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, 4 insertions, 1 deletions

diff --git a/drivers/usb/serial/sierra.c b/drivers/usb/serial/sierra.c
index 953bdf8827d2..4c925e3e8a63 100644
--- a/drivers/usb/serial/sierra.c
+++ b/drivers/usb/serial/sierra.c
@@ -597,7 +597,10 @@ static void sierra_close(struct usb_serial_port *port, struct file *filp)
         portdata->dtr_state = 0;
 
         if (serial->dev) {
-                sierra_send_setup(port);
+                mutex_lock(&serial->disc_mutex);
+                if (!serial->disconnected)
+                        sierra_send_setup(port);
+                mutex_unlock(&serial->disc_mutex);
 
                 /* Stop reading/writing urbs */
                 for (i = 0; i < N_IN_URB; i++)