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mm: move use_mm/unuse_mm from aio.c to mm/

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Anyone who wants to do copy to/from user from a kernel thread, needs
use_mm (like what fs/aio has).  Move that into mm/, to make reusing and
exporting easier down the line, and make aio use it.  Next intended user,
besides aio, will be vhost-net.

Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michael S. Tsirkin 2009-09-21 17:03:51 -07:00 committed by Linus Torvalds
parent 425fbf047c
commit 3d2d827f5c
4 changed files with 66 additions and 47 deletions
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47
fs/aio.c
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@ -24,6 +24,7 @@
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/mmu_context.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/aio.h>
@ -34,7 +35,6 @@
#include <asm/kmap_types.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#if DEBUG > 1
#define dprintk printk
@ -594,51 +594,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
return ret;
}
/*
* use_mm
* Makes the calling kernel thread take on the specified
* mm context.
* Called by the retry thread execute retries within the
* iocb issuer's mm context, so that copy_from/to_user
* operations work seamlessly for aio.
* (Note: this routine is intended to be called only
* from a kernel thread context)
*/
static void use_mm(struct mm_struct *mm)
{
struct mm_struct *active_mm;
struct task_struct *tsk = current;
task_lock(tsk);
active_mm = tsk->active_mm;
atomic_inc(&mm->mm_count);
tsk->mm = mm;
tsk->active_mm = mm;
switch_mm(active_mm, mm, tsk);
task_unlock(tsk);
mmdrop(active_mm);
}
/*
* unuse_mm
* Reverses the effect of use_mm, i.e. releases the
* specified mm context which was earlier taken on
* by the calling kernel thread
* (Note: this routine is intended to be called only
* from a kernel thread context)
*/
static void unuse_mm(struct mm_struct *mm)
{
struct task_struct *tsk = current;
task_lock(tsk);
tsk->mm = NULL;
/* active_mm is still 'mm' */
enter_lazy_tlb(mm, tsk);
task_unlock(tsk);
}
/*
* Queue up a kiocb to be retried. Assumes that the kiocb
* has already been marked as kicked, and places it on

9
include/linux/mmu_context.h Normal file
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@ -0,0 +1,9 @@
#ifndef _LINUX_MMU_CONTEXT_H
#define _LINUX_MMU_CONTEXT_H
struct mm_struct;
void use_mm(struct mm_struct *mm);
void unuse_mm(struct mm_struct *mm);
#endif

2
mm/Makefile
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@ -11,7 +11,7 @@ obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
maccess.o page_alloc.o page-writeback.o \
readahead.o swap.o truncate.o vmscan.o shmem.o \
prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
page_isolation.o mm_init.o $(mmu-y)
page_isolation.o mm_init.o mmu_context.o $(mmu-y)
obj-y += init-mm.o
obj-$(CONFIG_PROC_PAGE_MONITOR) += pagewalk.o

55
mm/mmu_context.c Normal file
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@ -0,0 +1,55 @@
/* Copyright (C) 2009 Red Hat, Inc.
*
* See ../COPYING for licensing terms.
*/
#include <linux/mm.h>
#include <linux/mmu_context.h>
#include <linux/sched.h>
#include <asm/mmu_context.h>
/*
* use_mm
* Makes the calling kernel thread take on the specified
* mm context.
* Called by the retry thread execute retries within the
* iocb issuer's mm context, so that copy_from/to_user
* operations work seamlessly for aio.
* (Note: this routine is intended to be called only
* from a kernel thread context)
*/
void use_mm(struct mm_struct *mm)
{
struct mm_struct *active_mm;
struct task_struct *tsk = current;
task_lock(tsk);
active_mm = tsk->active_mm;
atomic_inc(&mm->mm_count);
tsk->mm = mm;
tsk->active_mm = mm;
switch_mm(active_mm, mm, tsk);
task_unlock(tsk);
mmdrop(active_mm);
}
/*
* unuse_mm
* Reverses the effect of use_mm, i.e. releases the
* specified mm context which was earlier taken on
* by the calling kernel thread
* (Note: this routine is intended to be called only
* from a kernel thread context)
*/
void unuse_mm(struct mm_struct *mm)
{
struct task_struct *tsk = current;
task_lock(tsk);
tsk->mm = NULL;
/* active_mm is still 'mm' */
enter_lazy_tlb(mm, tsk);
task_unlock(tsk);
}