ipath_user_pages.c

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/*
 * Copyright (c) 2006, 2007 QLogic Corporation. All rights reserved.
 * Copyright (c) 2003, 2004, 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/mm.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/sched.h>

#include "ipath_kernel.h"

static void __ipath_release_user_pages(struct page **p, size_t num_pages,
                   int dirty)
{
    size_t i;

    for (i = 0; i < num_pages; i++) {
        ipath_cdbg(MM, "%lu/%lu put_page %p\n", (unsigned long) i,
               (unsigned long) num_pages, p[i]);
        if (dirty)
            set_page_dirty_lock(p[i]);
        put_page(p[i]);
    }
}

/* call with current->mm->mmap_sem held */
static int __ipath_get_user_pages(unsigned long start_page, size_t num_pages,
                  struct page **p, struct vm_area_struct **vma)
{
    unsigned long lock_limit;
    size_t got;
    int ret;

    lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

    if (num_pages > lock_limit) {
        ret = -ENOMEM;
        goto bail;
    }

    ipath_cdbg(VERBOSE, "pin %lx pages from vaddr %lx\n",
           (unsigned long) num_pages, start_page);

    for (got = 0; got < num_pages; got += ret) {
        ret = get_user_pages(current, current->mm,
                     start_page + got * PAGE_SIZE,
                     num_pages - got, 1, 1,
                     p + got, vma);
        if (ret < 0)
            goto bail_release;
    }

    current->mm->pinned_vm += num_pages;

    ret = 0;
    goto bail;

bail_release:
    __ipath_release_user_pages(p, got, 0);
bail:
    return ret;
}

dma_addr_t ipath_map_page(struct pci_dev *hwdev, struct page *page,
    unsigned long offset, size_t size, int direction)
{
    dma_addr_t phys;

    phys = pci_map_page(hwdev, page, offset, size, direction);

    if (phys == 0) {
        pci_unmap_page(hwdev, phys, size, direction);
        phys = pci_map_page(hwdev, page, offset, size, direction);
        /*
         * FIXME: If we get 0 again, we should keep this page,
         * map another, then free the 0 page.
         */
    }

    return phys;
}

dma_addr_t ipath_map_single(struct pci_dev *hwdev, void *ptr, size_t size,
    int direction)
{
    dma_addr_t phys;

    phys = pci_map_single(hwdev, ptr, size, direction);

    if (phys == 0) {
        pci_unmap_single(hwdev, phys, size, direction);
        phys = pci_map_single(hwdev, ptr, size, direction);
        /*
         * FIXME: If we get 0 again, we should keep this page,
         * map another, then free the 0 page.
         */
    }

    return phys;
}

int ipath_get_user_pages(unsigned long start_page, size_t num_pages,
             struct page **p)
{
    int ret;

    down_write(&current->mm->mmap_sem);

    ret = __ipath_get_user_pages(start_page, num_pages, p, NULL);

    up_write(&current->mm->mmap_sem);

    return ret;
}

void ipath_release_user_pages(struct page **p, size_t num_pages)
{
    down_write(&current->mm->mmap_sem);

    __ipath_release_user_pages(p, num_pages, 1);

    current->mm->pinned_vm -= num_pages;

    up_write(&current->mm->mmap_sem);
}

struct ipath_user_pages_work {
    struct work_struct work;
    struct mm_struct *mm;
    unsigned long num_pages;
};

static void user_pages_account(struct work_struct *_work)
{
    struct ipath_user_pages_work *work =
        container_of(_work, struct ipath_user_pages_work, work);

    down_write(&work->mm->mmap_sem);
    work->mm->pinned_vm -= work->num_pages;
    up_write(&work->mm->mmap_sem);
    mmput(work->mm);
    kfree(work);
}

void ipath_release_user_pages_on_close(struct page **p, size_t num_pages)
{
    struct ipath_user_pages_work *work;
    struct mm_struct *mm;

    __ipath_release_user_pages(p, num_pages, 1);

    mm = get_task_mm(current);
    if (!mm)
        return;

    work = kmalloc(sizeof(*work), GFP_KERNEL);
    if (!work)
        goto bail_mm;

    INIT_WORK(&work->work, user_pages_account);
    work->mm = mm;
    work->num_pages = num_pages;

    queue_work(ib_wq, &work->work);
    return;

bail_mm:
    mmput(mm);
    return;
}