/*
 * Copyright (c) 2006 - 2009 Mellanox Technology Inc.  All rights reserved.
 * Copyright (C) 2008 - 2011 Bart Van Assche <bvanassche@acm.org>.
 *
 * 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.
 *
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/ctype.h>
#include <linux/kthread.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/atomic.h>
#include <scsi/scsi_proto.h>
#include <scsi/scsi_tcq.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include "ib_srpt.h"

/* Name of this kernel module. */
#define DRV_NAME                "ib_srpt"
#define DRV_VERSION             "2.0.0"
#define DRV_RELDATE             "2011-02-14"

#define SRPT_ID_STRING  "Linux SRP target"

#undef pr_fmt
#define pr_fmt(fmt) DRV_NAME " " fmt

MODULE_AUTHOR("Vu Pham and Bart Van Assche");
MODULE_DESCRIPTION("InfiniBand SCSI RDMA Protocol target "
                   "v" DRV_VERSION " (" DRV_RELDATE ")");
MODULE_LICENSE("Dual BSD/GPL");

/*
 * Global Variables
 */

static u64 srpt_service_guid;
static DEFINE_SPINLOCK(srpt_dev_lock);  /* Protects srpt_dev_list. */
static LIST_HEAD(srpt_dev_list);        /* List of srpt_device structures. */

static unsigned srp_max_req_size = DEFAULT_MAX_REQ_SIZE;
module_param(srp_max_req_size, int, 0444);
MODULE_PARM_DESC(srp_max_req_size,
                 "Maximum size of SRP request messages in bytes.");

static int srpt_srq_size = DEFAULT_SRPT_SRQ_SIZE;
module_param(srpt_srq_size, int, 0444);
MODULE_PARM_DESC(srpt_srq_size,
                 "Shared receive queue (SRQ) size.");

static int srpt_get_u64_x(char *buffer, struct kernel_param *kp)
{
        return sprintf(buffer, "0x%016llx", *(u64 *)kp->arg);
}
module_param_call(srpt_service_guid, NULL, srpt_get_u64_x, &srpt_service_guid,
                  0444);
MODULE_PARM_DESC(srpt_service_guid,
                 "Using this value for ioc_guid, id_ext, and cm_listen_id"
                 " instead of using the node_guid of the first HCA.");

static struct ib_client srpt_client;
static void srpt_release_cmd(struct se_cmd *se_cmd);
static void srpt_free_ch(struct kref *kref);
static int srpt_queue_status(struct se_cmd *cmd);
static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc);
static void srpt_send_done(struct ib_cq *cq, struct ib_wc *wc);
static void srpt_process_wait_list(struct srpt_rdma_ch *ch);

/*
 * The only allowed channel state changes are those that change the channel
 * state into a state with a higher numerical value. Hence the new > prev test.
 */
static bool srpt_set_ch_state(struct srpt_rdma_ch *ch, enum rdma_ch_state new)
{
        unsigned long flags;
        enum rdma_ch_state prev;
        bool changed = false;

        spin_lock_irqsave(&ch->spinlock, flags);
        prev = ch->state;
        if (new > prev) {
                ch->state = new;
                changed = true;
        }
        spin_unlock_irqrestore(&ch->spinlock, flags);

        return changed;
}

/**
 * srpt_event_handler() - Asynchronous IB event callback function.
 *
 * Callback function called by the InfiniBand core when an asynchronous IB
 * event occurs. This callback may occur in interrupt context. See also
 * section 11.5.2, Set Asynchronous Event Handler in the InfiniBand
 * Architecture Specification.
 */
static void srpt_event_handler(struct ib_event_handler *handler,
                               struct ib_event *event)
{
        struct srpt_device *sdev;
        struct srpt_port *sport;

        sdev = ib_get_client_data(event->device, &srpt_client);
        if (!sdev || sdev->device != event->device)
                return;

        pr_debug("ASYNC event= %d on device= %s\n", event->event,
                 sdev->device->name);

        switch (event->event) {
        case IB_EVENT_PORT_ERR:
                if (event->element.port_num <= sdev->device->phys_port_cnt) {
                        sport = &sdev->port[event->element.port_num - 1];
                        sport->lid = 0;
                        sport->sm_lid = 0;
                }
                break;
        case IB_EVENT_PORT_ACTIVE:
        case IB_EVENT_LID_CHANGE:
        case IB_EVENT_PKEY_CHANGE:
        case IB_EVENT_SM_CHANGE:
        case IB_EVENT_CLIENT_REREGISTER:
        case IB_EVENT_GID_CHANGE:
                /* Refresh port data asynchronously. */
                if (event->element.port_num <= sdev->device->phys_port_cnt) {
                        sport = &sdev->port[event->element.port_num - 1];
                        if (!sport->lid && !sport->sm_lid)
                                schedule_work(&sport->work);
                }
                break;
        default:
                pr_err("received unrecognized IB event %d\n",
                       event->event);
                break;
        }
}

/**
 * srpt_srq_event() - SRQ event callback function.
 */
static void srpt_srq_event(struct ib_event *event, void *ctx)
{
        pr_info("SRQ event %d\n", event->event);
}

static const char *get_ch_state_name(enum rdma_ch_state s)
{
        switch (s) {
        case CH_CONNECTING:
                return "connecting";
        case CH_LIVE:
                return "live";
        case CH_DISCONNECTING:
                return "disconnecting";
        case CH_DRAINING:
                return "draining";
        case CH_DISCONNECTED:
                return "disconnected";
        }
        return "???";
}

/**
 * srpt_qp_event() - QP event callback function.
 */
static void srpt_qp_event(struct ib_event *event, struct srpt_rdma_ch *ch)
{
        pr_debug("QP event %d on cm_id=%p sess_name=%s state=%d\n",
                 event->event, ch->cm_id, ch->sess_name, ch->state);

        switch (event->event) {
        case IB_EVENT_COMM_EST:
                ib_cm_notify(ch->cm_id, event->event);
                break;
        case IB_EVENT_QP_LAST_WQE_REACHED:
                pr_debug("%s-%d, state %s: received Last WQE event.\n",
                         ch->sess_name, ch->qp->qp_num,
                         get_ch_state_name(ch->state));
                break;
        default:
                pr_err("received unrecognized IB QP event %d\n", event->event);
                break;
        }
}

/**
 * srpt_set_ioc() - Helper function for initializing an IOUnitInfo structure.
 *
 * @slot: one-based slot number.
 * @value: four-bit value.
 *
 * Copies the lowest four bits of value in element slot of the array of four
 * bit elements called c_list (controller list). The index slot is one-based.
 */
static void srpt_set_ioc(u8 *c_list, u32 slot, u8 value)
{
        u16 id;
        u8 tmp;

        id = (slot - 1) / 2;
        if (slot & 0x1) {
                tmp = c_list[id] & 0xf;
                c_list[id] = (value << 4) | tmp;
        } else {
                tmp = c_list[id] & 0xf0;
                c_list[id] = (value & 0xf) | tmp;
        }
}

/**
 * srpt_get_class_port_info() - Copy ClassPortInfo to a management datagram.
 *
 * See also section 16.3.3.1 ClassPortInfo in the InfiniBand Architecture
 * Specification.
 */
static void srpt_get_class_port_info(struct ib_dm_mad *mad)
{
        struct ib_class_port_info *cif;

        cif = (struct ib_class_port_info *)mad->data;
        memset(cif, 0, sizeof(*cif));
        cif->base_version = 1;
        cif->class_version = 1;

        ib_set_cpi_resp_time(cif, 20);
        mad->mad_hdr.status = 0;
}

/**
 * srpt_get_iou() - Write IOUnitInfo to a management datagram.
 *
 * See also section 16.3.3.3 IOUnitInfo in the InfiniBand Architecture
 * Specification. See also section B.7, table B.6 in the SRP r16a document.
 */
static void srpt_get_iou(struct ib_dm_mad *mad)
{
        struct ib_dm_iou_info *ioui;
        u8 slot;
        int i;

        ioui = (struct ib_dm_iou_info *)mad->data;
        ioui->change_id = cpu_to_be16(1);
        ioui->max_controllers = 16;

        /* set present for slot 1 and empty for the rest */
        srpt_set_ioc(ioui->controller_list, 1, 1);
        for (i = 1, slot = 2; i < 16; i++, slot++)
                srpt_set_ioc(ioui->controller_list, slot, 0);

        mad->mad_hdr.status = 0;
}

/**
 * srpt_get_ioc() - Write IOControllerprofile to a management datagram.
 *
 * See also section 16.3.3.4 IOControllerProfile in the InfiniBand
 * Architecture Specification. See also section B.7, table B.7 in the SRP
 * r16a document.
 */
static void srpt_get_ioc(struct srpt_port *sport, u32 slot,
                         struct ib_dm_mad *mad)
{
        struct srpt_device *sdev = sport->sdev;
        struct ib_dm_ioc_profile *iocp;

        iocp = (struct ib_dm_ioc_profile *)mad->data;

        if (!slot || slot > 16) {
                mad->mad_hdr.status
                        = cpu_to_be16(DM_MAD_STATUS_INVALID_FIELD);
                return;
        }

        if (slot > 2) {
                mad->mad_hdr.status
                        = cpu_to_be16(DM_MAD_STATUS_NO_IOC);
                return;
        }

        memset(iocp, 0, sizeof(*iocp));
        strcpy(iocp->id_string, SRPT_ID_STRING);
        iocp->guid = cpu_to_be64(srpt_service_guid);
        iocp->vendor_id = cpu_to_be32(sdev->device->attrs.vendor_id);
        iocp->device_id = cpu_to_be32(sdev->device->attrs.vendor_part_id);
        iocp->device_version = cpu_to_be16(sdev->device->attrs.hw_ver);
        iocp->subsys_vendor_id = cpu_to_be32(sdev->device->attrs.vendor_id);
        iocp->subsys_device_id = 0x0;
        iocp->io_class = cpu_to_be16(SRP_REV16A_IB_IO_CLASS);
        iocp->io_subclass = cpu_to_be16(SRP_IO_SUBCLASS);
        iocp->protocol = cpu_to_be16(SRP_PROTOCOL);
        iocp->protocol_version = cpu_to_be16(SRP_PROTOCOL_VERSION);
        iocp->send_queue_depth = cpu_to_be16(sdev->srq_size);
        iocp->rdma_read_depth = 4;
        iocp->send_size = cpu_to_be32(srp_max_req_size);
        iocp->rdma_size = cpu_to_be32(min(sport->port_attrib.srp_max_rdma_size,
                                          1U << 24));
        iocp->num_svc_entries = 1;
        iocp->op_cap_mask = SRP_SEND_TO_IOC | SRP_SEND_FROM_IOC |
                SRP_RDMA_READ_FROM_IOC | SRP_RDMA_WRITE_FROM_IOC;

        mad->mad_hdr.status = 0;
}

/**
 * srpt_get_svc_entries() - Write ServiceEntries to a management datagram.
 *
 * See also section 16.3.3.5 ServiceEntries in the InfiniBand Architecture
 * Specification. See also section B.7, table B.8 in the SRP r16a document.
 */
static void srpt_get_svc_entries(u64 ioc_guid,
                                 u16 slot, u8 hi, u8 lo, struct ib_dm_mad *mad)
{
        struct ib_dm_svc_entries *svc_entries;

        WARN_ON(!ioc_guid);

        if (!slot || slot > 16) {
                mad->mad_hdr.status
                        = cpu_to_be16(DM_MAD_STATUS_INVALID_FIELD);
                return;
        }

        if (slot > 2 || lo > hi || hi > 1) {
                mad->mad_hdr.status
                        = cpu_to_be16(DM_MAD_STATUS_NO_IOC);
                return;
        }

        svc_entries = (struct ib_dm_svc_entries *)mad->data;
        memset(svc_entries, 0, sizeof(*svc_entries));
        svc_entries->service_entries[0].id = cpu_to_be64(ioc_guid);
        snprintf(svc_entries->service_entries[0].name,
                 sizeof(svc_entries->service_entries[0].name),
                 "%s%016llx",
                 SRP_SERVICE_NAME_PREFIX,
                 ioc_guid);

        mad->mad_hdr.status = 0;
}

/**
 * srpt_mgmt_method_get() - Process a received management datagram.
 * @sp:      source port through which the MAD has been received.
 * @rq_mad:  received MAD.
 * @rsp_mad: response MAD.
 */
static void srpt_mgmt_method_get(struct srpt_port *sp, struct ib_mad *rq_mad,
                                 struct ib_dm_mad *rsp_mad)
{
        u16 attr_id;
        u32 slot;
        u8 hi, lo;

        attr_id = be16_to_cpu(rq_mad->mad_hdr.attr_id);
        switch (attr_id) {
        case DM_ATTR_CLASS_PORT_INFO:
                srpt_get_class_port_info(rsp_mad);
                break;
        case DM_ATTR_IOU_INFO:
                srpt_get_iou(rsp_mad);
                break;
        case DM_ATTR_IOC_PROFILE:
                slot = be32_to_cpu(rq_mad->mad_hdr.attr_mod);
                srpt_get_ioc(sp, slot, rsp_mad);
                break;
        case DM_ATTR_SVC_ENTRIES:
                slot = be32_to_cpu(rq_mad->mad_hdr.attr_mod);
                hi = (u8) ((slot >> 8) & 0xff);
                lo = (u8) (slot & 0xff);
                slot = (u16) ((slot >> 16) & 0xffff);
                srpt_get_svc_entries(srpt_service_guid,
                                     slot, hi, lo, rsp_mad);
                break;
        default:
                rsp_mad->mad_hdr.status =
                    cpu_to_be16(DM_MAD_STATUS_UNSUP_METHOD_ATTR);
                break;
        }
}

/**
 * srpt_mad_send_handler() - Post MAD-send callback function.
 */
static void srpt_mad_send_handler(struct ib_mad_agent *mad_agent,
                                  struct ib_mad_send_wc *mad_wc)
{
        ib_destroy_ah(mad_wc->send_buf->ah);
        ib_free_send_mad(mad_wc->send_buf);
}

/**
 * srpt_mad_recv_handler() - MAD reception callback function.
 */
static void srpt_mad_recv_handler(struct ib_mad_agent *mad_agent,
                                  struct ib_mad_send_buf *send_buf,
                                  struct ib_mad_recv_wc *mad_wc)
{
        struct srpt_port *sport = (struct srpt_port *)mad_agent->context;
        struct ib_ah *ah;
        struct ib_mad_send_buf *rsp;
        struct ib_dm_mad *dm_mad;

        if (!mad_wc || !mad_wc->recv_buf.mad)
                return;

        ah = ib_create_ah_from_wc(mad_agent->qp->pd, mad_wc->wc,
                                  mad_wc->recv_buf.grh, mad_agent->port_num);
        if (IS_ERR(ah))
                goto err;

        BUILD_BUG_ON(offsetof(struct ib_dm_mad, data) != IB_MGMT_DEVICE_HDR);

        rsp = ib_create_send_mad(mad_agent, mad_wc->wc->src_qp,
                                 mad_wc->wc->pkey_index, 0,
                                 IB_MGMT_DEVICE_HDR, IB_MGMT_DEVICE_DATA,
                                 GFP_KERNEL,
                                 IB_MGMT_BASE_VERSION);
        if (IS_ERR(rsp))
                goto err_rsp;

        rsp->ah = ah;

        dm_mad = rsp->mad;
        memcpy(dm_mad, mad_wc->recv_buf.mad, sizeof(*dm_mad));
        dm_mad->mad_hdr.method = IB_MGMT_METHOD_GET_RESP;
        dm_mad->mad_hdr.status = 0;

        switch (mad_wc->recv_buf.mad->mad_hdr.method) {
        case IB_MGMT_METHOD_GET:
                srpt_mgmt_method_get(sport, mad_wc->recv_buf.mad, dm_mad);
                break;
        case IB_MGMT_METHOD_SET:
                dm_mad->mad_hdr.status =
                    cpu_to_be16(DM_MAD_STATUS_UNSUP_METHOD_ATTR);
                break;
        default:
                dm_mad->mad_hdr.status =
                    cpu_to_be16(DM_MAD_STATUS_UNSUP_METHOD);
                break;
        }

        if (!ib_post_send_mad(rsp, NULL)) {
                ib_free_recv_mad(mad_wc);
                /* will destroy_ah & free_send_mad in send completion */
                return;
        }

        ib_free_send_mad(rsp);

err_rsp:
        ib_destroy_ah(ah);
err:
        ib_free_recv_mad(mad_wc);
}

/**
 * srpt_refresh_port() - Configure a HCA port.
 *
 * Enable InfiniBand management datagram processing, update the cached sm_lid,
 * lid and gid values, and register a callback function for processing MADs
 * on the specified port.
 *
 * Note: It is safe to call this function more than once for the same port.
 */
static int srpt_refresh_port(struct srpt_port *sport)
{
        struct ib_mad_reg_req reg_req;
        struct ib_port_modify port_modify;
        struct ib_port_attr port_attr;
        int ret;

        memset(&port_modify, 0, sizeof(port_modify));
        port_modify.set_port_cap_mask = IB_PORT_DEVICE_MGMT_SUP;
        port_modify.clr_port_cap_mask = 0;

        ret = ib_modify_port(sport->sdev->device, sport->port, 0, &port_modify);
        if (ret)
                goto err_mod_port;

        ret = ib_query_port(sport->sdev->device, sport->port, &port_attr);
        if (ret)
                goto err_query_port;

        sport->sm_lid = port_attr.sm_lid;
        sport->lid = port_attr.lid;

        ret = ib_query_gid(sport->sdev->device, sport->port, 0, &sport->gid,
                           NULL);
        if (ret)
                goto err_query_port;

        snprintf(sport->port_guid, sizeof(sport->port_guid),
                "0x%016llx%016llx",
                be64_to_cpu(sport->gid.global.subnet_prefix),
                be64_to_cpu(sport->gid.global.interface_id));

        if (!sport->mad_agent) {
                memset(&reg_req, 0, sizeof(reg_req));
                reg_req.mgmt_class = IB_MGMT_CLASS_DEVICE_MGMT;
                reg_req.mgmt_class_version = IB_MGMT_BASE_VERSION;
                set_bit(IB_MGMT_METHOD_GET, reg_req.method_mask);
                set_bit(IB_MGMT_METHOD_SET, reg_req.method_mask);

                sport->mad_agent = ib_register_mad_agent(sport->sdev->device,
                                                         sport->port,
                                                         IB_QPT_GSI,
                                                         &reg_req, 0,
                                                         srpt_mad_send_handler,
                                                         srpt_mad_recv_handler,
                                                         sport, 0);
                if (IS_ERR(sport->mad_agent)) {
                        ret = PTR_ERR(sport->mad_agent);
                        sport->mad_agent = NULL;
                        goto err_query_port;
                }
        }

        return 0;

err_query_port:

        port_modify.set_port_cap_mask = 0;
        port_modify.clr_port_cap_mask = IB_PORT_DEVICE_MGMT_SUP;
        ib_modify_port(sport->sdev->device, sport->port, 0, &port_modify);

err_mod_port:

        return ret;
}

/**
 * srpt_unregister_mad_agent() - Unregister MAD callback functions.
 *
 * Note: It is safe to call this function more than once for the same device.
 */
static void srpt_unregister_mad_agent(struct srpt_device *sdev)
{
        struct ib_port_modify port_modify = {
                .clr_port_cap_mask = IB_PORT_DEVICE_MGMT_SUP,
        };
        struct srpt_port *sport;
        int i;

        for (i = 1; i <= sdev->device->phys_port_cnt; i++) {
                sport = &sdev->port[i - 1];
                WARN_ON(sport->port != i);
                if (ib_modify_port(sdev->device, i, 0, &port_modify) < 0)
                        pr_err("disabling MAD processing failed.\n");
                if (sport->mad_agent) {
                        ib_unregister_mad_agent(sport->mad_agent);
                        sport->mad_agent = NULL;
                }
        }
}

/**
 * srpt_alloc_ioctx() - Allocate an SRPT I/O context structure.
 */
static struct srpt_ioctx *srpt_alloc_ioctx(struct srpt_device *sdev,
                                           int ioctx_size, int dma_size,
                                           enum dma_data_direction dir)
{
        struct srpt_ioctx *ioctx;

        ioctx = kmalloc(ioctx_size, GFP_KERNEL);
        if (!ioctx)
                goto err;

        ioctx->buf = kmalloc(dma_size, GFP_KERNEL);
        if (!ioctx->buf)
                goto err_free_ioctx;

        ioctx->dma = ib_dma_map_single(sdev->device, ioctx->buf, dma_size, dir);
        if (ib_dma_mapping_error(sdev->device, ioctx->dma))
                goto err_free_buf;

        return ioctx;

err_free_buf:
        kfree(ioctx->buf);
err_free_ioctx:
        kfree(ioctx);
err:
        return NULL;
}

/**
 * srpt_free_ioctx() - Free an SRPT I/O context structure.
 */
static void srpt_free_ioctx(struct srpt_device *sdev, struct srpt_ioctx *ioctx,
                            int dma_size, enum dma_data_direction dir)
{
        if (!ioctx)
                return;

        ib_dma_unmap_single(sdev->device, ioctx->dma, dma_size, dir);
        kfree(ioctx->buf);
        kfree(ioctx);
}

/**
 * srpt_alloc_ioctx_ring() - Allocate a ring of SRPT I/O context structures.
 * @sdev:       Device to allocate the I/O context ring for.
 * @ring_size:  Number of elements in the I/O context ring.
 * @ioctx_size: I/O context size.
 * @dma_size:   DMA buffer size.
 * @dir:        DMA data direction.
 */
static struct srpt_ioctx **srpt_alloc_ioctx_ring(struct srpt_device *sdev,
                                int ring_size, int ioctx_size,
                                int dma_size, enum dma_data_direction dir)
{
        struct srpt_ioctx **ring;
        int i;

        WARN_ON(ioctx_size != sizeof(struct srpt_recv_ioctx)
                && ioctx_size != sizeof(struct srpt_send_ioctx));

        ring = kmalloc(ring_size * sizeof(ring[0]), GFP_KERNEL);
        if (!ring)
                goto out;
        for (i = 0; i < ring_size; ++i) {
                ring[i] = srpt_alloc_ioctx(sdev, ioctx_size, dma_size, dir);
                if (!ring[i])
                        goto err;
                ring[i]->index = i;
        }
        goto out;

err:
        while (--i >= 0)
                srpt_free_ioctx(sdev, ring[i], dma_size, dir);
        kfree(ring);
        ring = NULL;
out:
        return ring;
}

/**
 * srpt_free_ioctx_ring() - Free the ring of SRPT I/O context structures.
 */
static void srpt_free_ioctx_ring(struct srpt_ioctx **ioctx_ring,
                                 struct srpt_device *sdev, int ring_size,
                                 int dma_size, enum dma_data_direction dir)
{
        int i;

        for (i = 0; i < ring_size; ++i)
                srpt_free_ioctx(sdev, ioctx_ring[i], dma_size, dir);
        kfree(ioctx_ring);
}

/**
 * srpt_get_cmd_state() - Get the state of a SCSI command.
 */
static enum srpt_command_state srpt_get_cmd_state(struct srpt_send_ioctx *ioctx)
{
        enum srpt_command_state state;
        unsigned long flags;

        BUG_ON(!ioctx);

        spin_lock_irqsave(&ioctx->spinlock, flags);
        state = ioctx->state;
        spin_unlock_irqrestore(&ioctx->spinlock, flags);
        return state;
}

/**
 * srpt_set_cmd_state() - Set the state of a SCSI command.
 *
 * Does not modify the state of aborted commands. Returns the previous command
 * state.
 */
static enum srpt_command_state srpt_set_cmd_state(struct srpt_send_ioctx *ioctx,
                                                  enum srpt_command_state new)
{
        enum srpt_command_state previous;
        unsigned long flags;

        BUG_ON(!ioctx);

        spin_lock_irqsave(&ioctx->spinlock, flags);
        previous = ioctx->state;
        if (previous != SRPT_STATE_DONE)
                ioctx->state = new;
        spin_unlock_irqrestore(&ioctx->spinlock, flags);

        return previous;
}

/**
 * srpt_test_and_set_cmd_state() - Test and set the state of a command.
 *
 * Returns true if and only if the previous command state was equal to 'old'.
 */
static bool srpt_test_and_set_cmd_state(struct srpt_send_ioctx *ioctx,
                                        enum srpt_command_state old,
                                        enum srpt_command_state new)
{
        enum srpt_command_state previous;
        unsigned long flags;

        WARN_ON(!ioctx);
        WARN_ON(old == SRPT_STATE_DONE);
        WARN_ON(new == SRPT_STATE_NEW);

        spin_lock_irqsave(&ioctx->spinlock, flags);
        previous = ioctx->state;
        if (previous == old)
                ioctx->state = new;
        spin_unlock_irqrestore(&ioctx->spinlock, flags);
        return previous == old;
}

/**
 * srpt_post_recv() - Post an IB receive request.
 */
static int srpt_post_recv(struct srpt_device *sdev,
                          struct srpt_recv_ioctx *ioctx)
{
        struct ib_sge list;
        struct ib_recv_wr wr, *bad_wr;

        BUG_ON(!sdev);
        list.addr = ioctx->ioctx.dma;
        list.length = srp_max_req_size;
        list.lkey = sdev->pd->local_dma_lkey;

        ioctx->ioctx.cqe.done = srpt_recv_done;
        wr.wr_cqe = &ioctx->ioctx.cqe;
        wr.next = NULL;
        wr.sg_list = &list;
        wr.num_sge = 1;

        return ib_post_srq_recv(sdev->srq, &wr, &bad_wr);
}

/**
 * srpt_zerolength_write() - Perform a zero-length RDMA write.
 *
 * A quote from the InfiniBand specification: C9-88: For an HCA responder
 * using Reliable Connection service, for each zero-length RDMA READ or WRITE
 * request, the R_Key shall not be validated, even if the request includes
 * Immediate data.
 */
static int srpt_zerolength_write(struct srpt_rdma_ch *ch)
{
        struct ib_send_wr wr, *bad_wr;

        memset(&wr, 0, sizeof(wr));
        wr.opcode = IB_WR_RDMA_WRITE;
        wr.wr_cqe = &ch->zw_cqe;
        wr.send_flags = IB_SEND_SIGNALED;
        return ib_post_send(ch->qp, &wr, &bad_wr);
}

static void srpt_zerolength_write_done(struct ib_cq *cq, struct ib_wc *wc)
{
        struct srpt_rdma_ch *ch = cq->cq_context;

        if (wc->status == IB_WC_SUCCESS) {
                srpt_process_wait_list(ch);
        } else {
                if (srpt_set_ch_state(ch, CH_DISCONNECTED))
                        schedule_work(&ch->release_work);
                else
                        WARN_ONCE(1, "%s-%d\n", ch->sess_name, ch->qp->qp_num);
        }
}

static int srpt_alloc_rw_ctxs(struct srpt_send_ioctx *ioctx,
                struct srp_direct_buf *db, int nbufs, struct scatterlist **sg,
                unsigned *sg_cnt)
{
        enum dma_data_direction dir = target_reverse_dma_direction(&ioctx->cmd);
        struct srpt_rdma_ch *ch = ioctx->ch;
        struct scatterlist *prev = NULL;
        unsigned prev_nents;
        int ret, i;

        if (nbufs == 1) {
                ioctx->rw_ctxs = &ioctx->s_rw_ctx;
        } else {
                ioctx->rw_ctxs = kmalloc_array(nbufs, sizeof(*ioctx->rw_ctxs),
                        GFP_KERNEL);
                if (!ioctx->rw_ctxs)
                        return -ENOMEM;
        }

        for (i = ioctx->n_rw_ctx; i < nbufs; i++, db++) {
                struct srpt_rw_ctx *ctx = &ioctx->rw_ctxs[i];
                u64 remote_addr = be64_to_cpu(db->va);
                u32 size = be32_to_cpu(db->len);
                u32 rkey = be32_to_cpu(db->key);

                ret = target_alloc_sgl(&ctx->sg, &ctx->nents, size, false,
                                i < nbufs - 1);
                if (ret)
                        goto unwind;

                ret = rdma_rw_ctx_init(&ctx->rw, ch->qp, ch->sport->port,
                                ctx->sg, ctx->nents, 0, remote_addr, rkey, dir);
                if (ret < 0) {
                        target_free_sgl(ctx->sg, ctx->nents);
                        goto unwind;
                }

                ioctx->n_rdma += ret;
                ioctx->n_rw_ctx++;

                if (prev) {
                        sg_unmark_end(&prev[prev_nents - 1]);
                        sg_chain(prev, prev_nents + 1, ctx->sg);
                } else {
                        *sg = ctx->sg;
                }

                prev = ctx->sg;
                prev_nents = ctx->nents;

                *sg_cnt += ctx->nents;
        }

        return 0;

unwind:
        while (--i >= 0) {
                struct srpt_rw_ctx *ctx = &ioctx->rw_ctxs[i];

                rdma_rw_ctx_destroy(&ctx->rw, ch->qp, ch->sport->port,
                                ctx->sg, ctx->nents, dir);
                target_free_sgl(ctx->sg, ctx->nents);
        }
        if (ioctx->rw_ctxs != &ioctx->s_rw_ctx)
                kfree(ioctx->rw_ctxs);
        return ret;
}

static void srpt_free_rw_ctxs(struct srpt_rdma_ch *ch,
                                    struct srpt_send_ioctx *ioctx)
{
        enum dma_data_direction dir = target_reverse_dma_direction(&ioctx->cmd);
        int i;

        for (i = 0; i < ioctx->n_rw_ctx; i++) {
                struct srpt_rw_ctx *ctx = &ioctx->rw_ctxs[i];

                rdma_rw_ctx_destroy(&ctx->rw, ch->qp, ch->sport->port,
                                ctx->sg, ctx->nents, dir);
                target_free_sgl(ctx->sg, ctx->nents);
        }

        if (ioctx->rw_ctxs != &ioctx->s_rw_ctx)
                kfree(ioctx->rw_ctxs);
}

static inline void *srpt_get_desc_buf(struct srp_cmd *srp_cmd)
{
        /*
         * The pointer computations below will only be compiled correctly
         * if srp_cmd::add_data is declared as s8*, u8*, s8[] or u8[], so check
         * whether srp_cmd::add_data has been declared as a byte pointer.
         */
        BUILD_BUG_ON(!__same_type(srp_cmd->add_data[0], (s8)0) &&
                     !__same_type(srp_cmd->add_data[0], (u8)0));

        /*
         * According to the SRP spec, the lower two bits of the 'ADDITIONAL
         * CDB LENGTH' field are reserved and the size in bytes of this field
         * is four times the value specified in bits 3..7. Hence the "& ~3".
         */
        return srp_cmd->add_data + (srp_cmd->add_cdb_len & ~3);
}

/**
 * srpt_get_desc_tbl() - Parse the data descriptors of an SRP_CMD request.
 * @ioctx: Pointer to the I/O context associated with the request.
 * @srp_cmd: Pointer to the SRP_CMD request data.
 * @dir: Pointer to the variable to which the transfer direction will be
 *   written.
 * @data_len: Pointer to the variable to which the total data length of all
 *   descriptors in the SRP_CMD request will be written.
 *
 * This function initializes ioctx->nrbuf and ioctx->r_bufs.
 *
 * Returns -EINVAL when the SRP_CMD request contains inconsistent descriptors;
 * -ENOMEM when memory allocation fails and zero upon success.
 */
static int srpt_get_desc_tbl(struct srpt_send_ioctx *ioctx,
                struct srp_cmd *srp_cmd, enum dma_data_direction *dir,
                struct scatterlist **sg, unsigned *sg_cnt, u64 *data_len)
{
        BUG_ON(!dir);
        BUG_ON(!data_len);

        /*
         * The lower four bits of the buffer format field contain the DATA-IN
         * buffer descriptor format, and the highest four bits contain the
         * DATA-OUT buffer descriptor format.
         */
        if (srp_cmd->buf_fmt & 0xf)
                /* DATA-IN: transfer data from target to initiator (read). */
                *dir = DMA_FROM_DEVICE;
        else if (srp_cmd->buf_fmt >> 4)
                /* DATA-OUT: transfer data from initiator to target (write). */
                *dir = DMA_TO_DEVICE;
        else
                *dir = DMA_NONE;

        /* initialize data_direction early as srpt_alloc_rw_ctxs needs it */
        ioctx->cmd.data_direction = *dir;

        if (((srp_cmd->buf_fmt & 0xf) == SRP_DATA_DESC_DIRECT) ||
            ((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_DIRECT)) {
                struct srp_direct_buf *db = srpt_get_desc_buf(srp_cmd);

                *data_len = be32_to_cpu(db->len);
                return srpt_alloc_rw_ctxs(ioctx, db, 1, sg, sg_cnt);
        } else if (((srp_cmd->buf_fmt & 0xf) == SRP_DATA_DESC_INDIRECT) ||
                   ((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_INDIRECT)) {
                struct srp_indirect_buf *idb = srpt_get_desc_buf(srp_cmd);
                int nbufs = be32_to_cpu(idb->table_desc.len) /
                                sizeof(struct srp_direct_buf);

                if (nbufs >
                    (srp_cmd->data_out_desc_cnt + srp_cmd->data_in_desc_cnt)) {
                        pr_err("received unsupported SRP_CMD request"
                               " type (%u out + %u in != %u / %zu)\n",
                               srp_cmd->data_out_desc_cnt,
                               srp_cmd->data_in_desc_cnt,
                               be32_to_cpu(idb->table_desc.len),
                               sizeof(struct srp_direct_buf));
                        return -EINVAL;
                }

                *data_len = be32_to_cpu(idb->len);
                return srpt_alloc_rw_ctxs(ioctx, idb->desc_list, nbufs,
                                sg, sg_cnt);
        } else {
                *data_len = 0;
                return 0;
        }
}

/**
 * srpt_init_ch_qp() - Initialize queue pair attributes.
 *
 * Initialized the attributes of queue pair 'qp' by allowing local write,
 * remote read and remote write. Also transitions 'qp' to state IB_QPS_INIT.
 */
static int srpt_init_ch_qp(struct srpt_rdma_ch *ch, struct ib_qp *qp)
{
        struct ib_qp_attr *attr;
        int ret;

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

        attr->qp_state = IB_QPS_INIT;
        attr->qp_access_flags = IB_ACCESS_LOCAL_WRITE | IB_ACCESS_REMOTE_READ |
            IB_ACCESS_REMOTE_WRITE;
        attr->port_num = ch->sport->port;
        attr->pkey_index = 0;

        ret = ib_modify_qp(qp, attr,

                           IB_QP_STATE | IB_QP_ACCESS_FLAGS | IB_QP_PORT |
                           IB_QP_PKEY_INDEX);

        kfree(attr);
        return ret;
}

/**
 * srpt_ch_qp_rtr() - Change the state of a channel to 'ready to receive' (RTR).
 * @ch: channel of the queue pair.
 * @qp: queue pair to change the state of.
 *
 * Returns zero upon success and a negative value upon failure.
 *
 * Note: currently a struct ib_qp_attr takes 136 bytes on a 64-bit system.
 * If this structure ever becomes larger, it might be necessary to allocate
 * it dynamically instead of on the stack.
 */
static int srpt_ch_qp_rtr(struct srpt_rdma_ch *ch, struct ib_qp *qp)
{
        struct ib_qp_attr qp_attr;
        int attr_mask;
        int ret;

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

        qp_attr.max_dest_rd_atomic = 4;

        ret = ib_modify_qp(qp, &qp_attr, attr_mask);

out:
        return ret;
}

/**
 * srpt_ch_qp_rts() - Change the state of a channel to 'ready to send' (RTS).
 * @ch: channel of the queue pair.
 * @qp: queue pair to change the state of.
 *
 * Returns zero upon success and a negative value upon failure.
 *
 * Note: currently a struct ib_qp_attr takes 136 bytes on a 64-bit system.
 * If this structure ever becomes larger, it might be necessary to allocate
 * it dynamically instead of on the stack.
 */
static int srpt_ch_qp_rts(struct srpt_rdma_ch *ch, struct ib_qp *qp)
{
        struct ib_qp_attr qp_attr;
        int attr_mask;
        int ret;

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

        qp_attr.max_rd_atomic = 4;

        ret = ib_modify_qp(qp, &qp_attr, attr_mask);

out:
        return ret;
}

/**
 * srpt_ch_qp_err() - Set the channel queue pair state to 'error'.
 */
static int srpt_ch_qp_err(struct srpt_rdma_ch *ch)
{
        struct ib_qp_attr qp_attr;

        qp_attr.qp_state = IB_QPS_ERR;
        return ib_modify_qp(ch->qp, &qp_attr, IB_QP_STATE);
}

/**
 * srpt_get_send_ioctx() - Obtain an I/O context for sending to the initiator.
 */
static struct srpt_send_ioctx *srpt_get_send_ioctx(struct srpt_rdma_ch *ch)
{
        struct srpt_send_ioctx *ioctx;
        unsigned long flags;

        BUG_ON(!ch);

        ioctx = NULL;
        spin_lock_irqsave(&ch->spinlock, flags);
        if (!list_empty(&ch->free_list)) {
                ioctx = list_first_entry(&ch->free_list,
                                         struct srpt_send_ioctx, free_list);
                list_del(&ioctx->free_list);
        }
        spin_unlock_irqrestore(&ch->spinlock, flags);

        if (!ioctx)
                return ioctx;

        BUG_ON(ioctx->ch != ch);
        spin_lock_init(&ioctx->spinlock);
        ioctx->state = SRPT_STATE_NEW;
        ioctx->n_rdma = 0;
        ioctx->n_rw_ctx = 0;
        init_completion(&ioctx->tx_done);
        ioctx->queue_status_only = false;
        /*
         * transport_init_se_cmd() does not initialize all fields, so do it
         * here.
         */
        memset(&ioctx->cmd, 0, sizeof(ioctx->cmd));
        memset(&ioctx->sense_data, 0, sizeof(ioctx->sense_data));

        return ioctx;
}

/**
 * srpt_abort_cmd() - Abort a SCSI command.
 * @ioctx:   I/O context associated with the SCSI command.
 * @context: Preferred execution context.
 */
static int srpt_abort_cmd(struct srpt_send_ioctx *ioctx)
{
        enum srpt_command_state state;
        unsigned long flags;

        BUG_ON(!ioctx);

        /*
         * If the command is in a state where the target core is waiting for
         * the ib_srpt driver, change the state to the next state.
         */

        spin_lock_irqsave(&ioctx->spinlock, flags);
        state = ioctx->state;
        switch (state) {
        case SRPT_STATE_NEED_DATA:
                ioctx->state = SRPT_STATE_DATA_IN;
                break;
        case SRPT_STATE_CMD_RSP_SENT:
        case SRPT_STATE_MGMT_RSP_SENT:
                ioctx->state = SRPT_STATE_DONE;
                break;
        default:
                WARN_ONCE(true, "%s: unexpected I/O context state %d\n",
                          __func__, state);
                break;
        }
        spin_unlock_irqrestore(&ioctx->spinlock, flags);

        pr_debug("Aborting cmd with state %d and tag %lld\n", state,
                 ioctx->cmd.tag);

        switch (state) {
        case SRPT_STATE_NEW:
        case SRPT_STATE_DATA_IN:
        case SRPT_STATE_MGMT:
        case SRPT_STATE_DONE:
                /*
                 * Do nothing - defer abort processing until
                 * srpt_queue_response() is invoked.
                 */
                break;
        case SRPT_STATE_NEED_DATA:
                pr_debug("tag %#llx: RDMA read error\n", ioctx->cmd.tag);
                transport_generic_request_failure(&ioctx->cmd,
                                        TCM_CHECK_CONDITION_ABORT_CMD);
                break;
        case SRPT_STATE_CMD_RSP_SENT:
                /*
                 * SRP_RSP sending failed or the SRP_RSP send completion has
                 * not been received in time.
                 */
                transport_generic_free_cmd(&ioctx->cmd, 0);
                break;
        case SRPT_STATE_MGMT_RSP_SENT:
                transport_generic_free_cmd(&ioctx->cmd, 0);
                break;
        default:
                WARN(1, "Unexpected command state (%d)", state);
                break;
        }

        return state;
}

/**
 * XXX: what is now target_execute_cmd used to be asynchronous, and unmapping
 * the data that has been transferred via IB RDMA had to be postponed until the
 * check_stop_free() callback.  None of this is necessary anymore and needs to
 * be cleaned up.
 */
static void srpt_rdma_read_done(struct ib_cq *cq, struct ib_wc *wc)
{
        struct srpt_rdma_ch *ch = cq->cq_context;
        struct srpt_send_ioctx *ioctx =
                container_of(wc->wr_cqe, struct srpt_send_ioctx, rdma_cqe);

        WARN_ON(ioctx->n_rdma <= 0);
        atomic_add(ioctx->n_rdma, &ch->sq_wr_avail);
        ioctx->n_rdma = 0;

        if (unlikely(wc->status != IB_WC_SUCCESS)) {
                pr_info("RDMA_READ for ioctx 0x%p failed with status %d\n",
                        ioctx, wc->status);
                srpt_abort_cmd(ioctx);
                return;
        }

        if (srpt_test_and_set_cmd_state(ioctx, SRPT_STATE_NEED_DATA,
                                        SRPT_STATE_DATA_IN))
                target_execute_cmd(&ioctx->cmd);
        else
                pr_err("%s[%d]: wrong state = %d\n", __func__,
                       __LINE__, srpt_get_cmd_state(ioctx));
}

/**
 * srpt_build_cmd_rsp() - Build an SRP_RSP response.
 * @ch: RDMA channel through which the request has been received.
 * @ioctx: I/O context associated with the SRP_CMD request. The response will
 *   be built in the buffer ioctx->buf points at and hence this function will
 *   overwrite the request data.
 * @tag: tag of the request for which this response is being generated.
 * @status: value for the STATUS field of the SRP_RSP information unit.
 *
 * Returns the size in bytes of the SRP_RSP response.
 *
 * An SRP_RSP response contains a SCSI status or service response. See also
 * section 6.9 in the SRP r16a document for the format of an SRP_RSP
 * response. See also SPC-2 for more information about sense data.
 */
static int srpt_build_cmd_rsp(struct srpt_rdma_ch *ch,
                              struct srpt_send_ioctx *ioctx, u64 tag,
                              int status)
{
        struct srp_rsp *srp_rsp;
        const u8 *sense_data;
        int sense_data_len, max_sense_len;

        /*
         * The lowest bit of all SAM-3 status codes is zero (see also
         * paragraph 5.3 in SAM-3).
         */
        WARN_ON(status & 1);

        srp_rsp = ioctx->ioctx.buf;
        BUG_ON(!srp_rsp);

        sense_data = ioctx->sense_data;
        sense_data_len = ioctx->cmd.scsi_sense_length;
        WARN_ON(sense_data_len > sizeof(ioctx->sense_data));

        memset(srp_rsp, 0, sizeof(*srp_rsp));
        srp_rsp->opcode = SRP_RSP;
        srp_rsp->req_lim_delta =
                cpu_to_be32(1 + atomic_xchg(&ch->req_lim_delta, 0));
        srp_rsp->tag = tag;
        srp_rsp->status = status;

        if (sense_data_len) {
                BUILD_BUG_ON(MIN_MAX_RSP_SIZE <= sizeof(*srp_rsp));
                max_sense_len = ch->max_ti_iu_len - sizeof(*srp_rsp);
                if (sense_data_len > max_sense_len) {
                        pr_warn("truncated sense data from %d to %d"
                                " bytes\n", sense_data_len, max_sense_len);
                        sense_data_len = max_sense_len;
                }

                srp_rsp->flags |= SRP_RSP_FLAG_SNSVALID;
                srp_rsp->sense_data_len = cpu_to_be32(sense_data_len);
                memcpy(srp_rsp + 1, sense_data, sense_data_len);
        }

        return sizeof(*srp_rsp) + sense_data_len;
}

/**
 * srpt_build_tskmgmt_rsp() - Build a task management response.
 * @ch:       RDMA channel through which the request has been received.
 * @ioctx:    I/O context in which the SRP_RSP response will be built.
 * @rsp_code: RSP_CODE that will be stored in the response.
 * @tag:      Tag of the request for which this response is being generated.
 *
 * Returns the size in bytes of the SRP_RSP response.
 *
 * An SRP_RSP response contains a SCSI status or service response. See also
 * section 6.9 in the SRP r16a document for the format of an SRP_RSP
 * response.
 */
static int srpt_build_tskmgmt_rsp(struct srpt_rdma_ch *ch,
                                  struct srpt_send_ioctx *ioctx,
                                  u8 rsp_code, u64 tag)
{
        struct srp_rsp *srp_rsp;
        int resp_data_len;
        int resp_len;

        resp_data_len = 4;
        resp_len = sizeof(*srp_rsp) + resp_data_len;

        srp_rsp = ioctx->ioctx.buf;
        BUG_ON(!srp_rsp);
        memset(srp_rsp, 0, sizeof(*srp_rsp));

        srp_rsp->opcode = SRP_RSP;
        srp_rsp->req_lim_delta =
                cpu_to_be32(1 + atomic_xchg(&ch->req_lim_delta, 0));
        srp_rsp->tag = tag;

        srp_rsp->flags |= SRP_RSP_FLAG_RSPVALID;
        srp_rsp->resp_data_len = cpu_to_be32(resp_data_len);
        srp_rsp->data[3] = rsp_code;

        return resp_len;
}

static int srpt_check_stop_free(struct se_cmd *cmd)
{
        struct srpt_send_ioctx *ioctx = container_of(cmd,
                                struct srpt_send_ioctx, cmd);

        return target_put_sess_cmd(&ioctx->cmd);
}

/**
 * srpt_handle_cmd() - Process SRP_CMD.
 */
static void srpt_handle_cmd(struct srpt_rdma_ch *ch,
                            struct srpt_recv_ioctx *recv_ioctx,
                            struct srpt_send_ioctx *send_ioctx)
{
        struct se_cmd *cmd;
        struct srp_cmd *srp_cmd;
        struct scatterlist *sg = NULL;
        unsigned sg_cnt = 0;
        u64 data_len;
        enum dma_data_direction dir;
        int rc;

        BUG_ON(!send_ioctx);

        srp_cmd = recv_ioctx->ioctx.buf;
        cmd = &send_ioctx->cmd;
        cmd->tag = srp_cmd->tag;

        switch (srp_cmd->task_attr) {
        case SRP_CMD_SIMPLE_Q:
                cmd->sam_task_attr = TCM_SIMPLE_TAG;
                break;
        case SRP_CMD_ORDERED_Q:
        default:
                cmd->sam_task_attr = TCM_ORDERED_TAG;
                break;
        case SRP_CMD_HEAD_OF_Q:
                cmd->sam_task_attr = TCM_HEAD_TAG;
                break;
        case SRP_CMD_ACA:
                cmd->sam_task_attr = TCM_ACA_TAG;
                break;
        }

        rc = srpt_get_desc_tbl(send_ioctx, srp_cmd, &dir, &sg, &sg_cnt,
                        &data_len);
        if (rc) {
                if (rc != -EAGAIN) {
                        pr_err("0x%llx: parsing SRP descriptor table failed.\n",
                               srp_cmd->tag);
                }
                goto release_ioctx;
        }

        rc = target_submit_cmd_map_sgls(cmd, ch->sess, srp_cmd->cdb,
                               &send_ioctx->sense_data[0],
                               scsilun_to_int(&srp_cmd->lun), data_len,
                               TCM_SIMPLE_TAG, dir, TARGET_SCF_ACK_KREF,
                               sg, sg_cnt, NULL, 0, NULL, 0);
        if (rc != 0) {
                pr_debug("target_submit_cmd() returned %d for tag %#llx\n", rc,
                         srp_cmd->tag);
                goto release_ioctx;
        }
        return;

release_ioctx:
        send_ioctx->state = SRPT_STATE_DONE;
        srpt_release_cmd(cmd);
}

static int srp_tmr_to_tcm(int fn)
{
        switch (fn) {
        case SRP_TSK_ABORT_TASK:
                return TMR_ABORT_TASK;
        case SRP_TSK_ABORT_TASK_SET:
                return TMR_ABORT_TASK_SET;
        case SRP_TSK_CLEAR_TASK_SET:
                return TMR_CLEAR_TASK_SET;
        case SRP_TSK_LUN_RESET:
                return TMR_LUN_RESET;
        case SRP_TSK_CLEAR_ACA:
                return TMR_CLEAR_ACA;
        default:
                return -1;
        }
}

/**
 * srpt_handle_tsk_mgmt() - Process an SRP_TSK_MGMT information unit.
 *
 * Returns 0 if and only if the request will be processed by the target core.
 *
 * For more information about SRP_TSK_MGMT information units, see also section
 * 6.7 in the SRP r16a document.
 */
static void srpt_handle_tsk_mgmt(struct srpt_rdma_ch *ch,
                                 struct srpt_recv_ioctx *recv_ioctx,
                                 struct srpt_send_ioctx *send_ioctx)
{
        struct srp_tsk_mgmt *srp_tsk;
        struct se_cmd *cmd;
        struct se_session *sess = ch->sess;
        int tcm_tmr;
        int rc;

        BUG_ON(!send_ioctx);

        srp_tsk = recv_ioctx->ioctx.buf;
        cmd = &send_ioctx->cmd;

        pr_debug("recv tsk_mgmt fn %d for task_tag %lld and cmd tag %lld"
                 " cm_id %p sess %p\n", srp_tsk->tsk_mgmt_func,
                 srp_tsk->task_tag, srp_tsk->tag, ch->cm_id, ch->sess);

        srpt_set_cmd_state(send_ioctx, SRPT_STATE_MGMT);
        send_ioctx->cmd.tag = srp_tsk->tag;
        tcm_tmr = srp_tmr_to_tcm(srp_tsk->tsk_mgmt_func);
        rc = target_submit_tmr(&send_ioctx->cmd, sess, NULL,
                               scsilun_to_int(&srp_tsk->lun), srp_tsk, tcm_tmr,
                               GFP_KERNEL, srp_tsk->task_tag,
                               TARGET_SCF_ACK_KREF);
        if (rc != 0) {
                send_ioctx->cmd.se_tmr_req->response = TMR_FUNCTION_REJECTED;
                goto fail;
        }
        return;
fail:
        transport_send_check_condition_and_sense(cmd, 0, 0); // XXX:
}

/**
 * srpt_handle_new_iu() - Process a newly received information unit.
 * @ch:    RDMA channel through which the information unit has been received.
 * @ioctx: SRPT I/O context associated with the information unit.
 */
static void srpt_handle_new_iu(struct srpt_rdma_ch *ch,
                               struct srpt_recv_ioctx *recv_ioctx,
                               struct srpt_send_ioctx *send_ioctx)
{
        struct srp_cmd *srp_cmd;

        BUG_ON(!ch);
        BUG_ON(!recv_ioctx);

        ib_dma_sync_single_for_cpu(ch->sport->sdev->device,
                                   recv_ioctx->ioctx.dma, srp_max_req_size,
                                   DMA_FROM_DEVICE);

        if (unlikely(ch->state == CH_CONNECTING))
                goto out_wait;

        if (unlikely(ch->state != CH_LIVE))
                return;

        srp_cmd = recv_ioctx->ioctx.buf;
        if (srp_cmd->opcode == SRP_CMD || srp_cmd->opcode == SRP_TSK_MGMT) {
                if (!send_ioctx) {
                        if (!list_empty(&ch->cmd_wait_list))
                                goto out_wait;
                        send_ioctx = srpt_get_send_ioctx(ch);
                }
                if (unlikely(!send_ioctx))
                        goto out_wait;
        }

        switch (srp_cmd->opcode) {
        case SRP_CMD:
                srpt_handle_cmd(ch, recv_ioctx, send_ioctx);
                break;
        case SRP_TSK_MGMT:
                srpt_handle_tsk_mgmt(ch, recv_ioctx, send_ioctx);
                break;
        case SRP_I_LOGOUT:
                pr_err("Not yet implemented: SRP_I_LOGOUT\n");
                break;
        case SRP_CRED_RSP:
                pr_debug("received SRP_CRED_RSP\n");
                break;
        case SRP_AER_RSP:
                pr_debug("received SRP_AER_RSP\n");
                break;
        case SRP_RSP:
                pr_err("Received SRP_RSP\n");
                break;
        default:
                pr_err("received IU with unknown opcode 0x%x\n",
                       srp_cmd->opcode);
                break;
        }

        srpt_post_recv(ch->sport->sdev, recv_ioctx);
        return;

out_wait:
        list_add_tail(&recv_ioctx->wait_list, &ch->cmd_wait_list);
}

static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc)
{
        struct srpt_rdma_ch *ch = cq->cq_context;
        struct srpt_recv_ioctx *ioctx =
                container_of(wc->wr_cqe, struct srpt_recv_ioctx, ioctx.cqe);

        if (wc->status == IB_WC_SUCCESS) {
                int req_lim;

                req_lim = atomic_dec_return(&ch->req_lim);
                if (unlikely(req_lim < 0))
                        pr_err("req_lim = %d < 0\n", req_lim);
                srpt_handle_new_iu(ch, ioctx, NULL);
        } else {
                pr_info("receiving failed for ioctx %p with status %d\n",
                        ioctx, wc->status);
        }
}

/*
 * This function must be called from the context in which RDMA completions are
 * processed because it accesses the wait list without protection against
 * access from other threads.
 */
static void srpt_process_wait_list(struct srpt_rdma_ch *ch)
{
        struct srpt_send_ioctx *ioctx;

        while (!list_empty(&ch->cmd_wait_list) &&
               ch->state >= CH_LIVE &&
               (ioctx = srpt_get_send_ioctx(ch)) != NULL) {
                struct srpt_recv_ioctx *recv_ioctx;

                recv_ioctx = list_first_entry(&ch->cmd_wait_list,
                                              struct srpt_recv_ioctx,
                                              wait_list);
                list_del(&recv_ioctx->wait_list);
                srpt_handle_new_iu(ch, recv_ioctx, ioctx);
        }
}

/**
 * Note: Although this has not yet been observed during tests, at least in
 * theory it is possible that the srpt_get_send_ioctx() call invoked by
 * srpt_handle_new_iu() fails. This is possible because the req_lim_delta
 * value in each response is set to one, and it is possible that this response
 * makes the initiator send a new request before the send completion for that
 * response has been processed. This could e.g. happen if the call to
 * srpt_put_send_iotcx() is delayed because of a higher priority interrupt or
 * if IB retransmission causes generation of the send completion to be
 * delayed. Incoming information units for which srpt_get_send_ioctx() fails
 * are queued on cmd_wait_list. The code below processes these delayed
 * requests one at a time.
 */
static void srpt_send_done(struct ib_cq *cq, struct ib_wc *wc)
{
        struct srpt_rdma_ch *ch = cq->cq_context;
        struct srpt_send_ioctx *ioctx =
                container_of(wc->wr_cqe, struct srpt_send_ioctx, ioctx.cqe);
        enum srpt_command_state state;

        state = srpt_set_cmd_state(ioctx, SRPT_STATE_DONE);

        WARN_ON(state != SRPT_STATE_CMD_RSP_SENT &&
                state != SRPT_STATE_MGMT_RSP_SENT);

        atomic_add(1 + ioctx->n_rdma, &ch->sq_wr_avail);

        if (wc->status != IB_WC_SUCCESS)
                pr_info("sending response for ioctx 0x%p failed"
                        " with status %d\n", ioctx, wc->status);

        if (state != SRPT_STATE_DONE) {
                transport_generic_free_cmd(&ioctx->cmd, 0);
        } else {
                pr_err("IB completion has been received too late for"
                       " wr_id = %u.\n", ioctx->ioctx.index);
        }

        srpt_process_wait_list(ch);
}

/**
 * srpt_create_ch_ib() - Create receive and send completion queues.
 */
static int srpt_create_ch_ib(struct srpt_rdma_ch *ch)
{
        struct ib_qp_init_attr *qp_init;
        struct srpt_port *sport = ch->sport;
        struct srpt_device *sdev = sport->sdev;
        const struct ib_device_attr *attrs = &sdev->device->attrs;
        u32 srp_sq_size = sport->port_attrib.srp_sq_size;
        int ret;

        WARN_ON(ch->rq_size < 1);

        ret = -ENOMEM;
        qp_init = kzalloc(sizeof(*qp_init), GFP_KERNEL);
        if (!qp_init)
                goto out;

retry:
        ch->cq = ib_alloc_cq(sdev->device, ch, ch->rq_size + srp_sq_size,
                        0 /* XXX: spread CQs */, IB_POLL_WORKQUEUE);
        if (IS_ERR(ch->cq)) {
                ret = PTR_ERR(ch->cq);
                pr_err("failed to create CQ cqe= %d ret= %d\n",
                       ch->rq_size + srp_sq_size, ret);
                goto out;
        }

        qp_init->qp_context = (void *)ch;
        qp_init->event_handler
                = (void(*)(struct ib_event *, void*))srpt_qp_event;
        qp_init->send_cq = ch->cq;
        qp_init->recv_cq = ch->cq;
        qp_init->srq = sdev->srq;
        qp_init->sq_sig_type = IB_SIGNAL_REQ_WR;
        qp_init->qp_type = IB_QPT_RC;
        /*
         * We divide up our send queue size into half SEND WRs to send the
         * completions, and half R/W contexts to actually do the RDMA
         * READ/WRITE transfers.  Note that we need to allocate CQ slots for
         * both both, as RDMA contexts will also post completions for the
         * RDMA READ case.
         */
        qp_init->cap.max_send_wr = srp_sq_size / 2;
        qp_init->cap.max_rdma_ctxs = srp_sq_size / 2;
        qp_init->cap.max_send_sge = min(attrs->max_sge, SRPT_MAX_SG_PER_WQE);
        qp_init->port_num = ch->sport->port;

        ch->qp = ib_create_qp(sdev->pd, qp_init);
        if (IS_ERR(ch->qp)) {
                ret = PTR_ERR(ch->qp);
                if (ret == -ENOMEM) {
                        srp_sq_size /= 2;
                        if (srp_sq_size >= MIN_SRPT_SQ_SIZE) {
                                ib_destroy_cq(ch->cq);
                                goto retry;
                        }
                }
                pr_err("failed to create_qp ret= %d\n", ret);
                goto err_destroy_cq;
        }

        atomic_set(&ch->sq_wr_avail, qp_init->cap.max_send_wr);

        pr_debug("%s: max_cqe= %d max_sge= %d sq_size = %d cm_id= %p\n",
                 __func__, ch->cq->cqe, qp_init->cap.max_send_sge,
                 qp_init->cap.max_send_wr, ch->cm_id);

        ret = srpt_init_ch_qp(ch, ch->qp);
        if (ret)
                goto err_destroy_qp;

out:
        kfree(qp_init);
        return ret;

err_destroy_qp:
        ib_destroy_qp(ch->qp);
err_destroy_cq:
        ib_free_cq(ch->cq);
        goto out;
}

static void srpt_destroy_ch_ib(struct srpt_rdma_ch *ch)
{
        ib_destroy_qp(ch->qp);
        ib_free_cq(ch->cq);
}

/**
 * srpt_close_ch() - Close an RDMA channel.
 *
 * Make sure all resources associated with the channel will be deallocated at
 * an appropriate time.
 *
 * Returns true if and only if the channel state has been modified into
 * CH_DRAINING.
 */
static bool srpt_close_ch(struct srpt_rdma_ch *ch)
{
        int ret;

        if (!srpt_set_ch_state(ch, CH_DRAINING)) {
                pr_debug("%s-%d: already closed\n", ch->sess_name,
                         ch->qp->qp_num);
                return false;
        }

        kref_get(&ch->kref);

        ret = srpt_ch_qp_err(ch);
        if (ret < 0)
                pr_err("%s-%d: changing queue pair into error state failed: %d\n",
                       ch->sess_name, ch->qp->qp_num, ret);

        pr_debug("%s-%d: queued zerolength write\n", ch->sess_name,
                 ch->qp->qp_num);
        ret = srpt_zerolength_write(ch);
        if (ret < 0) {
                pr_err("%s-%d: queuing zero-length write failed: %d\n",
                       ch->sess_name, ch->qp->qp_num, ret);
                if (srpt_set_ch_state(ch, CH_DISCONNECTED))
                        schedule_work(&ch->release_work);
                else
                        WARN_ON_ONCE(true);
        }

        kref_put(&ch->kref, srpt_free_ch);

        return true;
}

/*
 * Change the channel state into CH_DISCONNECTING. If a channel has not yet
 * reached the connected state, close it. If a channel is in the connected
 * state, send a DREQ. If a DREQ has been received, send a DREP. Note: it is
 * the responsibility of the caller to ensure that this function is not
 * invoked concurrently with the code that accepts a connection. This means
 * that this function must either be invoked from inside a CM callback
 * function or that it must be invoked with the srpt_port.mutex held.
 */
static int srpt_disconnect_ch(struct srpt_rdma_ch *ch)
{
        int ret;

        if (!srpt_set_ch_state(ch, CH_DISCONNECTING))
                return -ENOTCONN;

        ret = ib_send_cm_dreq(ch->cm_id, NULL, 0);
        if (ret < 0)
                ret = ib_send_cm_drep(ch->cm_id, NULL, 0);

        if (ret < 0 && srpt_close_ch(ch))
                ret = 0;

        return ret;
}

static void __srpt_close_all_ch(struct srpt_device *sdev)
{
        struct srpt_rdma_ch *ch;

        lockdep_assert_held(&sdev->mutex);

        list_for_each_entry(ch, &sdev->rch_list, list) {
                if (srpt_disconnect_ch(ch) >= 0)
                        pr_info("Closing channel %s-%d because target %s has been disabled\n",
                                ch->sess_name, ch->qp->qp_num,
                                sdev->device->name);
                srpt_close_ch(ch);
        }
}

static void srpt_free_ch(struct kref *kref)
{
        struct srpt_rdma_ch *ch = container_of(kref, struct srpt_rdma_ch, kref);

        kfree(ch);
}

static void srpt_release_channel_work(struct work_struct *w)
{
        struct srpt_rdma_ch *ch;
        struct srpt_device *sdev;
        struct se_session *se_sess;

        ch = container_of(w, struct srpt_rdma_ch, release_work);
        pr_debug("%s: %s-%d; release_done = %p\n", __func__, ch->sess_name,
                 ch->qp->qp_num, ch->release_done);

        sdev = ch->sport->sdev;
        BUG_ON(!sdev);

        se_sess = ch->sess;
        BUG_ON(!se_sess);

        target_sess_cmd_list_set_waiting(se_sess);
        target_wait_for_sess_cmds(se_sess);

        transport_deregister_session_configfs(se_sess);
        transport_deregister_session(se_sess);
        ch->sess = NULL;

        ib_destroy_cm_id(ch->cm_id);

        srpt_destroy_ch_ib(ch);

        srpt_free_ioctx_ring((struct srpt_ioctx **)ch->ioctx_ring,
                             ch->sport->sdev, ch->rq_size,
                             ch->rsp_size, DMA_TO_DEVICE);

        mutex_lock(&sdev->mutex);
        list_del_init(&ch->list);
        if (ch->release_done)
                complete(ch->release_done);
        mutex_unlock(&sdev->mutex);

        wake_up(&sdev->ch_releaseQ);

        kref_put(&ch->kref, srpt_free_ch);
}

/**
 * srpt_cm_req_recv() - Process the event IB_CM_REQ_RECEIVED.
 *
 * Ownership of the cm_id is transferred to the target session if this
 * functions returns zero. Otherwise the caller remains the owner of cm_id.
 */
static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
                            struct ib_cm_req_event_param *param,
                            void *private_data)
{
        struct srpt_device *sdev = cm_id->context;
        struct srpt_port *sport = &sdev->port[param->port - 1];
        struct srp_login_req *req;
        struct srp_login_rsp *rsp;
        struct srp_login_rej *rej;
        struct ib_cm_rep_param *rep_param;
        struct srpt_rdma_ch *ch, *tmp_ch;
        u32 it_iu_len;
        int i, ret = 0;
        unsigned char *p;

        WARN_ON_ONCE(irqs_disabled());

        if (WARN_ON(!sdev || !private_data))
                return -EINVAL;

        req = (struct srp_login_req *)private_data;

        it_iu_len = be32_to_cpu(req->req_it_iu_len);

        pr_info("Received SRP_LOGIN_REQ with i_port_id 0x%llx:0x%llx,"
                " t_port_id 0x%llx:0x%llx and it_iu_len %d on port %d"
                " (guid=0x%llx:0x%llx)\n",
                be64_to_cpu(*(__be64 *)&req->initiator_port_id[0]),
                be64_to_cpu(*(__be64 *)&req->initiator_port_id[8]),
                be64_to_cpu(*(__be64 *)&req->target_port_id[0]),
                be64_to_cpu(*(__be64 *)&req->target_port_id[8]),
                it_iu_len,
                param->port,
                be64_to_cpu(*(__be64 *)&sdev->port[param->port - 1].gid.raw[0]),
                be64_to_cpu(*(__be64 *)&sdev->port[param->port - 1].gid.raw[8]));

        rsp = kzalloc(sizeof(*rsp), GFP_KERNEL);
        rej = kzalloc(sizeof(*rej), GFP_KERNEL);
        rep_param = kzalloc(sizeof(*rep_param), GFP_KERNEL);

        if (!rsp || !rej || !rep_param) {
                ret = -ENOMEM;
                goto out;
        }

        if (it_iu_len > srp_max_req_size || it_iu_len < 64) {
                rej->reason = cpu_to_be32(
                              SRP_LOGIN_REJ_REQ_IT_IU_LENGTH_TOO_LARGE);
                ret = -EINVAL;
                pr_err("rejected SRP_LOGIN_REQ because its"
                       " length (%d bytes) is out of range (%d .. %d)\n",
                       it_iu_len, 64, srp_max_req_size);
                goto reject;
        }

        if (!sport->enabled) {
                rej->reason = cpu_to_be32(
                              SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
                ret = -EINVAL;
                pr_err("rejected SRP_LOGIN_REQ because the target port"
                       " has not yet been enabled\n");
                goto reject;
        }

        if ((req->req_flags & SRP_MTCH_ACTION) == SRP_MULTICHAN_SINGLE) {
                rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_NO_CHAN;

                mutex_lock(&sdev->mutex);

                list_for_each_entry_safe(ch, tmp_ch, &sdev->rch_list, list) {
                        if (!memcmp(ch->i_port_id, req->initiator_port_id, 16)
                            && !memcmp(ch->t_port_id, req->target_port_id, 16)
                            && param->port == ch->sport->port
                            && param->listen_id == ch->sport->sdev->cm_id
                            && ch->cm_id) {
                                if (srpt_disconnect_ch(ch) < 0)
                                        continue;
                                pr_info("Relogin - closed existing channel %s\n",
                                        ch->sess_name);
                                rsp->rsp_flags =
                                        SRP_LOGIN_RSP_MULTICHAN_TERMINATED;
                        }
                }

                mutex_unlock(&sdev->mutex);

        } else
                rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_MAINTAINED;

        if (*(__be64 *)req->target_port_id != cpu_to_be64(srpt_service_guid)
            || *(__be64 *)(req->target_port_id + 8) !=
               cpu_to_be64(srpt_service_guid)) {
                rej->reason = cpu_to_be32(
                              SRP_LOGIN_REJ_UNABLE_ASSOCIATE_CHANNEL);
                ret = -ENOMEM;
                pr_err("rejected SRP_LOGIN_REQ because it"
                       " has an invalid target port identifier.\n");
                goto reject;
        }

        ch = kzalloc(sizeof(*ch), GFP_KERNEL);
        if (!ch) {
                rej->reason = cpu_to_be32(
                              SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
                pr_err("rejected SRP_LOGIN_REQ because no memory.\n");
                ret = -ENOMEM;
                goto reject;
        }

        kref_init(&ch->kref);
        ch->zw_cqe.done = srpt_zerolength_write_done;
        INIT_WORK(&ch->release_work, srpt_release_channel_work);
        memcpy(ch->i_port_id, req->initiator_port_id, 16);
        memcpy(ch->t_port_id, req->target_port_id, 16);
        ch->sport = &sdev->port[param->port - 1];
        ch->cm_id = cm_id;
        cm_id->context = ch;
        /*
         * Avoid QUEUE_FULL conditions by limiting the number of buffers used
         * for the SRP protocol to the command queue size.
         */
        ch->rq_size = SRPT_RQ_SIZE;
        spin_lock_init(&ch->spinlock);
        ch->state = CH_CONNECTING;
        INIT_LIST_HEAD(&ch->cmd_wait_list);
        ch->rsp_size = ch->sport->port_attrib.srp_max_rsp_size;

        ch->ioctx_ring = (struct srpt_send_ioctx **)
                srpt_alloc_ioctx_ring(ch->sport->sdev, ch->rq_size,
                                      sizeof(*ch->ioctx_ring[0]),
                                      ch->rsp_size, DMA_TO_DEVICE);
        if (!ch->ioctx_ring)
                goto free_ch;

        INIT_LIST_HEAD(&ch->free_list);
        for (i = 0; i < ch->rq_size; i++) {
                ch->ioctx_ring[i]->ch = ch;
                list_add_tail(&ch->ioctx_ring[i]->free_list, &ch->free_list);
        }

        ret = srpt_create_ch_ib(ch);
        if (ret) {
                rej->reason = cpu_to_be32(
                              SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
                pr_err("rejected SRP_LOGIN_REQ because creating"
                       " a new RDMA channel failed.\n");
                goto free_ring;
        }

        ret = srpt_ch_qp_rtr(ch, ch->qp);
        if (ret) {
                rej->reason = cpu_to_be32(SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
                pr_err("rejected SRP_LOGIN_REQ because enabling"
                       " RTR failed (error code = %d)\n", ret);
                goto destroy_ib;
        }

        /*
         * Use the initator port identifier as the session name, when
         * checking against se_node_acl->initiatorname[] this can be
         * with or without preceeding '0x'.
         */
        snprintf(ch->sess_name, sizeof(ch->sess_name), "0x%016llx%016llx",
                        be64_to_cpu(*(__be64 *)ch->i_port_id),
                        be64_to_cpu(*(__be64 *)(ch->i_port_id + 8)));

        pr_debug("registering session %s\n", ch->sess_name);
        p = &ch->sess_name[0];

try_again:
        ch->sess = target_alloc_session(&sport->port_tpg_1, 0, 0,

                                        TARGET_PROT_NORMAL, p, ch, NULL);
        if (IS_ERR(ch->sess)) {
                pr_info("Rejected login because no ACL has been"
                        " configured yet for initiator %s.\n", p);
                /*
                 * XXX: Hack to retry of ch->i_port_id without leading '0x'
                 */
                if (p == &ch->sess_name[0]) {
                        p += 2;
                        goto try_again;
                }
                rej->reason = cpu_to_be32((PTR_ERR(ch->sess) == -ENOMEM) ?
                                SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES :
                                SRP_LOGIN_REJ_CHANNEL_LIMIT_REACHED);
                goto destroy_ib;
        }

        pr_debug("Establish connection sess=%p name=%s cm_id=%p\n", ch->sess,
                 ch->sess_name, ch->cm_id);

        /* create srp_login_response */
        rsp->opcode = SRP_LOGIN_RSP;
        rsp->tag = req->tag;
        rsp->max_it_iu_len = req->req_it_iu_len;
        rsp->max_ti_iu_len = req->req_it_iu_len;
        ch->max_ti_iu_len = it_iu_len;
        rsp->buf_fmt = cpu_to_be16(SRP_BUF_FORMAT_DIRECT
                                   | SRP_BUF_FORMAT_INDIRECT);
        rsp->req_lim_delta = cpu_to_be32(ch->rq_size);
        atomic_set(&ch->req_lim, ch->rq_size);
        atomic_set(&ch->req_lim_delta, 0);

        /* create cm reply */
        rep_param->qp_num = ch->qp->qp_num;
        rep_param->private_data = (void *)rsp;
        rep_param->private_data_len = sizeof(*rsp);
        rep_param->rnr_retry_count = 7;
        rep_param->flow_control = 1;
        rep_param->failover_accepted = 0;
        rep_param->srq = 1;
        rep_param->responder_resources = 4;
        rep_param->initiator_depth = 4;

        ret = ib_send_cm_rep(cm_id, rep_param);
        if (ret) {
                pr_err("sending SRP_LOGIN_REQ response failed"
                       " (error code = %d)\n", ret);
                goto release_channel;
        }

        mutex_lock(&sdev->mutex);
        list_add_tail(&ch->list, &sdev->rch_list);
        mutex_unlock(&sdev->mutex);

        goto out;

release_channel:
        srpt_disconnect_ch(ch);
        transport_deregister_session_configfs(ch->sess);
        transport_deregister_session(ch->sess);
        ch->sess = NULL;

destroy_ib:
        srpt_destroy_ch_ib(ch);

free_ring:
        srpt_free_ioctx_ring((struct srpt_ioctx **)ch->ioctx_ring,
                             ch->sport->sdev, ch->rq_size,
                             ch->rsp_size, DMA_TO_DEVICE);
free_ch:
        kfree(ch);

reject:
        rej->opcode = SRP_LOGIN_REJ;
        rej->tag = req->tag;
        rej->buf_fmt = cpu_to_be16(SRP_BUF_FORMAT_DIRECT
                                   | SRP_BUF_FORMAT_INDIRECT);

        ib_send_cm_rej(cm_id, IB_CM_REJ_CONSUMER_DEFINED, NULL, 0,
                             (void *)rej, sizeof(*rej));

out:
        kfree(rep_param);
        kfree(rsp);
        kfree(rej);

        return ret;
}

static void srpt_cm_rej_recv(struct srpt_rdma_ch *ch,
                             enum ib_cm_rej_reason reason,
                             const u8 *private_data,
                             u8 private_data_len)
{
        char *priv = NULL;
        int i;

        if (private_data_len && (priv = kmalloc(private_data_len * 3 + 1,
                                                GFP_KERNEL))) {
                for (i = 0; i < private_data_len; i++)
                        sprintf(priv + 3 * i, " %02x", private_data[i]);
        }
        pr_info("Received CM REJ for ch %s-%d; reason %d%s%s.\n",
                ch->sess_name, ch->qp->qp_num, reason, private_data_len ?
                "; private data" : "", priv ? priv : " (?)");
        kfree(priv);
}

/**
 * srpt_cm_rtu_recv() - Process an IB_CM_RTU_RECEIVED or USER_ESTABLISHED event.
 *
 * An IB_CM_RTU_RECEIVED message indicates that the connection is established
 * and that the recipient may begin transmitting (RTU = ready to use).
 */
static void srpt_cm_rtu_recv(struct srpt_rdma_ch *ch)
{
        int ret;

        if (srpt_set_ch_state(ch, CH_LIVE)) {
                ret = srpt_ch_qp_rts(ch, ch->qp);

                if (ret == 0) {
                        /* Trigger wait list processing. */
                        ret = srpt_zerolength_write(ch);
                        WARN_ONCE(ret < 0, "%d\n", ret);
                } else {
                        srpt_close_ch(ch);
                }
        }
}

/**
 * srpt_cm_handler() - IB connection manager callback function.
 *
 * A non-zero return value will cause the caller destroy the CM ID.
 *
 * Note: srpt_cm_handler() must only return a non-zero value when transferring
 * ownership of the cm_id to a channel by srpt_cm_req_recv() failed. Returning
 * a non-zero value in any other case will trigger a race with the
 * ib_destroy_cm_id() call in srpt_release_channel().
 */
static int srpt_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
{
        struct srpt_rdma_ch *ch = cm_id->context;
        int ret;

        ret = 0;
        switch (event->event) {
        case IB_CM_REQ_RECEIVED:
                ret = srpt_cm_req_recv(cm_id, &event->param.req_rcvd,
                                       event->private_data);
                break;
        case IB_CM_REJ_RECEIVED:
                srpt_cm_rej_recv(ch, event->param.rej_rcvd.reason,
                                 event->private_data,
                                 IB_CM_REJ_PRIVATE_DATA_SIZE);
                break;
        case IB_CM_RTU_RECEIVED:
        case IB_CM_USER_ESTABLISHED:
                srpt_cm_rtu_recv(ch);
                break;
        case IB_CM_DREQ_RECEIVED:
                srpt_disconnect_ch(ch);
                break;
        case IB_CM_DREP_RECEIVED:
                pr_info("Received CM DREP message for ch %s-%d.\n",
                        ch->sess_name, ch->qp->qp_num);
                srpt_close_ch(ch);
                break;
        case IB_CM_TIMEWAIT_EXIT:
                pr_info("Received CM TimeWait exit for ch %s-%d.\n",
                        ch->sess_name, ch->qp->qp_num);
                srpt_close_ch(ch);
                break;
        case IB_CM_REP_ERROR:
                pr_info("Received CM REP error for ch %s-%d.\n", ch->sess_name,
                        ch->qp->qp_num);
                break;
        case IB_CM_DREQ_ERROR:
                pr_info("Received CM DREQ ERROR event.\n");
                break;
        case IB_CM_MRA_RECEIVED:
                pr_info("Received CM MRA event\n");
                break;
        default:
                pr_err("received unrecognized CM event %d\n", event->event);
                break;
        }

        return ret;
}

static int srpt_write_pending_status(struct se_cmd *se_cmd)
{
        struct srpt_send_ioctx *ioctx;

        ioctx = container_of(se_cmd, struct srpt_send_ioctx, cmd);
        return srpt_get_cmd_state(ioctx) == SRPT_STATE_NEED_DATA;
}

/*
 * srpt_write_pending() - Start data transfer from initiator to target (write).
 */
static int srpt_write_pending(struct se_cmd *se_cmd)
{
        struct srpt_send_ioctx *ioctx =
                container_of(se_cmd, struct srpt_send_ioctx, cmd);
        struct srpt_rdma_ch *ch = ioctx->ch;
        struct ib_send_wr *first_wr = NULL, *bad_wr;
        struct ib_cqe *cqe = &ioctx->rdma_cqe;
        enum srpt_command_state new_state;
        int ret, i;

        new_state = srpt_set_cmd_state(ioctx, SRPT_STATE_NEED_DATA);
        WARN_ON(new_state == SRPT_STATE_DONE);

        if (atomic_sub_return(ioctx->n_rdma, &ch->sq_wr_avail) < 0) {
                pr_warn("%s: IB send queue full (needed %d)\n",
                                __func__, ioctx->n_rdma);
                ret = -ENOMEM;
                goto out_undo;
        }

        cqe->done = srpt_rdma_read_done;
        for (i = ioctx->n_rw_ctx - 1; i >= 0; i--) {
                struct srpt_rw_ctx *ctx = &ioctx->rw_ctxs[i];

                first_wr = rdma_rw_ctx_wrs(&ctx->rw, ch->qp, ch->sport->port,
                                cqe, first_wr);
                cqe = NULL;
        }
        
        ret = ib_post_send(ch->qp, first_wr, &bad_wr);
        if (ret) {
                pr_err("%s: ib_post_send() returned %d for %d (avail: %d)\n",
                         __func__, ret, ioctx->n_rdma,
                         atomic_read(&ch->sq_wr_avail));
                goto out_undo;
        }

        return 0;
out_undo:
        atomic_add(ioctx->n_rdma, &ch->sq_wr_avail);
        return ret;
}

static u8 tcm_to_srp_tsk_mgmt_status(const int tcm_mgmt_status)
{
        switch (tcm_mgmt_status) {
        case TMR_FUNCTION_COMPLETE:
                return SRP_TSK_MGMT_SUCCESS;
        case TMR_FUNCTION_REJECTED:
                return SRP_TSK_MGMT_FUNC_NOT_SUPP;
        }
        return SRP_TSK_MGMT_FAILED;
}

/**
 * srpt_queue_response() - Transmits the response to a SCSI command.
 *
 * Callback function called by the TCM core. Must not block since it can be
 * invoked on the context of the IB completion handler.
 */
static void srpt_queue_response(struct se_cmd *cmd)
{
        struct srpt_send_ioctx *ioctx =
                container_of(cmd, struct srpt_send_ioctx, cmd);
        struct srpt_rdma_ch *ch = ioctx->ch;
        struct srpt_device *sdev = ch->sport->sdev;
        struct ib_send_wr send_wr, *first_wr = &send_wr, *bad_wr;
        struct ib_sge sge;
        enum srpt_command_state state;
        unsigned long flags;
        int resp_len, ret, i;
        u8 srp_tm_status;

        BUG_ON(!ch);

        spin_lock_irqsave(&ioctx->spinlock, flags);
        state = ioctx->state;
        switch (state) {
        case SRPT_STATE_NEW:
        case SRPT_STATE_DATA_IN:
                ioctx->state = SRPT_STATE_CMD_RSP_SENT;
                break;
        case SRPT_STATE_MGMT:
                ioctx->state = SRPT_STATE_MGMT_RSP_SENT;
                break;
        default:
                WARN(true, "ch %p; cmd %d: unexpected command state %d\n",
                        ch, ioctx->ioctx.index, ioctx->state);
                break;
        }
        spin_unlock_irqrestore(&ioctx->spinlock, flags);

        if (unlikely(transport_check_aborted_status(&ioctx->cmd, false)
                     || WARN_ON_ONCE(state == SRPT_STATE_CMD_RSP_SENT))) {
                atomic_inc(&ch->req_lim_delta);
                srpt_abort_cmd(ioctx);
                return;
        }

        /* For read commands, transfer the data to the initiator. */
        if (ioctx->cmd.data_direction == DMA_FROM_DEVICE &&
            ioctx->cmd.data_length &&
            !ioctx->queue_status_only) {
                for (i = ioctx->n_rw_ctx - 1; i >= 0; i--) {
                        struct srpt_rw_ctx *ctx = &ioctx->rw_ctxs[i];

                        first_wr = rdma_rw_ctx_wrs(&ctx->rw, ch->qp,
                                        ch->sport->port, NULL, first_wr);
                }
        }

        if (state != SRPT_STATE_MGMT)
                resp_len = srpt_build_cmd_rsp(ch, ioctx, ioctx->cmd.tag,
                                              cmd->scsi_status);
        else {
                srp_tm_status
                        = tcm_to_srp_tsk_mgmt_status(cmd->se_tmr_req->response);
                resp_len = srpt_build_tskmgmt_rsp(ch, ioctx, srp_tm_status,
                                                 ioctx->cmd.tag);
        }

        atomic_inc(&ch->req_lim);

        if (unlikely(atomic_sub_return(1 + ioctx->n_rdma,
                        &ch->sq_wr_avail) < 0)) {
                pr_warn("%s: IB send queue full (needed %d)\n",
                                __func__, ioctx->n_rdma);
                ret = -ENOMEM;
                goto out;
        }

        ib_dma_sync_single_for_device(sdev->device, ioctx->ioctx.dma, resp_len,
                                      DMA_TO_DEVICE);

        sge.addr = ioctx->ioctx.dma;
        sge.length = resp_len;
        sge.lkey = sdev->pd->local_dma_lkey;

        ioctx->ioctx.cqe.done = srpt_send_done;
        send_wr.next = NULL;
        send_wr.wr_cqe = &ioctx->ioctx.cqe;
        send_wr.sg_list = &sge;
        send_wr.num_sge = 1;
        send_wr.opcode = IB_WR_SEND;
        send_wr.send_flags = IB_SEND_SIGNALED;

        ret = ib_post_send(ch->qp, first_wr, &bad_wr);
        if (ret < 0) {
                pr_err("%s: sending cmd response failed for tag %llu (%d)\n",
                        __func__, ioctx->cmd.tag, ret);
                goto out;
        }

        return;

out:
        atomic_add(1 + ioctx->n_rdma, &ch->sq_wr_avail);
        atomic_dec(&ch->req_lim);
        srpt_set_cmd_state(ioctx, SRPT_STATE_DONE);
        target_put_sess_cmd(&ioctx->cmd);
}

static int srpt_queue_data_in(struct se_cmd *cmd)
{
        srpt_queue_response(cmd);
        return 0;
}

static void srpt_queue_tm_rsp(struct se_cmd *cmd)
{
        srpt_queue_response(cmd);
}

static void srpt_aborted_task(struct se_cmd *cmd)
{
}

static int srpt_queue_status(struct se_cmd *cmd)
{
        struct srpt_send_ioctx *ioctx;

        ioctx = container_of(cmd, struct srpt_send_ioctx, cmd);
        BUG_ON(ioctx->sense_data != cmd->sense_buffer);
        if (cmd->se_cmd_flags &
            (SCF_TRANSPORT_TASK_SENSE | SCF_EMULATED_TASK_SENSE))
                WARN_ON(cmd->scsi_status != SAM_STAT_CHECK_CONDITION);
        ioctx->queue_status_only = true;
        srpt_queue_response(cmd);
        return 0;
}

static void srpt_refresh_port_work(struct work_struct *work)
{
        struct srpt_port *sport = container_of(work, struct srpt_port, work);

        srpt_refresh_port(sport);
}

/**
 * srpt_release_sdev() - Free the channel resources associated with a target.
 */
static int srpt_release_sdev(struct srpt_device *sdev)
{
        int i, res;

        WARN_ON_ONCE(irqs_disabled());

        BUG_ON(!sdev);

        mutex_lock(&sdev->mutex);
        for (i = 0; i < ARRAY_SIZE(sdev->port); i++)
                sdev->port[i].enabled = false;
        __srpt_close_all_ch(sdev);
        mutex_unlock(&sdev->mutex);

        res = wait_event_interruptible(sdev->ch_releaseQ,
                                       list_empty_careful(&sdev->rch_list));
        if (res)
                pr_err("%s: interrupted.\n", __func__);

        return 0;
}

static struct srpt_port *__srpt_lookup_port(const char *name)
{
        struct ib_device *dev;
        struct srpt_device *sdev;
        struct srpt_port *sport;
        int i;

        list_for_each_entry(sdev, &srpt_dev_list, list) {
                dev = sdev->device;
                if (!dev)
                        continue;

                for (i = 0; i < dev->phys_port_cnt; i++) {
                        sport = &sdev->port[i];

                        if (!strcmp(sport->port_guid, name))
                                return sport;
                }
        }

        return NULL;
}

static struct srpt_port *srpt_lookup_port(const char *name)
{
        struct srpt_port *sport;

        spin_lock(&srpt_dev_lock);
        sport = __srpt_lookup_port(name);
        spin_unlock(&srpt_dev_lock);

        return sport;
}

/**
 * srpt_add_one() - Infiniband device addition callback function.
 */
static void srpt_add_one(struct ib_device *device)
{
        struct srpt_device *sdev;
        struct srpt_port *sport;
        struct ib_srq_init_attr srq_attr;
        int i;

        pr_debug("device = %p, device->dma_ops = %p\n", device,
                 device->dma_ops);

        sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
        if (!sdev)
                goto err;

        sdev->device = device;
        INIT_LIST_HEAD(&sdev->rch_list);
        init_waitqueue_head(&sdev->ch_releaseQ);
        mutex_init(&sdev->mutex);

        sdev->pd = ib_alloc_pd(device, 0);
        if (IS_ERR(sdev->pd))
                goto free_dev;

        sdev->srq_size = min(srpt_srq_size, sdev->device->attrs.max_srq_wr);

        srq_attr.event_handler = srpt_srq_event;
        srq_attr.srq_context = (void *)sdev;
        srq_attr.attr.max_wr = sdev->srq_size;
        srq_attr.attr.max_sge = 1;
        srq_attr.attr.srq_limit = 0;
        srq_attr.srq_type = IB_SRQT_BASIC;

        sdev->srq = ib_create_srq(sdev->pd, &srq_attr);
        if (IS_ERR(sdev->srq))
                goto err_pd;

        pr_debug("%s: create SRQ #wr= %d max_allow=%d dev= %s\n",
                 __func__, sdev->srq_size, sdev->device->attrs.max_srq_wr,
                 device->name);

        if (!srpt_service_guid)
                srpt_service_guid = be64_to_cpu(device->node_guid);

        sdev->cm_id = ib_create_cm_id(device, srpt_cm_handler, sdev);
        if (IS_ERR(sdev->cm_id))
                goto err_srq;

        /* print out target login information */
        pr_debug("Target login info: id_ext=%016llx,ioc_guid=%016llx,"
                 "pkey=ffff,service_id=%016llx\n", srpt_service_guid,
                 srpt_service_guid, srpt_service_guid);

        /*
         * We do not have a consistent service_id (ie. also id_ext of target_id)
         * to identify this target. We currently use the guid of the first HCA
         * in the system as service_id; therefore, the target_id will change
         * if this HCA is gone bad and replaced by different HCA
         */
        if (ib_cm_listen(sdev->cm_id, cpu_to_be64(srpt_service_guid), 0))
                goto err_cm;

        INIT_IB_EVENT_HANDLER(&sdev->event_handler, sdev->device,
                              srpt_event_handler);
        if (ib_register_event_handler(&sdev->event_handler))
                goto err_cm;

        sdev->ioctx_ring = (struct srpt_recv_ioctx **)
                srpt_alloc_ioctx_ring(sdev, sdev->srq_size,
                                      sizeof(*sdev->ioctx_ring[0]),
                                      srp_max_req_size, DMA_FROM_DEVICE);
        if (!sdev->ioctx_ring)
                goto err_event;

        for (i = 0; i < sdev->srq_size; ++i)
                srpt_post_recv(sdev, sdev->ioctx_ring[i]);

        WARN_ON(sdev->device->phys_port_cnt > ARRAY_SIZE(sdev->port));

        for (i = 1; i <= sdev->device->phys_port_cnt; i++) {
                sport = &sdev->port[i - 1];
                sport->sdev = sdev;
                sport->port = i;
                sport->port_attrib.srp_max_rdma_size = DEFAULT_MAX_RDMA_SIZE;
                sport->port_attrib.srp_max_rsp_size = DEFAULT_MAX_RSP_SIZE;
                sport->port_attrib.srp_sq_size = DEF_SRPT_SQ_SIZE;
                INIT_WORK(&sport->work, srpt_refresh_port_work);

                if (srpt_refresh_port(sport)) {
                        pr_err("MAD registration failed for %s-%d.\n",
                               sdev->device->name, i);
                        goto err_ring;
                }
        }

        spin_lock(&srpt_dev_lock);
        list_add_tail(&sdev->list, &srpt_dev_list);
        spin_unlock(&srpt_dev_lock);

out:
        ib_set_client_data(device, &srpt_client, sdev);
        pr_debug("added %s.\n", device->name);
        return;

err_ring:
        srpt_free_ioctx_ring((struct srpt_ioctx **)sdev->ioctx_ring, sdev,
                             sdev->srq_size, srp_max_req_size,
                             DMA_FROM_DEVICE);
err_event:
        ib_unregister_event_handler(&sdev->event_handler);
err_cm:
        ib_destroy_cm_id(sdev->cm_id);
err_srq:
        ib_destroy_srq(sdev->srq);
err_pd:
        ib_dealloc_pd(sdev->pd);
free_dev:
        kfree(sdev);
err:
        sdev = NULL;
        pr_info("%s(%s) failed.\n", __func__, device->name);
        goto out;
}

/**
 * srpt_remove_one() - InfiniBand device removal callback function.
 */
static void srpt_remove_one(struct ib_device *device, void *client_data)
{
        struct srpt_device *sdev = client_data;
        int i;

        if (!sdev) {
                pr_info("%s(%s): nothing to do.\n", __func__, device->name);
                return;
        }

        srpt_unregister_mad_agent(sdev);

        ib_unregister_event_handler(&sdev->event_handler);

        /* Cancel any work queued by the just unregistered IB event handler. */
        for (i = 0; i < sdev->device->phys_port_cnt; i++)
                cancel_work_sync(&sdev->port[i].work);

        ib_destroy_cm_id(sdev->cm_id);

        /*
         * Unregistering a target must happen after destroying sdev->cm_id
         * such that no new SRP_LOGIN_REQ information units can arrive while
         * destroying the target.
         */
        spin_lock(&srpt_dev_lock);
        list_del(&sdev->list);
        spin_unlock(&srpt_dev_lock);
        srpt_release_sdev(sdev);

        ib_destroy_srq(sdev->srq);
        ib_dealloc_pd(sdev->pd);

        srpt_free_ioctx_ring((struct srpt_ioctx **)sdev->ioctx_ring, sdev,
                             sdev->srq_size, srp_max_req_size, DMA_FROM_DEVICE);
        sdev->ioctx_ring = NULL;
        kfree(sdev);
}

static struct ib_client srpt_client = {
        .name = DRV_NAME,
        .add = srpt_add_one,
        .remove = srpt_remove_one
};

static int srpt_check_true(struct se_portal_group *se_tpg)
{
        return 1;
}

static int srpt_check_false(struct se_portal_group *se_tpg)
{
        return 0;
}

static char *srpt_get_fabric_name(void)
{
        return "srpt";
}

static char *srpt_get_fabric_wwn(struct se_portal_group *tpg)
{
        struct srpt_port *sport = container_of(tpg, struct srpt_port, port_tpg_1);

        return sport->port_guid;
}

static u16 srpt_get_tag(struct se_portal_group *tpg)
{
        return 1;
}

static u32 srpt_tpg_get_inst_index(struct se_portal_group *se_tpg)
{
        return 1;
}

static void srpt_release_cmd(struct se_cmd *se_cmd)
{
        struct srpt_send_ioctx *ioctx = container_of(se_cmd,
                                struct srpt_send_ioctx, cmd);
        struct srpt_rdma_ch *ch = ioctx->ch;
        unsigned long flags;

        WARN_ON(ioctx->state != SRPT_STATE_DONE);

        if (ioctx->n_rw_ctx) {
                srpt_free_rw_ctxs(ch, ioctx);
                ioctx->n_rw_ctx = 0;
        }

        spin_lock_irqsave(&ch->spinlock, flags);
        list_add(&ioctx->free_list, &ch->free_list);
        spin_unlock_irqrestore(&ch->spinlock, flags);
}

/**
 * srpt_close_session() - Forcibly close a session.
 *
 * Callback function invoked by the TCM core to clean up sessions associated
 * with a node ACL when the user invokes
 * rmdir /sys/kernel/config/target/$driver/$port/$tpg/acls/$i_port_id
 */
static void srpt_close_session(struct se_session *se_sess)
{
        DECLARE_COMPLETION_ONSTACK(release_done);
        struct srpt_rdma_ch *ch = se_sess->fabric_sess_ptr;
        struct srpt_device *sdev = ch->sport->sdev;
        bool wait;

        pr_debug("ch %s-%d state %d\n", ch->sess_name, ch->qp->qp_num,
                 ch->state);

        mutex_lock(&sdev->mutex);
        BUG_ON(ch->release_done);
        ch->release_done = &release_done;
        wait = !list_empty(&ch->list);
        srpt_disconnect_ch(ch);
        mutex_unlock(&sdev->mutex);

        if (!wait)
                return;

        while (wait_for_completion_timeout(&release_done, 180 * HZ) == 0)
                pr_info("%s(%s-%d state %d): still waiting ...\n", __func__,
                        ch->sess_name, ch->qp->qp_num, ch->state);
}

/**
 * srpt_sess_get_index() - Return the value of scsiAttIntrPortIndex (SCSI-MIB).
 *
 * A quote from RFC 4455 (SCSI-MIB) about this MIB object:
 * This object represents an arbitrary integer used to uniquely identify a
 * particular attached remote initiator port to a particular SCSI target port
 * within a particular SCSI target device within a particular SCSI instance.
 */
static u32 srpt_sess_get_index(struct se_session *se_sess)
{
        return 0;
}

static void srpt_set_default_node_attrs(struct se_node_acl *nacl)
{
}

/* Note: only used from inside debug printk's by the TCM core. */
static int srpt_get_tcm_cmd_state(struct se_cmd *se_cmd)
{
        struct srpt_send_ioctx *ioctx;

        ioctx = container_of(se_cmd, struct srpt_send_ioctx, cmd);
        return srpt_get_cmd_state(ioctx);
}

/**
 * srpt_parse_i_port_id() - Parse an initiator port ID.
 * @name: ASCII representation of a 128-bit initiator port ID.
 * @i_port_id: Binary 128-bit port ID.
 */
static int srpt_parse_i_port_id(u8 i_port_id[16], const char *name)
{
        const char *p;
        unsigned len, count, leading_zero_bytes;
        int ret, rc;

        p = name;
        if (strncasecmp(p, "0x", 2) == 0)
                p += 2;
        ret = -EINVAL;
        len = strlen(p);
        if (len % 2)
                goto out;
        count = min(len / 2, 16U);
        leading_zero_bytes = 16 - count;
        memset(i_port_id, 0, leading_zero_bytes);
        rc = hex2bin(i_port_id + leading_zero_bytes, p, count);
        if (rc < 0)
                pr_debug("hex2bin failed for srpt_parse_i_port_id: %d\n", rc);
        ret = 0;
out:
        return ret;
}

/*
 * configfs callback function invoked for
 * mkdir /sys/kernel/config/target/$driver/$port/$tpg/acls/$i_port_id
 */
static int srpt_init_nodeacl(struct se_node_acl *se_nacl, const char *name)
{
        u8 i_port_id[16];

        if (srpt_parse_i_port_id(i_port_id, name) < 0) {
                pr_err("invalid initiator port ID %s\n", name);
                return -EINVAL;
        }
        return 0;
}

static ssize_t srpt_tpg_attrib_srp_max_rdma_size_show(struct config_item *item,
                char *page)
{
        struct se_portal_group *se_tpg = attrib_to_tpg(item);
        struct srpt_port *sport = container_of(se_tpg, struct srpt_port, port_tpg_1);

        return sprintf(page, "%u\n", sport->port_attrib.srp_max_rdma_size);
}

static ssize_t srpt_tpg_attrib_srp_max_rdma_size_store(struct config_item *item,
                const char *page, size_t count)
{
        struct se_portal_group *se_tpg = attrib_to_tpg(item);
        struct srpt_port *sport = container_of(se_tpg, struct srpt_port, port_tpg_1);
        unsigned long val;
        int ret;

        ret = kstrtoul(page, 0, &val);
        if (ret < 0) {
                pr_err("kstrtoul() failed with ret: %d\n", ret);
                return -EINVAL;
        }
        if (val > MAX_SRPT_RDMA_SIZE) {
                pr_err("val: %lu exceeds MAX_SRPT_RDMA_SIZE: %d\n", val,
                        MAX_SRPT_RDMA_SIZE);
                return -EINVAL;
        }
        if (val < DEFAULT_MAX_RDMA_SIZE) {
                pr_err("val: %lu smaller than DEFAULT_MAX_RDMA_SIZE: %d\n",
                        val, DEFAULT_MAX_RDMA_SIZE);
                return -EINVAL;
        }
        sport->port_attrib.srp_max_rdma_size = val;

        return count;
}

static ssize_t srpt_tpg_attrib_srp_max_rsp_size_show(struct config_item *item,
                char *page)
{
        struct se_portal_group *se_tpg = attrib_to_tpg(item);
        struct srpt_port *sport = container_of(se_tpg, struct srpt_port, port_tpg_1);

        return sprintf(page, "%u\n", sport->port_attrib.srp_max_rsp_size);
}

static ssize_t srpt_tpg_attrib_srp_max_rsp_size_store(struct config_item *item,
                const char *page, size_t count)
{
        struct se_portal_group *se_tpg = attrib_to_tpg(item);
        struct srpt_port *sport = container_of(se_tpg, struct srpt_port, port_tpg_1);
        unsigned long val;
        int ret;

        ret = kstrtoul(page, 0, &val);
        if (ret < 0) {
                pr_err("kstrtoul() failed with ret: %d\n", ret);
                return -EINVAL;
        }
        if (val > MAX_SRPT_RSP_SIZE) {
                pr_err("val: %lu exceeds MAX_SRPT_RSP_SIZE: %d\n", val,
                        MAX_SRPT_RSP_SIZE);
                return -EINVAL;
        }
        if (val < MIN_MAX_RSP_SIZE) {
                pr_err("val: %lu smaller than MIN_MAX_RSP_SIZE: %d\n", val,
                        MIN_MAX_RSP_SIZE);
                return -EINVAL;
        }
        sport->port_attrib.srp_max_rsp_size = val;

        return count;
}

static ssize_t srpt_tpg_attrib_srp_sq_size_show(struct config_item *item,
                char *page)
{
        struct se_portal_group *se_tpg = attrib_to_tpg(item);
        struct srpt_port *sport = container_of(se_tpg, struct srpt_port, port_tpg_1);

        return sprintf(page, "%u\n", sport->port_attrib.srp_sq_size);
}

static ssize_t srpt_tpg_attrib_srp_sq_size_store(struct config_item *item,
                const char *page, size_t count)
{
        struct se_portal_group *se_tpg = attrib_to_tpg(item);
        struct srpt_port *sport = container_of(se_tpg, struct srpt_port, port_tpg_1);
        unsigned long val;
        int ret;

        ret = kstrtoul(page, 0, &val);
        if (ret < 0) {
                pr_err("kstrtoul() failed with ret: %d\n", ret);
                return -EINVAL;
        }
        if (val > MAX_SRPT_SRQ_SIZE) {
                pr_err("val: %lu exceeds MAX_SRPT_SRQ_SIZE: %d\n", val,
                        MAX_SRPT_SRQ_SIZE);
                return -EINVAL;
        }
        if (val < MIN_SRPT_SRQ_SIZE) {
                pr_err("val: %lu smaller than MIN_SRPT_SRQ_SIZE: %d\n", val,
                        MIN_SRPT_SRQ_SIZE);
                return -EINVAL;
        }
        sport->port_attrib.srp_sq_size = val;

        return count;
}

CONFIGFS_ATTR(srpt_tpg_attrib_,  srp_max_rdma_size);
CONFIGFS_ATTR(srpt_tpg_attrib_,  srp_max_rsp_size);
CONFIGFS_ATTR(srpt_tpg_attrib_,  srp_sq_size);

static struct configfs_attribute *srpt_tpg_attrib_attrs[] = {
        &srpt_tpg_attrib_attr_srp_max_rdma_size,
        &srpt_tpg_attrib_attr_srp_max_rsp_size,
        &srpt_tpg_attrib_attr_srp_sq_size,
        NULL,
};

static ssize_t srpt_tpg_enable_show(struct config_item *item, char *page)
{
        struct se_portal_group *se_tpg = to_tpg(item);
        struct srpt_port *sport = container_of(se_tpg, struct srpt_port, port_tpg_1);

        return snprintf(page, PAGE_SIZE, "%d\n", (sport->enabled) ? 1: 0);
}

static ssize_t srpt_tpg_enable_store(struct config_item *item,
                const char *page, size_t count)
{
        struct se_portal_group *se_tpg = to_tpg(item);
        struct srpt_port *sport = container_of(se_tpg, struct srpt_port, port_tpg_1);
        struct srpt_device *sdev = sport->sdev;
        struct srpt_rdma_ch *ch;
        unsigned long tmp;
        int ret;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract srpt_tpg_store_enable\n");
                return -EINVAL;
        }

        if ((tmp != 0) && (tmp != 1)) {
                pr_err("Illegal value for srpt_tpg_store_enable: %lu\n", tmp);
                return -EINVAL;
        }
        if (sport->enabled == tmp)
                goto out;
        sport->enabled = tmp;
        if (sport->enabled)
                goto out;

        mutex_lock(&sdev->mutex);
        list_for_each_entry(ch, &sdev->rch_list, list) {
                if (ch->sport == sport) {
                        pr_debug("%s: ch %p %s-%d\n", __func__, ch,
                                 ch->sess_name, ch->qp->qp_num);
                        srpt_disconnect_ch(ch);
                        srpt_close_ch(ch);
                }
        }
        mutex_unlock(&sdev->mutex);

out:
        return count;
}

CONFIGFS_ATTR(srpt_tpg_, enable);

static struct configfs_attribute *srpt_tpg_attrs[] = {
        &srpt_tpg_attr_enable,
        NULL,
};

/**
 * configfs callback invoked for
 * mkdir /sys/kernel/config/target/$driver/$port/$tpg
 */
static struct se_portal_group *srpt_make_tpg(struct se_wwn *wwn,
                                             struct config_group *group,
                                             const char *name)
{
        struct srpt_port *sport = container_of(wwn, struct srpt_port, port_wwn);
        int res;

        /* Initialize sport->port_wwn and sport->port_tpg_1 */
        res = core_tpg_register(&sport->port_wwn, &sport->port_tpg_1, SCSI_PROTOCOL_SRP);
        if (res)
                return ERR_PTR(res);

        return &sport->port_tpg_1;
}

/**
 * configfs callback invoked for
 * rmdir /sys/kernel/config/target/$driver/$port/$tpg
 */
static void srpt_drop_tpg(struct se_portal_group *tpg)
{
        struct srpt_port *sport = container_of(tpg,
                                struct srpt_port, port_tpg_1);

        sport->enabled = false;
        core_tpg_deregister(&sport->port_tpg_1);
}

/**
 * configfs callback invoked for
 * mkdir /sys/kernel/config/target/$driver/$port