blob: 0777654147c9d0e3fd0b676771dc5052bcab9455 [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>
Michael S. Tsirkin5da779c2010-01-14 06:17:18 +00008#include <linux/module.h>
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -07009#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 * Called by the retry thread execute retries within the
18 * iocb issuer's mm context, so that copy_from/to_user
19 * operations work seamlessly for aio.
20 * (Note: this routine is intended to be called only
21 * from a kernel thread context)
22 */
23void use_mm(struct mm_struct *mm)
24{
25 struct mm_struct *active_mm;
26 struct task_struct *tsk = current;
27
28 task_lock(tsk);
29 active_mm = tsk->active_mm;
Michael S. Tsirkinf68e1482009-09-21 17:03:52 -070030 if (active_mm != mm) {
31 atomic_inc(&mm->mm_count);
32 tsk->active_mm = mm;
33 }
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -070034 tsk->mm = mm;
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -070035 switch_mm(active_mm, mm, tsk);
36 task_unlock(tsk);
37
Michael S. Tsirkinf68e1482009-09-21 17:03:52 -070038 if (active_mm != mm)
39 mmdrop(active_mm);
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -070040}
Michael S. Tsirkin5da779c2010-01-14 06:17:18 +000041EXPORT_SYMBOL_GPL(use_mm);
Michael S. Tsirkin3d2d8272009-09-21 17:03:51 -070042
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 tsk->mm = NULL;
57 /* active_mm is still 'mm' */
58 enter_lazy_tlb(mm, tsk);
59 task_unlock(tsk);
60}
Michael S. Tsirkin5da779c2010-01-14 06:17:18 +000061EXPORT_SYMBOL_GPL(unuse_mm);