vhost-net: batch use/unuse mm

Move use/unuse mm to vhost.c which makes it possible to batch these
operations.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

drivers/vhost/net.c

@@ -10,7 +10,6 @@
 #include <linux/eventfd.h>
 #include <linux/vhost.h>
 #include <linux/virtio_net.h>
-#include <linux/mmu_context.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -142,7 +141,6 @@ static void handle_tx(struct vhost_net *net)
 		return;
 	}
 
-	use_mm(net->dev.mm);
 	mutex_lock(&vq->mutex);
 	vhost_disable_notify(vq);
 
@@ -207,7 +205,6 @@ static void handle_tx(struct vhost_net *net)
 	}
 
 	mutex_unlock(&vq->mutex);
-	unuse_mm(net->dev.mm);
 }
 
 static int peek_head_len(struct sock *sk)
@@ -312,7 +309,6 @@ static void handle_rx_big(struct vhost_net *net)
 	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
 		return;
 
-	use_mm(net->dev.mm);
 	mutex_lock(&vq->mutex);
 	vhost_disable_notify(vq);
 	hdr_size = vq->vhost_hlen;
@@ -391,7 +387,6 @@ static void handle_rx_big(struct vhost_net *net)
 	}
 
 	mutex_unlock(&vq->mutex);
-	unuse_mm(net->dev.mm);
 }
 
 /* Expects to be always run from workqueue - which acts as
@@ -423,7 +418,6 @@ static void handle_rx_mergeable(struct vhost_net *net)
 	if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
 		return;
 
-	use_mm(net->dev.mm);
 	mutex_lock(&vq->mutex);
 	vhost_disable_notify(vq);
 	vhost_hlen = vq->vhost_hlen;
@@ -500,7 +494,6 @@ static void handle_rx_mergeable(struct vhost_net *net)
 	}
 
 	mutex_unlock(&vq->mutex);
-	unuse_mm(net->dev.mm);
 }
 
 static void handle_rx(struct vhost_net *net)

drivers/vhost/vhost.c

@@ -15,6 +15,7 @@
 #include <linux/vhost.h>
 #include <linux/virtio_net.h>
 #include <linux/mm.h>
+#include <linux/mmu_context.h>
 #include <linux/miscdevice.h>
 #include <linux/mutex.h>
 #include <linux/rcupdate.h>
@@ -177,6 +178,8 @@ static int vhost_worker(void *data)
 	struct vhost_work *work = NULL;
 	unsigned uninitialized_var(seq);
 
+	use_mm(dev->mm);
+
 	for (;;) {
 		/* mb paired w/ kthread_stop */
 		set_current_state(TASK_INTERRUPTIBLE);
@@ -191,7 +194,7 @@ static int vhost_worker(void *data)
 		if (kthread_should_stop()) {
 			spin_unlock_irq(&dev->work_lock);
 			__set_current_state(TASK_RUNNING);
-			return 0;
+			break;
 		}
 		if (!list_empty(&dev->work_list)) {
 			work = list_first_entry(&dev->work_list,
@@ -209,6 +212,8 @@ static int vhost_worker(void *data)
 			schedule();
 
 	}
+	unuse_mm(dev->mm);
+	return 0;
 }
 
 /* Helper to allocate iovec buffers for all vqs. */