[patch]fix race between unthrottle and completion handler in visor

[Oliver Neukum <oliver@xxxxxxxxxx>]

Hi,

the same bug as opticon.

        Regards
                Oliver

Signed-off-by: Oliver Neukum <oliver@xxxxxxxxxx>

--

commit 90bf2fbef7f14ebd582607b3a740fdce2e64183d
Author: Oliver Neukum <oliver@xxxxxxxxxx>
Date:   Wed Oct 7 10:58:09 2009 +0200

    usb:usbserial:visor: fix race between unthrottle and completion handler
    
    visor_unthrottle() mustn't resubmit the URB unconditionally
    as the URB may still be running.

diff --git a/drivers/usb/serial/visor.c b/drivers/usb/serial/visor.c
index b9341f0..ad1f923 100644
--- a/drivers/usb/serial/visor.c
+++ b/drivers/usb/serial/visor.c
@@ -595,20 +595,23 @@ static void visor_unthrottle(struct tty_struct *tty)
 {
 	struct usb_serial_port *port = tty->driver_data;
 	struct visor_private *priv = usb_get_serial_port_data(port);
-	int result;
+	int result, was_throttled;
 
 	dbg("%s - port %d", __func__, port->number);
 	spin_lock_irq(&priv->lock);
 	priv->throttled = 0;
+	was_throttled = priv->actually_throttled;
 	priv->actually_throttled = 0;
 	spin_unlock_irq(&priv->lock);
 
-	port->read_urb->dev = port->serial->dev;
-	result = usb_submit_urb(port->read_urb, GFP_KERNEL);
-	if (result)
-		dev_err(&port->dev,
-			"%s - failed submitting read urb, error %d\n",
+	if (was_throttled) {
+		port->read_urb->dev = port->serial->dev;
+		result = usb_submit_urb(port->read_urb, GFP_KERNEL);
+		if (result)
+			dev_err(&port->dev,
+				"%s - failed submitting read urb, error %d\n",
 							__func__, result);
+	}
 }
 
 static int palm_os_3_probe(struct usb_serial *serial,

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