staging: usbip: vhci: give back URBs from in-flight unlink requests

If we never received a RET_UNLINK because the TCP
connection broke the pending URBs still need to be
unlinked and given back.

Previously processes would be stuck trying to kill
the URB even after the device was detached.

Signed-off-by: Max Vozeler <[e-mail]>
Tested-by: Mark Wehby <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/usbip/vhci.h

···
 void vhci_rx_loop(struct usbip_task *ut);
 void vhci_tx_loop(struct usbip_task *ut);
 
+struct urb *pickup_urb_and_free_priv(struct vhci_device *vdev,
+					    __u32 seqnum);
+
 #define hardware		(&the_controller->pdev.dev)
 
 static inline struct vhci_device *port_to_vdev(__u32 port)

drivers/staging/usbip/vhci_hcd.c

···
 	return 0;
 }
 
-
 static void vhci_device_unlink_cleanup(struct vhci_device *vdev)
 {
 	struct vhci_unlink *unlink, *tmp;
···
 	spin_lock(&vdev->priv_lock);
 
 	list_for_each_entry_safe(unlink, tmp, &vdev->unlink_tx, list) {
+		usbip_uinfo("unlink cleanup tx %lu\n", unlink->unlink_seqnum);
 		list_del(&unlink->list);
 		kfree(unlink);
 	}
 
 	list_for_each_entry_safe(unlink, tmp, &vdev->unlink_rx, list) {
+		struct urb *urb;
+
+		/* give back URB of unanswered unlink request */
+		usbip_uinfo("unlink cleanup rx %lu\n", unlink->unlink_seqnum);
+
+		urb = pickup_urb_and_free_priv(vdev, unlink->unlink_seqnum);
+		if (!urb) {
+			usbip_uinfo("the urb (seqnum %lu) was already given back\n",
+							unlink->unlink_seqnum);
+			list_del(&unlink->list);
+			kfree(unlink);
+			continue;
+		}
+
+		urb->status = -ENODEV;
+
+		spin_lock(&the_controller->lock);
+		usb_hcd_unlink_urb_from_ep(vhci_to_hcd(the_controller), urb);
+		spin_unlock(&the_controller->lock);
+
+		usb_hcd_giveback_urb(vhci_to_hcd(the_controller), urb, urb->status);
+
 		list_del(&unlink->list);
 		kfree(unlink);
 	}

drivers/staging/usbip/vhci_rx.c

···
 #include "vhci.h"
 
 
-/* get URB from transmitted urb queue */
-static struct urb *pickup_urb_and_free_priv(struct vhci_device *vdev,
+/* get URB from transmitted urb queue. caller must hold vdev->priv_lock */
+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) {
···
 		}
 	}
 
-	spin_unlock(&vdev->priv_lock);
-
 	return urb;
 }
 
···
 	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",
···
 		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