Cross-Referenced Linux and Device Driver Code

   /*
    * 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;
 }