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Message-ID: <20090811111903.GA3809@redhat.com>
Date: Tue, 11 Aug 2009 14:19:04 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: netdev@...r.kernel.org, virtualization@...ts.linux-foundation.org,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org, mingo@...e.hu,
linux-mm@...ck.org, akpm@...ux-foundation.org
Subject: Re: [PATCH 1/2] export cpu_tlbstate to modules
Subject: [PATCH] mm: export use_mm/unuse_mm to modules
vhost net module wants to do copy to/from user from a kernel thread,
which needs use_mm (like what fs/aio has). Move that into mm/ and
export to modules.
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
On Mon, Aug 10, 2009 at 03:24:50PM -0700, H. Peter Anvin wrote:
> On 08/10/2009 03:06 PM, Michael S. Tsirkin wrote:
> >> Wouldn't it be a *lot* better to move use_mm() from fs/aio.c into common
> >> code, and export that instead?
> >
> > That's easy too. What would a good place for it be?
>
> Somewhere in mm/, presumably. When in doubt, make it a new file...
>
> -hpa
Like this? Ack?
fs/aio.c | 47 +----------------------------------
include/linux/mmu_context.h | 9 ++++++
mm/Makefile | 2 +-
mm/mmu_context.c | 58 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 69 insertions(+), 47 deletions(-)
create mode 100644 include/linux/mmu_context.h
create mode 100644 mm/mmu_context.c
diff --git a/fs/aio.c b/fs/aio.c
index d065b2c..fc21c23 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -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
@@ -595,51 +595,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
}
/*
- * 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
* the retry run list for the corresponding ioctx, if it
diff --git a/include/linux/mmu_context.h b/include/linux/mmu_context.h
new file mode 100644
index 0000000..70fffeb
--- /dev/null
+++ b/include/linux/mmu_context.h
@@ -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
diff --git a/mm/Makefile b/mm/Makefile
index 5e0bd64..46c3892 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -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 pdflush.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
diff --git a/mm/mmu_context.c b/mm/mmu_context.c
new file mode 100644
index 0000000..9989c2f
--- /dev/null
+++ b/mm/mmu_context.c
@@ -0,0 +1,58 @@
+/* Copyright (C) 2009 Red Hat, Inc.
+ *
+ * See ../COPYING for licensing terms.
+ */
+
+#include <linux/mm.h>
+#include <linux/mmu_context.h>
+#include <linux/module.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);
+}
+EXPORT_SYMBOL_GPL(use_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);
+}
+EXPORT_SYMBOL_GPL(unuse_mm);
--
1.6.2.5
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