From b8e3537772b780c28475e49275aff04bcb973e5c Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Thu, 6 Jun 2013 15:20:39 +0300
Subject: [PATCH] --- yaml --- r: 377013 b: refs/heads/master c:
 05c05351943cc03bf5c77e86953b24ae6fb21368 h: refs/heads/master i:   377011:
 21da4da23c0459a0a131da8b8420fc65db36e538 v: v3

---
 [refs]                      | 2 +-
 trunk/drivers/vhost/net.c   | 4 ++++
 trunk/drivers/vhost/vhost.c | 8 +++++++-
 trunk/drivers/vhost/vhost.h | 1 +
 4 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index cb30d1255b05..c39220760c1c 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c2020be3c35ab230b4ee046c262ddab3e0d3aab4
+refs/heads/master: 05c05351943cc03bf5c77e86953b24ae6fb21368
diff --git a/trunk/drivers/vhost/net.c b/trunk/drivers/vhost/net.c
index b07d96b8c0d1..8cf5aece8c84 100644
--- a/trunk/drivers/vhost/net.c
+++ b/trunk/drivers/vhost/net.c
@@ -1054,6 +1054,10 @@ static long vhost_net_set_owner(struct vhost_net *n)
 	int r;
 
 	mutex_lock(&n->dev.mutex);
+	if (vhost_dev_has_owner(&n->dev)) {
+		r = -EBUSY;
+		goto out;
+	}
 	r = vhost_net_set_ubuf_info(n);
 	if (r)
 		goto out;
diff --git a/trunk/drivers/vhost/vhost.c b/trunk/drivers/vhost/vhost.c
index beee7f5787e6..60aa5ad09a2f 100644
--- a/trunk/drivers/vhost/vhost.c
+++ b/trunk/drivers/vhost/vhost.c
@@ -343,6 +343,12 @@ static int vhost_attach_cgroups(struct vhost_dev *dev)
 	return attach.ret;
 }
 
+/* Caller should have device mutex */
+bool vhost_dev_has_owner(struct vhost_dev *dev)
+{
+	return dev->mm;
+}
+
 /* Caller should have device mutex */
 long vhost_dev_set_owner(struct vhost_dev *dev)
 {
@@ -350,7 +356,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
 	int err;
 
 	/* Is there an owner already? */
-	if (dev->mm) {
+	if (vhost_dev_has_owner(dev)) {
 		err = -EBUSY;
 		goto err_mm;
 	}
diff --git a/trunk/drivers/vhost/vhost.h b/trunk/drivers/vhost/vhost.h
index a7ad63592987..64adcf99ff33 100644
--- a/trunk/drivers/vhost/vhost.h
+++ b/trunk/drivers/vhost/vhost.h
@@ -133,6 +133,7 @@ struct vhost_dev {
 
 long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);
 long vhost_dev_set_owner(struct vhost_dev *dev);
+bool vhost_dev_has_owner(struct vhost_dev *dev);
 long vhost_dev_check_owner(struct vhost_dev *);
 struct vhost_memory *vhost_dev_reset_owner_prepare(void);
 void vhost_dev_reset_owner(struct vhost_dev *, struct vhost_memory *);