usb-serial: ftdi_sio: fix oops during autosuspend

This patch (as1550) fixes a bug in the usb-serial core that affects
the ftdi_sio driver and most likely others as well.  The core
implements suspend and resume routines, but it doesn't store pointers
to those routines in the usb_driver structures that it registers,
even though it does set those drivers' supports_autosuspend flag.  The
end result is that when one of these devices is autosuspended, we try
to call through a NULL pointer.

The patch fixes the problem by setting the suspend and resume method
pointers to the appropriate routines in the USB serial core, along
with the supports_autosuspend field, in each driver as it is
registered.

This should be back-ported to all the stable kernels that have the new
usb_serial_register_drivers() interface.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: Frank Schäfer <schaefer.frank@gmx.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 906f06e97fde..f7b263e237ef 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -1336,7 +1336,6 @@ static int usb_serial_register(struct usb_serial_driver *driver)
                                 driver->description);
                 return -EINVAL;
         }
-        driver->usb_driver->supports_autosuspend = 1;
 
         /* Add this device to our list of devices */
         mutex_lock(&table_lock);
@@ -1371,7 +1370,7 @@ static void usb_serial_deregister(struct usb_serial_driver *device)
  * @serial_drivers: NULL-terminated array of pointers to drivers to be registered
  *
  * Registers @udriver and all the drivers in the @serial_drivers array.
- * Automatically fills in the .no_dynamic_id field in @udriver and
+ * Automatically fills in the .no_dynamic_id and PM fields in @udriver and
  * the .usb_driver field in each serial driver.
  */
 int usb_serial_register_drivers(struct usb_driver *udriver,
@@ -1390,11 +1389,17 @@ int usb_serial_register_drivers(struct usb_driver *udriver,
          * the serial drivers are registered, because the probe would
          * simply fail for lack of a matching serial driver.
          * Therefore save off udriver's id_table until we are all set.
+         *
+         * Suspend/resume support is implemented in the usb-serial core,
+         * so fill in the PM-related fields in udriver.
          */
         saved_id_table = udriver->id_table;
         udriver->id_table = NULL;
 
         udriver->no_dynamic_id = 1;
+        udriver->supports_autosuspend = 1;
+        udriver->suspend = usb_serial_suspend;
+        udriver->resume = usb_serial_resume;
         rc = usb_register(udriver);
         if (rc)
                 return rc;