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/mmu_context.h>
 9#include <linux/export.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#ifdef finish_arch_post_lock_switch
35	finish_arch_post_lock_switch();
36#endif
37
38	if (active_mm != mm)
39		mmdrop(active_mm);
40}
41EXPORT_SYMBOL_GPL(use_mm);
42
43/*
44 * unuse_mm
45 *	Reverses the effect of use_mm, i.e. releases the
46 *	specified mm context which was earlier taken on
47 *	by the calling kernel thread
48 *	(Note: this routine is intended to be called only
49 *	from a kernel thread context)
50 */
51void unuse_mm(struct mm_struct *mm)
52{
53	struct task_struct *tsk = current;
54
55	task_lock(tsk);
56	sync_mm_rss(mm);
57	tsk->mm = NULL;
58	/* active_mm is still 'mm' */
59	enter_lazy_tlb(mm, tsk);
60	task_unlock(tsk);
61}
62EXPORT_SYMBOL_GPL(unuse_mm);