USB: fix usb serial pm counter decrement for disconnected interfaces

usb serial decrements the pm counter even if an interface has been
disconnected. If it was a logical disconnect the interface may belong
already to another driver. This patch introduces a check for disconnected
interfaces.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Cc: Stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 3bcf3346658772e1a8efce24fd50072f5cbcf210..353798631903de1a12b429f0412d59c9d043de8b 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -283,7 +283,10 @@ static void serial_close(struct tty_struct *tty, struct file * filp)
        }
 
        if (port->open_count == 0) {
-               usb_autopm_put_interface(port->serial->interface);
+               mutex_lock(&port->serial->disc_mutex);
+               if (!port->serial->disconnected)
+                       usb_autopm_put_interface(port->serial->interface);
+               mutex_unlock(&port->serial->disc_mutex);
                module_put(port->serial->type->driver.owner);
        }