USB: stop io performed by mos7720 upon close()

This fixes a problem where the mos7720 driver will make io to a device from
which it has been logically disconnected. It does so by introducing a flag by
which the generic usb serial code can signal the subdrivers their
disconnection and appropriate locking.

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

1 files changed, 18 insertions, 15 deletions

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 725991fadc26..40f3a0188807 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -564,22 +564,25 @@ static void mos7720_close(struct usb_serial_port *port, struct file *filp)
         }
 
         /* While closing port, shutdown all bulk read, write  *
-         * and interrupt read if they exists                  */
-        if (serial->dev) {
-                dbg("Shutdown bulk write");
-                usb_kill_urb(port->write_urb);
-                dbg("Shutdown bulk read");
-                usb_kill_urb(port->read_urb);
+         * and interrupt read if they exists, otherwise nop   */
+        dbg("Shutdown bulk write");
+        usb_kill_urb(port->write_urb);
+        dbg("Shutdown bulk read");
+        usb_kill_urb(port->read_urb);
+
+        mutex_lock(&serial->disc_mutex);
+        /* these commands must not be issued if the device has
+         * been disconnected */
+        if (!serial->disconnected) {
+                data = 0x00;
+                send_mos_cmd(serial, MOS_WRITE, port->number - port->serial->minor,
+                             0x04, &data);
+
+                data = 0x00;
+                send_mos_cmd(serial, MOS_WRITE, port->number - port->serial->minor,
+                             0x01, &data);
         }
-
-        data = 0x00;
-        send_mos_cmd(serial, MOS_WRITE, port->number - port->serial->minor,
-                     0x04, &data);
-
-        data = 0x00;
-        send_mos_cmd(serial, MOS_WRITE, port->number - port->serial->minor,
-                     0x01, &data);
-
+        mutex_unlock(&serial->disc_mutex);
         mos7720_port->open = 0;
 
         dbg("Leaving %s", __FUNCTION__);