LXR linux/mm/mmu

   1/* Copyright (C) 2009 Red Hat, Inc.
   2 *
   3 * See ../COPYING for licensing terms.
   4 */
   5
   6#include <linux/mm.h>
   7#include <linux/mmu_context.h>
   8#include <linux/sched.h>
   9
  10#include <asm/mmu_context.h>
  11
  12/*
  13 * use_mm
  14 *      Makes the calling kernel thread take on the specified
  15 *      mm context.
  16 *      Called by the retry thread execute retries within the
  17 *      iocb issuer's mm context, so that copy_from/to_user
  18 *      operations work seamlessly for aio.
  19 *      (Note: this routine is intended to be called only
  20 *      from a kernel thread context)
  21 */
  22void use_mm(struct mm_struct *mm)
  23{
  24        struct mm_struct *active_mm;
  25        struct task_struct *tsk = current;
  26
  27        task_lock(tsk);
  28        active_mm = tsk->active_mm;
  29        if (active_mm != mm) {
  30                atomic_inc(&mm->mm_count);
  31                tsk->active_mm = mm;
  32        }
  33        tsk->mm = mm;
  34        switch_mm(active_mm, mm, tsk);
  35        task_unlock(tsk);
  36
  37        if (active_mm != mm)
  38                mmdrop(active_mm);
  39}
  40
  41/*
  42 * unuse_mm
  43 *      Reverses the effect of use_mm, i.e. releases the
  44 *      specified mm context which was earlier taken on
  45 *      by the calling kernel thread
  46 *      (Note: this routine is intended to be called only
  47 *      from a kernel thread context)
  48 */
  49void unuse_mm(struct mm_struct *mm)
  50{
  51        struct task_struct *tsk = current;
  52
  53        task_lock(tsk);
  54        tsk->mm = NULL;
  55        /* active_mm is still 'mm' */
  56        enter_lazy_tlb(mm, tsk);
  57        task_unlock(tsk);
  58}
  59