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/mmu_context.h>
  10 #include <linux/export.h>
  11
  12 #include <asm/mmu_context.h>
  13
  14 /*
  15  * use_mm
  16  *      Makes the calling kernel thread take on the specified
  17  *      mm context.
  18  *      (Note: this routine is intended to be called only
  19  *      from a kernel thread context)
  20  */
  21 void use_mm(struct mm_struct *mm)
  22 {
  23         struct mm_struct *active_mm;
  24         struct task_struct *tsk = current;
  25
  26         task_lock(tsk);
  27         active_mm = tsk->active_mm;
  28         if (active_mm != mm) {
  29                 mmgrab(mm);
  30                 tsk->active_mm = mm;
  31         }
  32         tsk->mm = mm;
  33         switch_mm(active_mm, mm, tsk);
  34         task_unlock(tsk);
  35 #ifdef finish_arch_post_lock_switch
  36         finish_arch_post_lock_switch();
  37 #endif
  38
  39         if (active_mm != mm)
  40                 mmdrop(active_mm);
  41 }
  42 EXPORT_SYMBOL_GPL(use_mm);
  43
  44 /*
  45  * unuse_mm
  46  *      Reverses the effect of use_mm, i.e. releases the
  47  *      specified mm context which was earlier taken on
  48  *      by the calling kernel thread
  49  *      (Note: this routine is intended to be called only
  50  *      from a kernel thread context)
  51  */
  52 void unuse_mm(struct mm_struct *mm)
  53 {
  54         struct task_struct *tsk = current;
  55
  56         task_lock(tsk);
  57         sync_mm_rss(mm);
  58         tsk->mm = NULL;
  59         /* active_mm is still 'mm' */
  60         enter_lazy_tlb(mm, tsk);
  61         task_unlock(tsk);
  62 }
  63 EXPORT_SYMBOL_GPL(unuse_mm);