xenbus: simplify xenbus_dev_request_and_reply()

No need to retain a local copy of the full request message, only the
type is really needed.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

drivers/xen/xenbus/xenbus_xs.c

@@ -232,10 +232,10 @@ static void transaction_resume(void)
 void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg)
 {
 	void *ret;
-	struct xsd_sockmsg req_msg = *msg;
+	enum xsd_sockmsg_type type = msg->type;
 	int err;
 
-	if (req_msg.type == XS_TRANSACTION_START)
+	if (type == XS_TRANSACTION_START)
 		transaction_start();
 
 	mutex_lock(&xs_state.request_mutex);
@@ -250,8 +250,7 @@ void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg)
 	mutex_unlock(&xs_state.request_mutex);
 
 	if ((msg->type == XS_TRANSACTION_END) ||
-	    ((req_msg.type == XS_TRANSACTION_START) &&
-	     (msg->type == XS_ERROR)))
+	    ((type == XS_TRANSACTION_START) && (msg->type == XS_ERROR)))
 		transaction_end();
 
 	return ret;