Contributors: 15
Author Tokens Token Proportion Commits Commit Proportion
Roland Dreier 3042 80.18% 18 46.15%
Michael S. Tsirkin 624 16.45% 5 12.82%
Jens Axboe 72 1.90% 2 5.13%
Kees Cook 17 0.45% 2 5.13%
Ishai Rabinovitz 15 0.40% 1 2.56%
Jack Morgenstein 5 0.13% 1 2.56%
Tejun Heo 3 0.08% 1 2.56%
Al Viro 3 0.08% 2 5.13%
Alexey Dobriyan 3 0.08% 1 2.56%
Eli Cohen 3 0.08% 1 2.56%
Ira Weiny 2 0.05% 1 2.56%
Sean Hefty 2 0.05% 1 2.56%
Davidlohr Bueso A 1 0.03% 1 2.56%
Lorenzo Stoakes 1 0.03% 1 2.56%
Luis R. Rodriguez 1 0.03% 1 2.56%
Total 3794 39 


/*
 * Copyright (c) 2004, 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Cisco Systems.  All rights reserved.
 * Copyright (c) 2005 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/mm.h>
#include <linux/scatterlist.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include <asm/page.h>

#include "mthca_memfree.h"
#include "mthca_dev.h"
#include "mthca_cmd.h"

/*
 * We allocate in as big chunks as we can, up to a maximum of 256 KB
 * per chunk.
 */
enum {
	MTHCA_ICM_ALLOC_SIZE   = 1 << 18,
	MTHCA_TABLE_CHUNK_SIZE = 1 << 18
};

struct mthca_user_db_table {
	struct mutex mutex;
	struct {
		u64                uvirt;
		struct scatterlist mem;
		int                refcount;
	}                page[0];
};

static void mthca_free_icm_pages(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)
{
	int i;

	if (chunk->nsg > 0)
		pci_unmap_sg(dev->pdev, chunk->mem, chunk->npages,
			     PCI_DMA_BIDIRECTIONAL);

	for (i = 0; i < chunk->npages; ++i)
		__free_pages(sg_page(&chunk->mem[i]),
			     get_order(chunk->mem[i].length));
}

static void mthca_free_icm_coherent(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)
{
	int i;

	for (i = 0; i < chunk->npages; ++i) {
		dma_free_coherent(&dev->pdev->dev, chunk->mem[i].length,
				  lowmem_page_address(sg_page(&chunk->mem[i])),
				  sg_dma_address(&chunk->mem[i]));
	}
}

void mthca_free_icm(struct mthca_dev *dev, struct mthca_icm *icm, int coherent)
{
	struct mthca_icm_chunk *chunk, *tmp;

	if (!icm)
		return;

	list_for_each_entry_safe(chunk, tmp, &icm->chunk_list, list) {
		if (coherent)
			mthca_free_icm_coherent(dev, chunk);
		else
			mthca_free_icm_pages(dev, chunk);

		kfree(chunk);
	}

	kfree(icm);
}

static int mthca_alloc_icm_pages(struct scatterlist *mem, int order, gfp_t gfp_mask)
{
	struct page *page;

	/*
	 * Use __GFP_ZERO because buggy firmware assumes ICM pages are
	 * cleared, and subtle failures are seen if they aren't.
	 */
	page = alloc_pages(gfp_mask | __GFP_ZERO, order);
	if (!page)
		return -ENOMEM;

	sg_set_page(mem, page, PAGE_SIZE << order, 0);
	return 0;
}

static int mthca_alloc_icm_coherent(struct device *dev, struct scatterlist *mem,
				    int order, gfp_t gfp_mask)
{
	void *buf = dma_alloc_coherent(dev, PAGE_SIZE << order, &sg_dma_address(mem),
				       gfp_mask);
	if (!buf)
		return -ENOMEM;

	sg_set_buf(mem, buf, PAGE_SIZE << order);
	BUG_ON(mem->offset);
	sg_dma_len(mem) = PAGE_SIZE << order;
	return 0;
}

struct mthca_icm *mthca_alloc_icm(struct mthca_dev *dev, int npages,
				  gfp_t gfp_mask, int coherent)
{
	struct mthca_icm *icm;
	struct mthca_icm_chunk *chunk = NULL;
	int cur_order;
	int ret;

	/* We use sg_set_buf for coherent allocs, which assumes low memory */
	BUG_ON(coherent && (gfp_mask & __GFP_HIGHMEM));

	icm = kmalloc(sizeof *icm, gfp_mask & ~(__GFP_HIGHMEM | __GFP_NOWARN));
	if (!icm)
		return icm;

	icm->refcount = 0;
	INIT_LIST_HEAD(&icm->chunk_list);

	cur_order = get_order(MTHCA_ICM_ALLOC_SIZE);

	while (npages > 0) {
		if (!chunk) {
			chunk = kmalloc(sizeof *chunk,
					gfp_mask & ~(__GFP_HIGHMEM | __GFP_NOWARN));
			if (!chunk)
				goto fail;

			sg_init_table(chunk->mem, MTHCA_ICM_CHUNK_LEN);
			chunk->npages = 0;
			chunk->nsg    = 0;
			list_add_tail(&chunk->list, &icm->chunk_list);
		}

		while (1 << cur_order > npages)
			--cur_order;

		if (coherent)
			ret = mthca_alloc_icm_coherent(&dev->pdev->dev,
						       &chunk->mem[chunk->npages],
						       cur_order, gfp_mask);
		else
			ret = mthca_alloc_icm_pages(&chunk->mem[chunk->npages],
						    cur_order, gfp_mask);

		if (!ret) {
			++chunk->npages;

			if (coherent)
				++chunk->nsg;
			else if (chunk->npages == MTHCA_ICM_CHUNK_LEN) {
				chunk->nsg = pci_map_sg(dev->pdev, chunk->mem,
							chunk->npages,
							PCI_DMA_BIDIRECTIONAL);

				if (chunk->nsg <= 0)
					goto fail;
			}

			if (chunk->npages == MTHCA_ICM_CHUNK_LEN)
				chunk = NULL;

			npages -= 1 << cur_order;
		} else {
			--cur_order;
			if (cur_order < 0)
				goto fail;
		}
	}

	if (!coherent && chunk) {
		chunk->nsg = pci_map_sg(dev->pdev, chunk->mem,
					chunk->npages,
					PCI_DMA_BIDIRECTIONAL);

		if (chunk->nsg <= 0)
			goto fail;
	}

	return icm;

fail:
	mthca_free_icm(dev, icm, coherent);
	return NULL;
}

int mthca_table_get(struct mthca_dev *dev, struct mthca_icm_table *table, int obj)
{
	int i = (obj & (table->num_obj - 1)) * table->obj_size / MTHCA_TABLE_CHUNK_SIZE;
	int ret = 0;

	mutex_lock(&table->mutex);

	if (table->icm[i]) {
		++table->icm[i]->refcount;
		goto out;
	}

	table->icm[i] = mthca_alloc_icm(dev, MTHCA_TABLE_CHUNK_SIZE >> PAGE_SHIFT,
					(table->lowmem ? GFP_KERNEL : GFP_HIGHUSER) |
					__GFP_NOWARN, table->coherent);
	if (!table->icm[i]) {
		ret = -ENOMEM;
		goto out;
	}

	if (mthca_MAP_ICM(dev, table->icm[i],
			  table->virt + i * MTHCA_TABLE_CHUNK_SIZE)) {
		mthca_free_icm(dev, table->icm[i], table->coherent);
		table->icm[i] = NULL;
		ret = -ENOMEM;
		goto out;
	}

	++table->icm[i]->refcount;

out:
	mutex_unlock(&table->mutex);
	return ret;
}

void mthca_table_put(struct mthca_dev *dev, struct mthca_icm_table *table, int obj)
{
	int i;

	if (!mthca_is_memfree(dev))
		return;

	i = (obj & (table->num_obj - 1)) * table->obj_size / MTHCA_TABLE_CHUNK_SIZE;

	mutex_lock(&table->mutex);

	if (--table->icm[i]->refcount == 0) {
		mthca_UNMAP_ICM(dev, table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
				MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE);
		mthca_free_icm(dev, table->icm[i], table->coherent);
		table->icm[i] = NULL;
	}

	mutex_unlock(&table->mutex);
}

void *mthca_table_find(struct mthca_icm_table *table, int obj, dma_addr_t *dma_handle)
{
	int idx, offset, dma_offset, i;
	struct mthca_icm_chunk *chunk;
	struct mthca_icm *icm;
	struct page *page = NULL;

	if (!table->lowmem)
		return NULL;

	mutex_lock(&table->mutex);

	idx = (obj & (table->num_obj - 1)) * table->obj_size;
	icm = table->icm[idx / MTHCA_TABLE_CHUNK_SIZE];
	dma_offset = offset = idx % MTHCA_TABLE_CHUNK_SIZE;

	if (!icm)
		goto out;

	list_for_each_entry(chunk, &icm->chunk_list, list) {
		for (i = 0; i < chunk->npages; ++i) {
			if (dma_handle && dma_offset >= 0) {
				if (sg_dma_len(&chunk->mem[i]) > dma_offset)
					*dma_handle = sg_dma_address(&chunk->mem[i]) +
						dma_offset;
				dma_offset -= sg_dma_len(&chunk->mem[i]);
			}
			/* DMA mapping can merge pages but not split them,
			 * so if we found the page, dma_handle has already
			 * been assigned to. */
			if (chunk->mem[i].length > offset) {
				page = sg_page(&chunk->mem[i]);
				goto out;
			}
			offset -= chunk->mem[i].length;
		}
	}

out:
	mutex_unlock(&table->mutex);
	return page ? lowmem_page_address(page) + offset : NULL;
}

int mthca_table_get_range(struct mthca_dev *dev, struct mthca_icm_table *table,
			  int start, int end)
{
	int inc = MTHCA_TABLE_CHUNK_SIZE / table->obj_size;
	int i, err;

	for (i = start; i <= end; i += inc) {
		err = mthca_table_get(dev, table, i);
		if (err)
			goto fail;
	}

	return 0;

fail:
	while (i > start) {
		i -= inc;
		mthca_table_put(dev, table, i);
	}

	return err;
}

void mthca_table_put_range(struct mthca_dev *dev, struct mthca_icm_table *table,
			   int start, int end)
{
	int i;

	if (!mthca_is_memfree(dev))
		return;

	for (i = start; i <= end; i += MTHCA_TABLE_CHUNK_SIZE / table->obj_size)
		mthca_table_put(dev, table, i);
}

struct mthca_icm_table *mthca_alloc_icm_table(struct mthca_dev *dev,
					      u64 virt, int obj_size,
					      int nobj, int reserved,
					      int use_lowmem, int use_coherent)
{
	struct mthca_icm_table *table;
	int obj_per_chunk;
	int num_icm;
	unsigned chunk_size;
	int i;

	obj_per_chunk = MTHCA_TABLE_CHUNK_SIZE / obj_size;
	num_icm = DIV_ROUND_UP(nobj, obj_per_chunk);

	table = kmalloc(struct_size(table, icm, num_icm), GFP_KERNEL);
	if (!table)
		return NULL;

	table->virt     = virt;
	table->num_icm  = num_icm;
	table->num_obj  = nobj;
	table->obj_size = obj_size;
	table->lowmem   = use_lowmem;
	table->coherent = use_coherent;
	mutex_init(&table->mutex);

	for (i = 0; i < num_icm; ++i)
		table->icm[i] = NULL;

	for (i = 0; i * MTHCA_TABLE_CHUNK_SIZE < reserved * obj_size; ++i) {
		chunk_size = MTHCA_TABLE_CHUNK_SIZE;
		if ((i + 1) * MTHCA_TABLE_CHUNK_SIZE > nobj * obj_size)
			chunk_size = nobj * obj_size - i * MTHCA_TABLE_CHUNK_SIZE;

		table->icm[i] = mthca_alloc_icm(dev, chunk_size >> PAGE_SHIFT,
						(use_lowmem ? GFP_KERNEL : GFP_HIGHUSER) |
						__GFP_NOWARN, use_coherent);
		if (!table->icm[i])
			goto err;
		if (mthca_MAP_ICM(dev, table->icm[i],
				  virt + i * MTHCA_TABLE_CHUNK_SIZE)) {
			mthca_free_icm(dev, table->icm[i], table->coherent);
			table->icm[i] = NULL;
			goto err;
		}

		/*
		 * Add a reference to this ICM chunk so that it never
		 * gets freed (since it contains reserved firmware objects).
		 */
		++table->icm[i]->refcount;
	}

	return table;

err:
	for (i = 0; i < num_icm; ++i)
		if (table->icm[i]) {
			mthca_UNMAP_ICM(dev, virt + i * MTHCA_TABLE_CHUNK_SIZE,
					MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE);
			mthca_free_icm(dev, table->icm[i], table->coherent);
		}

	kfree(table);

	return NULL;
}

void mthca_free_icm_table(struct mthca_dev *dev, struct mthca_icm_table *table)
{
	int i;

	for (i = 0; i < table->num_icm; ++i)
		if (table->icm[i]) {
			mthca_UNMAP_ICM(dev,
					table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
					MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE);
			mthca_free_icm(dev, table->icm[i], table->coherent);
		}

	kfree(table);
}

static u64 mthca_uarc_virt(struct mthca_dev *dev, struct mthca_uar *uar, int page)
{
	return dev->uar_table.uarc_base +
		uar->index * dev->uar_table.uarc_size +
		page * MTHCA_ICM_PAGE_SIZE;
}

int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
		      struct mthca_user_db_table *db_tab, int index, u64 uaddr)
{
	struct page *pages[1];
	int ret = 0;
	int i;

	if (!mthca_is_memfree(dev))
		return 0;

	if (index < 0 || index > dev->uar_table.uarc_size / 8)
		return -EINVAL;

	mutex_lock(&db_tab->mutex);

	i = index / MTHCA_DB_REC_PER_PAGE;

	if ((db_tab->page[i].refcount >= MTHCA_DB_REC_PER_PAGE)       ||
	    (db_tab->page[i].uvirt && db_tab->page[i].uvirt != uaddr) ||
	    (uaddr & 4095)) {
		ret = -EINVAL;
		goto out;
	}

	if (db_tab->page[i].refcount) {
		++db_tab->page[i].refcount;
		goto out;
	}

	ret = get_user_pages_fast(uaddr & PAGE_MASK, 1,
				  FOLL_WRITE | FOLL_LONGTERM, pages);
	if (ret < 0)
		goto out;

	sg_set_page(&db_tab->page[i].mem, pages[0], MTHCA_ICM_PAGE_SIZE,
			uaddr & ~PAGE_MASK);

	ret = pci_map_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
	if (ret < 0) {
		put_page(pages[0]);
		goto out;
	}

	ret = mthca_MAP_ICM_page(dev, sg_dma_address(&db_tab->page[i].mem),
				 mthca_uarc_virt(dev, uar, i));
	if (ret) {
		pci_unmap_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
		put_page(sg_page(&db_tab->page[i].mem));
		goto out;
	}

	db_tab->page[i].uvirt    = uaddr;
	db_tab->page[i].refcount = 1;

out:
	mutex_unlock(&db_tab->mutex);
	return ret;
}

void mthca_unmap_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
			 struct mthca_user_db_table *db_tab, int index)
{
	if (!mthca_is_memfree(dev))
		return;

	/*
	 * To make our bookkeeping simpler, we don't unmap DB
	 * pages until we clean up the whole db table.
	 */

	mutex_lock(&db_tab->mutex);

	--db_tab->page[index / MTHCA_DB_REC_PER_PAGE].refcount;

	mutex_unlock(&db_tab->mutex);
}

struct mthca_user_db_table *mthca_init_user_db_tab(struct mthca_dev *dev)
{
	struct mthca_user_db_table *db_tab;
	int npages;
	int i;

	if (!mthca_is_memfree(dev))
		return NULL;

	npages = dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE;
	db_tab = kmalloc(struct_size(db_tab, page, npages), GFP_KERNEL);
	if (!db_tab)
		return ERR_PTR(-ENOMEM);

	mutex_init(&db_tab->mutex);
	for (i = 0; i < npages; ++i) {
		db_tab->page[i].refcount = 0;
		db_tab->page[i].uvirt    = 0;
		sg_init_table(&db_tab->page[i].mem, 1);
	}

	return db_tab;
}

void mthca_cleanup_user_db_tab(struct mthca_dev *dev, struct mthca_uar *uar,
			       struct mthca_user_db_table *db_tab)
{
	int i;

	if (!mthca_is_memfree(dev))
		return;

	for (i = 0; i < dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE; ++i) {
		if (db_tab->page[i].uvirt) {
			mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, uar, i), 1);
			pci_unmap_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
			put_page(sg_page(&db_tab->page[i].mem));
		}
	}

	kfree(db_tab);
}

int mthca_alloc_db(struct mthca_dev *dev, enum mthca_db_type type,
		   u32 qn, __be32 **db)
{
	int group;
	int start, end, dir;
	int i, j;
	struct mthca_db_page *page;
	int ret = 0;

	mutex_lock(&dev->db_tab->mutex);

	switch (type) {
	case MTHCA_DB_TYPE_CQ_ARM:
	case MTHCA_DB_TYPE_SQ:
		group = 0;
		start = 0;
		end   = dev->db_tab->max_group1;
		dir   = 1;
		break;

	case MTHCA_DB_TYPE_CQ_SET_CI:
	case MTHCA_DB_TYPE_RQ:
	case MTHCA_DB_TYPE_SRQ:
		group = 1;
		start = dev->db_tab->npages - 1;
		end   = dev->db_tab->min_group2;
		dir   = -1;
		break;

	default:
		ret = -EINVAL;
		goto out;
	}

	for (i = start; i != end; i += dir)
		if (dev->db_tab->page[i].db_rec &&
		    !bitmap_full(dev->db_tab->page[i].used,
				 MTHCA_DB_REC_PER_PAGE)) {
			page = dev->db_tab->page + i;
			goto found;
		}

	for (i = start; i != end; i += dir)
		if (!dev->db_tab->page[i].db_rec) {
			page = dev->db_tab->page + i;
			goto alloc;
		}

	if (dev->db_tab->max_group1 >= dev->db_tab->min_group2 - 1) {
		ret = -ENOMEM;
		goto out;
	}

	if (group == 0)
		++dev->db_tab->max_group1;
	else
		--dev->db_tab->min_group2;

	page = dev->db_tab->page + end;

alloc:
	page->db_rec = dma_alloc_coherent(&dev->pdev->dev,
					  MTHCA_ICM_PAGE_SIZE, &page->mapping,
					  GFP_KERNEL);
	if (!page->db_rec) {
		ret = -ENOMEM;
		goto out;
	}

	ret = mthca_MAP_ICM_page(dev, page->mapping,
				 mthca_uarc_virt(dev, &dev->driver_uar, i));
	if (ret) {
		dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
				  page->db_rec, page->mapping);
		goto out;
	}

	bitmap_zero(page->used, MTHCA_DB_REC_PER_PAGE);

found:
	j = find_first_zero_bit(page->used, MTHCA_DB_REC_PER_PAGE);
	set_bit(j, page->used);

	if (group == 1)
		j = MTHCA_DB_REC_PER_PAGE - 1 - j;

	ret = i * MTHCA_DB_REC_PER_PAGE + j;

	page->db_rec[j] = cpu_to_be64((qn << 8) | (type << 5));

	*db = (__be32 *) &page->db_rec[j];

out:
	mutex_unlock(&dev->db_tab->mutex);

	return ret;
}

void mthca_free_db(struct mthca_dev *dev, int type, int db_index)
{
	int i, j;
	struct mthca_db_page *page;

	i = db_index / MTHCA_DB_REC_PER_PAGE;
	j = db_index % MTHCA_DB_REC_PER_PAGE;

	page = dev->db_tab->page + i;

	mutex_lock(&dev->db_tab->mutex);

	page->db_rec[j] = 0;
	if (i >= dev->db_tab->min_group2)
		j = MTHCA_DB_REC_PER_PAGE - 1 - j;
	clear_bit(j, page->used);

	if (bitmap_empty(page->used, MTHCA_DB_REC_PER_PAGE) &&
	    i >= dev->db_tab->max_group1 - 1) {
		mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, &dev->driver_uar, i), 1);

		dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
				  page->db_rec, page->mapping);
		page->db_rec = NULL;

		if (i == dev->db_tab->max_group1) {
			--dev->db_tab->max_group1;
			/* XXX may be able to unmap more pages now */
		}
		if (i == dev->db_tab->min_group2)
			++dev->db_tab->min_group2;
	}

	mutex_unlock(&dev->db_tab->mutex);
}

int mthca_init_db_tab(struct mthca_dev *dev)
{
	int i;

	if (!mthca_is_memfree(dev))
		return 0;

	dev->db_tab = kmalloc(sizeof *dev->db_tab, GFP_KERNEL);
	if (!dev->db_tab)
		return -ENOMEM;

	mutex_init(&dev->db_tab->mutex);

	dev->db_tab->npages     = dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE;
	dev->db_tab->max_group1 = 0;
	dev->db_tab->min_group2 = dev->db_tab->npages - 1;

	dev->db_tab->page = kmalloc_array(dev->db_tab->npages,
					  sizeof(*dev->db_tab->page),
					  GFP_KERNEL);
	if (!dev->db_tab->page) {
		kfree(dev->db_tab);
		return -ENOMEM;
	}

	for (i = 0; i < dev->db_tab->npages; ++i)
		dev->db_tab->page[i].db_rec = NULL;

	return 0;
}

void mthca_cleanup_db_tab(struct mthca_dev *dev)
{
	int i;

	if (!mthca_is_memfree(dev))
		return;

	/*
	 * Because we don't always free our UARC pages when they
	 * become empty to make mthca_free_db() simpler we need to
	 * make a sweep through the doorbell pages and free any
	 * leftover pages now.
	 */
	for (i = 0; i < dev->db_tab->npages; ++i) {
		if (!dev->db_tab->page[i].db_rec)
			continue;

		if (!bitmap_empty(dev->db_tab->page[i].used, MTHCA_DB_REC_PER_PAGE))
			mthca_warn(dev, "Kernel UARC page %d not empty\n", i);

		mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, &dev->driver_uar, i), 1);

		dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
				  dev->db_tab->page[i].db_rec,
				  dev->db_tab->page[i].mapping);
	}

	kfree(dev->db_tab->page);
	kfree(dev->db_tab);
}