diff mbox

[PATCHv2,1/2] mm: export use_mm/unuse_mm to modules

Message ID 20090811212752.GB26309@redhat.com
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Michael S. Tsirkin Aug. 11, 2009, 9:27 p.m. UTC 
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@redhat.com>
---
 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

Comments

Andrew Morton Aug. 11, 2009, 10:10 p.m. UTC | #1 
On Wed, 12 Aug 2009 00:27:52 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> 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.

OK by me.  Please include this change in the virtio patchset.  Which I
shall cheerfully not be looking at :)

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Michael S. Tsirkin Sept. 17, 2009, 5:38 a.m. UTC | #2 
Hi Andrew,
On Tue, Aug 11, 2009 at 03:10:10PM -0700, Andrew Morton wrote:
> On Wed, 12 Aug 2009 00:27:52 +0300
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > 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.
> 
> OK by me.  Please include this change in the virtio patchset.  Which I
> shall cheerfully not be looking at :)

The virtio patches are somewhat delayed as we are ironing out the
kernel/user interface with Rusty. Can the patch moving use_mm to mm/ be
applied without exporting to modules for now? This will make it easier
for virtio which will only have to patch in the EXPORT line.

I also have a small patch optimizing atomic usage in use_mm (which I did for
virtio) and it's easier to apply it if the code is in the new place.

If ok, pls let me know and I'll post the patch without the EXPORT line.
Andrew Morton Sept. 17, 2009, 5:43 a.m. UTC | #3 
On Thu, 17 Sep 2009 08:38:18 +0300 "Michael S. Tsirkin" <mst@redhat.com> wrote:

> Hi Andrew,
> On Tue, Aug 11, 2009 at 03:10:10PM -0700, Andrew Morton wrote:
> > On Wed, 12 Aug 2009 00:27:52 +0300
> > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > 
> > > 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.
> > 
> > OK by me.  Please include this change in the virtio patchset.  Which I
> > shall cheerfully not be looking at :)
> 
> The virtio patches are somewhat delayed as we are ironing out the
> kernel/user interface with Rusty. Can the patch moving use_mm to mm/ be
> applied without exporting to modules for now? This will make it easier
> for virtio which will only have to patch in the EXPORT line.

That was 10,000 patches ago.

> I also have a small patch optimizing atomic usage in use_mm (which I did for
> virtio) and it's easier to apply it if the code is in the new place.
> 
> If ok, pls let me know and I'll post the patch without the EXPORT line.

Please just send them all out.
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diff mbox

Patch

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);