usb: roles: Take care of driver module reference counting

This fixes potential "BUG: unable to handle kernel paging
request at ..." from happening.

Fixes: fde0aa6c175a ("usb: common: Small class for USB role switches")
Cc: <stable@vger.kernel.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/common/roles.c b/drivers/usb/common/roles.c
index 15cc76e22123e7044c77dc5b436ec13916dc83f1..99116af07f1d9ca1e7c275a70122f370ec0d32a3 100644 (file)
--- a/drivers/usb/common/roles.c
+++ b/drivers/usb/common/roles.c
@@ -109,8 +109,15 @@ static void *usb_role_switch_match(struct device_connection *con, int ep,
  */
 struct usb_role_switch *usb_role_switch_get(struct device *dev)
 {
-       return device_connection_find_match(dev, "usb-role-switch", NULL,
-                                           usb_role_switch_match);
+       struct usb_role_switch *sw;
+
+       sw = device_connection_find_match(dev, "usb-role-switch", NULL,
+                                         usb_role_switch_match);
+
+       if (!IS_ERR_OR_NULL(sw))
+               WARN_ON(!try_module_get(sw->dev.parent->driver->owner));
+
+       return sw;
 }
 EXPORT_SYMBOL_GPL(usb_role_switch_get);
 
@@ -122,8 +129,10 @@ EXPORT_SYMBOL_GPL(usb_role_switch_get);
  */
 void usb_role_switch_put(struct usb_role_switch *sw)
 {
-       if (!IS_ERR_OR_NULL(sw))
+       if (!IS_ERR_OR_NULL(sw)) {
                put_device(&sw->dev);
+               module_put(sw->dev.parent->driver->owner);
+       }
 }
 EXPORT_SYMBOL_GPL(usb_role_switch_put);