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ipath_user_pages.c

/*
 * 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 "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 __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 = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >>
            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->locked_vm += num_pages;

      ret = 0;
      goto bail;

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

/**
 * ipath_map_page - a safety wrapper around pci_map_page()
 *
 * A dma_addr of all 0's is interpreted by the chip as "disabled".
 * Unfortunately, it can also be a valid dma_addr returned on some
 * architectures.
 *
 * The powerpc iommu assigns dma_addrs in ascending order, so we don't
 * have to bother with retries or mapping a dummy page to insure we
 * don't just get the same mapping again.
 *
 * I'm sure we won't be so lucky with other iommu's, so FIXME.
 */
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;
}

/**
 * ipath_map_single - a safety wrapper around pci_map_single()
 *
 * Same idea as ipath_map_page().
 */
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;
}

/**
 * ipath_get_user_pages - lock user pages into memory
 * @start_page: the start page
 * @num_pages: the number of pages
 * @p: the output page structures
 *
 * This function takes a given start page (page aligned user virtual
 * address) and pins it and the following specified number of pages.  For
 * now, num_pages is always 1, but that will probably change at some point
 * (because caller is doing expected sends on a single virtually contiguous
 * buffer, so we can do all pages at once).
 */
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 = __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->locked_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->locked_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)
            goto bail;

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

      goto bail;

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

bail_mm:
      mmput(mm);
bail:
      return;
}

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