USB: usb_wwan: fix urb leak at shutdown

commit 79eed03e upstream.

The delayed-write queue was never emptied at shutdown (close), something
which could lead to leaked urbs if the port is closed before being
runtime resumed due to a write.

When this happens the output buffer would not drain on close
(closing_wait timeout), and after consecutive opens, writes could be
corrupted with previously buffered data, transfered with reduced
throughput or completely blocked.

Note that unbusy_queued_urb() was simply moved out of CONFIG_PM.

Fixes: 383cedc3 ("USB: serial: full autosuspend support for the
option driver")
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/serial/usb_wwan.c

@@ -434,12 +434,26 @@ int usb_wwan_open(struct tty_struct *tty, struct usb_serial_port *port)
 }
 EXPORT_SYMBOL(usb_wwan_open);
 
+static void unbusy_queued_urb(struct urb *urb,
+					struct usb_wwan_port_private *portdata)
+{
+	int i;
+
+	for (i = 0; i < N_OUT_URB; i++) {
+		if (urb == portdata->out_urbs[i]) {
+			clear_bit(i, &portdata->out_busy);
+			break;
+		}
+	}
+}
+
 void usb_wwan_close(struct usb_serial_port *port)
 {
 	int i;
 	struct usb_serial *serial = port->serial;
 	struct usb_wwan_port_private *portdata;
 	struct usb_wwan_intf_private *intfdata = port->serial->private;
+	struct urb *urb;
 
 	dbg("%s", __func__);
 	portdata = usb_get_serial_port_data(port);
@@ -450,6 +464,14 @@ void usb_wwan_close(struct usb_serial_port *port)
 		portdata->opened = 0;
 		spin_unlock_irq(&intfdata->susp_lock);
 
+		for (;;) {
+			urb = usb_get_from_anchor(&portdata->delayed);
+			if (!urb)
+				break;
+			unbusy_queued_urb(urb, portdata);
+			usb_autopm_put_interface_async(serial->interface);
+		}
+
 		for (i = 0; i < N_IN_URB; i++)
 			usb_kill_urb(portdata->in_urbs[i]);
 		for (i = 0; i < N_OUT_URB; i++)
@@ -666,18 +688,6 @@ int usb_wwan_suspend(struct usb_serial *serial, pm_message_t message)
 }
 EXPORT_SYMBOL(usb_wwan_suspend);
 
-static void unbusy_queued_urb(struct urb *urb, struct usb_wwan_port_private *portdata)
-{
-	int i;
-
-	for (i = 0; i < N_OUT_URB; i++) {
-		if (urb == portdata->out_urbs[i]) {
-			clear_bit(i, &portdata->out_busy);
-			break;
-		}
-	}
-}
-
 static void play_delayed(struct usb_serial_port *port)
 {
 	struct usb_wwan_intf_private *data;