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Commit 3d2d827f authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Linus Torvalds
Browse files

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



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: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 425fbf04

fs/aio.c

+1 −46
Original line number Diff line number Diff line
@@ -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

include/linux/mmu_context.h

0 → 100644
+9 −0
Original line number Diff line number Diff line 
#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

mm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

mm/mmu_context.c

0 → 100644
+55 −0
Original line number Diff line number Diff line 
/* 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);

}