of: MSI: Simplify irqdomain lookup

[linux/fpc-iii.git] / drivers / infiniband / ulp / iser / iser_verbs.c

/*
 * Copyright (c) 2004, 2005, 2006 Voltaire, Inc. All rights reserved.
 * Copyright (c) 2005, 2006 Cisco Systems.  All rights reserved.
 * Copyright (c) 2013-2014 Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/delay.h>

#include "iscsi_iser.h"

#define ISCSI_ISER_MAX_CONN     8
#define ISER_MAX_RX_LEN         (ISER_QP_MAX_RECV_DTOS * ISCSI_ISER_MAX_CONN)
#define ISER_MAX_TX_LEN         (ISER_QP_MAX_REQ_DTOS  * ISCSI_ISER_MAX_CONN)
#define ISER_MAX_CQ_LEN         (ISER_MAX_RX_LEN + ISER_MAX_TX_LEN + \
                                 ISCSI_ISER_MAX_CONN)

static int iser_cq_poll_limit = 512;

static void iser_cq_tasklet_fn(unsigned long data);
static void iser_cq_callback(struct ib_cq *cq, void *cq_context);

static void iser_cq_event_callback(struct ib_event *cause, void *context)
{
        iser_err("cq event %s (%d)\n",
                 ib_event_msg(cause->event), cause->event);
}

static void iser_qp_event_callback(struct ib_event *cause, void *context)
{
        iser_err("qp event %s (%d)\n",
                 ib_event_msg(cause->event), cause->event);
}

static void iser_event_handler(struct ib_event_handler *handler,
                                struct ib_event *event)
{
        iser_err("async event %s (%d) on device %s port %d\n",
                 ib_event_msg(event->event), event->event,
                 event->device->name, event->element.port_num);
}

/**
 * iser_create_device_ib_res - creates Protection Domain (PD), Completion
 * Queue (CQ), DMA Memory Region (DMA MR) with the device associated with
 * the adapator.
 *
 * returns 0 on success, -1 on failure
 */
static int iser_create_device_ib_res(struct iser_device *device)
{
        struct ib_device_attr *dev_attr = &device->dev_attr;
        int ret, i, max_cqe;

        ret = ib_query_device(device->ib_device, dev_attr);
        if (ret) {
                pr_warn("Query device failed for %s\n", device->ib_device->name);
                return ret;
        }

        ret = iser_assign_reg_ops(device);
        if (ret)
                return ret;

        device->comps_used = min_t(int, num_online_cpus(),
                                 device->ib_device->num_comp_vectors);

        device->comps = kcalloc(device->comps_used, sizeof(*device->comps),
                                GFP_KERNEL);
        if (!device->comps)
                goto comps_err;

        max_cqe = min(ISER_MAX_CQ_LEN, dev_attr->max_cqe);

        iser_info("using %d CQs, device %s supports %d vectors max_cqe %d\n",
                  device->comps_used, device->ib_device->name,
                  device->ib_device->num_comp_vectors, max_cqe);

        device->pd = ib_alloc_pd(device->ib_device);
        if (IS_ERR(device->pd))
                goto pd_err;

        for (i = 0; i < device->comps_used; i++) {
                struct ib_cq_init_attr cq_attr = {};
                struct iser_comp *comp = &device->comps[i];

                comp->device = device;
                cq_attr.cqe = max_cqe;
                cq_attr.comp_vector = i;
                comp->cq = ib_create_cq(device->ib_device,
                                        iser_cq_callback,
                                        iser_cq_event_callback,
                                        (void *)comp,
                                        &cq_attr);
                if (IS_ERR(comp->cq)) {
                        comp->cq = NULL;
                        goto cq_err;
                }

                if (ib_req_notify_cq(comp->cq, IB_CQ_NEXT_COMP))
                        goto cq_err;

                tasklet_init(&comp->tasklet, iser_cq_tasklet_fn,
                             (unsigned long)comp);
        }

        if (!iser_always_reg) {
                int access = IB_ACCESS_LOCAL_WRITE |
                             IB_ACCESS_REMOTE_WRITE |
                             IB_ACCESS_REMOTE_READ;

                device->mr = ib_get_dma_mr(device->pd, access);
                if (IS_ERR(device->mr))
                        goto dma_mr_err;
        }

        INIT_IB_EVENT_HANDLER(&device->event_handler, device->ib_device,
                                iser_event_handler);
        if (ib_register_event_handler(&device->event_handler))
                goto handler_err;

        return 0;

handler_err:
        if (device->mr)
                ib_dereg_mr(device->mr);
dma_mr_err:
        for (i = 0; i < device->comps_used; i++)
                tasklet_kill(&device->comps[i].tasklet);
cq_err:
        for (i = 0; i < device->comps_used; i++) {
                struct iser_comp *comp = &device->comps[i];

                if (comp->cq)
                        ib_destroy_cq(comp->cq);
        }
        ib_dealloc_pd(device->pd);
pd_err:
        kfree(device->comps);
comps_err:
        iser_err("failed to allocate an IB resource\n");
        return -1;
}

/**
 * iser_free_device_ib_res - destroy/dealloc/dereg the DMA MR,
 * CQ and PD created with the device associated with the adapator.
 */
static void iser_free_device_ib_res(struct iser_device *device)
{
        int i;

        for (i = 0; i < device->comps_used; i++) {
                struct iser_comp *comp = &device->comps[i];

                tasklet_kill(&comp->tasklet);
                ib_destroy_cq(comp->cq);
                comp->cq = NULL;
        }

        (void)ib_unregister_event_handler(&device->event_handler);
        if (device->mr)
                (void)ib_dereg_mr(device->mr);
        ib_dealloc_pd(device->pd);

        kfree(device->comps);
        device->comps = NULL;

        device->mr = NULL;
        device->pd = NULL;
}

/**
 * iser_alloc_fmr_pool - Creates FMR pool and page_vector
 *
 * returns 0 on success, or errno code on failure
 */
int iser_alloc_fmr_pool(struct ib_conn *ib_conn,
                        unsigned cmds_max,
                        unsigned int size)
{
        struct iser_device *device = ib_conn->device;
        struct iser_fr_pool *fr_pool = &ib_conn->fr_pool;
        struct iser_page_vec *page_vec;
        struct iser_fr_desc *desc;
        struct ib_fmr_pool *fmr_pool;
        struct ib_fmr_pool_param params;
        int ret;

        INIT_LIST_HEAD(&fr_pool->list);
        spin_lock_init(&fr_pool->lock);

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

        page_vec = kmalloc(sizeof(*page_vec) + (sizeof(u64) * size),
                           GFP_KERNEL);
        if (!page_vec) {
                ret = -ENOMEM;
                goto err_frpl;
        }

        page_vec->pages = (u64 *)(page_vec + 1);

        params.page_shift        = SHIFT_4K;
        params.max_pages_per_fmr = size;
        /* make the pool size twice the max number of SCSI commands *
         * the ML is expected to queue, watermark for unmap at 50%  */
        params.pool_size         = cmds_max * 2;
        params.dirty_watermark   = cmds_max;
        params.cache             = 0;
        params.flush_function    = NULL;
        params.access            = (IB_ACCESS_LOCAL_WRITE  |
                                    IB_ACCESS_REMOTE_WRITE |
                                    IB_ACCESS_REMOTE_READ);

        fmr_pool = ib_create_fmr_pool(device->pd, &params);
        if (IS_ERR(fmr_pool)) {
                ret = PTR_ERR(fmr_pool);
                iser_err("FMR allocation failed, err %d\n", ret);
                goto err_fmr;
        }

        desc->rsc.page_vec = page_vec;
        desc->rsc.fmr_pool = fmr_pool;
        list_add(&desc->list, &fr_pool->list);

        return 0;

err_fmr:
        kfree(page_vec);
err_frpl:
        kfree(desc);

        return ret;
}

/**
 * iser_free_fmr_pool - releases the FMR pool and page vec
 */
void iser_free_fmr_pool(struct ib_conn *ib_conn)
{
        struct iser_fr_pool *fr_pool = &ib_conn->fr_pool;
        struct iser_fr_desc *desc;

        desc = list_first_entry(&fr_pool->list,
                                struct iser_fr_desc, list);
        list_del(&desc->list);

        iser_info("freeing conn %p fmr pool %p\n",
                  ib_conn, desc->rsc.fmr_pool);

        ib_destroy_fmr_pool(desc->rsc.fmr_pool);
        kfree(desc->rsc.page_vec);
        kfree(desc);
}

static int
iser_alloc_reg_res(struct ib_device *ib_device,
                   struct ib_pd *pd,
                   struct iser_reg_resources *res,
                   unsigned int size)
{
        int ret;

        res->mr = ib_alloc_mr(pd, IB_MR_TYPE_MEM_REG, size);
        if (IS_ERR(res->mr)) {
                ret = PTR_ERR(res->mr);
                iser_err("Failed to allocate ib_fast_reg_mr err=%d\n", ret);
                return ret;
        }
        res->mr_valid = 1;

        return 0;
}

static void
iser_free_reg_res(struct iser_reg_resources *rsc)
{
        ib_dereg_mr(rsc->mr);
}

static int
iser_alloc_pi_ctx(struct ib_device *ib_device,
                  struct ib_pd *pd,
                  struct iser_fr_desc *desc,
                  unsigned int size)
{
        struct iser_pi_context *pi_ctx = NULL;
        int ret;

        desc->pi_ctx = kzalloc(sizeof(*desc->pi_ctx), GFP_KERNEL);
        if (!desc->pi_ctx)
                return -ENOMEM;

        pi_ctx = desc->pi_ctx;

        ret = iser_alloc_reg_res(ib_device, pd, &pi_ctx->rsc, size);
        if (ret) {
                iser_err("failed to allocate reg_resources\n");
                goto alloc_reg_res_err;
        }

        pi_ctx->sig_mr = ib_alloc_mr(pd, IB_MR_TYPE_SIGNATURE, 2);
        if (IS_ERR(pi_ctx->sig_mr)) {
                ret = PTR_ERR(pi_ctx->sig_mr);
                goto sig_mr_failure;
        }
        pi_ctx->sig_mr_valid = 1;
        desc->pi_ctx->sig_protected = 0;

        return 0;

sig_mr_failure:
        iser_free_reg_res(&pi_ctx->rsc);
alloc_reg_res_err:
        kfree(desc->pi_ctx);

        return ret;
}

static void
iser_free_pi_ctx(struct iser_pi_context *pi_ctx)
{
        iser_free_reg_res(&pi_ctx->rsc);
        ib_dereg_mr(pi_ctx->sig_mr);
        kfree(pi_ctx);
}

static struct iser_fr_desc *
iser_create_fastreg_desc(struct ib_device *ib_device,
                         struct ib_pd *pd,
                         bool pi_enable,
                         unsigned int size)
{
        struct iser_fr_desc *desc;
        int ret;

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

        ret = iser_alloc_reg_res(ib_device, pd, &desc->rsc, size);
        if (ret)
                goto reg_res_alloc_failure;

        if (pi_enable) {
                ret = iser_alloc_pi_ctx(ib_device, pd, desc, size);
                if (ret)
                        goto pi_ctx_alloc_failure;
        }

        return desc;

pi_ctx_alloc_failure:
        iser_free_reg_res(&desc->rsc);
reg_res_alloc_failure:
        kfree(desc);

        return ERR_PTR(ret);
}

/**
 * iser_alloc_fastreg_pool - Creates pool of fast_reg descriptors
 * for fast registration work requests.
 * returns 0 on success, or errno code on failure
 */
int iser_alloc_fastreg_pool(struct ib_conn *ib_conn,
                            unsigned cmds_max,
                            unsigned int size)
{
        struct iser_device *device = ib_conn->device;
        struct iser_fr_pool *fr_pool = &ib_conn->fr_pool;
        struct iser_fr_desc *desc;
        int i, ret;

        INIT_LIST_HEAD(&fr_pool->list);
        spin_lock_init(&fr_pool->lock);
        fr_pool->size = 0;
        for (i = 0; i < cmds_max; i++) {
                desc = iser_create_fastreg_desc(device->ib_device, device->pd,
                                                ib_conn->pi_support, size);
                if (IS_ERR(desc)) {
                        ret = PTR_ERR(desc);
                        goto err;
                }

                list_add_tail(&desc->list, &fr_pool->list);
                fr_pool->size++;
        }

        return 0;

err:
        iser_free_fastreg_pool(ib_conn);
        return ret;
}

/**
 * iser_free_fastreg_pool - releases the pool of fast_reg descriptors
 */
void iser_free_fastreg_pool(struct ib_conn *ib_conn)
{
        struct iser_fr_pool *fr_pool = &ib_conn->fr_pool;
        struct iser_fr_desc *desc, *tmp;
        int i = 0;

        if (list_empty(&fr_pool->list))
                return;

        iser_info("freeing conn %p fr pool\n", ib_conn);

        list_for_each_entry_safe(desc, tmp, &fr_pool->list, list) {
                list_del(&desc->list);
                iser_free_reg_res(&desc->rsc);
                if (desc->pi_ctx)
                        iser_free_pi_ctx(desc->pi_ctx);
                kfree(desc);
                ++i;
        }

        if (i < fr_pool->size)
                iser_warn("pool still has %d regions registered\n",
                          fr_pool->size - i);
}

/**
 * iser_create_ib_conn_res - Queue-Pair (QP)
 *
 * returns 0 on success, -1 on failure
 */
static int iser_create_ib_conn_res(struct ib_conn *ib_conn)
{
        struct iser_conn *iser_conn = container_of(ib_conn, struct iser_conn,
                                                   ib_conn);
        struct iser_device      *device;
        struct ib_device_attr *dev_attr;
        struct ib_qp_init_attr  init_attr;
        int                     ret = -ENOMEM;
        int index, min_index = 0;

        BUG_ON(ib_conn->device == NULL);

        device = ib_conn->device;
        dev_attr = &device->dev_attr;

        memset(&init_attr, 0, sizeof init_attr);

        mutex_lock(&ig.connlist_mutex);
        /* select the CQ with the minimal number of usages */
        for (index = 0; index < device->comps_used; index++) {
                if (device->comps[index].active_qps <
                    device->comps[min_index].active_qps)
                        min_index = index;
        }
        ib_conn->comp = &device->comps[min_index];
        ib_conn->comp->active_qps++;
        mutex_unlock(&ig.connlist_mutex);
        iser_info("cq index %d used for ib_conn %p\n", min_index, ib_conn);

        init_attr.event_handler = iser_qp_event_callback;
        init_attr.qp_context    = (void *)ib_conn;
        init_attr.send_cq       = ib_conn->comp->cq;
        init_attr.recv_cq       = ib_conn->comp->cq;
        init_attr.cap.max_recv_wr  = ISER_QP_MAX_RECV_DTOS;
        init_attr.cap.max_send_sge = 2;
        init_attr.cap.max_recv_sge = 1;
        init_attr.sq_sig_type   = IB_SIGNAL_REQ_WR;
        init_attr.qp_type       = IB_QPT_RC;
        if (ib_conn->pi_support) {
                init_attr.cap.max_send_wr = ISER_QP_SIG_MAX_REQ_DTOS + 1;
                init_attr.create_flags |= IB_QP_CREATE_SIGNATURE_EN;
                iser_conn->max_cmds =
                        ISER_GET_MAX_XMIT_CMDS(ISER_QP_SIG_MAX_REQ_DTOS);
        } else {
                if (dev_attr->max_qp_wr > ISER_QP_MAX_REQ_DTOS) {
                        init_attr.cap.max_send_wr  = ISER_QP_MAX_REQ_DTOS + 1;
                        iser_conn->max_cmds =
                                ISER_GET_MAX_XMIT_CMDS(ISER_QP_MAX_REQ_DTOS);
                } else {
                        init_attr.cap.max_send_wr = dev_attr->max_qp_wr;
                        iser_conn->max_cmds =
                                ISER_GET_MAX_XMIT_CMDS(dev_attr->max_qp_wr);
                        iser_dbg("device %s supports max_send_wr %d\n",
                                 device->ib_device->name, dev_attr->max_qp_wr);
                }
        }

        ret = rdma_create_qp(ib_conn->cma_id, device->pd, &init_attr);
        if (ret)
                goto out_err;

        ib_conn->qp = ib_conn->cma_id->qp;
        iser_info("setting conn %p cma_id %p qp %p\n",
                  ib_conn, ib_conn->cma_id,
                  ib_conn->cma_id->qp);
        return ret;

out_err:
        mutex_lock(&ig.connlist_mutex);
        ib_conn->comp->active_qps--;
        mutex_unlock(&ig.connlist_mutex);
        iser_err("unable to alloc mem or create resource, err %d\n", ret);

        return ret;
}

/**
 * based on the resolved device node GUID see if there already allocated
 * device for this device. If there's no such, create one.
 */
static
struct iser_device *iser_device_find_by_ib_device(struct rdma_cm_id *cma_id)
{
        struct iser_device *device;

        mutex_lock(&ig.device_list_mutex);

        list_for_each_entry(device, &ig.device_list, ig_list)
                /* find if there's a match using the node GUID */
                if (device->ib_device->node_guid == cma_id->device->node_guid)
                        goto inc_refcnt;

        device = kzalloc(sizeof *device, GFP_KERNEL);
        if (device == NULL)
                goto out;

        /* assign this device to the device */
        device->ib_device = cma_id->device;
        /* init the device and link it into ig device list */
        if (iser_create_device_ib_res(device)) {
                kfree(device);
                device = NULL;
                goto out;
        }
        list_add(&device->ig_list, &ig.device_list);

inc_refcnt:
        device->refcount++;
out:
        mutex_unlock(&ig.device_list_mutex);
        return device;
}

/* if there's no demand for this device, release it */
static void iser_device_try_release(struct iser_device *device)
{
        mutex_lock(&ig.device_list_mutex);
        device->refcount--;
        iser_info("device %p refcount %d\n", device, device->refcount);
        if (!device->refcount) {
                iser_free_device_ib_res(device);
                list_del(&device->ig_list);
                kfree(device);
        }
        mutex_unlock(&ig.device_list_mutex);
}

/**
 * Called with state mutex held
 **/
static int iser_conn_state_comp_exch(struct iser_conn *iser_conn,
                                     enum iser_conn_state comp,
                                     enum iser_conn_state exch)
{
        int ret;

        ret = (iser_conn->state == comp);
        if (ret)
                iser_conn->state = exch;

        return ret;
}

void iser_release_work(struct work_struct *work)
{
        struct iser_conn *iser_conn;

        iser_conn = container_of(work, struct iser_conn, release_work);

        /* Wait for conn_stop to complete */
        wait_for_completion(&iser_conn->stop_completion);
        /* Wait for IB resouces cleanup to complete */
        wait_for_completion(&iser_conn->ib_completion);

        mutex_lock(&iser_conn->state_mutex);
        iser_conn->state = ISER_CONN_DOWN;
        mutex_unlock(&iser_conn->state_mutex);

        iser_conn_release(iser_conn);
}

/**
 * iser_free_ib_conn_res - release IB related resources
 * @iser_conn: iser connection struct
 * @destroy: indicator if we need to try to release the
 *     iser device and memory regoins pool (only iscsi
 *     shutdown and DEVICE_REMOVAL will use this).
 *
 * This routine is called with the iser state mutex held
 * so the cm_id removal is out of here. It is Safe to
 * be invoked multiple times.
 */
static void iser_free_ib_conn_res(struct iser_conn *iser_conn,
                                  bool destroy)
{
        struct ib_conn *ib_conn = &iser_conn->ib_conn;
        struct iser_device *device = ib_conn->device;

        iser_info("freeing conn %p cma_id %p qp %p\n",
                  iser_conn, ib_conn->cma_id, ib_conn->qp);

        if (ib_conn->qp != NULL) {
                ib_conn->comp->active_qps--;
                rdma_destroy_qp(ib_conn->cma_id);
                ib_conn->qp = NULL;
        }

        if (destroy) {
                if (iser_conn->rx_descs)
                        iser_free_rx_descriptors(iser_conn);

                if (device != NULL) {
                        iser_device_try_release(device);
                        ib_conn->device = NULL;
                }
        }
}

/**
 * Frees all conn objects and deallocs conn descriptor
 */
void iser_conn_release(struct iser_conn *iser_conn)
{
        struct ib_conn *ib_conn = &iser_conn->ib_conn;

        mutex_lock(&ig.connlist_mutex);
        list_del(&iser_conn->conn_list);
        mutex_unlock(&ig.connlist_mutex);

        mutex_lock(&iser_conn->state_mutex);
        /* In case we endup here without ep_disconnect being invoked. */
        if (iser_conn->state != ISER_CONN_DOWN) {
                iser_warn("iser conn %p state %d, expected state down.\n",
                          iser_conn, iser_conn->state);
                iscsi_destroy_endpoint(iser_conn->ep);
                iser_conn->state = ISER_CONN_DOWN;
        }
        /*
         * In case we never got to bind stage, we still need to
         * release IB resources (which is safe to call more than once).
         */
        iser_free_ib_conn_res(iser_conn, true);
        mutex_unlock(&iser_conn->state_mutex);

        if (ib_conn->cma_id != NULL) {
                rdma_destroy_id(ib_conn->cma_id);
                ib_conn->cma_id = NULL;
        }

        kfree(iser_conn);
}

/**
 * triggers start of the disconnect procedures and wait for them to be done
 * Called with state mutex held
 */
int iser_conn_terminate(struct iser_conn *iser_conn)
{
        struct ib_conn *ib_conn = &iser_conn->ib_conn;
        struct ib_send_wr *bad_wr;
        int err = 0;

        /* terminate the iser conn only if the conn state is UP */
        if (!iser_conn_state_comp_exch(iser_conn, ISER_CONN_UP,
                                       ISER_CONN_TERMINATING))
                return 0;

        iser_info("iser_conn %p state %d\n", iser_conn, iser_conn->state);

        /* suspend queuing of new iscsi commands */
        if (iser_conn->iscsi_conn)
                iscsi_suspend_queue(iser_conn->iscsi_conn);

        /*
         * In case we didn't already clean up the cma_id (peer initiated
         * a disconnection), we need to Cause the CMA to change the QP
         * state to ERROR.
         */
        if (ib_conn->cma_id) {
                err = rdma_disconnect(ib_conn->cma_id);
                if (err)
                        iser_err("Failed to disconnect, conn: 0x%p err %d\n",
                                 iser_conn, err);

                /* post an indication that all flush errors were consumed */
                err = ib_post_send(ib_conn->qp, &ib_conn->beacon, &bad_wr);
                if (err) {
                        iser_err("conn %p failed to post beacon", ib_conn);
                        return 1;
                }

                wait_for_completion(&ib_conn->flush_comp);
        }

        return 1;
}

/**
 * Called with state mutex held
 **/
static void iser_connect_error(struct rdma_cm_id *cma_id)
{
        struct iser_conn *iser_conn;

        iser_conn = (struct iser_conn *)cma_id->context;
        iser_conn->state = ISER_CONN_TERMINATING;
}

static void
iser_calc_scsi_params(struct iser_conn *iser_conn,
                      unsigned int max_sectors)
{
        struct iser_device *device = iser_conn->ib_conn.device;
        unsigned short sg_tablesize, sup_sg_tablesize;

        sg_tablesize = DIV_ROUND_UP(max_sectors * 512, SIZE_4K);
        sup_sg_tablesize = min_t(unsigned, ISCSI_ISER_MAX_SG_TABLESIZE,
                                 device->dev_attr.max_fast_reg_page_list_len);

        if (sg_tablesize > sup_sg_tablesize) {
                sg_tablesize = sup_sg_tablesize;
                iser_conn->scsi_max_sectors = sg_tablesize * SIZE_4K / 512;
        } else {
                iser_conn->scsi_max_sectors = max_sectors;
        }

        iser_conn->scsi_sg_tablesize = sg_tablesize;

        iser_dbg("iser_conn %p, sg_tablesize %u, max_sectors %u\n",
                 iser_conn, iser_conn->scsi_sg_tablesize,
                 iser_conn->scsi_max_sectors);
}

/**
 * Called with state mutex held
 **/
static void iser_addr_handler(struct rdma_cm_id *cma_id)
{
        struct iser_device *device;
        struct iser_conn   *iser_conn;
        struct ib_conn   *ib_conn;
        int    ret;

        iser_conn = (struct iser_conn *)cma_id->context;
        if (iser_conn->state != ISER_CONN_PENDING)
                /* bailout */
                return;

        ib_conn = &iser_conn->ib_conn;
        device = iser_device_find_by_ib_device(cma_id);
        if (!device) {
                iser_err("device lookup/creation failed\n");
                iser_connect_error(cma_id);
                return;
        }

        ib_conn->device = device;

        /* connection T10-PI support */
        if (iser_pi_enable) {
                if (!(device->dev_attr.device_cap_flags &
                      IB_DEVICE_SIGNATURE_HANDOVER)) {
                        iser_warn("T10-PI requested but not supported on %s, "
                                  "continue without T10-PI\n",
                                  ib_conn->device->ib_device->name);
                        ib_conn->pi_support = false;
                } else {
                        ib_conn->pi_support = true;
                }
        }

        iser_calc_scsi_params(iser_conn, iser_max_sectors);

        ret = rdma_resolve_route(cma_id, 1000);
        if (ret) {
                iser_err("resolve route failed: %d\n", ret);
                iser_connect_error(cma_id);
                return;
        }
}

/**
 * Called with state mutex held
 **/
static void iser_route_handler(struct rdma_cm_id *cma_id)
{
        struct rdma_conn_param conn_param;
        int    ret;
        struct iser_cm_hdr req_hdr;
        struct iser_conn *iser_conn = (struct iser_conn *)cma_id->context;
        struct ib_conn *ib_conn = &iser_conn->ib_conn;
        struct iser_device *device = ib_conn->device;

        if (iser_conn->state != ISER_CONN_PENDING)
                /* bailout */
                return;

        ret = iser_create_ib_conn_res(ib_conn);
        if (ret)
                goto failure;

        memset(&conn_param, 0, sizeof conn_param);
        conn_param.responder_resources = device->dev_attr.max_qp_rd_atom;
        conn_param.initiator_depth     = 1;
        conn_param.retry_count         = 7;
        conn_param.rnr_retry_count     = 6;

        memset(&req_hdr, 0, sizeof(req_hdr));
        req_hdr.flags = (ISER_ZBVA_NOT_SUPPORTED |
                        ISER_SEND_W_INV_NOT_SUPPORTED);
        conn_param.private_data         = (void *)&req_hdr;
        conn_param.private_data_len     = sizeof(struct iser_cm_hdr);

        ret = rdma_connect(cma_id, &conn_param);
        if (ret) {
                iser_err("failure connecting: %d\n", ret);
                goto failure;
        }

        return;
failure:
        iser_connect_error(cma_id);
}

static void iser_connected_handler(struct rdma_cm_id *cma_id)
{
        struct iser_conn *iser_conn;
        struct ib_qp_attr attr;
        struct ib_qp_init_attr init_attr;

        iser_conn = (struct iser_conn *)cma_id->context;
        if (iser_conn->state != ISER_CONN_PENDING)
                /* bailout */
                return;

        (void)ib_query_qp(cma_id->qp, &attr, ~0, &init_attr);
        iser_info("remote qpn:%x my qpn:%x\n", attr.dest_qp_num, cma_id->qp->qp_num);

        iser_conn->state = ISER_CONN_UP;
        complete(&iser_conn->up_completion);
}

static void iser_disconnected_handler(struct rdma_cm_id *cma_id)
{
        struct iser_conn *iser_conn = (struct iser_conn *)cma_id->context;

        if (iser_conn_terminate(iser_conn)) {
                if (iser_conn->iscsi_conn)
                        iscsi_conn_failure(iser_conn->iscsi_conn,
                                           ISCSI_ERR_CONN_FAILED);
                else
                        iser_err("iscsi_iser connection isn't bound\n");
        }
}

static void iser_cleanup_handler(struct rdma_cm_id *cma_id,
                                 bool destroy)
{
        struct iser_conn *iser_conn = (struct iser_conn *)cma_id->context;

        /*
         * We are not guaranteed that we visited disconnected_handler
         * by now, call it here to be safe that we handle CM drep
         * and flush errors.
         */
        iser_disconnected_handler(cma_id);
        iser_free_ib_conn_res(iser_conn, destroy);
        complete(&iser_conn->ib_completion);
};

static int iser_cma_handler(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
{
        struct iser_conn *iser_conn;
        int ret = 0;

        iser_conn = (struct iser_conn *)cma_id->context;
        iser_info("%s (%d): status %d conn %p id %p\n",
                  rdma_event_msg(event->event), event->event,
                  event->status, cma_id->context, cma_id);

        mutex_lock(&iser_conn->state_mutex);
        switch (event->event) {
        case RDMA_CM_EVENT_ADDR_RESOLVED:
                iser_addr_handler(cma_id);
                break;
        case RDMA_CM_EVENT_ROUTE_RESOLVED:
                iser_route_handler(cma_id);
                break;
        case RDMA_CM_EVENT_ESTABLISHED:
                iser_connected_handler(cma_id);
                break;
        case RDMA_CM_EVENT_ADDR_ERROR:
        case RDMA_CM_EVENT_ROUTE_ERROR:
        case RDMA_CM_EVENT_CONNECT_ERROR:
        case RDMA_CM_EVENT_UNREACHABLE:
        case RDMA_CM_EVENT_REJECTED:
                iser_connect_error(cma_id);
                break;
        case RDMA_CM_EVENT_DISCONNECTED:
        case RDMA_CM_EVENT_ADDR_CHANGE:
        case RDMA_CM_EVENT_TIMEWAIT_EXIT:
                iser_cleanup_handler(cma_id, false);
                break;
        case RDMA_CM_EVENT_DEVICE_REMOVAL:
                /*
                 * we *must* destroy the device as we cannot rely
                 * on iscsid to be around to initiate error handling.
                 * also if we are not in state DOWN implicitly destroy
                 * the cma_id.
                 */
                iser_cleanup_handler(cma_id, true);
                if (iser_conn->state != ISER_CONN_DOWN) {
                        iser_conn->ib_conn.cma_id = NULL;
                        ret = 1;
                }
                break;
        default:
                iser_err("Unexpected RDMA CM event: %s (%d)\n",
                         rdma_event_msg(event->event), event->event);
                break;
        }
        mutex_unlock(&iser_conn->state_mutex);

        return ret;
}

void iser_conn_init(struct iser_conn *iser_conn)
{
        iser_conn->state = ISER_CONN_INIT;
        iser_conn->ib_conn.post_recv_buf_count = 0;
        init_completion(&iser_conn->ib_conn.flush_comp);
        init_completion(&iser_conn->stop_completion);
        init_completion(&iser_conn->ib_completion);
        init_completion(&iser_conn->up_completion);
        INIT_LIST_HEAD(&iser_conn->conn_list);
        mutex_init(&iser_conn->state_mutex);
}

 /**
 * starts the process of connecting to the target
 * sleeps until the connection is established or rejected
 */
int iser_connect(struct iser_conn   *iser_conn,
                 struct sockaddr    *src_addr,
                 struct sockaddr    *dst_addr,
                 int                 non_blocking)
{
        struct ib_conn *ib_conn = &iser_conn->ib_conn;
        int err = 0;

        mutex_lock(&iser_conn->state_mutex);

        sprintf(iser_conn->name, "%pISp", dst_addr);

        iser_info("connecting to: %s\n", iser_conn->name);

        /* the device is known only --after-- address resolution */
        ib_conn->device = NULL;

        iser_conn->state = ISER_CONN_PENDING;

        ib_conn->beacon.wr_id = ISER_BEACON_WRID;
        ib_conn->beacon.opcode = IB_WR_SEND;

        ib_conn->cma_id = rdma_create_id(&init_net, iser_cma_handler,
                                         (void *)iser_conn,
                                         RDMA_PS_TCP, IB_QPT_RC);
        if (IS_ERR(ib_conn->cma_id)) {
                err = PTR_ERR(ib_conn->cma_id);
                iser_err("rdma_create_id failed: %d\n", err);
                goto id_failure;
        }

        err = rdma_resolve_addr(ib_conn->cma_id, src_addr, dst_addr, 1000);
        if (err) {
                iser_err("rdma_resolve_addr failed: %d\n", err);
                goto addr_failure;
        }

        if (!non_blocking) {
                wait_for_completion_interruptible(&iser_conn->up_completion);

                if (iser_conn->state != ISER_CONN_UP) {
                        err =  -EIO;
                        goto connect_failure;
                }
        }
        mutex_unlock(&iser_conn->state_mutex);

        mutex_lock(&ig.connlist_mutex);
        list_add(&iser_conn->conn_list, &ig.connlist);
        mutex_unlock(&ig.connlist_mutex);
        return 0;

id_failure:
        ib_conn->cma_id = NULL;
addr_failure:
        iser_conn->state = ISER_CONN_DOWN;
connect_failure:
        mutex_unlock(&iser_conn->state_mutex);
        iser_conn_release(iser_conn);
        return err;
}

int iser_post_recvl(struct iser_conn *iser_conn)
{
        struct ib_recv_wr rx_wr, *rx_wr_failed;
        struct ib_conn *ib_conn = &iser_conn->ib_conn;
        struct ib_sge     sge;
        int ib_ret;

        sge.addr   = iser_conn->login_resp_dma;
        sge.length = ISER_RX_LOGIN_SIZE;
        sge.lkey   = ib_conn->device->pd->local_dma_lkey;

        rx_wr.wr_id   = (uintptr_t)iser_conn->login_resp_buf;
        rx_wr.sg_list = &sge;
        rx_wr.num_sge = 1;
        rx_wr.next    = NULL;

        ib_conn->post_recv_buf_count++;
        ib_ret  = ib_post_recv(ib_conn->qp, &rx_wr, &rx_wr_failed);
        if (ib_ret) {
                iser_err("ib_post_recv failed ret=%d\n", ib_ret);
                ib_conn->post_recv_buf_count--;
        }
        return ib_ret;
}

int iser_post_recvm(struct iser_conn *iser_conn, int count)
{
        struct ib_recv_wr *rx_wr, *rx_wr_failed;
        int i, ib_ret;
        struct ib_conn *ib_conn = &iser_conn->ib_conn;
        unsigned int my_rx_head = iser_conn->rx_desc_head;
        struct iser_rx_desc *rx_desc;

        for (rx_wr = ib_conn->rx_wr, i = 0; i < count; i++, rx_wr++) {
                rx_desc         = &iser_conn->rx_descs[my_rx_head];
                rx_wr->wr_id    = (uintptr_t)rx_desc;
                rx_wr->sg_list  = &rx_desc->rx_sg;
                rx_wr->num_sge  = 1;
                rx_wr->next     = rx_wr + 1;
                my_rx_head = (my_rx_head + 1) & iser_conn->qp_max_recv_dtos_mask;
        }

        rx_wr--;
        rx_wr->next = NULL; /* mark end of work requests list */

        ib_conn->post_recv_buf_count += count;
        ib_ret  = ib_post_recv(ib_conn->qp, ib_conn->rx_wr, &rx_wr_failed);
        if (ib_ret) {
                iser_err("ib_post_recv failed ret=%d\n", ib_ret);
                ib_conn->post_recv_buf_count -= count;
        } else
                iser_conn->rx_desc_head = my_rx_head;
        return ib_ret;
}


/**
 * iser_start_send - Initiate a Send DTO operation
 *
 * returns 0 on success, -1 on failure
 */
int iser_post_send(struct ib_conn *ib_conn, struct iser_tx_desc *tx_desc,
                   bool signal)
{
        struct ib_send_wr *bad_wr, *wr = iser_tx_next_wr(tx_desc);
        int ib_ret;

        ib_dma_sync_single_for_device(ib_conn->device->ib_device,
                                      tx_desc->dma_addr, ISER_HEADERS_LEN,
                                      DMA_TO_DEVICE);

        wr->next = NULL;
        wr->wr_id = (uintptr_t)tx_desc;
        wr->sg_list = tx_desc->tx_sg;
        wr->num_sge = tx_desc->num_sge;
        wr->opcode = IB_WR_SEND;
        wr->send_flags = signal ? IB_SEND_SIGNALED : 0;

        ib_ret = ib_post_send(ib_conn->qp, &tx_desc->wrs[0].send, &bad_wr);
        if (ib_ret)
                iser_err("ib_post_send failed, ret:%d opcode:%d\n",
                         ib_ret, bad_wr->opcode);

        return ib_ret;
}

/**
 * is_iser_tx_desc - Indicate if the completion wr_id
 *     is a TX descriptor or not.
 * @iser_conn: iser connection
 * @wr_id: completion WR identifier
 *
 * Since we cannot rely on wc opcode in FLUSH errors
 * we must work around it by checking if the wr_id address
 * falls in the iser connection rx_descs buffer. If so
 * it is an RX descriptor, otherwize it is a TX.
 */
static inline bool
is_iser_tx_desc(struct iser_conn *iser_conn, void *wr_id)
{
        void *start = iser_conn->rx_descs;
        int len = iser_conn->num_rx_descs * sizeof(*iser_conn->rx_descs);

        if (wr_id >= start && wr_id < start + len)
                return false;

        return true;
}

/**
 * iser_handle_comp_error() - Handle error completion
 * @ib_conn:   connection RDMA resources
 * @wc:        work completion
 *
 * Notes: We may handle a FLUSH error completion and in this case
 *        we only cleanup in case TX type was DATAOUT. For non-FLUSH
 *        error completion we should also notify iscsi layer that
 *        connection is failed (in case we passed bind stage).
 */
static void
iser_handle_comp_error(struct ib_conn *ib_conn,
                       struct ib_wc *wc)
{
        void *wr_id = (void *)(uintptr_t)wc->wr_id;
        struct iser_conn *iser_conn = container_of(ib_conn, struct iser_conn,
                                                   ib_conn);

        if (wc->status != IB_WC_WR_FLUSH_ERR)
                if (iser_conn->iscsi_conn)
                        iscsi_conn_failure(iser_conn->iscsi_conn,
                                           ISCSI_ERR_CONN_FAILED);

        if (wc->wr_id == ISER_FASTREG_LI_WRID)
                return;

        if (is_iser_tx_desc(iser_conn, wr_id)) {
                struct iser_tx_desc *desc = wr_id;

                if (desc->type == ISCSI_TX_DATAOUT)
                        kmem_cache_free(ig.desc_cache, desc);
        } else {
                ib_conn->post_recv_buf_count--;
        }
}

/**
 * iser_handle_wc - handle a single work completion
 * @wc: work completion
 *
 * Soft-IRQ context, work completion can be either
 * SEND or RECV, and can turn out successful or
 * with error (or flush error).
 */
static void iser_handle_wc(struct ib_wc *wc)
{
        struct ib_conn *ib_conn;
        struct iser_tx_desc *tx_desc;
        struct iser_rx_desc *rx_desc;

        ib_conn = wc->qp->qp_context;
        if (likely(wc->status == IB_WC_SUCCESS)) {
                if (wc->opcode == IB_WC_RECV) {
                        rx_desc = (struct iser_rx_desc *)(uintptr_t)wc->wr_id;
                        iser_rcv_completion(rx_desc, wc->byte_len,
                                            ib_conn);
                } else
                if (wc->opcode == IB_WC_SEND) {
                        tx_desc = (struct iser_tx_desc *)(uintptr_t)wc->wr_id;
                        iser_snd_completion(tx_desc, ib_conn);
                } else {
                        iser_err("Unknown wc opcode %d\n", wc->opcode);
                }
        } else {
                if (wc->status != IB_WC_WR_FLUSH_ERR)
                        iser_err("%s (%d): wr id %llx vend_err %x\n",
                                 ib_wc_status_msg(wc->status), wc->status,
                                 wc->wr_id, wc->vendor_err);
                else
                        iser_dbg("%s (%d): wr id %llx\n",
                                 ib_wc_status_msg(wc->status), wc->status,
                                 wc->wr_id);

                if (wc->wr_id == ISER_BEACON_WRID)
                        /* all flush errors were consumed */
                        complete(&ib_conn->flush_comp);
                else
                        iser_handle_comp_error(ib_conn, wc);
        }
}

/**
 * iser_cq_tasklet_fn - iSER completion polling loop
 * @data: iSER completion context
 *
 * Soft-IRQ context, polling connection CQ until
 * either CQ was empty or we exausted polling budget
 */
static void iser_cq_tasklet_fn(unsigned long data)
{
        struct iser_comp *comp = (struct iser_comp *)data;
        struct ib_cq *cq = comp->cq;
        struct ib_wc *const wcs = comp->wcs;
        int i, n, completed = 0;

        while ((n = ib_poll_cq(cq, ARRAY_SIZE(comp->wcs), wcs)) > 0) {
                for (i = 0; i < n; i++)
                        iser_handle_wc(&wcs[i]);

                completed += n;
                if (completed >= iser_cq_poll_limit)
                        break;
        }

        /*
         * It is assumed here that arming CQ only once its empty
         * would not cause interrupts to be missed.
         */
        ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);

        iser_dbg("got %d completions\n", completed);
}

static void iser_cq_callback(struct ib_cq *cq, void *cq_context)
{
        struct iser_comp *comp = cq_context;

        tasklet_schedule(&comp->tasklet);
}

u8 iser_check_task_pi_status(struct iscsi_iser_task *iser_task,
                             enum iser_data_dir cmd_dir, sector_t *sector)
{
        struct iser_mem_reg *reg = &iser_task->rdma_reg[cmd_dir];
        struct iser_fr_desc *desc = reg->mem_h;
        unsigned long sector_size = iser_task->sc->device->sector_size;
        struct ib_mr_status mr_status;
        int ret;

        if (desc && desc->pi_ctx->sig_protected) {
                desc->pi_ctx->sig_protected = 0;
                ret = ib_check_mr_status(desc->pi_ctx->sig_mr,
                                         IB_MR_CHECK_SIG_STATUS, &mr_status);
                if (ret) {
                        pr_err("ib_check_mr_status failed, ret %d\n", ret);
                        goto err;
                }

                if (mr_status.fail_status & IB_MR_CHECK_SIG_STATUS) {
                        sector_t sector_off = mr_status.sig_err.sig_err_offset;

                        sector_div(sector_off, sector_size + 8);
                        *sector = scsi_get_lba(iser_task->sc) + sector_off;

                        pr_err("PI error found type %d at sector %llx "
                               "expected %x vs actual %x\n",
                               mr_status.sig_err.err_type,
                               (unsigned long long)*sector,
                               mr_status.sig_err.expected,
                               mr_status.sig_err.actual);

                        switch (mr_status.sig_err.err_type) {
                        case IB_SIG_BAD_GUARD:
                                return 0x1;
                        case IB_SIG_BAD_REFTAG:
                                return 0x3;
                        case IB_SIG_BAD_APPTAG:
                                return 0x2;
                        }
                }
        }

        return 0;
err:
        /* Not alot we can do here, return ambiguous guard error */
        return 0x1;
}