IB/iser: iSER initiator iSCSI PDU and TX/RX

This file contains the iSER initiator processing of iSCSI PDUs - controls,
commands and data-outs along with processing of TX and RX completions.
It interacts with the lower level iser code doing the memory registration
and and the cma and verbs calls.

Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 738 insertions, 0 deletions

diff --git a/drivers/infiniband/ulp/iser/iser_initiator.c b/drivers/infiniband/ulp/iser/iser_initiator.c
new file mode 100644
index 000000000000..ccf56f6f7236
--- /dev/null
+++ b/drivers/infiniband/ulp/iser/iser_initiator.c
@@ -0,0 +1,738 @@
+/*
+ * Copyright (c) 2004, 2005, 2006 Voltaire, Inc. 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.
+ *
+ * $Id: iser_initiator.c 6964 2006-05-07 11:11:43Z ogerlitz $
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <asm/io.h>
+#include <asm/scatterlist.h>
+#include <linux/scatterlist.h>
+#include <linux/kfifo.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_host.h>
+
+#include "iscsi_iser.h"
+
+/* Constant PDU lengths calculations */
+#define ISER_TOTAL_HEADERS_LEN  (sizeof (struct iser_hdr) + \
+                                 sizeof (struct iscsi_hdr))
+
+/* iser_dto_add_regd_buff - increments the reference count for *
+ * the registered buffer & adds it to the DTO object           */
+static void iser_dto_add_regd_buff(struct iser_dto *dto,
+                                   struct iser_regd_buf *regd_buf,
+                                   unsigned long use_offset,
+                                   unsigned long use_size)
+{
+        int add_idx;
+
+        atomic_inc(&regd_buf->ref_count);
+
+        add_idx = dto->regd_vector_len;
+        dto->regd[add_idx] = regd_buf;
+        dto->used_sz[add_idx] = use_size;
+        dto->offset[add_idx] = use_offset;
+
+        dto->regd_vector_len++;
+}
+
+static int iser_dma_map_task_data(struct iscsi_iser_cmd_task *iser_ctask,
+                                  struct iser_data_buf       *data,
+                                  enum   iser_data_dir       iser_dir,
+                                  enum   dma_data_direction  dma_dir)
+{
+        struct device *dma_device;
+
+        iser_ctask->dir[iser_dir] = 1;
+        dma_device = iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
+
+        data->dma_nents = dma_map_sg(dma_device, data->buf, data->size, dma_dir);
+        if (data->dma_nents == 0) {
+                iser_err("dma_map_sg failed!!!\n");
+                return -EINVAL;
+        }
+        return 0;
+}
+
+static void iser_dma_unmap_task_data(struct iscsi_iser_cmd_task *iser_ctask)
+{
+        struct device  *dma_device;
+        struct iser_data_buf *data;
+
+        dma_device = iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
+
+        if (iser_ctask->dir[ISER_DIR_IN]) {
+                data = &iser_ctask->data[ISER_DIR_IN];
+                dma_unmap_sg(dma_device, data->buf, data->size, DMA_FROM_DEVICE);
+        }
+
+        if (iser_ctask->dir[ISER_DIR_OUT]) {
+                data = &iser_ctask->data[ISER_DIR_OUT];
+                dma_unmap_sg(dma_device, data->buf, data->size, DMA_TO_DEVICE);
+        }
+}
+
+/* Register user buffer memory and initialize passive rdma
+ *  dto descriptor. Total data size is stored in
+ *  iser_ctask->data[ISER_DIR_IN].data_len
+ */
+static int iser_prepare_read_cmd(struct iscsi_cmd_task *ctask,
+                                 unsigned int edtl)
+
+{
+        struct iscsi_iser_cmd_task *iser_ctask = ctask->dd_data;
+        struct iser_regd_buf *regd_buf;
+        int err;
+        struct iser_hdr *hdr = &iser_ctask->desc.iser_header;
+        struct iser_data_buf *buf_in = &iser_ctask->data[ISER_DIR_IN];
+
+        err = iser_dma_map_task_data(iser_ctask,
+                                     buf_in,
+                                     ISER_DIR_IN,
+                                     DMA_FROM_DEVICE);
+        if (err)
+                return err;
+
+        if (edtl > iser_ctask->data[ISER_DIR_IN].data_len) {
+                iser_err("Total data length: %ld, less than EDTL: "
+                         "%d, in READ cmd BHS itt: %d, conn: 0x%p\n",
+                         iser_ctask->data[ISER_DIR_IN].data_len, edtl,
+                         ctask->itt, iser_ctask->iser_conn);
+                return -EINVAL;
+        }
+
+        err = iser_reg_rdma_mem(iser_ctask,ISER_DIR_IN);
+        if (err) {
+                iser_err("Failed to set up Data-IN RDMA\n");
+                return err;
+        }
+        regd_buf = &iser_ctask->rdma_regd[ISER_DIR_IN];
+
+        hdr->flags    |= ISER_RSV;
+        hdr->read_stag = cpu_to_be32(regd_buf->reg.rkey);
+        hdr->read_va   = cpu_to_be64(regd_buf->reg.va);
+
+        iser_dbg("Cmd itt:%d READ tags RKEY:%#.4X VA:%#llX\n",
+                 ctask->itt, regd_buf->reg.rkey,
+                 (unsigned long long)regd_buf->reg.va);
+
+        return 0;
+}
+
+/* Register user buffer memory and initialize passive rdma
+ *  dto descriptor. Total data size is stored in
+ *  ctask->data[ISER_DIR_OUT].data_len
+ */
+static int
+iser_prepare_write_cmd(struct iscsi_cmd_task *ctask,
+                       unsigned int imm_sz,
+                       unsigned int unsol_sz,
+                       unsigned int edtl)
+{
+        struct iscsi_iser_cmd_task *iser_ctask = ctask->dd_data;
+        struct iser_regd_buf *regd_buf;
+        int err;
+        struct iser_dto *send_dto = &iser_ctask->desc.dto;
+        struct iser_hdr *hdr = &iser_ctask->desc.iser_header;
+        struct iser_data_buf *buf_out = &iser_ctask->data[ISER_DIR_OUT];
+
+        err = iser_dma_map_task_data(iser_ctask,
+                                     buf_out,
+                                     ISER_DIR_OUT,
+                                     DMA_TO_DEVICE);
+        if (err)
+                return err;
+
+        if (edtl > iser_ctask->data[ISER_DIR_OUT].data_len) {
+                iser_err("Total data length: %ld, less than EDTL: %d, "
+                         "in WRITE cmd BHS itt: %d, conn: 0x%p\n",
+                         iser_ctask->data[ISER_DIR_OUT].data_len,
+                         edtl, ctask->itt, ctask->conn);
+                return -EINVAL;
+        }
+
+        err = iser_reg_rdma_mem(iser_ctask,ISER_DIR_OUT);
+        if (err != 0) {
+                iser_err("Failed to register write cmd RDMA mem\n");
+                return err;
+        }
+
+        regd_buf = &iser_ctask->rdma_regd[ISER_DIR_OUT];
+
+        if (unsol_sz < edtl) {
+                hdr->flags     |= ISER_WSV;
+                hdr->write_stag = cpu_to_be32(regd_buf->reg.rkey);
+                hdr->write_va   = cpu_to_be64(regd_buf->reg.va + unsol_sz);
+
+                iser_dbg("Cmd itt:%d, WRITE tags, RKEY:%#.4X "
+                         "VA:%#llX + unsol:%d\n",
+                         ctask->itt, regd_buf->reg.rkey,
+                         (unsigned long long)regd_buf->reg.va, unsol_sz);
+        }
+
+        if (imm_sz > 0) {
+                iser_dbg("Cmd itt:%d, WRITE, adding imm.data sz: %d\n",
+                         ctask->itt, imm_sz);
+                iser_dto_add_regd_buff(send_dto,
+                                       regd_buf,
+                                       0,
+                                       imm_sz);
+        }
+
+        return 0;
+}
+
+/**
+ * iser_post_receive_control - allocates, initializes and posts receive DTO.
+ */
+static int iser_post_receive_control(struct iscsi_conn *conn)
+{
+        struct iscsi_iser_conn *iser_conn = conn->dd_data;
+        struct iser_desc     *rx_desc;
+        struct iser_regd_buf *regd_hdr;
+        struct iser_regd_buf *regd_data;
+        struct iser_dto      *recv_dto = NULL;
+        struct iser_device  *device = iser_conn->ib_conn->device;
+        int rx_data_size, err = 0;
+
+        rx_desc = kmem_cache_alloc(ig.desc_cache, GFP_NOIO);
+        if (rx_desc == NULL) {
+                iser_err("Failed to alloc desc for post recv\n");
+                return -ENOMEM;
+        }
+        rx_desc->type = ISCSI_RX;
+
+        /* for the login sequence we must support rx of upto 8K; login is done
+         * after conn create/bind (connect) and conn stop/bind (reconnect),
+         * what's common for both schemes is that the connection is not started
+         */
+        if (conn->c_stage != ISCSI_CONN_STARTED)
+                rx_data_size = DEFAULT_MAX_RECV_DATA_SEGMENT_LENGTH;
+        else /* FIXME till user space sets conn->max_recv_dlength correctly */
+                rx_data_size = 128;
+
+        rx_desc->data = kmalloc(rx_data_size, GFP_NOIO);
+        if (rx_desc->data == NULL) {
+                iser_err("Failed to alloc data buf for post recv\n");
+                err = -ENOMEM;
+                goto post_rx_kmalloc_failure;
+        }
+
+        recv_dto = &rx_desc->dto;
+        recv_dto->conn          = iser_conn;
+        recv_dto->regd_vector_len = 0;
+
+        regd_hdr = &rx_desc->hdr_regd_buf;
+        memset(regd_hdr, 0, sizeof(struct iser_regd_buf));
+        regd_hdr->device  = device;
+        regd_hdr->virt_addr  = rx_desc; /* == &rx_desc->iser_header */
+        regd_hdr->data_size  = ISER_TOTAL_HEADERS_LEN;
+
+        iser_reg_single(device, regd_hdr, DMA_FROM_DEVICE);
+
+        iser_dto_add_regd_buff(recv_dto, regd_hdr, 0, 0);
+
+        regd_data = &rx_desc->data_regd_buf;
+        memset(regd_data, 0, sizeof(struct iser_regd_buf));
+        regd_data->device  = device;
+        regd_data->virt_addr  = rx_desc->data;
+        regd_data->data_size  = rx_data_size;
+
+        iser_reg_single(device, regd_data, DMA_FROM_DEVICE);
+
+        iser_dto_add_regd_buff(recv_dto, regd_data, 0, 0);
+
+        err = iser_post_recv(rx_desc);
+        if (!err)
+                return 0;
+
+        /* iser_post_recv failed */
+        iser_dto_buffs_release(recv_dto);
+        kfree(rx_desc->data);
+post_rx_kmalloc_failure:
+        kmem_cache_free(ig.desc_cache, rx_desc);
+        return err;
+}
+
+/* creates a new tx descriptor and adds header regd buffer */
+static void iser_create_send_desc(struct iscsi_iser_conn *iser_conn,
+                                  struct iser_desc       *tx_desc)
+{
+        struct iser_regd_buf *regd_hdr = &tx_desc->hdr_regd_buf;
+        struct iser_dto      *send_dto = &tx_desc->dto;
+
+        memset(regd_hdr, 0, sizeof(struct iser_regd_buf));
+        regd_hdr->device  = iser_conn->ib_conn->device;
+        regd_hdr->virt_addr  = tx_desc; /* == &tx_desc->iser_header */
+        regd_hdr->data_size  = ISER_TOTAL_HEADERS_LEN;
+
+        send_dto->conn          = iser_conn;
+        send_dto->notify_enable   = 1;
+        send_dto->regd_vector_len = 0;
+
+        memset(&tx_desc->iser_header, 0, sizeof(struct iser_hdr));
+        tx_desc->iser_header.flags = ISER_VER;
+
+        iser_dto_add_regd_buff(send_dto, regd_hdr, 0, 0);
+}
+
+/**
+ *  iser_conn_set_full_featured_mode - (iSER API)
+ */
+int iser_conn_set_full_featured_mode(struct iscsi_conn *conn)
+{
+        struct iscsi_iser_conn *iser_conn = conn->dd_data;
+
+        int i;
+        /* no need to keep it in a var, we are after login so if this should
+         * be negotiated, by now the result should be available here */
+        int initial_post_recv_bufs_num = ISER_MAX_RX_MISC_PDUS;
+
+        iser_dbg("Initially post: %d\n", initial_post_recv_bufs_num);
+
+        /* Check that there is no posted recv or send buffers left - */
+        /* they must be consumed during the login phase */
+        BUG_ON(atomic_read(&iser_conn->ib_conn->post_recv_buf_count) != 0);
+        BUG_ON(atomic_read(&iser_conn->ib_conn->post_send_buf_count) != 0);
+
+        /* Initial post receive buffers */
+        for (i = 0; i < initial_post_recv_bufs_num; i++) {
+                if (iser_post_receive_control(conn) != 0) {
+                        iser_err("Failed to post recv bufs at:%d conn:0x%p\n",
+                                 i, conn);
+                        return -ENOMEM;
+                }
+        }
+        iser_dbg("Posted %d post recv bufs, conn:0x%p\n", i, conn);
+        return 0;
+}
+
+static int
+iser_check_xmit(struct iscsi_conn *conn, void *task)
+{
+        int rc = 0;
+        struct iscsi_iser_conn *iser_conn = conn->dd_data;
+
+        write_lock_bh(conn->recv_lock);
+        if (atomic_read(&iser_conn->ib_conn->post_send_buf_count) ==
+            ISER_QP_MAX_REQ_DTOS) {
+                iser_dbg("%ld can't xmit task %p, suspending tx\n",jiffies,task);
+                set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
+                rc = -EAGAIN;
+        }
+        write_unlock_bh(conn->recv_lock);
+        return rc;
+}
+
+
+/**
+ * iser_send_command - send command PDU
+ */
+int iser_send_command(struct iscsi_conn     *conn,
+                      struct iscsi_cmd_task *ctask)
+{
+        struct iscsi_iser_conn *iser_conn = conn->dd_data;
+        struct iscsi_iser_cmd_task *iser_ctask = ctask->dd_data;
+        struct iser_dto *send_dto = NULL;
+        unsigned long edtl;
+        int err = 0;
+        struct iser_data_buf *data_buf;
+
+        struct iscsi_cmd *hdr =  ctask->hdr;
+        struct scsi_cmnd *sc  =  ctask->sc;
+
+        if (!iser_conn_state_comp(iser_conn->ib_conn, ISER_CONN_UP)) {
+                iser_err("Failed to send, conn: 0x%p is not up\n", iser_conn->ib_conn);
+                return -EPERM;
+        }
+        if (iser_check_xmit(conn, ctask))
+                return -EAGAIN;
+
+        edtl = ntohl(hdr->data_length);
+
+        /* build the tx desc regd header and add it to the tx desc dto */
+        iser_ctask->desc.type = ISCSI_TX_SCSI_COMMAND;
+        send_dto = &iser_ctask->desc.dto;
+        send_dto->ctask = iser_ctask;
+        iser_create_send_desc(iser_conn, &iser_ctask->desc);
+
+        if (hdr->flags & ISCSI_FLAG_CMD_READ)
+                data_buf = &iser_ctask->data[ISER_DIR_IN];
+        else
+                data_buf = &iser_ctask->data[ISER_DIR_OUT];
+
+        if (sc->use_sg) { /* using a scatter list */
+                data_buf->buf  = sc->request_buffer;
+                data_buf->size = sc->use_sg;
+        } else if (sc->request_bufflen) {
+                /* using a single buffer - convert it into one entry SG */
+                sg_init_one(&data_buf->sg_single,
+                            sc->request_buffer, sc->request_bufflen);
+                data_buf->buf   = &data_buf->sg_single;
+                data_buf->size  = 1;
+        }
+
+        data_buf->data_len = sc->request_bufflen;
+
+        if (hdr->flags & ISCSI_FLAG_CMD_READ) {
+                err = iser_prepare_read_cmd(ctask, edtl);
+                if (err)
+                        goto send_command_error;
+        }
+        if (hdr->flags & ISCSI_FLAG_CMD_WRITE) {
+                err = iser_prepare_write_cmd(ctask,
+                                             ctask->imm_count,
+                                             ctask->imm_count +
+                                             ctask->unsol_count,
+                                             edtl);
+                if (err)
+                        goto send_command_error;
+        }
+
+        iser_reg_single(iser_conn->ib_conn->device,
+                        send_dto->regd[0], DMA_TO_DEVICE);
+
+        if (iser_post_receive_control(conn) != 0) {
+                iser_err("post_recv failed!\n");
+                err = -ENOMEM;
+                goto send_command_error;
+        }
+
+        iser_ctask->status = ISER_TASK_STATUS_STARTED;
+
+        err = iser_post_send(&iser_ctask->desc);
+        if (!err)
+                return 0;
+
+send_command_error:
+        iser_dto_buffs_release(send_dto);
+        iser_err("conn %p failed ctask->itt %d err %d\n",conn, ctask->itt, err);
+        return err;
+}
+
+/**
+ * iser_send_data_out - send data out PDU
+ */
+int iser_send_data_out(struct iscsi_conn     *conn,
+                       struct iscsi_cmd_task *ctask,
+                       struct iscsi_data *hdr)
+{
+        struct iscsi_iser_conn *iser_conn = conn->dd_data;
+        struct iscsi_iser_cmd_task *iser_ctask = ctask->dd_data;
+        struct iser_desc *tx_desc = NULL;
+        struct iser_dto *send_dto = NULL;
+        unsigned long buf_offset;
+        unsigned long data_seg_len;
+        unsigned int itt;
+        int err = 0;
+
+        if (!iser_conn_state_comp(iser_conn->ib_conn, ISER_CONN_UP)) {
+                iser_err("Failed to send, conn: 0x%p is not up\n", iser_conn->ib_conn);
+                return -EPERM;
+        }
+
+        if (iser_check_xmit(conn, ctask))
+                return -EAGAIN;
+
+        itt = ntohl(hdr->itt);
+        data_seg_len = ntoh24(hdr->dlength);
+        buf_offset   = ntohl(hdr->offset);
+
+        iser_dbg("%s itt %d dseg_len %d offset %d\n",
+                 __func__,(int)itt,(int)data_seg_len,(int)buf_offset);
+
+        tx_desc = kmem_cache_alloc(ig.desc_cache, GFP_NOIO);
+        if (tx_desc == NULL) {
+                iser_err("Failed to alloc desc for post dataout\n");
+                return -ENOMEM;
+        }
+
+        tx_desc->type = ISCSI_TX_DATAOUT;
+        memcpy(&tx_desc->iscsi_header, hdr, sizeof(struct iscsi_hdr));
+
+        /* build the tx desc regd header and add it to the tx desc dto */
+        send_dto = &tx_desc->dto;
+        send_dto->ctask = iser_ctask;
+        iser_create_send_desc(iser_conn, tx_desc);
+
+        iser_reg_single(iser_conn->ib_conn->device,
+                        send_dto->regd[0], DMA_TO_DEVICE);
+
+        /* all data was registered for RDMA, we can use the lkey */
+        iser_dto_add_regd_buff(send_dto,
+                               &iser_ctask->rdma_regd[ISER_DIR_OUT],
+                               buf_offset,
+                               data_seg_len);
+
+        if (buf_offset + data_seg_len > iser_ctask->data[ISER_DIR_OUT].data_len) {
+                iser_err("Offset:%ld & DSL:%ld in Data-Out "
+                         "inconsistent with total len:%ld, itt:%d\n",
+                         buf_offset, data_seg_len,
+                         iser_ctask->data[ISER_DIR_OUT].data_len, itt);
+                err = -EINVAL;
+                goto send_data_out_error;
+        }
+        iser_dbg("data-out itt: %d, offset: %ld, sz: %ld\n",
+                 itt, buf_offset, data_seg_len);
+
+
+        err = iser_post_send(tx_desc);
+        if (!err)
+                return 0;
+
+send_data_out_error:
+        iser_dto_buffs_release(send_dto);
+        kmem_cache_free(ig.desc_cache, tx_desc);
+        iser_err("conn %p failed err %d\n",conn, err);
+        return err;
+}
+
+int iser_send_control(struct iscsi_conn *conn,
+                      struct iscsi_mgmt_task *mtask)
+{
+        struct iscsi_iser_conn *iser_conn = conn->dd_data;
+        struct iser_desc *mdesc = mtask->dd_data;
+        struct iser_dto *send_dto = NULL;
+        unsigned int itt;
+        unsigned long data_seg_len;
+        int err = 0;
+        unsigned char opcode;
+        struct iser_regd_buf *regd_buf;
+        struct iser_device *device;
+
+        if (!iser_conn_state_comp(iser_conn->ib_conn, ISER_CONN_UP)) {
+                iser_err("Failed to send, conn: 0x%p is not up\n", iser_conn->ib_conn);
+                return -EPERM;
+        }
+
+        if (iser_check_xmit(conn,mtask))
+                return -EAGAIN;
+
+        /* build the tx desc regd header and add it to the tx desc dto */
+        mdesc->type = ISCSI_TX_CONTROL;
+        send_dto = &mdesc->dto;
+        send_dto->ctask = NULL;
+        iser_create_send_desc(iser_conn, mdesc);
+
+        device = iser_conn->ib_conn->device;
+
+        iser_reg_single(device, send_dto->regd[0], DMA_TO_DEVICE);
+
+        itt = ntohl(mtask->hdr->itt);
+        opcode = mtask->hdr->opcode & ISCSI_OPCODE_MASK;
+        data_seg_len = ntoh24(mtask->hdr->dlength);
+
+        if (data_seg_len > 0) {
+                regd_buf = &mdesc->data_regd_buf;
+                memset(regd_buf, 0, sizeof(struct iser_regd_buf));
+                regd_buf->device = device;
+                regd_buf->virt_addr = mtask->data;
+                regd_buf->data_size = mtask->data_count;
+                iser_reg_single(device, regd_buf,
+                                DMA_TO_DEVICE);
+                iser_dto_add_regd_buff(send_dto, regd_buf,
+                                       0,
+                                       data_seg_len);
+        }
+
+        if (iser_post_receive_control(conn) != 0) {
+                iser_err("post_rcv_buff failed!\n");
+                err = -ENOMEM;
+                goto send_control_error;
+        }
+
+        err = iser_post_send(mdesc);
+        if (!err)
+                return 0;
+
+send_control_error:
+        iser_dto_buffs_release(send_dto);
+        iser_err("conn %p failed err %d\n",conn, err);
+        return err;
+}
+
+/**
+ * iser_rcv_dto_completion - recv DTO completion
+ */
+void iser_rcv_completion(struct iser_desc *rx_desc,
+                         unsigned long dto_xfer_len)
+{
+        struct iser_dto        *dto = &rx_desc->dto;
+        struct iscsi_iser_conn *conn = dto->conn;
+        struct iscsi_session *session = conn->iscsi_conn->session;
+        struct iscsi_cmd_task *ctask;
+        struct iscsi_iser_cmd_task *iser_ctask;
+        struct iscsi_hdr *hdr;
+        char   *rx_data = NULL;
+        int     rx_data_len = 0;
+        unsigned int itt;
+        unsigned char opcode;
+
+        hdr = &rx_desc->iscsi_header;
+
+        iser_dbg("op 0x%x itt 0x%x\n", hdr->opcode,hdr->itt);
+
+        if (dto_xfer_len > ISER_TOTAL_HEADERS_LEN) { /* we have data */
+                rx_data_len = dto_xfer_len - ISER_TOTAL_HEADERS_LEN;
+                rx_data     = dto->regd[1]->virt_addr;
+                rx_data    += dto->offset[1];
+        }
+
+        opcode = hdr->opcode & ISCSI_OPCODE_MASK;
+
+        if (opcode == ISCSI_OP_SCSI_CMD_RSP) {
+                itt = hdr->itt & ISCSI_ITT_MASK; /* mask out cid and age bits */
+                if (!(itt < session->cmds_max))
+                        iser_err("itt can't be matched to task!!!"
+                                 "conn %p opcode %d cmds_max %d itt %d\n",
+                                 conn->iscsi_conn,opcode,session->cmds_max,itt);
+                /* use the mapping given with the cmds array indexed by itt */
+                ctask = (struct iscsi_cmd_task *)session->cmds[itt];
+                iser_ctask = ctask->dd_data;
+                iser_dbg("itt %d ctask %p\n",itt,ctask);
+                iser_ctask->status = ISER_TASK_STATUS_COMPLETED;
+                iser_ctask_rdma_finalize(iser_ctask);
+        }
+
+        iser_dto_buffs_release(dto);
+
+        iscsi_iser_recv(conn->iscsi_conn, hdr, rx_data, rx_data_len);
+
+        kfree(rx_desc->data);
+        kmem_cache_free(ig.desc_cache, rx_desc);
+
+        /* decrementing conn->post_recv_buf_count only --after-- freeing the   *
+         * task eliminates the need to worry on tasks which are completed in   *
+         * parallel to the execution of iser_conn_term. So the code that waits *
+         * for the posted rx bufs refcount to become zero handles everything   */
+        atomic_dec(&conn->ib_conn->post_recv_buf_count);
+}
+
+void iser_snd_completion(struct iser_desc *tx_desc)
+{
+        struct iser_dto        *dto = &tx_desc->dto;
+        struct iscsi_iser_conn *iser_conn = dto->conn;
+        struct iscsi_conn      *conn = iser_conn->iscsi_conn;
+        struct iscsi_mgmt_task *mtask;
+
+        iser_dbg("Initiator, Data sent dto=0x%p\n", dto);
+
+        iser_dto_buffs_release(dto);
+
+        if (tx_desc->type == ISCSI_TX_DATAOUT)
+                kmem_cache_free(ig.desc_cache, tx_desc);
+
+        atomic_dec(&iser_conn->ib_conn->post_send_buf_count);
+
+        write_lock(conn->recv_lock);
+        if (conn->suspend_tx) {
+                iser_dbg("%ld resuming tx\n",jiffies);
+                clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
+                scsi_queue_work(conn->session->host, &conn->xmitwork);
+        }
+        write_unlock(conn->recv_lock);
+
+        if (tx_desc->type == ISCSI_TX_CONTROL) {
+                /* this arithmetic is legal by libiscsi dd_data allocation */
+                mtask = (void *) ((long)(void *)tx_desc -
+                                  sizeof(struct iscsi_mgmt_task));
+                if (mtask->hdr->itt == cpu_to_be32(ISCSI_RESERVED_TAG)) {
+                        struct iscsi_session *session = conn->session;
+
+                        spin_lock(&conn->session->lock);
+                        list_del(&mtask->running);
+                        __kfifo_put(session->mgmtpool.queue, (void*)&mtask,
+                                    sizeof(void*));
+                        spin_unlock(&session->lock);
+                }
+        }
+}
+
+void iser_ctask_rdma_init(struct iscsi_iser_cmd_task *iser_ctask)
+
+{
+        iser_ctask->status = ISER_TASK_STATUS_INIT;
+
+        iser_ctask->dir[ISER_DIR_IN] = 0;
+        iser_ctask->dir[ISER_DIR_OUT] = 0;
+
+        iser_ctask->data[ISER_DIR_IN].data_len  = 0;
+        iser_ctask->data[ISER_DIR_OUT].data_len = 0;
+
+        memset(&iser_ctask->rdma_regd[ISER_DIR_IN], 0,
+               sizeof(struct iser_regd_buf));
+        memset(&iser_ctask->rdma_regd[ISER_DIR_OUT], 0,
+               sizeof(struct iser_regd_buf));
+}
+
+void iser_ctask_rdma_finalize(struct iscsi_iser_cmd_task *iser_ctask)
+{
+        int deferred;
+
+        /* if we were reading, copy back to unaligned sglist,
+         * anyway dma_unmap and free the copy
+         */
+        if (iser_ctask->data_copy[ISER_DIR_IN].copy_buf != NULL)
+                iser_finalize_rdma_unaligned_sg(iser_ctask, ISER_DIR_IN);
+        if (iser_ctask->data_copy[ISER_DIR_OUT].copy_buf != NULL)
+                iser_finalize_rdma_unaligned_sg(iser_ctask, ISER_DIR_OUT);
+
+        if (iser_ctask->dir[ISER_DIR_IN]) {
+                deferred = iser_regd_buff_release
+                        (&iser_ctask->rdma_regd[ISER_DIR_IN]);
+                if (deferred) {
+                        iser_err("References remain for BUF-IN rdma reg\n");
+                        BUG();
+                }
+        }
+
+        if (iser_ctask->dir[ISER_DIR_OUT]) {
+                deferred = iser_regd_buff_release
+                        (&iser_ctask->rdma_regd[ISER_DIR_OUT]);
+                if (deferred) {
+                        iser_err("References remain for BUF-OUT rdma reg\n");
+                        BUG();
+                }
+        }
+
+        iser_dma_unmap_task_data(iser_ctask);
+}
+
+void iser_dto_buffs_release(struct iser_dto *dto)
+{
+        int i;
+
+        for (i = 0; i < dto->regd_vector_len; i++)
+                iser_regd_buff_release(dto->regd[i]);
+}
+