drivers/infiniband/hw/mlx4/srq.c - arm/linux-arm64-legacy - Git at Google

 /*
  * Copyright (c) 2007 Cisco Systems, Inc. All rights reserved.
  * Copyright (c) 2007, 2008 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/mlx4/qp.h>
 #include <linux/mlx4/srq.h>
 #include <linux/slab.h>

 #include "mlx4_ib.h"
 #include "user.h"

 static void *get_wqe(struct mlx4_ib_srq *srq, int n)
 {
 	return mlx4_buf_offset(&srq->buf, n << srq->msrq.wqe_shift);
 }

 static void mlx4_ib_srq_event(struct mlx4_srq *srq, enum mlx4_event type)
 {
 	struct ib_event event;
 	struct ib_srq *ibsrq = &to_mibsrq(srq)->ibsrq;

 	if (ibsrq->event_handler) {
 		event.device      = ibsrq->device;
 		event.element.srq = ibsrq;
 		switch (type) {
 		case MLX4_EVENT_TYPE_SRQ_LIMIT:
 			event.event = IB_EVENT_SRQ_LIMIT_REACHED;
 			break;
 		case MLX4_EVENT_TYPE_SRQ_CATAS_ERROR:
 			event.event = IB_EVENT_SRQ_ERR;
 			break;
 		default:
 			printk(KERN_WARNING "mlx4_ib: Unexpected event type %d "
 			       "on SRQ %06x\n", type, srq->srqn);
 			return;
 		}

 		ibsrq->event_handler(&event, ibsrq->srq_context);
 	}
 }

 struct ib_srq *mlx4_ib_create_srq(struct ib_pd *pd,
 				  struct ib_srq_init_attr *init_attr,
 				  struct ib_udata *udata)
 {
 	struct mlx4_ib_dev *dev = to_mdev(pd->device);
 	struct mlx4_ib_srq *srq;
 	struct mlx4_wqe_srq_next_seg *next;
 	struct mlx4_wqe_data_seg *scatter;
 	int desc_size;
 	int buf_size;
 	int err;
 	int i;

 	/* Sanity check SRQ size before proceeding */
 	if (init_attr->attr.max_wr  >= dev->dev->caps.max_srq_wqes ||
 	    init_attr->attr.max_sge >  dev->dev->caps.max_srq_sge)
 		return ERR_PTR(-EINVAL);

 	srq = kmalloc(sizeof *srq, GFP_KERNEL);
 	if (!srq)
 		return ERR_PTR(-ENOMEM);

 	mutex_init(&srq->mutex);
 	spin_lock_init(&srq->lock);
 	srq->msrq.max    = roundup_pow_of_two(init_attr->attr.max_wr + 1);
 	srq->msrq.max_gs = init_attr->attr.max_sge;

 	desc_size = max(32UL,
 			roundup_pow_of_two(sizeof (struct mlx4_wqe_srq_next_seg) +
 					   srq->msrq.max_gs *
 					   sizeof (struct mlx4_wqe_data_seg)));
 	srq->msrq.wqe_shift = ilog2(desc_size);

 	buf_size = srq->msrq.max * desc_size;

 	if (pd->uobject) {
 		struct mlx4_ib_create_srq ucmd;

 		if (ib_copy_from_udata(&ucmd, udata, sizeof ucmd)) {
 			err = -EFAULT;
 			goto err_srq;
 		}

 		srq->umem = ib_umem_get(pd->uobject->context, ucmd.buf_addr,
 					buf_size, 0, 0);
 		if (IS_ERR(srq->umem)) {
 			err = PTR_ERR(srq->umem);
 			goto err_srq;
 		}

 		err = mlx4_mtt_init(dev->dev, ib_umem_page_count(srq->umem),
 				    ilog2(srq->umem->page_size), &srq->mtt);
 		if (err)
 			goto err_buf;

 		err = mlx4_ib_umem_write_mtt(dev, &srq->mtt, srq->umem);
 		if (err)
 			goto err_mtt;

 		err = mlx4_ib_db_map_user(to_mucontext(pd->uobject->context),
 					  ucmd.db_addr, &srq->db);
 		if (err)
 			goto err_mtt;
 	} else {
 		err = mlx4_db_alloc(dev->dev, &srq->db, 0);
 		if (err)
 			goto err_srq;

 		*srq->db.db = 0;

 		if (mlx4_buf_alloc(dev->dev, buf_size, PAGE_SIZE * 2, &srq->buf)) {
 			err = -ENOMEM;
 			goto err_db;
 		}

 		srq->head    = 0;
 		srq->tail    = srq->msrq.max - 1;
 		srq->wqe_ctr = 0;

 		for (i = 0; i < srq->msrq.max; ++i) {
 			next = get_wqe(srq, i);
 			next->next_wqe_index =
 				cpu_to_be16((i + 1) & (srq->msrq.max - 1));

 			for (scatter = (void *) (next + 1);
 			     (void *) scatter < (void *) next + desc_size;
 			     ++scatter)
 				scatter->lkey = cpu_to_be32(MLX4_INVALID_LKEY);
 		}

 		err = mlx4_mtt_init(dev->dev, srq->buf.npages, srq->buf.page_shift,
 				    &srq->mtt);
 		if (err)
 			goto err_buf;

 		err = mlx4_buf_write_mtt(dev->dev, &srq->mtt, &srq->buf);
 		if (err)
 			goto err_mtt;

 		srq->wrid = kmalloc(srq->msrq.max * sizeof (u64), GFP_KERNEL);
 		if (!srq->wrid) {
 			err = -ENOMEM;
 			goto err_mtt;
 		}
 	}

 	err = mlx4_srq_alloc(dev->dev, to_mpd(pd)->pdn, &srq->mtt,
 			     srq->db.dma, &srq->msrq);
 	if (err)
 		goto err_wrid;

 	srq->msrq.event = mlx4_ib_srq_event;

 	if (pd->uobject)
 		if (ib_copy_to_udata(udata, &srq->msrq.srqn, sizeof (__u32))) {
 			err = -EFAULT;
 			goto err_wrid;
 		}

 	init_attr->attr.max_wr = srq->msrq.max - 1;

 	return &srq->ibsrq;

 err_wrid:
 	if (pd->uobject)
 		mlx4_ib_db_unmap_user(to_mucontext(pd->uobject->context), &srq->db);
 	else
 		kfree(srq->wrid);

 err_mtt:
 	mlx4_mtt_cleanup(dev->dev, &srq->mtt);

 err_buf:
 	if (pd->uobject)
 		ib_umem_release(srq->umem);
 	else
 		mlx4_buf_free(dev->dev, buf_size, &srq->buf);

 err_db:
 	if (!pd->uobject)
 		mlx4_db_free(dev->dev, &srq->db);

 err_srq:
 	kfree(srq);

 	return ERR_PTR(err);
 }

 int mlx4_ib_modify_srq(struct ib_srq *ibsrq, struct ib_srq_attr *attr,
 		       enum ib_srq_attr_mask attr_mask, struct ib_udata *udata)
 {
 	struct mlx4_ib_dev *dev = to_mdev(ibsrq->device);
 	struct mlx4_ib_srq *srq = to_msrq(ibsrq);
 	int ret;

 	/* We don't support resizing SRQs (yet?) */
 	if (attr_mask & IB_SRQ_MAX_WR)
 		return -EINVAL;

 	if (attr_mask & IB_SRQ_LIMIT) {
 		if (attr->srq_limit >= srq->msrq.max)
 			return -EINVAL;

 		mutex_lock(&srq->mutex);
 		ret = mlx4_srq_arm(dev->dev, &srq->msrq, attr->srq_limit);
 		mutex_unlock(&srq->mutex);

 		if (ret)
 			return ret;
 	}

 	return 0;
 }

 int mlx4_ib_query_srq(struct ib_srq *ibsrq, struct ib_srq_attr *srq_attr)
 {
 	struct mlx4_ib_dev *dev = to_mdev(ibsrq->device);
 	struct mlx4_ib_srq *srq = to_msrq(ibsrq);
 	int ret;
 	int limit_watermark;

 	ret = mlx4_srq_query(dev->dev, &srq->msrq, &limit_watermark);
 	if (ret)
 		return ret;

 	srq_attr->srq_limit = limit_watermark;
 	srq_attr->max_wr    = srq->msrq.max - 1;
 	srq_attr->max_sge   = srq->msrq.max_gs;

 	return 0;
 }

 int mlx4_ib_destroy_srq(struct ib_srq *srq)
 {
 	struct mlx4_ib_dev *dev = to_mdev(srq->device);
 	struct mlx4_ib_srq *msrq = to_msrq(srq);

 	mlx4_srq_free(dev->dev, &msrq->msrq);
 	mlx4_mtt_cleanup(dev->dev, &msrq->mtt);

 	if (srq->uobject) {
 		mlx4_ib_db_unmap_user(to_mucontext(srq->uobject->context), &msrq->db);
 		ib_umem_release(msrq->umem);
 	} else {
 		kfree(msrq->wrid);
 		mlx4_buf_free(dev->dev, msrq->msrq.max << msrq->msrq.wqe_shift,
 			      &msrq->buf);
 		mlx4_db_free(dev->dev, &msrq->db);
 	}

 	kfree(msrq);

 	return 0;
 }

 void mlx4_ib_free_srq_wqe(struct mlx4_ib_srq *srq, int wqe_index)
 {
 	struct mlx4_wqe_srq_next_seg *next;

 	/* always called with interrupts disabled. */
 	spin_lock(&srq->lock);

 	next = get_wqe(srq, srq->tail);
 	next->next_wqe_index = cpu_to_be16(wqe_index);
 	srq->tail = wqe_index;

 	spin_unlock(&srq->lock);
 }

 int mlx4_ib_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
 			  struct ib_recv_wr **bad_wr)
 {
 	struct mlx4_ib_srq *srq = to_msrq(ibsrq);
 	struct mlx4_wqe_srq_next_seg *next;
 	struct mlx4_wqe_data_seg *scat;
 	unsigned long flags;
 	int err = 0;
 	int nreq;
 	int i;

 	spin_lock_irqsave(&srq->lock, flags);

 	for (nreq = 0; wr; ++nreq, wr = wr->next) {
 		if (unlikely(wr->num_sge > srq->msrq.max_gs)) {
 			err = -EINVAL;
 			*bad_wr = wr;
 			break;
 		}

 		if (unlikely(srq->head == srq->tail)) {
 			err = -ENOMEM;
 			*bad_wr = wr;
 			break;
 		}

 		srq->wrid[srq->head] = wr->wr_id;

 		next      = get_wqe(srq, srq->head);
 		srq->head = be16_to_cpu(next->next_wqe_index);
 		scat      = (struct mlx4_wqe_data_seg *) (next + 1);

 		for (i = 0; i < wr->num_sge; ++i) {
 			scat[i].byte_count = cpu_to_be32(wr->sg_list[i].length);
 			scat[i].lkey       = cpu_to_be32(wr->sg_list[i].lkey);
 			scat[i].addr       = cpu_to_be64(wr->sg_list[i].addr);
 		}

 		if (i < srq->msrq.max_gs) {
 			scat[i].byte_count = 0;
 			scat[i].lkey       = cpu_to_be32(MLX4_INVALID_LKEY);
 			scat[i].addr       = 0;
 		}
 	}

 	if (likely(nreq)) {
 		srq->wqe_ctr += nreq;

 		/*
 		 * Make sure that descriptors are written before
 		 * doorbell record.
 		 */
 		wmb();

 		*srq->db.db = cpu_to_be32(srq->wqe_ctr);
 	}

 	spin_unlock_irqrestore(&srq->lock, flags);

 	return err;
 }
	/*
	* Copyright (c) 2007 Cisco Systems, Inc. All rights reserved.
	* Copyright (c) 2007, 2008 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/mlx4/qp.h>
	#include <linux/mlx4/srq.h>
	#include <linux/slab.h>

	#include "mlx4_ib.h"
	#include "user.h"

	static void get_wqe(struct mlx4_ib_srq srq, int n)
	{
	return mlx4_buf_offset(&srq->buf, n << srq->msrq.wqe_shift);
	}

	static void mlx4_ib_srq_event(struct mlx4_srq *srq, enum mlx4_event type)
	{
	struct ib_event event;
	struct ib_srq *ibsrq = &to_mibsrq(srq)->ibsrq;

	if (ibsrq->event_handler) {
	event.device = ibsrq->device;
	event.element.srq = ibsrq;
	switch (type) {
	case MLX4_EVENT_TYPE_SRQ_LIMIT:
	event.event = IB_EVENT_SRQ_LIMIT_REACHED;
	break;
	case MLX4_EVENT_TYPE_SRQ_CATAS_ERROR:
	event.event = IB_EVENT_SRQ_ERR;
	break;
	default:
	printk(KERN_WARNING "mlx4_ib: Unexpected event type %d "
	"on SRQ %06x\n", type, srq->srqn);
	return;
	}

	ibsrq->event_handler(&event, ibsrq->srq_context);
	}
	}

	struct ib_srq mlx4_ib_create_srq(struct ib_pd pd,
	struct ib_srq_init_attr *init_attr,
	struct ib_udata *udata)
	{
	struct mlx4_ib_dev *dev = to_mdev(pd->device);
	struct mlx4_ib_srq *srq;
	struct mlx4_wqe_srq_next_seg *next;
	struct mlx4_wqe_data_seg *scatter;
	int desc_size;
	int buf_size;
	int err;
	int i;

	/* Sanity check SRQ size before proceeding */
	if (init_attr->attr.max_wr >= dev->dev->caps.max_srq_wqes \|\|
	init_attr->attr.max_sge > dev->dev->caps.max_srq_sge)
	return ERR_PTR(-EINVAL);

	srq = kmalloc(sizeof *srq, GFP_KERNEL);
	if (!srq)
	return ERR_PTR(-ENOMEM);

	mutex_init(&srq->mutex);
	spin_lock_init(&srq->lock);
	srq->msrq.max = roundup_pow_of_two(init_attr->attr.max_wr + 1);
	srq->msrq.max_gs = init_attr->attr.max_sge;

	desc_size = max(32UL,
	roundup_pow_of_two(sizeof (struct mlx4_wqe_srq_next_seg) +
	srq->msrq.max_gs *
	sizeof (struct mlx4_wqe_data_seg)));
	srq->msrq.wqe_shift = ilog2(desc_size);

	buf_size = srq->msrq.max * desc_size;

	if (pd->uobject) {
	struct mlx4_ib_create_srq ucmd;

	if (ib_copy_from_udata(&ucmd, udata, sizeof ucmd)) {
	err = -EFAULT;
	goto err_srq;
	}

	srq->umem = ib_umem_get(pd->uobject->context, ucmd.buf_addr,
	buf_size, 0, 0);
	if (IS_ERR(srq->umem)) {
	err = PTR_ERR(srq->umem);
	goto err_srq;
	}

	err = mlx4_mtt_init(dev->dev, ib_umem_page_count(srq->umem),
	ilog2(srq->umem->page_size), &srq->mtt);
	if (err)
	goto err_buf;

	err = mlx4_ib_umem_write_mtt(dev, &srq->mtt, srq->umem);
	if (err)
	goto err_mtt;

	err = mlx4_ib_db_map_user(to_mucontext(pd->uobject->context),
	ucmd.db_addr, &srq->db);
	if (err)
	goto err_mtt;
	} else {
	err = mlx4_db_alloc(dev->dev, &srq->db, 0);
	if (err)
	goto err_srq;

	*srq->db.db = 0;

	if (mlx4_buf_alloc(dev->dev, buf_size, PAGE_SIZE * 2, &srq->buf)) {
	err = -ENOMEM;
	goto err_db;
	}

	srq->head = 0;
	srq->tail = srq->msrq.max - 1;
	srq->wqe_ctr = 0;

	for (i = 0; i < srq->msrq.max; ++i) {
	next = get_wqe(srq, i);
	next->next_wqe_index =
	cpu_to_be16((i + 1) & (srq->msrq.max - 1));

	for (scatter = (void *) (next + 1);
	(void ) scatter < (void ) next + desc_size;
	++scatter)
	scatter->lkey = cpu_to_be32(MLX4_INVALID_LKEY);
	}

	err = mlx4_mtt_init(dev->dev, srq->buf.npages, srq->buf.page_shift,
	&srq->mtt);
	if (err)
	goto err_buf;

	err = mlx4_buf_write_mtt(dev->dev, &srq->mtt, &srq->buf);
	if (err)
	goto err_mtt;

	srq->wrid = kmalloc(srq->msrq.max * sizeof (u64), GFP_KERNEL);
	if (!srq->wrid) {
	err = -ENOMEM;
	goto err_mtt;
	}
	}

	err = mlx4_srq_alloc(dev->dev, to_mpd(pd)->pdn, &srq->mtt,
	srq->db.dma, &srq->msrq);
	if (err)
	goto err_wrid;

	srq->msrq.event = mlx4_ib_srq_event;

	if (pd->uobject)
	if (ib_copy_to_udata(udata, &srq->msrq.srqn, sizeof (__u32))) {
	err = -EFAULT;
	goto err_wrid;
	}

	init_attr->attr.max_wr = srq->msrq.max - 1;

	return &srq->ibsrq;

	err_wrid:
	if (pd->uobject)
	mlx4_ib_db_unmap_user(to_mucontext(pd->uobject->context), &srq->db);
	else
	kfree(srq->wrid);

	err_mtt:
	mlx4_mtt_cleanup(dev->dev, &srq->mtt);

	err_buf:
	if (pd->uobject)
	ib_umem_release(srq->umem);
	else
	mlx4_buf_free(dev->dev, buf_size, &srq->buf);

	err_db:
	if (!pd->uobject)
	mlx4_db_free(dev->dev, &srq->db);

	err_srq:
	kfree(srq);

	return ERR_PTR(err);
	}

	int mlx4_ib_modify_srq(struct ib_srq ibsrq, struct ib_srq_attr attr,
	enum ib_srq_attr_mask attr_mask, struct ib_udata *udata)
	{
	struct mlx4_ib_dev *dev = to_mdev(ibsrq->device);
	struct mlx4_ib_srq *srq = to_msrq(ibsrq);
	int ret;

	/* We don't support resizing SRQs (yet?) */
	if (attr_mask & IB_SRQ_MAX_WR)
	return -EINVAL;

	if (attr_mask & IB_SRQ_LIMIT) {
	if (attr->srq_limit >= srq->msrq.max)
	return -EINVAL;

	mutex_lock(&srq->mutex);
	ret = mlx4_srq_arm(dev->dev, &srq->msrq, attr->srq_limit);
	mutex_unlock(&srq->mutex);

	if (ret)
	return ret;
	}

	return 0;
	}

	int mlx4_ib_query_srq(struct ib_srq ibsrq, struct ib_srq_attr srq_attr)
	{
	struct mlx4_ib_dev *dev = to_mdev(ibsrq->device);
	struct mlx4_ib_srq *srq = to_msrq(ibsrq);
	int ret;
	int limit_watermark;

	ret = mlx4_srq_query(dev->dev, &srq->msrq, &limit_watermark);
	if (ret)
	return ret;

	srq_attr->srq_limit = limit_watermark;
	srq_attr->max_wr = srq->msrq.max - 1;
	srq_attr->max_sge = srq->msrq.max_gs;

	return 0;
	}

	int mlx4_ib_destroy_srq(struct ib_srq *srq)
	{
	struct mlx4_ib_dev *dev = to_mdev(srq->device);
	struct mlx4_ib_srq *msrq = to_msrq(srq);

	mlx4_srq_free(dev->dev, &msrq->msrq);
	mlx4_mtt_cleanup(dev->dev, &msrq->mtt);

	if (srq->uobject) {
	mlx4_ib_db_unmap_user(to_mucontext(srq->uobject->context), &msrq->db);
	ib_umem_release(msrq->umem);
	} else {
	kfree(msrq->wrid);
	mlx4_buf_free(dev->dev, msrq->msrq.max << msrq->msrq.wqe_shift,
	&msrq->buf);
	mlx4_db_free(dev->dev, &msrq->db);
	}

	kfree(msrq);

	return 0;
	}

	void mlx4_ib_free_srq_wqe(struct mlx4_ib_srq *srq, int wqe_index)
	{
	struct mlx4_wqe_srq_next_seg *next;

	/* always called with interrupts disabled. */
	spin_lock(&srq->lock);

	next = get_wqe(srq, srq->tail);
	next->next_wqe_index = cpu_to_be16(wqe_index);
	srq->tail = wqe_index;

	spin_unlock(&srq->lock);
	}

	int mlx4_ib_post_srq_recv(struct ib_srq ibsrq, struct ib_recv_wr wr,
	struct ib_recv_wr **bad_wr)
	{
	struct mlx4_ib_srq *srq = to_msrq(ibsrq);
	struct mlx4_wqe_srq_next_seg *next;
	struct mlx4_wqe_data_seg *scat;
	unsigned long flags;
	int err = 0;
	int nreq;
	int i;

	spin_lock_irqsave(&srq->lock, flags);

	for (nreq = 0; wr; ++nreq, wr = wr->next) {
	if (unlikely(wr->num_sge > srq->msrq.max_gs)) {
	err = -EINVAL;
	*bad_wr = wr;
	break;
	}

	if (unlikely(srq->head == srq->tail)) {
	err = -ENOMEM;
	*bad_wr = wr;
	break;
	}

	srq->wrid[srq->head] = wr->wr_id;

	next = get_wqe(srq, srq->head);
	srq->head = be16_to_cpu(next->next_wqe_index);
	scat = (struct mlx4_wqe_data_seg *) (next + 1);

	for (i = 0; i < wr->num_sge; ++i) {
	scat[i].byte_count = cpu_to_be32(wr->sg_list[i].length);
	scat[i].lkey = cpu_to_be32(wr->sg_list[i].lkey);
	scat[i].addr = cpu_to_be64(wr->sg_list[i].addr);
	}

	if (i < srq->msrq.max_gs) {
	scat[i].byte_count = 0;
	scat[i].lkey = cpu_to_be32(MLX4_INVALID_LKEY);
	scat[i].addr = 0;
	}
	}

	if (likely(nreq)) {
	srq->wqe_ctr += nreq;

	/*
	* Make sure that descriptors are written before
	* doorbell record.
	*/
	wmb();

	*srq->db.db = cpu_to_be32(srq->wqe_ctr);
	}

	spin_unlock_irqrestore(&srq->lock, flags);

	return err;
	}