drivers/target/tcm_fc/tfc_io.c - linux-mtk - Git at Google

 /*
  * Copyright (c) 2010 Cisco Systems, Inc.
  *
  * Portions based on tcm_loop_fabric_scsi.c and libfc/fc_fcp.c
  *
  * Copyright (c) 2007 Intel Corporation. All rights reserved.
  * Copyright (c) 2008 Red Hat, Inc.  All rights reserved.
  * Copyright (c) 2008 Mike Christie
  * Copyright (c) 2009 Rising Tide, Inc.
  * Copyright (c) 2009 Linux-iSCSI.org
  * Copyright (c) 2009 Nicholas A. Bellinger <nab@linux-iscsi.org>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
  * version 2, as published by the Free Software Foundation.
  *
  * This program is distributed in the hope it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  */

 /* XXX TBD some includes may be extraneous */

 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/utsname.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/kthread.h>
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/configfs.h>
 #include <linux/ctype.h>
 #include <linux/hash.h>
 #include <linux/ratelimit.h>
 #include <asm/unaligned.h>
 #include <scsi/libfc.h>
 #include <scsi/fc_encode.h>

 #include <target/target_core_base.h>
 #include <target/target_core_fabric.h>

 #include "tcm_fc.h"

 /*
  * Deliver read data back to initiator.
  * XXX TBD handle resource problems later.
  */
 int ft_queue_data_in(struct se_cmd *se_cmd)
 {
 	struct ft_cmd *cmd = container_of(se_cmd, struct ft_cmd, se_cmd);
 	struct fc_frame *fp = NULL;
 	struct fc_exch *ep;
 	struct fc_lport *lport;
 	struct scatterlist *sg = NULL;
 	size_t remaining;
 	u32 f_ctl = FC_FC_EX_CTX | FC_FC_REL_OFF;
 	u32 mem_off = 0;
 	u32 fh_off = 0;
 	u32 frame_off = 0;
 	size_t frame_len = 0;
 	size_t mem_len = 0;
 	size_t tlen;
 	size_t off_in_page;
 	struct page *page = NULL;
 	int use_sg;
 	int error;
 	void *page_addr;
 	void *from;
 	void *to = NULL;

 	if (cmd->aborted)
 		return 0;

 	if (se_cmd->scsi_status == SAM_STAT_TASK_SET_FULL)
 		goto queue_status;

 	ep = fc_seq_exch(cmd->seq);
 	lport = ep->lp;
 	cmd->seq = fc_seq_start_next(cmd->seq);

 	remaining = se_cmd->data_length;

 	/*
 	 * Setup to use first mem list entry, unless no data.
 	 */
 	BUG_ON(remaining && !se_cmd->t_data_sg);
 	if (remaining) {
 		sg = se_cmd->t_data_sg;
 		mem_len = sg->length;
 		mem_off = sg->offset;
 		page = sg_page(sg);
 	}

 	/* no scatter/gather in skb for odd word length due to fc_seq_send() */
 	use_sg = !(remaining % 4);

 	while (remaining) {
 		struct fc_seq *seq = cmd->seq;

 		if (!seq) {
 			pr_debug("%s: Command aborted, xid 0x%x\n",
 				 __func__, ep->xid);
 			break;
 		}
 		if (!mem_len) {
 			sg = sg_next(sg);
 			mem_len = min((size_t)sg->length, remaining);
 			mem_off = sg->offset;
 			page = sg_page(sg);
 		}
 		if (!frame_len) {
 			/*
 			 * If lport's has capability of Large Send Offload LSO)
 			 * , then allow 'frame_len' to be as big as 'lso_max'
 			 * if indicated transfer length is >= lport->lso_max
 			 */
 			frame_len = (lport->seq_offload) ? lport->lso_max :
 							  cmd->sess->max_frame;
 			frame_len = min(frame_len, remaining);
 			fp = fc_frame_alloc(lport, use_sg ? 0 : frame_len);
 			if (!fp)
 				return -ENOMEM;
 			to = fc_frame_payload_get(fp, 0);
 			fh_off = frame_off;
 			frame_off += frame_len;
 			/*
 			 * Setup the frame's max payload which is used by base
 			 * driver to indicate HW about max frame size, so that
 			 * HW can do fragmentation appropriately based on
 			 * "gso_max_size" of underline netdev.
 			 */
 			fr_max_payload(fp) = cmd->sess->max_frame;
 		}
 		tlen = min(mem_len, frame_len);

 		if (use_sg) {
 			off_in_page = mem_off;
 			BUG_ON(!page);
 			get_page(page);
 			skb_fill_page_desc(fp_skb(fp),
 					   skb_shinfo(fp_skb(fp))->nr_frags,
 					   page, off_in_page, tlen);
 			fr_len(fp) += tlen;
 			fp_skb(fp)->data_len += tlen;
 			fp_skb(fp)->truesize +=
 					PAGE_SIZE << compound_order(page);
 		} else {
 			BUG_ON(!page);
 			from = kmap_atomic(page + (mem_off >> PAGE_SHIFT));
 			page_addr = from;
 			from += offset_in_page(mem_off);
 			tlen = min(tlen, (size_t)(PAGE_SIZE -
 						offset_in_page(mem_off)));
 			memcpy(to, from, tlen);
 			kunmap_atomic(page_addr);
 			to += tlen;
 		}

 		mem_off += tlen;
 		mem_len -= tlen;
 		frame_len -= tlen;
 		remaining -= tlen;

 		if (frame_len &&
 		    (skb_shinfo(fp_skb(fp))->nr_frags < FC_FRAME_SG_LEN))
 			continue;
 		if (!remaining)
 			f_ctl |= FC_FC_END_SEQ;
 		fc_fill_fc_hdr(fp, FC_RCTL_DD_SOL_DATA, ep->did, ep->sid,
 			       FC_TYPE_FCP, f_ctl, fh_off);
 		error = fc_seq_send(lport, seq, fp);
 		if (error) {
 			pr_info_ratelimited("%s: Failed to send frame %p, "
 						"xid <0x%x>, remaining %zu, "
 						"lso_max <0x%x>\n",
 						__func__, fp, ep->xid,
 						remaining, lport->lso_max);
 			/*
 			 * Go ahead and set TASK_SET_FULL status ignoring the
 			 * rest of the DataIN, and immediately attempt to
 			 * send the response via ft_queue_status() in order
 			 * to notify the initiator that it should reduce it's
 			 * per LUN queue_depth.
 			 */
 			se_cmd->scsi_status = SAM_STAT_TASK_SET_FULL;
 			break;
 		}
 	}
 queue_status:
 	return ft_queue_status(se_cmd);
 }

 static void ft_execute_work(struct work_struct *work)
 {
 	struct ft_cmd *cmd = container_of(work, struct ft_cmd, work);

 	target_execute_cmd(&cmd->se_cmd);
 }

 /*
  * Receive write data frame.
  */
 void ft_recv_write_data(struct ft_cmd *cmd, struct fc_frame *fp)
 {
 	struct se_cmd *se_cmd = &cmd->se_cmd;
 	struct fc_seq *seq = cmd->seq;
 	struct fc_exch *ep;
 	struct fc_lport *lport;
 	struct fc_frame_header *fh;
 	struct scatterlist *sg = NULL;
 	u32 mem_off = 0;
 	u32 rel_off;
 	size_t frame_len;
 	size_t mem_len = 0;
 	size_t tlen;
 	struct page *page = NULL;
 	void *page_addr;
 	void *from;
 	void *to;
 	u32 f_ctl;
 	void *buf;

 	fh = fc_frame_header_get(fp);
 	if (!(ntoh24(fh->fh_f_ctl) & FC_FC_REL_OFF))
 		goto drop;

 	f_ctl = ntoh24(fh->fh_f_ctl);
 	ep = fc_seq_exch(seq);
 	lport = ep->lp;
 	if (cmd->was_ddp_setup) {
 		BUG_ON(!ep);
 		BUG_ON(!lport);
 		/*
 		 * Since DDP (Large Rx offload) was setup for this request,
 		 * payload is expected to be copied directly to user buffers.
 		 */
 		buf = fc_frame_payload_get(fp, 1);
 		if (buf)
 			pr_err("%s: xid 0x%x, f_ctl 0x%x, cmd->sg %p, "
 				"cmd->sg_cnt 0x%x. DDP was setup"
 				" hence not expected to receive frame with "
 				"payload, Frame will be dropped if"
 				"'Sequence Initiative' bit in f_ctl is"
 				"not set\n", __func__, ep->xid, f_ctl,
 				se_cmd->t_data_sg, se_cmd->t_data_nents);
 		/*
 		 * Invalidate HW DDP context if it was setup for respective
 		 * command. Invalidation of HW DDP context is requited in both
 		 * situation (success and error).
 		 */
 		ft_invl_hw_context(cmd);

 		/*
 		 * If "Sequence Initiative (TSI)" bit set in f_ctl, means last
 		 * write data frame is received successfully where payload is
 		 * posted directly to user buffer and only the last frame's
 		 * header is posted in receive queue.
 		 *
 		 * If "Sequence Initiative (TSI)" bit is not set, means error
 		 * condition w.r.t. DDP, hence drop the packet and let explict
 		 * ABORTS from other end of exchange timer trigger the recovery.
 		 */
 		if (f_ctl & FC_FC_SEQ_INIT)
 			goto last_frame;
 		else
 			goto drop;
 	}

 	rel_off = ntohl(fh->fh_parm_offset);
 	frame_len = fr_len(fp);
 	if (frame_len <= sizeof(*fh))
 		goto drop;
 	frame_len -= sizeof(*fh);
 	from = fc_frame_payload_get(fp, 0);
 	if (rel_off >= se_cmd->data_length)
 		goto drop;
 	if (frame_len + rel_off > se_cmd->data_length)
 		frame_len = se_cmd->data_length - rel_off;

 	/*
 	 * Setup to use first mem list entry, unless no data.
 	 */
 	BUG_ON(frame_len && !se_cmd->t_data_sg);
 	if (frame_len) {
 		sg = se_cmd->t_data_sg;
 		mem_len = sg->length;
 		mem_off = sg->offset;
 		page = sg_page(sg);
 	}

 	while (frame_len) {
 		if (!mem_len) {
 			sg = sg_next(sg);
 			mem_len = sg->length;
 			mem_off = sg->offset;
 			page = sg_page(sg);
 		}
 		if (rel_off >= mem_len) {
 			rel_off -= mem_len;
 			mem_len = 0;
 			continue;
 		}
 		mem_off += rel_off;
 		mem_len -= rel_off;
 		rel_off = 0;

 		tlen = min(mem_len, frame_len);

 		to = kmap_atomic(page + (mem_off >> PAGE_SHIFT));
 		page_addr = to;
 		to += offset_in_page(mem_off);
 		tlen = min(tlen, (size_t)(PAGE_SIZE -
 					  offset_in_page(mem_off)));
 		memcpy(to, from, tlen);
 		kunmap_atomic(page_addr);

 		from += tlen;
 		frame_len -= tlen;
 		mem_off += tlen;
 		mem_len -= tlen;
 		cmd->write_data_len += tlen;
 	}
 last_frame:
 	if (cmd->write_data_len == se_cmd->data_length) {
 		INIT_WORK(&cmd->work, ft_execute_work);
 		queue_work(cmd->sess->tport->tpg->workqueue, &cmd->work);
 	}
 drop:
 	fc_frame_free(fp);
 }

 /*
  * Handle and cleanup any HW specific resources if
  * received ABORTS, errors, timeouts.
  */
 void ft_invl_hw_context(struct ft_cmd *cmd)
 {
 	struct fc_seq *seq;
 	struct fc_exch *ep = NULL;
 	struct fc_lport *lport = NULL;

 	BUG_ON(!cmd);
 	seq = cmd->seq;

 	/* Cleanup the DDP context in HW if DDP was setup */
 	if (cmd->was_ddp_setup && seq) {
 		ep = fc_seq_exch(seq);
 		if (ep) {
 			lport = ep->lp;
 			if (lport && (ep->xid <= lport->lro_xid)) {
 				/*
 				 * "ddp_done" trigger invalidation of HW
 				 * specific DDP context
 				 */
 				cmd->write_data_len = lport->tt.ddp_done(lport,
 								      ep->xid);

 				/*
 				 * Resetting same variable to indicate HW's
 				 * DDP context has been invalidated to avoid
 				 * re_invalidation of same context (context is
 				 * identified using ep->xid)
 				 */
 				cmd->was_ddp_setup = 0;
 			}
 		}
 	}
 }
	/*
	* Copyright (c) 2010 Cisco Systems, Inc.
	*
	* Portions based on tcm_loop_fabric_scsi.c and libfc/fc_fcp.c
	*
	* Copyright (c) 2007 Intel Corporation. All rights reserved.
	* Copyright (c) 2008 Red Hat, Inc. All rights reserved.
	* Copyright (c) 2008 Mike Christie
	* Copyright (c) 2009 Rising Tide, Inc.
	* Copyright (c) 2009 Linux-iSCSI.org
	* Copyright (c) 2009 Nicholas A. Bellinger <nab@linux-iscsi.org>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms and conditions of the GNU General Public License,
	* version 2, as published by the Free Software Foundation.
	*
	* This program is distributed in the hope it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* this program; if not, write to the Free Software Foundation, Inc.,
	* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
	*/

	/* XXX TBD some includes may be extraneous */

	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/utsname.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/kthread.h>
	#include <linux/types.h>
	#include <linux/string.h>
	#include <linux/configfs.h>
	#include <linux/ctype.h>
	#include <linux/hash.h>
	#include <linux/ratelimit.h>
	#include <asm/unaligned.h>
	#include <scsi/libfc.h>
	#include <scsi/fc_encode.h>

	#include <target/target_core_base.h>
	#include <target/target_core_fabric.h>

	#include "tcm_fc.h"

	/*
	* Deliver read data back to initiator.
	* XXX TBD handle resource problems later.
	*/
	int ft_queue_data_in(struct se_cmd *se_cmd)
	{
	struct ft_cmd *cmd = container_of(se_cmd, struct ft_cmd, se_cmd);
	struct fc_frame *fp = NULL;
	struct fc_exch *ep;
	struct fc_lport *lport;
	struct scatterlist *sg = NULL;
	size_t remaining;
	u32 f_ctl = FC_FC_EX_CTX \| FC_FC_REL_OFF;
	u32 mem_off = 0;
	u32 fh_off = 0;
	u32 frame_off = 0;
	size_t frame_len = 0;
	size_t mem_len = 0;
	size_t tlen;
	size_t off_in_page;
	struct page *page = NULL;
	int use_sg;
	int error;
	void *page_addr;
	void *from;
	void *to = NULL;

	if (cmd->aborted)
	return 0;

	if (se_cmd->scsi_status == SAM_STAT_TASK_SET_FULL)
	goto queue_status;

	ep = fc_seq_exch(cmd->seq);
	lport = ep->lp;
	cmd->seq = fc_seq_start_next(cmd->seq);

	remaining = se_cmd->data_length;

	/*
	* Setup to use first mem list entry, unless no data.
	*/
	BUG_ON(remaining && !se_cmd->t_data_sg);
	if (remaining) {
	sg = se_cmd->t_data_sg;
	mem_len = sg->length;
	mem_off = sg->offset;
	page = sg_page(sg);
	}

	/* no scatter/gather in skb for odd word length due to fc_seq_send() */
	use_sg = !(remaining % 4);

	while (remaining) {
	struct fc_seq *seq = cmd->seq;

	if (!seq) {
	pr_debug("%s: Command aborted, xid 0x%x\n",
	__func__, ep->xid);
	break;
	}
	if (!mem_len) {
	sg = sg_next(sg);
	mem_len = min((size_t)sg->length, remaining);
	mem_off = sg->offset;
	page = sg_page(sg);
	}
	if (!frame_len) {
	/*
	* If lport's has capability of Large Send Offload LSO)
	* , then allow 'frame_len' to be as big as 'lso_max'
	* if indicated transfer length is >= lport->lso_max
	*/
	frame_len = (lport->seq_offload) ? lport->lso_max :
	cmd->sess->max_frame;
	frame_len = min(frame_len, remaining);
	fp = fc_frame_alloc(lport, use_sg ? 0 : frame_len);
	if (!fp)
	return -ENOMEM;
	to = fc_frame_payload_get(fp, 0);
	fh_off = frame_off;
	frame_off += frame_len;
	/*
	* Setup the frame's max payload which is used by base
	* driver to indicate HW about max frame size, so that
	* HW can do fragmentation appropriately based on
	* "gso_max_size" of underline netdev.
	*/
	fr_max_payload(fp) = cmd->sess->max_frame;
	}
	tlen = min(mem_len, frame_len);

	if (use_sg) {
	off_in_page = mem_off;
	BUG_ON(!page);
	get_page(page);
	skb_fill_page_desc(fp_skb(fp),
	skb_shinfo(fp_skb(fp))->nr_frags,
	page, off_in_page, tlen);
	fr_len(fp) += tlen;
	fp_skb(fp)->data_len += tlen;
	fp_skb(fp)->truesize +=
	PAGE_SIZE << compound_order(page);
	} else {
	BUG_ON(!page);
	from = kmap_atomic(page + (mem_off >> PAGE_SHIFT));
	page_addr = from;
	from += offset_in_page(mem_off);
	tlen = min(tlen, (size_t)(PAGE_SIZE -
	offset_in_page(mem_off)));
	memcpy(to, from, tlen);
	kunmap_atomic(page_addr);
	to += tlen;
	}

	mem_off += tlen;
	mem_len -= tlen;
	frame_len -= tlen;
	remaining -= tlen;

	if (frame_len &&
	(skb_shinfo(fp_skb(fp))->nr_frags < FC_FRAME_SG_LEN))
	continue;
	if (!remaining)
	f_ctl \|= FC_FC_END_SEQ;
	fc_fill_fc_hdr(fp, FC_RCTL_DD_SOL_DATA, ep->did, ep->sid,
	FC_TYPE_FCP, f_ctl, fh_off);
	error = fc_seq_send(lport, seq, fp);
	if (error) {
	pr_info_ratelimited("%s: Failed to send frame %p, "
	"xid <0x%x>, remaining %zu, "
	"lso_max <0x%x>\n",
	__func__, fp, ep->xid,
	remaining, lport->lso_max);
	/*
	* Go ahead and set TASK_SET_FULL status ignoring the
	* rest of the DataIN, and immediately attempt to
	* send the response via ft_queue_status() in order
	* to notify the initiator that it should reduce it's
	* per LUN queue_depth.
	*/
	se_cmd->scsi_status = SAM_STAT_TASK_SET_FULL;
	break;
	}
	}
	queue_status:
	return ft_queue_status(se_cmd);
	}

	static void ft_execute_work(struct work_struct *work)
	{
	struct ft_cmd *cmd = container_of(work, struct ft_cmd, work);

	target_execute_cmd(&cmd->se_cmd);
	}

	/*
	* Receive write data frame.
	*/
	void ft_recv_write_data(struct ft_cmd cmd, struct fc_frame fp)
	{
	struct se_cmd *se_cmd = &cmd->se_cmd;
	struct fc_seq *seq = cmd->seq;
	struct fc_exch *ep;
	struct fc_lport *lport;
	struct fc_frame_header *fh;
	struct scatterlist *sg = NULL;
	u32 mem_off = 0;
	u32 rel_off;
	size_t frame_len;
	size_t mem_len = 0;
	size_t tlen;
	struct page *page = NULL;
	void *page_addr;
	void *from;
	void *to;
	u32 f_ctl;
	void *buf;

	fh = fc_frame_header_get(fp);
	if (!(ntoh24(fh->fh_f_ctl) & FC_FC_REL_OFF))
	goto drop;

	f_ctl = ntoh24(fh->fh_f_ctl);
	ep = fc_seq_exch(seq);
	lport = ep->lp;
	if (cmd->was_ddp_setup) {
	BUG_ON(!ep);
	BUG_ON(!lport);
	/*
	* Since DDP (Large Rx offload) was setup for this request,
	* payload is expected to be copied directly to user buffers.
	*/
	buf = fc_frame_payload_get(fp, 1);
	if (buf)
	pr_err("%s: xid 0x%x, f_ctl 0x%x, cmd->sg %p, "
	"cmd->sg_cnt 0x%x. DDP was setup"
	" hence not expected to receive frame with "
	"payload, Frame will be dropped if"
	"'Sequence Initiative' bit in f_ctl is"
	"not set\n", __func__, ep->xid, f_ctl,
	se_cmd->t_data_sg, se_cmd->t_data_nents);
	/*
	* Invalidate HW DDP context if it was setup for respective
	* command. Invalidation of HW DDP context is requited in both
	* situation (success and error).
	*/
	ft_invl_hw_context(cmd);

	/*
	* If "Sequence Initiative (TSI)" bit set in f_ctl, means last
	* write data frame is received successfully where payload is
	* posted directly to user buffer and only the last frame's
	* header is posted in receive queue.
	*
	* If "Sequence Initiative (TSI)" bit is not set, means error
	* condition w.r.t. DDP, hence drop the packet and let explict
	* ABORTS from other end of exchange timer trigger the recovery.
	*/
	if (f_ctl & FC_FC_SEQ_INIT)
	goto last_frame;
	else
	goto drop;
	}

	rel_off = ntohl(fh->fh_parm_offset);
	frame_len = fr_len(fp);
	if (frame_len <= sizeof(*fh))
	goto drop;
	frame_len -= sizeof(*fh);
	from = fc_frame_payload_get(fp, 0);
	if (rel_off >= se_cmd->data_length)
	goto drop;
	if (frame_len + rel_off > se_cmd->data_length)
	frame_len = se_cmd->data_length - rel_off;

	/*
	* Setup to use first mem list entry, unless no data.
	*/
	BUG_ON(frame_len && !se_cmd->t_data_sg);
	if (frame_len) {
	sg = se_cmd->t_data_sg;
	mem_len = sg->length;
	mem_off = sg->offset;
	page = sg_page(sg);
	}

	while (frame_len) {
	if (!mem_len) {
	sg = sg_next(sg);
	mem_len = sg->length;
	mem_off = sg->offset;
	page = sg_page(sg);
	}
	if (rel_off >= mem_len) {
	rel_off -= mem_len;
	mem_len = 0;
	continue;
	}
	mem_off += rel_off;
	mem_len -= rel_off;
	rel_off = 0;

	tlen = min(mem_len, frame_len);

	to = kmap_atomic(page + (mem_off >> PAGE_SHIFT));
	page_addr = to;
	to += offset_in_page(mem_off);
	tlen = min(tlen, (size_t)(PAGE_SIZE -
	offset_in_page(mem_off)));
	memcpy(to, from, tlen);
	kunmap_atomic(page_addr);

	from += tlen;
	frame_len -= tlen;
	mem_off += tlen;
	mem_len -= tlen;
	cmd->write_data_len += tlen;
	}
	last_frame:
	if (cmd->write_data_len == se_cmd->data_length) {
	INIT_WORK(&cmd->work, ft_execute_work);
	queue_work(cmd->sess->tport->tpg->workqueue, &cmd->work);
	}
	drop:
	fc_frame_free(fp);
	}

	/*
	* Handle and cleanup any HW specific resources if
	* received ABORTS, errors, timeouts.
	*/
	void ft_invl_hw_context(struct ft_cmd *cmd)
	{
	struct fc_seq *seq;
	struct fc_exch *ep = NULL;
	struct fc_lport *lport = NULL;

	BUG_ON(!cmd);
	seq = cmd->seq;

	/* Cleanup the DDP context in HW if DDP was setup */
	if (cmd->was_ddp_setup && seq) {
	ep = fc_seq_exch(seq);
	if (ep) {
	lport = ep->lp;
	if (lport && (ep->xid <= lport->lro_xid)) {
	/*
	* "ddp_done" trigger invalidation of HW
	* specific DDP context
	*/
	cmd->write_data_len = lport->tt.ddp_done(lport,
	ep->xid);

	/*
	* Resetting same variable to indicate HW's
	* DDP context has been invalidated to avoid
	* re_invalidation of same context (context is
	* identified using ep->xid)
	*/
	cmd->was_ddp_setup = 0;
	}
	}
	}
	}