sgi-xp: Use designated initializers

index c862cd4583cc..39c9e9cf4b2a 100644
@@ -309,6 +309,9 @@ static inline enum xp_retval
 xpc_send(short partid, int ch_number, u32 flags, void *payload,
 	 u16 payload_size)
 {
+	if (!xpc_interface.send)
+		return xpNotLoaded;
+
 	return xpc_interface.send(partid, ch_number, flags, payload,
 				  payload_size);
 }

@@ -317,6 +320,9 @@ static inline enum xp_retval
 xpc_send_notify(short partid, int ch_number, u32 flags, void *payload,
 		u16 payload_size, xpc_notify_func func, void *key)
 {
+	if (!xpc_interface.send_notify)
+		return xpNotLoaded;
+
 	return xpc_interface.send_notify(partid, ch_number, flags, payload,
 					 payload_size, func, key);
 }

@@ -324,12 +330,18 @@ xpc_send_notify(short partid, int ch_number, u32 flags, void *payload,
 static inline void
 xpc_received(short partid, int ch_number, void *payload)
 {
+	if (!xpc_interface.received)
+		return xpNotLoaded;
+
 	return xpc_interface.received(partid, ch_number, payload);
 }
 
 static inline enum xp_retval
 xpc_partid_to_nasids(short partid, void *nasids)
 {
+	if (!xpc_interface.partid_to_nasids)
+		return xpNotLoaded;
+
 	return xpc_interface.partid_to_nasids(partid, nasids);
 }
 

index 01be66d02ca8..6d7f557fd1c1 100644
@@ -69,23 +69,9 @@ struct xpc_registration xpc_registrations[XPC_MAX_NCHANNELS];
 EXPORT_SYMBOL_GPL(xpc_registrations);
 
 /*
- * Initialize the XPC interface to indicate that XPC isn't loaded.
+ * Initialize the XPC interface to NULL to indicate that XPC isn't loaded.
  */
-static enum xp_retval
-xpc_notloaded(void)
-{
-	return xpNotLoaded;
-}
-
-struct xpc_interface xpc_interface = {
-	(void (*)(int))xpc_notloaded,
-	(void (*)(int))xpc_notloaded,
-	(enum xp_retval(*)(short, int, u32, void *, u16))xpc_notloaded,
-	(enum xp_retval(*)(short, int, u32, void *, u16, xpc_notify_func,
-			   void *))xpc_notloaded,
-	(void (*)(short, int, void *))xpc_notloaded,
-	(enum xp_retval(*)(short, void *))xpc_notloaded
-};
+struct xpc_interface xpc_interface = { };
 EXPORT_SYMBOL_GPL(xpc_interface);
 
 /*

@@ -115,17 +101,7 @@ EXPORT_SYMBOL_GPL(xpc_set_interface);
 void
 xpc_clear_interface(void)
 {
-	xpc_interface.connect = (void (*)(int))xpc_notloaded;
-	xpc_interface.disconnect = (void (*)(int))xpc_notloaded;
-	xpc_interface.send = (enum xp_retval(*)(short, int, u32, void *, u16))
-	    xpc_notloaded;
-	xpc_interface.send_notify = (enum xp_retval(*)(short, int, u32, void *,
-						       u16, xpc_notify_func,
-						       void *))xpc_notloaded;
-	xpc_interface.received = (void (*)(short, int, void *))
-	    xpc_notloaded;
-	xpc_interface.partid_to_nasids = (enum xp_retval(*)(short, void *))
-	    xpc_notloaded;
+	memset(&xpc_interface, 0, sizeof(xpc_interface));
 }
 EXPORT_SYMBOL_GPL(xpc_clear_interface);
 

@@ -188,7 +164,8 @@ xpc_connect(int ch_number, xpc_channel_func func, void *key, u16 payload_size,
 
 	mutex_unlock(&registration->mutex);
 
-	xpc_interface.connect(ch_number);
+	if (xpc_interface.connect)
+		xpc_interface.connect(ch_number);
 
 	return xpSuccess;
 }

@@ -237,7 +214,8 @@ xpc_disconnect(int ch_number)
 	registration->assigned_limit = 0;
 	registration->idle_limit = 0;
 
-	xpc_interface.disconnect(ch_number);
+	if (xpc_interface.disconnect)
+		xpc_interface.disconnect(ch_number);
 
 	mutex_unlock(&registration->mutex);