/*
 * Copyright (c) 2005 Cisco Systems.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#define pr_fmt(fmt) PFX fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/parser.h>
#include <linux/random.h>
#include <linux/jiffies.h>

#include <linux/atomic.h>

#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_dbg.h>
#include <scsi/srp.h>
#include <scsi/scsi_transport_srp.h>

#include "ib_srp.h"

#define DRV_NAME        "ib_srp"
#define PFX             DRV_NAME ": "
#define DRV_VERSION     "1.0"
#define DRV_RELDATE     "July 1, 2013"

MODULE_AUTHOR("Roland Dreier");
MODULE_DESCRIPTION("InfiniBand SCSI RDMA Protocol initiator "
                   "v" DRV_VERSION " (" DRV_RELDATE ")");
MODULE_LICENSE("Dual BSD/GPL");

static unsigned int srp_sg_tablesize;
static unsigned int cmd_sg_entries;
static unsigned int indirect_sg_entries;
static bool allow_ext_sg;
static int topspin_workarounds = 1;

module_param(srp_sg_tablesize, uint, 0444);
MODULE_PARM_DESC(srp_sg_tablesize, "Deprecated name for cmd_sg_entries");

module_param(cmd_sg_entries, uint, 0444);
MODULE_PARM_DESC(cmd_sg_entries,
                 "Default number of gather/scatter entries in the SRP command (default is 12, max 255)");

module_param(indirect_sg_entries, uint, 0444);
MODULE_PARM_DESC(indirect_sg_entries,
                 "Default max number of gather/scatter entries (default is 12, max is " __stringify(SCSI_MAX_SG_CHAIN_SEGMENTS) ")");

module_param(allow_ext_sg, bool, 0444);
MODULE_PARM_DESC(allow_ext_sg,
                  "Default behavior when there are more than cmd_sg_entries S/G entries after mapping; fails the request when false (default false)");

module_param(topspin_workarounds, int, 0444);
MODULE_PARM_DESC(topspin_workarounds,
                 "Enable workarounds for Topspin/Cisco SRP target bugs if != 0");

static void srp_add_one(struct ib_device *device);
static void srp_remove_one(struct ib_device *device);
static void srp_recv_completion(struct ib_cq *cq, void *target_ptr);
static void srp_send_completion(struct ib_cq *cq, void *target_ptr);
static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event);

static struct scsi_transport_template *ib_srp_transport_template;

static struct ib_client srp_client = {
        .name   = "srp",
        .add    = srp_add_one,
        .remove = srp_remove_one
};

static struct ib_sa_client srp_sa_client;

static inline struct srp_target_port *host_to_target(struct Scsi_Host *host)
{
        return (struct srp_target_port *) host->hostdata;
}

static const char *srp_target_info(struct Scsi_Host *host)
{
        return host_to_target(host)->target_name;
}

static int srp_target_is_topspin(struct srp_target_port *target)
{
        static const u8 topspin_oui[3] = { 0x00, 0x05, 0xad };
        static const u8 cisco_oui[3]   = { 0x00, 0x1b, 0x0d };

        return topspin_workarounds &&
                (!memcmp(&target->ioc_guid, topspin_oui, sizeof topspin_oui) ||
                 !memcmp(&target->ioc_guid, cisco_oui, sizeof cisco_oui));
}

static struct srp_iu *srp_alloc_iu(struct srp_host *host, size_t size,
                                   gfp_t gfp_mask,
                                   enum dma_data_direction direction)
{
        struct srp_iu *iu;

        iu = kmalloc(sizeof *iu, gfp_mask);
        if (!iu)
                goto out;

        iu->buf = kzalloc(size, gfp_mask);
        if (!iu->buf)
                goto out_free_iu;

        iu->dma = ib_dma_map_single(host->srp_dev->dev, iu->buf, size,
                                    direction);
        if (ib_dma_mapping_error(host->srp_dev->dev, iu->dma))
                goto out_free_buf;

        iu->size      = size;
        iu->direction = direction;

        return iu;

out_free_buf:
        kfree(iu->buf);
out_free_iu:
        kfree(iu);
out:
        return NULL;
}

static void srp_free_iu(struct srp_host *host, struct srp_iu *iu)
{
        if (!iu)
                return;

        ib_dma_unmap_single(host->srp_dev->dev, iu->dma, iu->size,
                            iu->direction);
        kfree(iu->buf);
        kfree(iu);
}

static void srp_qp_event(struct ib_event *event, void *context)
{
        pr_debug("QP event %d\n", event->event);
}

static int srp_init_qp(struct srp_target_port *target,
                       struct ib_qp *qp)
{
        struct ib_qp_attr *attr;
        int ret;

        attr = kmalloc(sizeof *attr, GFP_KERNEL);
        if (!attr)
                return -ENOMEM;

        ret = ib_find_pkey(target->srp_host->srp_dev->dev,
                           target->srp_host->port,
                           be16_to_cpu(target->path.pkey),
                           &attr->pkey_index);
        if (ret)
                goto out;

        attr->qp_state        = IB_QPS_INIT;
        attr->qp_access_flags = (IB_ACCESS_REMOTE_READ |
                                    IB_ACCESS_REMOTE_WRITE);
        attr->port_num        = target->srp_host->port;

        ret = ib_modify_qp(qp, attr,
                           IB_QP_STATE          |
                           IB_QP_PKEY_INDEX     |
                           IB_QP_ACCESS_FLAGS   |
                           IB_QP_PORT);

out:
        kfree(attr);
        return ret;
}

static int srp_new_cm_id(struct srp_target_port *target)
{
        struct ib_cm_id *new_cm_id;

        new_cm_id = ib_create_cm_id(target->srp_host->srp_dev->dev,
                                    srp_cm_handler, target);
        if (IS_ERR(new_cm_id))
                return PTR_ERR(new_cm_id);

        if (target->cm_id)
                ib_destroy_cm_id(target->cm_id);
        target->cm_id = new_cm_id;

        return 0;
}

static int srp_create_target_ib(struct srp_target_port *target)
{
        struct ib_qp_init_attr *init_attr;
        struct ib_cq *recv_cq, *send_cq;
        struct ib_qp *qp;
        int ret;

        init_attr = kzalloc(sizeof *init_attr, GFP_KERNEL);
        if (!init_attr)
                return -ENOMEM;

        recv_cq = ib_create_cq(target->srp_host->srp_dev->dev,
                               srp_recv_completion, NULL, target, SRP_RQ_SIZE,
                               target->comp_vector);
        if (IS_ERR(recv_cq)) {
                ret = PTR_ERR(recv_cq);
                goto err;
        }

        send_cq = ib_create_cq(target->srp_host->srp_dev->dev,
                               srp_send_completion, NULL, target, SRP_SQ_SIZE,
                               target->comp_vector);
        if (IS_ERR(send_cq)) {
                ret = PTR_ERR(send_cq);
                goto err_recv_cq;
        }

        ib_req_notify_cq(recv_cq, IB_CQ_NEXT_COMP);

        init_attr->event_handler       = srp_qp_event;
        init_attr->cap.max_send_wr     = SRP_SQ_SIZE;
        init_attr->cap.max_recv_wr     = SRP_RQ_SIZE;
        init_attr->cap.max_recv_sge    = 1;
        init_attr->cap.max_send_sge    = 1;
        init_attr->sq_sig_type         = IB_SIGNAL_ALL_WR;
        init_attr->qp_type             = IB_QPT_RC;
        init_attr->send_cq             = send_cq;
        init_attr->recv_cq             = recv_cq;

        qp = ib_create_qp(target->srp_host->srp_dev->pd, init_attr);
        if (IS_ERR(qp)) {
                ret = PTR_ERR(qp);
                goto err_send_cq;
        }

        ret = srp_init_qp(target, qp);
        if (ret)
                goto err_qp;

        if (target->qp)
                ib_destroy_qp(target->qp);
        if (target->recv_cq)
                ib_destroy_cq(target->recv_cq);
        if (target->send_cq)
                ib_destroy_cq(target->send_cq);

        target->qp = qp;
        target->recv_cq = recv_cq;
        target->send_cq = send_cq;

        kfree(init_attr);
        return 0;

err_qp:
        ib_destroy_qp(qp);

err_send_cq:
        ib_destroy_cq(send_cq);

err_recv_cq:
        ib_destroy_cq(recv_cq);

err:
        kfree(init_attr);
        return ret;
}

static void srp_free_target_ib(struct srp_target_port *target)
{
        int i;

        ib_destroy_qp(target->qp);
        ib_destroy_cq(target->send_cq);
        ib_destroy_cq(target->recv_cq);

        target->qp = NULL;
        target->send_cq = target->recv_cq = NULL;

        for (i = 0; i < SRP_RQ_SIZE; ++i)
                srp_free_iu(target->srp_host, target->rx_ring[i]);
        for (i = 0; i < SRP_SQ_SIZE; ++i)
                srp_free_iu(target->srp_host, target->tx_ring[i]);
}

static void srp_path_rec_completion(int status,
                                    struct ib_sa_path_rec *pathrec,
                                    void *target_ptr)
{
        struct srp_target_port *target = target_ptr;

        target->status = status;
        if (status)
                shost_printk(KERN_ERR, target->scsi_host,
                             PFX "Got failed path rec status %d\n", status);
        else
                target->path = *pathrec;
        complete(&target->done);
}

static int srp_lookup_path(struct srp_target_port *target)
{
        target->path.numb_path = 1;

        init_completion(&target->done);

        target->path_query_id = ib_sa_path_rec_get(&srp_sa_client,
                                                   target->srp_host->srp_dev->dev,
                                                   target->srp_host->port,
                                                   &target->path,
                                                   IB_SA_PATH_REC_SERVICE_ID    |
                                                   IB_SA_PATH_REC_DGID          |
                                                   IB_SA_PATH_REC_SGID          |
                                                   IB_SA_PATH_REC_NUMB_PATH     |
                                                   IB_SA_PATH_REC_PKEY,
                                                   SRP_PATH_REC_TIMEOUT_MS,
                                                   GFP_KERNEL,
                                                   srp_path_rec_completion,
                                                   target, &target->path_query);
        if (target->path_query_id < 0)
                return target->path_query_id;

        wait_for_completion(&target->done);

        if (target->status < 0)
                shost_printk(KERN_WARNING, target->scsi_host,
                             PFX "Path record query failed\n");

        return target->status;
}

static int srp_send_req(struct srp_target_port *target)
{
        struct {
                struct ib_cm_req_param param;
                struct srp_login_req   priv;
        } *req = NULL;
        int status;

        req = kzalloc(sizeof *req, GFP_KERNEL);
        if (!req)
                return -ENOMEM;

        req->param.primary_path               = &target->path;
        req->param.alternate_path             = NULL;
        req->param.service_id                 = target->service_id;
        req->param.qp_num                     = target->qp->qp_num;
        req->param.qp_type                    = target->qp->qp_type;
        req->param.private_data               = &req->priv;
        req->param.private_data_len           = sizeof req->priv;
        req->param.flow_control               = 1;

        get_random_bytes(&req->param.starting_psn, 4);
        req->param.starting_psn              &= 0xffffff;

        /*
         * Pick some arbitrary defaults here; we could make these
         * module parameters if anyone cared about setting them.
         */
        req->param.responder_resources        = 4;
        req->param.remote_cm_response_timeout = 20;
        req->param.local_cm_response_timeout  = 20;
        req->param.retry_count                = 7;
        req->param.rnr_retry_count            = 7;
        req->param.max_cm_retries             = 15;

        req->priv.opcode        = SRP_LOGIN_REQ;
        req->priv.tag           = 0;
        req->priv.req_it_iu_len = cpu_to_be32(target->max_iu_len);
        req->priv.req_buf_fmt   = cpu_to_be16(SRP_BUF_FORMAT_DIRECT |
                                              SRP_BUF_FORMAT_INDIRECT);
        /*
         * In the published SRP specification (draft rev. 16a), the
         * port identifier format is 8 bytes of ID extension followed
         * by 8 bytes of GUID.  Older drafts put the two halves in the
         * opposite order, so that the GUID comes first.
         *
         * Targets conforming to these obsolete drafts can be
         * recognized by the I/O Class they report.
         */
        if (target->io_class == SRP_REV10_IB_IO_CLASS) {
                memcpy(req->priv.initiator_port_id,
                       &target->path.sgid.global.interface_id, 8);
                memcpy(req->priv.initiator_port_id + 8,
                       &target->initiator_ext, 8);
                memcpy(req->priv.target_port_id,     &target->ioc_guid, 8);
                memcpy(req->priv.target_port_id + 8, &target->id_ext, 8);
        } else {
                memcpy(req->priv.initiator_port_id,
                       &target->initiator_ext, 8);
                memcpy(req->priv.initiator_port_id + 8,
                       &target->path.sgid.global.interface_id, 8);
                memcpy(req->priv.target_port_id,     &target->id_ext, 8);
                memcpy(req->priv.target_port_id + 8, &target->ioc_guid, 8);
        }

        /*
         * Topspin/Cisco SRP targets will reject our login unless we
         * zero out the first 8 bytes of our initiator port ID and set
         * the second 8 bytes to the local node GUID.
         */
        if (srp_target_is_topspin(target)) {
                shost_printk(KERN_DEBUG, target->scsi_host,
                             PFX "Topspin/Cisco initiator port ID workaround "
                             "activated for target GUID %016llx\n",
                             (unsigned long long) be64_to_cpu(target->ioc_guid));
                memset(req->priv.initiator_port_id, 0, 8);
                memcpy(req->priv.initiator_port_id + 8,
                       &target->srp_host->srp_dev->dev->node_guid, 8);
        }

        status = ib_send_cm_req(target->cm_id, &req->param);

        kfree(req);

        return status;
}

static bool srp_queue_remove_work(struct srp_target_port *target)
{
        bool changed = false;

        spin_lock_irq(&target->lock);
        if (target->state != SRP_TARGET_REMOVED) {
                target->state = SRP_TARGET_REMOVED;
                changed = true;
        }
        spin_unlock_irq(&target->lock);

        if (changed)
                queue_work(system_long_wq, &target->remove_work);

        return changed;
}

static bool srp_change_conn_state(struct srp_target_port *target,
                                  bool connected)
{
        bool changed = false;

        spin_lock_irq(&target->lock);
        if (target->connected != connected) {
                target->connected = connected;
                changed = true;
        }
        spin_unlock_irq(&target->lock);

        return changed;
}

static void srp_disconnect_target(struct srp_target_port *target)
{
        if (srp_change_conn_state(target, false)) {
                /* XXX should send SRP_I_LOGOUT request */

                if (ib_send_cm_dreq(target->cm_id, NULL, 0)) {
                        shost_printk(KERN_DEBUG, target->scsi_host,
                                     PFX "Sending CM DREQ failed\n");
                }
        }
}

static void srp_free_req_data(struct srp_target_port *target)
{
        struct ib_device *ibdev = target->srp_host->srp_dev->dev;
        struct srp_request *req;
        int i;

        for (i = 0, req = target->req_ring; i < SRP_CMD_SQ_SIZE; ++i, ++req) {
                kfree(req->fmr_list);
                kfree(req->map_page);
                if (req->indirect_dma_addr) {
                        ib_dma_unmap_single(ibdev, req->indirect_dma_addr,
                                            target->indirect_size,
                                            DMA_TO_DEVICE);
                }
                kfree(req->indirect_desc);
        }
}

/**
 * srp_del_scsi_host_attr() - Remove attributes defined in the host template.
 * @shost: SCSI host whose attributes to remove from sysfs.
 *
 * Note: Any attributes defined in the host template and that did not exist
 * before invocation of this function will be ignored.
 */
static void srp_del_scsi_host_attr(struct Scsi_Host *shost)
{
        struct device_attribute **attr;

        for (attr = shost->hostt->shost_attrs; attr && *attr; ++attr)
                device_remove_file(&shost->shost_dev, *attr);
}

static void srp_remove_target(struct srp_target_port *target)
{
        WARN_ON_ONCE(target->state != SRP_TARGET_REMOVED);

        srp_del_scsi_host_attr(target->scsi_host);
        srp_remove_host(target->scsi_host);
        scsi_remove_host(target->scsi_host);
        srp_disconnect_target(target);
        ib_destroy_cm_id(target->cm_id);
        srp_free_target_ib(target);
        srp_free_req_data(target);
        scsi_host_put(target->scsi_host);
}

static void srp_remove_work(struct work_struct *work)
{
        struct srp_target_port *target =
                container_of(work, struct srp_target_port, remove_work);

        WARN_ON_ONCE(target->state != SRP_TARGET_REMOVED);

        srp_remove_target(target);

        spin_lock(&target->srp_host->target_lock);
        list_del(&target->list);
        spin_unlock(&target->srp_host->target_lock);
}

static void srp_rport_delete(struct srp_rport *rport)
{
        struct srp_target_port *target = rport->lld_data;

        srp_queue_remove_work(target);
}

static int srp_connect_target(struct srp_target_port *target)
{
        int retries = 3;
        int ret;

        WARN_ON_ONCE(target->connected);

        target->qp_in_error = false;

        ret = srp_lookup_path(target);
        if (ret)
                return ret;

        while (1) {
                init_completion(&target->done);
                ret = srp_send_req(target);
                if (ret)
                        return ret;
                wait_for_completion(&target->done);

                /*
                 * The CM event handling code will set status to
                 * SRP_PORT_REDIRECT if we get a port redirect REJ
                 * back, or SRP_DLID_REDIRECT if we get a lid/qp
                 * redirect REJ back.
                 */
                switch (target->status) {
                case 0:
                        srp_change_conn_state(target, true);
                        return 0;

                case SRP_PORT_REDIRECT:
                        ret = srp_lookup_path(target);
                        if (ret)
                                return ret;
                        break;

                case SRP_DLID_REDIRECT:
                        break;

                case SRP_STALE_CONN:
                        /* Our current CM id was stale, and is now in timewait.
                         * Try to reconnect with a new one.
                         */
                        if (!retries-- || srp_new_cm_id(target)) {
                                shost_printk(KERN_ERR, target->scsi_host, PFX
                                             "giving up on stale connection\n");
                                target->status = -ECONNRESET;
                                return target->status;
                        }

                        shost_printk(KERN_ERR, target->scsi_host, PFX
                                     "retrying stale connection\n");
                        break;

                default:
                        return target->status;
                }
        }
}

static void srp_unmap_data(struct scsi_cmnd *scmnd,
                           struct srp_target_port *target,
                           struct srp_request *req)
{
        struct ib_device *ibdev = target->srp_host->srp_dev->dev;
        struct ib_pool_fmr **pfmr;

        if (!scsi_sglist(scmnd) ||
            (scmnd->sc_data_direction != DMA_TO_DEVICE &&
             scmnd->sc_data_direction != DMA_FROM_DEVICE))
                return;

        pfmr = req->fmr_list;
        while (req->nfmr--)
                ib_fmr_pool_unmap(*pfmr++);

        ib_dma_unmap_sg(ibdev, scsi_sglist(scmnd), scsi_sg_count(scmnd),
                        scmnd->sc_data_direction);
}

/**
 * srp_claim_req - Take ownership of the scmnd associated with a request.
 * @target: SRP target port.
 * @req: SRP request.
 * @scmnd: If NULL, take ownership of @req->scmnd. If not NULL, only take
 *         ownership of @req->scmnd if it equals @scmnd.
 *
 * Return value:
 * Either NULL or a pointer to the SCSI command the caller became owner of.
 */
static struct scsi_cmnd *srp_claim_req(struct srp_target_port *target,
                                       struct srp_request *req,
                                       struct scsi_cmnd *scmnd)
{
        unsigned long flags;

        spin_lock_irqsave(&target->lock, flags);
        if (!scmnd) {
                scmnd = req->scmnd;
                req->scmnd = NULL;
        } else if (req->scmnd == scmnd) {
                req->scmnd = NULL;
        } else {
                scmnd = NULL;
        }
        spin_unlock_irqrestore(&target->lock, flags);

        return scmnd;
}

/**
 * srp_free_req() - Unmap data and add request to the free request list.
 */
static void srp_free_req(struct srp_target_port *target,
                         struct srp_request *req, struct scsi_cmnd *scmnd,
                         s32 req_lim_delta)
{
        unsigned long flags;

        srp_unmap_data(scmnd, target, req);

        spin_lock_irqsave(&target->lock, flags);
        target->req_lim += req_lim_delta;
        list_add_tail(&req->list, &target->free_reqs);
        spin_unlock_irqrestore(&target->lock, flags);
}

static void srp_reset_req(struct srp_target_port *target, struct srp_request *req)
{
        struct scsi_cmnd *scmnd = srp_claim_req(target, req, NULL);

        if (scmnd) {
                srp_free_req(target, req, scmnd, 0);
                scmnd->result = DID_RESET << 16;
                scmnd->scsi_done(scmnd);
        }
}

static int srp_reconnect_target(struct srp_target_port *target)
{
        struct Scsi_Host *shost = target->scsi_host;
        int i, ret;

        scsi_target_block(&shost->shost_gendev);

        srp_disconnect_target(target);
        /*
         * Now get a new local CM ID so that we avoid confusing the target in
         * case things are really fouled up. Doing so also ensures that all CM
         * callbacks will have finished before a new QP is allocated.
         */
        ret = srp_new_cm_id(target);
        /*
         * Whether or not creating a new CM ID succeeded, create a new
         * QP. This guarantees that all completion callback function
         * invocations have finished before request resetting starts.
         */
        if (ret == 0)
                ret = srp_create_target_ib(target);
        else
                srp_create_target_ib(target);

        for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
                struct srp_request *req = &target->req_ring[i];
                if (req->scmnd)
                        srp_reset_req(target, req);
        }

        INIT_LIST_HEAD(&target->free_tx);
        for (i = 0; i < SRP_SQ_SIZE; ++i)
                list_add(&target->tx_ring[i]->list, &target->free_tx);

        if (ret == 0)
                ret = srp_connect_target(target);

        scsi_target_unblock(&shost->shost_gendev, ret == 0 ? SDEV_RUNNING :
                            SDEV_TRANSPORT_OFFLINE);
        target->transport_offline = !!ret;

        if (ret)
                goto err;

        shost_printk(KERN_INFO, target->scsi_host, PFX "reconnect succeeded\n");

        return ret;

err:
        shost_printk(KERN_ERR, target->scsi_host,
                     PFX "reconnect failed (%d), removing target port.\n", ret);

        /*
         * We couldn't reconnect, so kill our target port off.
         * However, we have to defer the real removal because we
         * are in the context of the SCSI error handler now, which
         * will deadlock if we call scsi_remove_host().
         */
        srp_queue_remove_work(target);

        return ret;
}

static void srp_map_desc(struct srp_map_state *state, dma_addr_t dma_addr,
                         unsigned int dma_len, u32 rkey)
{
        struct srp_direct_buf *desc = state->desc;

        desc->va = cpu_to_be64(dma_addr);
        desc->key = cpu_to_be32(rkey);
        desc->len = cpu_to_be32(dma_len);

        state->total_len += dma_len;
        state->desc++;
        state->ndesc++;
}

static int srp_map_finish_fmr(struct srp_map_state *state,
                              struct srp_target_port *target)
{
        struct srp_device *dev = target->srp_host->srp_dev;
        struct ib_pool_fmr *fmr;
        u64 io_addr = 0;

        if (!state->npages)
                return 0;

        if (state->npages == 1) {
                srp_map_desc(state, state->base_dma_addr, state->fmr_len,
                             target->rkey);
                state->npages = state->fmr_len = 0;
                return 0;
        }

        fmr = ib_fmr_pool_map_phys(dev->fmr_pool, state->pages,
                                   state->npages, io_addr);
        if (IS_ERR(fmr))
                return PTR_ERR(fmr);

        *state->next_fmr++ = fmr;
        state->nfmr++;

        srp_map_desc(state, 0, state->fmr_len, fmr->fmr->rkey);
        state->npages = state->fmr_len = 0;
        return 0;
}

static void srp_map_update_start(struct srp_map_state *state,
                                 struct scatterlist *sg, int sg_index,
                                 dma_addr_t dma_addr)
{
        state->unmapped_sg = sg;
        state->unmapped_index = sg_index;
        state->unmapped_addr = dma_addr;
}

static int srp_map_sg_entry(struct srp_map_state *state,
                            struct srp_target_port *target,
                            struct scatterlist *sg, int sg_index,
                            int use_fmr)
{
        struct srp_device *dev = target->srp_host->srp_dev;
        struct ib_device *ibdev = dev->dev;
        dma_addr_t dma_addr = ib_sg_dma_address(ibdev, sg);
        unsigned int dma_len = ib_sg_dma_len(ibdev, sg);
        unsigned int len;
        int ret;

        if (!dma_len)
                return 0;

        if (use_fmr == SRP_MAP_NO_FMR) {
                /* Once we're in direct map mode for a request, we don't
                 * go back to FMR mode, so no need to update anything
                 * other than the descriptor.
                 */
                srp_map_desc(state, dma_addr, dma_len, target->rkey);
                return 0;
        }

        /* If we start at an offset into the FMR page, don't merge into
         * the current FMR. Finish it out, and use the kernel's MR for this
         * sg entry. This is to avoid potential bugs on some SRP targets
         * that were never quite defined, but went away when the initiator
         * avoided using FMR on such page fragments.
         */
        if (dma_addr & ~dev->fmr_page_mask || dma_len > dev->fmr_max_size) {
                ret = srp_map_finish_fmr(state, target);
                if (ret)
                        return ret;

                srp_map_desc(state, dma_addr, dma_len, target->rkey);
                srp_map_update_start(state, NULL, 0, 0);
                return 0;
        }

        /* If this is the first sg to go into the FMR, save our position.
         * We need to know the first unmapped entry, its index, and the
         * first unmapped address within that entry to be able to restart
         * mapping after an error.
         */
        if (!state->unmapped_sg)
                srp_map_update_start(state, sg, sg_index, dma_addr);

        while (dma_len) {
                if (state->npages == SRP_FMR_SIZE) {
                        ret = srp_map_finish_fmr(state, target);
                        if (ret)
                                return ret;

                        srp_map_update_start(state, sg, sg_index, dma_addr);
                }

                len = min_t(unsigned int, dma_len, dev->fmr_page_size);

                if (!state->npages)
                        state->base_dma_addr = dma_addr;
                state->pages[state->npages++] = dma_addr;
                state->fmr_len += len;
                dma_addr += len;
                dma_len -= len;
        }

        /* If the last entry of the FMR wasn't a full page, then we need to
         * close it out and start a new one -- we can only merge at page
         * boundries.
         */
        ret = 0;
        if (len != dev->fmr_page_size) {
                ret = srp_map_finish_fmr(state, target);
                if (!ret)
                        srp_map_update_start(state, NULL, 0, 0);
        }
        return ret;
}

static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
                        struct srp_request *req)
{
        struct scatterlist *scat, *sg;
        struct srp_cmd *cmd = req->cmd->buf;
        int i, len, nents, count, use_fmr;
        struct srp_device *dev;
        struct ib_device *ibdev;
        struct srp_map_state state;
        struct srp_indirect_buf *indirect_hdr;
        u32 table_len;
        u8 fmt;

        if (!scsi_sglist(scmnd) || scmnd->sc_data_direction == DMA_NONE)
                return sizeof (struct srp_cmd);

        if (scmnd->sc_data_direction != DMA_FROM_DEVICE &&
            scmnd->sc_data_direction != DMA_TO_DEVICE) {
                shost_printk(KERN_WARNING, target->scsi_host,
                             PFX "Unhandled data direction %d\n",
                             scmnd->sc_data_direction);
                return -EINVAL;
        }

        nents = scsi_sg_count(scmnd);
        scat  = scsi_sglist(scmnd);

        dev = target->srp_host->srp_dev;
        ibdev = dev->dev;

        count = ib_dma_map_sg(ibdev, scat, nents, scmnd->sc_data_direction);
        if (unlikely(count == 0))
                return -EIO;

        fmt = SRP_DATA_DESC_DIRECT;
        len = sizeof (struct srp_cmd) + sizeof (struct srp_direct_buf);

        if (count == 1) {
                /*
                 * The midlayer only generated a single gather/scatter
                 * entry, or DMA mapping coalesced everything to a
                 * single entry.  So a direct descriptor along with
                 * the DMA MR suffices.
                 */
                struct srp_direct_buf *buf = (void *) cmd->add_data;

                buf->va  = cpu_to_be64(ib_sg_dma_address(ibdev, scat));
                buf->key = cpu_to_be32(target->rkey);
                buf->len = cpu_to_be32(ib_sg_dma_len(ibdev, scat));

                req->nfmr = 0;
                goto map_complete;
        }

        /* We have more than one scatter/gather entry, so build our indirect
         * descriptor table, trying to merge as many entries with FMR as we
         * can.
         */
        indirect_hdr = (void *) cmd->add_data;

        ib_dma_sync_single_for_cpu(ibdev, req->indirect_dma_addr,
                                   target->indirect_size, DMA_TO_DEVICE);

        memset(&state, 0, sizeof(state));
        state.desc      = req->indirect_desc;
        state.pages     = req->map_page;
        state.next_fmr  = req->fmr_list;

        use_fmr = dev->fmr_pool ? SRP_MAP_ALLOW_FMR : SRP_MAP_NO_FMR;

        for_each_sg(scat, sg, count, i) {
                if (srp_map_sg_entry(&state, target, sg, i, use_fmr)) {
                        /* FMR mapping failed, so backtrack to the first
                         * unmapped entry and continue on without using FMR.
                         */
                        dma_addr_t dma_addr;
                        unsigned int dma_len;

backtrack:
                        sg = state.unmapped_sg;
                        i = state.unmapped_index;

                        dma_addr = ib_sg_dma_address(ibdev, sg);
                        dma_len = ib_sg_dma_len(ibdev, sg);
                        dma_len -= (state.unmapped_addr - dma_addr);
                        dma_addr = state.unmapped_addr;
                        use_fmr = SRP_MAP_NO_FMR;
                        srp_map_desc(&state, dma_addr, dma_len, target->rkey);
                }
        }

        if (use_fmr == SRP_MAP_ALLOW_FMR && srp_map_finish_fmr(&state, target))
                goto backtrack;

        /* We've mapped the request, now pull as much of the indirect
         * descriptor table as we can into the command buffer. If this
         * target is not using an external indirect table, we are
         * guaranteed to fit into the command, as the SCSI layer won't
         * give us more S/G entries than we allow.
         */
        req->nfmr = state.nfmr;
        if (state.ndesc == 1) {
                /* FMR mapping was able to collapse this to one entry,
                 * so use a direct descriptor.
                 */

                struct srp_direct_buf *buf = (void *) cmd->add_data;

                *buf = req->indirect_desc[0];
                goto map_complete;
        }

        if (unlikely(target->cmd_sg_cnt < state.ndesc &&
                                                !target->allow_ext_sg)) {
                shost_printk(KERN_ERR, target->scsi_host,
                             "Could not fit S/G list into SRP_CMD\n");
                return -EIO;
        }

        count = min(state.ndesc, target->cmd_sg_cnt);
        table_len = state.ndesc * sizeof (struct srp_direct_buf);

        fmt = SRP_DATA_DESC_INDIRECT;
        len = sizeof(struct srp_cmd) + sizeof (struct srp_indirect_buf);
        len += count * sizeof (struct srp_direct_buf);

        memcpy(indirect_hdr->desc_list, req->indirect_desc,
               count * sizeof (struct srp_direct_buf));

        indirect_hdr->table_desc.va = cpu_to_be64(req->indirect_dma_addr);
        indirect_hdr->table_desc.key = cpu_to_be32(target->rkey);
        indirect_hdr->table_desc.len = cpu_to_be32(table_len);
        indirect_hdr->len = cpu_to_be32(state.total_len);

        if (scmnd->sc_data_direction == DMA_TO_DEVICE)
                cmd->data_out_desc_cnt = count;
        else
                cmd->data_in_desc_cnt = count;

        ib_dma_sync_single_for_device(ibdev, req->indirect_dma_addr, table_len,
                                      DMA_TO_DEVICE);

map_complete:
        if (scmnd->sc_data_direction == DMA_TO_DEVICE)
                cmd->buf_fmt = fmt << 4;
        else
                cmd->buf_fmt = fmt;

        return len;
}

/*
 * Return an IU and possible credit to the free pool
 */
static void srp_put_tx_iu(struct srp_target_port *target, struct srp_iu *iu,
                          enum srp_iu_type iu_type)
{
        unsigned long flags;

        spin_lock_irqsave(&target->lock, flags);
        list_add(&iu->list, &target->free_tx);
        if (iu_type != SRP_IU_RSP)
                ++target->req_lim;
        spin_unlock_irqrestore(&target->lock, flags);
}

/*
 * Must be called with target->lock held to protect req_lim and free_tx.
 * If IU is not sent, it must be returned using srp_put_tx_iu().
 *
 * Note:
 * An upper limit for the number of allocated information units for each
 * request type is:
 * - SRP_IU_CMD: SRP_CMD_SQ_SIZE, since the SCSI mid-layer never queues
 *   more than Scsi_Host.can_queue requests.
 * - SRP_IU_TSK_MGMT: SRP_TSK_MGMT_SQ_SIZE.
 * - SRP_IU_RSP: 1, since a conforming SRP target never sends more than
 *   one unanswered SRP request to an initiator.
 */
static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target,
                                      enum srp_iu_type iu_type)
{
        s32 rsv = (iu_type == SRP_IU_TSK_MGMT) ? 0 : SRP_TSK_MGMT_SQ_SIZE;
        struct srp_iu *iu;

        srp_send_completion(target->send_cq, target);

        if (list_empty(&target->free_tx))
                return NULL;

        /* Initiator responses to target requests do not consume credits */
        if (iu_type != SRP_IU_RSP) {
                if (target->req_lim <= rsv) {
                        ++target->zero_req_lim;
                        return NULL;
                }

                --target->req_lim;
        }

        iu = list_first_entry(&target->free_tx, struct srp_iu, list);
        list_del(&iu->list);
        return iu;
}

static int srp_post_send(struct srp_target_port *target,
                         struct srp_iu *iu, int len)
{
        struct ib_sge list;
        struct ib_send_wr wr, *bad_wr;

        list.addr   = iu->dma;
        list.length = len;
        list.lkey   = target->lkey;

        wr.next       = NULL;
        wr.wr_id      = (uintptr_t) iu;
        wr.sg_list    = &list;
        wr.num_sge    = 1;
        wr.opcode     = IB_WR_SEND;
        wr.send_flags = IB_SEND_SIGNALED;

        return ib_post_send(target->qp, &wr, &bad_wr);
}

static int srp_post_recv(struct srp_target_port *target, struct srp_iu *iu)
{
        struct ib_recv_wr wr, *bad_wr;
        struct ib_sge list;

        list.addr   = iu->dma;
        list.length = iu->size;
        list.lkey   = target->lkey;

        wr.next     = NULL;
        wr.wr_id    = (uintptr_t) iu;
        wr.sg_list  = &list;
        wr.num_sge  = 1;

        return ib_post_recv(target->qp, &wr, &bad_wr);
}

static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
{
        struct srp_request *req;
        struct scsi_cmnd *scmnd;
        unsigned long flags;

        if (unlikely(rsp->tag & SRP_TAG_TSK_MGMT)) {
                spin_lock_irqsave(&target->lock, flags);
                target->req_lim += be32_to_cpu(rsp->req_lim_delta);
                spin_unlock_irqrestore(&target->lock, flags);

                target->tsk_mgmt_status = -1;
                if (be32_to_cpu(rsp->resp_data_len) >= 4)
                        target->tsk_mgmt_status = rsp->data[3];
                complete(&target->tsk_mgmt_done);
        } else {
                req = &target->req_ring[rsp->tag];
                scmnd = srp_claim_req(target, req, NULL);
                if (!scmnd) {
                        shost_printk(KERN_ERR, target->scsi_host,
                                     "Null scmnd for RSP w/tag %016llx\n",
                                     (unsigned long long) rsp->tag);

                        spin_lock_irqsave(&target->lock, flags);
                        target->req_lim += be32_to_cpu(rsp->req_lim_delta);
                        spin_unlock_irqrestore(&target->lock, flags);

                        return;
                }
                scmnd->result = rsp->status;

                if (rsp->flags & SRP_RSP_FLAG_SNSVALID) {
                        memcpy(scmnd->sense_buffer, rsp->data +
                               be32_to_cpu(rsp->resp_data_len),
                               min_t(int, be32_to_cpu(rsp->sense_data_len),
                                     SCSI_SENSE_BUFFERSIZE));
                }

                if (rsp->flags & (SRP_RSP_FLAG_DOOVER | SRP_RSP_FLAG_DOUNDER))
                        scsi_set_resid(scmnd, be32_to_cpu(rsp->data_out_res_cnt));
                else if (rsp->flags & (SRP_RSP_FLAG_DIOVER | SRP_RSP_FLAG_DIUNDER))
                        scsi_set_resid(scmnd, be32_to_cpu(rsp->data_in_res_cnt));

                srp_free_req(target, req, scmnd,
                             be32_to_cpu(rsp->req_lim_delta));

                scmnd->host_scribble = NULL;
                scmnd->scsi_done(scmnd);
        }
}

static int srp_response_common(struct srp_target_port *target, s32 req_delta,
                               void *rsp, int len)
{
        struct ib_device *dev = target->srp_host->srp_dev->dev;
        unsigned long flags;
        struct srp_iu *iu;
        int err;

        spin_lock_irqsave(&target->lock, flags);
        target->req_lim += req_delta;
        iu = __srp_get_tx_iu(target, SRP_IU_RSP);
        spin_unlock_irqrestore(&target->lock, flags);

        if (!iu) {
                shost_printk(KERN_ERR, target->scsi_host, PFX
                             "no IU available to send response\n");
                return 1;
        }

        ib_dma_sync_single_for_cpu(dev, iu->dma, len, DMA_TO_DEVICE);
        memcpy(iu->buf, rsp, len);
        ib_dma_sync_single_for_device(dev, iu->dma, len, DMA_TO_DEVICE);

        err = srp_post_send(target, iu, len);
        if (err) {
                shost_printk(KERN_ERR, target->scsi_host, PFX
                             "unable to post response: %d\n", err);
                srp_put_tx_iu(target, iu, SRP_IU_RSP);
        }

        return err;
}

static void srp_process_cred_req(struct srp_target_port *target,
                                 struct srp_cred_req *req)
{
        struct srp_cred_rsp rsp = {
                .opcode = SRP_CRED_RSP,
                .tag = req->tag,
        };
        s32 delta = be32_to_cpu(req->req_lim_delta);

        if (srp_response_common(target, delta, &rsp, sizeof rsp))
                shost_printk(KERN_ERR, target->scsi_host, PFX
                             "problems processing SRP_CRED_REQ\n");
}

static void srp_process_aer_req(struct srp_target_port *target,
                                struct srp_aer_req *req)
{
        struct srp_aer_rsp rsp = {
                .opcode = SRP_AER_RSP,
                .tag = req->tag,
        };
        s32 delta = be32_to_cpu(req->req_lim_delta);

        shost_printk(KERN_ERR, target->scsi_host, PFX
                     "ignoring AER for LUN %llu\n", be64_to_cpu(req->lun));

        if (srp_response_common(target, delta, &rsp, sizeof rsp))
                shost_printk(KERN_ERR, target->scsi_host, PFX
                             "problems processing SRP_AER_REQ\n");
}

static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
{
        struct ib_device *dev = target->srp_host->srp_dev->dev;
        struct srp_iu *iu = (struct srp_iu *) (uintptr_t) wc->wr_id;
        int res;
        u8 opcode;

        ib_dma_sync_single_for_cpu(dev, iu->dma, target->max_ti_iu_len,
                                   DMA_FROM_DEVICE);

        opcode = *(u8 *) iu->buf;

        if (0) {
                shost_printk(KERN_ERR, target->scsi_host,
                             PFX "recv completion, opcode 0x%02x\n", opcode);
                print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 8, 1,
                               iu->buf, wc->byte_len, true);
        }

        switch (opcode) {
        case SRP_RSP:
                srp_process_rsp(target, iu->buf);
                break;

        case SRP_CRED_REQ:
                srp_process_cred_req(target, iu->buf);
                break;

        case SRP_AER_REQ:
                srp_process_aer_req(target, iu->buf);
                break;

        case SRP_T_LOGOUT:
                /* XXX Handle target logout */
                shost_printk(KERN_WARNING, target->scsi_host,
                             PFX "Got target logout request\n");
                break;

        default:
                shost_printk(KERN_WARNING, target->scsi_host,
                             PFX "Unhandled SRP opcode 0x%02x\n", opcode);
                break;
        }

        ib_dma_sync_single_for_device(dev, iu->dma, target->max_ti_iu_len,
                                      DMA_FROM_DEVICE);

        res = srp_post_recv(target, iu);
        if (res != 0)
                shost_printk(KERN_ERR, target->scsi_host,
                             PFX "Recv failed with error code %d\n", res);
}

static void srp_handle_qp_err(enum ib_wc_status wc_status,
                              enum ib_wc_opcode wc_opcode,
                              struct srp_target_port *target)
{
        if (target->connected && !target->qp_in_error) {
                shost_printk(KERN_ERR, target->scsi_host,
                             PFX "failed %s status %d\n",
                             wc_opcode & IB_WC_RECV ? "receive" : "send",
                             wc_status);
        }
        target->qp_in_error = true;
}

static void srp_recv_completion(struct ib_cq *cq, void *target_ptr)
{
        struct srp_target_port *target = target_ptr;
        struct ib_wc wc;

        ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
        while (ib_poll_cq(cq, 1, &wc) > 0) {
                if (likely(wc.status == IB_WC_SUCCESS)) {
                        srp_handle_recv(target, &wc);
                } else {
                        srp_handle_qp_err(wc.status, wc.opcode, target);
                }
        }
}

static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
{
        struct srp_target_port *target = target_ptr;
        struct ib_wc wc;
        struct srp_iu *iu;

        while (ib_poll_cq(cq, 1, &wc) > 0) {
                if (likely(wc.status == IB_WC_SUCCESS)) {
                        iu = (struct srp_iu *) (uintptr_t) wc.wr_id;
                        list_add(&iu->list, &target->free_tx);
                } else {
                        srp_handle_qp_err(wc.status, wc.opcode, target);
                }
        }
}

static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
{
        struct srp_target_port *target = host_to_target(shost);
        struct srp_request *req;
        struct srp_iu *iu;
        struct srp_cmd *cmd;
        struct ib_device *dev;
        unsigned long flags;
        int len;

        if (unlikely(target->transport_offline)) {
                scmnd->result = DID_NO_CONNECT << 16;
                scmnd->scsi_done(scmnd);
                return 0;
        }

        spin_lock_irqsave(&target->lock, flags);
        iu = __srp_get_tx_iu(target, SRP_IU_CMD);
        if (!iu)
                goto err_unlock;

        req = list_first_entry(&target->free_reqs, struct srp_request, list);
        list_del(&req->list);
        spin_unlock_irqrestore(&target->lock, flags);

        dev = target->srp_host->srp_dev->dev;
        ib_dma_sync_single_for_cpu(dev, iu->dma, target->max_iu_len,
                                   DMA_TO_DEVICE);

        scmnd->result        = 0;
        scmnd->host_scribble = (void *) req;

        cmd = iu->buf;
        memset(cmd, 0, sizeof *cmd);

        cmd->opcode = SRP_CMD;
        cmd->lun    = cpu_to_be64((u64) scmnd->device->lun << 48);
        cmd->tag    = req->index;
        memcpy(cmd->cdb, scmnd->cmnd, scmnd->cmd_len);

        req->scmnd    = scmnd;
        req->cmd      = iu;

        len = srp_map_data(scmnd, target, req);
        if (len < 0) {
                shost_printk(KERN_ERR, target->scsi_host,
                             PFX "Failed to map data\n");
                goto err_iu;
        }

        ib_dma_sync_single_for_device(dev, iu->dma, target->max_iu_len,
                                      DMA_TO_DEVICE);

        if (srp_post_send(target, iu, len)) {
                shost_printk(KERN_ERR, target->scsi_host, PFX "Send failed\n");
                goto err_unmap;
        }

        return 0;

err_unmap:
        srp_unmap_data(scmnd, target, req);

err_iu:
        srp_put_tx_iu(target, iu, SRP_IU_CMD);

        spin_lock_irqsave(&target->lock, flags);
        list_add(&req->list, &target->free_reqs);

err_unlock:
        spin_unlock_irqrestore(&target->lock, flags);

        return SCSI_MLQUEUE_HOST_BUSY;
}

static int srp_alloc_iu_bufs(struct srp_target_port *target)
{
        int i;

        for (i = 0; i < SRP_RQ_SIZE; ++i) {
                target->rx_ring[i] = srp_alloc_iu(target->srp_host,
                                                  target->max_ti_iu_len,
                                                  GFP_KERNEL, DMA_FROM_DEVICE);
                if (!target->rx_ring[i])
                        goto err;
        }

        for (i = 0; i < SRP_SQ_SIZE; ++i) {
                target->tx_ring[i] = srp_alloc_iu(target->srp_host,
                                                  target->max_iu_len,
                                                  GFP_KERNEL, DMA_TO_DEVICE);
                if (!target->tx_ring[i])
                        goto err;

                list_add(&target->tx_ring[i]->list, &target->free_tx);
        }

        return 0;

err:
        for (i = 0; i < SRP_RQ_SIZE; ++i) {
                srp_free_iu(target->srp_host, target->rx_ring[i]);
                target->rx_ring[i] = NULL;
        }

        for (i = 0; i < SRP_SQ_SIZE; ++i) {
                srp_free_iu(target->srp_host, target->tx_ring[i]);
                target->tx_ring[i] = NULL;
        }

        return -ENOMEM;
}

static uint32_t srp_compute_rq_tmo(struct ib_qp_attr *qp_attr, int attr_mask)
{
        uint64_t T_tr_ns, max_compl_time_ms;
        uint32_t rq_tmo_jiffies;

        /*
         * According to section 11.2.4.2 in the IBTA spec (Modify Queue Pair,
         * table 91), both the QP timeout and the retry count have to be set
         * for RC QP's during the RTR to RTS transition.
         */
        WARN_ON_ONCE((attr_mask & (IB_QP_TIMEOUT | IB_QP_RETRY_CNT)) !=
                     (IB_QP_TIMEOUT | IB_QP_RETRY_CNT));

        /*
         * Set target->rq_tmo_jiffies to one second more than the largest time
         * it can take before an error completion is generated. See also
         * C9-140..142 in the IBTA spec for more information about how to
         * convert the QP Local ACK Timeout value to nanoseconds.
         */
        T_tr_ns = 4096 * (1ULL << qp_attr->timeout);
        max_compl_time_ms = qp_attr->retry_cnt * 4 * T_tr_ns;
        do_div(max_compl_time_ms, NSEC_PER_MSEC);
        rq_tmo_jiffies = msecs_to_jiffies(max_compl_time_ms + 1000);

        return rq_tmo_jiffies;
}

static void srp_cm_rep_handler(struct ib_cm_id *cm_id,
                               struct srp_login_rsp *lrsp,
                               struct srp_target_port *target)
{
        struct ib_qp_attr *qp_attr = NULL;
        int attr_mask = 0;
        int ret;
        int i;

        if (lrsp->opcode == SRP_LOGIN_RSP) {
                target->max_ti_iu_len = be32_to_cpu(lrsp->max_ti_iu_len);
                target->req_lim       = be32_to_cpu(lrsp->req_lim_delta);

                /*
                 * Reserve credits for task management so we don't
                 * bounce requests back to the SCSI mid-layer.
                 */
                target->scsi_host->can_queue
                        = min(target->req_lim - SRP_TSK_MGMT_SQ_SIZE,
                              target->scsi_host->can_queue);
        } else {
                shost_printk(KERN_WARNING, target->scsi_host,
                             PFX "Unhandled RSP opcode %#x\n", lrsp->opcode);
                ret = -ECONNRESET;
                goto error;
        }

        if (!target->rx_ring[0]) {
                ret = srp_alloc_iu_bufs(target);
                if (ret)
                        goto error;
        }

        ret = -ENOMEM;
        qp_attr = kmalloc(sizeof *qp_attr, GFP_KERNEL);
        if (!qp_attr)
                goto error;

        qp_attr->qp_state = IB_QPS_RTR;
        ret = ib_cm_init_qp_attr(cm_id, qp_attr, &attr_mask);
        if (ret)
                goto error_free;

        ret = ib_modify_qp(target->qp, qp_attr, attr_mask);
        if (ret)
                goto error_free;

        for (i = 0; i < SRP_RQ_SIZE; i++) {
                struct srp_iu *iu = target->rx_ring[i];
                ret = srp_post_recv(target, iu);
                if (ret)
                        goto error_free;
        }

        qp_attr->qp_state = IB_QPS_RTS;
        ret = ib_cm_init_qp_attr(cm_id, qp_attr, &attr_mask);
        if (ret)
                goto error_free;

        target->rq_tmo_jiffies = srp_compute_rq_tmo(qp_attr, attr_mask);

        ret = ib_modify_qp(target->qp, qp_attr, attr_mask);
        if (ret)
                goto error_free;

        ret = ib_send_cm_rtu(cm_id, NULL, 0);

error_free:
        kfree(qp_attr);

error:
        target->status = ret;
}

static void srp_cm_rej_handler(struct ib_cm_id *cm_id,
                               struct ib_cm_event *event,
                               struct srp_target_port *target)
{
        struct Scsi_Host *shost = target->scsi_host;
        struct ib_class_port_info *cpi;
        int opcode;

        switch (event->param.rej_rcvd.reason) {
        case IB_CM_REJ_PORT_CM_REDIRECT:
                cpi = event->param.rej_rcvd.ari;
                target->path.dlid = cpi->redirect_lid;
                target->path.pkey = cpi->redirect_pkey;
                cm_id->remote_cm_qpn = be32_to_cpu(cpi->redirect_qp) & 0x00ffffff;
                memcpy(target->path.dgid.raw, cpi->redirect_gid, 16);

                target->status = target->path.dlid ?
                        SRP_DLID_REDIRECT : SRP_PORT_REDIRECT;
                break;

        case IB_CM_REJ_PORT_REDIRECT:
                if (srp_target_is_topspin(target)) {
                        /*
                         * Topspin/Cisco SRP gateways incorrectly send
                         * reject reason code 25 when they mean 24
                         * (port redirect).
                         */
                        memcpy(target->path.dgid.raw,
                               event->param.rej_rcvd.ari, 16);

                        shost_printk(KERN_DEBUG, shost,
                                     PFX "Topspin/Cisco redirect to target port GID %016llx%016llx\n",
                                     (unsigned long long) be64_to_cpu(target->path.dgid.global.subnet_prefix),
                                     (unsigned long long) be64_to_cpu(target->path.dgid.global.interface_id));

                        target->status = SRP_PORT_REDIRECT;
                } else {
                        shost_printk(KERN_WARNING, shost,
                                     "  REJ reason: IB_CM_REJ_PORT_REDIRECT\n");
                        target->status = -ECONNRESET;
                }
                break;

        case IB_CM_REJ_DUPLICATE_LOCAL_COMM_ID:
                shost_printk(KERN_WARNING, shost,
                            "  REJ reason: IB_CM_REJ_DUPLICATE_LOCAL_COMM_ID\n");
                target->status = -ECONNRESET;
                break;

        case IB_CM_REJ_CONSUMER_DEFINED:
                opcode = *(u8 *) event->private_data;
                if (opcode == SRP_LOGIN_REJ) {
                        struct srp_login_rej *rej = event->private_data;
                        u32 reason = be32_to_cpu(rej->reason);

                        if (reason == SRP_LOGIN_REJ_REQ_IT_IU_LENGTH_TOO_LARGE)
                                shost_printk(KERN_WARNING, shost,
                                             PFX "SRP_LOGIN_REJ: requested max_it_iu_len too large\n");
                        else
                                shost_printk(KERN_WARNING, shost,
                                            PFX "SRP LOGIN REJECTED, reason 0x%08x\n", reason);
                } else
                        shost_printk(KERN_WARNING, shost,
                                     "  REJ reason: IB_CM_REJ_CONSUMER_DEFINED,"
                                     " opcode 0x%02x\n", opcode);
                target->status = -ECONNRESET;
                break;

        case IB_CM_REJ_STALE_CONN:
                shost_printk(KERN_WARNING, shost, "  REJ reason: stale connection\n");
                target->status = SRP_STALE_CONN;
                break;

        default:
                shost_printk(KERN_WARNING, shost, "  REJ reason 0x%x\n",
                             event->param.rej_rcvd.reason);
                target->status = -ECONNRESET;
        }
}

static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
{
        struct srp_target_port *target = cm_id->context;
        int comp = 0;

        switch (event->event) {
        case IB_CM_REQ_ERROR:
                shost_printk(KERN_DEBUG, target->scsi_host,
                             PFX "Sending CM REQ failed\n");
                comp = 1;
                target->status = -ECONNRESET;
                break;

        case IB_CM_REP_RECEIVED:
                comp = 1;
                srp_cm_rep_handler(cm_id, event->private_data, target);
                break;

        case IB_CM_REJ_RECEIVED:
                shost_printk(KERN_DEBUG, target->scsi_host, PFX "REJ received\n");
                comp = 1;

                srp_cm_rej_handler(cm_id, event, target);
                break;

        case IB_CM_DREQ_RECEIVED:
                shost_printk(KERN_WARNING, target->scsi_host,
                             PFX "DREQ received - connection closed\n");
                srp_change_conn_state(target, false);
                if (ib_send_cm_drep(cm_id, NULL, 0))
                        shost_printk(KERN_ERR, target->scsi_host,
                                     PFX "Sending CM DREP failed\n");
                break;

        case IB_CM_TIMEWAIT_EXIT:
                shost_printk(KERN_ERR, target->scsi_host,
                             PFX "connection closed\n");

                target->status = 0;
                break;

        case IB_CM_MRA_RECEIVED:
        case IB_CM_DREQ_ERROR:
        case IB_CM_DREP_RECEIVED:
                break;

        default:
                shost_printk(KERN_WARNING, target->scsi_host,
                             PFX "Unhandled CM event %d\n", event->event);
                break;
        }

        if (comp)
                complete(&target->done);

        return 0;
}

static int srp_send_tsk_mgmt(struct srp_target_port *target,
                             u64 req_tag, unsigned int lun, u8 func)
{
        struct ib_device *dev = target->srp_host->srp_dev->dev;
        struct srp_iu *iu;
        struct srp_tsk_mgmt *tsk_mgmt;

        if (!target->connected || target->qp_in_error)
                return -1;

        init_completion(&target->tsk_mgmt_done);

        spin_lock_irq(&target->lock);
        iu = __srp_get_tx_iu(target, SRP_IU_TSK_MGMT);
        spin_unlock_irq(&target->lock);

        if (!iu)
                return -1;

        ib_dma_sync_single_for_cpu(dev, iu->dma, sizeof *tsk_mgmt,
                                   DMA_TO_DEVICE);
        tsk_mgmt = iu->buf;
        memset(tsk_mgmt, 0, sizeof *tsk_mgmt);

        tsk_mgmt->opcode        = SRP_TSK_MGMT;
        tsk_mgmt->lun           = cpu_to_be64((u64) lun << 48);
        tsk_mgmt->tag           = req_tag | SRP_TAG_TSK_MGMT;
        tsk_mgmt->tsk_mgmt_func = func;
        tsk_mgmt->task_tag      = req_tag;

        ib_dma_sync_single_for_device(dev, iu->dma, sizeof *tsk_mgmt,
                                      DMA_TO_DEVICE);
        if (srp_post_send(target, iu, sizeof *tsk_mgmt)) {
                srp_put_tx_iu(target, iu, SRP_IU_TSK_MGMT);
                return -1;
        }

        if (!wait_for_completion_timeout(&target->tsk_mgmt_done,
                                         msecs_to_jiffies(SRP_ABORT_TIMEOUT_MS)))
                return -1;

        return 0;
}

static int srp_abort(struct scsi_cmnd *scmnd)
{
        struct srp_target_port *target = host_to_target(scmnd->device->host);
        struct srp_request *req = (struct srp_request *) scmnd->host_scribble;
        int ret;

        shost_printk(KERN_ERR, target->scsi_host, "SRP abort called\n");

        if (!req || !srp_claim_req(target, req, scmnd))
                return FAILED;
        if (srp_send_tsk_mgmt(target, req->index, scmnd->device->lun,
                              SRP_TSK_ABORT_TASK) == 0)
                ret = SUCCESS;
        else if (target->transport_offline)
                ret = FAST_IO_FAIL;
        else
                ret = FAILED;
        srp_free_req(target, req, scmnd, 0);
        scmnd->result = DID_ABORT << 16;
        scmnd->scsi_done(scmnd);

        return ret;
}

static int srp_reset_device(struct scsi_cmnd *scmnd)
{
        struct srp_target_port *target = host_to_target(scmnd->device->host);
        int i;

        shost_printk(KERN_ERR, target->scsi_host, "SRP reset_device called\n");

        if (srp_send_tsk_mgmt(target, SRP_TAG_NO_REQ, scmnd->device->lun,
                              SRP_TSK_LUN_RESET))
                return FAILED;
        if (target->tsk_mgmt_status)
                return FAILED;

        for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
                struct srp_request *req = &target->req_ring[i];
                if (req->scmnd && req->scmnd->device == scmnd->device)
                        srp_reset_req(target, req);
        }

        return SUCCESS;
}

static int srp_reset_host(struct scsi_cmnd *scmnd)
{
        struct srp_target_port *target = host_to_target(scmnd->device->host);
        int ret = FAILED;

        shost_printk(KERN_ERR, target->scsi_host, PFX "SRP reset_host called\n");

        if (!srp_reconnect_target(target))
                ret = SUCCESS;

        return ret;
}

static int srp_slave_configure(struct scsi_device *sdev)
{
        struct Scsi_Host *shost = sdev->host;
        struct srp_target_port *target = host_to_target(shost);
        struct request_queue *q = sdev->request_queue;
        unsigned long timeout;

        if (sdev->type == TYPE_DISK) {
                timeout = max_t(unsigned, 30 * HZ, target->rq_tmo_jiffies);
                blk_queue_rq_timeout(q, timeout);
        }

        return 0;
}

static ssize_t show_id_ext(struct device *dev, struct device_attribute *attr,
                           char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "0x%016llx\n",
                       (unsigned long long) be64_to_cpu(target->id_ext));
}

static ssize_t show_ioc_guid(struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "0x%016llx\n",
                       (unsigned long long) be64_to_cpu(target->ioc_guid));
}

static ssize_t show_service_id(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "0x%016llx\n",
                       (unsigned long long) be64_to_cpu(target->service_id));
}

static ssize_t show_pkey(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "0x%04x\n", be16_to_cpu(target->path.pkey));
}

static ssize_t show_dgid(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%pI6\n", target->path.dgid.raw);
}

static ssize_t show_orig_dgid(struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%pI6\n", target->orig_dgid);
}

static ssize_t show_req_lim(struct device *dev,
                            struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%d\n", target->req_lim);
}

static ssize_t show_zero_req_lim(struct device *dev,
                                 struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%d\n", target->zero_req_lim);
}

static ssize_t show_local_ib_port(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%d\n", target->srp_host->port);
}

static ssize_t show_local_ib_device(struct device *dev,
                                    struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%s\n", target->srp_host->srp_dev->dev->name);
}

static ssize_t show_comp_vector(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%d\n", target->comp_vector);
}

static ssize_t show_cmd_sg_entries(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%u\n", target->cmd_sg_cnt);
}

static ssize_t show_allow_ext_sg(struct device *dev,
                                 struct device_attribute *attr, char *buf)
{
        struct srp_target_port *target = host_to_target(class_to_shost(dev));

        return sprintf(buf, "%s\n", target->allow_ext_sg ? "true" : "false");
}

static DEVICE_ATTR(id_ext,          S_IRUGO, show_id_ext,          NULL);
static DEVICE_ATTR(ioc_guid,        S_IRUGO, show_ioc_guid,        NULL);
static DEVICE_ATTR(service_id,      S_IRUGO, show_service_id,      NULL);
static DEVICE_ATTR(pkey,            S_IRUGO, show_pkey,            NULL);
static DEVICE_ATTR(dgid,            S_IRUGO, show_dgid,            NULL);
static DEVICE_ATTR(orig_dgid,       S_IRUGO, show_orig_dgid,       NULL);
static DEVICE_ATTR(req_lim,         S_IRUGO, show_req_lim,         NULL);
static DEVICE_ATTR(zero_req_lim,    S_IRUGO, show_zero_req_lim,    NULL);
static DEVICE_ATTR(local_ib_port,   S_IRUGO, show_local_ib_port,   NULL);
static DEVICE_ATTR(local_ib_device, S_IRUGO, show_local_ib_device, NULL);
static DEVICE_ATTR(comp_vector,     S_IRUGO, show_comp_vector,     NULL);
static DEVICE_ATTR(cmd_sg_entries,  S_IRUGO, show_cmd_sg_entries,  NULL);
static DEVICE_ATTR(allow_ext_sg,    S_IRUGO, show_allow_ext_sg,    NULL);

static struct device_attribute *srp_host_attrs[] = {
        &dev_attr_id_ext,
        &dev_attr_ioc_guid,
        &dev_attr_service_id,
        &dev_attr_pkey,
        &dev_attr_dgid,
        &dev_attr_orig_dgid,
        &dev_attr_req_lim,
        &dev_attr_zero_req_lim,
        &dev_attr_local_ib_port,
        &dev_attr_local_ib_device,
        &dev_attr_comp_vector,
        &dev_attr_cmd_sg_entries,
        &dev_attr_allow_ext_sg,
        NULL
};

static struct scsi_host_template srp_template = {
        .module                         = THIS_MODULE,
        .name                           = "InfiniBand SRP initiator",
        .proc_name                      = DRV_NAME,
        .slave_configure                = srp_slave_configure,
        .info                           = srp_target_info,
        .queuecommand                   = srp_queuecommand,
        .eh_abort_handler               = srp_abort,
        .eh_device_reset_handler        = srp_reset_device,
        .eh_host_reset_handler          = srp_reset_host,
        .skip_settle_delay              = true,
        .sg_tablesize                   = SRP_DEF_SG_TABLESIZE,
        .can_queue                      = SRP_CMD_SQ_SIZE,
        .this_id                        = -1,
        .cmd_per_lun                    = SRP_CMD_SQ_SIZE,
        .use_clustering                 = ENABLE_CLUSTERING,
        .shost_attrs                    = srp_host_attrs
};

static int srp_add_target(struct srp_host *host, struct srp_target_port *target)
{
        struct srp_rport_identifiers ids;
        struct srp_rport *rport;

        sprintf(target->target_name, "SRP.T10:%016llX",
                 (unsigned long long) be64_to_cpu(target->id_ext));

        if (scsi_add_host(target->scsi_host, host->srp_dev->dev->dma_device))
                return -ENODEV;

        memcpy(ids.port_id, &target->id_ext, 8);
        memcpy(ids.port_id + 8, &target->ioc_guid, 8);
        ids.roles = SRP_RPORT_ROLE_TARGET;
        rport = srp_rport_add(target->scsi_host, &ids);
        if (IS_ERR(rport)) {
                scsi_remove_host(target->scsi_host);
                return PTR_ERR(rport);
        }

        rport->lld_data = target;

        spin_lock(&host->target_lock);
        list_add_tail(&target->list, &host->target_list);
        spin_unlock(&host->target_lock);

        target->state = SRP_TARGET_LIVE;

        scsi_scan_target(&target->scsi_host->shost_gendev,
                         0, target->scsi_id, SCAN_WILD_CARD, 0);

        return 0;
}

static void srp_release_dev(struct device *dev)
{
        struct srp_host *host =
                container_of(dev, struct srp_host, dev);

        complete(&host->released);
}

static struct class srp_class = {
        .name    = "infiniband_srp",
        .dev_release = srp_release_dev
};

/**
 * srp_conn_unique() - check whether the connection to a target is unique
 */
static bool srp_conn_unique(struct srp_host *host,
                            struct srp_target_port *target)
{
        struct srp_target_port *t;
        bool ret = false;

        if (target->state == SRP_TARGET_REMOVED)
                goto out;

        ret = true;

        spin_lock(&host->target_lock);
        list_for_each_entry(t, &host->target_list, list) {
                if (t != target &&
                    target->id_ext == t->id_ext &&
                    target->ioc_guid == t->ioc_guid &&
                    target->initiator_ext == t->initiator_ext) {
                        ret = false;
                        break;
                }
        }
        spin_unlock(&host->target_lock);

out:
        return ret;
}

/*
 * Target ports are added by writing
 *
 *     id_ext=<SRP ID ext>,ioc_guid=<SRP IOC GUID>,dgid=<dest GID>,
 *     pkey=<P_Key>,service_id=<service ID>
 *
 * to the add_target sysfs attribute.
 */
enum {
        SRP_OPT_ERR             = 0,
        SRP_OPT_ID_EXT          = 1 << 0,
        SRP_OPT_IOC_GUID        = 1 << 1,
        SRP_OPT_DGID            = 1 << 2,
        SRP_OPT_PKEY            = 1 << 3,
        SRP_OPT_SERVICE_ID      = 1 << 4,
        SRP_OPT_MAX_SECT        = 1 << 5,
        SRP_OPT_MAX_CMD_PER_LUN = 1 << 6,
        SRP_OPT_IO_CLASS        = 1 << 7,
        SRP_OPT_INITIATOR_EXT   = 1 << 8,
        SRP_OPT_CMD_SG_ENTRIES  = 1 << 9,
        SRP_OPT_ALLOW_EXT_SG    = 1 << 10,
        SRP_OPT_SG_TABLESIZE    = 1 << 11,
        SRP_OPT_COMP_VECTOR     = 1 << 12,
        SRP_OPT_ALL             = (SRP_OPT_ID_EXT       |
                                   SRP_OPT_IOC_GUID     |
                                   SRP_OPT_DGID         |
                                   SRP_OPT_PKEY         |
                                   SRP_OPT_SERVICE_ID),
};

static const match_table_t srp_opt_tokens = {
        { SRP_OPT_ID_EXT,               "id_ext=%s"             },
        { SRP_OPT_IOC_GUID,             "ioc_guid=%s"           },
        { SRP_OPT_DGID,                 "dgid=%s"               },
        { SRP_OPT_PKEY,                 "pkey=%x"               },
        { SRP_OPT_SERVICE_ID,           "service_id=%s"         },
        { SRP_OPT_MAX_SECT,             "max_sect=%d"           },
        { SRP_OPT_MAX_CMD_PER_LUN,      "max_cmd_per_lun=%d"    },
        { SRP_OPT_IO_CLASS,             "io_class=%x"           },
        { SRP_OPT_INITIATOR_EXT,        "initiator_ext=%s"      },
        { SRP_OPT_CMD_SG_ENTRIES,       "cmd_sg_entries=%u"     },
        { SRP_OPT_ALLOW_EXT_SG,         "allow_ext_sg=%u"       },
        { SRP_OPT_SG_TABLESIZE,         "sg_tablesize=%u"       },
        { SRP_OPT_COMP_VECTOR,          "comp_vector=%u"        },
        { SRP_OPT_ERR,                  NULL                    }
};

static int srp_parse_options(const char *buf, struct srp_target_port *target)
{
        char *options, *sep_opt;
        char *p;
        char dgid[3];
        substring_t args[MAX_OPT_ARGS];
        int opt_mask = 0;
        int token;
        int ret = -EINVAL;
        int i;

        options = kstrdup(buf, GFP_KERNEL);
        if (!options)
                return -ENOMEM;

        sep_opt = options;
        while ((p = strsep(&sep_opt, ",")) != NULL) {
                if (!*p)
                        continue;

                token = match_token(p, srp_opt_tokens, args);
                opt_mask |= token;

                switch (token) {
                case SRP_OPT_ID_EXT:
                        p = match_strdup(args);
                        if (!p) {
                                ret = -ENOMEM;
                                goto out;
                        }
                        target->id_ext = cpu_to_be64(simple_strtoull(p, NULL, 16));
                        kfree(p);
                        break;

                case SRP_OPT_IOC_GUID:
                        p = match_strdup(args);
                        if (!p) {
                                ret = -ENOMEM;
                                goto out;
                        }
                        target->ioc_guid = cpu_to_be64(simple_strtoull(p, NULL, 16));
                        kfree(p);
                        break;

                case SRP_OPT_DGID:
                        p = match_strdup(args);
                        if (!p) {
                                ret = -ENOMEM;
                                goto out;
                        }
                        if (strlen(p) != 32) {
                                pr_warn("bad dest GID parameter '%s'\n", p);
                                kfree(p);
                                goto out;
                        }

                        for (i = 0; i < 16; ++i) {
                                strlcpy(dgid, p + i * 2, 3);
                                target->path.dgid.raw[i] = simple_strtoul(dgid, NULL, 16);
                        }
                        kfree(p);
                        memcpy(target->orig_dgid, target->path.dgid.raw, 16);
                        break;

                case SRP_OPT_PKEY:
                        if (match_hex(args, &token)) {
                                pr_warn("bad P_Key parameter '%s'\n", p);
                                goto out;
                        }
                        target->path.pkey = cpu_to_be16(token);
                        break;

                case SRP_OPT_SERVICE_ID:
                        p = match_strdup(args);
                        if (!p) {
                                ret = -ENOMEM;
                                goto out;
                        }
                        target->service_id = cpu_to_be64(simple_strtoull(p, NULL, 16));
                        target->path.service_id = target->service_id;
                        kfree(p);
                        break;

                case SRP_OPT_MAX_SECT:
                        if (match_int(args, &token)) {
                                pr_warn("bad max sect parameter '%s'\n", p);
                                goto out;
                        }
                        target->scsi_host->max_sectors = token;
                        break;

                case SRP_OPT_MAX_CMD_PER_LUN:
                        if (match_int(args, &token)) {
                                pr_warn("bad max cmd_per_lun parameter '%s'\n",
                                        p);
                                goto out;
                        }
                        target->scsi_host->cmd_per_lun = min(token, SRP_CMD_SQ_SIZE);
                        break;

                case SRP_OPT_IO_CLASS:
                        if (match_hex(args, &token)) {
                                pr_warn("bad IO class parameter '%s'\n", p);
                                goto out;
                        }
                        if (token != SRP_REV10_IB_IO_CLASS &&
                            token != SRP_REV16A_IB_IO_CLASS) {
                                pr_warn("unknown IO class parameter value %x specified (use %x or %x).\n",
                                        token, SRP_REV10_IB_IO_CLASS,
                                        SRP_REV16A_IB_IO_CLASS);
                                goto out;
                        }
                        target->io_class = token;
                        break;

                case SRP_OPT_INITIATOR_EXT:
                        p = match_strdup(args);
                        if (!p) {
                                ret = -ENOMEM;
                                goto out;
                        }
                        target->initiator_ext = cpu_to_be64(simple_strtoull(p, NULL, 16));
                        kfree(p);
                        break;

                case SRP_OPT_CMD_SG_ENTRIES:
                        if (match_int(args, &token) || token < 1 || token > 255) {
                                pr_warn("bad max cmd_sg_entries parameter '%s'\n",
                                        p);
                                goto out;
                        }
                        target->cmd_sg_cnt = token;
                        break;

                case SRP_OPT_ALLOW_EXT_SG:
                        if (match_int(args, &token)) {
                                pr_warn("bad allow_ext_sg parameter '%s'\n", p);
                                goto out;
                        }
                        target->allow_ext_sg = !!token;
                        break;

                case SRP_OPT_SG_TABLESIZE:
                        if (match_int(args, &token) || token < 1 ||
                                        token > SCSI_MAX_SG_CHAIN_SEGMENTS) {
                                pr_warn("bad max sg_tablesize parameter '%s'\n",
                                        p);
                                goto out;
                        }
                        target->sg_tablesize = token;
                        break;

                case SRP_OPT_COMP_VECTOR:
                        if (match_int(args, &token) || token < 0) {
                                pr_warn("bad comp_vector parameter '%s'\n", p);
                                goto out;
                        }
                        target->comp_vector = token;
                        break;

                default:
                        pr_warn("unknown parameter or missing value '%s' in target creation request\n",
                                p);
                        goto out;
                }
        }

        if ((opt_mask & SRP_OPT_ALL) == SRP_OPT_ALL)
                ret = 0;
        else
                for (i = 0; i < ARRAY_SIZE(srp_opt_tokens); ++i)
                        if ((srp_opt_tokens[i].token & SRP_OPT_ALL) &&
                            !(srp_opt_tokens[i].token & opt_mask))
                                pr_warn("target creation request is missing parameter '%s'\n",
                                        srp_opt_tokens[i].pattern);

out:
        kfree(options);
        return ret;
}

static ssize_t srp_create_target(struct device *dev,
                                 struct device_attribute *attr,
                                 const char *buf, size_t count)
{
        struct srp_host *host =
                container_of(dev, struct srp_host, dev);
        struct Scsi_Host *target_host;
        struct srp_target_port *target;
        struct ib_device *ibdev = host->srp_dev->dev;
        dma_addr_t dma_addr;
        int i, ret;

        target_host = scsi_host_alloc(&srp_template,
                                      sizeof (struct srp_target_port));
        if (!target_host)
                return -ENOMEM;

        target_host->transportt  = ib_srp_transport_template;
        target_host->max_channel = 0;
        target_host->max_id      = 1;
        target_host->max_lun     = SRP_MAX_LUN;
        target_host->max_cmd_len = sizeof ((struct srp_cmd *) (void *) 0L)->cdb;

        target = host_to_target(target_host);

        target->io_class        = SRP_REV16A_IB_IO_CLASS;
        target->scsi_host       = target_host;
        target->srp_host        = host;
        target->lkey            = host->srp_dev->mr->lkey;
        target->rkey            = host->srp_dev->mr->rkey;
        target->cmd_sg_cnt      = cmd_sg_entries;
        target->sg_tablesize    = indirect_sg_entries ? : cmd_sg_entries;
        target->allow_ext_sg    = allow_ext_sg;

        ret = srp_parse_options(buf, target);
        if (ret)
                goto err;

        if (!srp_conn_unique(target->srp_host, target)) {
                shost_printk(KERN_INFO, target->scsi_host,
                             PFX "Already connected to target port with id_ext=%016llx;ioc_guid=%016llx;initiator_ext=%016llx\n",
                             be64_to_cpu(target->id_ext),
                             be64_to_cpu(target->ioc_guid),
                             be64_to_cpu(target->initiator_ext));
                ret = -EEXIST;
                goto err;
        }

        if (!host->srp_dev->fmr_pool && !target->allow_ext_sg &&
                                target->cmd_sg_cnt < target->sg_tablesize) {
                pr_warn("No FMR pool and no external indirect descriptors, limiting sg_tablesize to cmd_sg_cnt\n");
                target->sg_tablesize = target->cmd_sg_cnt;
        }

        target_host->sg_tablesize = target->sg_tablesize;
        target->indirect_size = target->sg_tablesize *
                                sizeof (struct srp_direct_buf);
        target->max_iu_len = sizeof (struct srp_cmd) +
                             sizeof (struct srp_indirect_buf) +
                             target->cmd_sg_cnt * sizeof (struct srp_direct_buf);

        INIT_WORK(&target->remove_work, srp_remove_work);
        spin_lock_init(&target->lock);
        INIT_LIST_HEAD(&target->free_tx);
        INIT_LIST_HEAD(&target->free_reqs);
        for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
                struct srp_request *req = &target->req_ring[i];

                req->fmr_list = kmalloc(target->cmd_sg_cnt * sizeof (void *),
                                        GFP_KERNEL);
                req->map_page = kmalloc(SRP_FMR_SIZE * sizeof (void *),
                                        GFP_KERNEL);
                req->indirect_desc = kmalloc(target->indirect_size, GFP_KERNEL);
                if (!req->fmr_list || !req->map_page || !req->indirect_desc)
                        goto err_free_mem;

                dma_addr = ib_dma_map_single(ibdev, req->indirect_desc,
                                             target->indirect_size,
                                             DMA_TO_DEVICE);
                if (ib_dma_mapping_error(ibdev, dma_addr))
                        goto err_free_mem;

                req->indirect_dma_addr = dma_addr;
                req->index = i;
                list_add_tail(&req->list, &target->free_reqs);
        }

        ib_query_gid(ibdev, host->port, 0, &target->path.sgid);

        shost_printk(KERN_DEBUG, target->scsi_host, PFX
                     "new target: id_ext %016llx ioc_guid %016llx pkey %04x "
                     "service_id %016llx dgid %pI6\n",
               (unsigned long long) be64_to_cpu(target->id_ext),
               (unsigned long long) be64_to_cpu(target->ioc_guid),
               be16_to_cpu(target->path.pkey),
               (unsigned long long) be64_to_cpu(target->service_id),
               target->path.dgid.raw);

        ret = srp_create_target_ib(target);
        if (ret)
                goto err_free_mem;

        ret = srp_new_cm_id(target);
        if (ret)
                goto err_free_ib;

        ret = srp_connect_target(target);
        if (ret) {
                shost_printk(KERN_ERR, target->scsi_host,
                             PFX "Connection failed\n");
                goto err_cm_id;
        }

        ret = srp_add_target(host, target);
        if (ret)
                goto err_disconnect;

        return count;

err_disconnect:
        srp_disconnect_target(target);

err_cm_id:
        ib_destroy_cm_id(target->cm_id);

err_free_ib:
        srp_free_target_ib(target);

err_free_mem:
        srp_free_req_data(target);

err:
        scsi_host_put(target_host);

        return ret;
}

static DEVICE_ATTR(add_target, S_IWUSR, NULL, srp_create_target);

static ssize_t show_ibdev(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        struct srp_host *host = container_of(dev, struct srp_host, dev);

        return sprintf(buf, "%s\n", host->srp_dev->dev->name);
}

static DEVICE_ATTR(ibdev, S_IRUGO, show_ibdev, NULL);

static ssize_t show_port(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct srp_host *host = container_of(dev, struct srp_host, dev);

        return sprintf(buf, "%d\n", host->port);
}

static DEVICE_ATTR(port, S_IRUGO, show_port, NULL);

static struct srp_host *srp_add_port(struct srp_device *device, u8 port)
{
        struct srp_host *host;

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

        INIT_LIST_HEAD(&host->target_list);
        spin_lock_init(&host->target_lock);
        init_completion(&host->released);
        host->srp_dev = device;
        host->port = port;

        host->dev.class = &srp_class;
        host->dev.parent = device->dev->dma_device;
        dev_set_name(&host->dev, "srp-%s-%d", device->dev->name, port);

        if (device_register(&host->dev))
                goto free_host;
        if (device_create_file(&host->dev, &dev_attr_add_target))
                goto err_class;
        if (device_create_file(&host->dev, &dev_attr_ibdev))
                goto err_class;
        if (device_create_file(&host->dev, &dev_attr_port))
                goto err_class;

        return host;

err_class:
        device_unregister(&host->dev);

free_host:
        kfree(host);

        return NULL;
}

static void srp_add_one(struct ib_device *device)
{
        struct srp_device *srp_dev;
        struct ib_device_attr *dev_attr;
        struct ib_fmr_pool_param fmr_param;
        struct srp_host *host;
        int max_pages_per_fmr, fmr_page_shift, s, e, p;

        dev_attr = kmalloc(sizeof *dev_attr, GFP_KERNEL);
        if (!dev_attr)
                return;

        if (ib_query_device(device, dev_attr)) {
                pr_warn("Query device failed for %s\n", device->name);
                goto free_attr;
        }

        srp_dev = kmalloc(sizeof *srp_dev, GFP_KERNEL);
        if (!srp_dev)
                goto free_attr;

        /*
         * Use the smallest page size supported by the HCA, down to a
         * minimum of 4096 bytes. We're unlikely to build large sglists
         * out of smaller entries.
         */
        fmr_page_shift          = max(12, ffs(dev_attr->page_size_cap) - 1);
        srp_dev->fmr_page_size  = 1 << fmr_page_shift;
        srp_dev->fmr_page_mask  = ~((u64) srp_dev->fmr_page_size - 1);
        srp_dev->fmr_max_size   = srp_dev->fmr_page_size * SRP_FMR_SIZE;

        INIT_LIST_HEAD(&srp_dev->dev_list);

        srp_dev->dev = device;
        srp_dev->pd  = ib_alloc_pd(device);
        if (IS_ERR(srp_dev->pd))
                goto free_dev;

        srp_dev->mr = ib_get_dma_mr(srp_dev->pd,
                                    IB_ACCESS_LOCAL_WRITE |
                                    IB_ACCESS_REMOTE_READ |
                                    IB_ACCESS_REMOTE_WRITE);
        if (IS_ERR(srp_dev->mr))
                goto err_pd;

        for (max_pages_per_fmr = SRP_FMR_SIZE;
                        max_pages_per_fmr >= SRP_FMR_MIN_SIZE;
                        max_pages_per_fmr /= 2, srp_dev->fmr_max_size /= 2) {
                memset(&fmr_param, 0, sizeof fmr_param);
                fmr_param.pool_size         = SRP_FMR_POOL_SIZE;
                fmr_param.dirty_watermark   = SRP_FMR_DIRTY_SIZE;
                fmr_param.cache             = 1;
                fmr_param.max_pages_per_fmr = max_pages_per_fmr;
                fmr_param.page_shift        = fmr_page_shift;
                fmr_param.access            = (IB_ACCESS_LOCAL_WRITE |
                                               IB_ACCESS_REMOTE_WRITE |
                                               IB_ACCESS_REMOTE_READ);

                srp_dev->fmr_pool = ib_create_fmr_pool(srp_dev->pd, &fmr_param);
                if (!IS_ERR(srp_dev->fmr_pool))
                        break;
        }

        if (IS_ERR(srp_dev->fmr_pool))
                srp_dev->fmr_pool = NULL;

        if (device->node_type == RDMA_NODE_IB_SWITCH) {
                s = 0;
                e = 0;
        } else {
                s = 1;
                e = device->phys_port_cnt;
        }

        for (p = s; p <= e; ++p) {
                host = srp_add_port(srp_dev, p);
                if (host)
                        list_add_tail(&host->list, &srp_dev->dev_list);
        }

        ib_set_client_data(device, &srp_client, srp_dev);

        goto free_attr;

err_pd:
        ib_dealloc_pd(srp_dev->pd);

free_dev:
        kfree(srp_dev);

free_attr:
        kfree(dev_attr);
}

static void srp_remove_one(struct ib_device *device)
{
        struct srp_device *srp_dev;
        struct srp_host *host, *tmp_host;
        struct srp_target_port *target;

        srp_dev = ib_get_client_data(device, &srp_client);
        if (!srp_dev)
                return;

        list_for_each_entry_safe(host, tmp_host, &srp_dev->dev_list, list) {
                device_unregister(&host->dev);
                /*
                 * Wait for the sysfs entry to go away, so that no new
                 * target ports can be created.
                 */
                wait_for_completion(&host->released);

                /*
                 * Remove all target ports.
                 */
                spin_lock(&host->target_lock);
                list_for_each_entry(target, &host->target_list, list)
                        srp_queue_remove_work(target);
                spin_unlock(&host->target_lock);

                /*
                 * Wait for target port removal tasks.
                 */
                flush_workqueue(system_long_wq);

                kfree(host);
        }

        if (srp_dev->fmr_pool)
                ib_destroy_fmr_pool(srp_dev->fmr_pool);
        ib_dereg_mr(srp_dev->mr);
        ib_dealloc_pd(srp_dev->pd);

        kfree(srp_dev);
}

static struct srp_function_template ib_srp_transport_functions = {
        .rport_delete            = srp_rport_delete,
};

static int __init srp_init_module(void)
{
        int ret;

        BUILD_BUG_ON(FIELD_SIZEOF(struct ib_wc, wr_id) < sizeof(void *));

        if (srp_sg_tablesize) {
                pr_warn("srp_sg_tablesize is deprecated, please use cmd_sg_entries\n");
                if (!cmd_sg_entries)
                        cmd_sg_entries = srp_sg_tablesize;
        }

        if (!cmd_sg_entries)
                cmd_sg_entries = SRP_DEF_SG_TABLESIZE;

        if (cmd_sg_entries > 255) {
                pr_warn("Clamping cmd_sg_entries to 255\n");
                cmd_sg_entries = 255;
        }

        if (!indirect_sg_entries)
                indirect_sg_entries = cmd_sg_entries;
        else if (indirect_sg_entries < cmd_sg_entries) {
                pr_warn("Bumping up indirect_sg_entries to match cmd_sg_entries (%u)\n",
                        cmd_sg_entries);
                indirect_sg_entries = cmd_sg_entries;
        }

        ib_srp_transport_template =
                srp_attach_transport(&ib_srp_transport_functions);
        if (!ib_srp_transport_template)
                return -ENOMEM;

        ret = class_register(&srp_class);
        if (ret) {
                pr_err("couldn't register class infiniband_srp\n");
                srp_release_transport(ib_srp_transport_template);
                return ret;
        }

        ib_sa_register_client(&srp_sa_client);

        ret = ib_register_client(&srp_client);
        if (ret) {
                pr_err("couldn't register IB client\n");
                srp_release_transport(ib_srp_transport_template);
                ib_sa_unregister_client(&srp_sa_client);
                class_unregister(&srp_class);
                return ret;
        }

        return 0;
}

static void __exit srp_cleanup_module(void)
{
        ib_unregister_client(&srp_client);
        ib_sa_unregister_client(&srp_sa_client);
        class_unregister(&srp_class);
        srp_release_transport(ib_srp_transport_template);
}

module_init(srp_init_module);
module_exit(srp_cleanup_module);