ib_srp.c

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/*
 * 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 "0.2"
#define DRV_RELDATE "November 1, 2005"

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;
    int ret;

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

    target->recv_cq = ib_create_cq(target->srp_host->srp_dev->dev,
                       srp_recv_completion, NULL, target, SRP_RQ_SIZE, 0);
    if (IS_ERR(target->recv_cq)) {
        ret = PTR_ERR(target->recv_cq);
        goto err;
    }

    target->send_cq = ib_create_cq(target->srp_host->srp_dev->dev,
                       srp_send_completion, NULL, target, SRP_SQ_SIZE, 0);
    if (IS_ERR(target->send_cq)) {
        ret = PTR_ERR(target->send_cq);
        goto err_recv_cq;
    }

    ib_req_notify_cq(target->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             = target->send_cq;
    init_attr->recv_cq             = target->recv_cq;

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

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

    kfree(init_attr);
    return 0;

err_qp:
    ib_destroy_qp(target->qp);

err_send_cq:
    ib_destroy_cq(target->send_cq);

err_recv_cq:
    ib_destroy_cq(target->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);

    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 void srp_disconnect_target(struct srp_target_port *target)
{
    /* XXX should send SRP_I_LOGOUT request */

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

static bool srp_change_state(struct srp_target_port *target,
                enum srp_target_state old,
                enum srp_target_state new)
{
    bool changed = false;

    spin_lock_irq(&target->lock);
    if (target->state == old) {
        target->state = new;
        changed = true;
    }
    spin_unlock_irq(&target->lock);
    return changed;
}

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);
    }
}

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_work(struct work_struct *work)
{
    struct srp_target_port *target =
        container_of(work, struct srp_target_port, work);

    if (!srp_change_state(target, SRP_TARGET_DEAD, SRP_TARGET_REMOVED))
        return;

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

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

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

    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:
            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);
}

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;
}

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 ib_qp_attr qp_attr;
    struct ib_wc wc;
    int i, ret;

    if (!srp_change_state(target, SRP_TARGET_LIVE, SRP_TARGET_CONNECTING))
        return -EAGAIN;

    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.
     */
    ret = srp_new_cm_id(target);
    if (ret)
        goto err;

    qp_attr.qp_state = IB_QPS_RESET;
    ret = ib_modify_qp(target->qp, &qp_attr, IB_QP_STATE);
    if (ret)
        goto err;

    ret = srp_init_qp(target, target->qp);
    if (ret)
        goto err;

    while (ib_poll_cq(target->recv_cq, 1, &wc) > 0)
        ; /* nothing */
    while (ib_poll_cq(target->send_cq, 1, &wc) > 0)
        ; /* nothing */

    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);

    target->qp_in_error = 0;
    ret = srp_connect_target(target);
    if (ret)
        goto err;

    if (!srp_change_state(target, SRP_TARGET_CONNECTING, SRP_TARGET_LIVE))
        ret = -EAGAIN;

    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().
     *
     * Schedule our work inside the lock to avoid a race with
     * the flush_scheduled_work() in srp_remove_one().
     */
    spin_lock_irq(&target->lock);
    if (target->state == SRP_TARGET_CONNECTING) {
        target->state = SRP_TARGET_DEAD;
        INIT_WORK(&target->work, srp_remove_work);
        queue_work(ib_wq, &target->work);
    }
    spin_unlock_irq(&target->lock);

    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_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 (wc.status) {
            shost_printk(KERN_ERR, target->scsi_host,
                     PFX "failed receive status %d\n",
                     wc.status);
            target->qp_in_error = 1;
            break;
        }

        srp_handle_recv(target, &wc);
    }
}

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 (wc.status) {
            shost_printk(KERN_ERR, target->scsi_host,
                     PFX "failed send status %d\n",
                     wc.status);
            target->qp_in_error = 1;
            break;
        }

        iu = (struct srp_iu *) (uintptr_t) wc.wr_id;
        list_add(&iu->list, &target->free_tx);
    }
}

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 (target->state == SRP_TARGET_CONNECTING)
        goto err;

    if (target->state == SRP_TARGET_DEAD ||
        target->state == SRP_TARGET_REMOVED) {
        scmnd->result = DID_BAD_TARGET << 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);

err:
    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 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;

    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");
        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");

        comp = 1;
        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->state == SRP_TARGET_DEAD ||
        target->state == SRP_TARGET_REMOVED)
        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;

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

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

    return SUCCESS;
}

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 (target->qp_in_error)
        return FAILED;
    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 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_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(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_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,
    .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,
    .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);
    }

    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
};

/*
 * 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_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_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;

        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 (!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);

    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;

    target->qp_in_error = 0;
    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;
    LIST_HEAD(target_list);
    struct srp_target_port *target, *tmp_target;

    srp_dev = ib_get_client_data(device, &srp_client);

    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);

        /*
         * Mark all target ports as removed, so we stop queueing
         * commands and don't try to reconnect.
         */
        spin_lock(&host->target_lock);
        list_for_each_entry(target, &host->target_list, list) {
            spin_lock_irq(&target->lock);
            target->state = SRP_TARGET_REMOVED;
            spin_unlock_irq(&target->lock);
        }
        spin_unlock(&host->target_lock);

        /*
         * Wait for any reconnection tasks that may have
         * started before we marked our target ports as
         * removed, and any target port removal tasks.
         */
        flush_workqueue(ib_wq);

        list_for_each_entry_safe(target, tmp_target,
                     &host->target_list, list) {
            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);
        }

        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 = {
};

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);