--- 8ed52063edb88cf4ba0a2b860989b371a25233df
+++ 7636d86c23881589346167506f098e055aa4cafa
@@ -21,14 +21,16 @@
 #include "vhci.h"
 
 
-/* get URB from transmitted urb queue. caller must hold vdev->priv_lock */
-struct urb *pickup_urb_and_free_priv(struct vhci_device *vdev,
+/* get URB from transmitted urb queue */
+static struct urb *pickup_urb_and_free_priv(struct vhci_device *vdev,
 					    __u32 seqnum)
 {
 	struct vhci_priv *priv, *tmp;
 	struct urb *urb = NULL;
 	int status;
 
+	spin_lock(&vdev->priv_lock);
+
 	list_for_each_entry_safe(priv, tmp, &vdev->priv_rx, list) {
 		if (priv->seqnum == seqnum) {
 			urb = priv->urb;
@@ -59,6 +61,8 @@ struct urb *pickup_urb_and_free_priv(str
 		}
 	}
 
+	spin_unlock(&vdev->priv_lock);
+
 	return urb;
 }
 
@@ -68,11 +72,9 @@ static void vhci_recv_ret_submit(struct
 	struct usbip_device *ud = &vdev->ud;
 	struct urb *urb;
 
-	spin_lock(&vdev->priv_lock);
 
 	urb = pickup_urb_and_free_priv(vdev, pdu->base.seqnum);
 
-	spin_unlock(&vdev->priv_lock);
 
 	if (!urb) {
 		usbip_uerr("cannot find a urb of seqnum %u\n",
@@ -97,9 +99,6 @@ static void vhci_recv_ret_submit(struct
 	if (usbip_recv_iso(ud, urb) < 0)
 		return;
 
-	/* restore the padding in iso packets */
-	if (usbip_pad_iso(ud, urb) < 0)
-		return;
 
 	if (usbip_dbg_flag_vhci_rx)
 		usbip_dump_urb(urb);
@@ -160,12 +159,7 @@ static void vhci_recv_ret_unlink(struct
 		return;
 	}
 
-	spin_lock(&vdev->priv_lock);
-
 	urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
-
-	spin_unlock(&vdev->priv_lock);
-
 	if (!urb) {
 		/*
 		 * I get the result of a unlink request. But, it seems that I