[RFC PATCH 06/10] vhost: extract ioctl locking to common code

[Vincent Whitchurch]

Extract the mutex locking for the vhost ioctl into common code.  This
will allow the common code to easily add some extra handling required
for adding a kernel API to control vhost.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
---
 drivers/vhost/common.c |  7 ++++++-
 drivers/vhost/net.c    | 14 +-------------
 drivers/vhost/vhost.c  | 10 ++++++++--
 drivers/vhost/vhost.h  |  1 +
 drivers/vhost/vsock.c  | 12 ------------
 5 files changed, 16 insertions(+), 28 deletions(-)

diff --git a/drivers/vhost/common.c b/drivers/vhost/common.c
index 27d4672b15d3..a5722ad65e24 100644
--- a/drivers/vhost/common.c
+++ b/drivers/vhost/common.c
@@ -60,8 +60,13 @@ static long vhost_ioctl(struct file *file, unsigned int ioctl, unsigned long arg
 {
 	struct vhost_dev *dev = file->private_data;
 	struct vhost *vhost = dev->vhost;
+	long ret;
 
-	return vhost->ops->ioctl(dev, ioctl, arg);
+	mutex_lock(&dev->mutex);
+	ret = vhost->ops->ioctl(dev, ioctl, arg);
+	mutex_unlock(&dev->mutex);
+
+	return ret;
 }
 
 static ssize_t vhost_read_iter(struct kiocb *iocb, struct iov_iter *to)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 8910d9e2a74e..b5590b7862a9 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1505,7 +1505,6 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 	struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
 	int r;
 
-	mutex_lock(&n->dev.mutex);
 	r = vhost_dev_check_owner(&n->dev);
 	if (r)
 		goto err;
@@ -1573,7 +1572,6 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 		sockfd_put(oldsock);
 	}
 
-	mutex_unlock(&n->dev.mutex);
 	return 0;
 
 err_used:
@@ -1587,7 +1585,6 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 err_vq:
 	mutex_unlock(&vq->mutex);
 err:
-	mutex_unlock(&n->dev.mutex);
 	return r;
 }
 
@@ -1598,7 +1595,6 @@ static long vhost_net_reset_owner(struct vhost_net *n)
 	long err;
 	struct vhost_iotlb *umem;
 
-	mutex_lock(&n->dev.mutex);
 	err = vhost_dev_check_owner(&n->dev);
 	if (err)
 		goto done;
@@ -1613,7 +1609,6 @@ static long vhost_net_reset_owner(struct vhost_net *n)
 	vhost_dev_reset_owner(&n->dev, umem);
 	vhost_net_vq_reset(n);
 done:
-	mutex_unlock(&n->dev.mutex);
 	if (tx_sock)
 		sockfd_put(tx_sock);
 	if (rx_sock)
@@ -1639,7 +1634,6 @@ static int vhost_net_set_features(struct vhost_net *n, u64 features)
 		vhost_hlen = 0;
 		sock_hlen = hdr_len;
 	}
-	mutex_lock(&n->dev.mutex);
 	if ((features & (1 << VHOST_F_LOG_ALL)) &&
 	    !vhost_log_access_ok(&n->dev))
 		goto out_unlock;
@@ -1656,11 +1650,9 @@ static int vhost_net_set_features(struct vhost_net *n, u64 features)
 		n->vqs[i].sock_hlen = sock_hlen;
 		mutex_unlock(&n->vqs[i].vq.mutex);
 	}
-	mutex_unlock(&n->dev.mutex);
 	return 0;
 
 out_unlock:
-	mutex_unlock(&n->dev.mutex);
 	return -EFAULT;
 }
 
@@ -1668,7 +1660,6 @@ 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;
@@ -1681,7 +1672,6 @@ static long vhost_net_set_owner(struct vhost_net *n)
 		vhost_net_clear_ubuf_info(n);
 	vhost_net_flush(n);
 out:
-	mutex_unlock(&n->dev.mutex);
 	return r;
 }
 
@@ -1721,20 +1711,18 @@ static long vhost_net_ioctl(struct vhost_dev *dev, unsigned int ioctl,
 			return -EFAULT;
 		if (features & ~VHOST_NET_BACKEND_FEATURES)
 			return -EOPNOTSUPP;
-		vhost_set_backend_features(&n->dev, features);
+		__vhost_set_backend_features(&n->dev, features);
 		return 0;
 	case VHOST_RESET_OWNER:
 		return vhost_net_reset_owner(n);
 	case VHOST_SET_OWNER:
 		return vhost_net_set_owner(n);
 	default:
-		mutex_lock(&n->dev.mutex);
 		r = vhost_dev_ioctl(&n->dev, ioctl, argp);
 		if (r == -ENOIOCTLCMD)
 			r = vhost_vring_ioctl(&n->dev, ioctl, argp);
 		else
 			vhost_net_flush(n);
-		mutex_unlock(&n->dev.mutex);
 		return r;
 	}
 }
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 9354061ce75e..9d6496b7ad85 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2821,18 +2821,24 @@ struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
 }
 EXPORT_SYMBOL_GPL(vhost_dequeue_msg);
 
-void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
+void __vhost_set_backend_features(struct vhost_dev *dev, u64 features)
 {
 	struct vhost_virtqueue *vq;
 	int i;
 
-	mutex_lock(&dev->mutex);
 	for (i = 0; i < dev->nvqs; ++i) {
 		vq = dev->vqs[i];
 		mutex_lock(&vq->mutex);
 		vq->acked_backend_features = features;
 		mutex_unlock(&vq->mutex);
 	}
+}
+EXPORT_SYMBOL_GPL(__vhost_set_backend_features);
+
+void vhost_set_backend_features(struct vhost_dev *dev, u64 features)
+{
+	mutex_lock(&dev->mutex);
+	__vhost_set_backend_features(dev, features);
 	mutex_unlock(&dev->mutex);
 }
 EXPORT_SYMBOL_GPL(vhost_set_backend_features);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 562387b92730..408ff243ed31 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -302,6 +302,7 @@ void vhost_enqueue_msg(struct vhost_dev *dev,
 struct vhost_msg_node *vhost_dequeue_msg(struct vhost_dev *dev,
 					 struct list_head *head);
 void vhost_set_backend_features(struct vhost_dev *dev, u64 features);
+void __vhost_set_backend_features(struct vhost_dev *dev, u64 features);
 
 __poll_t vhost_chr_poll(struct file *file, struct vhost_dev *dev,
 			    poll_table *wait);
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 93f74a0010d5..062767636226 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -583,8 +583,6 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
 	size_t i;
 	int ret;
 
-	mutex_lock(&vsock->dev.mutex);
-
 	ret = vhost_dev_check_owner(&vsock->dev);
 	if (ret)
 		goto err;
@@ -614,7 +612,6 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
 	 */
 	vhost_work_queue(&vsock->dev, &vsock->send_pkt_work);
 
-	mutex_unlock(&vsock->dev.mutex);
 	return 0;
 
 err_vq:
@@ -629,7 +626,6 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
 		mutex_unlock(&vq->mutex);
 	}
 err:
-	mutex_unlock(&vsock->dev.mutex);
 	return ret;
 }
 
@@ -638,8 +634,6 @@ static int vhost_vsock_stop(struct vhost_vsock *vsock)
 	size_t i;
 	int ret;
 
-	mutex_lock(&vsock->dev.mutex);
-
 	ret = vhost_dev_check_owner(&vsock->dev);
 	if (ret)
 		goto err;
@@ -653,7 +647,6 @@ static int vhost_vsock_stop(struct vhost_vsock *vsock)
 	}
 
 err:
-	mutex_unlock(&vsock->dev.mutex);
 	return ret;
 }
 
@@ -821,7 +814,6 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
 	if (features & ~VHOST_VSOCK_FEATURES)
 		return -EOPNOTSUPP;
 
-	mutex_lock(&vsock->dev.mutex);
 	if ((features & (1 << VHOST_F_LOG_ALL)) &&
 	    !vhost_log_access_ok(&vsock->dev)) {
 		goto err;
@@ -841,11 +833,9 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
 		vq->acked_features = features;
 		mutex_unlock(&vq->mutex);
 	}
-	mutex_unlock(&vsock->dev.mutex);
 	return 0;
 
 err:
-	mutex_unlock(&vsock->dev.mutex);
 	return -EFAULT;
 }
 
@@ -893,13 +883,11 @@ static long vhost_vsock_dev_ioctl(struct vhost_dev *dev, unsigned int ioctl,
 		vhost_set_backend_features(&vsock->dev, features);
 		return 0;
 	default:
-		mutex_lock(&vsock->dev.mutex);
 		r = vhost_dev_ioctl(&vsock->dev, ioctl, argp);
 		if (r == -ENOIOCTLCMD)
 			r = vhost_vring_ioctl(&vsock->dev, ioctl, argp);
 		else
 			vhost_vsock_flush(vsock);
-		mutex_unlock(&vsock->dev.mutex);
 		return r;
 	}
 }
-- 
2.28.0