drivers/infiniband/hw/ipath/ipath_cq.c - maze/linux - Git at Google

 /*
  * Copyright (c) 2006 QLogic, Inc. All rights reserved.
  * Copyright (c) 2005, 2006 PathScale, 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/err.h>
 #include <linux/vmalloc.h>

 #include "ipath_verbs.h"

 /**
  * ipath_cq_enter - add a new entry to the completion queue
  * @cq: completion queue
  * @entry: work completion entry to add
  * @sig: true if @entry is a solicitated entry
  *
  * This may be called with qp->s_lock held.
  */
 void ipath_cq_enter(struct ipath_cq *cq, struct ib_wc *entry, int solicited)
 {
 	struct ipath_cq_wc *wc = cq->queue;
 	unsigned long flags;
 	u32 head;
 	u32 next;

 	spin_lock_irqsave(&cq->lock, flags);

 	/*
 	 * Note that the head pointer might be writable by user processes.
 	 * Take care to verify it is a sane value.
 	 */
 	head = wc->head;
 	if (head >= (unsigned) cq->ibcq.cqe) {
 		head = cq->ibcq.cqe;
 		next = 0;
 	} else
 		next = head + 1;
 	if (unlikely(next == wc->tail)) {
 		spin_unlock_irqrestore(&cq->lock, flags);
 		if (cq->ibcq.event_handler) {
 			struct ib_event ev;

 			ev.device = cq->ibcq.device;
 			ev.element.cq = &cq->ibcq;
 			ev.event = IB_EVENT_CQ_ERR;
 			cq->ibcq.event_handler(&ev, cq->ibcq.cq_context);
 		}
 		return;
 	}
 	wc->queue[head] = *entry;
 	wc->head = next;

 	if (cq->notify == IB_CQ_NEXT_COMP ||
 	    (cq->notify == IB_CQ_SOLICITED && solicited)) {
 		cq->notify = IB_CQ_NONE;
 		cq->triggered++;
 		/*
 		 * This will cause send_complete() to be called in
 		 * another thread.
 		 */
 		tasklet_hi_schedule(&cq->comptask);
 	}

 	spin_unlock_irqrestore(&cq->lock, flags);

 	if (entry->status != IB_WC_SUCCESS)
 		to_idev(cq->ibcq.device)->n_wqe_errs++;
 }

 /**
  * ipath_poll_cq - poll for work completion entries
  * @ibcq: the completion queue to poll
  * @num_entries: the maximum number of entries to return
  * @entry: pointer to array where work completions are placed
  *
  * Returns the number of completion entries polled.
  *
  * This may be called from interrupt context.  Also called by ib_poll_cq()
  * in the generic verbs code.
  */
 int ipath_poll_cq(struct ib_cq *ibcq, int num_entries, struct ib_wc *entry)
 {
 	struct ipath_cq *cq = to_icq(ibcq);
 	struct ipath_cq_wc *wc = cq->queue;
 	unsigned long flags;
 	int npolled;

 	spin_lock_irqsave(&cq->lock, flags);

 	for (npolled = 0; npolled < num_entries; ++npolled, ++entry) {
 		if (wc->tail == wc->head)
 			break;
 		*entry = wc->queue[wc->tail];
 		if (wc->tail >= cq->ibcq.cqe)
 			wc->tail = 0;
 		else
 			wc->tail++;
 	}

 	spin_unlock_irqrestore(&cq->lock, flags);

 	return npolled;
 }

 static void send_complete(unsigned long data)
 {
 	struct ipath_cq *cq = (struct ipath_cq *)data;

 	/*
 	 * The completion handler will most likely rearm the notification
 	 * and poll for all pending entries.  If a new completion entry
 	 * is added while we are in this routine, tasklet_hi_schedule()
 	 * won't call us again until we return so we check triggered to
 	 * see if we need to call the handler again.
 	 */
 	for (;;) {
 		u8 triggered = cq->triggered;

 		cq->ibcq.comp_handler(&cq->ibcq, cq->ibcq.cq_context);

 		if (cq->triggered == triggered)
 			return;
 	}
 }

 /**
  * ipath_create_cq - create a completion queue
  * @ibdev: the device this completion queue is attached to
  * @entries: the minimum size of the completion queue
  * @context: unused by the InfiniPath driver
  * @udata: unused by the InfiniPath driver
  *
  * Returns a pointer to the completion queue or negative errno values
  * for failure.
  *
  * Called by ib_create_cq() in the generic verbs code.
  */
 struct ib_cq *ipath_create_cq(struct ib_device *ibdev, int entries,
 			      struct ib_ucontext *context,
 			      struct ib_udata *udata)
 {
 	struct ipath_ibdev *dev = to_idev(ibdev);
 	struct ipath_cq *cq;
 	struct ipath_cq_wc *wc;
 	struct ib_cq *ret;

 	if (entries < 1 || entries > ib_ipath_max_cqes) {
 		ret = ERR_PTR(-EINVAL);
 		goto done;
 	}

 	if (dev->n_cqs_allocated == ib_ipath_max_cqs) {
 		ret = ERR_PTR(-ENOMEM);
 		goto done;
 	}

 	/* Allocate the completion queue structure. */
 	cq = kmalloc(sizeof(*cq), GFP_KERNEL);
 	if (!cq) {
 		ret = ERR_PTR(-ENOMEM);
 		goto done;
 	}

 	/*
 	 * Allocate the completion queue entries and head/tail pointers.
 	 * This is allocated separately so that it can be resized and
 	 * also mapped into user space.
 	 * We need to use vmalloc() in order to support mmap and large
 	 * numbers of entries.
 	 */
 	wc = vmalloc_user(sizeof(*wc) + sizeof(struct ib_wc) * entries);
 	if (!wc) {
 		ret = ERR_PTR(-ENOMEM);
 		goto bail_cq;
 	}

 	/*
 	 * Return the address of the WC as the offset to mmap.
 	 * See ipath_mmap() for details.
 	 */
 	if (udata && udata->outlen >= sizeof(__u64)) {
 		struct ipath_mmap_info *ip;
 		__u64 offset = (__u64) wc;
 		int err;

 		err = ib_copy_to_udata(udata, &offset, sizeof(offset));
 		if (err) {
 			ret = ERR_PTR(err);
 			goto bail_wc;
 		}

 		/* Allocate info for ipath_mmap(). */
 		ip = kmalloc(sizeof(*ip), GFP_KERNEL);
 		if (!ip) {
 			ret = ERR_PTR(-ENOMEM);
 			goto bail_wc;
 		}
 		cq->ip = ip;
 		ip->context = context;
 		ip->obj = wc;
 		kref_init(&ip->ref);
 		ip->mmap_cnt = 0;
 		ip->size = PAGE_ALIGN(sizeof(*wc) +
 				      sizeof(struct ib_wc) * entries);
 		spin_lock_irq(&dev->pending_lock);
 		ip->next = dev->pending_mmaps;
 		dev->pending_mmaps = ip;
 		spin_unlock_irq(&dev->pending_lock);
 	} else
 		cq->ip = NULL;

 	/*
 	 * ib_create_cq() will initialize cq->ibcq except for cq->ibcq.cqe.
 	 * The number of entries should be >= the number requested or return
 	 * an error.
 	 */
 	cq->ibcq.cqe = entries;
 	cq->notify = IB_CQ_NONE;
 	cq->triggered = 0;
 	spin_lock_init(&cq->lock);
 	tasklet_init(&cq->comptask, send_complete, (unsigned long)cq);
 	wc->head = 0;
 	wc->tail = 0;
 	cq->queue = wc;

 	ret = &cq->ibcq;

 	dev->n_cqs_allocated++;
 	goto done;

 bail_wc:
 	vfree(wc);

 bail_cq:
 	kfree(cq);

 done:
 	return ret;
 }

 /**
  * ipath_destroy_cq - destroy a completion queue
  * @ibcq: the completion queue to destroy.
  *
  * Returns 0 for success.
  *
  * Called by ib_destroy_cq() in the generic verbs code.
  */
 int ipath_destroy_cq(struct ib_cq *ibcq)
 {
 	struct ipath_ibdev *dev = to_idev(ibcq->device);
 	struct ipath_cq *cq = to_icq(ibcq);

 	tasklet_kill(&cq->comptask);
 	dev->n_cqs_allocated--;
 	if (cq->ip)
 		kref_put(&cq->ip->ref, ipath_release_mmap_info);
 	else
 		vfree(cq->queue);
 	kfree(cq);

 	return 0;
 }

 /**
  * ipath_req_notify_cq - change the notification type for a completion queue
  * @ibcq: the completion queue
  * @notify: the type of notification to request
  *
  * Returns 0 for success.
  *
  * This may be called from interrupt context.  Also called by
  * ib_req_notify_cq() in the generic verbs code.
  */
 int ipath_req_notify_cq(struct ib_cq *ibcq, enum ib_cq_notify notify)
 {
 	struct ipath_cq *cq = to_icq(ibcq);
 	unsigned long flags;

 	spin_lock_irqsave(&cq->lock, flags);
 	/*
 	 * Don't change IB_CQ_NEXT_COMP to IB_CQ_SOLICITED but allow
 	 * any other transitions (see C11-31 and C11-32 in ch. 11.4.2.2).
 	 */
 	if (cq->notify != IB_CQ_NEXT_COMP)
 		cq->notify = notify;
 	spin_unlock_irqrestore(&cq->lock, flags);
 	return 0;
 }

 int ipath_resize_cq(struct ib_cq *ibcq, int cqe, struct ib_udata *udata)
 {
 	struct ipath_cq *cq = to_icq(ibcq);
 	struct ipath_cq_wc *old_wc = cq->queue;
 	struct ipath_cq_wc *wc;
 	u32 head, tail, n;
 	int ret;

 	if (cqe < 1 || cqe > ib_ipath_max_cqes) {
 		ret = -EINVAL;
 		goto bail;
 	}

 	/*
 	 * Need to use vmalloc() if we want to support large #s of entries.
 	 */
 	wc = vmalloc_user(sizeof(*wc) + sizeof(struct ib_wc) * cqe);
 	if (!wc) {
 		ret = -ENOMEM;
 		goto bail;
 	}

 	/*
 	 * Return the address of the WC as the offset to mmap.
 	 * See ipath_mmap() for details.
 	 */
 	if (udata && udata->outlen >= sizeof(__u64)) {
 		__u64 offset = (__u64) wc;

 		ret = ib_copy_to_udata(udata, &offset, sizeof(offset));
 		if (ret)
 			goto bail;
 	}

 	spin_lock_irq(&cq->lock);
 	/*
 	 * Make sure head and tail are sane since they
 	 * might be user writable.
 	 */
 	head = old_wc->head;
 	if (head > (u32) cq->ibcq.cqe)
 		head = (u32) cq->ibcq.cqe;
 	tail = old_wc->tail;
 	if (tail > (u32) cq->ibcq.cqe)
 		tail = (u32) cq->ibcq.cqe;
 	if (head < tail)
 		n = cq->ibcq.cqe + 1 + head - tail;
 	else
 		n = head - tail;
 	if (unlikely((u32)cqe < n)) {
 		spin_unlock_irq(&cq->lock);
 		vfree(wc);
 		ret = -EOVERFLOW;
 		goto bail;
 	}
 	for (n = 0; tail != head; n++) {
 		wc->queue[n] = old_wc->queue[tail];
 		if (tail == (u32) cq->ibcq.cqe)
 			tail = 0;
 		else
 			tail++;
 	}
 	cq->ibcq.cqe = cqe;
 	wc->head = n;
 	wc->tail = 0;
 	cq->queue = wc;
 	spin_unlock_irq(&cq->lock);

 	vfree(old_wc);

 	if (cq->ip) {
 		struct ipath_ibdev *dev = to_idev(ibcq->device);
 		struct ipath_mmap_info *ip = cq->ip;

 		ip->obj = wc;
 		ip->size = PAGE_ALIGN(sizeof(*wc) +
 				      sizeof(struct ib_wc) * cqe);
 		spin_lock_irq(&dev->pending_lock);
 		ip->next = dev->pending_mmaps;
 		dev->pending_mmaps = ip;
 		spin_unlock_irq(&dev->pending_lock);
 	}

 	ret = 0;

 bail:
 	return ret;
 }
	/*
	* Copyright (c) 2006 QLogic, Inc. All rights reserved.
	* Copyright (c) 2005, 2006 PathScale, 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/err.h>
	#include <linux/vmalloc.h>

	#include "ipath_verbs.h"

	/**
	* ipath_cq_enter - add a new entry to the completion queue
	* @cq: completion queue
	* @entry: work completion entry to add
	* @sig: true if @entry is a solicitated entry
	*
	* This may be called with qp->s_lock held.
	*/
	void ipath_cq_enter(struct ipath_cq cq, struct ib_wc entry, int solicited)
	{
	struct ipath_cq_wc *wc = cq->queue;
	unsigned long flags;
	u32 head;
	u32 next;

	spin_lock_irqsave(&cq->lock, flags);

	/*
	* Note that the head pointer might be writable by user processes.
	* Take care to verify it is a sane value.
	*/
	head = wc->head;
	if (head >= (unsigned) cq->ibcq.cqe) {
	head = cq->ibcq.cqe;
	next = 0;
	} else
	next = head + 1;
	if (unlikely(next == wc->tail)) {
	spin_unlock_irqrestore(&cq->lock, flags);
	if (cq->ibcq.event_handler) {
	struct ib_event ev;

	ev.device = cq->ibcq.device;
	ev.element.cq = &cq->ibcq;
	ev.event = IB_EVENT_CQ_ERR;
	cq->ibcq.event_handler(&ev, cq->ibcq.cq_context);
	}
	return;
	}
	wc->queue[head] = *entry;
	wc->head = next;

	if (cq->notify == IB_CQ_NEXT_COMP \|\|
	(cq->notify == IB_CQ_SOLICITED && solicited)) {
	cq->notify = IB_CQ_NONE;
	cq->triggered++;
	/*
	* This will cause send_complete() to be called in
	* another thread.
	*/
	tasklet_hi_schedule(&cq->comptask);
	}

	spin_unlock_irqrestore(&cq->lock, flags);

	if (entry->status != IB_WC_SUCCESS)
	to_idev(cq->ibcq.device)->n_wqe_errs++;
	}

	/**
	* ipath_poll_cq - poll for work completion entries
	* @ibcq: the completion queue to poll
	* @num_entries: the maximum number of entries to return
	* @entry: pointer to array where work completions are placed
	*
	* Returns the number of completion entries polled.
	*
	* This may be called from interrupt context. Also called by ib_poll_cq()
	* in the generic verbs code.
	*/
	int ipath_poll_cq(struct ib_cq ibcq, int num_entries, struct ib_wc entry)
	{
	struct ipath_cq *cq = to_icq(ibcq);
	struct ipath_cq_wc *wc = cq->queue;
	unsigned long flags;
	int npolled;

	spin_lock_irqsave(&cq->lock, flags);

	for (npolled = 0; npolled < num_entries; ++npolled, ++entry) {
	if (wc->tail == wc->head)
	break;
	*entry = wc->queue[wc->tail];
	if (wc->tail >= cq->ibcq.cqe)
	wc->tail = 0;
	else
	wc->tail++;
	}

	spin_unlock_irqrestore(&cq->lock, flags);

	return npolled;
	}

	static void send_complete(unsigned long data)
	{
	struct ipath_cq cq = (struct ipath_cq )data;

	/*
	* The completion handler will most likely rearm the notification
	* and poll for all pending entries. If a new completion entry
	* is added while we are in this routine, tasklet_hi_schedule()
	* won't call us again until we return so we check triggered to
	* see if we need to call the handler again.
	*/
	for (;;) {
	u8 triggered = cq->triggered;

	cq->ibcq.comp_handler(&cq->ibcq, cq->ibcq.cq_context);

	if (cq->triggered == triggered)
	return;
	}
	}

	/**
	* ipath_create_cq - create a completion queue
	* @ibdev: the device this completion queue is attached to
	* @entries: the minimum size of the completion queue
	* @context: unused by the InfiniPath driver
	* @udata: unused by the InfiniPath driver
	*
	* Returns a pointer to the completion queue or negative errno values
	* for failure.
	*
	* Called by ib_create_cq() in the generic verbs code.
	*/
	struct ib_cq ipath_create_cq(struct ib_device ibdev, int entries,
	struct ib_ucontext *context,
	struct ib_udata *udata)
	{
	struct ipath_ibdev *dev = to_idev(ibdev);
	struct ipath_cq *cq;
	struct ipath_cq_wc *wc;
	struct ib_cq *ret;

	if (entries < 1 \|\| entries > ib_ipath_max_cqes) {
	ret = ERR_PTR(-EINVAL);
	goto done;
	}

	if (dev->n_cqs_allocated == ib_ipath_max_cqs) {
	ret = ERR_PTR(-ENOMEM);
	goto done;
	}

	/* Allocate the completion queue structure. */
	cq = kmalloc(sizeof(*cq), GFP_KERNEL);
	if (!cq) {
	ret = ERR_PTR(-ENOMEM);
	goto done;
	}

	/*
	* Allocate the completion queue entries and head/tail pointers.
	* This is allocated separately so that it can be resized and
	* also mapped into user space.
	* We need to use vmalloc() in order to support mmap and large
	* numbers of entries.
	*/
	wc = vmalloc_user(sizeof(wc) + sizeof(struct ib_wc) entries);
	if (!wc) {
	ret = ERR_PTR(-ENOMEM);
	goto bail_cq;
	}

	/*
	* Return the address of the WC as the offset to mmap.
	* See ipath_mmap() for details.
	*/
	if (udata && udata->outlen >= sizeof(__u64)) {
	struct ipath_mmap_info *ip;
	__u64 offset = (__u64) wc;
	int err;

	err = ib_copy_to_udata(udata, &offset, sizeof(offset));
	if (err) {
	ret = ERR_PTR(err);
	goto bail_wc;
	}

	/* Allocate info for ipath_mmap(). */
	ip = kmalloc(sizeof(*ip), GFP_KERNEL);
	if (!ip) {
	ret = ERR_PTR(-ENOMEM);
	goto bail_wc;
	}
	cq->ip = ip;
	ip->context = context;
	ip->obj = wc;
	kref_init(&ip->ref);
	ip->mmap_cnt = 0;
	ip->size = PAGE_ALIGN(sizeof(*wc) +
	sizeof(struct ib_wc) * entries);
	spin_lock_irq(&dev->pending_lock);
	ip->next = dev->pending_mmaps;
	dev->pending_mmaps = ip;
	spin_unlock_irq(&dev->pending_lock);
	} else
	cq->ip = NULL;

	/*
	* ib_create_cq() will initialize cq->ibcq except for cq->ibcq.cqe.
	* The number of entries should be >= the number requested or return
	* an error.
	*/
	cq->ibcq.cqe = entries;
	cq->notify = IB_CQ_NONE;
	cq->triggered = 0;
	spin_lock_init(&cq->lock);
	tasklet_init(&cq->comptask, send_complete, (unsigned long)cq);
	wc->head = 0;
	wc->tail = 0;
	cq->queue = wc;

	ret = &cq->ibcq;

	dev->n_cqs_allocated++;
	goto done;

	bail_wc:
	vfree(wc);

	bail_cq:
	kfree(cq);

	done:
	return ret;
	}

	/**
	* ipath_destroy_cq - destroy a completion queue
	* @ibcq: the completion queue to destroy.
	*
	* Returns 0 for success.
	*
	* Called by ib_destroy_cq() in the generic verbs code.
	*/
	int ipath_destroy_cq(struct ib_cq *ibcq)
	{
	struct ipath_ibdev *dev = to_idev(ibcq->device);
	struct ipath_cq *cq = to_icq(ibcq);

	tasklet_kill(&cq->comptask);
	dev->n_cqs_allocated--;
	if (cq->ip)
	kref_put(&cq->ip->ref, ipath_release_mmap_info);
	else
	vfree(cq->queue);
	kfree(cq);

	return 0;
	}

	/**
	* ipath_req_notify_cq - change the notification type for a completion queue
	* @ibcq: the completion queue
	* @notify: the type of notification to request
	*
	* Returns 0 for success.
	*
	* This may be called from interrupt context. Also called by
	* ib_req_notify_cq() in the generic verbs code.
	*/
	int ipath_req_notify_cq(struct ib_cq *ibcq, enum ib_cq_notify notify)
	{
	struct ipath_cq *cq = to_icq(ibcq);
	unsigned long flags;

	spin_lock_irqsave(&cq->lock, flags);
	/*
	* Don't change IB_CQ_NEXT_COMP to IB_CQ_SOLICITED but allow
	* any other transitions (see C11-31 and C11-32 in ch. 11.4.2.2).
	*/
	if (cq->notify != IB_CQ_NEXT_COMP)
	cq->notify = notify;
	spin_unlock_irqrestore(&cq->lock, flags);
	return 0;
	}

	int ipath_resize_cq(struct ib_cq ibcq, int cqe, struct ib_udata udata)
	{
	struct ipath_cq *cq = to_icq(ibcq);
	struct ipath_cq_wc *old_wc = cq->queue;
	struct ipath_cq_wc *wc;
	u32 head, tail, n;
	int ret;

	if (cqe < 1 \|\| cqe > ib_ipath_max_cqes) {
	ret = -EINVAL;
	goto bail;
	}

	/*
	* Need to use vmalloc() if we want to support large #s of entries.
	*/
	wc = vmalloc_user(sizeof(wc) + sizeof(struct ib_wc) cqe);
	if (!wc) {
	ret = -ENOMEM;
	goto bail;
	}

	/*
	* Return the address of the WC as the offset to mmap.
	* See ipath_mmap() for details.
	*/
	if (udata && udata->outlen >= sizeof(__u64)) {
	__u64 offset = (__u64) wc;

	ret = ib_copy_to_udata(udata, &offset, sizeof(offset));
	if (ret)
	goto bail;
	}

	spin_lock_irq(&cq->lock);
	/*
	* Make sure head and tail are sane since they
	* might be user writable.
	*/
	head = old_wc->head;
	if (head > (u32) cq->ibcq.cqe)
	head = (u32) cq->ibcq.cqe;
	tail = old_wc->tail;
	if (tail > (u32) cq->ibcq.cqe)
	tail = (u32) cq->ibcq.cqe;
	if (head < tail)
	n = cq->ibcq.cqe + 1 + head - tail;
	else
	n = head - tail;
	if (unlikely((u32)cqe < n)) {
	spin_unlock_irq(&cq->lock);
	vfree(wc);
	ret = -EOVERFLOW;
	goto bail;
	}
	for (n = 0; tail != head; n++) {
	wc->queue[n] = old_wc->queue[tail];
	if (tail == (u32) cq->ibcq.cqe)
	tail = 0;
	else
	tail++;
	}
	cq->ibcq.cqe = cqe;
	wc->head = n;
	wc->tail = 0;
	cq->queue = wc;
	spin_unlock_irq(&cq->lock);

	vfree(old_wc);

	if (cq->ip) {
	struct ipath_ibdev *dev = to_idev(ibcq->device);
	struct ipath_mmap_info *ip = cq->ip;

	ip->obj = wc;
	ip->size = PAGE_ALIGN(sizeof(*wc) +
	sizeof(struct ib_wc) * cqe);
	spin_lock_irq(&dev->pending_lock);
	ip->next = dev->pending_mmaps;
	dev->pending_mmaps = ip;
	spin_unlock_irq(&dev->pending_lock);
	}

	ret = 0;

	bail:
	return ret;
	}