IB/iser: Avoid recv buffer exhaustion caused by unexpected PDUs

[deliverable/linux.git] / drivers / infiniband / ulp / iser / iser_initiator.c

/*
 * 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.
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.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++;
}

/* Register user buffer memory and initialize passive rdma
 *  dto descriptor. Total data size is stored in
 *  iser_task->data[ISER_DIR_IN].data_len
 */
static int iser_prepare_read_cmd(struct iscsi_task *task,
				 unsigned int edtl)

{
	struct iscsi_iser_task *iser_task = task->dd_data;
	struct iser_regd_buf *regd_buf;
	int err;
	struct iser_hdr *hdr = &iser_task->desc.iser_header;
	struct iser_data_buf *buf_in = &iser_task->data[ISER_DIR_IN];

	err = iser_dma_map_task_data(iser_task,
				     buf_in,
				     ISER_DIR_IN,
				     DMA_FROM_DEVICE);
	if (err)
		return err;

	if (edtl > iser_task->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_task->data[ISER_DIR_IN].data_len, edtl,
			 task->itt, iser_task->iser_conn);
		return -EINVAL;
	}

	err = iser_reg_rdma_mem(iser_task,ISER_DIR_IN);
	if (err) {
		iser_err("Failed to set up Data-IN RDMA\n");
		return err;
	}
	regd_buf = &iser_task->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",
		 task->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
 *  task->data[ISER_DIR_OUT].data_len
 */
static int
iser_prepare_write_cmd(struct iscsi_task *task,
		       unsigned int imm_sz,
		       unsigned int unsol_sz,
		       unsigned int edtl)
{
	struct iscsi_iser_task *iser_task = task->dd_data;
	struct iser_regd_buf *regd_buf;
	int err;
	struct iser_dto *send_dto = &iser_task->desc.dto;
	struct iser_hdr *hdr = &iser_task->desc.iser_header;
	struct iser_data_buf *buf_out = &iser_task->data[ISER_DIR_OUT];

	err = iser_dma_map_task_data(iser_task,
				     buf_out,
				     ISER_DIR_OUT,
				     DMA_TO_DEVICE);
	if (err)
		return err;

	if (edtl > iser_task->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_task->data[ISER_DIR_OUT].data_len,
			 edtl, task->itt, task->conn);
		return -EINVAL;
	}

	err = iser_reg_rdma_mem(iser_task,ISER_DIR_OUT);
	if (err != 0) {
		iser_err("Failed to register write cmd RDMA mem\n");
		return err;
	}

	regd_buf = &iser_task->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",
			 task->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",
			 task->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;
	int posts, outstanding_unexp_pdus;

	/* 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 = ISCSI_DEF_MAX_RECV_SEG_LEN;
	else /* FIXME till user space sets conn->max_recv_dlength correctly */
		rx_data_size = 128;

	outstanding_unexp_pdus =
		atomic_xchg(&iser_conn->ib_conn->unexpected_pdu_count, 0);

	/*
	 * in addition to the response buffer, replace those consumed by
	 * unexpected pdus.
	 */
	for (posts = 0; posts < 1 + outstanding_unexp_pdus; posts++) {
		rx_desc = kmem_cache_alloc(ig.desc_cache, GFP_NOIO);
		if (rx_desc == NULL) {
			iser_err("Failed to alloc desc for post recv %d\n",
				 posts);
			err = -ENOMEM;
			goto post_rx_cache_alloc_failure;
		}
		rx_desc->type = ISCSI_RX;
		rx_desc->data = kmalloc(rx_data_size, GFP_NOIO);
		if (rx_desc->data == NULL) {
			iser_err("Failed to alloc data buf for post recv %d\n",
				 posts);
			err = -ENOMEM;
			goto post_rx_kmalloc_failure;
		}

		recv_dto = &rx_desc->dto;
		recv_dto->ib_conn = iser_conn->ib_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) {
			iser_err("Failed iser_post_recv for post %d\n", posts);
			goto post_rx_post_recv_failure;
		}
	}
	/* all posts successful */
	return 0;

post_rx_post_recv_failure:
	iser_dto_buffs_release(recv_dto);
	kfree(rx_desc->data);
post_rx_kmalloc_failure:
	kmem_cache_free(ig.desc_cache, rx_desc);
post_rx_cache_alloc_failure:
	if (posts > 0) {
		/*
		 * response buffer posted, but did not replace all unexpected
		 * pdu recv bufs. Ignore error, retry occurs next send
		 */
		outstanding_unexp_pdus -= (posts - 1);
		err = 0;
	}
	atomic_add(outstanding_unexp_pdus,
		   &iser_conn->ib_conn->unexpected_pdu_count);

	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->ib_conn         = iser_conn->ib_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;
	/*
	 * FIXME this value should be declared to the target during login with
	 * the MaxOutstandingUnexpectedPDUs key when supported
	 */
	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)
{
	struct iscsi_iser_conn *iser_conn = conn->dd_data;

	if (atomic_read(&iser_conn->ib_conn->post_send_buf_count) ==
	    ISER_QP_MAX_REQ_DTOS) {
		iser_dbg("%ld can't xmit task %p\n",jiffies,task);
		return -ENOBUFS;
	}
	return 0;
}


/**
 * iser_send_command - send command PDU
 */
int iser_send_command(struct iscsi_conn *conn,
		      struct iscsi_task *task)
{
	struct iscsi_iser_conn *iser_conn = conn->dd_data;
	struct iscsi_iser_task *iser_task = task->dd_data;
	struct iser_dto *send_dto = NULL;
	unsigned long edtl;
	int err = 0;
	struct iser_data_buf *data_buf;

	struct iscsi_cmd *hdr =  task->hdr;
	struct scsi_cmnd *sc  =  task->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, task))
		return -ENOBUFS;

	edtl = ntohl(hdr->data_length);

	/* build the tx desc regd header and add it to the tx desc dto */
	iser_task->desc.type = ISCSI_TX_SCSI_COMMAND;
	send_dto = &iser_task->desc.dto;
	send_dto->task = iser_task;
	iser_create_send_desc(iser_conn, &iser_task->desc);

	if (hdr->flags & ISCSI_FLAG_CMD_READ)
		data_buf = &iser_task->data[ISER_DIR_IN];
	else
		data_buf = &iser_task->data[ISER_DIR_OUT];

	if (scsi_sg_count(sc)) { /* using a scatter list */
		data_buf->buf  = scsi_sglist(sc);
		data_buf->size = scsi_sg_count(sc);
	}

	data_buf->data_len = scsi_bufflen(sc);

	if (hdr->flags & ISCSI_FLAG_CMD_READ) {
		err = iser_prepare_read_cmd(task, edtl);
		if (err)
			goto send_command_error;
	}
	if (hdr->flags & ISCSI_FLAG_CMD_WRITE) {
		err = iser_prepare_write_cmd(task,
					     task->imm_count,
				             task->imm_count +
					     task->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_task->status = ISER_TASK_STATUS_STARTED;

	err = iser_post_send(&iser_task->desc);
	if (!err)
		return 0;

send_command_error:
	iser_dto_buffs_release(send_dto);
	iser_err("conn %p failed task->itt %d err %d\n",conn, task->itt, err);
	return err;
}

/**
 * iser_send_data_out - send data out PDU
 */
int iser_send_data_out(struct iscsi_conn *conn,
		       struct iscsi_task *task,
		       struct iscsi_data *hdr)
{
	struct iscsi_iser_conn *iser_conn = conn->dd_data;
	struct iscsi_iser_task *iser_task = task->dd_data;
	struct iser_desc *tx_desc = NULL;
	struct iser_dto *send_dto = NULL;
	unsigned long buf_offset;
	unsigned long data_seg_len;
	uint32_t 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, task))
		return -ENOBUFS;

	itt = (__force uint32_t)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->task = iser_task;
	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_task->rdma_regd[ISER_DIR_OUT],
			       buf_offset,
			       data_seg_len);

	if (buf_offset + data_seg_len > iser_task->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_task->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_task *task)
{
	struct iscsi_iser_conn *iser_conn = conn->dd_data;
	struct iscsi_iser_task *iser_task = task->dd_data;
	struct iser_desc *mdesc = &iser_task->desc;
	struct iser_dto *send_dto = NULL;
	unsigned long data_seg_len;
	int err = 0;
	struct iser_regd_buf *regd_buf;
	struct iser_device *device;
	unsigned char opcode;

	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, task))
		return -ENOBUFS;

	/* 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->task = 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);

	data_seg_len = ntoh24(task->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 = task->data;
		regd_buf->data_size = task->data_count;
		iser_reg_single(device, regd_buf,
				DMA_TO_DEVICE);
		iser_dto_add_regd_buff(send_dto, regd_buf,
				       0,
				       data_seg_len);
	}

	opcode = task->hdr->opcode & ISCSI_OPCODE_MASK;

	/* post recv buffer for response if one is expected */
	if (!(opcode == ISCSI_OP_NOOP_OUT && task->hdr->itt == RESERVED_ITT)) {
		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->ib_conn->iser_conn;
	struct iscsi_task *task;
	struct iscsi_iser_task *iser_task;
	struct iscsi_hdr *hdr;
	char   *rx_data = NULL;
	int     rx_data_len = 0;
	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) {
		spin_lock(&conn->iscsi_conn->session->lock);
		task = iscsi_itt_to_ctask(conn->iscsi_conn, hdr->itt);
		if (task)
			__iscsi_get_task(task);
		spin_unlock(&conn->iscsi_conn->session->lock);

		if (!task)
			iser_err("itt can't be matched to task!!! "
				 "conn %p opcode %d itt %d\n",
				 conn->iscsi_conn, opcode, hdr->itt);
		else {
			iser_task = task->dd_data;
			iser_dbg("itt %d task %p\n",hdr->itt, task);
			iser_task->status = ISER_TASK_STATUS_COMPLETED;
			iser_task_rdma_finalize(iser_task);
			iscsi_put_task(task);
		}
	}
	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);

	/*
	 * if an unexpected PDU was received then the recv wr consumed must
	 * be replaced, this is done in the next send of a control-type PDU
	 */
	if (opcode == ISCSI_OP_NOOP_IN && hdr->itt == RESERVED_ITT) {
		/* nop-in with itt = 0xffffffff */
		atomic_inc(&conn->ib_conn->unexpected_pdu_count);
	}
	else if (opcode == ISCSI_OP_ASYNC_EVENT) {
		/* asyncronous message */
		atomic_inc(&conn->ib_conn->unexpected_pdu_count);
	}
	/* a reject PDU consumes the recv buf posted for the response */
}

void iser_snd_completion(struct iser_desc *tx_desc)
{
	struct iser_dto        *dto = &tx_desc->dto;
	struct iser_conn       *ib_conn = dto->ib_conn;
	struct iscsi_iser_conn *iser_conn = ib_conn->iser_conn;
	struct iscsi_conn      *conn = iser_conn->iscsi_conn;
	struct iscsi_task *task;
	int resume_tx = 0;

	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);

	if (atomic_read(&iser_conn->ib_conn->post_send_buf_count) ==
	    ISER_QP_MAX_REQ_DTOS)
		resume_tx = 1;

	atomic_dec(&ib_conn->post_send_buf_count);

	if (resume_tx) {
		iser_dbg("%ld resuming tx\n",jiffies);
		scsi_queue_work(conn->session->host, &conn->xmitwork);
	}

	if (tx_desc->type == ISCSI_TX_CONTROL) {
		/* this arithmetic is legal by libiscsi dd_data allocation */
		task = (void *) ((long)(void *)tx_desc -
				  sizeof(struct iscsi_task));
		if (task->hdr->itt == RESERVED_ITT)
			iscsi_put_task(task);
	}
}

void iser_task_rdma_init(struct iscsi_iser_task *iser_task)

{
	iser_task->status = ISER_TASK_STATUS_INIT;

	iser_task->dir[ISER_DIR_IN] = 0;
	iser_task->dir[ISER_DIR_OUT] = 0;

	iser_task->data[ISER_DIR_IN].data_len  = 0;
	iser_task->data[ISER_DIR_OUT].data_len = 0;

	memset(&iser_task->rdma_regd[ISER_DIR_IN], 0,
	       sizeof(struct iser_regd_buf));
	memset(&iser_task->rdma_regd[ISER_DIR_OUT], 0,
	       sizeof(struct iser_regd_buf));
}

void iser_task_rdma_finalize(struct iscsi_iser_task *iser_task)
{
	int deferred;
	int is_rdma_aligned = 1;
	struct iser_regd_buf *regd;

	/* if we were reading, copy back to unaligned sglist,
	 * anyway dma_unmap and free the copy
	 */
	if (iser_task->data_copy[ISER_DIR_IN].copy_buf != NULL) {
		is_rdma_aligned = 0;
		iser_finalize_rdma_unaligned_sg(iser_task, ISER_DIR_IN);
	}
	if (iser_task->data_copy[ISER_DIR_OUT].copy_buf != NULL) {
		is_rdma_aligned = 0;
		iser_finalize_rdma_unaligned_sg(iser_task, ISER_DIR_OUT);
	}

	if (iser_task->dir[ISER_DIR_IN]) {
		regd = &iser_task->rdma_regd[ISER_DIR_IN];
		deferred = iser_regd_buff_release(regd);
		if (deferred) {
			iser_err("%d references remain for BUF-IN rdma reg\n",
				 atomic_read(&regd->ref_count));
		}
	}

	if (iser_task->dir[ISER_DIR_OUT]) {
		regd = &iser_task->rdma_regd[ISER_DIR_OUT];
		deferred = iser_regd_buff_release(regd);
		if (deferred) {
			iser_err("%d references remain for BUF-OUT rdma reg\n",
				 atomic_read(&regd->ref_count));
		}
	}

       /* if the data was unaligned, it was already unmapped and then copied */
       if (is_rdma_aligned)
		iser_dma_unmap_task_data(iser_task);
}

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]);
}