USB: make sure usb serial drivers don't flush to logically disconnected devices

If disconnect() is called for a logical disconnect, no more IO must be
done after disconnect() returns, or the old and new drivers may conflict.
This patch avoids this by using the flag and lock introduced by the earlier
patch for the mos7720 driver.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 13 insertions, 9 deletions

diff --git a/drivers/usb/serial/visor.c b/drivers/usb/serial/visor.c
index 7ee087fed913..c2347995c786 100644
--- a/drivers/usb/serial/visor.c
+++ b/drivers/usb/serial/visor.c
@@ -349,16 +349,20 @@ static void visor_close (struct usb_serial_port *port, struct file * filp)
         usb_kill_urb(port->read_urb);
         usb_kill_urb(port->interrupt_in_urb);
 
-        /* Try to send shutdown message, if the device is gone, this will just fail. */
-        transfer_buffer =  kmalloc (0x12, GFP_KERNEL);
-        if (transfer_buffer) {
-                usb_control_msg (port->serial->dev,
-                                 usb_rcvctrlpipe(port->serial->dev, 0),
-                                 VISOR_CLOSE_NOTIFICATION, 0xc2,
-                                 0x0000, 0x0000, 
-                                 transfer_buffer, 0x12, 300);
-                kfree (transfer_buffer);
+        mutex_lock(&port->serial->disc_mutex);
+        if (!port->serial->disconnected) {
+                /* Try to send shutdown message, unless the device is gone */
+                transfer_buffer =  kmalloc (0x12, GFP_KERNEL);
+                if (transfer_buffer) {
+                        usb_control_msg (port->serial->dev,
+                                         usb_rcvctrlpipe(port->serial->dev, 0),
+                                         VISOR_CLOSE_NOTIFICATION, 0xc2,
+                                         0x0000, 0x0000,
+                                         transfer_buffer, 0x12, 300);
+                        kfree (transfer_buffer);
+                }
         }
+        mutex_lock(&port->serial->disc_mutex);
 
         if (stats)
                 dev_info(&port->dev, "Bytes In = %d  Bytes Out = %d\n",