qib_mmap.c

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/*
 * Copyright (c) 2006, 2007, 2008, 2009 QLogic Corporation. 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/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <asm/pgtable.h>

#include "qib_verbs.h"

void qib_release_mmap_info(struct kref *ref)
{
    struct qib_mmap_info *ip =
        container_of(ref, struct qib_mmap_info, ref);
    struct qib_ibdev *dev = to_idev(ip->context->device);

    spin_lock_irq(&dev->pending_lock);
    list_del(&ip->pending_mmaps);
    spin_unlock_irq(&dev->pending_lock);

    vfree(ip->obj);
    kfree(ip);
}

/*
 * open and close keep track of how many times the CQ is mapped,
 * to avoid releasing it.
 */
static void qib_vma_open(struct vm_area_struct *vma)
{
    struct qib_mmap_info *ip = vma->vm_private_data;

    kref_get(&ip->ref);
}

static void qib_vma_close(struct vm_area_struct *vma)
{
    struct qib_mmap_info *ip = vma->vm_private_data;

    kref_put(&ip->ref, qib_release_mmap_info);
}

static struct vm_operations_struct qib_vm_ops = {
    .open =     qib_vma_open,
    .close =    qib_vma_close,
};

int qib_mmap(struct ib_ucontext *context, struct vm_area_struct *vma)
{
    struct qib_ibdev *dev = to_idev(context->device);
    unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
    unsigned long size = vma->vm_end - vma->vm_start;
    struct qib_mmap_info *ip, *pp;
    int ret = -EINVAL;

    /*
     * Search the device's list of objects waiting for a mmap call.
     * Normally, this list is very short since a call to create a
     * CQ, QP, or SRQ is soon followed by a call to mmap().
     */
    spin_lock_irq(&dev->pending_lock);
    list_for_each_entry_safe(ip, pp, &dev->pending_mmaps,
                 pending_mmaps) {
        /* Only the creator is allowed to mmap the object */
        if (context != ip->context || (__u64) offset != ip->offset)
            continue;
        /* Don't allow a mmap larger than the object. */
        if (size > ip->size)
            break;

        list_del_init(&ip->pending_mmaps);
        spin_unlock_irq(&dev->pending_lock);

        ret = remap_vmalloc_range(vma, ip->obj, 0);
        if (ret)
            goto done;
        vma->vm_ops = &qib_vm_ops;
        vma->vm_private_data = ip;
        qib_vma_open(vma);
        goto done;
    }
    spin_unlock_irq(&dev->pending_lock);
done:
    return ret;
}

/*
 * Allocate information for qib_mmap
 */
struct qib_mmap_info *qib_create_mmap_info(struct qib_ibdev *dev,
                       u32 size,
                       struct ib_ucontext *context,
                       void *obj) {
    struct qib_mmap_info *ip;

    ip = kmalloc(sizeof *ip, GFP_KERNEL);
    if (!ip)
        goto bail;

    size = PAGE_ALIGN(size);

    spin_lock_irq(&dev->mmap_offset_lock);
    if (dev->mmap_offset == 0)
        dev->mmap_offset = PAGE_SIZE;
    ip->offset = dev->mmap_offset;
    dev->mmap_offset += size;
    spin_unlock_irq(&dev->mmap_offset_lock);

    INIT_LIST_HEAD(&ip->pending_mmaps);
    ip->size = size;
    ip->context = context;
    ip->obj = obj;
    kref_init(&ip->ref);

bail:
    return ip;
}

void qib_update_mmap_info(struct qib_ibdev *dev, struct qib_mmap_info *ip,
              u32 size, void *obj)
{
    size = PAGE_ALIGN(size);

    spin_lock_irq(&dev->mmap_offset_lock);
    if (dev->mmap_offset == 0)
        dev->mmap_offset = PAGE_SIZE;
    ip->offset = dev->mmap_offset;
    dev->mmap_offset += size;
    spin_unlock_irq(&dev->mmap_offset_lock);

    ip->size = size;
    ip->obj = obj;
}