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umem.c

/*
 * Copyright (c) 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Cisco Systems.  All rights reserved.
 * Copyright (c) 2005 Mellanox Technologies. 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.
 *
 * $Id: uverbs_mem.c 2743 2005-06-28 22:27:59Z roland $
 */

#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/sched.h>
#include <linux/hugetlb.h>

#include "uverbs.h"

#define IB_UMEM_MAX_PAGE_CHUNK                                    \
      ((PAGE_SIZE - offsetof(struct ib_umem_chunk, page_list)) /  \
       ((void *) &((struct ib_umem_chunk *) 0)->page_list[1] -    \
        (void *) &((struct ib_umem_chunk *) 0)->page_list[0]))

static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
      struct ib_umem_chunk *chunk, *tmp;
      int i;

      list_for_each_entry_safe(chunk, tmp, &umem->chunk_list, list) {
            ib_dma_unmap_sg(dev, chunk->page_list,
                        chunk->nents, DMA_BIDIRECTIONAL);
            for (i = 0; i < chunk->nents; ++i) {
                  struct page *page = sg_page(&chunk->page_list[i]);

                  if (umem->writable && dirty)
                        set_page_dirty_lock(page);
                  put_page(page);
            }

            kfree(chunk);
      }
}

/**
 * ib_umem_get - Pin and DMA map userspace memory.
 * @context: userspace context to pin memory for
 * @addr: userspace virtual address to start at
 * @size: length of region to pin
 * @access: IB_ACCESS_xxx flags for memory being pinned
 */
struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
                      size_t size, int access)
{
      struct ib_umem *umem;
      struct page **page_list;
      struct vm_area_struct **vma_list;
      struct ib_umem_chunk *chunk;
      unsigned long locked;
      unsigned long lock_limit;
      unsigned long cur_base;
      unsigned long npages;
      int ret;
      int off;
      int i;

      if (!can_do_mlock())
            return ERR_PTR(-EPERM);

      umem = kmalloc(sizeof *umem, GFP_KERNEL);
      if (!umem)
            return ERR_PTR(-ENOMEM);

      umem->context   = context;
      umem->length    = size;
      umem->offset    = addr & ~PAGE_MASK;
      umem->page_size = PAGE_SIZE;
      /*
       * We ask for writable memory if any access flags other than
       * "remote read" are set.  "Local write" and "remote write"
       * obviously require write access.  "Remote atomic" can do
       * things like fetch and add, which will modify memory, and
       * "MW bind" can change permissions by binding a window.
       */
      umem->writable  = !!(access & ~IB_ACCESS_REMOTE_READ);

      /* We assume the memory is from hugetlb until proved otherwise */
      umem->hugetlb   = 1;

      INIT_LIST_HEAD(&umem->chunk_list);

      page_list = (struct page **) __get_free_page(GFP_KERNEL);
      if (!page_list) {
            kfree(umem);
            return ERR_PTR(-ENOMEM);
      }

      /*
       * if we can't alloc the vma_list, it's not so bad;
       * just assume the memory is not hugetlb memory
       */
      vma_list = (struct vm_area_struct **) __get_free_page(GFP_KERNEL);
      if (!vma_list)
            umem->hugetlb = 0;

      npages = PAGE_ALIGN(size + umem->offset) >> PAGE_SHIFT;

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

      locked     = npages + current->mm->locked_vm;
      lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;

      if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
            ret = -ENOMEM;
            goto out;
      }

      cur_base = addr & PAGE_MASK;

      ret = 0;
      while (npages) {
            ret = get_user_pages(current, current->mm, cur_base,
                             min_t(int, npages,
                                 PAGE_SIZE / sizeof (struct page *)),
                             1, !umem->writable, page_list, vma_list);

            if (ret < 0)
                  goto out;

            cur_base += ret * PAGE_SIZE;
            npages   -= ret;

            off = 0;

            while (ret) {
                  chunk = kmalloc(sizeof *chunk + sizeof (struct scatterlist) *
                              min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK),
                              GFP_KERNEL);
                  if (!chunk) {
                        ret = -ENOMEM;
                        goto out;
                  }

                  chunk->nents = min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK);
                  sg_init_table(chunk->page_list, chunk->nents);
                  for (i = 0; i < chunk->nents; ++i) {
                        if (vma_list &&
                            !is_vm_hugetlb_page(vma_list[i + off]))
                              umem->hugetlb = 0;
                        sg_set_page(&chunk->page_list[i], page_list[i + off], PAGE_SIZE, 0);
                  }

                  chunk->nmap = ib_dma_map_sg(context->device,
                                        &chunk->page_list[0],
                                        chunk->nents,
                                        DMA_BIDIRECTIONAL);
                  if (chunk->nmap <= 0) {
                        for (i = 0; i < chunk->nents; ++i)
                              put_page(sg_page(&chunk->page_list[i]));
                        kfree(chunk);

                        ret = -ENOMEM;
                        goto out;
                  }

                  ret -= chunk->nents;
                  off += chunk->nents;
                  list_add_tail(&chunk->list, &umem->chunk_list);
            }

            ret = 0;
      }

out:
      if (ret < 0) {
            __ib_umem_release(context->device, umem, 0);
            kfree(umem);
      } else
            current->mm->locked_vm = locked;

      up_write(&current->mm->mmap_sem);
      if (vma_list)
            free_page((unsigned long) vma_list);
      free_page((unsigned long) page_list);

      return ret < 0 ? ERR_PTR(ret) : umem;
}
EXPORT_SYMBOL(ib_umem_get);

static void ib_umem_account(struct work_struct *work)
{
      struct ib_umem *umem = container_of(work, struct ib_umem, work);

      down_write(&umem->mm->mmap_sem);
      umem->mm->locked_vm -= umem->diff;
      up_write(&umem->mm->mmap_sem);
      mmput(umem->mm);
      kfree(umem);
}

/**
 * ib_umem_release - release memory pinned with ib_umem_get
 * @umem: umem struct to release
 */
void ib_umem_release(struct ib_umem *umem)
{
      struct ib_ucontext *context = umem->context;
      struct mm_struct *mm;
      unsigned long diff;

      __ib_umem_release(umem->context->device, umem, 1);

      mm = get_task_mm(current);
      if (!mm) {
            kfree(umem);
            return;
      }

      diff = PAGE_ALIGN(umem->length + umem->offset) >> PAGE_SHIFT;

      /*
       * We may be called with the mm's mmap_sem already held.  This
       * can happen when a userspace munmap() is the call that drops
       * the last reference to our file and calls our release
       * method.  If there are memory regions to destroy, we'll end
       * up here and not be able to take the mmap_sem.  In that case
       * we defer the vm_locked accounting to the system workqueue.
       */
      if (context->closing) {
            if (!down_write_trylock(&mm->mmap_sem)) {
                  INIT_WORK(&umem->work, ib_umem_account);
                  umem->mm   = mm;
                  umem->diff = diff;

                  schedule_work(&umem->work);
                  return;
            }
      } else
            down_write(&mm->mmap_sem);

      current->mm->locked_vm -= diff;
      up_write(&mm->mmap_sem);
      mmput(mm);
      kfree(umem);
}
EXPORT_SYMBOL(ib_umem_release);

int ib_umem_page_count(struct ib_umem *umem)
{
      struct ib_umem_chunk *chunk;
      int shift;
      int i;
      int n;

      shift = ilog2(umem->page_size);

      n = 0;
      list_for_each_entry(chunk, &umem->chunk_list, list)
            for (i = 0; i < chunk->nmap; ++i)
                  n += sg_dma_len(&chunk->page_list[i]) >> shift;

      return n;
}
EXPORT_SYMBOL(ib_umem_page_count);

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