Root/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 */
20void 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}
38EXPORT_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 */
48void 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}
59EXPORT_SYMBOL_GPL(unuse_mm);
60

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