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/sched.h>
   8 #include <linux/sched/mm.h>
   9 #include <linux/sched/task.h>
  10 #include <linux/mmu_context.h>
  11 #include <linux/export.h>
  12
  13 #include <asm/mmu_context.h>
  14
  15 /*
  16  * use_mm
  17  *      Makes the calling kernel thread take on the specified
  18  *      mm context.
  19  *      (Note: this routine is intended to be called only
  20  *      from a kernel thread context)
  21  */
  22 void 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                 mmgrab(mm);
  31                 tsk->active_mm = mm;
  32         }
  33         tsk->mm = mm;
  34         switch_mm(active_mm, mm, tsk);
  35         task_unlock(tsk);
  36 #ifdef finish_arch_post_lock_switch
  37         finish_arch_post_lock_switch();
  38 #endif
  39
  40         if (active_mm != mm)
  41                 mmdrop(active_mm);
  42 }
  43 EXPORT_SYMBOL_GPL(use_mm);
  44
  45 /*
  46  * unuse_mm
  47  *      Reverses the effect of use_mm, i.e. releases the
  48  *      specified mm context which was earlier taken on
  49  *      by the calling kernel thread
  50  *      (Note: this routine is intended to be called only
  51  *      from a kernel thread context)
  52  */
  53 void unuse_mm(struct mm_struct *mm)
  54 {
  55         struct task_struct *tsk = current;
  56
  57         task_lock(tsk);
  58         sync_mm_rss(mm);
  59         tsk->mm = NULL;
  60         /* active_mm is still 'mm' */
  61         enter_lazy_tlb(mm, tsk);
  62         task_unlock(tsk);
  63 }
  64 EXPORT_SYMBOL_GPL(unuse_mm);