mm/mmu_context.c

   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/export.h>
   9 #include <linux/sched.h>
  10
  11 #include <asm/mmu_context.h>
  12
  13 /*
  14  * use_mm
  15  *      Makes the calling kernel thread take on the specified
  16  *      mm context.
  17  *      (Note: this routine is intended to be called only
  18  *      from a kernel thread context)
  19  */
  20 void use_mm(struct mm_struct *mm)
  21 {
  22         struct mm_struct *active_mm;
  23         struct task_struct *tsk = current;
  24
  25         task_lock(tsk);
  26         active_mm = tsk->active_mm;
  27         if (active_mm != mm) {
  28                 atomic_inc(&mm->mm_count);
  29                 tsk->active_mm = mm;
  30         }
  31         tsk->mm = mm;
  32         switch_mm(active_mm, mm, tsk);
  33         task_unlock(tsk);
  34
  35         if (active_mm != mm)
  36                 mmdrop(active_mm);
  37 }
  38 EXPORT_SYMBOL_GPL(use_mm);
  39
  40 /*
  41  * unuse_mm
  42  *      Reverses the effect of use_mm, i.e. releases the
  43  *      specified mm context which was earlier taken on
  44  *      by the calling kernel thread
  45  *      (Note: this routine is intended to be called only
  46  *      from a kernel thread context)
  47  */
  48 void unuse_mm(struct mm_struct *mm)
  49 {
  50         struct task_struct *tsk = current;
  51
  52         task_lock(tsk);
  53         sync_mm_rss(mm);
  54         tsk->mm = NULL;
  55         /* active_mm is still 'mm' */
  56         enter_lazy_tlb(mm, tsk);
  57         task_unlock(tsk);
  58 }
  59 EXPORT_SYMBOL_GPL(unuse_mm);