doorbell.c

Go to the documentation of this file.

/*
 * Copyright (c) 2007 Cisco Systems, 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/slab.h>

#include "mlx4_ib.h"

struct mlx4_ib_user_db_page {
    struct list_head    list;
    struct ib_umem         *umem;
    unsigned long       user_virt;
    int         refcnt;
};

int mlx4_ib_db_map_user(struct mlx4_ib_ucontext *context, unsigned long virt,
            struct mlx4_db *db)
{
    struct mlx4_ib_user_db_page *page;
    struct ib_umem_chunk *chunk;
    int err = 0;

    mutex_lock(&context->db_page_mutex);

    list_for_each_entry(page, &context->db_page_list, list)
        if (page->user_virt == (virt & PAGE_MASK))
            goto found;

    page = kmalloc(sizeof *page, GFP_KERNEL);
    if (!page) {
        err = -ENOMEM;
        goto out;
    }

    page->user_virt = (virt & PAGE_MASK);
    page->refcnt    = 0;
    page->umem      = ib_umem_get(&context->ibucontext, virt & PAGE_MASK,
                      PAGE_SIZE, 0, 0);
    if (IS_ERR(page->umem)) {
        err = PTR_ERR(page->umem);
        kfree(page);
        goto out;
    }

    list_add(&page->list, &context->db_page_list);

found:
    chunk = list_entry(page->umem->chunk_list.next, struct ib_umem_chunk, list);
    db->dma     = sg_dma_address(chunk->page_list) + (virt & ~PAGE_MASK);
    db->u.user_page = page;
    ++page->refcnt;

out:
    mutex_unlock(&context->db_page_mutex);

    return err;
}

void mlx4_ib_db_unmap_user(struct mlx4_ib_ucontext *context, struct mlx4_db *db)
{
    mutex_lock(&context->db_page_mutex);

    if (!--db->u.user_page->refcnt) {
        list_del(&db->u.user_page->list);
        ib_umem_release(db->u.user_page->umem);
        kfree(db->u.user_page);
    }

    mutex_unlock(&context->db_page_mutex);
}