daemon_handoff *)arg));
        case ISCSIDFAIL:
                return (iscsi_ioctl_daemon_fail(sc,
                    (struct iscsi_daemon_fail *)arg));
#ifdef ICL_KERNEL_PROXY
        case ISCSIDCONNECT:
                return (iscsi_ioctl_daemon_connect(sc,
                    (struct iscsi_daemon_connect *)arg));
        case ISCSIDSEND:
                return (iscsi_ioctl_daemon_send(sc,
                    (struct iscsi_daemon_send *)arg));
        case ISCSIDRECEIVE:
                return (iscsi_ioctl_daemon_receive(sc,
                    (struct iscsi_daemon_receive *)arg));
#endif /* ICL_KERNEL_PROXY */
        case ISCSISADD:
                return (iscsi_ioctl_session_add(sc,
                    (struct iscsi_session_add *)arg));
        case ISCSISREMOVE:
                return (iscsi_ioctl_session_remove(sc,
                    (struct iscsi_session_remove *)arg));
        case ISCSISLIST:
                return (iscsi_ioctl_session_list(sc,
                    (struct iscsi_session_list *)arg));
        case ISCSISMODIFY:
                return (iscsi_ioctl_session_modify(sc,
                    (struct iscsi_session_modify *)arg));
        default:
                return (EINVAL);
        }
}

static struct iscsi_outstanding *
iscsi_outstanding_find(struct iscsi_session *is, uint32_t initiator_task_tag)
{
        struct iscsi_outstanding *io;

        ISCSI_SESSION_LOCK_ASSERT(is);

        TAILQ_FOREACH(io, &is->is_outstanding, io_next) {
                if (io->io_initiator_task_tag == initiator_task_tag)
                        return (io);
        }
        return (NULL);
}

static struct iscsi_outstanding *
iscsi_outstanding_find_ccb(struct iscsi_session *is, union ccb *ccb)
{
        struct iscsi_outstanding *io;

        ISCSI_SESSION_LOCK_ASSERT(is);

        TAILQ_FOREACH(io, &is->is_outstanding, io_next) {
                if (io->io_ccb == ccb)
                        return (io);
        }
        return (NULL);
}

static struct iscsi_outstanding *
iscsi_outstanding_add(struct iscsi_session *is, struct icl_pdu *request,
    union ccb *ccb, uint32_t *initiator_task_tagp)
{
        struct iscsi_outstanding *io;
        int error;

        ISCSI_SESSION_LOCK_ASSERT(is);

        io = uma_zalloc(iscsi_outstanding_zone, M_NOWAIT | M_ZERO);
        if (io == NULL) {
                ISCSI_SESSION_WARN(is, "failed to allocate %zd bytes",
                    sizeof(*io));
                return (NULL);
        }

        error = icl_conn_task_setup(is->is_conn, request, &ccb->csio,
            initiator_task_tagp, &io->io_icl_prv);
        if (error != 0) {
                ISCSI_SESSION_WARN(is,
                    "icl_conn_task_setup() failed with error %d", error);
                uma_zfree(iscsi_outstanding_zone, io);
                return (NULL);
        }

        KASSERT(iscsi_outstanding_find(is, *initiator_task_tagp) == NULL,
            ("initiator_task_tag 0x%x already added", *initiator_task_tagp));

        io->io_initiator_task_tag = *initiator_task_tagp;
        io->io_ccb = ccb;
        TAILQ_INSERT_TAIL(&is->is_outstanding, io, io_next);
        return (io);
}

static void
iscsi_outstanding_remove(struct iscsi_session *is, struct iscsi_outstanding *io)
{

        ISCSI_SESSION_LOCK_ASSERT(is);

        icl_conn_task_done(is->is_conn, io->io_icl_prv);
        TAILQ_REMOVE(&is->is_outstanding, io, io_next);
        uma_zfree(iscsi_outstanding_zone, io);
}

static void
iscsi_action_abort(struct iscsi_session *is, union ccb *ccb)
{
        struct icl_pdu *request;
        struct iscsi_bhs_task_management_request *bhstmr;
        struct ccb_abort *cab = &ccb->cab;
        struct iscsi_outstanding *io, *aio;
        uint32_t initiator_task_tag;

        ISCSI_SESSION_LOCK_ASSERT(is);

#if 0
        KASSERT(is->is_login_phase == false, ("%s called during Login Phase", __func__));
#else
        if (is->is_login_phase) {
                ccb->ccb_h.status = CAM_REQ_ABORTED;
                xpt_done(ccb);
                return;
        }
#endif

        aio = iscsi_outstanding_find_ccb(is, cab->abort_ccb);
        if (aio == NULL) {
                ccb->ccb_h.status = CAM_REQ_CMP;
                xpt_done(ccb);
                return;
        }

        request = icl_pdu_new(is->is_conn, M_NOWAIT);
        if (request == NULL) {
                ccb->ccb_h.status = CAM_RESRC_UNAVAIL;
                xpt_done(ccb);
                return;
        }

        initiator_task_tag = is->is_initiator_task_tag++;
        if (initiator_task_tag == 0xffffffff)
                initiator_task_tag = is->is_initiator_task_tag++;

        io = iscsi_outstanding_add(is, request, NULL, &initiator_task_tag);
        if (io == NULL) {
                icl_pdu_free(request);
                ccb->ccb_h.status = CAM_RESRC_UNAVAIL;
                xpt_done(ccb);
                return;
        }
        io->io_referenced_task_tag = aio->io_initiator_task_tag;

        bhstmr = (struct iscsi_bhs_task_management_request *)request->ip_bhs;
        bhstmr->bhstmr_opcode = ISCSI_BHS_OPCODE_TASK_REQUEST;
        bhstmr->bhstmr_function = 0x80 | BHSTMR_FUNCTION_ABORT_TASK;
        bhstmr->bhstmr_lun = htobe64(CAM_EXTLUN_BYTE_SWIZZLE(ccb->ccb_h.target_lun));
        bhstmr->bhstmr_initiator_task_tag = initiator_task_tag;
        bhstmr->bhstmr_referenced_task_tag = aio->io_initiator_task_tag;

        iscsi_pdu_queue_locked(request);
}

static void
iscsi_action_scsiio(struct iscsi_session *is, union ccb *ccb)
{
        struct icl_pdu *request;
        struct iscsi_bhs_scsi_command *bhssc;
        struct ccb_scsiio *csio;
        struct iscsi_outstanding *io;
        size_t len;
        uint32_t initiator_task_tag;
        int error;

        ISCSI_SESSION_LOCK_ASSERT(is);

#if 0
        KASSERT(is->is_login_phase == false, ("%s called during Login Phase", __func__));
#else
        if (is->is_login_phase) {
                ISCSI_SESSION_DEBUG(is, "called during login phase");
                if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                        xpt_freeze_devq(ccb->ccb_h.path, 1);
                        ISCSI_SESSION_DEBUG(is, "freezing devq");
                }
                ccb->ccb_h.status = CAM_REQ_ABORTED | CAM_DEV_QFRZN;
                xpt_done(ccb);
                return;
        }
#endif

        request = icl_pdu_new(is->is_conn, M_NOWAIT);
        if (request == NULL) {
                if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                        xpt_freeze_devq(ccb->ccb_h.path, 1);
                        ISCSI_SESSION_DEBUG(is, "freezing devq");
                }
                ccb->ccb_h.status = CAM_RESRC_UNAVAIL | CAM_DEV_QFRZN;
                xpt_done(ccb);
                return;
        }

        initiator_task_tag = is->is_initiator_task_tag++;
        if (initiator_task_tag == 0xffffffff)
                initiator_task_tag = is->is_initiator_task_tag++;

        io = iscsi_outstanding_add(is, request, ccb, &initiator_task_tag);
        if (io == NULL) {
                icl_pdu_free(request);
                if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                        xpt_freeze_devq(ccb->ccb_h.path, 1);
                        ISCSI_SESSION_DEBUG(is, "freezing devq");
                }
                ccb->ccb_h.status = CAM_RESRC_UNAVAIL | CAM_DEV_QFRZN;
                xpt_done(ccb);
                return;
        }

        csio = &ccb->csio;
        bhssc = (struct iscsi_bhs_scsi_command *)request->ip_bhs;
        bhssc->bhssc_opcode = ISCSI_BHS_OPCODE_SCSI_COMMAND;
        bhssc->bhssc_flags |= BHSSC_FLAGS_F;
        switch (csio->ccb_h.flags & CAM_DIR_MASK) {
        case CAM_DIR_IN:
                bhssc->bhssc_flags |= BHSSC_FLAGS_R;
                break;
        case CAM_DIR_OUT:
                bhssc->bhssc_flags |= BHSSC_FLAGS_W;
                break;
        }

        if ((ccb->ccb_h.flags & CAM_TAG_ACTION_VALID) != 0) {
                switch (csio->tag_action) {
                case MSG_HEAD_OF_Q_TAG:
                        bhssc->bhssc_flags |= BHSSC_FLAGS_ATTR_HOQ;
                        break;
                case MSG_ORDERED_Q_TAG:
                        bhssc->bhssc_flags |= BHSSC_FLAGS_ATTR_ORDERED;
                        break;
                case MSG_ACA_TASK:
                        bhssc->bhssc_flags |= BHSSC_FLAGS_ATTR_ACA;
                        break;
                case MSG_SIMPLE_Q_TAG:
                default:
                        bhssc->bhssc_flags |= BHSSC_FLAGS_ATTR_SIMPLE;
                        break;
                }
        } else
                bhssc->bhssc_flags |= BHSSC_FLAGS_ATTR_UNTAGGED;

        if (is->is_protocol_level >= 2) {
                bhssc->bhssc_pri = (csio->priority << BHSSC_PRI_SHIFT) &
                    BHSSC_PRI_MASK;
        }

        bhssc->bhssc_lun = htobe64(CAM_EXTLUN_BYTE_SWIZZLE(ccb->ccb_h.target_lun));
        bhssc->bhssc_initiator_task_tag = initiator_task_tag;
        bhssc->bhssc_expected_data_transfer_length = htonl(csio->dxfer_len);
        KASSERT(csio->cdb_len <= sizeof(bhssc->bhssc_cdb),
            ("unsupported CDB size %zd", (size_t)csio->cdb_len));

        if (csio->ccb_h.flags & CAM_CDB_POINTER)
                memcpy(&bhssc->bhssc_cdb, csio->cdb_io.cdb_ptr, csio->cdb_len);
        else
                memcpy(&bhssc->bhssc_cdb, csio->cdb_io.cdb_bytes, csio->cdb_len);

        if (is->is_immediate_data &&
            (csio->ccb_h.flags & CAM_DIR_MASK) == CAM_DIR_OUT) {
                len = csio->dxfer_len;
                //ISCSI_SESSION_DEBUG(is, "adding %zd of immediate data", len);
                if (len > is->is_first_burst_length) {
                        ISCSI_SESSION_DEBUG(is, "len %zd -> %d", len, is->is_first_burst_length);
                        len = is->is_first_burst_length;
                }
                if (len > is->is_conn->ic_max_send_data_segment_length) {
                        ISCSI_SESSION_DEBUG(is, "len %zd -> %d", len,
                            is->is_conn->ic_max_send_data_segment_length);
                        len = is->is_conn->ic_max_send_data_segment_length;
                }

                error = iscsi_pdu_append_data_csio(request, csio, 0, len,
                    M_NOWAIT | ICL_NOCOPY);
                if (error != 0) {
                        iscsi_outstanding_remove(is, io);
                        icl_pdu_free(request);
                        if ((ccb->ccb_h.status & CAM_DEV_QFRZN) == 0) {
                                xpt_freeze_devq(ccb->ccb_h.path, 1);
                                ISCSI_SESSION_DEBUG(is, "freezing devq");
                        }
                        ccb->ccb_h.status = CAM_RESRC_UNAVAIL | CAM_DEV_QFRZN;
                        xpt_done(ccb);
                        return;
                }
        }
        iscsi_pdu_queue_locked(request);
}

static void
iscsi_action(struct cam_sim *sim, union ccb *ccb)
{
        struct iscsi_session *is;

        is = cam_sim_softc(sim);

        ISCSI_SESSION_LOCK_ASSERT(is);

        if (is->is_terminating ||
            (is->is_connected == false && fail_on_disconnection)) {
                ccb->ccb_h.status = CAM_DEV_NOT_THERE;
                xpt_done(ccb);
                return;
        }

        /*
         * Make sure CAM doesn't sneak in a CCB just after freezing the queue.
         */
        if (is->is_simq_frozen == true) {
                ccb->ccb_h.status &= ~(CAM_SIM_QUEUED | CAM_STATUS_MASK);
                ccb->ccb_h.status |= CAM_REQUEUE_REQ;
                /* Don't freeze the devq - the SIM queue is already frozen. */
                xpt_done(ccb);
                return;
        }

        switch (ccb->ccb_h.func_code) {
        case XPT_PATH_INQ:
        {
                struct ccb_pathinq *cpi = &ccb->cpi;

                cpi->version_num = 1;
                cpi->hba_inquiry = PI_TAG_ABLE;
                cpi->target_sprt = 0;
                cpi->hba_misc = PIM_EXTLUNS;
                /*
                 * XXX: It shouldn't ever be NULL; this could be turned
                 *      into a KASSERT eventually.
                 */
                if (is->is_conn == NULL)
                        ISCSI_WARN("NULL conn");
                else if (is->is_conn->ic_unmapped)
                        cpi->hba_misc |= PIM_UNMAPPED;
                cpi->hba_eng_cnt = 0;
                cpi->max_target = 0;
                /*
                 * Note that the variable below is only relevant for targets
                 * that don't claim compliance with anything above SPC2, which
                 * means they don't support REPORT_LUNS.
                 */
                cpi->max_lun = 255;
                cpi->initiator_id = ~0;
                strlcpy(cpi->sim_vid, "FreeBSD", SIM_IDLEN);
                strlcpy(cpi->hba_vid, "iSCSI", HBA_IDLEN);
                strlcpy(cpi->dev_name, cam_sim_name(sim), DEV_IDLEN);
                cpi->unit_number = cam_sim_unit(sim);
                cpi->bus_id = cam_sim_bus(sim);
                cpi->base_transfer_speed = 150000; /* XXX */
                cpi->transport = XPORT_ISCSI;
                cpi->transport_version = 0;
                cpi->protocol = PROTO_SCSI;
                cpi->protocol_version = SCSI_REV_SPC3;
                cpi->maxio = maxphys;
                cpi->ccb_h.status = CAM_REQ_CMP;
                break;
        }
        case XPT_GET_TRAN_SETTINGS:
        {
                struct ccb_trans_settings       *cts;
                struct ccb_trans_settings_scsi  *scsi;

                cts = &ccb->cts;
                scsi = &cts->proto_specific.scsi;

                cts->protocol = PROTO_SCSI;
                cts->protocol_version = SCSI_REV_SPC3;
                cts->transport = XPORT_ISCSI;
                cts->transport_version = 0;
                scsi->valid = CTS_SCSI_VALID_TQ;
                scsi->flags = CTS_SCSI_FLAGS_TAG_ENB;
                cts->ccb_h.status = CAM_REQ_CMP;
                break;
        }
        case XPT_CALC_GEOMETRY:
                cam_calc_geometry(&ccb->ccg, /*extended*/1);
                ccb->ccb_h.status = CAM_REQ_CMP;
                break;
#if 0
        /*
         * XXX: What's the point?
         */
        case XPT_RESET_BUS:
        case XPT_TERM_IO:
                ISCSI_SESSION_DEBUG(is, "faking success for reset, abort, or term_io");
                ccb->ccb_h.status = CAM_REQ_CMP;
                break;
#endif
        case XPT_ABORT:
                iscsi_action_abort(is, ccb);
                return;
        case XPT_SCSI_IO:
                iscsi_action_scsiio(is, ccb);
                return;
        default:
#if 0
                ISCSI_SESSION_DEBUG(is, "got unsupported code 0x%x", ccb->ccb_h.func_code);
#endif
                ccb->ccb_h.status = CAM_FUNC_NOTAVAIL;
                break;
        }
        xpt_done(ccb);
}

static void
iscsi_terminate_sessions(struct iscsi_softc *sc)
{
        struct iscsi_session *is;

        sx_slock(&sc->sc_lock);
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next)
                iscsi_session_terminate(is);
        while(!TAILQ_EMPTY(&sc->sc_sessions)) {
                ISCSI_DEBUG("waiting for sessions to terminate");
                cv_wait(&sc->sc_cv, &sc->sc_lock);
        }
        ISCSI_DEBUG("all sessions terminated");
        sx_sunlock(&sc->sc_lock);
}

static void
iscsi_shutdown_pre(struct iscsi_softc *sc, int howto)
{
        struct iscsi_session *is;

        if (!fail_on_shutdown || (howto & RB_NOSYNC) != 0 ||
            SCHEDULER_STOPPED())
                return;

        /*
         * If we have any sessions waiting for reconnection, request
         * maintenance thread to fail them immediately instead of waiting
         * for reconnect timeout.
         *
         * This prevents LUNs with mounted filesystems that are supported
         * by disconnected iSCSI sessions from hanging, however it will
         * fail all queued BIOs.
         */
        ISCSI_DEBUG("forcing failing all disconnected sessions due to shutdown");

        fail_on_disconnection = 1;

        sx_slock(&sc->sc_lock);
        TAILQ_FOREACH(is, &sc->sc_sessions, is_next) {
                ISCSI_SESSION_LOCK(is);
                if (!is->is_connected) {
                        ISCSI_SESSION_DEBUG(is, "force failing disconnected session early");
                        iscsi_session_reconnect(is);
                }
                ISCSI_SESSION_UNLOCK(is);
        }
        sx_sunlock(&sc->sc_lock);
}

static void
iscsi_shutdown_post_sync(struct iscsi_softc *sc, int howto)
{

        if ((howto & RB_NOSYNC) == 0) {
                ISCSI_DEBUG("removing all sessions due to shutdown");
                iscsi_terminate_sessions(sc);
        }
}

static int
iscsi_load(void)
{
        int error;

        sc = malloc(sizeof(*sc), M_ISCSI, M_ZERO | M_WAITOK);
        sx_init(&sc->sc_lock, "iscsi");
        TAILQ_INIT(&sc->sc_sessions);
        cv_init(&sc->sc_cv, "iscsi_cv");

        iscsi_outstanding_zone = uma_zcreate("iscsi_outstanding",
            sizeof(struct iscsi_outstanding), NULL, NULL, NULL, NULL,
            UMA_ALIGN_PTR, 0);

        error = make_dev_p(MAKEDEV_CHECKNAME, &sc->sc_cdev, &iscsi_cdevsw,
            NULL, UID_ROOT, GID_WHEEL, 0600, "iscsi");
        if (error != 0) {
                ISCSI_WARN("failed to create device node, error %d", error);
                return (error);
        }
        sc->sc_cdev->si_drv1 = sc;

        sc->sc_shutdown_pre_eh = EVENTHANDLER_REGISTER(shutdown_pre_sync,
            iscsi_shutdown_pre, sc, SHUTDOWN_PRI_FIRST);
        /*
         * shutdown_post_sync needs to run after filesystem shutdown and before
         * CAM shutdown - otherwise when rebooting with an iSCSI session that is
         * disconnected but has outstanding requests, dashutdown() will hang on
         * cam_periph_runccb().
         */
        sc->sc_shutdown_post_eh = EVENTHANDLER_REGISTER(shutdown_post_sync,
            iscsi_shutdown_post_sync, sc, SHUTDOWN_PRI_DEFAULT - 1);

        return (0);
}

static int
iscsi_unload(void)
{

        /* Awaken any threads asleep in iscsi_ioctl(). */
        sx_xlock(&sc->sc_lock);
        sc->sc_unloading = true;
        cv_signal(&sc->sc_cv);
        sx_xunlock(&sc->sc_lock);

        if (sc->sc_cdev != NULL) {
                ISCSI_DEBUG("removing device node");
                destroy_dev(sc->sc_cdev);
                ISCSI_DEBUG("device node removed");
        }

        if (sc->sc_shutdown_pre_eh != NULL)
                EVENTHANDLER_DEREGISTER(shutdown_pre_sync, sc->sc_shutdown_pre_eh);
        if (sc->sc_shutdown_post_eh != NULL)
                EVENTHANDLER_DEREGISTER(shutdown_post_sync, sc->sc_shutdown_post_eh);

        iscsi_terminate_sessions(sc);

        uma_zdestroy(iscsi_outstanding_zone);
        sx_destroy(&sc->sc_lock);
        cv_destroy(&sc->sc_cv);
        free(sc, M_ISCSI);
        return (0);
}

static int
iscsi_quiesce(void)
{
        sx_slock(&sc->sc_lock);
        if (!TAILQ_EMPTY(&sc->sc_sessions)) {
                sx_sunlock(&sc->sc_lock);
                return (EBUSY);
        }
        sx_sunlock(&sc->sc_lock);
        return (0);
}

static int
iscsi_modevent(module_t mod, int what, void *arg)
{
        int error;

        switch (what) {
        case MOD_LOAD:
                error = iscsi_load();
                break;
        case MOD_UNLOAD:
                error = iscsi_unload();
                break;
        case MOD_QUIESCE:
                error = iscsi_quiesce();
                break;
        default:
                error = EINVAL;
                break;
        }
        return (error);
}

moduledata_t iscsi_data = {
        "iscsi",
        iscsi_modevent,
        0
};

DECLARE_MODULE(iscsi, iscsi_data, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);
MODULE_DEPEND(iscsi, cam, 1, 1, 1);
MODULE_DEPEND(iscsi, icl, 1, 1, 1);