Linux 2.6.17.7

[linux/fpc-iii.git] / drivers / scsi / scsi_transport_iscsi.c

/*
 * iSCSI transport class definitions
 *
 * Copyright (C) IBM Corporation, 2004
 * Copyright (C) Mike Christie, 2004 - 2005
 * Copyright (C) Dmitry Yusupov, 2004 - 2005
 * Copyright (C) Alex Aizman, 2004 - 2005
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
#include <linux/module.h>
#include <linux/mempool.h>
#include <linux/mutex.h>
#include <net/tcp.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_iscsi.h>
#include <scsi/iscsi_if.h>

#define ISCSI_SESSION_ATTRS 8
#define ISCSI_CONN_ATTRS 6

struct iscsi_internal {
        struct scsi_transport_template t;
        struct iscsi_transport *iscsi_transport;
        struct list_head list;
        /*
         * based on transport capabilities, at register time we set these
         * bits to tell the transport class it wants attributes displayed
         * in sysfs or that it can support different iSCSI Data-Path
         * capabilities
         */
        uint32_t param_mask;

        struct class_device cdev;
        /*
         * We do not have any private or other attrs.
         */
        struct transport_container conn_cont;
        struct class_device_attribute *conn_attrs[ISCSI_CONN_ATTRS + 1];
        struct transport_container session_cont;
        struct class_device_attribute *session_attrs[ISCSI_SESSION_ATTRS + 1];
};

/*
 * list of registered transports and lock that must
 * be held while accessing list. The iscsi_transport_lock must
 * be acquired after the rx_queue_mutex.
 */
static LIST_HEAD(iscsi_transports);
static DEFINE_SPINLOCK(iscsi_transport_lock);

#define to_iscsi_internal(tmpl) \
        container_of(tmpl, struct iscsi_internal, t)

#define cdev_to_iscsi_internal(_cdev) \
        container_of(_cdev, struct iscsi_internal, cdev)

static void iscsi_transport_release(struct class_device *cdev)
{
        struct iscsi_internal *priv = cdev_to_iscsi_internal(cdev);
        kfree(priv);
}

/*
 * iscsi_transport_class represents the iscsi_transports that are
 * registered.
 */
static struct class iscsi_transport_class = {
        .name = "iscsi_transport",
        .release = iscsi_transport_release,
};

static ssize_t
show_transport_handle(struct class_device *cdev, char *buf)
{
        struct iscsi_internal *priv = cdev_to_iscsi_internal(cdev);
        return sprintf(buf, "%llu\n", (unsigned long long)iscsi_handle(priv->iscsi_transport));
}
static CLASS_DEVICE_ATTR(handle, S_IRUGO, show_transport_handle, NULL);

#define show_transport_attr(name, format)                               \
static ssize_t                                                          \
show_transport_##name(struct class_device *cdev, char *buf)             \
{                                                                       \
        struct iscsi_internal *priv = cdev_to_iscsi_internal(cdev);     \
        return sprintf(buf, format"\n", priv->iscsi_transport->name);   \
}                                                                       \
static CLASS_DEVICE_ATTR(name, S_IRUGO, show_transport_##name, NULL);

show_transport_attr(caps, "0x%x");
show_transport_attr(max_lun, "%d");
show_transport_attr(max_conn, "%d");
show_transport_attr(max_cmd_len, "%d");

static struct attribute *iscsi_transport_attrs[] = {
        &class_device_attr_handle.attr,
        &class_device_attr_caps.attr,
        &class_device_attr_max_lun.attr,
        &class_device_attr_max_conn.attr,
        &class_device_attr_max_cmd_len.attr,
        NULL,
};

static struct attribute_group iscsi_transport_group = {
        .attrs = iscsi_transport_attrs,
};

static DECLARE_TRANSPORT_CLASS(iscsi_session_class,
                               "iscsi_session",
                               NULL,
                               NULL,
                               NULL);

static DECLARE_TRANSPORT_CLASS(iscsi_connection_class,
                               "iscsi_connection",
                               NULL,
                               NULL,
                               NULL);

static struct sock *nls;
static int daemon_pid;
static DEFINE_MUTEX(rx_queue_mutex);

struct mempool_zone {
        mempool_t *pool;
        atomic_t allocated;
        int size;
        int hiwat;
        struct list_head freequeue;
        spinlock_t freelock;
};

static struct mempool_zone *z_reply;

/*
 * Z_MAX_* - actual mempool size allocated at the mempool_zone_init() time
 * Z_HIWAT_* - zone's high watermark when if_error bit will be set to -ENOMEM
 *             so daemon will notice OOM on NETLINK tranposrt level and will
 *             be able to predict or change operational behavior
 */
#define Z_MAX_REPLY     8
#define Z_HIWAT_REPLY   6
#define Z_MAX_PDU       8
#define Z_HIWAT_PDU     6
#define Z_MAX_ERROR     16
#define Z_HIWAT_ERROR   12

static LIST_HEAD(sesslist);
static DEFINE_SPINLOCK(sesslock);
static LIST_HEAD(connlist);
static DEFINE_SPINLOCK(connlock);

static struct iscsi_cls_session *iscsi_session_lookup(uint64_t handle)
{
        unsigned long flags;
        struct iscsi_cls_session *sess;

        spin_lock_irqsave(&sesslock, flags);
        list_for_each_entry(sess, &sesslist, sess_list) {
                if (sess == iscsi_ptr(handle)) {
                        spin_unlock_irqrestore(&sesslock, flags);
                        return sess;
                }
        }
        spin_unlock_irqrestore(&sesslock, flags);
        return NULL;
}

static struct iscsi_cls_conn *iscsi_conn_lookup(uint64_t handle)
{
        unsigned long flags;
        struct iscsi_cls_conn *conn;

        spin_lock_irqsave(&connlock, flags);
        list_for_each_entry(conn, &connlist, conn_list) {
                if (conn == iscsi_ptr(handle)) {
                        spin_unlock_irqrestore(&connlock, flags);
                        return conn;
                }
        }
        spin_unlock_irqrestore(&connlock, flags);
        return NULL;
}

/*
 * The following functions can be used by LLDs that allocate
 * their own scsi_hosts or by software iscsi LLDs
 */
static void iscsi_session_release(struct device *dev)
{
        struct iscsi_cls_session *session = iscsi_dev_to_session(dev);
        struct iscsi_transport *transport = session->transport;
        struct Scsi_Host *shost;

        shost = iscsi_session_to_shost(session);
        scsi_host_put(shost);
        kfree(session);
        module_put(transport->owner);
}

static int iscsi_is_session_dev(const struct device *dev)
{
        return dev->release == iscsi_session_release;
}

/**
 * iscsi_create_session - create iscsi class session
 * @shost: scsi host
 * @transport: iscsi transport
 *
 * This can be called from a LLD or iscsi_transport
 **/
struct iscsi_cls_session *
iscsi_create_session(struct Scsi_Host *shost, struct iscsi_transport *transport)
{
        struct iscsi_cls_session *session;
        int err;

        if (!try_module_get(transport->owner))
                return NULL;

        session = kzalloc(sizeof(*session), GFP_KERNEL);
        if (!session)
                goto module_put;
        session->transport = transport;

        /* this is released in the dev's release function */
        scsi_host_get(shost);
        snprintf(session->dev.bus_id, BUS_ID_SIZE, "session%u", shost->host_no);
        session->dev.parent = &shost->shost_gendev;
        session->dev.release = iscsi_session_release;
        err = device_register(&session->dev);
        if (err) {
                dev_printk(KERN_ERR, &session->dev, "iscsi: could not "
                           "register session's dev\n");
                goto free_session;
        }
        transport_register_device(&session->dev);

        return session;

free_session:
        kfree(session);
module_put:
        module_put(transport->owner);
        return NULL;
}

EXPORT_SYMBOL_GPL(iscsi_create_session);

/**
 * iscsi_destroy_session - destroy iscsi session
 * @session: iscsi_session
 *
 * Can be called by a LLD or iscsi_transport. There must not be
 * any running connections.
 **/
int iscsi_destroy_session(struct iscsi_cls_session *session)
{
        transport_unregister_device(&session->dev);
        device_unregister(&session->dev);
        return 0;
}

EXPORT_SYMBOL_GPL(iscsi_destroy_session);

static void iscsi_conn_release(struct device *dev)
{
        struct iscsi_cls_conn *conn = iscsi_dev_to_conn(dev);
        struct device *parent = conn->dev.parent;

        kfree(conn);
        put_device(parent);
}

static int iscsi_is_conn_dev(const struct device *dev)
{
        return dev->release == iscsi_conn_release;
}

/**
 * iscsi_create_conn - create iscsi class connection
 * @session: iscsi cls session
 * @cid: connection id
 *
 * This can be called from a LLD or iscsi_transport. The connection
 * is child of the session so cid must be unique for all connections
 * on the session.
 **/
struct iscsi_cls_conn *
iscsi_create_conn(struct iscsi_cls_session *session, uint32_t cid)
{
        struct iscsi_transport *transport = session->transport;
        struct Scsi_Host *shost = iscsi_session_to_shost(session);
        struct iscsi_cls_conn *conn;
        int err;

        conn = kzalloc(sizeof(*conn) + transport->conndata_size, GFP_KERNEL);
        if (!conn)
                return NULL;

        if (transport->conndata_size)
                conn->dd_data = &conn[1];

        INIT_LIST_HEAD(&conn->conn_list);
        conn->transport = transport;

        /* this is released in the dev's release function */
        if (!get_device(&session->dev))
                goto free_conn;
        snprintf(conn->dev.bus_id, BUS_ID_SIZE, "connection%d:%u",
                 shost->host_no, cid);
        conn->dev.parent = &session->dev;
        conn->dev.release = iscsi_conn_release;
        err = device_register(&conn->dev);
        if (err) {
                dev_printk(KERN_ERR, &conn->dev, "iscsi: could not register "
                           "connection's dev\n");
                goto release_parent_ref;
        }
        transport_register_device(&conn->dev);
        return conn;

release_parent_ref:
        put_device(&session->dev);
free_conn:
        kfree(conn);
        return NULL;
}

EXPORT_SYMBOL_GPL(iscsi_create_conn);

/**
 * iscsi_destroy_conn - destroy iscsi class connection
 * @session: iscsi cls session
 *
 * This can be called from a LLD or iscsi_transport.
 **/
int iscsi_destroy_conn(struct iscsi_cls_conn *conn)
{
        transport_unregister_device(&conn->dev);
        device_unregister(&conn->dev);
        return 0;
}

EXPORT_SYMBOL_GPL(iscsi_destroy_conn);

/*
 * These functions are used only by software iscsi_transports
 * which do not allocate and more their scsi_hosts since this
 * is initiated from userspace.
 */

/*
 * iSCSI Session's hostdata organization:
 *
 *    *------------------* <== hostdata_session(host->hostdata)
 *    | ptr to class sess|
 *    |------------------| <== iscsi_hostdata(host->hostdata)
 *    | transport's data |
 *    *------------------*
 */

#define hostdata_privsize(_t)   (sizeof(unsigned long) + _t->hostdata_size + \
                                 _t->hostdata_size % sizeof(unsigned long))

#define hostdata_session(_hostdata) (iscsi_ptr(*(unsigned long *)_hostdata))

/**
 * iscsi_transport_create_session - create iscsi cls session and host
 * scsit: scsi transport template
 * transport: iscsi transport template
 *
 * This can be used by software iscsi_transports that allocate
 * a session per scsi host.
 **/
struct Scsi_Host *
iscsi_transport_create_session(struct scsi_transport_template *scsit,
                               struct iscsi_transport *transport)
{
        struct iscsi_cls_session *session;
        struct Scsi_Host *shost;
        unsigned long flags;

        shost = scsi_host_alloc(transport->host_template,
                                hostdata_privsize(transport));
        if (!shost) {
                printk(KERN_ERR "iscsi: can not allocate SCSI host for "
                        "session\n");
                return NULL;
        }

        shost->max_id = 1;
        shost->max_channel = 0;
        shost->max_lun = transport->max_lun;
        shost->max_cmd_len = transport->max_cmd_len;
        shost->transportt = scsit;
        shost->transportt->create_work_queue = 1;

        if (scsi_add_host(shost, NULL))
                goto free_host;

        session = iscsi_create_session(shost, transport);
        if (!session)
                goto remove_host;

        *(unsigned long*)shost->hostdata = (unsigned long)session;
        spin_lock_irqsave(&sesslock, flags);
        list_add(&session->sess_list, &sesslist);
        spin_unlock_irqrestore(&sesslock, flags);
        return shost;

remove_host:
        scsi_remove_host(shost);
free_host:
        scsi_host_put(shost);
        return NULL;
}

EXPORT_SYMBOL_GPL(iscsi_transport_create_session);

/**
 * iscsi_transport_destroy_session - destroy session and scsi host
 * shost: scsi host
 *
 * This can be used by software iscsi_transports that allocate
 * a session per scsi host.
 **/
int iscsi_transport_destroy_session(struct Scsi_Host *shost)
{
        struct iscsi_cls_session *session;
        unsigned long flags;

        scsi_remove_host(shost);
        session = hostdata_session(shost->hostdata);
        spin_lock_irqsave(&sesslock, flags);
        list_del(&session->sess_list);
        spin_unlock_irqrestore(&sesslock, flags);
        iscsi_destroy_session(session);
        /* ref from host alloc */
        scsi_host_put(shost);
        return 0;
}

EXPORT_SYMBOL_GPL(iscsi_transport_destroy_session);

/*
 * iscsi interface functions
 */
static struct iscsi_internal *
iscsi_if_transport_lookup(struct iscsi_transport *tt)
{
        struct iscsi_internal *priv;
        unsigned long flags;

        spin_lock_irqsave(&iscsi_transport_lock, flags);
        list_for_each_entry(priv, &iscsi_transports, list) {
                if (tt == priv->iscsi_transport) {
                        spin_unlock_irqrestore(&iscsi_transport_lock, flags);
                        return priv;
                }
        }
        spin_unlock_irqrestore(&iscsi_transport_lock, flags);
        return NULL;
}

static inline struct list_head *skb_to_lh(struct sk_buff *skb)
{
        return (struct list_head *)&skb->cb;
}

static void*
mempool_zone_alloc_skb(gfp_t gfp_mask, void *pool_data)
{
        struct mempool_zone *zone = pool_data;

        return alloc_skb(zone->size, gfp_mask);
}

static void
mempool_zone_free_skb(void *element, void *pool_data)
{
        kfree_skb(element);
}

static void
mempool_zone_complete(struct mempool_zone *zone)
{
        unsigned long flags;
        struct list_head *lh, *n;

        spin_lock_irqsave(&zone->freelock, flags);
        list_for_each_safe(lh, n, &zone->freequeue) {
                struct sk_buff *skb = (struct sk_buff *)((char *)lh -
                                offsetof(struct sk_buff, cb));
                if (!skb_shared(skb)) {
                        list_del(skb_to_lh(skb));
                        mempool_free(skb, zone->pool);
                        atomic_dec(&zone->allocated);
                }
        }
        spin_unlock_irqrestore(&zone->freelock, flags);
}

static struct mempool_zone *
mempool_zone_init(unsigned max, unsigned size, unsigned hiwat)
{
        struct mempool_zone *zp;

        zp = kzalloc(sizeof(*zp), GFP_KERNEL);
        if (!zp)
                return NULL;

        zp->size = size;
        zp->hiwat = hiwat;
        INIT_LIST_HEAD(&zp->freequeue);
        spin_lock_init(&zp->freelock);
        atomic_set(&zp->allocated, 0);

        zp->pool = mempool_create(max, mempool_zone_alloc_skb,
                                  mempool_zone_free_skb, zp);
        if (!zp->pool) {
                kfree(zp);
                return NULL;
        }

        return zp;
}

static void mempool_zone_destroy(struct mempool_zone *zp)
{
        mempool_destroy(zp->pool);
        kfree(zp);
}

static struct sk_buff*
mempool_zone_get_skb(struct mempool_zone *zone)
{
        struct sk_buff *skb;

        skb = mempool_alloc(zone->pool, GFP_ATOMIC);
        if (skb)
                atomic_inc(&zone->allocated);
        return skb;
}

static int
iscsi_unicast_skb(struct mempool_zone *zone, struct sk_buff *skb)
{
        unsigned long flags;
        int rc;

        skb_get(skb);
        rc = netlink_unicast(nls, skb, daemon_pid, MSG_DONTWAIT);
        if (rc < 0) {
                mempool_free(skb, zone->pool);
                printk(KERN_ERR "iscsi: can not unicast skb (%d)\n", rc);
                return rc;
        }

        spin_lock_irqsave(&zone->freelock, flags);
        list_add(skb_to_lh(skb), &zone->freequeue);
        spin_unlock_irqrestore(&zone->freelock, flags);

        return 0;
}

int iscsi_recv_pdu(struct iscsi_cls_conn *conn, struct iscsi_hdr *hdr,
                   char *data, uint32_t data_size)
{
        struct nlmsghdr *nlh;
        struct sk_buff *skb;
        struct iscsi_uevent *ev;
        char *pdu;
        int len = NLMSG_SPACE(sizeof(*ev) + sizeof(struct iscsi_hdr) +
                              data_size);

        mempool_zone_complete(conn->z_pdu);

        skb = mempool_zone_get_skb(conn->z_pdu);
        if (!skb) {
                iscsi_conn_error(conn, ISCSI_ERR_CONN_FAILED);
                dev_printk(KERN_ERR, &conn->dev, "iscsi: can not deliver "
                           "control PDU: OOM\n");
                return -ENOMEM;
        }

        nlh = __nlmsg_put(skb, daemon_pid, 0, 0, (len - sizeof(*nlh)), 0);
        ev = NLMSG_DATA(nlh);
        memset(ev, 0, sizeof(*ev));
        ev->transport_handle = iscsi_handle(conn->transport);
        ev->type = ISCSI_KEVENT_RECV_PDU;
        if (atomic_read(&conn->z_pdu->allocated) >= conn->z_pdu->hiwat)
                ev->iferror = -ENOMEM;
        ev->r.recv_req.conn_handle = iscsi_handle(conn);
        pdu = (char*)ev + sizeof(*ev);
        memcpy(pdu, hdr, sizeof(struct iscsi_hdr));
        memcpy(pdu + sizeof(struct iscsi_hdr), data, data_size);

        return iscsi_unicast_skb(conn->z_pdu, skb);
}
EXPORT_SYMBOL_GPL(iscsi_recv_pdu);

void iscsi_conn_error(struct iscsi_cls_conn *conn, enum iscsi_err error)
{
        struct nlmsghdr *nlh;
        struct sk_buff  *skb;
        struct iscsi_uevent *ev;
        int len = NLMSG_SPACE(sizeof(*ev));

        mempool_zone_complete(conn->z_error);

        skb = mempool_zone_get_skb(conn->z_error);
        if (!skb) {
                dev_printk(KERN_ERR, &conn->dev, "iscsi: gracefully ignored "
                          "conn error (%d)\n", error);
                return;
        }

        nlh = __nlmsg_put(skb, daemon_pid, 0, 0, (len - sizeof(*nlh)), 0);
        ev = NLMSG_DATA(nlh);
        ev->transport_handle = iscsi_handle(conn->transport);
        ev->type = ISCSI_KEVENT_CONN_ERROR;
        if (atomic_read(&conn->z_error->allocated) >= conn->z_error->hiwat)
                ev->iferror = -ENOMEM;
        ev->r.connerror.error = error;
        ev->r.connerror.conn_handle = iscsi_handle(conn);

        iscsi_unicast_skb(conn->z_error, skb);

        dev_printk(KERN_INFO, &conn->dev, "iscsi: detected conn error (%d)\n",
                   error);
}
EXPORT_SYMBOL_GPL(iscsi_conn_error);

static int
iscsi_if_send_reply(int pid, int seq, int type, int done, int multi,
                      void *payload, int size)
{
        struct sk_buff  *skb;
        struct nlmsghdr *nlh;
        int len = NLMSG_SPACE(size);
        int flags = multi ? NLM_F_MULTI : 0;
        int t = done ? NLMSG_DONE : type;

        mempool_zone_complete(z_reply);

        skb = mempool_zone_get_skb(z_reply);
        /*
         * FIXME:
         * user is supposed to react on iferror == -ENOMEM;
         * see iscsi_if_rx().
         */
        BUG_ON(!skb);

        nlh = __nlmsg_put(skb, pid, seq, t, (len - sizeof(*nlh)), 0);
        nlh->nlmsg_flags = flags;
        memcpy(NLMSG_DATA(nlh), payload, size);
        return iscsi_unicast_skb(z_reply, skb);
}

static int
iscsi_if_get_stats(struct iscsi_transport *transport, struct nlmsghdr *nlh)
{
        struct iscsi_uevent *ev = NLMSG_DATA(nlh);
        struct iscsi_stats *stats;
        struct sk_buff *skbstat;
        struct iscsi_cls_conn *conn;
        struct nlmsghdr *nlhstat;
        struct iscsi_uevent *evstat;
        int len = NLMSG_SPACE(sizeof(*ev) +
                              sizeof(struct iscsi_stats) +
                              sizeof(struct iscsi_stats_custom) *
                              ISCSI_STATS_CUSTOM_MAX);
        int err = 0;

        conn = iscsi_conn_lookup(ev->u.get_stats.conn_handle);
        if (!conn)
                return -EEXIST;

        do {
                int actual_size;

                mempool_zone_complete(conn->z_pdu);

                skbstat = mempool_zone_get_skb(conn->z_pdu);
                if (!skbstat) {
                        dev_printk(KERN_ERR, &conn->dev, "iscsi: can not "
                                   "deliver stats: OOM\n");
                        return -ENOMEM;
                }

                nlhstat = __nlmsg_put(skbstat, daemon_pid, 0, 0,
                                      (len - sizeof(*nlhstat)), 0);
                evstat = NLMSG_DATA(nlhstat);
                memset(evstat, 0, sizeof(*evstat));
                evstat->transport_handle = iscsi_handle(conn->transport);
                evstat->type = nlh->nlmsg_type;
                if (atomic_read(&conn->z_pdu->allocated) >= conn->z_pdu->hiwat)
                        evstat->iferror = -ENOMEM;
                evstat->u.get_stats.conn_handle =
                        ev->u.get_stats.conn_handle;
                stats = (struct iscsi_stats *)
                        ((char*)evstat + sizeof(*evstat));
                memset(stats, 0, sizeof(*stats));

                transport->get_stats(conn, stats);
                actual_size = NLMSG_SPACE(sizeof(struct iscsi_uevent) +
                                          sizeof(struct iscsi_stats) +
                                          sizeof(struct iscsi_stats_custom) *
                                          stats->custom_length);
                actual_size -= sizeof(*nlhstat);
                actual_size = NLMSG_LENGTH(actual_size);
                skb_trim(skbstat, NLMSG_ALIGN(actual_size));
                nlhstat->nlmsg_len = actual_size;

                err = iscsi_unicast_skb(conn->z_pdu, skbstat);
        } while (err < 0 && err != -ECONNREFUSED);

        return err;
}

static int
iscsi_if_create_session(struct iscsi_internal *priv, struct iscsi_uevent *ev)
{
        struct iscsi_transport *transport = priv->iscsi_transport;
        struct iscsi_cls_session *session;
        uint32_t sid;

        session = transport->create_session(&priv->t,
                                            ev->u.c_session.initial_cmdsn,
                                            &sid);
        if (!session)
                return -ENOMEM;

        ev->r.c_session_ret.session_handle = iscsi_handle(session);
        ev->r.c_session_ret.sid = sid;
        return 0;
}

static int
iscsi_if_create_conn(struct iscsi_transport *transport, struct iscsi_uevent *ev)
{
        struct iscsi_cls_conn *conn;
        struct iscsi_cls_session *session;
        unsigned long flags;

        session = iscsi_session_lookup(ev->u.c_conn.session_handle);
        if (!session)
                return -EINVAL;

        conn = transport->create_conn(session, ev->u.c_conn.cid);
        if (!conn)
                return -ENOMEM;

        conn->z_pdu = mempool_zone_init(Z_MAX_PDU,
                        NLMSG_SPACE(sizeof(struct iscsi_uevent) +
                                    sizeof(struct iscsi_hdr) +
                                    DEFAULT_MAX_RECV_DATA_SEGMENT_LENGTH),
                        Z_HIWAT_PDU);
        if (!conn->z_pdu) {
                dev_printk(KERN_ERR, &conn->dev, "iscsi: can not allocate "
                           "pdu zone for new conn\n");
                goto destroy_conn;
        }

        conn->z_error = mempool_zone_init(Z_MAX_ERROR,
                        NLMSG_SPACE(sizeof(struct iscsi_uevent)),
                        Z_HIWAT_ERROR);
        if (!conn->z_error) {
                dev_printk(KERN_ERR, &conn->dev, "iscsi: can not allocate "
                           "error zone for new conn\n");
                goto free_pdu_pool;
        }

        ev->r.handle = iscsi_handle(conn);

        spin_lock_irqsave(&connlock, flags);
        list_add(&conn->conn_list, &connlist);
        conn->active = 1;
        spin_unlock_irqrestore(&connlock, flags);

        return 0;

free_pdu_pool:
        mempool_zone_destroy(conn->z_pdu);
destroy_conn:
        if (transport->destroy_conn)
                transport->destroy_conn(conn->dd_data);
        return -ENOMEM;
}

static int
iscsi_if_destroy_conn(struct iscsi_transport *transport, struct iscsi_uevent *ev)
{
        unsigned long flags;
        struct iscsi_cls_conn *conn;
        struct mempool_zone *z_error, *z_pdu;

        conn = iscsi_conn_lookup(ev->u.d_conn.conn_handle);
        if (!conn)
                return -EINVAL;
        spin_lock_irqsave(&connlock, flags);
        conn->active = 0;
        list_del(&conn->conn_list);
        spin_unlock_irqrestore(&connlock, flags);

        z_pdu = conn->z_pdu;
        z_error = conn->z_error;

        if (transport->destroy_conn)
                transport->destroy_conn(conn);

        mempool_zone_destroy(z_pdu);
        mempool_zone_destroy(z_error);

        return 0;
}

static int
iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
        int err = 0;
        struct iscsi_uevent *ev = NLMSG_DATA(nlh);
        struct iscsi_transport *transport = NULL;
        struct iscsi_internal *priv;
        struct iscsi_cls_session *session;
        struct iscsi_cls_conn *conn;

        priv = iscsi_if_transport_lookup(iscsi_ptr(ev->transport_handle));
        if (!priv)
                return -EINVAL;
        transport = priv->iscsi_transport;

        if (!try_module_get(transport->owner))
                return -EINVAL;

        switch (nlh->nlmsg_type) {
        case ISCSI_UEVENT_CREATE_SESSION:
                err = iscsi_if_create_session(priv, ev);
                break;
        case ISCSI_UEVENT_DESTROY_SESSION:
                session = iscsi_session_lookup(ev->u.d_session.session_handle);
                if (session)
                        transport->destroy_session(session);
                else
                        err = -EINVAL;
                break;
        case ISCSI_UEVENT_CREATE_CONN:
                err = iscsi_if_create_conn(transport, ev);
                break;
        case ISCSI_UEVENT_DESTROY_CONN:
                err = iscsi_if_destroy_conn(transport, ev);
                break;
        case ISCSI_UEVENT_BIND_CONN:
                session = iscsi_session_lookup(ev->u.b_conn.session_handle);
                conn = iscsi_conn_lookup(ev->u.b_conn.conn_handle);

                if (session && conn)
                        ev->r.retcode = transport->bind_conn(session, conn,
                                        ev->u.b_conn.transport_fd,
                                        ev->u.b_conn.is_leading);
                else
                        err = -EINVAL;
                break;
        case ISCSI_UEVENT_SET_PARAM:
                conn = iscsi_conn_lookup(ev->u.set_param.conn_handle);
                if (conn)
                        ev->r.retcode = transport->set_param(conn,
                                ev->u.set_param.param, ev->u.set_param.value);
                else
                        err = -EINVAL;
                break;
        case ISCSI_UEVENT_START_CONN:
                conn = iscsi_conn_lookup(ev->u.start_conn.conn_handle);
                if (conn)
                        ev->r.retcode = transport->start_conn(conn);
                else
                        err = -EINVAL;

                break;
        case ISCSI_UEVENT_STOP_CONN:
                conn = iscsi_conn_lookup(ev->u.stop_conn.conn_handle);
                if (conn)
                        transport->stop_conn(conn, ev->u.stop_conn.flag);
                else
                        err = -EINVAL;
                break;
        case ISCSI_UEVENT_SEND_PDU:
                conn = iscsi_conn_lookup(ev->u.send_pdu.conn_handle);
                if (conn)
                        ev->r.retcode = transport->send_pdu(conn,
                                (struct iscsi_hdr*)((char*)ev + sizeof(*ev)),
                                (char*)ev + sizeof(*ev) + ev->u.send_pdu.hdr_size,
                                ev->u.send_pdu.data_size);
                else
                        err = -EINVAL;
                break;
        case ISCSI_UEVENT_GET_STATS:
                err = iscsi_if_get_stats(transport, nlh);
                break;
        default:
                err = -EINVAL;
                break;
        }

        module_put(transport->owner);
        return err;
}

/* Get message from skb (based on rtnetlink_rcv_skb).  Each message is
 * processed by iscsi_if_recv_msg.  Malformed skbs with wrong length are
 * or invalid creds discarded silently.  */
static void
iscsi_if_rx(struct sock *sk, int len)
{
        struct sk_buff *skb;

        mutex_lock(&rx_queue_mutex);
        while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
                if (NETLINK_CREDS(skb)->uid) {
                        skb_pull(skb, skb->len);
                        goto free_skb;
                }
                daemon_pid = NETLINK_CREDS(skb)->pid;

                while (skb->len >= NLMSG_SPACE(0)) {
                        int err;
                        uint32_t rlen;
                        struct nlmsghdr *nlh;
                        struct iscsi_uevent *ev;

                        nlh = (struct nlmsghdr *)skb->data;
                        if (nlh->nlmsg_len < sizeof(*nlh) ||
                            skb->len < nlh->nlmsg_len) {
                                break;
                        }

                        ev = NLMSG_DATA(nlh);
                        rlen = NLMSG_ALIGN(nlh->nlmsg_len);
                        if (rlen > skb->len)
                                rlen = skb->len;

                        err = iscsi_if_recv_msg(skb, nlh);
                        if (err) {
                                ev->type = ISCSI_KEVENT_IF_ERROR;
                                ev->iferror = err;
                        }
                        do {
                                /*
                                 * special case for GET_STATS:
                                 * on success - sending reply and stats from
                                 * inside of if_recv_msg(),
                                 * on error - fall through.
                                 */
                                if (ev->type == ISCSI_UEVENT_GET_STATS && !err)
                                        break;
                                err = iscsi_if_send_reply(
                                        NETLINK_CREDS(skb)->pid, nlh->nlmsg_seq,
                                        nlh->nlmsg_type, 0, 0, ev, sizeof(*ev));
                                if (atomic_read(&z_reply->allocated) >=
                                                z_reply->hiwat)
                                        ev->iferror = -ENOMEM;
                        } while (err < 0 && err != -ECONNREFUSED);
                        skb_pull(skb, rlen);
                }
free_skb:
                kfree_skb(skb);
        }
        mutex_unlock(&rx_queue_mutex);
}

#define iscsi_cdev_to_conn(_cdev) \
        iscsi_dev_to_conn(_cdev->dev)

/*
 * iSCSI connection attrs
 */
#define iscsi_conn_int_attr_show(param, format)                         \
static ssize_t                                                          \
show_conn_int_param_##param(struct class_device *cdev, char *buf)       \
{                                                                       \
        uint32_t value = 0;                                             \
        struct iscsi_cls_conn *conn = iscsi_cdev_to_conn(cdev);         \
        struct iscsi_transport *t = conn->transport;                    \
                                                                        \
        t->get_conn_param(conn, param, &value);                         \
        return snprintf(buf, 20, format"\n", value);                    \
}

#define iscsi_conn_int_attr(field, param, format)                       \
        iscsi_conn_int_attr_show(param, format)                         \
static CLASS_DEVICE_ATTR(field, S_IRUGO, show_conn_int_param_##param, NULL);

iscsi_conn_int_attr(max_recv_dlength, ISCSI_PARAM_MAX_RECV_DLENGTH, "%u");
iscsi_conn_int_attr(max_xmit_dlength, ISCSI_PARAM_MAX_XMIT_DLENGTH, "%u");
iscsi_conn_int_attr(header_digest, ISCSI_PARAM_HDRDGST_EN, "%d");
iscsi_conn_int_attr(data_digest, ISCSI_PARAM_DATADGST_EN, "%d");
iscsi_conn_int_attr(ifmarker, ISCSI_PARAM_IFMARKER_EN, "%d");
iscsi_conn_int_attr(ofmarker, ISCSI_PARAM_OFMARKER_EN, "%d");

#define iscsi_cdev_to_session(_cdev) \
        iscsi_dev_to_session(_cdev->dev)

/*
 * iSCSI session attrs
 */
#define iscsi_session_int_attr_show(param, format)                      \
static ssize_t                                                          \
show_session_int_param_##param(struct class_device *cdev, char *buf)    \
{                                                                       \
        uint32_t value = 0;                                             \
        struct iscsi_cls_session *session = iscsi_cdev_to_session(cdev);        \
        struct iscsi_transport *t = session->transport;                 \
                                                                        \
        t->get_session_param(session, param, &value);                   \
        return snprintf(buf, 20, format"\n", value);                    \
}

#define iscsi_session_int_attr(field, param, format)                    \
        iscsi_session_int_attr_show(param, format)                      \
static CLASS_DEVICE_ATTR(field, S_IRUGO, show_session_int_param_##param, NULL);

iscsi_session_int_attr(initial_r2t, ISCSI_PARAM_INITIAL_R2T_EN, "%d");
iscsi_session_int_attr(max_outstanding_r2t, ISCSI_PARAM_MAX_R2T, "%hu");
iscsi_session_int_attr(immediate_data, ISCSI_PARAM_IMM_DATA_EN, "%d");
iscsi_session_int_attr(first_burst_len, ISCSI_PARAM_FIRST_BURST, "%u");
iscsi_session_int_attr(max_burst_len, ISCSI_PARAM_MAX_BURST, "%u");
iscsi_session_int_attr(data_pdu_in_order, ISCSI_PARAM_PDU_INORDER_EN, "%d");
iscsi_session_int_attr(data_seq_in_order, ISCSI_PARAM_DATASEQ_INORDER_EN, "%d");
iscsi_session_int_attr(erl, ISCSI_PARAM_ERL, "%d");

#define SETUP_SESSION_RD_ATTR(field, param)                             \
        if (priv->param_mask & (1 << param)) {                          \
                priv->session_attrs[count] = &class_device_attr_##field;\
                count++;                                                \
        }

#define SETUP_CONN_RD_ATTR(field, param)                                \
        if (priv->param_mask & (1 << param)) {                          \
                priv->conn_attrs[count] = &class_device_attr_##field;   \
                count++;                                                \
        }

static int iscsi_session_match(struct attribute_container *cont,
                           struct device *dev)
{
        struct iscsi_cls_session *session;
        struct Scsi_Host *shost;
        struct iscsi_internal *priv;

        if (!iscsi_is_session_dev(dev))
                return 0;

        session = iscsi_dev_to_session(dev);
        shost = iscsi_session_to_shost(session);
        if (!shost->transportt)
                return 0;

        priv = to_iscsi_internal(shost->transportt);
        if (priv->session_cont.ac.class != &iscsi_session_class.class)
                return 0;

        return &priv->session_cont.ac == cont;
}

static int iscsi_conn_match(struct attribute_container *cont,
                           struct device *dev)
{
        struct iscsi_cls_session *session;
        struct iscsi_cls_conn *conn;
        struct Scsi_Host *shost;
        struct iscsi_internal *priv;

        if (!iscsi_is_conn_dev(dev))
                return 0;

        conn = iscsi_dev_to_conn(dev);
        session = iscsi_dev_to_session(conn->dev.parent);
        shost = iscsi_session_to_shost(session);

        if (!shost->transportt)
                return 0;

        priv = to_iscsi_internal(shost->transportt);
        if (priv->conn_cont.ac.class != &iscsi_connection_class.class)
                return 0;

        return &priv->conn_cont.ac == cont;
}

struct scsi_transport_template *
iscsi_register_transport(struct iscsi_transport *tt)
{
        struct iscsi_internal *priv;
        unsigned long flags;
        int count = 0, err;

        BUG_ON(!tt);

        priv = iscsi_if_transport_lookup(tt);
        if (priv)
                return NULL;

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return NULL;
        INIT_LIST_HEAD(&priv->list);
        priv->iscsi_transport = tt;

        priv->cdev.class = &iscsi_transport_class;
        snprintf(priv->cdev.class_id, BUS_ID_SIZE, "%s", tt->name);
        err = class_device_register(&priv->cdev);
        if (err)
                goto free_priv;

        err = sysfs_create_group(&priv->cdev.kobj, &iscsi_transport_group);
        if (err)
                goto unregister_cdev;

        /* setup parameters mask */
        priv->param_mask = 0xFFFFFFFF;
        if (!(tt->caps & CAP_MULTI_R2T))
                priv->param_mask &= ~(1 << ISCSI_PARAM_MAX_R2T);
        if (!(tt->caps & CAP_HDRDGST))
                priv->param_mask &= ~(1 << ISCSI_PARAM_HDRDGST_EN);
        if (!(tt->caps & CAP_DATADGST))
                priv->param_mask &= ~(1 << ISCSI_PARAM_DATADGST_EN);
        if (!(tt->caps & CAP_MARKERS)) {
                priv->param_mask &= ~(1 << ISCSI_PARAM_IFMARKER_EN);
                priv->param_mask &= ~(1 << ISCSI_PARAM_OFMARKER_EN);
        }

        /* connection parameters */
        priv->conn_cont.ac.attrs = &priv->conn_attrs[0];
        priv->conn_cont.ac.class = &iscsi_connection_class.class;
        priv->conn_cont.ac.match = iscsi_conn_match;
        transport_container_register(&priv->conn_cont);

        SETUP_CONN_RD_ATTR(max_recv_dlength, ISCSI_PARAM_MAX_RECV_DLENGTH);
        SETUP_CONN_RD_ATTR(max_xmit_dlength, ISCSI_PARAM_MAX_XMIT_DLENGTH);
        SETUP_CONN_RD_ATTR(header_digest, ISCSI_PARAM_HDRDGST_EN);
        SETUP_CONN_RD_ATTR(data_digest, ISCSI_PARAM_DATADGST_EN);
        SETUP_CONN_RD_ATTR(ifmarker, ISCSI_PARAM_IFMARKER_EN);
        SETUP_CONN_RD_ATTR(ofmarker, ISCSI_PARAM_OFMARKER_EN);

        BUG_ON(count > ISCSI_CONN_ATTRS);
        priv->conn_attrs[count] = NULL;
        count = 0;

        /* session parameters */
        priv->session_cont.ac.attrs = &priv->session_attrs[0];
        priv->session_cont.ac.class = &iscsi_session_class.class;
        priv->session_cont.ac.match = iscsi_session_match;
        transport_container_register(&priv->session_cont);

        SETUP_SESSION_RD_ATTR(initial_r2t, ISCSI_PARAM_INITIAL_R2T_EN);
        SETUP_SESSION_RD_ATTR(max_outstanding_r2t, ISCSI_PARAM_MAX_R2T);
        SETUP_SESSION_RD_ATTR(immediate_data, ISCSI_PARAM_IMM_DATA_EN);
        SETUP_SESSION_RD_ATTR(first_burst_len, ISCSI_PARAM_FIRST_BURST);
        SETUP_SESSION_RD_ATTR(max_burst_len, ISCSI_PARAM_MAX_BURST);
        SETUP_SESSION_RD_ATTR(data_pdu_in_order, ISCSI_PARAM_PDU_INORDER_EN);
        SETUP_SESSION_RD_ATTR(data_seq_in_order,ISCSI_PARAM_DATASEQ_INORDER_EN)
        SETUP_SESSION_RD_ATTR(erl, ISCSI_PARAM_ERL);

        BUG_ON(count > ISCSI_SESSION_ATTRS);
        priv->session_attrs[count] = NULL;

        spin_lock_irqsave(&iscsi_transport_lock, flags);
        list_add(&priv->list, &iscsi_transports);
        spin_unlock_irqrestore(&iscsi_transport_lock, flags);

        printk(KERN_NOTICE "iscsi: registered transport (%s)\n", tt->name);
        return &priv->t;

unregister_cdev:
        class_device_unregister(&priv->cdev);
free_priv:
        kfree(priv);
        return NULL;
}
EXPORT_SYMBOL_GPL(iscsi_register_transport);

int iscsi_unregister_transport(struct iscsi_transport *tt)
{
        struct iscsi_internal *priv;
        unsigned long flags;

        BUG_ON(!tt);

        mutex_lock(&rx_queue_mutex);

        priv = iscsi_if_transport_lookup(tt);
        BUG_ON (!priv);

        spin_lock_irqsave(&iscsi_transport_lock, flags);
        list_del(&priv->list);
        spin_unlock_irqrestore(&iscsi_transport_lock, flags);

        transport_container_unregister(&priv->conn_cont);
        transport_container_unregister(&priv->session_cont);

        sysfs_remove_group(&priv->cdev.kobj, &iscsi_transport_group);
        class_device_unregister(&priv->cdev);
        mutex_unlock(&rx_queue_mutex);

        return 0;
}
EXPORT_SYMBOL_GPL(iscsi_unregister_transport);

static int
iscsi_rcv_nl_event(struct notifier_block *this, unsigned long event, void *ptr)
{
        struct netlink_notify *n = ptr;

        if (event == NETLINK_URELEASE &&
            n->protocol == NETLINK_ISCSI && n->pid) {
                struct iscsi_cls_conn *conn;
                unsigned long flags;

                mempool_zone_complete(z_reply);
                spin_lock_irqsave(&connlock, flags);
                list_for_each_entry(conn, &connlist, conn_list) {
                        mempool_zone_complete(conn->z_error);
                        mempool_zone_complete(conn->z_pdu);
                }
                spin_unlock_irqrestore(&connlock, flags);
        }

        return NOTIFY_DONE;
}

static struct notifier_block iscsi_nl_notifier = {
        .notifier_call  = iscsi_rcv_nl_event,
};

static __init int iscsi_transport_init(void)
{
        int err;

        err = class_register(&iscsi_transport_class);
        if (err)
                return err;

        err = transport_class_register(&iscsi_connection_class);
        if (err)
                goto unregister_transport_class;

        err = transport_class_register(&iscsi_session_class);
        if (err)
                goto unregister_conn_class;

        err = netlink_register_notifier(&iscsi_nl_notifier);
        if (err)
                goto unregister_session_class;

        nls = netlink_kernel_create(NETLINK_ISCSI, 1, iscsi_if_rx,
                        THIS_MODULE);
        if (!nls) {
                err = -ENOBUFS;
                goto unregister_notifier;
        }

        z_reply = mempool_zone_init(Z_MAX_REPLY,
                NLMSG_SPACE(sizeof(struct iscsi_uevent)), Z_HIWAT_REPLY);
        if (z_reply)
                return 0;

        sock_release(nls->sk_socket);
unregister_notifier:
        netlink_unregister_notifier(&iscsi_nl_notifier);
unregister_session_class:
        transport_class_unregister(&iscsi_session_class);
unregister_conn_class:
        transport_class_unregister(&iscsi_connection_class);
unregister_transport_class:
        class_unregister(&iscsi_transport_class);
        return err;
}

static void __exit iscsi_transport_exit(void)
{
        mempool_zone_destroy(z_reply);
        sock_release(nls->sk_socket);
        netlink_unregister_notifier(&iscsi_nl_notifier);
        transport_class_unregister(&iscsi_connection_class);
        transport_class_unregister(&iscsi_session_class);
        class_unregister(&iscsi_transport_class);
}

module_init(iscsi_transport_init);
module_exit(iscsi_transport_exit);

MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
              "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
              "Alex Aizman <itn780@yahoo.com>");
MODULE_DESCRIPTION("iSCSI Transport Interface");
MODULE_LICENSE("GPL");