blob: ded9081f40219d888e48e41d4b665a712a188d28 [file] [log] [blame]
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -07001/* 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/sched.h>
9
10#include <asm/mmu_context.h>
11
12/*
13 * use_mm
14 * Makes the calling kernel thread take on the specified
15 * mm context.
16 * Called by the retry thread execute retries within the
17 * iocb issuer's mm context, so that copy_from/to_user
18 * operations work seamlessly for aio.
19 * (Note: this routine is intended to be called only
20 * from a kernel thread context)
21 */
22void 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;
Michael S. Tsirkinf68e1482009-09-21 17:03:52 -070029 if (active_mm != mm) {
30 atomic_inc(&mm->mm_count);
31 tsk->active_mm = mm;
32 }
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -070033 tsk->mm = mm;
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -070034 switch_mm(active_mm, mm, tsk);
35 task_unlock(tsk);
36
Michael S. Tsirkinf68e1482009-09-21 17:03:52 -070037 if (active_mm != mm)
38 mmdrop(active_mm);
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -070039}
40
41/*
42 * unuse_mm
43 * Reverses the effect of use_mm, i.e. releases the
44 * specified mm context which was earlier taken on
45 * by the calling kernel thread
46 * (Note: this routine is intended to be called only
47 * from a kernel thread context)
48 */
49void unuse_mm(struct mm_struct *mm)
50{
51 struct task_struct *tsk = current;
52
53 task_lock(tsk);
54 tsk->mm = NULL;
55 /* active_mm is still 'mm' */
56 enter_lazy_tlb(mm, tsk);
57 task_unlock(tsk);
58}